My 4-Inch Kestrel - Can I Keep It Under 250 Grams?

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My open-source Kestrel frame is easily configurable. For my first build, I filled the frame with components that I already had on hand—the guts from a Leader 3 bind-n-fly quad. I knew that I wanted to try to fit a 4” HD quad in under the 250-gram limit, but I wanted to work out as many design bugs as I could first.

The design work on the Kestrel is pretty much complete. I found a few bugs when assembling my 4” build that didn’t show up on the 3”, but they were all easy to correct, and the changes didn’t introduce any incompatibilities with my official 1.0 release. I’m so glad I don’t have to increment to version 2.0 already!

I don’t have any sort of legal requirement to stay under 250 grams, so I’m just using that figure as a guideline. I can get away with using components that aren’t quite suited to the lightest build possible. The FC, ESC, and VTX modules are overweight, but they really aren’t all that heavy. Using lighter, less-capable electronics might have saved me 10 to 15 grams.

That’s not a lot of weight, but my build comes in at 270 grams with a 650 mAh 4S battery. My build does manage to come in at 244 grams with a 450 mAh 4S battery, but that battery is on the small side.

I’m right on the edge here. If I could save 10 grams on my components, and then save another 10 grams by using a 550 or 600 mAh battery, that would be awesome!

My goals for this build

I’m writing this section of the blog before having a chance to actually fly my 4” Kestrel build. It is fully assembled and configured, and it survived a test hover in the front yard last night. It has been raining all day, so I won’t be testing it for a few days.

I want to be honest. I want to tell you what I’m hoping to get out of this build before I can actually verify my hopes and hypotheses!

I used to fly 6” and 5.5” props on my freestyle miniquads. I didn’t fly 6” for long, but I flew 5.5” props for the better part of a year. On the same quad with the same motors, 5” props are more responsive and have a higher top speed compared to 6” props. 6” props have more bottom end that you’ll really notice when pulling out of a dive, and they are significantly more efficient.

5.5” props land somewhere in the middle, but I used to get about 20% more flight time compared to 5” props. Will this relationship between 3” and 4” be similar to the relationship between 5” and 6”? That’s my hope!

I’m a little concerned, though. I once tried 6” props on my BFight 210 with it’s 2204 motors. I didn’t lose any flight time, but I didn’t gain any, either. The 6” props were just too heavy for those motors. Will the 1606 motors be beefy enough for 4” props?

I’m expecting significantly longer flights out of the 4” props, assuming the motors I chose don’t wind up being ridiculously underpowered. I owned a 4” FPV miniquad a long time ago. It was big, heavy, and used 2204 motors and 1,300 mAh 4S batteries.

I expect the 4” setup to be smoother than a 3”, and I’m hoping it doesn’t feel too sluggish when doing snappy freestyle. I feel like my 220-gram 3” Kestrel might be a bit too snappy, so I’m thinking I might enjoy the 4” build!

What if it is terrible at freestyle?! I decided to use a big, heavy 1,000 mW VTX in my build. Assuming that I’m correct about this being more efficient, I would enjoy the idea of having a sub-250 gram medium-to-long-range HD quad!

I don’t trust static thrust tests—especially from manufacturers! A quick look at the numbers tells me that the 4” props on the 1606 motors should be able to cruise along at 30 to 40 MPH while consuming about 40% less power. They’re also capable of producing nearly double the amount of thrust with 4” props, but at the cost of about 30% higher amps. How is that going to work out in the real world?

If things work out in my favor, I will be able to cruise longer and meet or exceed my 3” Kestrel’s flight times when doing aggressive freestyle.

The parts list

My old 4” Holybro Shuriken 180 Pro was a scaled-down 5” racing quad. My new build is attacking this problem from the opposite direction. I’m scaling up a 3” micro, so instead of using 2204 2750 kv motors, I’m using EMAX 1606 3300 kv motors. This is why I’m referring to my build as a light 4” quad.

  • 4” Kestrel frame
  • EMAX 1606 3300 kv motors (4)
  • Aikon 20x20 AK32PIN 35a blheli32 4-in-1 ESC
  • Aikon 20x20 F4 flight controller
  • RaceDayQuads Mach 3 1000 mW VTX (mmcx)
  • Luminier AXII antenna (mmcx)
  • Caddx Turtle V2
  • TBS Crossfire Nano

The Aikon stack is total overkill for this build. That little 20x20 stack can easily power a 5” 6S racing quad. It would have absolutely no trouble driving my 680-gram 5” freestyle quads.

I’m certain that there is a cheaper, smaller, lighter FC and ESC combo that could drive these motors and props. This is going to be my test platform, though. I have a plethora of interesting motors and props lying around. I have some efficient 2205 motors that I’d like to try with 5” props. I have all sorts of 2306 and 2207 motors, too. Maybe I’ll try a ridiculous 6” Kestrel. It is easy to cut arms and stick them on this fuselage!

My 4-inch Kestrel

The VTX and antenna are on the heavy side, too. The VTX is only 6.5 grams, and the AXII only adds another 2 or 3 grams. The little 200 mW VTX and tiny whip antenna from my Leader 3 weighs less than 4 grams.

These heavy components are buying me versatility for testing and some extra VTX juice for long range. I guess my light 4” build is a bit on the tubby side!

Minor problems with my Kestrel design!

I was worried that the Aikon AK32PIN would be too long to comfortably fit on my Kestrel’s bottom plate. I didn’t want to alter the spacing between the mounting points of the side plates, but I could see that there was some wiggle room to push the front and rear stacks closer to the edges.

I was only able to move each stack forward or backward by 3 mm, and that made the build a lot more comfortable. Unfortunately, this also pushed my Caddx Turtle’s 20x20 board too close to the camera!

I raised the top plate a bit to make more room for the stack. The combination of the bottom plate, side plates, and the bushings that hold everything together is rigid enough, but it will flex quite a bit in a crash. This will make it harder to damage your flight controller in a crash, and give you a bit more room to build.

The center stack uses M3 holes as of version 1.0. I have grommets to bring those holes down to size for M2 stacks while providing a bit of vibration isolation for your flight controller. The grommets work great, and the M2 screws are no problem.

I didn’t remember to leave clearance for the head of an M3 screw! There’s a cutout in each arm that leaves enough room, but the arm bracing plate won’t let an M3 screw head pass. This was an easy problem to correct, and I was able to work around the issue when assembling my 4” Kestrel with an M3 center stack.

How does the 4” Kestrel fly?

Other than a few mistakes that I’ve made, the 4” Kestrel is flying great! A lot of what I suspected is true. Even though it is only 20 or 30 grams heavier than most 3” builds, it feels bigger. It reminds me more of flying a 5.5” or 6” quad. It still gets up to top speed quickly, and it catches itself from a fall with barely any throttle.

What kind of mistakes did I make? My side plates are rather floppy, and I’m only certain about what caused one of the problems that has these things flopping around!

When I moved the front and rear stacks outward, that created an opportunity to carve some material out of the bottom plate. This was a mistake, because my bottom plate is now quite flexible!

Also, a pair of my bushings are fitting loosely, but only on the left side! These aren’t fresh bushings, but they don’t have a lot of mileage on them, either. I’ve adjusted the bushing holes and the tabs with every prototype. I think I’ve just pushed things too far. I’ve added 0.5 mm back into the tabs in the model. We’ll see if that fits better.

My side plates are floppy enough that the camera shakes around. It looks terrible!

I also made a mistake regarding the propellers. I had a few pairs of HQ 4x4.3x3 v1s props in my drawer. I shopped around a bit, and that was the gentlest prop I found, so I ordered a few more.

GetFPV is one of the few stores that stocks HQ 4x3x3 v1s props. I haven’t flown them yet, but I’m excited to try them. They should be arriving before the end of the week.

I don’t think 4” props are ridiculous for a 1606 motor, but I’ve been worried that the HQ 4x4.3x3 would be too aggressive for such a small motor. It flies well, but it isn’t as efficient as my 3” 1306 Kestrel with HQ 3x3x3 props.

The 4.3 pitch props cruise at around 35 MPH with 22% throttle. That’s at least 10% less throttle than my 3” Kestrel. I spent an entire 650 mAh pack flying around like that, and couldn’t fly any longer than 6 minutes. My 3” Kestrel usually hits 5 minutes doing pretty aggressive, heavy-throttle freestyle. I’ve never tried for endurance on the 3”, but I know I’ve accidentally flown longer than 6 minutes on it before!


So far, I like the 4” Kestrel, and it is showing some promise. If all the HQ 4x3x3 props wind up doing is bringing the efficiency in line with my 3” build, I’ll be extremely pleased. I think I’m going to enjoy the 4” build more than my 3”, even if it doesn’t offer me longer flights. It just suits my flying style a bit more!

I believe there’s a good chance I’ll see significantly longer flight times out of the gentler pitch 4” props. It would be nice to be able to put that heavy 1000 mW VTX to good use. I’ll know in just a few days, but I’m not patient enough to wait until then to publish this blog!

Do you think I’ll get an extra minute or two out of the HQ 4x3x3 props? Do you think a similar build could be squeezed in under 250 grams with a big battery if I used a lighter FC, ESC, and VTX? Or do you think I should stick to 3”? Do you have any questions? Let me know in the comments, or stop by our Discord server to have a chat!

Expensive FPV Gear Doesn’t Always Boost Your Confidence

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Confidence is important when flying FPV freestyle. If you’re nervous and shaky when you’re aiming for a gap or trying to clear a tree, you’re much more likely to miss the gap or get stuck in the tree.

When I was flying FrSky receivers in my quads, I was often nervous when flying over trees. At the time, I didn’t think I was hitting failsafes all that often, but I bet I was losing my control link once every week or so. I didn’t think it was all that problematic at the time, but every time I lost control, it was like resetting my confidence’s timer.

I’d be nervous for a few days—especially when I was upside down over a tall tree! I’d start getting my confidence back, and then I’d hit another failsafe.

Having reliable gear is important, and my gear wasn’t reliable enough. I invested a few hundred dollars into TBS Crossfire hardware, and this problem was almost completely eliminated. You can’t completely eliminate failsafes, but they are no longer a regular occurrence for me.

You can often spend some of your hard-earned money to buy yourself some extra confidence.

Flying an expensive FPV quad can be scary!

The first time I decided to fly my quad over a little creek, I was nervous. My thumbs were shaky. I wasn’t really prepared to climb down the ten-foot ledge or go swimming to retrieve my stuff. Visibility under all the trees wasn’t great, so I was worried a ghost branch would pop up at the last second.

I swapped my $200 GoPro HERO5 Session for my older $100 GoPro Session. I was still sending $650 or so down into that creek. I could lose a $40 Crossfire Nano, a $60 ESC board, a $45 Runcam Eagle, and all sorts of other bits and bobs. A slew of $50 components adds up quickly!

These days, I have an even less risky option. My 3” Kestrel build with Caddx Turtle V2 HD camera costs less than $250. I have a lot more confidence when I’m sending $250 into a precarious situation!

Start with inexpensive quads

If you’re new to the hobby, you’re going to goof up. You’re going to obliterate a quad. You’re likely to lose a quad.

We hosted three different quadcopter build classes at makerspace. We cautioned everyone. After a large 450 mm quad flew away on someone from the first class, we started really hammering those words of caution into everyone. Even so, someone lost a quad within a few days of each class! They were so far gone that we never saw them again.

I’d rather see you get this out of your system with a junker of a quad. I’d be bummed out if I helped you build something like the $600 quads I fly, and you wound up losing it the first time you went out flying by yourself. I’d much rather see you lose a $130 BFight 210. Does anyone know what the modern equivalent of the BFight 210 happens to be?!

The BFight 210 was great. At least four of my friends flew them, and they flew them a lot! They’re light, inexpensive, and surprisingly durable 5” FPV quads. They are a little under-powered, but they’re efficient. Beginners are regularly getting 10-minute flights out of their BFight 210 quads, but they’d feel much too heavy with a GoPro strapped to the top.

That’s OK, though. Losing a GoPro is a bummer. You should definitely buy accidental damage insurance, but that insurance only works if you manage to recover the camera! The first time I strapped an HD camera to the top of my quad, it flew off in a crash. The TPU mounts we use today work much better, but losing your camera or your entire quad is still a risk.

You’ll be braver with less than $150 in the air than you would be when risking $350 or $500 on a flight!

A light, budget-friendly build of my 3” Kestrel can be squeezed in at around $250. 3” quads don’t feel as solid and locked in as a 5”, but it is a great way to get started if you really must have HD recording capabilities right away.

Upgrade the gear in your hands first

You use a lot of expensive gear when you fly, but the only piece of equipment that’s really at risk is the quadcopter and its payload. The rest of your gear is sitting safely in your hands or on your head!

When I started out, I used a cheap 200 mW VTX on my quad, and a cheap set of box goggles. Even with a directional antenna, we felt like flying 1,200 feet away at a low altitude in an open field was pushing the limits of our video quality. I used to tolerate some pretty awful video in those days. What do you expect from a $12 VTX and a $50 set of goggles?

Upgrade your goggles and video receiver

Today, I use a better VTX, and I’ve upgraded to a set of Fat Shark Dominator goggles with an [ImmersionRC RapidFire module][rf]. My new setup costs ten times more than my first set of box goggles, but I couldn’t imagine going back!

I rarely use a directional antenna on my RapidFire module. I almost always fly with a pair of omni antennas. We often fly at an abandoned golf course here in town, and I regularly fly 1,500 feet away without a directional antenna. I didn’t even realize I’ve been flying that far until I checked a map! I’ve even dropped down into a creek to fly under a bridge that was 1,200 feet away.

Fat Shark Dominators with RapidFire module

Needless to say, upgrading to a RapidFire module has been a huge confidence boost. Most of the time, though, the RX5808 module that I had when I bought my Fat Shark goggles was just fine, and a huge upgrade over the cheap box goggles.

Upgrade your radio

If you went the cheap route on your radio, with something like a FlySky FS-i6 or Turnigy Evolution, you should think about upgrading your radio before upgrading your quad. Crossfire modules have dropped in price to compete with FrSky’s R9 gear, and I would almost recommend skipping FrSky’s 2.4 GHz hardware.

Taranis X9D+ and Spektrum DX6

I’m still a fan of the Taranis X9D+. It costs a bit more than the Taranis QX 7, but it comes with a rechargeable battery, a charger, and it is compatible with Crossfire without any soldering. Buying a rechargeable battery for the QX 7 eats into your savings, and having to remove the battery to charge it is a pain. The NiMH battery in the X9D+ isn’t great, but it sure is convenient!

The Underground FPV Nirvana radio looks interesting, too. I fly with my thumbs, so it would be a comfortable radio for me. The FlySky antenna can be folded out of the way, and it is compatible with Crossfire right out of the box.

Upgrade your charging setup

This won’t help you fly, but it might save you some time and effort, and that time savings will pay off over the long run.

I started out using one of the cheap “4-button” chargers. It maxed out at around 5 amps. That wasn’t a problem, until I learned how to parallel charge.

I’ve since upgraded to an ISDT Q6-Pro, and I have the charger attached to a Bat-Safe. The Q6 Pro maxes out at around 14 amps. I can charge six 1300 mAh 5S packs in just over 22 minutes.

My Field Charging Setup

The ISDT charger has a nicer interface, and it can balance charge roughly three times faster than my old charger. I believe this is why the ISDT charges so much faster than my old charger, even when both are pushing the same amperage.

Waiting an hour for six batteries to parallel charge on my original charger wasn’t a huge problem, but it was an annoyance if I needed to charge more than six batteries—six identical batteries, even!

It is nice to be able to charge a set of 5S, a set of 6S, and a set of micro-sized 4S packs in about an hour, even if it doesn’t actually help me fly any better!

Upgrade your bag

I remember being very excited when a whole bunch of research pointed me towards the $15 tactical backpacks. There were quite a few people excited about them, including Stew from UAV Futures. It was a good deal, and I really did like that bag.

My Old Tactical Backpack

I didn’t realize how much time I was wasting every time I went flying. I usually had to unstrap a couple of quads from the outside of the bag, and I had to unpack my box goggles, Taranis, and my battery bag before I could get started. I also needed room to set all that stuff down somewhere near the bag.

When I was done flying, I had to carefully fit all that stuff back into my bag. It took a few minutes to unpack, and then roughly twice as long to repack the bag.

I’ve since upgraded to an expensive FPV backpack—a ThinkTank FPV Airport Helipak. I’m not saying you should go out and buy a $200 backpack, but I’m so happy that I did!

With a big bag like this, I just set it down, open the lid, and start flying. Everything has its own spot, and nothing important has to be loaded underneath other items. I can remove or replace batteries, my Taranis, my goggles, or a quad quickly and easily. I don’t set anything down next to my bag anymore.

My ThinkTank FPV Airport Helipak

When I put down my radio or goggles, they go right back in their assigned home. When it is time to leave, I don’t have much more to do than zip up my bag and pack up my chair.

This may seem like a minor victory, but I’m saving myself ten to fifteen minutes every time I fly. Sometimes that means I can get one or two more batteries in before it gets dark. Is that worth $200? How much is it worth to you to get one more pack in, and how many times does this have to happen before the bag has paid for itself?

You don’t have to spend $200 on a backpack. I also have an AmazonBasics DSLR backpack. It is much smaller, so I can’t pack everything in there—the soldering iron and field charging battery have to stay at home!

It is great for when I hop on my electric bike to ride to the park. My fully-loaded ThinkTank bag weighs 26 pounds. The smaller backpack never weighs more than 12 pounds.

With that smaller bag, I can either bring my 3” Kestrel and 90 minutes’ worth of battery, or I can bring my 5” Flowride and 20 minutes’ worth of batteries. I can’t fit as much in there, but I operate it just like the ThinkTank bag—everything has a place, and gear goes back in that place when I’m not using it.

Either bag is more efficient in the field than the old $15 tactical backpack. People often say that the best bag for your FPV gear is the bag you already have. No matter what sort of bag you use, you should do your best to make efficient use of it.


Sometimes you can spend money to buy confidence. If you keep burning out ESCs, have a flaky gyro on your flight controller, or your quad sometimes just does a flip of death for no reason, then you are just going to have to spend some cash to fix it. If you just can’t see where you’re going, you might have to buy a better camera or VTX.

I don’t know about you, but my nerves can’t always handle flying 680 grams and $750 in new or scary situations. My thumbs get shaky if I might smash a heavy quad into somebody’s car, or I might drop my quad and GoPro into a lake or river.

My 4-inch Kestrel HD Quad

I like having a $250 HD quad to get myself warmed up in new places or situations. I hope to be a better pilot one day, and those situations won’t feel new or scary anymore. Until that day, I’m going to make sure I carry an inexpensive quad!

What do you think? Do you sometimes get shaky thumbs when flying in a new or sketchy spot? Do you carry an old quad or a cheap quad for those situations? Tell me about in a comment, or stop by and chat about it on out Discord server!

Building a NAS: Buy Lots of Drives or Just What You Need?

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So, you’ve decided that you want to build your own NAS. I bet you’re investigating hard drive prices and your options for RAID levels. At least, I hope you are!

Should you buy the biggest disks on the market? Do you have to buy all your disks up front? Should you use ZFS or a more traditional RAID setup? How much redundancy do you need?

Some of Brian's NAS builds

There are so many questions, and there is no single answer that fits everyone situation. I’m going to attempt to answer some these questions from my current point of view. My hope is that you and I are in similar situations!

My home NAS stores my important, personal data. I created all of this important data myself, and I’m spending money out of my own pocket on this hardware. I paid for the cameras that take the photos and record the video. I paid for the drones that capture the video that accounts for the bulk of my storage these days. I paid for the server and all the hard drives.

I prefer to keep as much money in my wallet as possible. In the past, it has been my job to spend other people’s money on things like this. They paid me to choose the hardware. They paid me to configure the hardware. They paid me to maintain and support the hardware. Well, not just me. In most cases, I was part of a team of people.

When spending other people’s money, I’m happy to pay for extra stuff. If there’s a 0.1% chance that using something like ECC RAM could keep me from getting out of bed at 3:00 AM, that would have been worth quite a few hundreds or thousands of extra dollars; after all, it isn’t my money!

If my home NAS fails at 3:00 AM, I won’t notice until the afternoon of the next day. I have backups. I know my data will be easily available on another machine in the house. If the house burns down, all my data is sitting on a different continent. I’ll be able to get it back.

Do I need to buy all my drives up front?

It depends.

When my friend Brian built his first DIY NAS back in 2012, I told him that he needed to give ZFS a try. ZFS has been around a long time, but it was only a part of FreeNAS or FreeBSD for a couple years at that point. ZFS has a lot of useful, advanced features: block-level checksums, extremely flexible snapshot and volume management, and RAID rebuilds don’t touch unused parts of the file system.

Even today, though, ZFS has one major disadvantage over something like Linux’s software RAID system. ZFS doesn’t allow you to add additional drives to an existing zpool. If you want to be efficient with ZFS, you need to build your array with as many disks as you can right away.

Let’s say your little home server has room for eight drives. For the sake of simple math, let’s say you decided to use 1 TB drives that cost $100 each, and you want to have one disk worth of redundancy in your array.

If you buy eight disks and configure set them up as a ZFS RAID-Z array or a traditional RAID 6 array, it will cost $800 for 7 TB of usable space.

You don’t need 7 TB today. You only need 3 TB, and you know these 1 TB drives will be half the price in a couple years. So you buy four disks. Now your smaller RAID-Z has 3 TB of usable space, but it only cost you $400.

What do you do in two or three years when you run out of space? If you’re running ZFS, you can’t just plunk in another drive.

You can replace your 1 TB drives one at a time with 2 TB drives. When you replace the final drive, you will have doubled your space. This can be an expensive operation, and you’ll may be stuck with four old, unused drives.

You can add four more drives. You’ll have to create another zpool, which means you will lose one more disk’s worth of storage to your RAID-Z redundancy. Maybe you’ve lucked out, though, and 2 TB drives now cost $100. You’ll have two redundant disks and a total of 9 TB of usable space. That’s nearly 30% more storage for the same price, and you’ve managed to gain a little more redundancy.

Will disks be twice the size for the same cost when you decide to upgrade? I can’t tell you that. So far, we’re just making up prices to help form a picture in your mind.

You can add disks to Linux’s software RAID arrays after they’re built

Let’s go back to the point where you decided to start with four drives, but instead of running ZFS, let’s use Linux’s MD layer to built a RAID 5 array.

What happens in two years when you run out of space? You don’t have to spend $400 on another set of disks. You can buy just one more 1 TB disk, or you can future-proof yourself a bit and add a 2 TB disk instead. Either way, you can pop that disk in, run a few simple commands, and in a few hours you’ll have an extra 1 TB of space available on your RAID 5 array.

Each time you begin to run low on space, you can simply buy another disk—at least until you fill up your case!

Don’t use RAID 5 or RAID-Z

RAID levels that use parity for redundancy, like RAID 5 or RAID-Z, are great when you’re on a budget and write speeds aren’t important for your workload. Any reasonable RAID 5 array will have no trouble saturating that Gigabit Ethernet network you have at home in either direction, and let’s face it, if write performance were truly important, you’d be using solid-state disks!

At some point, though, the single disk’s worth of redundancy started to get worrisome. You have an increased likelihood of a disk failure during a RAID rebuild, because you’re probably going to be touching every sector on every disk. On top of that, as drives have gotten bigger the odds of hitting a spontaneous read error during the rebuild started approaching 100% when disks were just 300 or 400 GB.

Disks are ten times larger now, so you really want to have two disks worth of redundancy in each array—this really goofs up the math on my RAID 5 examples above, doesn’t it? This means you should be using at least RAID 6, RAID-Z2, or RAID 10.

My previous example isn’t so bad with Linux’s software RAID 6!

Let’s go back. You bought four hard drives, but you’re going to use RAID 6 or RAID-Z2. This means you’re giving up two drives’ worth of storage to redundancy in each array.

In the case of both RAID 6 and RAID-Z2, you’ll spend $400 on hard drives, and you’ll have 2 TB of usable storage capacity. In both cases, half of your storage is allocated as redundancy.

In two years, you decide to add another four drives, but this time they’re 2 TB at $100 each. If you’re running RAID-Z2, you can create a second RAID-Z2 pool. You will have 6 TB of usable storage, and half of your storage space will be allocated as redundancy.

If you’re running a Linux MD RAID 6 array, you can restripe across these additional disks, and you don’t have to buy them all at once. Just to keep it fair, though, lets say you did buy those same four additional 2 TB drives at $100 each.

Unless you rely on some fancy partitioning footwork, you’ll end up in roughly the same position. Linux’s RAID 6 implementation will ignore the second half of those 2 TB disks. You’ll have 6 TB of usable storage on your RAID 6 array, but you’ll have 4 TB sitting around. When you eventually replace the original four drives with larger ones, that space will become available.

What do you think? Should I write a blog post about that supposedly fancy partitioning footwork?

There’s too many made up prices

I’ve been adding drives to my arrays at home for decades, but before I had a blog, I had absolutely no record keeping. In the real world, things tend to be messier than this. When you start with four drives, at least one of them will probably fail before you need to upgrade to expand your array.

What do you do when a drive fails? I usually order a fresh drive from Amazon, then I wait for the manufacturer to process my RMA. That way, I don’t have to worry for too long about a degraded array. That also means I’ll have a spare disk in a few weeks, so I get to expand my array early!

That’s great, Pat, but what do these dollar figures look like in real life?

I am no longer the kind of guy that builds great, big NAS machines. There was a time when I stored a lot of data at home. My old desktop at home in 2001 had an 8-port 3Ware IDE RAID card and a stack of 30 GB IDE drives! Even after that, it was common for me to have a machine with at least six large SATA disks at home—my arcade cabinet has room for nine hard drives!

If you’re looking for a larger build, you need to talk to my friend Brian Moses. These days, my storage needs are rather small. When I built my Linux KVM virtual machine server for my office, I used a pair of 4 TB hard drives in a RAID 10 array for the bulk of the storage. You did read that correctly. It is a RAID 10 array with only two disks.

Flying FPV freestyle quads has resulted in a sharp increase in my data hoarding rate. If I had just left well enough alone, it would have taken at least six years for my DSLR photos to fill the storage on my NAS VM. I’m now accruing more FPV video every single month than I accrued in six years of shooting RAW photos with my DSLR!

This forced me into an early upgrade last year. This means I do have some real-world data!

In 2015, I bought a pair of 4 TB 7200 RPM drives for $140 each. That gave me 4 TB of usable storage for $280.

In 2018, I bought a third 4 TB 7200 RPM disk for $110. That brought my usable storage up to 6 TB for a total cost of $390. I know. That’s only a $30 savings! I wasn’t expecting to expand so soon, though.

Today, almost exactly one year later, I can buy an HGST 4 TB 7200 RPM disk for $72 with free one-day shipping. If I could have held out a little longer, I would have saved $70!

Who cares about $70? This is too much work for such a small savings!

I haven’t just saved money. If I had bought three disks in 2015, all my drives would be five years old today. That’s not the case, though. Two of my drives are five years old, and one is only two years old.

I’m on track to add a fourth disk in about 12 months. Assuming I don’t have a drive failure before then, I’ll have two six year old drive, one three year old drive, and a brand new disk. I start to get nervous when all the drives in my array are four or five years old!

Next year, the average age of the disks in my array with me 3.75 years, and by that time I will have saved at least $140.

What made you decide to use RAID 10? How can you have three disks in a RAID 10?

I didn’t need much storage, and I prefer to have two disks’ worth of redundancy. You can’t have fewer than four drives in a RAID 6 array. You can build a RAID 6 with a prefailed drive, and it will act like a RAID 5, but you still need three drives. At the time, I only needed about 1 TB of storage for my NAS and some extra scratch space for my other virtual machines.

I only needed two drives to build a RAID 10, and my virtual machines could benefit from the faster write speeds compared to RAID 5 or RAID 6.

I like to say that Linux’s RAID 10 implementation follows the spirit of the law rather than the letter. Linux’s RAID 10 implementation makes sure that each block exists on two disks—more if you want to be paranoid.

If you have two disks, Linux’s RAID 10 operates just like a RAID 1 mirror. You can lose either disk, and you won’t lose any data.

If you have an odd number of disks, like the three disks in my current array, Linux’s RAID 10 implementation will stagger your data. The first block will be on disks one and two, the second block will be stored on disks three and one, and the third block will be stored on disks two and three. With three disks, I can lose any single disk without losing my array.

In all cases, there are two copies of my data spread across array.

Things will be safer once I reach four disks. At that point, I will be able to lose up to two disks without data loss. Unlike RAID 6, which two disks I lose is extremely important! Your odds of surviving the loss of two disks in a RAID 10 increase with drive count. With RAID 6, you can lose any two disks without losing data.

Isn’t your cost per terabyte higher with RAID 10?

Yes, and the comparison will continue to get worse as my array grows. I appreciate the extra performance of my RAID 10 array, but I could definitely live without it. The biggest advantage for me was the up-front cost.

On day one, it cost me $280 to have 4 TB of usable space. Assuming I used 4 TB drives, and I would have, it would have cost $540 to have at least that much space available with RAID 6—only $420 if I cheated. I would have had double the usable space, but I didn’t feel this was necessary at the time.

Next year, I expect to have 8 TB of usable RAID 10 storage, and it will have cost me $460 or less.

As far as storage is concerned, at four drives, RAID 10 and RAID 6 would a tie. Starting with the fifth drive, RAID 6 would have netted me 50% more storage per additional drive. Because of the pair of SSDs in my home server, I can’t use more than four hard drives without adding a PCIe SATA controller. I’m going to do my best to avoid that anyway!

Calculating data growth, age of disks, and whatnot

When I was growing my RAID 10 last year, I was already thinking about writing this blog post. I even wrote up a quick and dirty script to help predict some useful information: how often you’ll need to add a new drive, how much each new drive may cost, how much money you’ve saved so far, and the average age of the disks in your array.

Drive Addition Predictor Output

My little Perl script is extremely dirty, and it isn’t nearly intelligent enough—that’s what happens when you spend less than 10 minutes on something like this!

I built in a concept something like depreciation. Each month, it assumes that a new drive will be slightly cheaper than the month before. I massaged that number to roughly align with my real-world experience, but that prediction will eventually fail.

4 TB drives will continue to drop in price right up until they stop manufacturing drives that small. Then the prices will start to slowly rise for a while. How do you build brains into the script to estimate when you should buy larger drives?!

I’m thinking about making the script a little smarter and converting it to Javascript. We’ll see if I ever get around to it!


I feel like this post rambled on longer than it should have, so I guess it is time for my tl;dr!

I prefer being able to purchase my storage as needed, at least here at home. It saves me some money. More importantly, it keeps my hard drives fresher. The drives in your NAS are spinning around 24 hours a day. They’re going to wear out. The odds of a drive failure increase dramatically in the fourth and fifth years of service. It is best to keep your hard drives as young as possible!

Most importantly, please remember that RAID is not a replacement for backups! RAID helps prevent downtime. RAID does not keep your data safe.

Do you run ZFS? Do you fill your NAS with disks when you build it, or do you add storage as needed? Do you just hope to win one of Brian Moses’s NAS builds that is already stuffed full of hard drives? Tell me about it in the comments, or stop by [our Discord server][bw] to chat!

Can You Run A NAS In A Virtual Machine?

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Of course you can. There is absolutely nothing stopping you. My home NAS is running in a virtual machine.

Should you host your NAS as a virtual machine? I don’t know anything about your needs, but I bet you can get away with running a NAS in a VM. It is definitely the correct option for my use case!

Some folks will tell you that running your NAS in virtual machine a terrible idea. I’m going to tell you why they’re wrong, and I’m going to help keep you from making mistakes that would make those people correct!

What a is a NAS?

The acronym stands for Network-Attached Storage. In the old days, We used to call them file servers, but I guess that just wasn’t fancy enough. Anything that shares files on an IP network qualifies as a NAS. In the old days, we even used IPX, but we didn’t use the term “NAS” back then.

Some of Brian's NAS builds

Your cheap Wi-Fi router with a USB flash drive plugged into the back. Your old Windows XP laptop that’s sharing all your movies. My own virtual server running Samba on Linux. My friend Brian’s beefy DIY NAS servers and his EconoNAS boxes. They’re all network-attached storage devices!

What isn’t a NAS?

A NAS doesn’t transcode video. A NAS doesn’t have to be using ZFS. A NAS doesn’t require ECC RAM. A NAS doesn’t host virtual machines. A NAS isn’t an iSCSI target—that’s a SAN!

Running extra services like a video transcoder, iSCSI targets, or virtual machines will make your server more versatile. They aren’t part of the NAS.

But what if I want to run Plex on my NAS?!

That’s fine! A NAS server is just a file server, and a file server is just a computer. You can do whatever you like with your computers.

You want to host VMs on your server? Go for it! Just make sure you have enough RAM and CPU to handle the load of those virtual machines.

A NAS doesn’t need much processor power or a ton of RAM—your Gigabit Ethernet or Infiniband connection will be your bottleneck most of the time. Transcoding video doesn’t require much RAM or disk, but it sure does need a lot of CPU.

This is exactly the sort of use case where virtualization excels. Your NAS isn’t making much use of your processing power, and your Plex transcoder isn’t fully utilizing its disk or RAM. If you put them both on the same box, you’ll make better use of your hardware.

Some of my virtual machines

Why virtualize each service? Why not put the NAS and Plex server on the same machine?

Plex communicates with services on the Internet. That’s enough reason for me to want to keep my file server separate from Plex. I want Plex to be able to see my videos. I don’t want my bank statements or drafts of my upcoming blog posts leaking out to the Internet!

Am I building a NAS that transcodes video, or a transcoding server that serves files?

This is almost a silly question. You might use a truck to haul plywood home from Lowes. You might use a minivan to drive your family to the arcade.

You can pack your family into the pickup truck, but you might only have those goofy little fold-down seats in the back. You can haul plywood in your minivan, but you’re going to have to fold down or remove the seats.

Each can do the job of the other. Your preference will be based on which task you do more often. If you’re hauling six kids around every day, you want the minivan. If you’re running to Home Depot three times a week, you’ll want a truck.

These are two options that can handle two very different jobs. Maybe you don’t have six kids, and you never bring plywood home from Lowes. You don’t need a large vehicle. Maybe you’re like me, and you only need a Miata.

Sharing files to a handful of computers at home doesn’t require much CPU or RAM. It doesn’t require a truck or a minivan. You can build a little Atom or Celeron machine that sips power and doesn’t cost much.

If you need to transcode video on demand, you’ll be looking at entirely different motherboards and processors. You’re going to be looking at trucks or minivans. Are you building a NAS that also transcodes video, or a beefy transcoding machine that happens to serve files?

I don’t know which server is the truck or the minivan. I’m sure you get the idea.

QUESTION: The streaming devices on every TV in my house can play back 4K content using all the common codecs just fine, and buying three or four of those is cheaper than the CPU it would take to transcode. What on Earth is everyone transcoding?!

Everyone says I should run ZFS on my NAS!

I agree with them. Running ZFS on a NAS is a fantastic idea. ZFS computes and stores checksums of all your data. When ZFS reads your data back from the disk, it compares the data to the checksum. If it doesn’t match, it knows your data is corrupt.

If ZFS is able to read that same data from a different disk, it can correct that error. Standard RAID levels won’t even detect that kind of error, so they can’t correct for it.

Ryzen 1600

ZFS isn’t the only file system option with checksums, but it is one of the best and most advanced. The Linux kernel’s device mapper layer now has a module called dm-integrity, and I’m interested in trying it out. It adds a ZFS-like checksum layer to any block device.

I have a feeling that I’ll have to tear down the RAID 10 on my KVM server to set it up, and I’m not excited about putting in that work!

Redundancy is important

Earlier in this post, I said that all you need for a NAS is a USB flash drive. That may qualify as a NAS, but it would be a pretty terrible file server!

Hard drives fail, and they fail often. Backblaze’s data says that 5% to 10% of their hard drives fail every year.

RAID is not a replacement for backups

RAID prevents downtime. If you don’t have hot swap bays in your server, you will have to take your server down to replace a dead hard drive, but at least you don’t have to go through the time and pain of a restore from backup.

RAID won’t save you from a lightning strike. RAID won’t save you when a bad SATA controller mangles all your disks. RAID won’t save you when your file system gets corrupt. RAID won’t save you when you accidentally delete something. RAID won’t save you from malware.

ZFS has some nice features that can mitigate some of these risks. Regular snapshots will probably protect your from malware and accidental file deletions, but not much else.

It is fairly common to have a second drive in an array fail as you are replacing a disk. Rebuilding a RAID requires reading every bit of data from each drive, and it can take quite a few hours for the process to complete. This can be stressful for a drive that is already near the end of its life.

Storage is cheap. Backups are expensive. Have you ever wondered why your IT department wants to limit your storage space and the size of your inbox? Adding a few more disks is cheap. Backing up all your data and sending it off-site every single day is expensive!

Wait a minute! If ZFS is so great, why aren’t you using it on your NAS?!

I set up my NAS virtual machine almost five years ago. My NAS is running Linux, and at that time, ZFS support on Linux wasn’t so great. Ubuntu had only just started shipping native, in-kernel ZFS support at that time. I’d already used the ZFS FUSE file system on another machine, but it didn’t perform all that well.

I am not a fan of FreeBSD, and I have no need for the FreeNAS’s convoluted web interface—I work much faster at the command line. Plenty of people use FreeNAS, and I’m sure I could have run it in a VM.

ZFS combines many of the features of Linux’s separate MD and LVM layers. This makes ZFS powerful and convenient, but ZFS is currently missing an important feature.

You can’t add disks to an existing ZFS zpool. If you want to expand your storage, you have two choices. You can replace every single disk in your zpool, but this can be expensive. You can create an additional zpool, but if you’re using RAID-Z2, you’ll be wasting two more disks’ worth of space on redundancy.

Linux’s MD and LVM layers allow me to easily add additional disks to my RAID 10 or RAID 6 arrays. When I run out of space, I just buy another drive.

ZFS was created by a company that sells expensive, high-end servers. Every time it has been my job to spec out servers in a data center, I almost always filled the chassis with disks. That’s exactly what Sun expected their customers to do.

If you’re spending your own money, there are plenty of good reasons wait until you actually need more storage before buying more drives. Prices decrease over time, and the older a drive gets, the more likely it is to suffer a mechanical failure.

Which device should host my NAS?

I like to consolidate my services as much as possible. Also, I’ve always encouraged people to run their in-home services on hardware that already needs to be powered on all day long.

For a long time, I hosted my NAS and other virtual machines on my arcade cabinet. My NAS needs to be accessible 24 hours a day, and having my arcade cabinet ready to go at a moment’s notice was awesome. Why waste 30 to 60 watts on two different machines that are usually idle?

You probably don’t have an arcade cabinet.

I needed to get my NAS VM closer to my desktop, because CX4 cables for Infiniband aren’t very long!

Does my NAS virtual machine need its own RAID?

I had about four different headings here with about 1,500 words explaining the advantages and disadvantages of various RAID configurations. It was dry, boring, and probably not all that helpful. Instead, I’m just going to tell you what I do, and why I do it.

On my own setup, my virtual machine host has a RAID 10 array with LVM configured on top of it. Some of my machines use LVM block devices on that RAID 10 array as disks, but most of them use disk image files that are stored on an ext4 volume on my RAID 10. I take a performance hit by using image files, but they tend to be more convenient than block devices.

Parts for my KVM server

My virtual machines don’t need any RAID configuration. All the disk redundancy work is handled by the host. The less specific the virtual machines are to the host, the better. It makes it easier to shuffle machines around.

If a drive fails, or I expand my storage, the virtual machines will be completely unaware.

The RAID 10 array on my KVM server is encrypted. If someone pulls the plug and carries the box out of my house, they won’t be able to access any of my virtual machines. With this setup, I don’t have to enter a passphrase into each VM when they boot up. I only have to unlock one encrypted volume when the KVM server boots up.

Is there any reason to set up your RAID in the NAS VM?

Yes. If you’re running ZFS or dm-integrity on the host, and there is a checksum or read error, your NAS virtual machine will never know about it. ZFS may tell you that it corrected an error, or it may tell you that there is a file with a bad checksum, and it can’t fix it.

Which file has the bad checksum? If you are running a set-up like mine, you’ll have to do a lot of work to find out. ZFS would tell me that there was a checksum error in the disk image file of my NAS VM. ZFS on the host doesn’t understand what’s inside that image file, and the NAS VM may have no idea that there was an error.

If the error can be corrected, ZFS or dm-integrity will correct it. This will be the situation most of the time. If you’re starting to lose data to irrecoverable errors, you’re already in big trouble anyway, and it may be time to test your backups.

How do I set up a RAID or redundant zpool in a virtual machine?

Very carefully. Remember when I said there are reasons people will tell you it is a bad idea to run a NAS in a VM? If you set up your RAID inside the VM, and you make a mistake, you will greatly increase your chance of data loss!

You have to make sure each virtual disk is pointed at a different physical disk in your server. You have to make sure that your virtualization software makes your virtual machine’s connection to the disk as direct as possible. It isn’t difficult, but you have to be meticulous. If you goof up, you can make things extremely fragile!

ZFS needs to be as close to the disks as possible. You don’t want the host doing any caching. You don’t want the host absorbing any read or write errors. iXsystems has a post about how to run FreeNAS with ZFS in a virtual machine, and it explains the various pitfalls.

I’m still going to say that you should follow my lead and set up your old-school RAID or ZFS on the host. Unless you have a really good reason to have the VM do this job, I doubt it will be worth the hassle for you.

What does Pat store on his NAS?

I store data that doesn’t comfortably fit on the SSD in [my desktop computer][]. For the most part, that is the RAW files produced by my DSLR and FPV flight footage.

A lot of people use their home NAS to back up the data on their computers. I prefer my backups to be off-site. I use Seafile to meet both my file syncing and backup needs. Seafile is an open-source Dropbox equivalent. It keeps all the data on my desktop and laptop in sync, and 90 days of file history are stored on the server. All the data on the server is encrypted on my end.

If I need to restore a file, it will be on the Seafile server. If the SSD in my desktop fails, I have a recent copy of that data on my laptop, so I don’t have to wait for everything to download. I’m quite pleased with the functionality, redundancy, and cost of this setup.

The only important data on my NAS that isn’t backed up is the GoPro footage of my FPV freestyle flying. The volume is huge, and the older it gets, the less value it has. The footage I collect each month is nearly as large as the collection of photos I’ve taken with my DSLR over a four-year period—200 to 250 GB.

Storage on my NAS is rather inexpensive, so I don’t yet feel the need to delete any of the old footage. That said, I’m extremely unlikely to rummage through flight footage from two years ago. Most of the footage is mundane. Finding 20 seconds of interesting footage among 45 minutes of a day of flying is tedious.

I could be served nearly as well if I just threw a large hard drive into my desktop computer.

Do you have any advice on building a NAS server?

I’m so glad you asked! I wrote an article listing a bunch of tips and general rules of thumb to help you out when you’re building your own NAS server, and I posted it over at Butter, What?!

With any luck, my tips will help you decide if your network is fast enough, whether your disks will be fast enough to keep up with that network, and how to choose hard drives. I hope it will be helpful for you!


Everyone’s needs are different. Sharing files is the least important job handled by my little homelab server. Adding disks to my KVM box to supply storage space for my NAS VM was inexpensive, and it adds less than 10 watts to my overall power consumption.

I don’t see a need to invest the money, electricity, or time into setting up and running a separate piece of hardware to store my large files.

How are you handling your file-storage needs? Do you have a dedicated, beefy NAS machine like the ones my friend Brian Moses builds? Did you win one of the NAS servers he’s been giving away over the years? How are you handling your backups? I’d like to hear about it in the comments, or you can stop by our Discord server to chat with me about it!

The Kestrel HD Micro Quad Frame Version 1.0

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I’m excited. I started working on my open-source HD micro frame roughly two months ago. Since then, I’ve assembled a Shapeoko XXL CNC machine, learned how to use the machine to cut carbon fiber, and I’ve flown several iterations of my frame design. I’m certain that there will be more changes to come, but I am quite pleased with the design so far, so I’ve decided to slap a Version 1.0 sticker on it!

My current build is using EMAX 1306 4000 kv motors, and it weighs 223 grams with a 650 mAh 4S pack. I usually get around 5 minutes of fairly aggressive freestyle out of it.

My friend Brian transplanted his Diatone GT-M3 to a Kestrel frame. With his HGLRC 1407 motors, he’s coming in at 253 grams with the same battery. He’s a bit over the 250 gram limit, but not by much!

The Kestrel is licensed under the GNU GPL 2

I planned for the Kestrel to be open source from the beginning, but which license should I use? The choice of license was actually quite simple. I borrowed an awesome fillet function for OpenSCAD from Github, and that fillet function was licensed under the GNU GPL.

Since I wanted to include that function in my source code, I had to license it under the GNU GPL 2 as well.

My 3-inch Kestrel

There aren’t a lot of open-source FPV quadcopter frames to choose from. The most popular would be the TBS Source One frame. How does releasing an open-source frame help you?

If I stop manufacturing frames, you could still acquire spare parts from someone else—I haven’t even figured out how to manufacture or sell these frames! If you have access to a CNC machine, you can cut your own. I wish CNC machines were as readily available as 3D printers!

If the source code is available, won’t that make it easier to clone the Kestrel?

Yes, it will, but only slightly. Copying a frame is extremely easy. All you need is the piece of the frame and a scanner. Almost anyone could pull it off.

I am much more excited about giving you the ability to cut your own frame than I am worried about someone selling copies of my design!

What can I do with the source code?

The Kestrel is designed using OpenSCAD. OpenSCAD is an open-source CAD package. Instead of creating your objects by dragging and dropping various shapes and operations around the screen with your mouse, everything is defined using OpenSCAD’s programming language. Everything is built from unions and differences of basic shapes like cubes, spheres, and cylinders.

If you’re a programmer, this may be easier for you to handle than a traditional CAD package. OpenSCAD excels when you need to build objects that match precise measurements. You’ll start to get into the weeds when you try to model more organic shapes.

Early model of the Kestrel's motor mount

Modeling in OpenSCAD requires more work up front, but it can pay off in the long run. The most time-consuming task when creating the Kestrel was getting the guitar-shaped motor mounts right. The mounts are built up using a configuration of hulls and fillets of a variety of discs.

The diameter and spacing of those discs is based on the distance between the motor’s mounting holes. The entire mount had to work well with the 9 mm hole spacing of an 1106 motor up to the 16 mm hole spacing of a 2207 motor. Getting the ratios and angles correct to make either extreme look right was challenging!

I think it was worth the extra work. There are quite a few important parameters of the frame that can now be adjusted by simply adjusting the measurements in variables at the top of the OpenSCAD source code.

  • Motor mount hole spacing
  • Arm length
  • Arm angle
  • Arm width
  • FPV camera’s protection diameter
  • FPV camera’s relative positioning
  • Side plate thickness
  • Height available to the stack
  • Grommet hole length and height
  • Grommet tab depth and width

Do you want to build the tightest 2.5” HD micro quad? You can punch new measurements into two or three variables, and you can get the props as close to each other and the fuselage as you’d like.

Some of the Kestrel's variables

My 3” configuration pushes the motors out just about as far as they can go. If they were much longer, I would have had to extend my motor wires. Longer arms help deliver clean air to each propeller, and the extra leverage makes the quad more stable.

Do you want to fly a spindly, lightweight 6” HD quad? You could easily cut some crazy arms for the Kestrel, and I am more than a little tempted to try this!

The bushings probably need tweaking

Are they bushings or grommets? McMaster-Carr calls them grommets, but I seem to keep changing my mind.

This is the part of the frame that I need to get right. The Acrobrat comes with three different sets of bushings with various hardness ratings. McMaster stocks an appropriate bushing, and a 100 pack was less than $10. I didn’t get to choose the stiffness, though. They’re rated at a shore hardness of 55. That’s pretty close to the medium-stiffness bushing that ships with the Acrobrat.

The Kestrel's suspension

I can’t modify the stiffness, but I can adjust how tightly the grommet fits over the tabs on the bottom plate. My first prototype was too tight. I don’t even think the rubber was loose enough to absorb any vibration at all!

I’ve loosened it up quite a bit. I made the tabs narrower, and I made the oval-shaped grommet hole in the side plate a bit taller. There’s a good bit of play in there now—hopefully not too much!

I’m going to try a 4” build!

The 3” version of the Kestrel is flying quite well. I’ve had some trouble with my 1306 build, but I think I’ve gotten it mostly under control—I hope! Brian’s 1407 build is flying great, even though he didn’t quite manage to fit under the 250-gram limit—not that he has any need to!

The new arm interlocking system

I’d like to order some parts to build a lightweight 4” quad. I’m having a hard time choosing hardware. I like the EMAX 1606 3300 KV motors, but choosing a 20x20 stack is difficult!

The motors aren’t much heavier than my 1306 motors, and longer, thicker arms will only add about five extra grams. I’m hopeful that my build will fit in under 250 grams, but I won’t be too upset if I exceed that weight.

It has been two years since I flew a 4” quad. That old 4” quad had 2204 2750 KV motors. I’m hoping that the difference between a heavy 3” build and a light 4” build feels a lot like the difference between a 5” and 5” quad. It should have more bottom end, so it will be easier to catch the quad when falling out of a dive. It should also be more efficient, so I’m expecting to get longer flights. It will probably be less responsive, but the 3” almost feels twitchy to me, so that might be a bonus!

If the 4” build flies well and fits in under 250 grams, I think it will be an interesting build for the parts of the world with serious weight restrictions!

Motors are easy. Finding a 20x20 stack that I like is hard!

There are a few problems with moving to 4”

Tiny boards for 2.5” and 3” micros are plentiful. 4-in-1 ESC boards that can properly handle larger motors and props are somewhat larger, even when they use the 20x20 mm mounting pattern. They also tend to require M3 screws instead of M2 screws.

I can just drill larger holes in my central stack and call it a day, but I have a better plan. I’ve ordered some tiny grommets from McMaster-Carr. If I measured correctly, these grommets should work well for soft mounting a stack that requires M2 screws. The hole these grommets fit into should be just about the right size for an M3 screw, so these will allow for either configuration using the same mounting holes.

I’m looking at two stacks. The Lumenier MICRO LUX V3 stack and the Aikon AK32PIN stack.

These are both 20x20 stacks that require M3 screws. They’re both F4 flight controllers with blheli_32 ESCs. The Aikon ESC is quite a bit larger, but it is capable enough to be used in a 6S 5” miniquad. The Aikon ESC alone costs as much as the Lumenier stack.

The Aikon ESC will be a tough fit, but it looks like I can squeeze it in. If I do go this route, and fitting such a large ESC is too difficult, I will probably adjust the length of the fuselage to compensate. Am I going to be moving past version 1.0 this quickly?

The source code is hosted on Gitlab

The OpenSCAD source code, a simple build script, and SVG and DXF output files for several arm configurations are being hosted on Gitlab.

There are configurations for two sets of 3” arms, one set of 4” arms, and a ridiculous set of 6” arms. Only one set of 3” arms has been flight tested. All the 3” and 4” arms are built by the build script, and the SVG and DXF files to cut those frames are in the output directory. I left the 6” arms out of the build script, because they’re just crazy.

What makes the Kestrel unique?

I wanted to build a 3” Acrobrat, but I don’t think the Acrobrat is the frame for me. I wanted to use 1106 motors, and I wanted to keep the weight down. The Acrobrat is a big, heavy frame. I believe it comes in at 54 grams with all the hardware. I hoped I could build something more appropriate for my own needs, and I think I’ve done a reasonable job!

Brian's 1407 Kestrel

The Kestrel uses individual, replaceable arms. Those arms are easily configurable, so it should be possible to run anything from extremely short and tight 2.5” props on 1106 motors, 5” props on 2207 motors, or anything in between. Each arm is held in place with a single screw, so they are easy to replace in the field.

The arms are positioned to keep the props completely out of view of the HD camera.

I wanted to fit three 20x20 stacks, just like the Acrobrat. Having all that space makes it so much easier to build and repair your micro quad. In addition to room for three stacks, the M3 screws for the motors also line up with a standard 30.5x30.5 stack.

The Kestrel uses a suspension system like the Acrobrat’s. The weight of the battery and HD camera are separated from the vibrations of the motors by rubber bushings.

My 3-inch Kestrel

A Kestrel frame with long 3” arms currently weighs 39 grams. That’s about 15 grams lighter than the Acrobrat. I’m quite certain the Acrobrat is sturdier, but I’m hopeful that the Kestrel is just sturdy enough! Time and crashes will let us know for sure.

How do we keep Pat working on open-source frames?!

I’d love to tell you to buy a frame, but selling frames isn’t easy—especially if you’ve never done it before!

I’m just barely beginning to investigate having 3” Kestrel frames manufactured. There’s no shortage of companies in China that will do this sort of thing for you, and it seems inexpensive—even for fairly small batches! I’m more than a little worried about attempting this, but if there’s enough interest, I’ll do what I can to have frames manufactured.

Carbon fiber 3mm

I plan to at least offer a limited quantity of 3” Kestrel in my store on Tindie. If you’d like to buy a Kestrel, you can always get in touch with me, and I’m sure we can work something out. I don’t even know how much I should charge!

If you think I’m doing interesting work, and you’d like to see me continue, you can always become a Patron. A few dollars a month goes a long way towards carbon fiber, replacing dull end mills, and helping me recoup the cost of the CNC machine.

I’ve probably already gone through $50 to $100 worth of carbon fiber sheets on test parts. Every tweak to the frame eats $5 to $10 worth of material, and after two or three frames, I need to throw away a dull end mill. The costs add up fast!

You can also help me out on Youtube. Subscriptions are awesome. Comments are even better. More eyeballs on the Kestrel will make it easier for me to work out manufacturing!


I’m excited to be contributing an Open-Source FPV quadcopter frame to the community. I wish CNC machines were as prolific and available as 3D printers, but I’m still hoping someone will be interested enough to cut a frame for themselves!

I’m starting to send frames out for testing. If you’re interested in testing the Kestrel, feel free to get in touch with me. I’m planning on sending some out for not much more than the cost of the carbon and shipping. Does it count as selling if I’m losing money?

Are you flying an Acrobrat? Are you flying a different HD micro frame? Have you been hoping for a lighter Acrobrat-like frame with replaceable arms? I’d love to hear about what you’re flying! You can leave a comment below, or you can stop by our Discord server and chat about it!

My First Week With The DJI Osmo Pocket

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When the early reviews of the DJI Osmo Pocket started showing up on YouTube, I was disappointed in what I saw. The microphone sounded worse than what I get out of my $150 Android phone, and much of what should have been core functionality was relegated to add-on hardware. The Osmo Pocket costs $350, then DJI wants to nickel and dime you to add more physical controls ($59), Bluetooth and Wi-Fi ($59), a mic input (not available yet), and even a tripod adapter ($19).

A nifty $350 video camera quickly becomes a $500 camera. At that price, you can start looking at cameras like the Panasonic Lumix G7. I’m well aware that these two cameras are like apples and oranges, but I can’t be the only one who could have their primary requirements fulfilled by either camera!

DJI fixed the problem with the microphone, but I’m still displeased with the plethora of unnecessary add-on hardware. How much bigger would the Osmo Pocket need to be to squeeze in a threaded insert for a tripod, a mic input jack, and a Wi-Fi chip?

I haven’t had the Osmo Pocket long enough to get much use out of it, so this isn’t going to be an in-depth review. I’ll be talking about the specs, how it compares to my Zhiyun Smooth 4 and the less-expensive Tzumi SteadyGo gimbals.

So why on Earth did you buy an Osmo Pocket?

I had a minor calamity, and it was an embarrassing one. I was out in the garage running my Shapeoko CNC machine. Its Dewalt router is quite noisy, and I was in the process of vacuuming up all the carbon fiber dust. I accidentally sucked something up into the vacuum, so I had to move myself over a few feet to shut off the vacuum and disconnect the hose.

I stepped on something, and my foot started slipping. What did I step on? My cheap Android smartphone! It was screen down, and it was quite slick. The screen cracked. I don’t even remember bringing the phone to the garage with me!

This is embarrassing, because I’ve been carrying a smartphone since the Palm Treo 650, and I’ve never broken a phone. I had a flash chip go bad once, but I’ve never physically damaged a phone like this.

I was using that phone with a Zhiyun Smooth 4 gimbal. The Smooth 4 has been fantastic, and it is what I’ll be comparing the DJI Osmo Pocket to. The phone’s camera was just barely good enough, but it did the job.

I stepped on a phone, so what do I do? Replace it with a phone with a better camera and continue using the Smooth 4? Or should I pop my SIM card back in my previous phone and try out the Osmo Pocket?

You already know what I chose to do

The Osmo Pocket does many of the things that my Smooth 4 can do. They both offer face and object tracking, they can both record motion timelapse video, and they both have similar stability modes. The Smooth 4 has some interesting focus pulling features, but that feature didn’t work on my oddball phone.

The Osmo Pocket has a better camera and microphone than my cheap Blu Vivo 8, and the form factor is a huge upgrade—the Osmo Pocket is a fraction of the size!

The form factor of the Osmo Pocket is awesome!

I’m good at sitting down at my desk and writing. I’m trying to do a better job of uploading content to YouTube, but I have been failing. My hope is that the convenience of the Osmo Pocket will encourage me to carry a video camera more often, and also to talk to the camera more often.

You’d think I could manage to at least talk to my phone’s camera once in a while, right? It never works out, though. Holding the phone up to “vlog” isn’t comfortable or steady without a small tripod, and it is amazing how difficult it is to open the camera app, flip to the front camera, switch to video mode, and start recording when you only have one free hand.

The Zhiyun Smooth 4 makes it easy to hold the phone up when you’re talking to the camera, but I never have it with me. It is way too large.

The Osmo Pocket is tiny. In its carrying case, it fits safely and comfortably in the same front pocket as my phone. I am sometimes aware that it is there while sitting down, but it isn’t much of an annoyance. I can carry this thing for eight hours without any trouble.

Recording myself or others with the Osmo Pocket is easy, too. It is light, so it is easy to hold it high enough that you don’t have to look up my nose while I’m talking to the camera. The camera’s field of view is reasonable for this mode of operation, and its face tracking does a good job of keeping me in frame.

The Osmo isn’t just an upgrade for recording myself. It is a big upgrade over holding a smartphone when recording video in front of you as well. Holding the camera like a pistol is easier and more comfortable than holding a thin rectangle, and the stability of the gimbal makes your shots look more professional.

The best camera is the one you have with you

I love my Canon 6D DSLR. It is a fantastic camera for photography, and it is capable of capturing amazing video. It is getting old, and Canon has always been behind when it comes to video. The Canon 6D has no autofocus while recording video, and the thing weighs nearly three pounds with my favorite lens attached.

If the subject is going to be standing still, and I have time to set up a tripod and a mic, my Canon 6D will easily out-perform the Osmo Pocket.

My Giant Canon 6D

I can’t carry my three-pound DSLR everywhere I go, but I can keep that Osmo Pocket on hand all the time. I can pull it out of my pocket and be recording video in less than five seconds.

Whoever said this is absolutely correct. The best camera is the one you have with you. Especially when it is convenient enough to use!

3D-printed accessories for your Osmo Pocket

I’ve been 3D printing for a long time, so you can probably guess what the first thing I did after placing my order for an Osmo Pocket was—I stopped by Thingiverse to see if there were any things I needed to print!

There’s no shortage of stands and tripod adapters for the Osmo Pocket on Thingiverse. I chose an Osmo Pocket stand that combines both into a single device, and it is working quite well.

UPDATE: I’ve designed and uploaded a combination tripod adapter, stand, and case for the Osmo Pocket to Thingiverse!

I’ve also designed my own adapter based on that same object. It isn’t elegant or clean, but it is getting the job done.

Shortly after the Osmo Pocket arrived, I took it out to the car and tied it to my smartphone holder. I was impressed with how well it managed to record me while I was driving. I expected to hear a lot of road noise or the engine, but it sounded just fine!

Using a Velcro strap to hold the Osmo Pocket in place every time I get in the car was going to be the opposite of quick and easy, so I decided to throw a quick design together. It isn’t anything fancy. Just a rectangle attached to the stand I had already found on Thingiverse. The Osmo goes in the stand, then the stand fits into the car mount just like a smartphone.

I should mention one other accessory that I’m using, even though I didn’t 3D print it. I had to buy it. It is an extendable selfie stick tripod. It wasn’t too difficult to find, but the majority of these types of tripods have phone clamps on the end instead of ¼-20 threads.

I bought this tripod mainly for recording video at my desk. All my small tripods are too short to get the Osmo Pocket up to eye level. This extending tripod folds up as small as my old mini tripod, but it can also extend all the way to 40”.

You shouldn’t use it as a tripod at that length, because it will definitely tip over and smash your fragile Osmo Pocket. I extend it to 12” to 15” at my desk when recording my own ugly mug.

Connecting your phone to the Osmo Pocket

You have to connect your phone to your Osmo Pocket at least once to activate the device, and again any time you need to update the firmware. I had to buy an adapter to plug the USB-C output into my old Blu Vivo XL2. The DJI MIMO app works fine with this adapter.

I don’t have any plans to use their app when recording with the Osmo Pocket. I’m excited about having a tiny camera that I can fit in my pocket. I don’t want to make it bigger. I don’t want to waste time plugging devices together and opening apps. I just want to pull the camera out and start recording!

The app was almost required before the recent firmware update. Today, you can access almost all the features and settings of the Osmo Pocket from its tiny touch screen. It can be a bit fiddly, but it works.

The GoPro HERO7 Black and the Samsung Galaxy S10+

For my use case and budget, I’m happy enough with my choice, but there are alternatives that will capture video every bit as smooth and steady as the DJI Osmo Pocket.

The GoPro HERO7 Black has an option called Hypersmooth, and it is quite impressive. Footage recorded with Hypersmooth looks an awful lot like it was recorded with a gimbal, and the HERO7 Black doesn’t cost much more than the Osmo Pocket. If you’re interested in pointing the camera at yourself, the GoPro’s lack of a front-facing display will be problematic.

The Samsung Galaxy S10+ has optical image stabilization on the rear camera, and it has a feature similar to GoPro’s Hypersmooth. I’ve seen some footage on the Internet, and it is quite impressive. I’m not sure if you can use that feature on the front-facing camera. The price of the Galaxy S10+ is several times that of the Osmo Pocket, but it is way more than a camera.

There are a few features you’ll miss out on by using a phone or action camera instead of a gimbal, but I’m not sure how compelling those features are. You won’t be recording a motion timelapse or doing any face and object tracking without a gimbal.

The Galaxy S10+ is the only phone with stabilization on par with the Osmo Pocket today, but that won’t be true for long. How many years will it be before $200 Android phones are competitive with Hypersmooth? The Blu Vivo 8 that I stepped on had a pretty reasonable anti-shake feature. Who knows where things will be in two more years?

A gimbal for your phone may be a good option, but it isn’t for me

Last year, I bought a Zhiyun Smooth 4 gimbal for my phone. It works great, and it is a lot of fun to use. It has many of the same features as the Osmo Pocket, but it is available for about a third of the price. You probably already have a phone with a decent camera, so that’s all you would need to buy.

A few months ago, my friend Brian bought each of us a Tzumi SteadyGo gimbal. had a deal, and they were only about $30 each. They’re currently around $70 at Amazon—only a fifth of the price of the Osmo Pocket! The reviews are rather poor. They seem to fail a lot.

I’ve only used mine a few times, but it seems to work about as well as the Smooth 4 gimbal. Basic gimbal functions work great, and face and object tracking seem to work fine.

There are two big advantages that these gimbals have over the Osmo Pocket, and one huge problem. Smartphone gimbals cost a lot less, and you can upgrade the camera. Every time you buy a new smartphone, you’ll be getting a free camera upgrade.

Unfortunately, both of these gimbals are huge. They’re about twice as tall as your smartphone and quite unwieldy. You won’t be putting either of these two gimbals in your pocket.

You can pull the Osmo Pocket out of your pocket, take it out of its case, and have it recording in five to ten seconds. The only way to get up and recording that quickly with the Zhiyun or Tzumi gimbal would be by having the gimbal powered up in your hand the whole time.

My Zhiyun and Tzumi gimbals are going to be spending a lot of time in the closet now, but I expect I’ll be pulling them out of the moth-balls in about two years! Those phone cameras just keep getting better.


So far, I’m pleased with my purchase. It would have been nice if DJI made the Osmo Pocket just a little bigger. I would have liked to see the jog wheel, Wi-Fi, and Bluetooth included in the base device. Adding a tripod mount and mic input wouldn’t have required much more space, either.

Even without these features, I think the DJI Osmo Pocket is worth $350. I’m infinitely more likely to be carrying the Osmo Pocket than either of my phone gimbals, and having quick access to the Osmo means I’m that much more likely to be filming. I need to be filming so much more often!

Do you have a gimbal for your smartphone? Are you regularly using Hypersmooth or a Galaxy S10+? Have you tried the Osmo Pocket? Let me know what you think in the comments!

Caddx Turtle or Runcam Split vs a GoPro on FPV Freestyle Quads

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I’ve been carrying a micro FPV quadcopter in my bag for quite a while. I started with a KingKong 90GT, then made a huge upgrade to a Full Speed Leader 120, until finally making the minor upgrade to a Leader 3. These micros were always an afterthought for me.

Micros don’t fly as well as a 5” miniquad. They’ve been getting better quickly, though! The hardware has been improving, and so has the software. The gap between 3” and 5” FPV quads hasn’t completely closed, but it isn’t the chasm it was just a couple of years ago!

I still like having one in my backpack, even if they don’t fly as well. They don’t weigh much, and they don’t take up much space.

That performance gap is closing, and I bought a CNC router this year. Designing a spacious 3” micro quad with vibration damping seemed like it would be fun! That means it was time to try out one of these FPV cameras with a built-in HD recorder.

This blog post isn’t going to tell you how to get the best footage out of your Runcam Split—I haven’t been flying long enough to figure that out yet! I am going to tell you why I think there are times when you might want to settle for the footage from a Split or Turtle.

The Caddx Turtle V2 always makes me miss my GoPro HERO5 Session!

I didn’t have a terribly compelling reason for choosing the Caddx Turtle over the Runcam Split Mini 2. The footage straight off the Turtle seemed marginally more tasteful to me, and I remembered not having a good time getting the original Runcam Split Mini into Brian’s 3” micro last year.

As far as I can tell, there’s little difference in the video output of these cameras.

Every time I get home and look at my footage, I wish the Caddx Turtle had GoPro’s Superview. Everything looks so goofy and fish-eyed through the lens of the Turtle. This looks worse the farther the horizon gets from level. Near the top of a power loop, the horizon will be curved to a ridiculous degree.

The overall quality of the video isn’t the best, either. You can tell that the Turtle’s video files aren’t matching the bitrate of the GoPro, especially when you’re flying fast!

I believe using an ND filter on the Turtle would address some of my complaints. I’m planning on trying this out sometime!

Why the heck would I fly with a Caddx Turtle or Runcam Split if the GoPro is so much better?

If I weren’t in the process of designing a 3” HD micro frame, I might have already given up on the Turtle. Getting smooth video out of the Turtle is a challenge, especially on a 3” quad. My 680-gram 5” freestyle quad is almost always smooth, and 15 MPH winds don’t push it around all that much.

I feel there are at least two extremely compelling reasons to use a Caddx Turtle on a 3” micro quad: cost and safety.

The components I used to build my 5” freestyle quad cost about $550. They don’t make my GoPro HERO5 Session anymore, but mine cost about $200. The full-size GoPro HERO6 Black costs $279. A battery costs about $25. That means I have $750 to $830 in the air every time I fly; even more with a GoPro HERO7 Black!

My Leader 3 cost me about $120. The Caddx Turtle costs $65. It is tough to put a price on the Kestrel frame I cut for myself, but let’s just call it $35—that’s $10 less than an Acrobrat. Batteries for the little guy cost about $12. When I fly the Kestrel, I have less than $250 in the air.

That’s $250 for everything in the air: the quadcopter, the battery, and the HD camera. That’s less than the cost of a GoPro HERO6 Black. The only way I know of to make that GoPro fly for free is by throwing it!

If I want to capture some FPV footage in a spot where I might lose my quad, I know exactly which one I’m going to be flying!

Are these really the only two options?

Of course not! You can definitely build a capable freestyle miniquad for less than $550, and there are less expensive camera options. Foxeer and Runcam have made some reasonably priced action cameras.

You can still get refurbished GoPro HERO4 Session cameras at Amazon for less than $100. I have one in my bag as a backup. It fits my existing GoPro mounts, and it has Superview, but I’m always disappointed in the footage I bring home when I have to use it. I’m sure I’ll be saying the same thing about my HERO5 Session when I finally have to upgrade!

I could stick that $100 HERO4 Session and a $15 TPU mount on top of my $130 BFight 210 5” quad. I’m certain that that combination will fly smoother and record better freestyle video than the Caddx Turtle on a 3” micro, and the cost is about the same!

Cost isn’t the only difference

My own 5” miniquad with a GoPro Session weighs 680 grams, and it is capable of traveling at speeds of more than 100 MPH. This has a tremendous impact on safety, and the extra weight means things are more likely to break in a crash.

It is easy to destroy a $300 GoPro in a crash. I broke my first GoPro Session when I crashed into a tree. Trees are solid, but they’re not as solid as concrete! Just like everyone else, I have insurance on my GoPro cameras, so I had that one replaced. That takes time and effort, though.

I don’t just break GoPros, though. I break arms, motors, FPV cameras, and batteries. The heavier your quad, the more likely you are to break something. You might break something on the quad, but you may even break something else.

My 5” miniquad is going to do some serious damage if I hit a window, a car, or a person. A 680-gram object is going to do a lot more damage than a 250-gram object.

This is where we drift back into talking about cost. The motors and batteries on my 5” quad cost about twice as much as the motors and batteries on my 3” Kestrel. This is partly my own choice. My 5” quad uses premium components, while my own Kestrel build is meant to be an inexpensive HD freestyle build!

Risk affects your confidence

I’m usually nervous the first time I try something new or different. I remember the first time I flew over trees instead of in an open field, the first time I flew under trees, and the first time I flew over concrete or water. I was definitely a little shaky!

Over the summer, I was riding my bike past a creek at the park. It is rather narrow, and the water is ten feet below the spot where I could stand. I decided I wanted to fly down there, so I loaded up my cheaper GoPro HERO4 Session, strapped my goggles on, and got into the air.

It was tight down there, and I had to fly slowly. There was quite a bit of scraggle, and I did nearly clip a ghost branch on my way back. I was shaky and nervous the entire time! I was only saving $100 by swapping GoPros. If I wound up in the drink, I could have been out over $600.

I wish I had my Kestrel that day. Risking a total of $230 would have improved my confidence tremendously!

Losing $230 into a river would bum me out very much, but I can do that three times, and it would still be cheaper than losing a single 5” miniquad!

This makes my 3” Kestrel my “hold my beer” quad. Is there a good chance the quad is going to get wet? Am I likely to lose my quad in the woods? Is it going to get stuck on top of a building? Hold my beer, and I’ll use my Kestrel!

Light weight has other advantages!

My usual backpack is a huge ThinkTank FPV Airport Helipak. Loaded up with all my gear and batteries, it is well over 25 pounds. It isn’t bad when I’m driving, but it is quite a bit to carry when I ride my e-bike to the park.

I have an AmazonBasics camera bag that I sometimes use to carry my gear, but I have to pare down quite a bit. I only bring my transmitter, goggles, one quad, and as many batteries as I can squeeze in. Sometimes I strap my 2-pound Moon Lence chair on there as well.

My AmazonBasics DSLR Bag as a Quad Bag

If I take my 5” quad, that means I’ll bring six batteries. With the chair, this weighs just over 12 pounds, and that’s enough batteries to keep me in the air for 18 to 24 minutes.

If I take my 3” Kestrel, I carry six 650 mAh 4S and six 450 mAh 4S packs, and I have plenty of room for more. With the chair, this comes in at around 9 pounds. That’s not a huge difference, but now I’m carrying enough battery for 45 minutes of aggressive freestyle flying, and everything weighs in at about 1/3 as much as my big ThinkTank setup!

I could easily fit more batteries and a spare Kestrel, and it still wouldn’t reach ten pounds. Fitting a second 5” quad would be cumbersome.

It isn’t just the HD video that’s worse than a GoPro

If you run a Turtle or Split, you may also be degrading the quality of your FPV video feed. I use Runcam Micro Eagle cameras on all my 5” miniquads, and the Turtle is a huge downgrade.

The Eagle has a wider field of view, transitions between lighting changes more quickly, and has much better dynamic range. The Runcam Micro Eagle costs $45. That’s 70% of the cost of a Caddx Turtle, but the Turtle also doubles as your HD camera.

I was flying on a cloudy day with the Turtle, and it was nearly impossible to even see the trees without leaves. It is difficult to spot the branches with a Runcam Eagle, but with the Turtle, small trees manage to completely sneak up on me!

FPV is full of trade-offs. This is just another one of those trade offs that you need to be aware of.

I hope the Turtle and Split continue to improve!

I doubt this is the end of the road for the Turtle and Split. They’re outclassed by a $100 GoPro Session from 2014, and that GoPro Session is already quite far behind the current $380 GoPro HERO7 Black. I am confident that Runcam and Caddx will continue to improve these cameras.

I’ll be surprised if a Turtle or Split doesn’t manage to surpass the performance of the old GoPro Session in a couple years. I’m sure GoPro will continue to improve their cameras, so I would be very surprised if Caddx or Runcam could ever manage to actually catch up.

They don’t need to catch up, though. They each have a camera that is a reasonable compromise. Their cameras are a fraction of the price, weigh next to nothing, and do the jobs of both your HD and FPV cameras.

These cameras don’t need to perform as well as a GoPro. They just need to perform well enough, and they almost do that today.

Was the Caddx Turtle the right choice?

I have a short list of reasons for both why I’m pleased and disappointed with the Caddx Turtle. I expect there’s a good chance that I’ll change my mind about some of my complaints, so I’m going to hold off on talking about the pros and cons of the Turtle for now.

It is absolutely fine for what it is: a $65 camera that manages to handle the responsibilities of my $45 Runcam Eagle and my $200 GoPro. It does neither job as well, but it is a great value and compromise at this price point.


Just a year ago, I couldn’t have been more displeased with Splits or Turtles on micro quads. The footage was usually shaky, the quads didn’t fly all that well, and fitting all that gear into a single 20x20 stack was just too much work!

These cameras have made some incremental improvements in their recording capabilities, the 20x20 hardware has improved enough that it almost matches our 30x30 hardware, and Betaflight has micro quads flying better than ever. There’s also no shortage from frames with room for two or three 20x20 stacks—including my own 3” Kestrel frame!

There’s not much excuse left for not carrying a 3” HD micro quad in your FPV backpack. Are you flying with a Turtle or Split? Is it on a micro or a miniquad? What do you think of it? Let me know in the comments below, or stop by our Discord server to chat about it!

Attempting to Make a Calcium-Free Latte

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Over the summer, I was diagnosed with Chronic Kidney Disease (CKD). I could dedicate a series of long blog posts to this topic, but only a small part of my troubles are relevant to this particular blog post. At the time, I may have been just a few weeks or months away from needing dialysis. One of the oddities in my blood tests was a high calcium reading.

I don’t want you to worry. I’ve made changes to my diet, I spent a lot of time sleeping, and my kidneys have adequately resumed their duties, but the high calcium level is still there—though it isn’t all that far outside the normal range now!

My Calcium Free Latte

When my kidney specialist told me to avoid calcium, I didn’t think that would be a problem. I was surprised how difficult it was! At that time, I was sleeping sixteen hours each day, and when I was awake, I was always tired. I’d find myself wandering around the house while my wife was asleep or at work, and I’d be wondering what I should eat.

I didn’t have much of an appetite, but I was often foraging through the cabinets looking for something small and easy to prepare. My choices were limited. When my doctor confirmed that I was diabetic, the diet was quite simple; avoid carbs and eat protein!

He called me the next morning, because the results of my blood test were in, and my kidneys were barely functioning. The kidney specialist threw a wrench into the works. Since my kidneys were failing, I also needed to avoid protein. Avoid carbs. Avoid protein. Avoid calcium.

I was excited one day when I found a can of corn in the cupboard. Butter doesn’t have much calcium, and the carbs aren’t too terrible, and I can microwave corn!

Then I read the nutrition information. That little can of corn had more calcium than a glass of milk or a slice of pizza! I had to give up pizza, and I had to give up my daily lattes. That stupid can of corn wasn’t going to be on my list of high-calcium foods to cheat with!

Giving up lattes

I still remember the day I put the moth balls in my Rancilio Silvia. I was too tired to put the espresso machine away on the day we got home from the news that I can’t have any calcium. A few days later, though, I emptied the reservoir and drained as much water as I could out of the boiler.

It was just another thing I couldn’t have or do anymore. I’d been using that machine every day for nearly four years. Draining Miss Silvia and putting my Craft Coffee subscription on hold was a bummer of epic proportions!

When I started feeling better, I wanted coffee!

When I was asleep more than I was awake, I didn’t really miss drinking lattes. As my condition started to improve, I really wanted to add coffee back to my diet. I’ve been keeping my calorie intake low, and I’ve been avoiding as much sugar and calcium as I can.

I started doing some research. How can I make a latte with no calcium? Avoiding fat and sugar is easy—skim milk and Stevia will do that trick there! How do you avoid calcium?

The Internet gave me all sorts of ideas. Several non-dairy milks are low in calcium. The options available at the grocery store were a different story. I checked the labels on cocounut, almond, and soy milk—any milk-like substance I could get my hands on. They all had as much or more calcium than real milk! I assume they’re fortified in some way.

Non-dairy creamer

I didn’t even look at the non-dairy creamers at first. It seemed blasphemous to use some sort of weird mixture of chemicals and vegetable oil in a latte. I don’t know why I thought this, because I would have considered using soy or almond milk just as blasphemous a year ago!

Non-dairy creamer is calcium free, and it is available with or without sugar. I’m talking about the liquid stuff in the dairy refrigeration, and not that weird powdered stuff. I’m using Nestle Coffee Mate. It is available is all sorts of flavors, but I’m using the original unflavored kind.

Can you make an awesome latte with non-dairy creamer?!

Absolutely not. I experimented a lot, and I still haven’t made anything as good as a latte with 100% whole milk. I’ve made things that aren’t entirely unlike a latte, though, and they taste alright. Not as good as the real thing, but they’re enjoyable.

Coffee Mate creamer lattes taste alright, but the texture is all wrong. They aren’t unpleasant, but the foam isn’t right, and the foam disappears long before you finish sipping your latte.

Heavy cream is low in calcium!

Heavy cream was my first mistake. I don’t know why, but I assumed the fats from the milk were what my latte was missing in regards to both flavor and the problems with the foam.

I was wrong. The heavy cream available at the supermarket is ultra-pasteurized. That means they take it up to a higher temperature than regular milk during the pasteurization process, and this changes the sugars. That changes the flavor a lot. Ultra-pasteurized lattes taste funny.

And the heavy cream didn’t help my foam. It isn’t the fats in the milk that make up the structure of the foam. You need the proteins. You would think I would have figured this out on my own. I’ve steamed skim milk before. The texture isn’t as nice as whole milk, but the foam is plenty stable.

I tried various ratios of non-dairy creamer, heavy cream, and water. The water was to bulk up the contents of the steaming pitcher a bit. It also helped dilute the latte without adding additional fat or calories. I don’t add water to my pitcher anymore, but it did work well enough.

The important lesson that I learned here is that milk is quite different than watered-down heavy cream!

If you want proper foam, you need to add some milk!

I’ve given up on making completely calcium-free lattes. My levels are down quite a bit, and they may even be in the normal range next time I get checked. I’ve been adding some milk to my steaming pitcher.

It doesn’t take a lot of milk to improve the foam by a huge margin. I’ve tried ratios of around 20% milk and 80% heavy cream, and even that comes out looking and feeling so much more like a proper latte than a 100% Coffee Mate latte.

The more milk you use, the better it tastes. I’ve settled in on using about 1/3 2% milk with 2/3 Coffee Mate non-dairy creamer. It isn’t perfect, but it is definitely satisfying my craving.

I’m not certain how much of each ingredient I’m actually ingesting. There’s always a lot of extra liquid left in the pitcher. I imagine that most of the foam winds up coming from the milk, while the remainder of the steamed liquid is close to the expected ratio of milk and creamer.

I’ve switched from my old triple-shot basket to a double-shot, so I’ve reduced the size of my overall latte by 1/3. One 8-ounce serving of milk has roughly 300 mg of calcium.

I’m probably putting about 3 ounces of milk into my steaming pitcher, so that’s a total of 100 mg of calcium. I’m using about half of the volume of fluid from the pitcher in my double-shot latte. I imagine I’m getting somewhere around 50 mg of calcium per latte—certainly less than 100 mg!

Stevia instead of sugar?!

I am definitely leaning towards the diabetic side. It is at the very least a major contributing factor in my kidneys shutting down. I’ve been doing a good job managing my carbohydrates, and my glucose numbers are still a little above normal, so I’m avoiding using sugar in my lattes.

I’ve tried Stevia and Splenda. Neither tastes right, but I’ve learned that if I use both Stevia and sugar, I barely notice the odd taste of the Stevia.

Sugar in a latte?! That’s crazy talk!

Quite a few years ago, I learned that I am a supertaster. I guess most supertasters learn to tolerate the strong flavors that they don’t enjoy, and it seems to be common for those supertasters to find their calling as chefs.

I never learned this skill. I’ve tried tasting regular coffee and espresso right out of the machine. My photography and limited audio-editing expertise would describe the sensation as being a lot like clipping. No matter the coffee, my bitter taste buds feel like they’re maxed out.

Add some milk and sugar, and I can usually pick out many of the things that Craft Coffee lists on their tasting notes on each bag of beans.

I will be sticking with sweet lattes.

Whole milk is so much better

I do cheat every once in a while. After taking such a long vacation from the Rancilio Silvia, my success ratio with pulling shots has plummeted. I’m doing better, but I’m still much more likely to get a fast pull than I used to be.

When I see what seems to be a perfectly timed pull, I think about dumping out my concoction of Coffee Mate creamer, milk, and heavy cream. Will one whole-milk latte kill me? I’d say I’ve cheated roughly once a month, and I try to use 100% whole milk and all sugar at least once with each bag of coffee beans.

The foam is better. The texture of the milk is better. Milk tastes better. Drinking a 100% whole-milk latte is an amazing treat for me!


I was hoping that last month’s blood test would tell me that my calcium levels were fine. I already knew my kidneys were doing a fantastic job again, and there was a good chance my worries about high calcium levels were over. I wasn’t quite that lucky, but that’s OK!

I’m functioning well enough that I can get away with eating a couple slices of pizza and drinking one whole-milk latte every month, but I think I’m going to be drinking these downgraded lattes for a long time. I better get used to them!

I don’t think this post will have a wide audience. My Google searches for a calcium-free latte came up completely empty. I imagine there aren’t a lot of folks making lattes at home every day, and a low-calcium diet seems extremely uncommon. I doubt there’s much overlap between those two groups!

I bet there are at least two of us, though! I’ve already done the research and experimentation. Now you don’t have to!

Cutting Carbon Fiber Sheets on My Shapeoko CNC

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The list of materials you can cut with a CNC router seems endless. Wood is very common, and it looks like my Shapeoko XXL can even manage to handle aluminum. I didn’t buy a CNC machine to cut either of those materials. I’m sure I’ll find some excused to do some woodworking projects in the future, but I bought my machine to cut carbon fiber quadcopter frames!

Shapeoko XXL Cutting Carbon Fiber

If your CNC machine can handle hardwood or aluminum, you shouldn’t have any trouble cutting carbon fiber sheets. You certainly don’t need a machine as big or as powerful as the Shapeoko or an X-Carve.

Safety first!

Carbon fiber dust is hazardous. It is conductive, and it gets all over everything. The dust might manage to short circuit something in your laptop. It will get into your router. It will get in your lungs.

That last part is the scary part. Take lots of precautions. Wear a mask. Keep the garage door open, and point a big fan over your machine and out the door. Better yet, pick up the machine and take it out into the driveway!

Me and My Dust Mask

I wear a mask, and I’m constantly running my little Shopvac knockoff. I would give you a link to the mask I’m using, but I doubt it is really up to snuff. It has a filter, and it doesn’t leave any gaps around my nose. To be properly safe, I should probably look like Barbeque from G.I. Joe.

If I end up doing this often enough, I plan to build an enclosure for my Shapeoko. I’ll put a blower on that enclosure, and I’ll plumb it up to a dryer vent. I haven’t gotten that far along, though.

Be safe. Do your best. Do a better job than I am!

Tell me about these carbon fiber sheets!

I’m not an expert, but as far as I know, there are two common ways to work with carbon fiber. You can shape the woven fabric, then coat it with epoxy. This is a lot like repairing a fiberglass hot tub.

Quadcopter frames are cut from premade sheets of carbon fiber. The factory stacks layers of carbon fiber, and they impregnate it with epoxy resin. The process generates flat sheets. The sheets I’m using have alternating layers with the carbon fibers rotated 90 degrees. The top and bottom layers have the woven pattern.

The sheets I’m using today are 1 mm, 2 mm, or 3 mm thick.

This stuff is really sturdy! Is it hard to cut?

Carbon fiber is actually quite easy to cut. Your router doesn’t need a ton of torque or speed—my router’s minimum speed is actually too fast!

My feeds and speeds

This is probably the tl;dr section of this post. How do I cut carbon fiber sheets?

I’m using 1/16” fishtail endmills that I bought on eBay. They’re about $20 for a pack of 10. I haven’t broken one yet, but I will be sure to keep pushing my feeds higher until I do!

1/16-inch Endmills from eBay

These are my current settings:

  • Depth per pass: 0.8 mm
  • Feed rate: 320 mm/minute
  • Plunge rate: 100 mm/minute
  • Router speed: 1 on the Dewalt DWP611

I’ve tested all sorts of settings. I’ve gone as high as 800 mm/minute with a cut depth of 0.5 mm. I broke a $20 bit from Carbide 3D on that cut. I’m not sure the speed was the problem, though. My 3 mm carbon fiber sheet came loose during that cut, and I assume that put a lot of stress on the bit.

The math says I should be running my router at 5,000 to 6,000 RPM. My Dewalt router can’t run that slowly. I believe the lowest setting works out to around 20,000 RPM. Too much speed generates heat, and it cuts out dust instead of chips. The heat could be bad for the epoxy, but it hasn’t been problematic yet!

I chose a depth per pass of 0.8 mm, because I’m cutting 3.2 mm deep on my 3 mm sheets of carbon. That means I can cut all the way through a single sheet of carbon in four passes. Choosing your depth per pass based on the thickness of your material seems smart!

My parts are coming out clean and smooth, and I don’t need to do any cleanup afterwards.

I can reduce my number of passes to three if I increase the depth per pass to 1.1 mm. I plan to test this, and I will also be increasing my feed rate.

How much cutting have you done so far?

I am not an expert. I have cut about three quadcopter frames’ worth of parts. Not three complete frames, though. My design process is iterative, so I’ve been replacing parts as I make improvements.

I’ve used up almost half of my first 400x500x3 mm sheet of carbon fiber, and I’ve ordered a less-expensive second sheet from another vendor!

3-inch Kestrel HD Micro Quad

The 400x500 mm 3K carbon fiber sheets are definitely high quality. I ordered those from I ordered another sheet of 3 mm 3K carbon fiber from Hobby King. That sheet hasn’t arrived yet, and they don’t stock 400x500 mm sheets. Their prices are quite a bit better, though. You get about 40% more material for your dollar at Hobby King.

I’ll have to crash the new, cheaper sheet to see how sturdy it is!


I don’t know why, but I thought this would be a longer blog! I guess there’s not much to say. These are my feed rates. These are the bits I’m using. This is the carbon fiber I’m cutting. The cuts are clean. Done. Right?

I plan to push my feed rates and depths as high as I can. That’s just what I do. I pushed my 3D printer as fast as it could go. I push my quadcopters as fast as they can go. So why not push my Shapeoko as fast as it can go, too?!

Are you cutting carbon fiber on your CNC router? Are you having as much success as I am? I’d love to hear about your machine and your process! Leave a comment a below, or stop by [our Discord server][bw] and chat with me about it!

The Kestrel FPV HD Micro Drone: The Road to the Second Prototype

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Almost everything regarding my new frame design has been working out better than I expected. Using the Shapeoko XXL is easy. Cutting carbon fiber was even easier than I expected. The first prototype fit together quite well, and it flew almost perfectly. I mostly just needed to tune the PIDs on the pitch axis, because of that long fuselage on the Kestrel.

I’m slightly exaggerating. The first test cuts of the earliest prototype didn’t go perfectly. The bottom and side plates came out great, but the arms broke free of the carbon fiber before the motor holes were drilled. It wasn’t a big deal, and I learned from my mistakes. It also gave me a chance to test fit all the parts of the fuselage before cutting again.

The Kestrel FPV Micro HD Frame

That first fuselage was beefy. Much too beefy. The side plates are cut out of 3 mm carbon fiber sheets, and I believe I made the length of the side plates 6 or 7 mm thick. It didn’t need to be that sturdy. I’ve dialed that back quite a bit.

All my holes for M2 and M3 screws were too tight, and the slots in the side plates for mounting the top plate were too snug. I managed to get that first fuselage assembled, but I had to widen all the M3 holes, and I had to tap the top plate into place with a hammer!

I was excited to see that my design was coming together, though. All I had to do was tweak three or four variables, run the SVG files through my CAM software, and cut the real prototype!

The prototype flies great, but…

One of my major goals for this project is to build a lighter Acrobrat. Using those beefy 7 mm rails and having a beefy camera pod on the side plates may look nice and sturdy, but it adds quite a few grams.

I only know one way to figure out just how light, thin, and spindly you can make your quadcopter frame. That’s to make it thinner than you think you can get away with, then crash the heck out of it! Wherever it breaks is too thin, so that’s where it needs to be reinforced!

NOTE: Test flight before the Caddx Turtle V2 arrived. I wasn’t smart enough to update the name in the OSD!

There are a few spots I’m still worried about. The tabs that slot into the vibration-dampening bushings of the side plates can only be so wide, and the bottom plate is only 2 mm thick. I’m expecting that to be the weak point in a crash, but I’m also worried that I’ll need to make those tabs even narrower to allow the bushings to float a little more freely. We’ll see how that goes.

If it is a freestyle frame, how light can it get?

I’m concerned about this. The Acrobrat is designed to use 1407 or 1408 motors, and everything that goes along with that can easily push your weight over 250 grams. I’m not personally worried about the 250-gram limit, but doesn’t it seem like an interesting target to design against?

Heavier quads are better for freestyle. My prototype Kestrel frame is using all the hardware from my Leader 3, including the tiny 1106 motors. A whole set of those 1106 motors weighs less than a pair of 1408 motors, by the way.

I’ve flown my Leader 3 quite a bit, and upgrading to the Kestrel frame and a Caddx Turtle hasn’t increased the weight all that much. Even with the new camera and heavier frame, I believe I’m still lighter than my friend Brian’s Diatone GT-M3!

Flying freestyle with a quad that weighs 160 grams with a battery is challenging. My 680 gram 5” quad is an entirely different beast. I can huck him over a tree, roll upside down before I even reach the tree, and then finish off the S-turn when I get past.

The Kestrel FPV Micro HD Frame

With the 160-gram Leader 3, I can’t do that. If I invert before I clear the tree, my quad will likely end up in the tree. I have to wait until I’m almost past the tree before inverting with the Leader 3 or my 1106 Kestrel.

My Kestrel build weighs in at about 185 grams with a 4S 450 mAh battery. It flies for 2.5 to 4 minutes on a charge, but most of the time I land at just barely over 3 minutes. I tend to get pretty close to 3.3 volts per cell, but they usually recover to 3.7 volts shortly after the flight.

I ordered a bunch of 4S 650 mAh packs, too. They should put my Kestrel at just over 200 grams. I think it will be interesting to see if the extra weight makes the quad a little more huckable, and I’d like to see how that influences my flight times.

UPDATE: On my current prototype frame, my 1106 Kestrel weighs 128 grams dry, 189 grams with a 450 mAh 4S, and 217 grams with a 650 mAh 4S.

My friend Brian transplanted his Diatone GT-M3 with HGLRC 1407 motors over to a Kestrel frame, and he added a Caddx Turtle. The Diatone frame must be heavy, because the weight is one gram lighter after the upgrade! His Kestrel with 1407 motors weighs 168 grams dry, and 253 grams with a 650 mAh 4S battery.

If weight helps with freestyle, why keep the weight down?

In the end, it all comes down to cost. If I want to upgrade from 1106 to 1408 motors, I’m going to be carrying quite a bit more weight. That means my arms need to be sturdier, and that adds more weight. This extra weight starts to add up, and now I might need to upgrade to a bigger battery.

At this point, maybe the camera protection needs to get beefier, too. The bigger motors on the heavier quad will also be rougher on your batteries, and you’ll be more like to damage someone’s property when you crash.

Heavier quads are more likely to break, and they’re more likely to damage property. I can always make the frame tougher. That just adds more weight, and it doesn’t keep the other exposed components safe. A 180-gram quad is less likely to break a camera or battery than a 250-gram quad!

My perspective might also be a little different. In some parts of the world, that 250-gram weight limit is a real limitation. In those places, your only choice for freestyle might be a 250 gram drone!

The Kestrel FPV Micro HD Frame

For me, my HD micro drone is more of a backup; almost an afterthought. It is an extra piece of gear to keep in my bag alongside my 5” and 6” quads for those times when a bigger quad isn’t appropriate.

As I’m writing this, I realize that this sounds like a strange perspective for someone to have when they’re putting all this time and effort into designing a 3” HD micro quadcopter frame!

I know I’m not the only person interested in this sort of frame. I want something light, inexpensive, and relatively safe to keep in my bag. Adding an HD camera is a huge bonus for me. I’m sure I’ll miss my GoPro and superview when I fly my Kestrel, but I absolutely expect to fly my Kestrel in situations where I wouldn’t dare fly my 5” quad!

Of course, the Kestrel won’t just be for 1106 quads. I’m going to be making wider arms for 1408 motors, and I’m also going to try longer arms for 1806 or even 2204 motors with 4” props. My prototype will be for my specific use case.

Rubber bushings don’t solve all problems!

My first day out flying with an HD camera on the prototype Kestrel was a disappointment. I had a flutter at full throttle, and my cruising footage wasn’t smooth at all—even with a fresh set of props!

When I got home, I noticed that my flight stack wasn’t secure. I was surprised, because I wiggled it around to make sure it was solid while I was installing the Caddx Turtle. Two standoffs between the flight controller and ESC were busted, and two standoffs between the frame and ESC were broken as well!

I took out all the old nylon standoffs and soft-mount standoffs, and I replaced them with fresh M2 nylon standoffs. It is too bad I couldn’t reuse the soft standoffs. A piece of a nylon standoff broke off inside, so I just replaced them all with regular standoffs.

NOTE: Sorry about the vibrating footage!

It was almost dark when I finished buttoning the Kestrel back up, so I just took it outside the house to give it a few punches. My full-throttle oscillation seems to be gone. I didn’t get to do much slow cruising, but I’m hopeful that the shakiness is gone there, too.

You also need clean props. I tried to make a pass under my car, and I forgot to flip the switch from air mode to rate mode, and I chewed up the tips of two props on the pavement. They didn’t look terrible, but that definitely added more vibration.

I’m hopeful that the rubber bushings will help silence some vibrations, but I know for sure that it will only reduce vibrations with low amplitudes. I think I’ll be changing props a lot more often with an HD camera!

You sure do talk a lot, Pat. You haven’t even told us what’s next!

Yeah. I’m doing a bad job of getting to the point of this blog post!

I’m quite pleased with the first prototype of the Kestrel. I will probably be flying my copy as it is for quite a while, but I plan to cut frames for some friends soon. The prototype isn’t without flaws, but I am thankful that they’re not show-stoppers!

The Kestrel FPV Micro HD Frame

The most obvious problem is the camera protection. I based the radius of the curve on Caddx’s measurements for the Turtle. I’m guessing that those measurements don’t apply to the bigger lens on the newer Turtle cameras, because the lens sticks out nearly 2 mm past the front end of my quad!

That was easy enough to fix. I just had to adjust a variable. That’s why I love OpenSCAD.

I left the bottom standoff out of the build, but the holes are still there in the prototype. It turns out that I don’t need it for rigidity, and leaving it out saved more than 2 grams. I don’t know that I could put it back in place, either, because it would be awfully close to the camera.

It will just barely fit, and I’ll probably put it back in place before my test flights. The wiring harness for the Caddx Turtle is at the bottom, and on my current build, those wires will be exposed in a crash, and they are fragile wires.

I’ve already adjusted the model in an attempt to alleviate this issue. There’s plenty of room to bring the camera backwards. I moved the camera upwards by a few mm, and back far enough that the camera’s mounting screw is behind the center of the front bushing.

That should be back far enough that the frame’s bottom plate will protect the camera. In the worst case, I can extend the bottom plate forward far enough to keep those wires safe.

I also rearranged the various support pieces near the camera. I eliminated the vertical post connecting the front bushing to the front standoff. The camera is close enough, so I’m hopeful that the camera pod will be structurally sound enough to support the entirety of the front end. I also adjusted one of the camera’s braces so that it follows the direction of the carbon for strength.

The Kestrel FPV Micro HD Frame

Moving the camera back left the standoff a little too close to the camera. I’ve pushed that standoff back, so it shouldn’t interfere with uptilt.

While I was working with the side plate, I also decided to drop the deck by 3 mm. It should still be quite roomy. My stack is still using a set of tall standoffs to cap off the top, and those are a bit tall. I’ll probably still have just enough room even with those giant standoffs being used as screws, but I’ll just swap them out for proper M2 nylon nuts.

I’ve moved the camera back quite far. I think I’ll be OK, but there is a possibility that the props will be in view with the new design. If they are, I will adjust the angle of the arms to compensate!

The Foxeer Mix camera

I was waiting for my Caddx Turtle to arrive before I started messing with the shape and location of the camera pod. I wanted to move the camera inward, but not so far that I might interfere with the Turtle’s circuit board. I wanted to see it in the real world. I didn’t quite trust my measurements!

It turns out I have plenty of room for the Turtle, so I moved the camera way back. I looked up the Foxeer Mix HD camera, and I couldn’t believe how big its circuit board is! It is 37 mm long and wide!

I’m not even going to attempt to accommodate it in my frame. At 37 mm, it will stick quite far out each side of my frame. Not only that, but I wouldn’t be able to push the camera back very far at all.

It is a good thing the Foxeer Mix didn’t wind up being the most amazing HD FPV camera, or I might be disappointed!

I’m going to need testers!

Designing the Kestrel has been a lot of fun. Almost as much fun as flying it! Weather, camera problems, and my own mistakes have greatly impacted my flight time, and I’m realizing that I don’t need to be doing all the test flying on my own!

I’m looking for help. I don’t have enough time, parts, or funding to test every configuration that I’d like to support with the Kestrel. I’m most interested in the 1106-scale version of the frame, so that is where I’m focusing my time.

I’m about to cut a frame for my friend Brian. He’s going to be transplanting his upgraded Diatone GT-M3, so I’ll be cutting him beefier arms with wider holes to support both 9 mm or 12 mm motor hole spacing. I expect he’ll be right at or just over the 250 gram limit. I’m excited about taking his heavier Kestrel for a spin!

I’m also extremely interested in seeing a Kestrel with 4” arms, especially if it squeezes in under 250 grams! I don’t expect to be building one of these any time soon. I think it’d be a very interesting build, but at this point, it’d be too much like my 5” quads for me to include it in my fleet.

So what do you want to build?

I want to hear about what you want to build. If you’re an experienced freestyle pilot, and you want a Kestrel frame customized for an interesting configuration, please contact me! Leave a comment, send me an email, or stop by our Discord server. I have no idea what kind of a response I’m going to get from my request for help, so I have no idea how this is going to go.

I expect I’ll be sending a freebie prototype to a few select pilots, but I’d like to get as many of these out into the world as I can manage. Even so, I’m limited by my production capacity.

I’m going to have to figure out a reasonable way to charge for my time and materials if enough people are actually interested in trying out my frame.

How much will a prototype frame cost?

I tend to be overly honest and forthcoming about my costs and processes. This is probably why I’m a terrible business-person.

I did some very naive math after my first successful cut of a frame. I measured about how much space I used on each sheet of carbon, then figured out approximately how many frames I could fit on each sheet. I’m using relatively expensive carbon fiber sheets from GetFPV.

My math says each frame consumes just shy of $14 worth of carbon fiber. I can probably cut that in half if I use cheaper carbon, but I’m quite pleased with how sturdy it is. The cheap 3mm carbon from the Leader 3 is much easier to flex!

Lazy 3-day shipping withing the United States is around $7. Lets just say it costs me $20 of actual cash out of my pocket to get a frame out the door.

I haven’t taken labor into account. Sure, the CNC machine does most of the work, but at this point, I have to babysit for an hour or more for each frame. So far, I’ve broken a $20 endmill while cutting frames. I don’t know how often I’ll be breaking stuff, but I’ll need to account for that.

Things will slowly get more efficient on my end. If I ever get to the point where I can mass-produce these, I’m certain my costs will go down, too!

But this is where we’re at today. I have to make them myself. If you have interesting plans for my frame, please let me know!

How can I help support Pat?

I’ve set up an account on Patreon. I haven’t thought this through as well as I’d like, but here’s what I’m imagining so far. If you like what I’m doing, and you’d like to make sure I have access to the supplies and tools I need to keep doing these things, you can support me at Patreon.

I would prefer to provide a product or a more tangible service. Buying my frame would be a great way to support my future development, but I’m really not there yet. I’m going to be a huge production bottleneck for the time being.

There are Amazon and eBay affiliate links all over the place on my blog. You don’t have to buy what I’m linking to. Any purchase made shortly after clicking one of my links will earn me a small percentage, and every little bit helps!

This section could use a blog post or Patreon post of its own—maybe both! I need to put more thought into this.

The current specs of Pat’s personal Kestrel prototype

My Kestrel is built using the guts of a Full Speed Leader 3 and a Caddx Turtle. It is currently weighing in at 123 grams dry, and 183 grams with a 4S 450 mAh CNHL battery. I’m getting flight times ranging from 2.5 minutes to 4.5 minutes, but most of my somewhat aggressive freestyle flights come in at right around 3 minutes.

Here’s the laundry list:

  • F4 Flight Controller
  • 28 amp blheli_s 4-in-1 ESC
  • 25-600 mw VTX (my smartaudio is busted!)
  • 1106 4500 kv motors
  • Caddx Turtle V2
  • HQ 3x3x3 3-hole props
  • Crappy dipole antenna
  • 186 grams with CNHL 4S 450 mAh
  • GPL licensed design
  • Currently hosted on Thingiverse


I’ve already started cutting updated carbon. We’ll probably be transplanting Brian’s Diatone GT-M3 this weekend or early next week. I can’t wait to see how that flies.

I’m excited. I’m tweaking designs, cutting frames, and slowly collecting some HD footage. I’m sure it won’t be long before the next update, especially if it stops being rainy and cloudy!

Are you looking for a lighter 3” freestyle frame with removable arms? Do you think I’m on the right track here? Are you interested in helping me test my design? Leave a comment, or stop by our Discord server and talk to me!