This project includes development of the next generation of frames that began as a speed project, but will also give rise to production frames for racing, freestyle, and endurance.

NOTE: Most, if not all, updates are in regards to the speed project.


  1. Progress Updates
  2. Frame Evolution… or Revolution?
  3. Lightweight Frame Test
  4. Modular Design
  5. Electronics



Progress Updates

March 1, 2018: I must remember: hit the record button. I only have video of 4s runs (boring). This is why I will be making a checklist… I flew a few times over the month with no significant flights (due to weather) except for yesterday. It was relatively warm at the time (50°F) so I decided to tune in some APC 5050 props on 5s and do a few short speed runs (only 1.5-2 seconds WOT). The first 5s flight began and ended with some PID adjustments but I got a couple speed passes in between. 146mph/235kph is nothing remarkable, but I’ll take it considering that:

  • The PIDs still needed to be lowered (oscillations at WOT)
  • The time at WOT was only 2 seconds
  • Relatively cool temp, so the batteries were cool
  • Only 2 speed passes which didn’t give the battery a chance to heat up – it was barely warm
  • A “practice” nose cone with higher drag was being used
  • In the past, the 4th or 5th speed passes are the fastest and are typically about 15-20mph/24-32kph faster (since the battery warms up and internal resistance drops)

I wanted to continue and try some 5060 props, but then my motors became afflicted with the “mystery” rocks (more like the size of sand). I ended up getting some dirt/sand in the motors on one of the landings. To put it as short as possible: I blew out the sand, thought all was good, but after about 20 seconds, motor 1 failed. At home, I still felt the sand in the motors and could not blow it out. When taking apart the motors, I found what looked to be like very small rocks sticking to the magnets – sticking since they were magnetic (mildly magnetic). In my metal working experience, I have never seen any metal that has looked like this so they are not any part of the motor. Being magnetic, they wreaked havoc on the motors and scratched up the magnets and one motor had a dislodged magnet while another had 2 dislodged magnets. The impact to the ground was relatively soft, so I don’t think the impact dislodged them. It’s still inconclusive as to what actually happened, but here is a picture of one of the magnetic rocks:

Magnetic rock
Motors do not appreciate tiny magnetic rocks, especially while spinning at 30-40k RPM

January 29, 2018: After a couple of “mishaps”, a few other issues (gyro not wanting to calibrate), and wanting an external sd card for blackbox logging, I decided to go with the Joshua Bardwell Edition F4 Flight Controller which I just ordered from Rotor Riot – they DEFINITELY get 17 out of 10 stars for their customer service! As far as I have heard, the JBF4 reviews are great and it has everything I need. A close runner up was the CL Racing (which uses the same hex as the Bardwell F4) but there are too many “death roll” reports.


Although the weather is looking rough, I did find a large field not too far away that I can do some test runs – this should help a bit with progress.

January 16, 2018: A quick test flight was done last week on 4s. A poor decision in construction made one of the ESC wires break loose and ended up crashing. Temp was 30°F and I didn’t go full throttle long enough to get to top speed. I didn’t want to let it go too far out since the snow was deep and it would make crash recovery tough.

Conformal coating was used and no major damage. The frame will be reworked to the latest revision of the frame, which is the final revision.

I have changed my mind about having the frames adjustable in size. Instead, I will build separate frame sizes. I would rather have each frame ready to go instead of reconfiguring them. Although the idea is simple, I would rather not deal with that right now… So the fleet will be like this:

  • 2 5s “Revision B” frames (for flight tests)
  • 1 6s “Revision B” frame (for flight tests)
  • 3 5s “Revision C” frames
  • 3 6s “Revision C” frames

Yes, 5s is plenty, but 6s will also be used just for an added cusion. No matter how you slice it, the math shows that anything more than 6s will only turn into heat and excessive amp draw.

December 30, 2017: The date has been set and the world record fleet (Guinness World Record attempt for speed) is slowly coming together. Although they are in various stages of completion (only one is flyable at the moment), there is plenty of time to refine the frames. Right now there are 5 frames, but this number might increase slightly. When I say frames, I mean the base structure since being a modular design, they will all share 3 or 4 sets of electronic modules. Goals for the world record day:

  • Have at least 5 base frames
  • Frames can be configured with different arm layouts
  • Frame bodies can be configured for different battery sizes.
  • Although only the top overall speed will go in the books, top speeds will be attempted for different battery cell sizes.
  • Other records (not using my frame) that will be attempted on the same set of days are quadcopter endurance and fastest quadcopter ascent to 100m.

December 29, 2017: A small update – due to independent motor tests and the recent Choosing The Right Motor blog post, I have decided to stick with the Cobra CP2207 2450kv motors.

VX1 05
Cobra motors shown on the VX1 project

December 8, 2017: The Future is Clearer: Not so clear on the site – I will have to expand on this over the next few days (slightly). In short, the speed fleet is being built. They are slightly different from each other and completely interchangeable with one another using a modular design. If a new idea does pop up, it can easily and quickly be integrated. Overall I am extremely happy with just about all aspects of the design, but I am extremely unhappy with the weather. Hmmmm, maybe a heated transmitter powered by a lipo should be next on the project list…

November 28, 2017: The 5″ production prototype (race/freestyle) is a bit heavier than anticipated at 44g, but it should be able to be trimmed to 36-38g. More info is in the video description about the build, but it was done in an extreme rush. Some specs so far:

  • 215mm Motor to motor distance
  • Final design will be around 36-38g
  • The only fasteners will be for the motors and the stack – no fasteners, epoxy, glue, etc. is needed to hold the frame together (although the one in the video used 2)

November 14, 2017: The next prototype frame is well under way. I do not expect much to happen in terms of flying, but if I do get a chance, it won’t be a surprise if it breaks 165.80 mph mark set by the VXR-190. Although I expect this prototype to do very well, there will be more frames being built to hone in on the features that the final build will have.

November 5, 2017: I finally had a flight with the first frame design which is already obsolete, but it still had some other aspects that had to be tested and was successful. I’m not bothering with video since it was beyond boring and I was only flying with a 4s. So now it is on to the next frame. If it goes the way I hope, it is going to be very cool in terms of having a modular design.

By the way, with the updated Blheli 32.1 update, the Wraith32 ESCs sound great.

October 5, 2017: I never quite finished the first prototype (this is common for me), it never quite felt right. The 2nd prototype frame is almost done (no electronics yet). The arm design is radically different from previous designs. Once this design has been proven, it will be on to the more refined version. However, both of these frames (if they work) will not have the goal of all out speed. As stated earlier, the current goal is to get some testing on different configurations – many different configurations that can be accommodated and switched out (relatively easily) on the test frame. Whether it hits 200 mph or 36.2 mph, I will be sure to post videos. Hopefully this will be next week.

September 2, 2017: After looking at this build, I really don’t expect to be finished until spring. Although this sounds like a long time frame, a lot of progress will be made along the way. Why? This design is more of an adaptive design (at least that is what I am aiming for). There will be a core frame which can be modified relatively quickly with different sub assemblies. With that being said, there might be many configurations that will be tried out before the best combination is found.

August 29, 2017: The official start of the next speed project. I don’t have any specific goals or speeds to hit since there are a lot of unknowns. It really kills me, but for good reasons, I will be giving even less details about this build for the time being.

I do plan on posting what I can (numbers, logs, video, etc.) as things progress. I hope to have a frame or two built by this weekend, but as history has shown, it will probably be 2 or 3 weeks until something good happens.


Frame Evolution… or Revolution?

Although flying time has been lacking, there has been plenty of time to develop, evolve, and build different arm configurations using different construction methods and materials. The latest configuration design is extremely promising as far as versatility, strength, low cross section, balance, and has a high possibility for production kits. The design scales down extremely well while retaining its strength.

Another big development is the motor mounting. It might sound odd, but it is a big breakthrough.

So far, these are the frames that have been constructed using this method and their weights. Just in case, a lot of this should still be taken with a grain of salt and all weights given are bare bones:

  • 5″ Speed Drone Frame: 26g (excludes nose and tail cones)
  • 5″ Freestyle/Race Frame: 20.25g. This frame has me very, very excited.
    • I would like to refine this version into a frame that can have replaceable arms. I am guessing it would add another 6-8g.
    • There is a slightly promising method that might only add 2-4g to have the arms replaceable.
  • 5″ Light Weight Frame: 9.96g. Although this frame can support 95 lbs (see picture below) this might need just a little more to strengthen it (torsionally), but It shouldn’t be more than 11g.
  • 5″ Featherweight Frame: 5g or less. This is still in progress and is at 4.45g. I am still pinching myself over this one… but something tells me it wouldn’t hold up to hard flying or maybe just hovering… This one is on the shelf for the moment.


Lightweight Frame Test

A dirty test setup: the frame is placed over a pot. The arms are supported on the rim near the motors. In the middle of the frame is a 1.5 inch square block to set weights on. I ran out of weights, so I threw the bar on too.

I ran out of weights, so I added the bar. It might look like some weight is resting on the pot handle, but all 95 lbs (roughly) is resting on the 5″ 9.96g frame which is hidden under the weights.


Modular Design

Just a quick mention – I can see this frame being developed into a kit that can be configured several different ways by adding components to the bare bones frame.



About the only thing I have confirmed is using a Betaflight F4 flight controller.

Betaflight F4 front

Betaflight F4 back

For the initial ESC choice, I will be going with the Airbot Wraith32 Metal. Since Airbot was nice enough to send these to me, this might be a good chance to redo my Wraith32 review. Apparently, the firmware was at fault on my initial review.

The reason I want to use these ESCs is so I can record and analyze the data from the ESC telemetry.

Wraith32 Metal
Wraith32 35A on the left and Wraith32 Metal 65A on the right

And of course, I will be using the ublox M8N for the GPS reciever.



6 thoughts on “XLR-1

  1. Torashuu says:

    Very nice site, was wondering when someone was actually going to design around frame aerodynamics in a more rigorous way. I’ll be keeping an eye out for any frames you might put out.

    Liked by 1 person

    1. downanddirtydrones says:

      Thanks! Truthfully, the site is a little disorganized. I need to take a day or 2 to clean it up. Aerodynamics on these things are not straightforward – I think there will always be a compromise but I’ll try my best.


  2. Torashuu says:

    Dont worry about site organization, so long as the principal ideas are there (excempting those involved in any patents of course). Just the clarification of the possible gains, the back of the envelope calculation on maximum attainable speed already sets some rough limits and goals that give you something to work with, contrary to regular frame design which seems mostly based on gut feeling and user feedback. Not to mention this actually gets me thinking about custom frame design for myself. 🙂

    Liked by 1 person

    1. downanddirtydrones says:

      Glad to hear – back of the envelope is about all you can do with these things. It was a good sign that I was doing something right when a small group of guys took me in back in July – very smart guys. A few affiliated with R & D in various aerospace and air defense industries, dozens of patents among them, all retired early – hopefully by their choice 😉 We have a rather lengthy confidentiality agreement among us and we bounce ideas, verify, etc. Since being in the group, I haven’t had to change the Speed Calculation spreadsheet at all. That’s not to say it couldn’t be improved! Although the website is in the doldrums (as far as info goes), things are busy behind the scenes – very tough to stay focused… I almost forgot to mention: frame design is addicting. I started by modifying existing kits. Some are so cheap, you can buy a few kits and use them for materials.


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