Mini Tricopter thoughts – need feedback


I’ve been working on the Mini Tricopter for quite some time now and to be honest the design has been more or less done for almost a month. However I haven’t released it on the store for a couple of reasons that I would like to discuss with you, and hopefully get some input on how I should proceed.

The design

Designing a Mini Tricopter really is like stuffing 10 people into a VW golf; It’s going to be pretty cramped. The tail rotor limits how far back you can fit things, where as on a Quad you can stretch out the gear forward and backwards without hitting anything. However, putting all the gear tightly together means that the center of mass is is very close to the center of gravity, which means good and equal handling in both axis.

I’m fairly happy with the design overall. It’s cramped, but it does work well. It uses the same Naze and PDB as the original tricopter. It also uses the same servo, tilt mechanism, motor mounts, front spacer and arms (cut to half length). Which means that anyone with a regular size tricopter easily can convert theirs to a Mini Tricopter simply by cutting the arms and screwing on the Mini Tricopter add-on frame. (Be careful if you do decide to cut carbon fiber though, it is damaging to the lungs/eyes and so on!)


The frame has a built in adjustable mount for a board-camera with up to a 40x40mm footprint. The angle can be adjusted continuously between 0 and 40° so that you can start out easy and as you progress in your flying, you can add more and more angle to the camera. The camera is also well protected by the frame itself and the fact that it is held in place by rubber bands, which protects the camera even more during a crash.


The Mini Tricpter easily carries a GoPro. Unfortunately I couldn’t make the GoPro protected inside of the frame without compromising the design. The GoPro 4 sessions does fit inside of the frame, as does a Mobius camera. The Original Gopro sits on top of the frame using the original GoPro mount and housing.

The recommended setup would be:

  • 4S 1800mAh 45C LiPo
  • DYS-2208 1800kV
  • DYS-SN20A BL-Heli ESC’s
  • HQ6x4.5 props


The setup is great. It draws 60A on full throttle (20A per motor) and top speed is almost 100mph/160km/h (with some tail wind).

Flight time is decent at around 5 minutes and it does take a crash well. The arms fold up absorbing energy and the tail stands up to the punishment much better than expected.

Overall I’m very happy with the design. Still, there are a few things weighing on my mind…

The flight characteristics

This thing is faaaast. The thin arms and smallish body makes it rather aerodynamic slippery. It requires very little power to cruise at a pretty respectable pace, and herein lays one of the problems. I originally designed this Mini Tricopter to be a racer, and sure it can race. But not on small courses. The problem is that it’s simply too fast once you tilt it forward and start racing. I discovered this during the AGP race in Austria. The corse was around 1/3 as large as I had imagined it. The quads simply tilted forward and controlled their speed by throttling up and down. The drag of the frame slowed them down quickly when the throttle was lowered. This was a huge advantage as they could control the speed without loosing visuals on the gates. The tricopter, meanwhile, more or less kept its ludicrously high speed and needed to be tilted back to slow down, making it very difficult to manoeuvre the course.


When I did make it a complete lap it was very quick, though. The problem was that I ended up crashing a lot as the gates came up a little too quickly. It seems like the race courses I’ve seen from other competitions are larger though, so this might not be a problem, except for on very small courses. (Any experienced racers out there that can confirm/deny?) But I feel I can’t call this a racing tricopter based on my experience in Austria.

The next problem is the yaw. On the larger tricopter the performance and feel of the yaw is superior to that of a quad in the same size (in my opinion). It’s a more natural, analog feeling instead of the very digital, mechanical feeling of a quad. The issue arrises when you shrink things down. The shorter arms and huge thrust range of these mini-sized copters forces the tail servo to work extremely hard. The result is that the tail on a Mini Tricopter doesn’t feel quite as locked-in as a mini quad or a bigger tricopter. It does these little wiggles here and there, mainly with rapid throttle changes. I’ve spent many many many hours testing different PID’s, TPA’s and firmware changes but I simply can’t get the yaw to perform as well as I would like.


For instance while doing a slow flip with the throttle reduced a lot, the copter might yaw a couple degrees and it might wiggle a little when punching the throttle again after the loop is done, or when doing very long vertical dives with very little throttle the yaw I term maxes out and it turns to one side
(I should be able to fix this by modifying the code, will report back on this).

When doing a lot of fast throttle changes you can feel the tail working, compared to a mini quad or bigger tri, where it you hardly notice that there is a yaw axis. The tail on the mini tricopter feels like there is a little gnome reacting to everything you do. He does a great job, but you can still tell he’s there. It makes you notice that the yaw axis is a factor where as in a mini quad you don’t.

The Mini Tricopter is still a bucket load of fun. It loves doing fast, long low-passes with big wide turns. Loops and rolls are very fast. It’s great at chasing other aircaft. It flies sideways and backwards just as well as the larger tricopters. Since it’s pretty aerodynamic it does cover ground fast without much throttle, which gives longer flight times with higher speeds than the typical mini quad can provide. Proximity flying between trees and such is also something it is really good at.  The yaw is crazy powerful compared to a quad. Overall it’s a really fun little machine.


I’m torn. On the one hand the mini tricopter is great fun, but on the other hand it doesn’t perform as well as I wished, nor as well as a mini quad. That is why I haven’t released the kit yet. It’s not great at racing, as it only has one speed when tilted – Insane!, and the yaw isn’t as good as on a quad. I don’t want to sell a product that people are disappointed in. But I might take this too far. The copter does fly well and it is a ton of fun, it just doesn’t have that super locked in feel on the yaw as a high-end quad. It’s also much more work to trim the PID’s on the yaw, if you do it from scratch. But I would supply PID’s that would be good for the recommended setup, so it might not matter as much?

I need your opinion. Should I scrap this project and move on to something else, or I’m I overthinking things? What do you think?


107 thoughts on “Mini Tricopter thoughts – need feedback

  1. Extra info for the technical guys out there:

    The mini tricopter has an unequal P factor, it always want’s to turn in the opposite direction of the two(or three) props spinning direction. This force is compensated by tilting the back rotor to one side. It work just like on a larger copter. However the difference between the larger and smaller copter is the motor to motor distance and the enormous thrust differential a mini class copter experiences. The leverage the tilt mechanism has mini copter is much less than that of a larger copter, so it needs to move more to achieve the same rotating force, but the shorter arms mean less force is required to rotate the craft. Sounds like those to problems take care of each other right? Well this means that the rotation of the craft is greater affected by the P factor (the force which the crafts wants to rotate around it’s yaw axis due to unequal number of rotating props) and the tilt of the servo needs to be faster and larger. The thrust range on these small copters are enormous. You frequently change between almost 0% throttle to 100%, and the thrust of each motor goes between 0g and 1000g. While changing the throttle the P factor also changes. So when quickly changing the throttle, the yaw servo needs to compensate for the P factor change. But the increased thrust from the tilting rotor when increasing the throttle is making the compensating power of the yaw stronger meaning that the PID’s might be too strong. This can be fixed somewhat using TPA (lowering the PID’s the higher the throttle stick is) (This also effects the pitch and roll PID’s) The biggest problem is when you decrease the throttle, the thrust from the rear motor goes way down and the servo needs to move a lot more. It can even max out without actually achieving the necessary thrust to compensate for the rotation of the craft in extreme cases. As soon as you increase the throttle again the thrust is increased and there is almost always a little bit of waggle. Airspeed also plays a huge roll on how much the servo should compensate. Simply put there is a lot of stuff going on to keep the yaw under control in a Mini Tricopter. Where on a Mini Quad it almost takes care of it self. When you punch a quad you get equal P factor and there is very little the PID loop needs to compensate.

    • Just a thought…….. Are Y6 racers allowed? If 6 motors are allowed for racing then I guess you could eliminate the yaw mechanism and get a more quad yaw feeling back. That won’t be as good as your original tri is with it’s locked in feeling. But I’m going off of the recent Flitetest Y6 build as an idea. It would just be a smaller version meant for racing. I am guessing you would have to change the kv of the motors and go to a smaller prop as well. That might also give you more room. Might give more run time as well? Am I close with any of these ideas? I would love a mini Y6 myself. I need a small fpv multirotor so I can put it in a case for travel. Please comment.

      • Yeah a Y6 would work. It would be less efficient as the bottom props would work disturbed air, but sure it would work. The flight time would be shorter as well. Smaller motors would be a must or the copter would weigh a ton. Some downsides would be price as would be running twice the number of motors, esc’s and props.
        You would also need a tall landing gear so that the bottom props doesn’t touch the ground during take-off and landing. It could be an alternative though.

          • Christian you have what I think is the best answer so far. V tail! Or maybe a tail. Which is more efficient? David can answer that. I thought I was onto something mentioning a Y6, but your answer is better. But, then I wonder if just building a quad is the answer after all if you have to add a fourth motor. Can’t see a V or A tail being more aero dynamic than a quad with as many surfaces. But what David has created looks similar to the MultiRc HMB 230. And that quad is almost bulletproof! If David adds his built in board then makes it with a forth boom and rotor it should blow the HMB away in sales. I’d buy that no matter what configuration he comes up with!!!

    • Hi David,

      First, thanks for your awesome videos and discussion of tricopters. I know this is a lot of work for you. It is greatly appreciated.

      I’m planning to build a small tri next. In doing some research I quickly came across your site. So I reviewed your earlier stuff and thoroughly imbibed this video and discussion.

      I think what you’re seeing is a cool multi-modal control problem. Control theory is my expertise, and I’m drawn to small tricopters because they have a unique control problem in “P”, which (I think) is related to the yaw axis acceleration ratio.

      Basically, the “azipod” tricopter design has a slower reaction time than the spin acceleration of the front blades.

      This difference is amplified with shorter baselines. Somehow we must rebalance this ratio of reaction times.

      What would happen if you used a shorter three-bladed prop in the back? Three bladed props must spin at higher RPM for equivalent thrust. The smaller, faster-spinning blade may help with both progression effects as well as faster servo response (shorter lever arm.)

      I’d be really interested in your experience with a GWS 5x3x3 on the back, perhaps balanced with slightly longer 2-blade props on the front (if possible.)

      BTW I’d buy the frame and try some of these things out for myself!

        • Oh. You mean GWS doesn’t have enough stiffness? Didn’t think of that – thanks.

          Please let me know what you find. I’d like to match it here. I couldn’t find a lot of choices for 3 blade. But I recommend that the 3 blade be shorter and have less pitch than the 2 blade equivalent.

          Most fixed wing props are 3 blade so they can be shorter while providing the same thrust. But they need less pitch to counteract the loss in top speed caused by trailing-blade cavitation.

          In theory a 3 blade tail will provide faster progression performance, providing shorter reaction delays, making the vehicle more controllable in yaw.

          I’m honestly not sure, but I’m working on a blade test rig and will have some plots soon.

    • Did you know that in CleanFlight 1.9 there is a setting in CLI that helps with twitchy yaw servos on tri-copters? It’s yaw_jump or something like that, I don’t exactly remember the setting but it completely fixed some yaw problems I was having with a giant 850mm scratch build. Also, a couple of other things, use a digital coreless servo and set the pwm rate to around 150. Seems that every frame has its own unique problems/setup. I’ve also tried different size props on front and back with sometimes good results(I have built six Tris, including a mini cf frame and one of your frames). The 850 has 11×5 cf props and runs on a 6s battery. It’s so fast and agile for it’s size that it is almost scary to fly!

  2. David, the frame is a great innovation. Even on a full sized tricopter it would work great in protecting GPS and so on, as well as provide a platform for the board camera.

    I have flown the mini tricopter for a while now and have experienced the exact problems you describe – but wrote it off as incompetence in handling and tuning the PIDs 🙁 I have flown the frame with small and bigger motors on 3S, and the bigger the motors, the bigger the problem with tail wag in my experience. Cleanflight is not tuned for tricopters. The problems you describe are spot on, and the code should compensate not only for the tricopter layout, but also for the torque of the motors. It does not make much difference to a quad since the motors cancel each other out, but on a tricopter it does. The code does not even take into account the rotation of the motors. If it did, it could utilize this rotational force and use it to its advantage. Until “someone” alters the code for tricopters to include racing tricopters, it still is a great little platform.

    Long story short: Release the kit – with the disclaimer. Even if it is not a premium closed circuit racer, it is a really great pocket sized camera platform. The community might succeed in making it a racer if we get our hands on it 🙂

    – Keep up the good work!

  3. Hi David. I’m flying a homemade mini tricopter on 3s it’s about 250 size. It’s small and light and it a bit “twichey” and has the same issues that you talk about. But it’s sooooooo much fun. I’m not into racing, just messing about with rolls and flips. With full throttle yes sure you get a bit of wobble and I’ve been unable to get rid of it, but it’s perfectly controllable. Looking forward to it coming out. I’m gonna have one. I’m in the middle of the naze32 tricopter frame build at the moment

  4. How about you just release the canopy kit with instructions how to change the normal tri to a mini. The canopy looks like a good idea even for the full size tri, so if someone wants to change theirs into a mini he/she can, but doesn’t have to, meaning you are “covered” 🙂

  5. I think that we really cannot make it fly like a quad. From the nature of the design, a tricopter flies differently than a quad. So maybe we are aiming at the wrong idea of comparing it with a quad especially with the flight characteristics.

    I suggest that you release it. Lets continue to fly it like a tricopter. Maybe firmware changes can address it if someone would focus on it. If we would put the same amount of effort on revisiting the codes to make the yaw better, then eventually we’ll get the same flight as a quad.

    Im with you on this david.


  6. Maybe shimming the motors to get a bit of a ‘bowl’ effect helps?

    Anyway, I would like to have a mini just because it’s less intimidating for the public. Is it possible to release some footage to see what it’s capable of? Then we actually know what we are talking about. No need to edit the video or anything, just post it on YT unlisted.

  7. Jag byggde en minitricopter helt efter delarna du designat för ett par månader sedan. Den flyger mycket mysigare än mina quaddar med en härlig känsla av “bakhjulsdrift”. Problemen du beskriver stämmer mycket väl in på vad jag märkt själv vid hårda punchouts och liknande, den svajar fram och tillbaka vid hårt pådrag, samt att den går väldigt fort när man tiltar fram den. JAg skulle personligen gärna se en release på din version eventuellt delar för att konvertera den större versionen till den mindre ifall du väljer att slopa kitet men när du hintade om den för ett par veckor sen så tyckte jag att du var precis rätt ute. Det finns inte några vettiga tricopterkit i nuläget för racing eller “mysflygning”. De från Hobbyking är för klumpiga och din design slår allt med hästlängder nu med det integrerade naze kortet. Eventuellt skrivs koden om och förbättrar yawservots slit inom en snar framtid vilket bara skulle göra alla oss tricopterflygare ännu gladare, men tills dess så får man väl bara inse det att quads är snäppet bättre på banor, medan körglädjen är större i tricoptern!Så jag skulle köra på och sälja tricoptern i dagsformen med reservation för det du skriver om yawproblem. /Robin

  8. Hello David, i love the Tricopter V3 and i would sure buy a Mini Tricopter Kit!

    I understand your concerns but i think with a clear description what this thing can do and what not everybody would be fine.

    I think there is a good change that after release there will be some tweaks in the PID, and i think we even would get used to the special kind of flying.

    Let me suggest you something:

    What about a poll who would buy that kit at this state?

  9. I would love to see a conversion kit to buy. I completely disassembled my old tricopter but I still have the Naze frame, PDB, ESCs, tilt mechanism so building one with just the extras would be super cheap. So even though the issues are there, I get to use some parts which would just collect dust.

    One thing I am curious is if you have tried higher KV motors such as the Cobra 2208 or even the new insane Cobra 2213 2000KV (just think of that speed).

    To answer your question. I would say that I really want it, I already have a quad for racing so why would I want a tri for that? I want it for soaring around large areas while being compact enough to take with me in a backpack on my bike (I don’t have car).

    Another thing you could do is convert to a quad by converting the base to a similar x shape (mirror the top half I guess) and move the components slightly back and there are still plenty of great design features which will carry over.

    Regardless, I and everyone else here really appreciate the work you put into this design and I hope we can work something out.

  10. Hi @David !

    First of all, I just want to thank you for all the efforts you put to make our experience with the tri better. I think you are as perfectionist as genius, and you are an incredibule genius.
    You want this mini to be 100% if not 150% perfect for us wich is amazing. In biology, we say that there is no signifgicatif difference between 95% and 100% because 5% is nothing. I believe your mini is 99% perfect and most of people (me included) will not see the 1% not perfect, because it’s not a significatif difference. I don’t know if it makes any sens 🙂

    Now, if you find the mini to fast, it’s mainly because their quad are too slow ! No, just kidding, but maybe a 3s setup may be the way ? I am currently flying my mini on 3s and I reaaaaaally loving it ! I haven’t pushed it to it’s limit for now, but I’m having a lot of fun.
    I didn’t really understand all the technical parts you wrote but could you share your PID so I could try it on my 3s setup ? For now I’m using the PID you provide with the integrated Naze and it flies great. I have some oscillations but nothing too bad, I just have to decrease some P gain.

    Also, if I unterstood right, the tail has to work harder to yaw because boom are shorter so the servo work more when giving more throttle. Could it be possible to make the two front motor spin in the same direction and the tail one reversed ? so the torque produced in the front would yelp the yaw ? I think I just wrote something stupid but I leave it here, we never know 🙂

    I was listening to the Flite Test podcast from the start again, and once you said :
    “Release the Kraken !”
    I think now is the time for you to say :
    “Release the Mini !”

    Don’t worry, we’ll love it and crash it as hard as possible !
    I love what you do, keep going, make again some crazy project as you use to. I really want to see the assault char with paintball on it ! I’m thinking to put an EDF on my mini, or regular sized tricopter, it’s going to be a lot of fun !

    Again, thank you !
    Take care

  11. I don’t have an interest in racing. I love speed and big turns. I’d buy the kit for sure. I think you should sell the kit with a description of flight characteristics. Perhaps there could be a tri racing class with longer courses. It looks and sounds great!

  12. So the question amounts to if there are potential customers? I am one of them, flying such a fast thingie should be a very challenging and joyful endeavor! 🙂

  13. Hi David, first of all, great work on the mini, it look really cool.

    If you are having problems with the yaw, you can try a kind of idea I’m experimenting with, I set up a mini T-copter, 250 size, with a tilting mechanism on all the motors, this works on 2 ways:
    1- The motors can tilt forward to increase the speed.
    2- The motors can tilt opposite sides to help yawing the copter.

    I guess on a Y tricopter you could put all the servos to the same signal and get crazy yaw, it’s just a matter of trying it.

  14. Hi David,

    Is there room to put a larger prop on the tail? Maybe the increased disk size would ease the work load on the servo. And it doesn’t sound like you want to make the mini any faster, so perhaps drop back to a 3S, or maybe lower kV motors.

  15. Hi David,

    Is there room to put a larger prop on the tail? Maybe the increased disk size would ease the work load on the servo. And it doesn’t sound like you want to make the mini any faster, so perhaps drop back to a 3S, or maybe lower kV motors.

    BTW, I love the picture with the tricopter stuck in the race flag.

  16. Hi David
    Firstly thanks for getting me into this great hobby since I saw your tricopter I wanted one,with your great videos and support I have learnt so much and enjoyed flying.I brought the first tricopter you released and built it with the kk2 board I learnt to fly with this but wasn’t very good at adjusting PID myself .BUT I just got back from the first flight with the naze32 board and my Tricopter is on rails it’s so smooth!!
    I think what I’m trying to say is we all appreciate the work you put into your products but in time I’m sure
    with the help of the guys who purchase your products and the community it can be improved,we all want a mini so stop worrying and stick it in the shop!!

  17. This little thing just look amazing!
    I´m sure it flies awesome, and if you put it the shop more mini tris will fly out there and the demand for a change of the code will increase. And it would be really cool to see a class of tricopters racing.
    I think it would be like multirotors F1 series!!

    “Release the Mini!”

    Thanks David for all your hard work!

  18. Hey David,

    I’ve been a a fan of your products since the first hour /(still need to put the signed plates to some use now after the naze conversion, but thats another story). The mini looks fabulous! Since I’m still in the process of learning to fly, I haven’t yet reached the limits of the big one. But speed seems to be addictive. So it is obvious for me to opt for the mini, as soon as it is released.
    From my point of view, I don’t thing, that I’ll notice the minor glitches of the mini. And even if I would, I don’t think I would mind. Since flying is so much fun. But as an engineer, I can understand, that you don’t want to have a project kinda half finished sold / defined as finished. That sucks and does not leave you behind with a good feeling. On the other hand as a hobbist, isn’t it supposed to be a hobby and therefore never ending by definition?

    So, to go with @johnny jacobsson: “Release the Mini!”

    Greetings from germany and keep up the awesome work!

  19. Hey David,

    I’m not a big fan of racing but I would love to have one of these. It looks awesome! Did you try going with less power as far as the speed? I know it must be frustrating to not get the same level of purformance as the full size but I say definitely don’t drop the project.

  20. Hi David,

    I agree with all the folks on the frame additions and protection. If you don’t release the mini, at least release the frame enhancements.

    On another note, have you spoken to Dominic regarding the changes required in Cleanflight? Send him a prototype so we can see if we can’t get it to behave the way you want. Better yet, come to the UK in September for the Festival of Flight and we can all discuss it there.

    You might not remember but you got to fly my mini v-tail last year in the UK, how about changing your mini to a v or a-tail? You’d still have improved yaw authority but the torque issues should be negligible then.

    • Not a bad idea to see what Dominic thinks of it. I’ll send him a message.
      I toyed with the idea of making it into a V-tail, but I’m concerned about the strength of the mount. I can use 2 separate arms as the power distribution board would short out. A mount that sits on the 10mm boom might work but the torque put on the tail would be immense in a crash :/ Especially as the mount would need to pop the motors up a bit so the props don’t hit the ground.

  21. please release it as a kit.
    #1 quads dont fold up.
    #2 quads don’t go 100 mph.
    Again please release it. I have been looking forward to this product for a long time.

  22. I’m loving flying my RCExplorer style mini that I built. It great fun and really durable in crashes. I agree with every one else, release the mini. It may not be a racer, but I pretty certain I’ll really never be racing it. I just love the mini size for flying around and fearlessness.
    On another note did you try a lighter setup that might handle the corners better?
    I certainly am in line to buy one.

  23. @David, have you tried running the mini-tri backward? I know the folding will have to change. I think it might change direction quicker. What do others think?

    • It works just the same flying forward as backwards. Since you fly at a 45° angle the airflow is almost the same when flying forward as back. Good idea though 🙂 It’s reaeeely weird flying it with the tail first though. Takes some time for the brain to get use to the look of the thing.

  24. Just thinking “outside the box”: add airbrakes that extend when you lower the throttle to slowdown for tight turns for racing. The bad side is it will add more complexity.

  25. Fly it like an aeroplane in rate mode and it corners just fine… until the tail freaks out. It is not the breaking and turning that is the problem, it is that the yaw servo goes into a tail wag loop. The flight controller needs to anticipate the force it needs to apply (or not apply) to the tail motor and servo when doing a turn. On a quad the motors don’t shift their position, so the force applied to them can be calculated on a linear curve (if that makes sense?). When the tricopter turns, the rotational force of the rear motor changes in relation to the tricopter. The code (I assume?) does not take into account that yaw to one side behaves differently than the other. So compensation to one side will be too weak and to the other too strong. You get tail wag.

    • I’ve never had the Mini Tricopters loose the tail or get into a bad waggle during a “race” so to speak. I’ve got that trimmed out. You can be really aggressive in the turns and it holds fine. It might wag a couple of degrees but not more. Low-pass filter, and D term took care of that 🙂
      Yeah I hear what your saying about the code assuming the yaw is equal on both sides. Wonder if this could be fixed, since it can be very different on different setups.

  26. Hej David,

    first of all thank you very much you are doing an amazing job.
    I also think you should start selling the kit.
    I’m quite sure that the Tricopter support in Cleanflight could be improved if more and more Tricopter are on the market.
    May be other user of your Tricopter could find ways to optimize the behaviour, but therefore you have to sell it.
    You should send a kit to Dominic, I’m sure he will love it and help to improve Cleanflight.

    Hej då,


  27. Thank you for your great feedback everyone!
    I think what I’ll do is make a limited run of the kit to get it into people hands so they can experience and trouble shoot as well.

    The kits should be ready in 2-3 weeks if nothing goes wrong along the way.

    • Thank you 🙂
      I’m not sure how helpful I can be with my limited experience with tricopters, but I sure can help with the durability test 😀
      Eagerly looking forward to it.

    • That are good news. 🙂 I like it. I’m in! Can I “cheat” an place a pre-order? 😉
      Lets hope I don’t miss it…

      David keep up to good work! I really appreciate it.

  28. Just a wired thought. What about having a tilt in all three motors?
    So what you are saying is that the mini tricopter kit will only be available for a limited amount of time and then be gone for good ); ?

    • I’m not sure whether that would be helpful or not. The tilt is powerful enough on it’s own. It would mean that you get less resolution as even a little tilt would have a big effect.

      I was thinking I would do a limited run and we’ll see what people think about it. I can kick up production again if we sort out the issues and people like the copter.

      • I have been playing with the thought of having the the tail rotor static and putting a servo to the both front arms. The signal to the other servo would need to be reversed in code and use the second servo output from the naze for that.

        It probably won’t fix the tail wag problem and would introduce other issues (additional weight, more breaking parts etc.). With huge cleanflight changes the two tilting front motors could be used to gain forward momentum without tilting the copter.

        It would be fun to try at least;)

        • I’m working on that very same idea. I have set up a mini tri with the three motors tilting so I can test the behaviour with different tilting setups.

          Right now I’m using 100% throw on the tail and 50% at the front (so I don’t ruin my resolution). It feels nice, very alike the big one when yawing, but I still need to adjust the PIDs because it gets wobbly sometimes.

          Maybe I’ll give a try to the idea of only tilting the front motors, and see how it feels like.

  29. Looks like the editional frame is something usefull for the big v3 version as well.
    As someone mentioned before release it as a addon and make a build plan for the mini and have the nice motors etc for the mini in your store.

    Let the racers do there thing with it.

  30. Hi David,
    1. Thanks for your tireless work. I really enjoy flying the carbon TriCopter.
    2. Don’t some helicopters have a fin/wing on the tail rotor? Maybe link a fin to the tail servo? It could be below/behind tail motor.
    3. Release a limited run and let everybody join in the debugging.

  31. Hello David,
    What PID controller are you using for the mini tricopter? PID controller 0 is old and slow, is it possible to possible to try PID controller 2 (LuxFloat) it utilizes the 32-bit processing power of the NAZE also combined with oneshot you can reduce the looptime to lower than than 1500 a very smooth and fast response.

    Boris B has a blog in RCG with a new cleanflight hex file that improves the luxfloat controller, people are using looptimes around 500 ! I think it’s worth it to try to optomize PID controller 2 for the tricopter.

    this is the link to Boris B’b Blog in RCG

      • 1500 = 1500 uSec ? mSec ?
        LPF – single order ? other ? what is the pole ?

        I feel(or I actually know) that the available features in the controller are very poor.
        you should very easily achieve superior results with the correct control strategy and controller

  32. Despite the minI tri not being perfect for racing, it sounds totally awesome otherwise. I’m a filmmaker, and I’m just imagining the possibilities of sending a gopro at speeds upwards of 80 mph. Also the mini tricopter frame thing could be used on full size tricopter a as well. I noticed it’s not on the store, but put it on there as an experiment, or concept.

  33. Hi Dave,

    ? Keep it simple: torque designs needs better stabilization on air flow – tilting your forward arms (~7º inbound, pointed to it’s COG) and back arm (~7º forward pointed to its COG && ~3º right – this arm must be a little longer than the others! ~20mm will do the right torque!) will shurelly improve bad behavior that you get on the race track && left turns will do it steeper && stable – just check on Chinook heli project;
    ? After that – only when all is merged on its position, so you’ll need some software fix…

    Best &&
    Keep the good job!

    Fábio Romano,

    Obs: I had my first flight on your ‘regular’ tricopter frame last evening – and this strange behavior evolves as its tendency to tilt left on axis (~6º) – so, as the velocity increases && airflow keeps the laminar flow unbalanced and turbulent, all left turns must be done closed to a stop or it flips!

  34. has anyone else noticed that the esc are nowhere to be found on the setups. It’s truly an amazing design that captures all the beauty and aerodynamics that a mini tri should have. Keep up the amazing work David

  35. Hi David, I also really want a mini tri to work. It would be the perfect mix of elegance and raw power 🙂

    I think a redesign or alternate use of the tail mechanism may help you. Let’s see if I can explain…

    The issue is related to why you may have experienced a tricopter giggling on the workbench with the servo going back and forth and the motors low or off.

    Think about it: Your tail servo mechanism has the center of mass of the pivoting motor and mount above the axis of pivot. This means that a small bit of mass at the end of the back arm gets thrown counter-clockwise when the flight controller orders counter-clockwise yaw. When this small mass gets thrown in the intended direction of rotation, the rest of the copter gets nudged in the OPPOSITE direction (conservation of angular momentum). It takes the spinning back propeller (now angled counter clockwise) a moment to correct for this unwanted nudge and move the copter counter-clockwise.

    So this behavior could be avoided by redesigning the tail mechanism so that any servo motion would not change the center of mass of the tail arm (and affect the rest of the copter). The center of mass of the tilting parts (mostly the heavy motor) would be aligned with the pivot axis of the servo. This is a link to a picture:

    Other option is to use the same tilt mechanism you have but put it on upside down and reverse the thrust of the prop. So the motor swings below the arm. Then, moving the servo would nudge some mass in the direction opposite of the intended rotation. This would HELP rotate the whole copter in the intended direction. But now you have an upside down prop and would need some weird landing gear solution…

    I’m not sure which option would work better. Best of luck!

    • Though maybe the odd number of props is still the main reason for your difficulty, I can’t say 😉

      But with the different tail design you might need much less or no servo filtering in software. And that might help with yaw precision.

      • Very nicely explained
        This is indeed an issue that comes into play as the arms get shorter

        I sm not sure inverting the motor is a good solution since you will need to add landing gear and become less crash resistant , but somthing like the brocopter’ s solution will help

        • Agreed, the upside down tail mech wouldn’t be a good final solution. But it’s something someone could try immediately to gauge flight characteristics. Just have to carefully launch it from your hand or something 😉

          yep the brocopter design is nice…

  36. Hey David, and gang! Lots of good ideas here David!
    So I’m just gonna spit ball one as well.
    Not sure is anyone else has mentioned this, but If there were a “stabilator”, or a rudder, in the prop wash of the aft tail rotor, that tilted or deflected opposite the prop tilt this would in fact increase your yaw. You could accomplish this movement by taking a spur gear from the RC car world cut it in half, then take each half and face or mesh the gears. This would give you the action you need to couple to a rudder.
    Just an idea!!

  37. Hey David! Sure miss you on FT but Congrats on all the amazing things you’ve been doing on your own. You are truly a gifted contributor to the hobby!

    Everyone seems sure excited about 100mph mini tricopter but my though was that perhaps it’s just over powered. Those quad racing courses are won on maneuverability, not all out speed. smaller props might help as some have suggested but maybe dropping to 2204 or 2206 motors might take a little of that punch out of it. I would think you would lose that “swoopiness” feel of a tricopter if the tail is reacting so quickly with so much power.

    other mini tricopter frames are being run off of 1806/1400kv motors on 7″ props with great results. certainly they aren’t racers, but I would much prefer to put ANY power setup on one of your designs versus another.

    Anyone who has been following your blog has been anxiously awaiting the release of your mini tricopter. Even if it isn’t the best racer you’re likely to get great feedback from your fans and maybe find the right set of motors or settings that will turn it into a racer.

    Good luck!

  38. Hi David. I’m running a similar setup but with a rigid front single arm to form a t-cooter with your name plates.
    Running 3s with 5045bn props from gemfan, 1806 2300kv t-motors, blheli dys16a and your tilt and servo.

    I’m finding the same thing as you with yaw wag occasionally especially under hard power changes, I found it got a lot better when I stopped using 6030 props though.
    I’m running mine at the minute with the ‘cage’ slung under the body but am about to do a complete rebuild after a dodgy battery plug dumped it in a pond and am considering reconfiguring it to move the cage and components to above the arms.

    I’ve raced mine a couple of times now and at the first meet it was just waaaaayyy too fast for the tight course. The latest race meet though was a much more open fast course with bigger gates and there the quads just couldn’t keep up!
    I ended up reaching for my quad at the first one.

    Anyway, my point is that there seems to be a multirotors for every occasion, horses for courses if you will. I’d say release this but billed as what it is, a very fast open fpv craft.


  39. Hey David,

    This is just an idea but, I have seen some tricopters with the tilt mechanism under the boom instead of at the top. Now I haven’t really tested or calculated if this would work but, sometimes the simplest solutions are sometimes the best.

    Thanks for making the tricopter btw, its really fun and awesome.

    Ambrose Cartwright

  40. Underbar ram. Gillar starkt att batteriet sitter skyddat.
    Så det blir att pensionera min armattan mini trikopter till förmån för denna.

    Du råkar inte arbeta på ett nytt kort med f3 processor och inbyggd osd? Alternativt pdb med strömsensor?


  41. I think that you should go ahead and at least release plans (CAD files [if you want to, I mean you’re still planing on selling kits], patterns, etc…) for it and a limited quantity of the models and let people just start flying them, almost as a Beta test. Who knows, maybe they’ll find a solution for the current issues. In the meantime keep working on it and when you have everything figured out, then release the “final” version.

  42. I’d say, release it. But with the “warning” as you have in this post..
    And hope for the Naze code to get better aswell.!

    Like the new design with the “canopy” etc. Hope to see this in the near future! =)

  43. In a way, I’ve paralleled your development with my own little mini tricopter project, made from hobbyking parts and an AfroMini Naze. I took three carbon fibre 100mm-long square tubes and used two CF motor-mount ‘disks’ as the hub (a few screws just clamp the arms between the disks – arms are not drilled) and the Hobbyking ‘vector thrust’ tilt mechanism with the motors sized to that, and 12 amp afro ESCs. Everything was built essentially as a 1/3 scale model of your big tricopter with wires internal to the arms, although that did mean 6×4.5 props since that’s about 1/3 the surface area of the 9 inch props. Came out about 180mm hub to hub, 250g with batt, No FPV equipment. With a 950mAh 3-cell, I get 10 minutes flight time, 12 if I push it. Hovers on 25%. Lovely little machine.

    So yes, little tricopters are crazy powerful as you’ve learned. But also agility also goes up as inverse of the third power of linear scale, so there’s a vast increase in agility, so even though my tilt servo is restricted compared to the big one, I can spin like a top. The little one even deals with cross-winds far better. Less ‘squirrely’ that the big one, which now feels like she’s got a fat ass in comparison.

    But I know what you mean about the little gnome on the back. You get used to him, and start banking the turns a little early so he isn’t thrown about so much. I actually wondered if it might be good to mount the tilt motor pointing _down_, so that the weight shift of the tilt is complementing the intended motion, rather than opposing it. (Or sitting the motor in some kind of ‘sling’ which moves the tilt axis up towards the prop, so the motor tilt creates no weight shift.)

    Incidentally, I notice you’ve moved the ESCs into the main body… I think that’s where some of your flight time went. I know they’re exposed out on the arms, but I suspect the power savings are worth it. V=IR is bad enough with those currents, but there’s the inductance too. You want all the wire you’re driving to be _inside_ the motor. That was a big advantage of the v3.

    I don’t think a mini tricopter is ever going to fly exactly the same as a mini quad, nor should it, and that’s fine. I’m often amazed they fly as well as they do already, given the poor state of the flight controller physics for their special quirks. They’re still smoother, “swooshier”, and there are major mechanical advantages to dropping an entire arm for the cost of a servo.

    I still think the yaw mechanism gives more ‘overhead’ on the main motors than quads do, so you’re not losing one of your degrees of freedom when pushing the throttle hard. Also, not using motor torque to turn the quad puts a lot less stress on everything, especially the props – I’m still on my _original_ props, held on with rubber bands. I’ve never exploded a prop mid-air like quads seem to, and that thing’s probably had >20 hours of flight time by now.

    Lastly, I’ve learned a few tricks that might help with your racing. eg: I’ve learned to yaw my ass around abruptly and use the prop disk effect as a brake-stop.

    In conclusion, I think you should release the pieces with a big “Experimental” label slapped to them, and we’ll work it out. Especially the short arms!

    I’ve been waiting for short arms! I really don’t want to hack up my existing arms, and between the spare tilt upgrade you sent, spare motor mounts and landing gear, and my original top/bottom plates, I’ve got most of what I need to slap together a new one. I’ll bet a lot of people do.

  44. Hi David, I’d love to get one of those bodies for my 290mm Y4!



  45. Hmm… I just had a look in the debugging forum, and one person suggested a fix that I forgot I already do…

    David, I suggest you try switching the rotation direction of the forward arms. I did this because I wanted my mini to ‘bounce’ off tree branches rather than pull them inward when flying proximity. I wasn’t going to go fast, and I didn’t care about tip-stalls. (Frankly, I don’t see them being that much of a problem anyway – the lift just shifts to the inner edge, and there’s not that much difference in leverage…)

    I just realized I did the same thing with my original v3 build, but after I got the new Naze/PDB plates I switched to the ‘standard’ layout… and ever since then I’ve had a few ‘squirrely’ issues I’m sure weren’t there before.

    So, maybe the common wisdom is wrong, and mini tricopter forward props should spin outwards. Give it a try! Works for me. (Or at least, doesn’t screw me up.) You should be able to notice any subtle differences better than we would…

    • Oh, yeah.. the theory suggested is that the torque direction you get when going CCW-CW-CCW for Left-Right-Back better compliments the actions you do in a banking turn. My mini has that configuration, and seems to fly better than the big one, which has the usual config, so at least the theory’s not completely disproved by practise.

  46. David first, I think you are “overthinking the matter” have you tried to race a quad yourself…. it looks like it is the same for the racing quads too… you never stop flying ahead or else you loose whatever you are flying towards 🙂 its just how things work at 45deg angles.
    Second, I think gopro will fit nicely inside the cage if you tilt it 90deg than tilt the frame back in the post production.

    Also, if you ever get to manufacture those, please make the “cage” so it can be opened up easily like a robocat (if not familiar google 250 size robocat). I think it should be pretty easy to achieve by changing how the cage is attached to the frame on the front and will add 5-10g at most- just run bolt across the frame spacer from side to side. This will add structural integrity to the cage as well as allow it to “swivel” to the front once the top 4 screw securing the cage to the from in the back are removed. this will grant full and easy access to whatever is inside the cage.

  47. I have been blessed with a pre-production version of the “cage” and have been testing it for a bit. The modification you suggest I have already done to test it. It is easy to retrofit, as all that is needed is to drill a 5mm hole through the nose spacer (to fit the existing spacer) and drilling two 3mm holes in the cage to fit the M3 screws through.

    That being said, you would need to remove 4 screws to open the cage. In the current design by loosing the two camera screws and the bottom screw the front of the cage can be easily removed for access to camera etc.

    • Terje, why I suggested the mod is because based on the pictures alone the cage is also attached to the front of the frame via two “ears” and it seemed that in order for the cage to “slide out one must either stretch it a bit or to loosen/remove fasteners which held the two half of the cage together. this observation and suggestion is based strictly on the pictures posted here and as you have the access to the cage you must have better perception of how it works. and yes, I did think about using a spacer instead of the bolt, but I was not aware of the exact size of those red spacers so I didn’t know how easy it would be to source the exact size needed and in David’s “simplicity sake” style I suggested a simple bolt.
      Regardless, either 45mm bolt+nut or a spacer+2bolts it is going to add structural integrity to the whole thing I think we can agree on that 😉

  48. This looks awesome! If you make a limited run I will certainly pick one up. Love the concept and looks. I’ve had a couple of small tris so know what I’m getting into…but they’ve been 3D printed and not robust enough for racing. This looks ideal!

  49. Interesting problem… A few thoughts. You could use a longer tail boom. This would give your yaw a greater mechanical advantage and still keep the width of the copter narrow allowing you to navigate the racing gates. The design would be more like a dragonfly. You could couple the servo to the yaw mech with a stiff tube to keep the CG closer to the front. Or you could use a fourth motor as a tail rotor. This technically turns your tri into a quad but would solve the problem. You could put a small rudder under the rear motor to perform the yaw function. You would still have the same “swooshiness” but could avoid all the problems of tilting a motor that is also trying to provide lift. You could use a rudder under each motor with a three way linkage to one servo but you would lose the “swooshiness” and it would turn like a quad. Very robotic with no graceful curves… just rotation. I think the easiest way would be using one of your full sized booms for the rear and moving the battery and other components forward to compensate. This would be a simple mod using the stock components you already carry. Easy to add to the store. Please call it the “Dragonfly” if you do it!

  50. Hello, I want to build this kit and try to convert it to a ap mini tri, the motors that come in the electronics pack, can they spin a 10.47 prop safely with out damaging the motor?

  51. Hello David,

    Thanks for the interesting article on the mini-tris. Regarding the camera orientation problem on tight turns, etc., do you think a self gimbaling camera, or a camera with a gimballed mirror (if one exists) might help?

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