Hi Forum, I am a fairly new user to APM2 (made about 4 successful flights on a skywalker.) And I am looking at building a twin boom aircraft for taking Aerial Pics to be used for GIS, land surveying etc.. I initially built an off the shelf twin boom called the URSUS, but due to its wooden spa construction, it broke in half in mid air. I have added glue, carbon and ply reinforcements, but now its too heavy to fly. Therefore I thought i'd try and build something myself using its power system

Here are my objectives

  • Must be able to accommodate a roll gimbal (I made this for the URSUS)
  • Must fly for 45 + mins
  • Must be shower/rain proof
  • Must Fit in the back of a Volvo V50!
  • Must be able to fly slow or fairly fast into wind
  • Airframe without power system should weight less than 1.5kg (based on weights taken from other airframes in this size range)

Based on some research, I have discovered that aircraft in the 2.2 - 2.6m range can achieve this. I have a moderate amount of building experience, using polystyrene, depron. But have never tried to build anything that performs well. 

I am going to make the Fuse out of fiberglass, and the wings out of EPP. 

Some technical details...


  • Wingspan - 2200mm
  • Chord - 250mm (giving an aspect ratio of 1:8.8 )
  • Profile - Clark Y (noticed a lot of these aircraft use a clark-y profile)


  • box section - 120mm x 120mm x 600mm (excluding nose cone and tail cone)
  • Booms - 51cm, From trailing edge of wing to start of vertical fin

Power System

  • Esc - Castle Creations Phoenix 45
  • Motor - Ultrafly F/18/10 1000KV Brushless motor (model number uf-mtr-f1810)
  • Prop - 10 x 7
  • Lipo - 2 x 5000mah 3s 11.1v

Some pics... there will be a nice cowl on front and back of fuselage, but i cant do that with my limited CAD skills! 



This thread and idea is a product of realizing that the lower end off-the-shelf airframes are not capable of what I want to achieve. I have reached that conclusion in my Arial Photography thread here.. The Skywalker is great, but can't fit a roll gimbal in it (I keep getting pictures at different angles). The Ursus is nice, but the construction is too weak for my needs. Whilst working on a new airframe, I will be continuing to use the overweight ursus to perfect my roll gimbal. However a new airframe is needed to get longer flight times. I quite like the medium priced hugin, but thats a little out of my price range right now. 

I can get EPP wing cores cut for £40, and a fiberglass fuse made for next to nothing.

I have a few questions - 

  1. What distance should there be between the booms?
  2. What is the best aspect ratio?
  3. What thickness should the carbon booms be?
  4. What height should the rudders be?
  5. Is it best to go with an inverted V or H tail?

If anyone with aerodynamic knowledge has any fairly simple calculations to see if this will work, please could you let me know! or any other thoughts for that matter, positive or negative!



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  • Please, let me know when you have the complete info about the plane!

  • Just made a catapult launcher for the flying wings - I wonder if I could modify it to launch this!!! 


  • Just in case anyone is interested, but i've started a new thread in the Aircraft platforms forum to do with using flying wings for Aerial photography. I'm going to persue this avenue for now. And plan the new twin boom design in the new year...


  • Quick question. I'm having a few issues with the APM tests I am doing on the bench. As soon as I power the APM on, it is in manual mode, which is great, and i have full control over the surfaces. However after about 20 seconds, or around a minute, I lose all control between my 35mhz tx and the plane. however the servos are still working when i titl tthe plane on stabilize mode. 

    Due to this issue, I am going to buy a new tx/rx for the test plane. I suspect it could be to do with signal issues, plus the Futaba 9c i am using has a faulty screen (a number of lines are missing).

    I am considering going with a long range system, What long range systems and transmitters so people use for APM? Or do most people go with the Expensive Spektrum 7/8ch tx's?


  • Cheers for the kind words chaps...

    Just need to build a transportation/storage box for it now...and integrate APM2 of course!


    It folds down into 1000mm (L) x 330mm (H) x 550mm (W)

  • The plane has taken off, flown around, and landed with no problems, no breakages either! 

    Wind was about 10mph, gusting to 15mph-17mph, but felt a lot stronger when it was up there. It was also raining a bit, but as we'd driven there, completed assembly and done pre-flight checks, it had to be done! A bit of duck tape over the motor wiring, and it was pretty much rain-resistant! 

    The 2 large rear wheels helped a lot, and it rolled much better after a bit of a nudge on take-off, just need to replace the nose wheel for a 110mm/85mm diameter steerable wheel. 

    It rotated after about 30 meters or so and climbed very well on 80% throttle. It had very docile flight characteristics, and no nasty stall tendencies. It maintained altitude at about 30-40% throttle, but flying into wind required a bit more throttle.

    Final approach and landing was a fairly straightforward affair, but mindful of the weaknesses in the main landing gear, i decided to go around for a second attempt, just to be on the safe side. It glided very well indeed. but I would like to do the next build a bit lighter, I could probably hand launch this if it were a bit lighter as well.

    The Video...

    I have definitely learnt a lot about airframe design, and construction techniques during this build. And this plane is by no means perfect. I am going to start gathering materials for the next airframe over the next few weeks, and commence a new build in the new year.

    I'm thankful to everyone on here who has given me valuable hints and tips along the way, and hope to put all the information and feedback to good use in the next build....

  • Small update - haven't done anything more on thew twin. just waiting for the weekend before I try and fly it! 

    I've been doing some more work on the wing with the APM. I haven't used the APM since it turned my Skywalker inverted at about 10ft AGL! - IT then dived and broke into lots of little white pieces. I have been cautious about putting it into another nice airframe, but as the twin is almost ready for a bit of APM, thought i'd retest it in something a little less breakable. 

    I believe my last crash was caused by something called a brownout. I was powering the Servos, RX, and APM & 3dr by a single power source on the output rail. I have since read that its a good idea to provide the rx, apm and 3dr power from the input rail, and then provide power to the output rail for the servos. So I am going to try this. May even tape a camera onto the underside of the wing if all goes well and see what happens.

    Just a few questions regarding power systems for the flying wing (AUW is 1500g including Canon Ixus80 camera, 1300mah lipo for rx and apm, 2200mah lipo for motor)

    I have two different motor and prop combinations I would like some help with...

    1. 2217-6t 1500kv, 8x4 prop = 6mins 46secs flight time on full throttle, 940gr static thrust (72g)

    2. 2217-9t 950kv, 10x7 prop = 6mins 37 secs flight time on full throttle, 1278gr static thrust (72g)

    I'm guessing the second one is best, due to more static thrust. and larger prop. But it will fly slower.

    Has anyone dabbled in flying wings of this size...60inch wingspan? I'm thinking I may be able to develop a camera gimbal for this with some thought. And it's a lot less work than the twin! 

    Also, if anyone has any experience with apm and the 3drs - does the below layout look okay...?



  • a little off topic.. But here are some pics of the wing I built, and will be using this weekend along with the twin if the weather holds. Hoping to do some more flights with the 433 3dr's. 



    May add a camera pod to the underneath of this.... we'll see

  • Sorry, Richard, but I don't understand why you're putting so much effort into this plane. The problem is that you have a foam fuselage and a heavy plane. The fuse is fragile. It will break very easily in a bad landing or even in a good landing on a rough field. The reinforcements will only make things worse, because you'll be adding a lot of weight, but no a lot of strength. The problem is that you can't really reinforce foam by sticking some rods into/onto it. The foam will just fail somewhere else around the glue joint. Nothing short of a frame will make a foam fuse strong enough.

    The point is that a foam fuses and heavy planes don't mix well. This comes from my own experience.

    Also, I would forget about landing gear, because it will limit you to golf courses and asphalt.

  • Considering getting a licence for MotorCalc - Is it worth the $39 CDN? Currently using the ecalc free web based software, but it doesn't save configurations.

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