Friday 3 April 2015

1.2m Acrobat

I was keen to try some aerobatics with powered planes but The Red was not quite up to the task. Too much of a glider and not enough rudder. So this is what I came up with.

It has a 1.2m x 180mm 12% chord Armin wing and a 700mm fuselage both made from 6mm depron covered with 75 micron document laminating film. That is the thicker laminate and it added lots of strength.

I also wanted to try a design with the tail as part of the fuselage, and test a full flying elevator setup. Both are working very well so far.

Fuselage construction started with the side and bottom panels in uncovered depron

The sides were glued on top of the bottom panel, which defines the width of the front area.

The tail halves were glued together giving the taper curve, then top and bottom panels added.

The fuselage was then covered with 75 micron laminate. 
This added a great amount of strength, especially to the narrow tail area. 

The 2826/10 1400kV motor is mounted to 5mm plywood with ventilation holes drilled out. Initially I built in some down thrust but I am still testing to find the right amount. Plastic washers can be added or removed to vary the angle.

The most radical feature of this design is the flying elevator. The whole horizontal stabiliser pivots on a 3mm carbon fibre rod which also acts as the spar. The rod passes through a brass tube glued into the tail. The inner diameter of the brass tube must be just bigger than the CF rod to give free movement but minimal wiggle. To hold the brass tube firmly there are 25mm discs of foam sandwiched between ID card plastic on either side.


Overview and build video

Field and slope flights

Armin wing span - 1.2m (47") 
Airfoil chord - 190mm (7") including 45mm (1.5") ailerons
Airfoil thickness - 23mm (12%) using 9mm formers 
Spar - Skyshark P4X 7.5mm x 850mm, 57mm back from LE
Fuselage Length - 700mm (27.5")
Flying weight (2200mAh LiPo) - 770g
Full span Ailerons / Flaperons
Full flying Elevator
Large Rudder
TGY 9018MG servos x 4 
Motor - Turnigy 2826/10 1400kV with 8x4 prop
ESC - Plush 40A



  1. Hi Andrew, very nice plane! I'm building a thing similar to the Red, but I 'm a bit cocerned about the propeller: doesn't it hit the ground on every landing?

    1. Yes it does but it's not a problem. I have never damaged a prop on landing. Set the motor brake on the ESC so it's not spinning when you land and it will be OK.

    2. Well, probably the props I' m using are too weak (Hk) but i managed to broke 3 of them out of 4 flight sessions (always bent backwards) . They're also significantly undersized, I'm using some spare 5" coming from a 250 quadcopter...
      What props do you usually mount?

      Btw, my Depron plane built using your techniques proved to be a very enjoyable and sturdy flyer, with or without motor (even if the pilot is still struggling to learn the very basics:-) )

    3. This is what I use

    4. Thank you for your very quick answer! I'm waiting for some props, meanwhile here's the maiden flight with the quadcopter propeller (quite a windy day and a small field):
      The pilot (me) has very limited skills, and it shows, but I'm hooked!

  2. Hi Andrew thank You for everything my videos i have rising problem please help me im using emax 20a esc and emax xa2212/1400kv with 8x6 plastic propeller my first plane thank You again

    1. Great first attempt Sami. It will fly when you get it balanced. I have left some suggestions on your video.

  3. it's me again :) hello Mr. Andrew today test with carbon tube wings.

    my impression, the plane tend to rise. if I get the centre of gravity forward,I'm having a problem, sudden it does not rise but very stable. it's quite fun. thanks for the help. best regards

    1. Excellent Sami, looks like you have it flying well.

    2. thanks to you, it was a successful flight

  4. Hi, I 'm building this plane and I would like to know where the CG , using your wings design depron Thanks

    1. Hello. My CG is 55mm back from the leading edge. Good luck with your build.

    2. make this wingspan less than 1.2m, could I?
      folding the fuselage, but we can put the magnet to make it to be connected again? and then..
      is it good idea and not some mistakes to use DIY 3S 18650 as this rc aircraft power.. ? thnks..bro(Y)

  5. Hello sir, I am building the same plane and in every flight attempt it was failed. I used emax bl 2826/06 850 kv , ZIPPY Flightmax 4000mAh 4S1P 20C and APC 13X6.5E propeller. Could you give me any advice to solve the problem by seeing the video in this link.

  6. I also uploaded the video on Youtube thank you sir.

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  8. Hi Andrew,
    where is the plane of the wing.

    1. There is no plan for the wing. Follow my depron wing build or Ed's Armin wing build Dimensions are in the post above.

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