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[Andy M]

Having made a successful jackdaw/crow slope soarer many years ago, I decided to do another one, this time from depron and using a Wltoys F949S radio board. I still have my templates/plans from the first one so it went together pretty quick. The original was ailerons and elevator so I decided on this layout for my new version. The first one had no dihedral and a flat bottomed wing, this one would be undercambered and with dihedral (a bit too much as it turned out) it was also going to be powered this time. I had several ideas about where the motors would go, front of wings, rear of wings, in between its feet(fins)? Anyway, the model was almost finished by the time I thought seriously about the motor position. I decided to mount the motors tucked in close to the body under the wing, a simpe crossbar of 6mm depron 20mm wide through the fuselage and out the other side with the motors taped on looked like a good idea so I went for that. The 3mm black depron wing has bamboo leading edges ( from an old roller blind) and 3mm black depron ribs.
 I tried flying it this way and it wasnt great, ailerons seemed to work the wrong way round and it didnt climb or even fly level very easily. I decided that the leading edge dipped too low at the most forward point, so I unpeeled the front of the rib to allow wing to spring back up a bit. I also decided to try rudders instead using his feet/fins, this and the wing mod have vastly improved its flying, although the wing is still quite flexible, the dihedral angle changes in flight, I saw the wings move up till they were at 45 degrees to each other! And still flying. Anyway, I was not keen on a wingfold at height, so I added a section of a jumbo paperclip to the leading edge as a dihedral brace, this helps a bit but its still a bit flexible. Its still very much a work in progress but I am pretty happy with the way things have improved with just a couple of small modifications.
 I made his eyes from epoxy resin cast in ibuprofen tablet packet. The black gloss paint is still tacky, so I haven't fitted them yet.
 The aileron linkage is made from ice cream tub plastic, on a paperclip pivot. It adapted easily to work the rudders instead.
 I have called him Brandon, anyone know why?

[Subculture]

After Brandon Lee, killed whilst filming 'The Crow'.

[JimG]

Your aileron problems sound rather like adverse yaw caused by extra drag from the downgoing aileron. With the dihedral you have this yaw would convert into the opposite roll. The way round this would have been to use aileron differential with less downward movement than upwards. The basic radios you are using would need the differential set up by angling the horns on the aileron.
Jim

[Andy M]

Both of you are correct. I kind of expected the adverse yaw problem, as I had that with my canard model a while ago, changing to rudders on the crow cured the problem, I will maybe try rudder on the canard instead of ailerons. The canard was slightly underpowered as well, it may get upgraded to 8.5mm motor/gearbox instead of the 7mm setup it has just now.
The crow wing has had an extra rib added near the fuselage, as it was easy to flatten out the camber at this point, allowing the wings to flex up quite easily. I will test the modification tomorrow.

[Andy M]

Looks a bit better with his eyes glued on.

[Andy M]

Here is a video of Brandon flying, excuse the video, I filmed it while flying. You can notice the wings flexing in the video.
https://youtu.be/Gm4qGaP8RhM

[Andy M]

Brandon is no more, deciding to wedge himself firmly in a tree and resist all attempts to move him with sticks and stones.
 After the first hits, and broken bits, I pretty much resigned myself to just trying to get my rc back.
 Eventually it came down, but it is written off. I will keep any hardware bits I can re-use but most foam bits are wrecked. Ah well. He was actually a really good flying model, with pretty good handling characteristics for an unorthodox wing planform (standard fitment on crows though)
 I expected tip stalling to be a problem but never actually experienced any stalling. It did tend to turn tighter if you didnt steer out out of steeper turns but very controllable and easily straightened up.
 

[Andy M]

You may notice the carbon wing spars I added, which cured the wing flexing.
Anyway....... Mk 2 will be better. 😁

[ChrisF]

Video was pretty good considering you were doing the flying as well and not in a wide open space.

With the eyes on it looked like a gull!

Chris