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Tandem Wing

#1
Test Pilots Needed

I've created some plans for a tandem wing aircraft after seeing one on another forum. I'm not sure of its exact name but I've seen it called a Jidey J1-31 and Despratz Flash. Below are some pictures of a prototype model built with Ross foamboard. Anyone interested in trying to get this bird in the air?

bullywug-left.jpg bullywug-right.jpg
 

Keno

Well-known member
#3
Test Pilots Needed

I've created some plans for a tandem wing aircraft after seeing one on another forum. I'm not sure of its exact name but I've seen it called a Jidey J1-31 and Despratz Flash. Below are some pictures of a prototype model built with Ross foamboard. Anyone interested in trying to get this bird in the air?

View attachment 104632 View attachment 104633
Love to watch though, but it would be 2 day drive without sleep. nice work. Post pixs when you are ready to launch.
 
#5
Love to watch though, but it would be 2 day drive without sleep. nice work. Post pixs when you are ready to launch.
Actually, I haven't flown in a couple of years. I was hoping someone might want to build one and take a crack at getting it to fly. This is my first design. I have no idea what power it will need. What the CG is. Any takers?
 

Fluburtur

Cardboard Boy
#6
Well post plans of it and someone might try. I guess elevons on both wings would make it work nicely and I guess CG would be at the trailing edge of the front wing. As for power I think a 6" prop with 2000kv motor on 3s would work nice.
 
#7
Elevons on the front wing wouldn't provide much pitch authority, being so close to the center of gravity. This does mean that flaperons could be used instead, which would increase lift without any pitch-up or pitch-down tendancies (Assuming that's where the CG is).
 
#9
Well post plans of it and someone might try. I guess elevons on both wings would make it work nicely and I guess CG would be at the trailing edge of the front wing. As for power I think a 6" prop with 2000kv motor on 3s would work nice.
View attachment Print Jidey bullywug print1 v1.2.pdf
View attachment Print Jidey bullywug print2 v1.2.pdf

I don't have a build log but it goes together like a standard Flite Test aircraft. B-fold for the fuselage. Bezel cut to form the leading edges. It is sized for a standard power pod only cut shorter. The wing cut-outs in the fuse might need to be custom-fit. I don't have it in the current plans, but the ailerons/flaperons should be full length.
 

Hai-Lee

Old and Bold RC PILOT
#10
The Flight surface controls can be simple.
Set up one wing for elevon mixing. When sorted out all you need is a pair of "Y" Harnesses and the ability to mechanically reverse the servo/pushrod direction of travel on the second wing. (Just fit the output arm on the other side of the servo).
Rudder is as per usual.

The front wing Port servo is paired on the "Y" harness with the rear wing Starboard servo and the front wing Starboard servo is paired on a "Y" harness with the rear wing Port servo.

When done properly elevator "UP" causes the TE surfaces on the forward wing to drop and the TE surfaces on the rear wing to raise, (mechanically reversed).

A roll to port - Front port "UP" is paired to a rear starboard "Down" - front starboard "Down" is paired with a rear port "UP" Both port UP both starboard DOWN. A roll will ensue!

Use caution with control surface deflections and definitely use PLENTY of EXPO!!!!

Ensure that the ESC can supply supply sufficient current from its BEC to drive all of the servos at the same time, or everything will fail and crash!

With identical wings front and rear the approx CG should be half way between the two 25% cord points of the front and rear wings.

I hope this helps!
 
#12
I’ll take a crack at building it! Do you have some deminsions for me to verify my plans are correct? It is very similar looking to a Rutan “quickie”. I would build it elevators in the front and roll in the rear wings. I say don’t be scared and fly what you have!
 
#13
I’ll take a crack at building it! Do you have some deminsions for me to verify my plans are correct? It is very similar looking to a Rutan “quickie”. I would build it elevators in the front and roll in the rear wings. I say don’t be scared and fly what you have!
There's a scale next to the fuselage. 5 inch bar broken into 1 inch segments. Sorry I didn't add dimensions to it.
 
#14
I have seen info on this plane in one of Andy Lennox’s books on canard a/c. The actual a/c used the front wings much like a canard as elevators but with much less wing loading. They were at a higher angle of attack like a canard. The rear wings were used for the alerions. A later version actually drooped the alerions downward to enable the a/c to land slower approximately 20 mph. On tandem wing a/c both wings provide upward lift at the same time. So if you mix ailerons upward you would cause the a/c to be uncontrollable. The easiest thing to do is just use the rear wings for the ailerons.