dolanosa

Just wanted to know if anyone out there has made a plane with split aileron/airbrake like the B2. I'm building a tailless plane. I was thinking about the B-2 design and how the outboard ailerons can be used as rudders by increasing the drag on that side of the wing. To keep the plane stable, the plane will use a gyro for the elevator and the drag rudders.

Has anyone done this before, especially the programming side for a JR 8103? Thanks.

Ed_Moorman

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I thought about that a while back, but never implemented it. I had an 8103 at the time. Now it's my reserve and the 9303 is my main man.

I had it using a control horn on top and bottom and 2 pushrods going to a belcrank which was connected to one of two rudder servos. With this set-up you could use a Y-connector and not do any programming, but using 2 channels and mixing might be easier.

I have had to mix for 3 flap segments to get them together. I Y'ed the center flap and 1 outboard flap, then mixed the other flap and adjusted it separately to get it to match the other outboard flap.

What you could probably do for testing is make some removable fins, balsa or clear plastic, to fly the plane and test the rudders. The fins would keep it going straight and you could play with the split rudders up in the air. I woiuld learn to fly the plane first and get it balanced and trimmed out so it flew well. I would try spins and spin recovery, both upright and inverted.

Then I would start in on rudder testing. Once you got them working, you could phase in the gyro. If it seems to work, I would start trimming down the fins and checking the performance. I can always tell when a plane doesn't have enough vertical tail area because it goes into a turn nose high like it has adverse yaw. WW II fighters built true scale are notorious for this.

You'll have to play with the gyro settings and I'm not sure which type of gyro to use. The heli guys might be of some help here.

As for the airplane design, I would use a tractor configuration instead of a pusher for the first tests. If you get into an uncontrolled situation, a tractor design will have prop blast over the controls which will help you recover, whereas a pusher relies on airspeed.

I would also consider using Bill Evans' ESA 40 airfoil. This is an excellent flying, reflex airfoil. Dynamic Balsa can cut you wing cores. They have Pole Star cores available and can make anything else you want. What I mean is, start with a proven design for testing so you know it'll fly. Then if something goes weird, it is the rudders or lack of vertical area.

dolanosa

Ed,

Thanks for the reply. I completely agree with you about putting in a fin for testing and taking it off when I know the split rudders work. I designed and made a large coroplast flying wing for the 2004 SPADFest (definitely with help) but it was more of just a very sport scale using elevons and sporting a vertical fin. A new design I have in mind would be a pure flying wing without vertical surfaces.


I'm sorry but I cannot seem to visualize your method with the bellcrank and the two rudder servos. It sounds good though and easy enough to set up mechanically. I was thinking about having two servos for each split and Y-connecting them. This will go to the rudder channel. The second set will then be connected to another channel.

The mixing would be tricky. Since the rudders would normally be closed, a control input would "close" one set more, stalling the servos on one side. I would have to program one input to be 0 movement on one side and vice versa. I think the 8103 can handle this, right?

I'm getting some scrap coro tonight and test it out but I will definitely let you know by next week if get something going.

Thanks again for your help.

rotccapt

i have thought of this before because some day i will build a largish b2. i love that plane. so here is my 2 cents. the b-2 uses elevons to control roll and pitch and the drag rudders to control yaw. so here is what i would do i would have one servo per rudder you would either have control horns on the outside or the inside either would work outside is easier though. you would then run these into a heading hold gyro and one servo into the rudder channel and the other into another channel you would then mix the two together and program in zero travel for one direction and on the other channel zero travel for the other direction so that when you move the rudder stick only one servo actuates at a time.

if you have ever flown a flying wing without verticals they like to get a wobble that looks like fishtailing i think that the heading hold gyro would help to eliminate this fishtailing

now i have never tested this theory in flight but it does work when playing with servos