Who has flown a Roo setup with elevons only? This means no rudders or elevator. What did you think of flight performance?
Thanx!
Myles

I have not, but by pure definition the roo does have elevators.

What do you think elev is in elevons

I watched a guy from Mexico fly his elevon only Roo and it looked like it flew just fine.

Kangaroo does not have a tail and therefore cannot be flow with "Elevator". A delta wing platform uses Elevons which is a combination mix via the radio so the aileron works as elevator fuction as well. You dont need rudders on a roo, for that matter they are barely enough as supplied to be effective but the AMA requires rudders on all turbine powered aircraft, thus the reason we all have them.

Todd

lov2flyrc and grbaker,
Thanks for the info guys!I'm here in Canada and I don't tbelieve we have to have rudders so I think I'll skip that part and move on! Roo should be ready in about a week!
Thunder AI, what lov2flyrc said about elevons is true my friend!
Myles

A delta wing can indeed have separate ailerons and elevators. Nothing says they must be mixed - you can have outboard ailerons and inboard elevators, unmixed.

AJC

Andrew, indeed you are correct.
Both Enforcers I have, have both elevators towards the center with ailerons on the outboard wing. I'm doing my Roo strictly with elevons only. How did you do your Reaper?
Myles

straight ailerons on the wing, with the elevators on the canards. No mix needed.

AJC

ok, here is my question, on the composite Roo, the elevons are split on each wing for redundancy, can you use the inboard halves for elevators and the outboard for ailerons so you don't need mixing? or are they not powerful enough individually?

What I did on myRoo was join the split split elevon back together
I suppose using the inboard for elevator and the outboard for alierons would work..............??
Myles

The reason most split the elevon is for redundancy. With just two elevons, if one of the servos fails or linkage comes off you will have no control and crash.

By splitting them you could have both move together as elevons or possibly separate the elevator and aileron functions. Either way if one surface fails you would loose some control, but now have a good chance of getting the plane back in one piece. When you have $5K+ invested the cost of two more servos is cheap insurance.

Joe

I'm not disputing that at all, and I agree with redundancy, just curious if you could use them seperately.

Now, with the elevons split, you should be able to use a slightly smaller torque servo I would think?

In my first Roo I had 8411's, (155oz) on the elevons and never a problem, I actually originally had 8231's on them, (90oz) and I didn't have a problem, but I upgraded. So on the new Roo, with the split elevons, 8231's should be plenty of torque right?

With split elevons you would then have 180 oz-in available to do the same job that that was being handled by 155 oz-in. With everything else equal, the amount of servo load required is directly proportional to the area of the control surface.

Joe

No Rudders, no problem.....but splitting the elevons into independent elevators and ailerons will be a problem on the Roo.
Lots of deltas like the Eurofighter and Rafale do it, but you need canards and washout in the wing.

On our Roos, if you split off the ailerons with no mix, you definitely will not have enough pitch authority for takeoff and landing. It needs all it can get as it is currently designed. They take-off and fly nose heavy due to fuel in front of the C.G. Additionally, by cranking in all that up elevator with neutral ailerons in the landing flare, you are asking for a snap, since the AOA of the inboard wing will be significantly less than the outboard, the opposite of washout.

Redundancy is great, but rarely needed. My buddy has over 100 flights on his foam wing Roo-I with one 8411, and I have over 100 flights on my HS, also with one 8411/side with absolutely zero problems. Just finishing up a new foam wing Roo for 3-D stuff and it also will have one 8411/side.

Just Y the elevons together. 8411's are fine but overkill with 2/side. 70oz servos would be enough, IMO. I flew my first HS with single 4131 and then an 8231/side for over 100 flights with no problems.

Tom

While it is possible to have a Delta configuration with a "Elevator", this is not a true delta configuration and usually with this type of setup, pitch authority is much less authoritive than what elevon control would provide.
I am no aerodynamics expert by any means but.... Setting the roo up with seperate (outboard) elevators/ailerons is inducing instability into a fairly stable platform. If you had a control surface at the center of the delta for pitch control you might get good response but I would not attempt using the wing surfaces as seperate controls. And for that matter, why would you want too?
BTW.....almost 300 flights on my roo with single 8411's per elevon without a hitch. The million dollar question........ Can you actually land a roo with one failed elevon servo ( when using 4 servo setup) ??
Todd