Torque rolls with a pusher

[Cautrell05]

Why is it that a pusher has more torque roll than a standard setup? My little 12' X-29 will roll inverted in about 10-12 feet right after the toss. I have tried throwing it with 1/4 throttle and going up but nothing seems to help. It has an EDP50 with a 3x2.
Nick

[Cautrell05]

Will one of the mods please move this to the electric jets forum please?
Thank you
Nick

[Cautrell05]

Anybody have any pointers for me? Please.
Nick

[Stefan lamers]

Hi nick
i guess one of the biggest factors is that during the launch there is no airflow past the vertical fin as there would be on a plane with a front propellor, also the small wingspan doesn't help.
you could try to put some side thrust in to counter the left roll (looking fwd from the rear tilt motor to the right).
hope this helps
greetings
stefan

[cbear]

Half Throttle , Throw The Plane Into The Wind With The
Rt Wing Tip About 5 Inches Lower Than The Left Side , Give It A
Good Throw And Get On The Sticks, Had The Same Condition On
My 3d Foamy Fa-18, Now I'm Used To It,after The Plane Builds Up
Speed Most Of The Roll Effect Goes Away,oyeah , Tall Grass
Helps Too . Good Luck

[Cautrell05]

Thanks guys. I changed the aileron linkage to get some more throw out of them. That should help a little at low speed. I have a stockcar to build this weekend but I will get back to the X next week.
Nick

[geoff.sim]

Half Throttle , Throw The Plane Into The Wind With The
Rt Wing Tip About 5 Inches Lower Than The Left Side , Give It A
Good Throw And Get On The Sticks,

I agree with cbear. My F-15 would torque-roll violently just after release until I realised that I only needed 1/2 power to launch. That and getting my hands back on the sticks asap. I lost it eventually to this problem. Complacency...
I must admit I didn't try dropping the RH wing tip on launch...

I bungee launch all my electric jets/planes now.

Geoff.

[Cautrell05]

so why does a pusher suffer from torque roll worse than a conventional plane?
Nick

[Guyffon]

I think stefan mentioned something about no airflow going past teh vertical stabs on launch unlike a tractor which has wind blowing over them on launch.

[William E Brown]

The main reason for the torque roll, is the slipstream swirl is straightened out by the fuselage and fin, in the tractor case, which doesn't happen with a pusher. This process also recovers some of the swirl energy, which is thrown away in the case of the pusher. This is one of the reasons why tractors have higher propeller efficiency than pushers, in spite of what some theoretical people predict.

When I was in the full scale airplane design business at Beech, the Brown rule was, "All pushers are 20 mph slower than predicted"