Simple Cub uncontrolable on the ground

[rcwees]

so ive built a simple cub and i have had a sucessful hand launch when i was at a field but now im n the desert and cant land anywhere, so i made landing gear and it just spins out on the ground to the left everytime, ive tried slow takeoffs fast takeoffs and nothing. i have a c pack since i want to eventually go 3d, but any tips. i had a successfull ground takeoff but then the gear fell out of the plane and i couldnt find them. ever since the gear just breaks or it wont takeoff. and any tips for my next build or anything i need to know for my next scratch build?

 

[PsyBorg]

so ive built a simple cub and i have had a sucessful hand launch when i was at a field but now im n the desert and cant land anywhere, so i made landing gear and it just spins out on the ground to the left everytime, ive tried slow takeoffs fast takeoffs and nothing. i have a c pack since i want to eventually go 3d, but any tips. i had a successfull ground takeoff but then the gear fell out of the plane and i couldnt find them. ever since the gear just breaks or it wont takeoff. and any tips for my next build or anything i need to know for my next scratch build?

Its called ground looping when a plane spins out like that. The simple way to counter that is add rudder while you are taking off. It takes practice and time but a skill that is needed as many planes do this to some degree or other. which is why in a lot of RC videos you see people just yank on the throttle and get airborne as fast as possible instead of scale rolling take offs. You can also program some radios to set that rudder and a little elevator to kinda cheat that once you dial in how much of each is needed for your runways.

To be honest just keep at it and make a conscious effort to add rudder as you apply more power. I did several full pack roll to rotation runs without ever taking off to get used to doing that.

 

[cyclone3350]

The first thing U want to do is make sure the aircraft tracks straight. slowly add power to give it a little bit of speed and then power off. It should track straight coasting power off. I say power off, because tailwheelies have a tendency go turn left with power due to torque. Cubs are notorious for this. Adjust the tailwheel until it tracks straight. Then follow @PsyBorg advice.

 

[kilroy07]

I think what you are seeing is P-factor.
It's pretty common with tail draggers because (at take off) the nose is orientated high in the air vs a tricycle gear aircraft.
As psyborg said, punching the throttle helps because the tail will come right up and the extra air will give you rudder control.

Here's a good example, but basically the right side of the prop disk will pull the plane more than the left side (due to the angle of attack of the prop itself) before you have good authority on the rudder thus spinning the plane into a left turn.
http://ffden-2.phys.uaf.edu/webproj/211_fall_2016/Collin_Lasley/collin_lasley/PFactor.html
My storch was TERRIBLE when I tried slow "realistic" takeoffs...

If your plane is spinning either way (or to the right) and you have a normal prop setup, check that both wheels spin freely (with some weight on them) and they are aligned.

All prop planes need some right rudder on take off due to the slip stream effect, but p-factor is usually feels stronger (because it hits you right after you run up the engine for takeoff.)

 

[Byrdman]

Sometimes a little toe-in on the LG will help