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Help! Can't get Simple Cub off the ground

#1
I've built the SImple Cub as my first aircraft, and all the surfaces (rudder, elevator, ailerons) seem to be moving well ,as is the prop. However, it can't seem to taxi straight. It always seems to veer off (mostly to the left) and will flip/crash if I try to take off.

If I adjust rudder trim, I can get it to veer to the right, but it never seems to be able to taxi straight.

Any suggestions on what I can do wil be much appreciated. Let me know if I should post a video.

Thanks!
 

CappyAmeric

Well-known member
#2
It is most likely the natural "left turning tendency" in most propeller aircraft, where P-factor and motor torque need to be countered with right rudder in takeoff and climb. This is one of the reasons many FT firewalls have a slight right tilt and down tilt to them.

Posting video will help.
 
#3
I've built the SImple Cub as my first aircraft, and all the surfaces (rudder, elevator, ailerons) seem to be moving well ,as is the prop. However, it can't seem to taxi straight. It always seems to veer off (mostly to the left) and will flip/crash if I try to take off.

If I adjust rudder trim, I can get it to veer to the right, but it never seems to be able to taxi straight.

Any suggestions on what I can do wil be much appreciated. Let me know if I should post a video.

Thanks!
Check that your landing gear is straight.... That will also cause an issue
 

Merv

Legendary member
#5
If you want your plane to taxi straight, point the wheals inwards, (toe in).
Point both of them at a single point 5-10 feet in front of the plane.
If the plane is nosing over, bend the gear to move the wheels forward.
 
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#6
Have somebody give u a hand launch, probably a little easier than taking off the ground. And the simple cub can have some serious left turn tendencies, be prepared.
 

Hai-Lee

Old and Bold RC PILOT
#7
The swinging tendency is a part of the game. Normally increasing right thrust will assist but the real cause is the sudden slamming of the throttle to max as you start your taxi or take of run.

Learn to apply a little right rudder and then slowly open the throttle and allow the model to accelerate a bit slower.

When the model is running along the ground quite quickly you can then give a little up elevator momentarily and the plane will lift gently into the air. Gain height slowly whilst slowly pushin ght ehtrottle to max if not already at max and start flying as you see fit.

Just a little note: The simple cub lifts off easier and at a slower speed if you add a popsicle stick under the wing leading edge to increase the wing incidence angle a tad.

Have fun!
 
#8
The comments regarding right thrust are dead on. You can place a couple of small washers under the left side of the motor where the screw holds it to the firewall to provide that right thrust. Place one or two on the top screw as well for down thrust while you're at it. When you take off, don't jam the throttle forward. Ease it in while inputting right rudder at the same time. It takes some practice, so practice it. Do high speed taxi tests until you can keep it more or less on course. Or just hand launch it.