Help! Can't get Simple Cub off the ground

[Chanak]

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]

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.

 

[Matthewdupreez]

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

 

[Chanak]

Thanks for your help, CappyAmeric and Matthewdupreez. Will try these suggestions.

 

[Merv]

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.

 

[Flightspeed]

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]

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!

 

[earthsciteach]

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.

 

[chrisvdv]

I had the same problem with the Cub I built. Solution: fitted a cheap steerable tail wheel.

 

[sprzout]

I had the same problem with the Cub I built. Solution: fitted a cheap steerable tail wheel.

I did something similar, only I used a barbecue skewer with a little bit of bias tape wrapped around the end, as a tail skid. Lots of different solutions.

 

[chrisvdv]

As long as it is steerable and not fixed.

 

[jaketeater]

...
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.

Do you have a picture of a plane with a popsicle stick installed that way? I'm new and want to make sure I get it right.

I'm having similar issues (with my very first plane - a simple cub). I can get it to fly, but wouldn't mind slowing it down a little, at least while I learn. And I am also having takeoff (from the landing gear) issues as well. I did point the wheels to about 8 ft in front of the plane, and will be testing that out shortly.

Thanks to all for the helpful info in this thread.

 

[Piotrsko]

Popsicle stick goes under front of wing on top of fuselage. placement isn't critical but straight to the fuselage sides is. Popsicle stick because they are consistant, available, standard.

Aircraft running on ground is known as taxiing. Start slow and incrementally go faster until it is flying.

 

[jaketeater]

Popsicle stick goes under front of wing on top of fuselage. placement isn't critical but straight to the fuselage sides is. Popsicle stick because they are consistant, available, standard.

Ahhh! I get it now.

I was about to hot glue Popsicle sticks on like flaps.

So I just put it between the wing and fuselage, raising up the leading edge by about 1/16" - that makes a lot more sense.

Thanks!