Help! Issues Taking off

[Timmy]

Hi! My design team and I have built a plane. We did a test flight this weekend but it had trouble taking off, veering left and right uncontrollably on the runway. I thought I would ask on the forums since there are lots of experienced pilots here. Why do you think it won't track straight on the ground? I was trying to correct the whole time. Are the rules of thumb for landing gear design that I didn't follow? Do I need a bigger rudder? Another thing I thought about is that since we're using an under cambered airfoil, maybe its lifting the rear landing gear before the front so its wobbling around on the front landing gear as it gains speed?

Thanks in advance for any advice you guys have!

 

[LitterBug]

Try using more up trim on the elevator. It looks like the plane is trying to lift the rear wheels off the ground. At one point only the front wheel was on the ground.

Are you using differential thrust on the motors? Have you calibrated the ESCs so they engage at the same time? It seems like some of issues may be caused by differences in thrust between the motors.

Are your motors spinning the same direction or are they opposite of each other?

Can you spread the rear wheels farther apart?

 

[Merv]

...Why do you think it won't track straight on the ground?...

I'm guessing you don't have any toe in. You may have toe out, which will make the plane near impossible to steer.
Try bending the landing gear so both wheals are pointing at the same spot, 5-10 feet in front of the plane.

 

[Timmy]

Ya that seems to have been it! Added some toe in and now it tracks way better. Thanks Merv! I also did spread the wheel further apart. I will do another test and look into the elevator trim thing as the plane still hasn't been able to take off. Thank you everyone!

 

[tomlogan1]

Ae both wheels turning at the same "speed"? A sticky wheel can play havoc on takeoff & landings.