mayday

I have a Sig Rascal electric airplane. Top wing, 400 size motor, 49" wingspan.

I cannot seem to control this on the ground. I've flown tail-draggers before, so i know they are squirrely, but nothing like this. At very slow speeds, I can keep it straight. But.. As soooon as I pick up any speed, it just spins around in a circle, one way or the other, usually dragging a wing in the process.

I've tried the following remedies:
1) Added washers inside the wheel pants so the wheels didn't rub. Thought maybe one wheel was slowing down and causing a turn.
2) Replaced the simple wire "dragger" in the back with a real wheel. This is connected to the rudder, so it turns with the rudder.

Still no dice. I can hand launch, but when I land it goes into the same spin.

What causes this? Balance, drag on one wheel, what?

Thanks,

Tall Paul

Main wheels too far forward of the c.g.

Sparhawk

Also check that the main wheels do not have toe-in. A little toe-out is acceptable for stability. How much throw is on that rudder????

Spar

crashingagain

A tail-skid makes a taildragger easier to handle than having a tailwheel. The drag helps to keep you pointed in the right direction

mayday

That makes sense about having a skid for extra drag. You'd think pulling back on the tail would keep things pointed straight.

The Wheels are pretty far ahead of the CG. I've attached a picture. The CG is right where the purple starts on the leading edge of the wing.

I don't notice any toe-in.

I love this plane though. It's an arf. Neat having a real balsa for a park flyer. It flies real nice, though not extremely powerful. I think a brushless would fit nicely under the hood and solve that problem though.

The battery compartment is right behind the wheels, so I'd have to move that somehow to push the wheels back.

BuzzBomber

My Feedback: (4)

Wait a minute. I was taught that toe-in is more desirable than toe-out, and given the logic behind it--made sense to me. the theory is that with toe-in, as an involuntary turn begins, the leading wheel axle will gain friction from being pointed away from the direction of travel and slow down, whereas the trailing wheel will be facing directly into the direction of travel, with minimal drag, and the differential friction will dampen any turning tendencies. It seems to work well on my planes[sm=confused.gif]. Am I wrong here?

Mikerjf

Toe in also gets the gear to stand up, toe out spreads it lower.

Mike

Matt Kirsch

My Feedback: (21)

Toe-in is desirable.

mayday,

What you are experiencing is called a GROUND LOOP, and it's quite common on taildraggers. It can be caused by many different factors, such as the wheels being too far forward, or too far back, too much toe-in, too much toe-out...

As a rule of thumb, the axle should line up with the leading edge of the wing when the plane is sitting horizontal, with the tail off the ground.

mayday

Thanks for the feedback.

I think there is a little too much friction in the wheels as well. I have washers between the wheel pants and wheels. they spin easily, but not completely free, i.e. if you spin it with your finger, it won't keep spinning. If these tail-draggers are this touchy, maybe this is the problem.

Mikerjf

What you are experiencing is called a GROUND LOOP, and it's quite common on taildraggers. It can be caused by many different factors, such as the wheels being too far forward, or too far back, too much toe-in, too much toe-out...

.............and not holding full up until the rudder's effective (too little elevator throw too, gotta plant that tail)

Mike

iflyprops

Yuppers, Gotta love those ground loops. sounds to me like like you are overcontrolling and/or are not quick enough with the inputs. If you have dual rates try turning it to low so you would be less likely to overcontol the plane, also I would keep the stick all the way back until you have rudder effectiveness.

I love the taildraggers! Real Men err, people, dont' need training wheels! (while attempting to keep a real cub on the runway...)