Ground loop
 

I have been flying trainers with some succes for about 6 months now and wanted a more durable/manuverable plane, so I put together a spad. My first try at flight did not go so well. I was on a lake that was smooth as glass with 2" of brand new snow on it. I would go to full power and just before lift off the plane would just do a turbo loop even with maximum opposite rudder. the plane does not have a tail wheel it just drags on the ground,but comes right up whith power applied. The rudder deflection looks about normal.My question is can I increase rudder travel? if so how much is too much? It doesnt seem right to have to give it that much rudder to keep it straight, no way I could hold it in a straight line in a runway situation, let alone a lake to take off wherever I want to. any suggestions? the pictures are of the plane without the landing gear on the tail area of the fuselage is cut at an angle to drag behind.

RE: Ground loop
 

Check motor off set and watch your throttle you might be trying to get off the ground to fast. Motor torqe will do this.

RE: Ground loop
 

I thought it might be motor offset it's one of those cut your own motor mounts. It appears to be straight and I used the template the came with the engine to drill the holes. Is there any way to check offset other than eyeballing it?

RE: Ground loop
 

it may need some right thrust some planes do some dont you might try putting washers under the left side of the motor mount if you can. also maybe just try accelerating slower if possible, just feed the power in smoothly what you have there is a tail dragger and they can sometimes be a little tricky to get off the ground. so if the thrust angle is off try washers but it may just need to be finessed off the ground

RE: Ground loop
 

could be the wheels are not aligned correctly.

Toe out is bad. excessive toe-in is bad. You want the dstance between center of the read to be barely less at front than at the rear of the wheels. Straight is OK, but not ideal.

From the CG at the wigh root at the bottom of the wing, draw a line downward 15 deg forward of vertical. The axle should be on that line. (this normaly has the front of the tire under the LE on a .40 size shoulder wing plane with 2 inch tires.) if the axle is directly under the leading edge... its usually not too far off for it to work. It is amazing how much difference there is in moving the axles back 1/4 inch on some airplanes though.

Don't slap the throtte full forward... advance it slowly.

On slick surfaces you need a tailwheel or something to help prevent the tail from whiping around. That coro fuselage on ice just dragging the back end may be a big part of your problem.

RE: Ground loop
 

Part of your problem is the very short tail moment. There's way too little distance between the wing trailing edge and the horizontal stab for the rudder to be very effective.

You didn't say which way it's turning when it ground loops; if it's to the left then add more right thrust, it may help some. But that plane will alway be a handful because of the tail moment.
Dennis-

RE: Ground loop
 

Any cross wind making it loop?

RE: Ground loop
 

NORTH RIVER , DID YOU CHK YOUR CG,AND SIDE BALANCE MAY BE THE PLANE IS HEAVER TO ONE SIDE?.I HAD A SIMILAR PROBLEM WITH MY CUB AND HAD TO ADD ALLOT OF LEFT AIRELON.IT TURN OUT THAT MY SPLIT ELEVATORS WEREN'T EQUAL

RE: Ground loop
 

That is a lot of weight if the wing is causing the looping. I would think more of the controls not being balanced than wing weight.

RE: Ground loop
 

THATS WHAT I MEAN, MAY BE SOME THINGS ADDING MORE TO ONE SIDE?

RE: Ground loop
 

Hey Senza,
First, let me welcome you to RCU, it's a terrrific place and there are a lot of nice people here.

I have a request though, would you please turn off your Cap Locks key? Reading all capital letters is difficult, and on the internet, all caps is considered SHOUTING! [:o]

(I still say, if it's not a lack of engine thrust, then it's simply the short tail moment.)

Thanks,
Dennis-

RE: Ground loop
 

DB has it; very short tail is the same as small rudder; I'm afraid you will need to double the barndoor rudder and vertical stab to take off the ground, especially without a tailwheel; on the other hand, most of my fellow club members fly a short little design called the Derelict SS for combat and they are hand launched with no sweat...JIM

RE: Ground loop
 

The short tail moment is definately a factor, but before doing anything else, I'd go with FHHuber's suggestion... Make sure that the wheels are toed IN slightly. This will drastically reduce the tendency to ground loop, because toeing the wheels in almost forces the plane to track straight..

If the wheels are even slightly toed OUT, even the best flier would have a VERY difficult time getting it to take off with out ground looping.

RE: Ground loop
 

don't forget the angle from CG to the wheels...

I had a neat little plane called a "Rookie" (not a widely distributed kit) that had a Terrible problem with ground looping. I covered a scrapof aileron stock and wedged the dural landing gear to move the wheels back... and the ground looping stopped completely. (most Cubs can be cured by tweaking the landing gear similarly...)