I'm getting ready to build some CF main gear for a few planes and was wondering what the optimum toe-in angle is. Anyone know? I was thinking three degrees on the right side and three degrees on the left side.

-Tom

That might be a bit much. When I raced r/c cars we never used more than 3 degrees total. However, on a plane with only two main wheels you might be alright with 3 on each wheel. I wouldn't go any more than that though until you test it with smaller amounts.

Someone that really knows (Full Scale guys) should answer this... I had a high wing tail dragger that would snap almost every time the tail was up and one wheel started to unload. We found that it had toe-in in the gear. As one wheel would unload, the other would try to track up under the fuse due to the toe in. A full scale guy told me to set the wheels to 0 deg toe or even 1 or 2 deg toe OUT. He said that this would cause the plane to try to stay on it's gear (one wheel down would track away from center, causing the other wheel to touch back down, keeping the plane under control). I checked mine, it was toed in, reset it closer to 0deg or even a touch of outward toe, and all was well from then on. Just my experience. But please check with the big guns before doing anything final.

Toe-OUT on a gear will almost GUARANTEE ground looping! Look at the facts... Refer to the picture below. The top 3 segments show a plane with TOE-IN. The bottom 3 show TOE-OUT.

In frames A and D the angles of the wheels are even in relation to the direction of travel and therefore have equal drag.

Now, let's compare frames B and E. In frame B the nose of the plane has shifted slightly to the right. This causes the Left wheel to toe-in even more, while the Right wheel "Straightens out" with the direction of movement. this creates more drag on the Left wheel and less on the Right, causing the plane to want to return to a straight track. Whereas, in frame E, with the wheels Toe-out, as the nose drifts to the right, more drag is placed on the Right wheel, while less is placed on the Left wheel causing the plane to want to go further to the right, and creating a ground loop.

Keep your taildragger wheels SLIGHTLY toe-in. NEVER toe out.

Remember, those full scale planes have a LOT more momentum than our little models have.

May all be true, but it worked for me, that's why I say ask those that "REALLY DO KNOW".

Just a minute.... look at B, is the arrow the path of movement? Then you are crabbing on landing due to cross wind.... your left wheel would touch first due to the low wing being into the wind, when it touches the ground, you flip. Right? That's what I see... and have had happen too!!!! IMHO

Ok, let's look at "B". Yes, the arrow is the direction of travel, and you're right, in this position you're crabbing into a cross wind... which in this case, would be coming from the RIGHT. Low wing into the wind = RIGHT wheel touches first.

I've found that the best handling planes THAT I HAVE OWNED, did best with no toe. Without exception, everyone was easier to take off and land with the wheels set straight ahead. With either toe in or out, they all wanted to wander down the run way.

John

DUH, THE PICTURE CAME TO ME LAST NIGHT, AND ALL I COULD SAY WAS OOPS. BUT I AGREE WITH JWN, ZERO TOE IS BEST ON A MODEL

Just enough to keep the gear from spreading. Anything with fixed gear will spread the mains if the wheels begin to track toed out.

Mike

Thanks for the explaination, MinnFlyer. I was wondering why toe in was suggested for everything (airplanes, cars). Now it all makes sense!

Herb

Oh yea, Don't get me wrong, The wheels in the pic are exaggerated for clarity. I'm just saying that if the wheels are going to toe one way or the other, you're better off having them toe-in than toe-out. I always set mine up so that they are ever so slightly toe-in, that way I know they're NOT toe-out.