tricycle gear placement ?.
 

are there a few basic and simple rules for locating tricycle landing gear on a scratch built plane ?.
thanks for replies.

The main gear needs to be as well behind the center of gravity and to give it good stability the nose gear are far forward as practical!

On a 50cc plane, I put the mains two inches behind the CG and the nose gear as far forward as possible, on the firewall. The static incidence is set at two degrees positive. Dan.



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Well, the main gear needs to be behind the CG but only so far as it will not stay on its tail if put there with an empty tank. The nose gear is usually close to the engine firewall.

The mount, for the gear unit, should be 10 % [of c/g} behind c/g . This will put 10% of total weight on the nose.
Putting some "caster in struts ,will help tracking, and put more weight on nose

Yep, if it's too far back it makes the rotation at liftoff more harsh. And when you roll on during landings if it's too far back it can force the nose down more harshly.

There's no real set number. But the 10% back sounds like a darn fine number. If it's something close to that you should be fine. But it's also nice if the model doesn't sit down on the tail if something tips it up. So some slight fudging might be needed. With wire just bend it. If you use a sheet metal gear or a similar style of made up gear you can alter the wheel positions by shimming the front or back of the sheet metal mount on the fuselage.

A very good book for scratch builders and designers everything from basics to advanced. Its an older book but the info is still valid today. R/C Model Aircraft Design by Andy Lennon on line downloads as a PDF file. You can scroll through the whole book online at http://www.scribd.com/doc/55837270/R...-Design#scribd Chapter 25 page 125 shows basic proportions for both trike and taildragger gear.