Hello-

I am going to convert my Avistar 40 to a taildragger, but I have some questions since I have not done this before:

1. How far forward/back should I mount the main landing gear?
2. What type of wood should I use for the main landing gear's mounting block inside of the fuselage? I have 1/8" plywood. Would that work?

Thank you,

Bjfrankl

For the most part, the main gear should be just forward of the front of the wing, when looking straight down at it.

For the main gear, hardwood that is well reinforced along the sides of the fuselage with ply. So, make a pair of aircraft light ply plates that fit inside on both sides of the fuselage, fit it into place so that it reaches the top and extends front and rear about two or three inches, and epoxy that in place. Then fabricate a block for the gear to mount to that is about an inch square by the width of the inside of the fuselage and glue that in place with epoxy. I would add a triangle support on all sides that touch the fuselage and glue that in place with epoxy.

I only did this once and to the best of my knowledge, that was the way I did it. The hardwood piece may have been smaller, I don't recall, but it has to be solid in place.

For the tail wheel, I would fabricate a ply base that fits all the way to the rear below tail feathers, remove covering and glue it in place. The tail wheel assembly should attach to that. The ply base gives you something to screw into.

CGr.

I usually cut out a 1/4" thick plywood piece that will fit in the floor of the fuse right ahead of the former that holds the front of the wing and the next former if there is one. Then glue some triangle stock on the sides of the ply piece to take the vertical load. That will put the gear in the right spot just ahead of the leading edge Doesn't take a whole lot to hold the gear. Look at what they used where the tricycle gear mounted. (One little piece with a groove in it.) If you are using new gear, attach it with sheet metal screws that will pull out in a hard landing. Saves the belly of the plane. I wouldn't recommend using the wire gear that comes with ARF trainers. Too soft most of the time. There is a good fiberglass gear that springs back. Tetherite or someone makes it. Add a pushrod for the tailwheel or try a freewheeling tailwheel. High rate rudder should let it steer enough to taxi. Then go to low rates for takeoff. I am using a two-piece swept back set out of my junk box on my next one. Probably be tippy but that's OK. For some reason I bought a trainer the other day after flying nothing but 33% gassers for a while. It will be converted as I assemble it.

I did the same mod to my Avistar. Here's the pics - sorry for the small format.

Ichose to use a 2nd control rod from the rudder servo to control the tail wheel. A 1/4" piece of plywood LGbacking plate was insertedinside the fuse. Use tri-stock to reinforce the perimeter. In retrospect Iwould use 1/4x20 blind nuts with nylon bolts rather than the metal ones. Wasn't a problem as the plane died when used as a club trainer. The instructor on the buddy box wasn't quite fast enough to catch a screwup - my plane - my fault.

HTHto give you an idea.

http://www.rcuniverse.com/forum/Alph...2118831/tm.htm

Pictures and musings included!

Good project, you will enjoy the results.