FM-1 Wildcat
Hi Thayer,
I built a Dumas Wildcat last year. Despite its hefty weight, and thick semi-symetrical airfoil, it flies surprisingly well.
This new one is my attempt to improve the plane. The formers from the leading edge back are the Dumas shape, but with fewer stringers. The nose on the Dumas is actually shorter and fatter than my 3-view shows! (You'd figure that if you're gonna be wrong, be too long and thin in the nose.) I changed mine to match the drawing.
The wing has the same outline, but about 1/2 the thickness. It's built like the George Bredehoft Caudron with a full depth spar and ribs made from 2 pieces of 1/16 square. Very strong and solid despite the relatively thin airfoil. I think that this is definitely the way to build a wing.
ALSO, I attached the wings using a suggestion from "Mad-Doug" Wilkey. Each wing has an extra 3/32 soft balsa rib at the root. This rib is shaped, then butt-joined to a medium weight 1/16 balsa area on the fuse. The idea is to let the wing break away if (when) I fly it into a basketball net. I tried it out by wacking one wing.
It works just fine.
The stab is about 5% bigger than the Dumas, and the fin/rudder is ~10% smaller to mitigate some of the spiraling tendency I had on the Dumas plane. I enlarged the stab to help compensate for the pitching moment coefficient differences with a flat-bottomed (more camber vs. semi-symetrical) wing.
I don't remember the exact weight, but it came out 20+ percent lighter than the Dumas. I think it's 20 gm..
I'm using the great MPC 6" prop. I've only done some quick flight tests with an indoor motor. So far it looks very good.
Tissue is colored with gray and white chalk on the back. It's pretty easy to get a nice cammo pattern with the chalk. The tricky part is matching the gray/white color break on separate pieces of tissue. Krylon clear, of course.
I covered the fuse with wet tissue, and you can see that I goofed up. When covering wet, the tissue stretches alot. In this case it meant that the gray color carries too far back onto the fin by about 1/2 inch (12mm). Next time I'll know to make the cammo pattern a litle too small, thus compensating for the stretch.
Markings are from dyed bond paper. The antenna mast is mounted on a small piece of tan 2 for crash resistance; it flexes. The antenna wire is lycra thread. Pilot (in genuine khakis) is 1/24 size from Small Scale. Knight & Pridham adjustable thrust bearing. The sun was at a low angle, so the plane looks a little more yellow than it really is. Also, it's not flying. Photo-magic.
I won my only kanone with the Dumas Wildcat. Granted, my glorious victory involved Tom Nallen II torquing in, Rich Zapf and Jack Kacian breaking their rubber, and a bunch of better fliers - with better planes - having every problem imaginable. Would you believe a swarm of locusts,...?
Anyway, this plane looks to be a definite flying improvement. By mid-winter it will probably have the extensively patched, "lived-in" (more like "sat-on") look of my Dumas Wildcat.
CP
Copyright 1998, Thayer Syme. All rights reserved