Scratch Build With Guillow's Wood

[kittyfritters]

This proves you can build really light with the current Guillow's wood. The specifications for an A-6 are: maximum 30 square inches of wing area, all outlines 1/16" square wood, a six inch prop with absolutely flat, 1/32" blades... no camber...no sanding round on the edges, six inch motor stick, the ribs may be 1/16" X 1/32", and a minimum weight of 1.2 grams. The O.F.F.C. had an A-6 contest in October. I really wasn't going to enter but I decided, "What the Heck, it doesn't take that long to build one of these things."

I looked at ones that the other guys were trying to dial in for the contest and tried to analyze the features of the best flying models. So, I drew one up going for the maximum wing area, a swept wing for stability, dihedral tips, a lifting stab with twin rudders, and a 45 degree prop. When I tried to trim it out at El Cariso on the Saturday before the contest. Boy! Did I get it wrong!

A-6_1.JPG

The prop was so far out of balance that the model looked palsied when flying. The prop did not give enough thrust even with 3/32" rubber behind it. and the pitch trim was way too sensitive probably because of too much elevator area. The boom was way too weak to handle that much tail surface.

A-6_2.JPG

With other, paying, projects on my table I decided to do a quick and dirty fix before the contest rather than build another one. (What did I say about how long it takes to build one?) I made it a twin boom configuration, which solved the weak boom problem, and a 30 degree prop to get a better climb.

At the contest, I had trouble tying knots in the small rubber and had some motors unwind while I was winding. This is very frustrating, to say the least. I ended up flying it on a loop of 1/16" rubber. The low pitch prop gave a good climb, but used up the motor too fast. It did not have a good glide because of the excess elevator area and the best flights I got were about 45 seconds. You weren't even on the board with under 2 minutes. I might have gotten away with it if the elevator had been flat.

A-6_3.JPG

After the contest, I put a 4" North Pacific prop on it and it was and entirely different animal. In this configuration it's a fun sport model, but it's not an A-6. With a little rework I think that this twin boom configuration has some potential, so I will continue to work on it when I have some time.