RE: What SPAD for a 25cc gas blower motor
shussey,
I followed the plans for the most part on the [link=http://www.spadtothebone.com/SPAD/ultraspadstick/]USS[/link]. I used the woodpecker/poly glue technique for adhering everything, instead of CA. My engine firewall, and landing gear block on the inside of fuse is made from 1/2" oak ply (not very light). I also used hardwood ( a scrap piece of cherry I had on hand) for the forward wing attachment block with (epoxied in) brass 1/4-20 inserts to screw the wing bolts into. I don't think using 2mil will gain you a lot, as far as weight reduction goes, so I have read in other threads. As I suggested before, Chris' 25cc Stick design would probably be the best match for the engine you have.
Forgot to mention, after the slow maiden flight of the 16.5 lbs. USS, I changed the prop to a 18X8 Zinger instead of the 18X6 MAS, that was on it, and tweaked with the needles which gave me about 700 more rpm. It flies a lot better now, (still trainer like) but rolls, loops, stall turns, and inverted flight can be done now with a lot more ease.
Later,
Omaha