Got a quick question. Are guys not using gas engines strictly because of the weight? I am starting to look into what I want to build next fall/winter. After researching some specs on something like a Fantasy, I started wondering why I couldn't use a gas engine.

If I compare the wing area and weights of a Fantasy against something like my Sig Sukhoi I come up with the following.

Assuming 1100 sq. in. for the Fantasy, with a YS 1.40, I figure you come up with a finished weight of about 10 pounds. I figure the YS runs about 2 pounds, maybe a little more with the tuned pipe. Assuming all this I get a wing loading around 21 oz./sq. ft.

You can get a 40-50 cc gas motor now around 3 pounds. The DA 50cc is right at 3 pounds and the FPE 40cc is about 2.75 pounds. So add about a pound extra for the gas motor over the YS. This brings the total weight up around 11 pounds. Wing loading goes up to about 23 oz./sq. ft.

Compare this to my Sig Sukhoi, 1152 sq. in., 13.5 pounds, wing loading about 27 oz./sq. ft. The Sukhoi flies great at this wing loading and I have no complaints about it. It slows to a crawl and will accerlerate vertically no problem.

Will the performance of the Fantasy suffer from an extra pound of weight that much? What am I missing here?