goodinmw

Aloha Floppy,
RE: "I was thinking about mounting the Fuji 50 EI motor on, too, but someone warned me about gas engines producing more vibration than glow engines that may be a problem for a giant scale airplane. Any thoughts about that?"
Hmm- I don’t have any glow engines equivalent to a 50 gas- but if it's generating equivalent power, and it's single cylinder with a single oscillating piston (primary vibration source) I can't see where the vibration would be significantly different. possibly from different fuel volatility, pressures and required piston mass? In my experience biggest source of vibration is an unbalanced prop. In any case some other things to consider-
1) Gallon of glow fuel: $25 vs gallon of gas with oil mix: $5
2) Fuel system for gas does not require tank pressure and the location of the tank relative to the carb is not critical.
3) Fuel consumption- I have a 32oz tank in my Corsair, and I burn less than half the tank for 15 minutes of flying. I’ve gone 20-25 minutes but that gets real long. If your field is busy and occasionally gets fouled with stalled or crashed aircraft, it’s nice to have some reserve fuel to stay aloft. Corsair doesn’t dead stick real well, though I’ve done that a couple times as well.
4) Carb and engine are almost set it and forget it once you are past the break-in. I’ve not had any issues with the electronic timing- and the variability part is automatically controlled, nothing for you to adjust.
Not saying vibration is not an issue- you have to watch for chaffing of fuel lines and spark plug cables, elongation of holes in plastic servo and control surface horns/arms etc. Just I don’t know there’s a significant difference between glow and gas for equivalent power.
One other observation- looking at the RC aircraft market and trends- the giant scale craft are almost exclusively gas. the "pros" of gas seem to outweigh the cons.
Aloha Mark[sm=shades_smile.gif]