gas 4 strokes
 

has anyone looked at the new 40cc gas four strokes from OS and Saito for use with pattern planes?

tony

RE: gas 4 strokes
 

Cool. Now it's YS's turn [>:]

RE: gas 4 strokes
 

Surprised there isn't more interest in these engines.

Aren't they a drop in replacement for a ys setup??

Tony

RE: gas 4 strokes
 

Well the OS is supposed to mount on standoffs so I'd say it wouldn't be a "drop-in" replacement for any YS setup. Physically fitting within the confines of a modern F3A ship engine bay, then I'd say it could be shoehorned in.

Being petrol/gas and non-supercharged you're giving away power to weight right off the bat, but that aside if the F3A rules drift towards a take-off weight rather than an empty weight then I could see petrol 4-strokes becomming a viable option. I just hope OS is dipping their toes in the water and consider bringing out some proper sized 4-stroke twins for IMAC.

RE: gas 4 strokes
 

No, not close even! Weight is one major hurdle. Power output the other major hurdle. Size is reasonable and is not an issue fitting it into a current pattern model.

Weight is listed at a hair under 3 lbs (1300g) just for the engine. Add CDI and exhaust system weight and you're in the 3 1/2 lb area, maybe more

Power is not really close to the piped OS GT33 2 stroke or the YS175 4 stroke. It turns 19x8 prop in the mid 6's from one account. Total weight for the OS GT33 isless than3 lbs, (also true for the YS175), a huge difference.

Sound or noise, well, the piped GT33 is slightly quieter than the YS175 turning the same prop (at higher rpm). I have heard the OS40cc run but it's hard to compare sound levels. Noise is not objectionable and I'd bet if it was fitted with Hatori stuff, it would be even quieter. Bottom line, 4 stroke gasoline needs considerable development to become viable in pattern, while the GT33 is already there....