OS .91 Vs Super Tigre .90

[Dgremlin]

I'm building a great Planes Gee Bee that will weigh in around 13 lbs or so. One of the engines the manual recommends is the OS .91. Just to save some bucks I'm thinking of putting in a Super Tigre .90. The Os is about .3 hp more but I'm wondering if either of these engines will be enough. Does anyone have any experience with these engines in a plane this size?

[Jack Horwitz]

I am running both the OS and Tiger 90 engines. They both run great but not in a 13 pound airplane! Any airplane over eight pounds will be a little to much if you want the plane to go vertical and stunt. I'm running the OS in a Great Planes
U-Can-Do. It comes in at 8 1/4 lb. It flys great but any more weight and you can forget about going vertical. If you want
OS, I would look at nothing less than a 1.40 to 1.60 for this plane. (I would go with the 1.60). Good luck!

[2walla]

I have both, the OS is not worth the extra money over the tigre.. I don't think either would be my choice for the plane your workin on.. You want a big prop to clear the cowl, and may need some nose weight. Maybe one of those really small gas motors? I would look at the 14 cc gasser TBM now. I think that they had them on sale since they bought out RCShowcase..

[planebender]

I don't know who does these HP ratings but I have run both for years and the Super Tiger is superior as far as power and you can also do a inexpensive hop-up if you choose. Remove and dispose of the stock ST carb and install a OS 7D carb. This is a monster and will greatly improve power beond belief and also increase idle quality. I have raced these engines and they are awesome. You will prolly have to do a little looking around for the 7D carb as they don't make them anymore. However they are still around for about 20 bucks used. They were about 100 new.

Hope this helps a little.

Planebender

[flyin4fun]

I have a GP GeeBee, I have a OS 120 four stroke (pumped) on it, It flys fantastic, great on takeoff, plenty of vertical, it is actually a "fast" aircraft, I used a 16X6 prop.....I also used a 15X8.they worked the same. it is just the 16X6 was a little larger to reach past the cowl. If you are talking about a 90 two stroke...it will be plenty of power (remember you are NOT going to do 3D)
As for a gasser (forget it) it will be toooooo nose heavy ....this aircraft has a very large fuselage , but not much wing area.....it is NOT a floater....so the "heavier" a motor you put on it will increase wing loading.
The GeeBee takes off great, flys fantastic, does a knife edge forever, BUT is a "bitch" to land...believe it or not..this "fat" fuselage does NOT slow down very well.

[Dgremlin]

Sounds good. I actually found a brand new ST .90 for $75.00 today! Couldn't pass that up so I guess that's what I'm going with.