i have about 4 flights on mine. And in the wind it just hangs like a kite at idle. i am using an OS 91 4 cycle. So far I have a problem with the fuel tank mounted too high. It floods the engine with a full tank of fuel all the time. i then have dead sticked it 3 times. The engine just quits when I idle it down in the air, but runs fine on the ground. It lands good but does nose over a few times after landing to a dead stop.
I did add about 4 oz at the firewall, but removed the 2 oz brass nut on the prop and it flies much more docile and doesn,t nose over a lot on the ground when taxxing.
So, I will now try to lower the tank somehow. If anyone has any ideas let me know how to do this!! i mounted it where it says in the booklet, at the hole in the firewall. It is tooo high , almost a quarter of an inch above the needle valve. Fuel just drains down into the carb with plane just sitting on the ground.

Sounds like your low end is too rich. I have a Magnum 52 that did the same thing. I had to turn it in a full turn to get a reliable idle. Could be the tank though. Good luck with it!

OK!!! I lowered the tank about 3/4 in. and VOILA!!! the problem was solved!!!
Heres the thing!! The manual photos of the engine and tank mounting (showing my engine, the OS 91 FS, show the tank mounted in the hole provided thru the firewall.
Guess what, thats tooooo high, causing the engine to flood while just siting there and also to run incorrect while flying.
Yes, I tried to lean out the mixture while idling and it helped, but it became tooo lean in the air, shutting down the engine.
I suggest that anyone mounting the engine inverted and installing the tank in the hole provided in the firewall NOT DO SO.
Lesson learned, DO NOT ALWAYS GO BY THE INSTRUCTIONS IN THE MANUAL
GREAT PLANES better think about this!!!

Good to know. I'll be starting mine some time this next week. How does it fly otherwise?

It flys rather docile. With this much wing area, it hangs like a kite with just a 5 mph wind and idling. Very slow landing, easy to control.
I was able to Dead Stick land it 3 times. No problem!! Elevator responds very good with factory throws. And one of the dead sticks I even landed opposit the wind direction. And it landed fine. I did have it nose over after it stopped on the runway. But that is due to the rough runway we have at the field, lots of ruts and stones!!
But yes it flys very controllable and sounds real neat with the 4 stroke 91.
Its a keeper for me.

Thanks for the info. I've got a magnum .91 to put on mine. Gotta finish my thunder bug first.[sm=cool.gif]

easy fix , just mount a remote fuel filler valve higher than the carb :P

A bear to land? That's hard to believe. This plane makes you look good landing its so slow. I only have about 3/4 oz. on the nose whihc is a weighted spinner. It has a 91 surpass whihc is sufficient. Need to check it over again real good for balance for next time. It is a greta plane and relaxing.

TVAN,
I too was concerned about tank placement initially, but decided Great Planes must know what they're doing. And until I read your post, I was prepared to install the tank per intructions. I have since lowered the tank almost an inch and feel a lot better about it. I'm about two weeks from finished. I'm surprised there aren't more reports of tank/engine ptoblems with the stock location. I wonder if the newer kits are still the same. Mine is about a year old.

I have 5 flights on mine with a magnum .91 and the tank in the stock location. No problems so far!!

I'm right on the verge of ordering this airplane. I'm thinking about putting an OS 91 surpass w/ pump in it, What do you guys think?. Also, are there any decals out there for this plane. I'd like to make it into a military version. Thanks [&o]

The .91 is more than enough power. I take off at 1/2 throttle!! I don't know about decals tho. It's a wonderful slow flier.