Just picked up one of the GP Gee Bee ARF from my local hobby shop. Got a really good deal on it. I got it because I've seen the Wings shows about the 30's racing events, i.e. "Speeders in the Sky".
You guys that have them, and I know there are a few. What engines are you using?
I'm considering several options, from a 1.50 four stroke, to a ST 2300, or a .90 diesel conversion.
I've already ordered the robart struts for it. And after reading the manual and the other threads that I researched I'll pay close attention to the CG. But most of the threads didn't discuss engines.
It will be a while before I get it flying, but would love to hear from those who have them.

Doug,
I have an OS 120 FS W/pump in mine. The instructions specifically cover this engine. The exhaust will exit out the bottom just where it needs to, all you'll need is an exhaust deflector. The 120 moves the plane around with authority, but it's no 3D machine. I've also go mine equipped with a Ram on board glow, cause the Gee Bee is one plane you don't want to have to Dead stick! This thing idles great and I've had no problems with this combo.

If I had to do it over, I'd be interested in trying an RCV 120SP so I could try turning a bigger prop. I don't know of anyone that's tried that engine. I may move my OS 120 onto a new GP Super Stearman and by the RCV for the Gee Bee.

No matter which engine you try, you'll find it takes off great, flys great, but landing is a strain on your nerves!

Steve

Thanks Steve!
The RCV 1.20 is an interesting option that I had not thought of. The larger prop would be a definite plus around the large cowl. Ducting and baffling the engine properly for cooling would need some thought and added work, but could be accomplished.

Any other Gee Bee flyers?

Doug,
I've never had to cool an RCV, so I'm not sure what kind of challenge it would present. I didn't follow the instructions for the Dummy engine exactly. Instead of cutting out a whole cylinder, I cut out the spaces between all of the Cylinders and covered it with screening. With the cowl mounted this allows for good ratio of inlet to exhaust area. This might also work for an RCV. One thought I had on the RCV....imagine the starting extension required to crank this thing!

Steve

Well Steve, the RCV engines are still an engine. I have one of there .90's and while I don't have it mounted in a model yet, on the test stand during breakin one will notice that they run a little hotter than any other four stroke engine. And since the cooling fins aren't in line with the airflow, one should make sure that enough air is baffled and ducted to keep them operating normally. Still doable in that big cowl. Have you ever visited there web site? It's worth a visit just to see how others have installed there RCV engines.

Hi!
I have flown my GB this summer and I use a MVVS 15cc (.91) twostroke engine swinging a 14x6 APC prop. I'm going to try a modified 15x4 APC this spring to see if it works even better than the 14x6.
Performance is rather good as it is capable of big loops and rolls and fly inverted without problem.
When I powered it with a 15cc twostroke it was low weight that was my goal. I had a SAITO 20cc (1.20) fourstroke on hand too, but the MVVS 15cc engine weighted almost 300g (10oz) less than the SAITO so I used it instead.
The GP GEE BEE now weights 5kg (around 11lbs).
Landings are a bit demanding at first, to say the least....as it has rather high wing loading but you learn after awhile how much you could slow it down before landing. But it takes some practice.

Regards!
Jan K
Sweden

Very nice Jan !!! You really went all out on the engine installation.
How did you do the hook up at the elevator for the pull-pull? I can't see in the photo, are you running dual cables?
Thanks !

I am running an OS 1.60 Gemini Fourstroke Twin and its perfect for power. I needed no weight for balance and the receiver/batter are in the factory locations. LIke was said above, takeoffs and flying are great, but woohoo landings you better watch out on. Its stall speed VERY low, but getting it slowed down is the trick. As the plane enters landing speed, things starts to get hairy. The elevator gets hyper sensitive. What is good or even soft in flight becomes touchy as heck once on final. If you bounce, go around, don't even think of trying to ride it out. Once on the ground get the idle as low as you can as quickly as you can. The plane is all but impossible to flip over with the engine off, but with it running it will flip at what seems like a crawl.

Thanks Jeff ! The Gemini 1.60 is a bit out of my budget but a worthy engine for the aircraft.
Are you using the Robo Struts?

Doug,
Forgot to mention the mistake I made with the Robostruts. I read somewhere that some thought they where to stiff, so I took about 1/4" off of each spring. On my second landing the plane landed and promptly flipped over. Required new wings as the struts were twisted right through them. Everyone at the field was shocked as it looked like I had it coming in right. After lots of talking and examination we determine that the struts had compressed and allowed the pants to literaly dig in (the dirt and grass stuck in the pants was the clue!). It probably came down harder than we thought.

Anyway, I have since put the full stock springs back in!

Steve

The OS 1.20 is perfect for that plane. I fly mine turning a 15x8 prop with authority. Well, it was flying until the sixth landing where the robostruts went right through the wing. The plane does great loops, inverted, and even nice knive edge. Like everyone says...landings are nerve wrecking. You have to come in hot, no matter what....forget about flaring. Keep the speed up, around 1/4 throttle on your final and lay it down straight and level on the struts, then cut throttle and up elevator. I wish I remembered to do that on my last landing. Oh, and forget about cross-wind landings too. Everyone makes fun of it, they even call it the flying watermelon....but it just looks great.

Murcielago,
Sounds like your struts did the same thing as mine. I wish I could build the wing myself because I would really like to strenghten up the area around the landing gear.

Mines fixed and ready to go, I just have to work up the nerve to fly it again!

Steve

Hi!
I didn't use the wooden linkage in the kit as this is too flexible for my taste and it didn't look nice to draw the linkage through the sides of fuselage, instead I used wires for both elevator and side rudder inside the fuselage where there is plenty of room.
The wires to the elevators go to a large bell crank made up of a aluminum arrow shaft tubing (Easton) and 3mm pianowire plus two 3mm allen head bolts..
I use this homemade system on all my models where ever I can ...much better than any other system available. It really gets the elevator surface stiff. You can't move even if you place your hand on it and push hard. In the second picture you can see one of the bell crank 3mm pianowire arms and how the wire is secured to it.
Also how the side rudder wire control is hooked up using small pieces of epoxylaminating plates CA glued into slots in the side rudder.
Large holes are lightening holes.....
Regards!
Jan K
Sweden

I didn't use the wood shafts either. I replace mine with carbon fiber to keep them stiff. Other than that I used the set up as detailed in the plans.

Steve