O.S. FS-30S + G.P. Combat Corsair

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Since combat planes have no landing gear (they are belly landed ) I would not install the engine inverted - you are unnecessarily exposing the cylinder and pushrod tubes to damage. Another thing to consider is that SOME engines are difficult to start while inverted.

What Ted said about not installing the engine inverted. It's true.

You picked a nice engine for your first four-stroke. I had the original version, the FS-20, and it was the sweetest four-stroke I have ever ran.

I just bought a new FS-30 myself, that's how much I liked that line of engines.

Ed Cregger

Bad idea....

Combat planes are for the most part, expendable... Good fourstrokes are not... The FS is a poor choice for this application. While it is a fine running engine, you'll need more oomph to be competitive, and it's more prone to suffer severe damage in the heat of battle...

Try a hot BB .25 2stroke instead...

DO NOT invert the engine at all costs... Makes for difficult starting and is gonna be rough on the engine during the belly landings.. Go with a side mount or even better on the Corsair, put it upright.

If you're NOT going to fly combat with this rig, use the FS, by all means, but I still would/nt mount it inverted...

Cheers,

Bill

Thx guys for your comments! Seems I'll wait for the plane to arrive, and check the possibility for the upright installation.

Since I will be flying in a more sport / semi scale manner, I am not so much worried about extra oomph.

In case I'll have to go with 2-stroke inverted, should I stick with O.S. 25, or have you any other idea. I am looking for more reliable, easy to start and set-up engine rather than other with 10-20% extra power.

Boris

If you have to go inverted, go with the two-stroke, unless you are willing to accept having to replace the cylinder head of a four-stroke at some point. The problem is that the exhaust header makes a wonderful lever with enough leverage to break the head casting where the exhaust pipe screws into the head. If you angle the exhaust pipe up out of harms way and keep an eye on tightness, you probably won't have a problem.

As far as starting goes, if you can manage to keep the fuel tank centerline at the carb spray bar's centerline, simply flip the model upside down for starting. You might want to make a special starting cradle to accomodate the model during starting. All flooding problems caused by siphoning and the attendant hydraulic lock-up then disappear. I really like the little four-strokes.

If you decide to go with the two-stroke, OS makes a nice engine, but so does Thunder Tiger, Magnum, Webra, etc. I would tend to go with the less expensive Thunder Tiger or Magnum. Though I have been known to fly Webras and OS engines too.

Let us know what you do and how you fare. Good luck.

Ed Cregger

Great advices Ed, thank you! Now I am almost positive I'll go with OS 25-FX.

OS, I say, because if you download pdf manual from GP (not so big file) you'll see engine and fuse cut-outs are actually made to perfectly fit 25-FX inverted. So, for a few $ more or less, who cares if I have to stay away from the sound & music of a 4-stroke (this time only).

Sure will keep you informed how the story (happy)ends.

Regards, Boris

My favorite 4 stroke installation is laterally. If looking at the fron

of the plane, either 9 or 7 o'clock. That way the plug is no collecting fuel and the top of the engine is not as exposed, and yo don't ruin the look of the cowl. Is that possible with the GPCC

-- blacksheepac

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Well, finally:

Motor built in: O.S. 25-FX, inverted.

First flight report in one word: AWESOME (except some difficultie during hand launch caused by left torque roll)

Regards, Bori

-- boris

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Thanks for the follow up report, Boris.

I had the same problem with a Fox .19BB powered Kombat King flying wing. Had to launch it at around half throttle or it would roll inverted on me right after release.

Anyway, good flying to you.

Ed Cregger

Boris, think of it being scale-like. The real Corsair was notorious for torque rolling on takeoff!

Morris