I am thinking about putting an OS 91 FS on a King Kobra, and wondered if anybody else had done that, and if it fits, etc. Also, would I need a 3 balde prop so I would have enough ground clearance?

Thanks!!

a guy at my field runs a 61fx in his, flys great and pretty fast, but 12" prop is about it with standard wheels

You can use the 4 stroke and it will fit, but you will need to run a 12x10 prop or similar. This will work out great for you because you are looking for speed not trust with this plane.

Personaly I think this is one of the few planes that sounds "scale" with a 2 stroke, If I were you I would run a tower .75 and put the 4 stroke in something else...................ever heard a jet with a 4 stroke?

Hi! guy's, got a king kobra my self, the engine I'm planning on useing is a novarossi .50 ,witch should be a little liter than a O.S. 61fx or a .91fx ,I saw the spec. sheet on this engine & I figure that 2.2 H.P. @ 18.000 should be able to move the king kobra quiet w/ a tuned pipe. So tell me fellas what do you think?

I have had these with webra speed 91, os 61 and asp 61. My current one flys with a rossi 65 rear exhaust. Nice combo, great speed and unlimited verticle. With the rossi about 1.5 oz tailweight is required. The best was the os61 it was the vr rear exhaust short stroke motor. It really hauled and required no nose weight.

Flew mine with a Rossi 61 RE with pipe... great combo! And no nose weight required. Man, I wish I had that plane back... (dad forgot to secure the elevator clevis... arghhh!!)

Friend of mine had one with an Irvine .61 & pitts muffler. IIRC he was running a 12x7 AP prop. Great flyer, if a little heavy (for my taste).

It flew nicely until the rx battery broke loose and unplugged in flight... it went WOT straight into the dirt. Broke *everything* - even the wheels were split.

Here is THE setup for this plane: Super Tigre 90, MAC's muffled tuned pipe, and APC props. A friend of mine has two of these planes, both of them built during the Reagen administration (maybe even Carter). They both have 1500+ plus flights, and he burnt 20 gallons of fuel in them last year alone. Takes offs are in about the 15 foot range, and vertical is completely unlimited--turns into a small dot and you can't even hear it anymore. Look for VKerster on rcuniverse and ask him about the setup of these monster planes.