Could you guys educate me on what kind of OS 25 this is? Do you run it like a LA25 (prop,rpm,fuel)?

.25 FSR?

You may be on to something there!

Could you guys educate me on what kind of OS 25 this is? Do you run it like a LA25 (prop,rpm,fuel)?

     I think it's a 25SF. A lot more power than a 25LA in general. I wouldn't expect to be able to keep the airplane below the sound barrier with any commonly available props with a stock 25LA venturi. Maybe something like a really light 11-4 and a smaller venturi, but I doubt it would have the kind of maneuvering response you get with the 25LA.

   It could probably work nicely piped and I recall Darrell Harvin with a very similar setup back in the early 90's (maybe a 32 instead of a 25).

      Brett

     I think it's a 25SF. A lot more power than a 25LA in general. I wouldn't expect to be able to keep the airplane below the sound barrier with any commonly available props with a stock 25LA venturi. Maybe something like a really light 11-4 and a smaller venturi, but I doubt it would have the kind of maneuvering response you get with the 25LA.

   It could probably work nicely piped and I recall Darrell Harvin with a very similar setup back in the early 90's (maybe a 32 instead of a 25).

      Brett

Doesn't sound like this engine is going to do much for me then...

Doesn't sound like this engine is going to do much for me then...

  Need a bigger airplane than a Tomahawk, that's for sure. Fred's suggestion is a good one.

     Brett

I think the 25 SF cases were identified with "SF" as part of the casting.

Either one, FSR or SF, is a screamer.........

Is a 25FX in the same boat as this engine?

yea , FSR definately . used a clone ( Magnum 25 pro ) lots in a Nobler Sized thing .

9x6 or 10 x 6 worn to 9 1/2 , trike gear so the grass ronded the tips le nicely after
Id tried a few touch & Goes up the resivoir on the concrette in the wind .Impossable
to touch but was a bit of force in the wind .Tornado Props , the flexi 10 x 6 it bogged
a bit till it wore down .dunno if it was a black 9 x 6 or 9 x 4 for a blow , likely both ,
at times .



21/35 in it there , but mustve gone over 10 gallons thru the .25 in it . 52 span & 45 + Oz.
a quick wipe with a rag & petrol took a hour and a half , at one stage - when it'd got a bit
gooked up . Mine had a Fox bb 119/25 CL intake, so the needle was level with the outside of the fuel tank .
Got it rich down low & lean up the top of the circle . A bit gutless for it but kept you on your toes .
Magnums identical internally .
about OS 35 S performance .

used 55 ft. of .018 when it was blowing , but ive had that motor on 70 ft of 016 solids and it cruised along ok with a big sag in the lines ,
still drag itself over the top of the circle etc .

A Don Still Stuka would be ideal for it .