I'm pretty sure the FP 10 only had one case, marked FP under the exhaust stack.  The FSR series came before the FP and is close enough a person might think it's an FP.  The FSR probably isn't ABC/ABN, but otherwise should be pretty close to the FP in performance, might even be a little more aggressive.

This image borrowed from RCUniverse shows several OS 10's, and the .09.  The FP is in the upper right, the FSR is the lower right.  The lower left 10 is the Max series, which would be an earlier, less powerful engine, but still high quality.

The little OS .10"S" in the lower left corner is actually very much like a shrunken OS .35S!  A really nicely built 4-2 engine which is perfect for something like the Wee Duper Zilch.  It will also run a constant 2 cycle, but not with the power of the .10FP or .10FSR (and probably the .10LA).

I am considering building a Sterling ".15" size P-38 and using 2 of the .10S.

BIG Bear
RNMM/AMM

Bill,

Dump most of the kit and replace it with decent wood and 2 Norvel 074's would be really more then your prepared to experience when you fly it. I did that with my Sterling P-38 and used FP 10's and it is really 'Sporty when both engines are winding. But at least you don't have to worry about which engine quits first. The model is indifferent to it and just keeps flying along. But be aware that even lightened up the thing still has the glide ratio of a rock.

Dennis

Hi Dennis,

Thanks for the tips.  I am expecting the .10S running in a 4-2 might be about equivalent to the Norvel .074! LOL!!  Either way it will be simply a "fun" project.

Bill