I have scaled a Don Still Stuka Stunt from the AT plans of 1952 to 71% which gives me a wing area of about 240 sq inches.  The engine that I would like to power it with is a MP jet .061.  I have both a plain bearing and ball bearing engines.  The MP Jet fits perfectly including the factory muffler and I understand they are quite powerful engines with the nod to the BB engine as being the most powerful.  I have read an earlier thread from years ago where Larry Renger mentioned not having any luck taming these for a stunt model.  My question is, has anyone else had any experience with them and if so what problems or success they have had.  Were the problem engines with the BB engines or the plain bearing model.
   I recognize that the one bolt venturi system could possibly give rise to seal leaks but that could be cured I am sure.  Talking with Larry once he mentioned possible air leaks around the shaft so I assume this was with the BB model.  This is the model that I would prefer to use as the fits seem very good on my BB engine and the PB engine has an excessively tight piston fit at the top of the stroke, so the liner needs at hone job to be usable.  Maybe a pressure fuel system would be a solution for the running problems.  I am open to suggestions and hope someone has been able to tame this otherwise nice little engine.
   The little Stuka is really a cute design and a pretty simple build with the non tapered wing.  The cockpit of course is another matter but not a real problem.  I have about 10 other .061's, but they all create installation problems, like the muffler equipped ones not protruding beyond the cowl and the high performance F1J engines are mostly rear exhaust and would need some serious de-tuning and or a serious scale up.
   Thanks in advance for any help as the MP Jet is the only real fit for this model.

Jim Rhoades

Thanks Rad,
   I was thinking along the same lines about using a crank case pressure tap.  How did you tap the case?  The back cover is plastic and some plastics are hard to glue anything to.  Did you tap the back cover or what?  As I recall the back cover bolts are tiny 2mm so I know of no pressure fittings anywhere near that small.  I wasn't aware of the spray bar configuration but plugging one hole might be helpful.  I was thinking that an APC 6x2 might be in the ball park for a prop.  Did you use the BB or plain bearing engine?

Thanks,
Jim

Bob,

Thanks for the info.  I haven't made any decisions on how what and if I this little project is to actually happen.  Out of curiosity, what size are the threads and orifice size are these pressure taps you have.
   I am still hoping some others chime in with their experiences and suggestions.
   I would like to build the full size model also with an FP or LA 21.  This early model Still Stuka is OTS legal but the later plan and Ambroid kit are not.  They are Classic legal but not OTS.  The nose moment on these is longer and some other design elements are similar but different.

Jim