Best small engine combo

[Shorts,David]

Hi all, not sure if this horse has been beat to death. I just got plans for a plane that is supposed to come out about 20 oz. Original engine was Forster .29, but also Arden .19, Ohlsson .23.
So, suppose I want the PA .75 equivalent around a 20? Anyone tried a rear exhaust .15 (ops?) on a pipe for stunt, or only for speed? Fp .20 is a clear contender, but is there better options for glow? If I go electric I'll just use my combo from my akromaster...maybe.  thanks

[Brett Buck]

Hi all, not sure if this horse has been beat to death. I just got plans for a plane that is supposed to come out about 20 oz. Original engine was Forster .29, but also Arden .19, Ohlsson .23.
So, suppose I want the PA .75 equivalent around a 20? Anyone tried a rear exhaust .15 (ops?) on a pipe for stunt, or only for speed? Fp .20 is a clear contender, but is there better options for glow? If I go electric I'll just use my combo from my akromaster...maybe.  thanks

    I think a 20FP is likely to be the F1 rocket engine of small airplanes rather than the PA75. Holding down the speed with an available prop will be difficult/impossible.

   What size airplane are we talking about?

    Brett

[John Park]

I used to fly full-fuselage flapped stunters (such as the KeilKrsft 'Spectre', but mainly O/D) with a wing area of 350 to 360 sq. in., weighing 22-24 oz., on 52 ft. lines with an OS-Max .15-III and a Fuji .15-III.  I'd say an OS .15LA would meet your requirements more than adequately.

[C.T. Schaefer]

Here is some current info.  I have an Umland Shark .15 16oz. . Fox .15x with smaller venturi and less compression, 8x5 prop.  58 x .012 lines. Very capable for a nice pattern. Joe Gilbert judged me at Brodak profile class.  Another smallish one.  Brodak Peacemaker. 24 oz..  Brodak .25. APC 9x4 and the same 58 lines. Does a nice pattern. Hope this will be useful info for you.  TS
  PS   An LA .15 might be good for a 20 oz. ship

[Brett Buck]

Rule of thumb is that if it flies well with an Arden 19 or Ohlsson 23 - think more like a Enya 09, or for a power boost, a Medallion 09. Any of the baffle-piston 15s (with the one exception, which the foundational principles of The Hurl prohibit me recommending for this application) are generally plenty and will give you a great power boost compared to the original.

    The problem with these sorts of models is that for an Arden 19 or similar, they have to be tiny for decent performance, but they are build very heavily to take the vibration. So something like a Tee Dee 049 would get you similar power, but the rest fo the model is so heavily built that its a brick anyway.  It might be the right size for a 1/2A, but way too heavy. The SIG Akromaster is a good example, its' smaller than the best 1/2A stunt planes but 50-100% heavier.

    Brett