Engines for small Sterling kits?

[frank mccune]

     Hello All:

     I would like to have a few suggestions for an engine that would be good for airplanes the size of the Sterling Yak 9, F 51 Mustang, Ringmaster etc.

      What I am interested in finding are engines that are:

      Easy to start and adjust.

      Weigh no more than seven oz.

      Engines that have sufficient power for the full pattern.

      These engines must be equipped with a muffler.

       The only thing that I have in my junk drawer that fits this description is a Fox .19 1956 era, Brodak .25 and a Fox .35.  By the the time these engines are equipped wit a muffler, the plane is quite nose heavy.

        Perhaps the answer lies in a hot .15 size engine that is light.  I have a Magnum .15 that turns.an 8-4 at over 18,000 rpm.  Will this work for this task?

       Suggestions/Comments

       Tia,

       Frank McCune

     

[James Holford]

.25LA altho Im not sure on its weight.

Sent from my SM-G965U using Tapatalk

[Brett Buck]

       The only thing that I have in my junk drawer that fits this description is a Fox .19 1956 era, Brodak .25 and a Fox .35.  By the the time these engines are equipped wit a muffler, the plane is quite nose heavy.
   

  None of those engines will meet your criteria, particularly the weight. For a Ringmaster (regular S1, not a Ringmaster Junior), the engine of choice is a *stock* 15FP. Potential second choices are a Veco 19BB or a 20FP, although controlling the speed will be very difficult with either of those. The engine you have that will provide satisfactory performance is the Brodak 25 - not as effective as the Veco 19, but adequate.

    None of these will be anywhere near 7 ounces with a muffler, but a better engine and tail weight is FAR BETTER than a vintage engine and no tail weight. And, vintage engines generally don't have and cannot use an effective muffler, and only have mickey-mouse arrangements to mount them.

    If you are talking about the "Junior" models originally powered by 15s back in the 50's, then the Fox is plenty enough, and the others are far too much. My first "big" airplane was a Ringmaster Jr. with an ST G20/23, it was a complete bomb that went about 90 mph and routinely shed parts. And a 20FP is stronger than a G20/23. If I was doing it again, I would build my Ringmaster Junior using a Hornet .09, or something like that.

     Brett

[Gary Dowler]

Kits of that size, you can’t beat a OS 20FP!  Fit it with a 9-4 APC prop, lean it out, then open the NV just until your ear detects a slight rpm drop, and go.
All the power of a Fox 35, with more consistent runs, and will use only 2oz of fuel to do what the Fox would need almost 4oz to do. Hence you can save weight with a smaller tank.

Gary

[mccoy40]

maybe the K&B 20 sportster?

or the new Mecoa K&B 18 possibly?

ASP also has engines in the smaller range as well

[John Park]

A .25FP-S would have vastly more power than you'd need - my early version (steel, not ABC) weighs 8.1 oz. complete with the standard silencer.

[Phil Spillman]

Hi Frank, I am flying my Sterling P-51 with an OS FP.20 iron piston and sleeve using an old paddle blade Top Flite 9 X 5 prop on 58" lines of .015 diameter. Flies great and will perform the entire PA routine! Not intended for competition but for FUN!

Phil spillman

[Randy Cuberly]

I have personally built and flown two Ringmaster (S1) airplanes for "Old Time Stunt competition" and powered them both with OS LA 25's.  Using a 10-3 or 10-4 propeller and flying on 60 foot lines they are very manageable and easy to fly.  I used after market tongue mufflers available from several sources, like Randy Smith, and RSM.

In my opinion the LA25 set up and run with the low pitch prop this way is an ideal "Old time stunter" or trainer.   Properly used it will likely last forever!

The LA25 is easy to set-up and extremely reliable when run this way.   

It will run fine launched at 10,500 RPM with the 10-3 prop.

The stock venturi and OS needle valve will work fine but I prefer the stock venturi with a super tiger needle valve assembly.  This requires drilling the needle valve hole in the engine out to .156 diameter for the ST needle valve body.   I prefer this setup because I don't like "springy" needle valves like the OS.

Randy Cuberly