Hello All:

     While flying my HP .40 powered Ringmaster Imperial yesterday, it was mentioned that operating this engine over a very wide rpm. range may not be good for longevity.

     Here is a bit of information.  The engine is a HP .40 with a Brian Gardner ABC piston and sleeve. The tank is a standard 5oz. sans uniflow.  The fuel is 20% synthetic with no nitro.


     The plane is launched in a very wet burgling two cycle where it remains until about one half of the fuel is exhausted. For some reason, I have been unable to get the HP .40 engines to run in a four cycle.  They work very well in a wet two cycle with an 11-4 or an 11-5 prop.  After that the engine goes into a very powerful and fast two cycle until the fuel supply is depleted.  It does not to become overheated.  The question that arose was, is operating this engine over this broad rpm range pose a problem for the engine.

     One solution is to remove the existing tank and replace it with a Uniflow tank which would demand a bit of effort as the plane is glued together.  Can you say surgery?  Or can I continue flying this engine as it is?

      Suggestions/Comments

     Tia,

     Frank McCune

Man up and do the surgery

Part of trimming these days is moving the energy storage thingie up or down -- you move the tank up or down to tune the engine's response upright and inverted, you move the battery up or down to tune the vertical CG.

So while you're being manly, if there's space in there make the tank removable and shimmable.