Hu:

      Will this harm the engine?

                                                    Tia,

                                                    Frank

     Hi Tim:

     Thanks for the reply.

     I asked for a friend of mine who is doing this type of flying.  He is using a Brodak ARF Smoothie that flies very well and quite fast..  I timed him and he was turning 4 second laps on 60" lines.  I suggested that he get rid of the 10X6 prop and try a 3.5 or a 4 inch pitch 11 inch prop.  If this thing would lean out, he could fly combat with it! Lol

    I thought tht these enginse should be operated in a wet 2 cycle mode to prevent premature engine wear. I should check to see if he has a AAN p&C before I make any more suggestiions.  It may be an iron and steel setup.

                                                                                                                 Stay well,

                                                                                                                 Frank

     

     Hu:

      Will this harm the engine?

    No. It will harm the performance of the airplane, but not the engine. The "don't ever run it rich!!!!!" advice stems from George Aldrich, who ruined his first ST X29 ABC because he thought it was way too tight, and proceeded to take out all the taper to loosen it up on his Sunnen Honing machine. Of course it was worthless after that. Then he got the idea behind it, and then went hard-over the other way, setting his engines up tighter and with more taper, which might have been a good idea for a racing engine (some of which *glow a dull red* when they are running), it was a disastrous idea for a stunt engine, since it never got hot enough to loosen up. You probably can damage a ST X29 running it rich, and I know that many of the GMA ABC engines were eventually damaged by running them normally for stunt. Interestingly, the cylinder and piston was durable enough, but the crank wasn't - jamming the piston into the taper with it *squeaking in flight*, 240 times a second,  was a bit stressful.

    The 40LA doesn't have enough taper nor is it too tight to run in a 4-stroke. You probably don't want to, for performance reasons, but it almost certainly won't hurt anything.

    Brett