wildnloose

Maybe someone more experienced would like to explain this to me....here's my deal.

I was getting my spad ready for a pylon race. Its a dogfighter with a stock tt .46. I tried several of the props below:

APC: 9x6, 9x7, 9x8, 10x6, 10x7, 8.75x9W
MA: 10x6, 10x7
Unknown: 10x6 (looks like a black APC), came with an arf

Out of these, I got the best results with the pylon prop (8.75x9W) turning about 14.2k on the ground. While it seemed to have the fastest top end of the bunch, it took a while to get there. Since the course is pretty tight, with 2 pylons, I decided to go with the 10x7 for a little more thrust to pull out of those tight turns.

Next, I lost half my muffler in flight, lucky I found it...now I have to re-tune without baffle so I thought I would check the props out again. This time the MA 10x6 is the winner by a long shot. Its screaming 13.6k on the ground and it really unloads in the air...I mean...REALLY!!! It pulls like crazy and top end is the fastest ever. I mean you can hear it screaming as it goes by, and people swear its much faster than before.

Anyone care to explain what caused the sudden change, why its so much better. I know a guy who removes all of his muffler baffles, has the same engine/prop on a trainer, and he does not see it performing like this. I believe I have heard what an engine sounds like when its getting on the pipe (I have a Magnum/West 50 combo, when I heard the rpm jump it scared the crap out of me), and this engine has a similar sound in a dive (big rpm jump), but I will stop short of saying that its getting on the pipe. I mean, its a regular engine, not a high performing one...right???

While its not that big a deal, I really would like to know what is happening...

Thanks in advance