I believe that mufflers will reduce power only if you are going for all the power you can get.
If you have already limited with the engine's output with a small venturi, oily low nitro fuel, and an oversize prop, a muffler won't cut it down any more.
I've tried FP 40's both ways, and the factory muffler is very quiet with no noticable loss of power.
A proposed article about just that subject and the initial tests performed in support of the proposal was among the modelling material I spent some time with a few summers ago. The manuscript started, and ended (never completed) without any real revelations or potential controversy, when muffler adoption was still in its infancy, about 1978 or so. The time frame preceded most Schneurle designed engines' releases, and the tests actually made at the time only involved two engines, Fox's 35 stunt, and OS' Max-S 35.
There was some difference on the test stand, and a fairly noticeable difference in the amount of heat retention, especially for the Fox, which meant greater difficulty with hot restarts, but perceived in-air differences, either in sport flying, or using a stunt model flying a pattern, ended up far smaller than anticipated, being only incremental amounts. When I remembered to ask about the potential differences from one muffler design to another, I was told that the WEIGHT of some muffler designs was more of a hindrance, requiring adding tail weight, than any actual power loss.
(I'm pretty sure that there were no tongue mufflers listed in the text or other notes as a proposed test item. All of the proposed mufflers had to be strap-ons, since neither of the test engines actually used had muffler mounting ears on them, and I personally have no idea what the production lifetime was for DuBro's muffler of that type.)
Topic: OS 40 LA (Read 808 times)