What, if any, are the advantages in mounting the engine where the muffler is below the engine? Is it for balance, so exhaust won't be at wing level, or just for looks? Plane in question is a 40 size big stick type. My 40 size stick has muffler below, where as a 60 size stick I have has it at the side. I gots to know.[:@]
I'm just getting started into r/c planes, ( have cars, trucks, and sailboat), so ya'll get ready for lots of questions from me!

I think it's mainly for aesthetics. To me, it just looks better if the head isn't sticking out the top. Having the oil blow out the bottom is an added benefit

When the muffler is above the engine raw fuel can run back into the engine. My experience has been hard starting when the engine is rich or over primed. Sometimes enough fuel will run back into the engine to cause hydraulic lock. Some muffler designs are worse than others but it is preferred for raw fuel in the muffler to run out the tailpipe. I recently mounted an engine upright for cowl reasons and it is a pain in the posterior and will need to be remounted.

Ninety degree mounting also usually looks better.

Rotating the engine usually helps keep fuel off the wing.

Rotating the engine almost always helps to maintain the correct CL of tank to CL of carb relationship. The height of the carb relative to the tank is very important for proper engine operation. Get the carb height wrong and there will be no end of troubles.

Bill

All my mufflers that are below the engine have the exhaust running out the bottom of the plane. I find that the planes that have this are much easier to clean up. The exhaust oils barely touch the plane, and usually only in one very small spot. The rest of the plane stays clean! Thats the biggest advantage that I know of.

One of the reasons is to get the tank at the correct level. The center of the tank should be no higher than the fuel jet in the carb. On many planes, you can't get the tank high enough if the engine is mounted upright. If your tank is too low, the engine will lean out excessively during flight.

The advantages of side mounting are numerous and as already mentioned better fuel tank needle spraybar positioning, no hydrolock problems but there are other reasons too. The muffler below provides better noseover protection with with a taildragger. Don,t laff, mufflers make effective brakes and this is standard procedure on many pylon aircraft to use the muffler for a brake by application of full down after touchdown. Now for the most important reason and that is safety. Most engines when mounted this way end up with the neecdle valve straight up and far, far easier to adjust from behind the wing. While I have airplanes with engines mounted numerous ways when it comes to my multi engine stuff I will only use side mounts and it is for that reason. Only safe way to operate multiple engines is with that needle straight up (and with out the cylinder in the way).

John

Thanks ya'll, seems the most common reason is correct carb-to-tank level.

Anymore suggestions? Please keep them coming. Thanks again and thanks in advance to any others.