Lou wrote:
Ok, so it's not an airplane but it is related. I'm going to Oshgosh and
will be camping. Anyone have an idea on how to make my 70db generator
quieter besides not running it?
Lou

Your approach will differ depending on your requirements. Are you
trying to make it quieter for you neighors or yourself?

Neighbors will be happier if your run the exhaust into a galvanized
bucket filled with water. The exhaust, via suitable hose (few are) or
flexible metal tubing. should extend BELOW the water level. There
should be a top on the bucket, vented around the edges to direct the
much reduced noise DOWN. ASCII art:

/--------------! !--------------\
/ ! ! \
\ ! ! / Exhaust exits bucket here
\_______!__!______/
\ ! ! /
\ Water /
\____________/

The lid should be as stiff as possible, or it will re-transmit the
throbbing.

If it's your sleep that's disturbed, you need to take other measures.
ALL transmission paths must be addressed. This means soft mounts for
the genset itself, AND soft connections for everything that attaches to
it. The barrier between the genset and the rest of the RV needs to be
stiffer, heavier, and more resilient.

http://www.soundproofing.org/ has lots of good advice, and products to
implement all these strategies.