BaldEagel

I have now repeated these tests in the open air of my flying field and not in the garden as before the results are supprising, I did not expect the reflected sound off the surrounding trees to make that much difference to the sound volume.

MVVS 58 Pro, 22x10 3W prop, 5900rpm J-TEC large pitts silencer 90DB at 7 Meters.
MVVS 58 Pro, 22x10 3W prop, 6300 rpm MTW 75K with 25mm dia 210mm manifold, 83 DB at 7 Meters

The open area took 2Db's off the pitts silencer and 3Db's off the cannister, I suppose that is logicall as the lower sound would have a lower reflective index? therefore an extra Db off. I don't think I have mentiond before this engine is mounted on Isolation mounts to help lower sound atenuation through the airframe.

Mike

BaldEagel

Well the Yak has flown, the premise that I would only have to use half throttle was not quite correct, I only used just over tick over for most of the level flight and up to half throttle to go vertical, this is one very powerful engine, I am now thinking of something much bigger to put it into.

http://media.putfile.com/Yak-Maiden-19

Enjoy the vidio and just listen to the sheep commenting.

Mike