http://gltrs.grc.nasa.gov/reports/2005/CR-2005-213987.pdf
Here is an article on muffler testing from NASA.
Here is an article on muffler testing from NASA.
That rock-wool is a great sound deadening product. I was at a builder show once where a company was promoting spray in rock-wool for insulation and sound deadening in homes. They had a five gallon painters bucket lined on all side with the stuff, I think about four inches is all. They had a small 130db siren that they turned on, (it was loud!) and then they dropped it into the bucket and covered it. You could hardly hear it! Amazing difference.sorry dont read...already discussed
In bingelis book he talks about swiss mufflers. they were the answer to the strict swiss noise regulation. They are 3-5 feet long 3 inch diameter aluminium tubes with thinner perforated steel tube inside and inbetween rockwool.
They dont take power away and are very effective.
I have to see if they make sense for a turbo engine and see if i have enough space for a tunnel in the fuselage while keeping adequate distance between the muffler and the composite. Such a tunnel could serve as a stringer for the fuselage structure.
And, rockwool will sustain temperatures of over 2,000 degrees before breakdown, about twice the breakdown temperature of fiberglass. Rockwool holds much less moisture than fiberglass, so less buildup of acidic condensate residue which corrodes the metal muffler housing and pipe.That rock-wool is a great sound deadening product. I was at a builder show once where a company was promoting spray in rock-wool for insulation and sound deadening in homes. They had a five gallon painters bucket lined on all side with the stuff, I think about four inches is all. They had a small 130db siren that they turned on, (it was loud!) and then they dropped it into the bucket and covered it. You could hardly hear it! Amazing difference.
GESchwarz...in a previous post you said: Although the piccolo by itself is a a form of muffler, in this design it appears as though the piccolo tube was used primarily for mixing with ambient air to get the temperature down.
That being said, what would change if you used a turbo charger? A turbocharger uses the exhaust to spin the turbine. How much would the turbo cool the exhaust afterward, and how would that affect those pulses?
DarylP
See if this comes through:i have never understood what kind of epoxy they use for motorcycle carbon mufflers. I know of high temperature epoxys but not of resins that resist the temperature of an exhaust
Per Bengelis' Swiss muffler design, the batting is held in by stainless steel mesh (course grade version of window screen) and rolled into a tube, so apparently would prevent the exhaust pulses from blowing the rockwool out.Rock wool is like fiberglass or cotton batting used in making quilts. I can't imagine it lasting very long due to the velocity of hot gasses passing by or through it. I would think that it would all blow away in short order. It is also carcinogenic.
I don't really think the presence or absence of rockwool or fiberglass will influence my decisions to breath from the tailpipe... In any event, I would not be doing much breathing from the tailpipe.