Full size engine silencing

Wikipedia is your friend Garry;

en.wikipedia.org/wiki/Ward_Leonard_control

Thanks Owen

Garry

I would have thought that a tuned pipe would work very well on a full size aircraft. My reasoning is that you tend to run at one rpm when cruising. If your negative standing wave appeared at the exhaust valve at cruise rpm there would be a huge increase in efficiency. Trouble is I think the pipe before the silencer would need to be about 8ft long!
In the old days when Minis were the thing we ran C-AEA648 cams, there were huge gains to be made by careful placement of the expansion box.

The tuned pipe came to my mind when I asked the question Kippy

Garry

The engineering lab at the Technical college I was at in the early sixties had a set. Don't know what it was off, possibly a lift. An AC induction motor drove a brushed generator which powered a 20hp brushed motor fully variable from zero to full power in either direction and all done with 5A variable resistance. Beautifully restored (I think it was from the 1920s) the 'set' was about 15feet long and must have weighed a couple on tons! Could now all be done with just a single motor and a black box of thyristors.

At the factory where I worked we had a couple of 2 litre Ford Pinto engines running to test exhaust emission control systems. Each engine drove a smooth 2ft diameter steel disc running fully submerged in a big tank of water. A mathematical colleague had calculated that at 4500 rpm the skin friction of the water on each disc would absorb 80hp. Much to my amazement he was quite right and in a hour with both engines at full power the 500 gallon tank was steaming. It gave me a new respect for the effect of skin friction. :woohoo:
ps This was in the days when it was hoped that simple air injection into the hot exhaust would be adequate.