We got lots on scoops and diffusers but no data on exhaust powered

augmenters.

You will need an inlet area about 20% of the rad area and an outlet area

at least

twice the inlet area. Won't hurt to make it three times with cowl flaps.
The diffuser should look like a bell but a simple wedge also works.

BTW make sure the red hot exhaust pipe does not radiate heat to the

radiator

as that will defeat the purpose. Ever been around an infra red sun lamp?

Paul Lamar

Andy,

Check out NACA report 818. Also do a search for ejector on the NACA online
library. Lots of work on ejectors in the late 30's and early 40's. I am in
the process of analyzing the same installation. Preliminary numbers are not
exactly favorable. Looks like you can expect to get about 1" of water delta
P from the augmentor. This is because the cooling air flow to exhaust flow
ratio is about 13. About the minimum to even get any effect from the
augmentor. To do better you need a ratio closer to 7-8. At these flow ratios
a delta P of 4-5 in water is not impossible, totally eliminating the need
for cowl flaps. This works much better on air cooled engines because the
metal is hotter, so you need less cooling airflow and can have a more
effective ejector. This being said, if the radiator is optimized and has a
min pressure drop, plus a good inlet and exit, it is possible to generate
some thrust, or at least minimize cooling drag. Plus you get ground cooling
as a plus. To be honest, I'm not sure that it is worth the hassle of the hot
plumbing in the cowl, and the extra weight etc. But I remain hopeful that
when I dig a little deeper I will find out otherwise.

Monty

Paul, since you are nearby Klaus's hanger. He was flying with someone at Rough River that had a Long or Vari canard that had what looked like a very well developed subaru drive system. The unique aspect was the augmented exaust, a very clean installation. Unique sound and look too. Have you seen a canard over there with a very large round hole under the prop?
...Chrissi

That is Charlie Airesman airplane and he is based in Maryland.

Paul Lamar
 
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