Subject: Canard cooling Step 2..
From: ACRE NL
Date: 2/28/2002, 10:09 AM


Put a P51 scoop on it. You can buy these beauties off the shelf
as hood scoops from the Hot Rod industry.

Paul Lamar


  Ok, Groupmates (groupies?) (hmmm...guys and Chrissie?)...

    How's about a P-51 scoop feeding a proper diffuser, stacked air and
oil
cooler, exit flap, but with a twist?  Feed the exhaust into the rear of
the
scoop where, when the flap is 'closed', the exhaust-powered augmenter
does
it's thing to move air (no cooling fan in front of the canards to push
air
thru...)?

    What info is available on sizing and shaping the scoop inlet, and
properly proportioning the exit flap?

     Andy
    Very early rotary E-Racer without a submerged inlet...


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

Here is a summary for one of many studies. Getting this to work well could
be a long R&D process. I don't recommend messing with it. Just use a P51
scoop and conventional cowl flaps until after you get your airplane
flying and cooling properly. You will have enough problems without 
asking for more trouble. 

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org

RM-E6L13a-summary.gif