(upper right) and making it into a blow out door that can open with
 the slightest pressure (literally < 0.1 psi) to permit less flow

restriction

 at high speed cruise condition.  When the ram air is low and you need
 the fans, the downstream side of the rad will be a low pressure area (due
 to the fans) and will suck the door closed and permit the fans to work
 effectively.   This type of blow-out doors were added to the radiator fan
 shrouds of high performance Corvettes in Europe some years ago as
 the fan shroud restricted the air flow out of the rad at the very
high cruise
 speeds possible legally in Germany and other places.  Without the blow
 doors the cars overheated at sustained high speeds even though the

radiator

 was adequate.  The doors closed with springs to permit the engine driven
 fan to be effective at low speeds.

 > Bill Freeman

Thanks Bill I will add that to my list of surprises.  Of course the
fan maker says the fans have no effect on airflow when they are idle.

Paul,  the blue foam you mention, is that styrofoam or polystyrene?
When it comes to composites I am a total beginner.  I feel it is time
for me to learn these skills.  There are many books and videos on the
subject-- is there one you would recommend?  Jerry

Styrofoam is polystyrene and you must use epoxy resin with it.
Polyester resin (boat resin) will melt it.

Paul Lamar

 Well, I might be biased, but I starred in the EAA's composites video, had
a local video production company hire me to create it and they did the
video part, I did the composites part.  It was fun and sold for years but
I think it is out of print now.  Might be able to make you a copy for a modest
fee (can I do that as the star?)   It covers the basics of moldless composite
aircraft construction (like Long EZ).

As to the fans, I have no doubt that the FANS have very little drag.  It is that
the area of the outlet holes are much smaller than the area of the radiator.
If you really start pushing a lot of air thru it they become the
restriction, not
the fans.  You need to shoot for zero restriction on the backside of the
rad.

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

 
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