REFLECTOR: Induction scoop

[Al Gietzen]

Scott;

Not to worry; the most pressure you would ever see in the scoop is about 0.5
psi.; well, unless you get a serious back-fire - that might be worse.

Just a reminder that on an induction scoop the edge at the entrance should
be very rounded; like 0.25 radius or so.  When the plane is moving very
slowly; like beginning the takeoff roll, the air is being drawn from all
directions, and the rounded entrance will reduce the pressure drop.  For max
ram pressure at speed you'll want to size the entrance for flow velocity
just a bit less than the aircraft speed for the expected engine rpm and
displacement.  But then you probably knew that.

Best,

Al


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Monday, July 06, 2009 12:00 PM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Induction scoop


I'm reshaping the induction scoop(P51 style) and was wondering if I need
to do anything  about pressure  building up in it?

Unlike a cooling scoop that always has flow through it, I can pull the
engine to idle, which is shutting down the flow.

Think I could blow up the scoop at high speeds? 

Should I put a spring  loaded  door  on it to  open at  high pressures?

this is the original scoop, before shrinking and putting a new flange on it.

http://www.eharwood.com/catalog/product.php?productID=344

Scott