Mailing List flyrotary@lancaironline.net Message #30845
From: M Roberts <montyr2157@alltel.net>
Subject: pitot inlet
Date: Wed, 22 Mar 2006 19:30:45 -0600
To: <flyrotary@lancaironline.net>
Monty,

When you suggested using a pitot style air intake for the cooling, what exactly did you mean by 'pitot'. I envision it to be a tubular structure that extends forward of the wing's leading edge, but would the extension be a slight bump or a lance worthy of slaying dragons? As it stands, I have about 32" from the leading edge for a duct to feed a 4" thick, 13.5"x9" radiator. (I'm still trying to source a radiator without going the custom build route.) I don't need any more length to get a fully developed K&W streamlined duct, but if I need to extend the opening out significantly from the leading edge it will need to be incorporated into the design.


Ernest,
 
I was a little unclear. I meant a standard leading edge inlet. Nothing too fancy. If you look at the leading edge of the Corsair you will see the inlets for the oil cooler. That is what I had in mind. I would keep the ducts as short as possible while still maintaining reasonable efficiency. You don't need a really long diffuser to get good performance. That extra length only adds a small amount of pressure recovery, but it adds a lot of weight and internal drag. Pressure recovery is nice, but it isn't everything. You only need enough pressure differential to make the air go through the radiator. Remember the idea of making a "jet" out of this thing is a loosing proposition. People like to talk about the air "squirting" out through the exit. That is pretty unlikely. More likely is reducing the internal flow and lowering momentum and internal viscous drag. Twist the big knob first, leave the fine adjustment for later :-).
 
I would locate the inlets in the outer portion of the prop arc. There is much more velocity there for ground cooling. You have a unique situation where that is possible.
 
 
Monty
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