Hi TJ

 

First, yes there are general coordinates for a Streamline Duct in K&W - some manipulation required to size them for your core size and opening, but not hard. 

 

 Yes, to the best of my ability and patience, I really did not have much space (3" on one side and about 5" on the other) to made a transition.  So I started with the bell against the core and the opening had to be an average of 4" in front of the core - so as you can imagine there was not much room left between inlet and core  to place the "pinch". 

 

The only advantage (if I may) that I see for the pinched duct is that simply truncating the streamline duct (especially if you are talking leaving only 3 -4") leaves a lot of the core exposed to a higher velocity airstream and I believe results in more cooling drag.  By making the intake smaller but squeezing it to cause higher velocity boundary layer my "theory" is that it delays separation, slows the airstream down and results in a better "constrained" space duct. 

 

Don't know if the theory holds water but it appear to do at least OK with air {:>)

 

 

 

Ed

----- Original Message -----

From: Thomas Jakits

To: Rotary motors in aircraft

Sent: Saturday, May 05, 2007 8:14 PM

Subject: [FlyRotary] Ed's Pinched Ducts

 

Hi Ed,

 

question:

 

Are your ducts lofted (built from coordinates?) for the diffuser part of the duct?

If you look at it from the radiator towards the intake - is the diffuser a "true" streamline until it becomes necessary to fair into your "pinches" or is the diffuser "eyeball"-engineered?

I believe there are general coordinates available from the K&W publication for a complete streamline....

 

TJ

 

 

All,

OFF-Topic:

 

Can't find a 3A, 125VAC 4-position switch, 2 wires IN, 4 wires OUT, rotary-type, Fan on/off and 3-speed control,

any ideas for mail-order?

 

Thanx!