"Simpson, Bill (W.R.)" wrote:
Paul Lamar,
I got a lot out of your forum at OSH. When you mentioned Dave Lednicer's name, you got my attention and improved your credibility with me immediately. I met Dave while we were both engineering students at The University of Michigan, he gave me my first ride in an airplane and is truly a terrific guy.
You made a strong impression on me with the commentary on cooling duct design, etc. I tried to Find the two books that you mentioned, and have had some difficulty. I found Compact Heat Exchangers by Kays and London, but have had difficulty finding Aerodynamics of Propulsion. I am still guessing at the spelling for the authors: Kuchman and Weber? Please correct me on this. Any suggestions for a source of this book?
One event of note during the show for me was that the Powersport RV6 has apparently been having fun getting their cooling together. Did you see it? If not, here is what I saw:
Primary air intake is a "laughing mouth" below the spinner about 9" wide and 4 1/2" deep. They have added a NACA duct with an auxiliary inlet about 3" deep by 6" wide below the original in bottom of the cowl, where the cowl is still enlarging in section area. The original outlet looked commensurate with the original inlet and was just an overlap below the fuselage. They placed a rounded edge on the firewall. They then added a fixed "cowl flap" section opening below the original outlet.
The overall impression that I get is one of "This thing is not cooling well enough, perhaps some more inlet and outlet area..." The surprising thing to me is that they made the top surface of the inlet flush with the propeller spinner. It seems to me that the spinner probably creates a pretty substantial boundary layer and it is being ingested. I suspect that the inlet should probably be separated like is used on many turboprops, etc. The use of the NACA duct below seems ill advised. I wonder if they were cooling fine in cruise but in climb they had trouble, so the NACA duct on the bottom and "cowl flap" were added to investigate having a moving cowl flap...
Anyway, I was wondering what your thoughts were on their design.
I look forward to your response.
Bill Simpson
Technical Specialist, Converter Clutch and Damper
Used books on the internet is the best bet. Sometimes people
sell them on Ebay
Kuchemann and Weber. McGraw-Hill. Aerodynamics of Propulsion
1953 Lib of Congress cat card 52-6541
Kays & London "Compact Heat Exchangers" Kriegar Publishing
Malabar Florida. ISBN 1-57524-060-2
Yes I saw it :-)
I agree with your assessment Bill.
Did you get to discuss planetaria's with the people in the Power Sport booth?:-)
I have taken the liberty of adding you to the list.
If it gets to be too much let me know and I will take you off.
BTW we are widely using the low cost C6/E4OD planetary gear set in our PSRU's.
Tens of thousands of hours of accumulated successful use so far.
Thanks to Ford :-)
This jpg is what we using to isolate the rotary engine torque pulses.
There are plastic washers and rubber bushings under those large metal washers.
It is working great. Perhaps you can give us additional insight.
Paul Lamar
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