Hi Paul,

Thanks, I didn’t expect an answer so quickly. Aren’t you wrapping it
up at SUN & FUN today?..

I am interested in building an up-dated 1/2 scale flying model, or a
proof of concept single place engineering test vehicle.

Possibly an ultralight or another aircraft that could prove out some
concepts and configurations.

I expect that you have a lot of thoughts on which configurations are
really efficient. Can we advance the design or designs ?.

In 2001 Roy Lopresti (my former partner) in LOGO, introduced me to
one of the Navy test pilots that test flew the VTOL’s

In the 50’s. Roy was the Air Force Test engineer at Wright field at
the time those tests took place. He really shared some

wonderful and interesting insights into flying a VTOL.

After 12 yrs. off the project. I’m ready to dust it back off and
revalidate the concepts and designs

What would you like to see done. And where are you located.

The video’s and patent references are 10 yrs. old but they demo
principals that did work.

Larry

That is all well and good for hover but ducts are bad for high speed
forward motion. The drag of the duct far outweighs the advantages.
Perry Mick tried for years and finally gave up and put a gear box and
prop on it and went 30 or 40 MPH faster on the same fuel burn.

Paul Lamar


 Thanks for the very interesting technical info.
The magnitude called 'Lambda' in the Ducted fan charts: refers to the Mach number?
If yes, it looks as ducted fans having good efficiency at low speeds, but bad
above Mach .55 or so. It seems also that figures are about the type of ducted fans
used in common big airliners, but the range of speeds covered by experimental
and homebuilt aircraft being much lower, rarely if ever, above 200-250 mph,
 in this range of airspeed, the 52 pages booklet by R.W. Hovey:
'Ducted fans for light aircraft', published in 1982 and revised in 1986 that
 I bought from 'Zenith Aviation Books' would probably fit more.
Have a good week. Best regards.

  Salut †   Jose Gros-Aymerich
 Madrid, Spain

 Perry Mick owns and read that book :)  He spent 10 years flying a duct.

Hovey was wrong wrong wrong.


 Duct-Fan for Light Aircraft Paperback – June 1, 1977

by R.W. Hovey

<http://www.amazon.com/s/ref=ntt_athr_dp_sr_1?ie=UTF8&field-author=R.W.+Hovey&search-alias=books&text=R.W.+Hovey&sort=relevancerank>



Kucheman and Weber were right.

Aerodynamics of Propulsion.

 D. Kuchemann & J. Weber

McGraw-Hill Book Company Inc.

1953 Lib. Of Congress. # 52-6541


At 400 MPH and up ducts are used in turbo fans as that is the only thing
that works and is reasonably quite.

Paul Lamar



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