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
Thanks. My doubt came because fans in airliners are composed of
many, many blades
and they add to the thrust of engine by sending a larger mass of air
at lower speeds,
I have no idea about the rotating speed of a fan in rpm of, for
example, the engine in
a Boeing 777, but for sure, the ducted fans used in experimental
aircraft with powers
below 250 Kw, and this is a lot, do have less blades and turn at a
different rpm regime.
From the experience in cooling fans for charge and air cooled
Wankel RCES, it can be
proposed that a fan placed immediately before the 'ring' would be
more efficacious, and
that if you use the inner part of fan cowling as cooling surface in
a liquid cooled engine,
you may add some thrust, as in the scheme you provided recently about
the radiator in the
P-51 Mustang. However, it's not the same cooling an engine that moving
air through a fan,
an I even doubt if putting the fan in the leading edge of duct,
instead of in the trailing edge
would be better.
The inventor and NASA/NACA data about the Custer's channel wing may help
in this, they explain why they put the propeller close to the trailing
edge of channel, and
not in the leading edge, a channel wing is like just the lower part
of a ducted fan, and there's
also, or there was, a link in the Wikipedia article Propfan to a work
by an engineer in a Canadian university,
that explains the basics of prop-fans, a device much closer to the
ducted fans in ultralight airplanes
than the big fans in airliner's turbines, and there also some videos,
several of them by teachers
of engineering in India, about elements such as contra-rotating fans
in aircraft turbines, and about
turbine designs, besides the SAE papers of the 40's and 50's.
By the way: I guess I paid less than $35 for the original Hovey
document, and it was a later edition.
Google books has partly available the book by Marc de Piolenc and George
E Wright:
'Ducted Fan design', the address of first author of book is
piolenc@reporters.net and
here's the link I found by searching: 'Hovey ducted fan' in Google:
Salud + Jose Gros-Aymerich. Madrid, Spain
www.engr.psu.edu/rcoe/theses/Myers_Leighton.pdf
Are you still here George?
Paul Lamar
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