George,
I saw a German mid-fuselage ducted fan - it looked a beauty, however you
may
know it as a shrouded propeller.
I believe it was developed in the early seventies, do you know of this
aircraft.
George ( down under)

You're probably referring to the Rhein-Flugzeugbau series.  They started
with a 4-6 passenger test aircraft about 1960.  It never went into
production.  Then a powered glider.  then a 2-person powered glider. The
single pilot glider began with a Nelson engine.  The 2-seater had two small
Fichtel-Sachs rotaries coupled with overriding clutches.  The mid-engine/fan
configuration you're  talking about began with an aircraft called the
"Fanliner".

They went with rotaries originally, including the prototype of
a military follow-on called the Fantrainer.  Both versions of the Fanliner
were rotary, using a gearbox so they could drive a large fan.  The second
Fanliner was styled by an Italian industrial designer and its ergometrics
turned out to be impractical.  The production run of the Fantrainer ended up
turbine-driven.  50 were built for the Thai Air Force.  I believe they have
all gone out of service now.  The original wings were grp, but the Thai's
later retrofitted them with metal wings.  There are two Fantrainer
prototypes bouncing around Europe.

Every now and then one comes up for
sale.  I don't know what happed to the Fanliners.  The program was serious
enough that Grumman-American and Dowty-Rotol were involved.  I written up
all of these programs plus a description of the Dowty fans courtesy of one
of their former engineers who worked in the test group.  The rotaries seem
to have worked pretty well, but as the Fantrainer program progressed, the
clients wanted engines more compatible with their existing inventories and
what their mechanics were trained to service.  There were projected versions
that required more horsepower than was reasonably available at the time and
the turbine seemed an acceptable solution.

Pilots quickly adapted to the
fact that they got most of their power on the high end of the curve. Noise
was a problem, compounded by the wake effects on the leading edges of the
cruciform tail structure.  This was remedied by using a different gearbox to
the fan and sweeping the fan blades.  A friend of mine at P & W shook his
head at that solution and wondered why they didn't just sweep the leading
edge of the cruciform empennage.  It would have been cheaper and easier.


Bottom line, it was possible to achieve the same things with more standard
equipment.  The RFB birds are technically interesting, but not very
cost-effective to build.  They do fly nicely and have some intriguing
features like speed brakes built into the external housing of the ducts.
You don't get trim effects when you engage them.  I think they were a ahead
of their time.  Pilots tend to be somewhat conservative and the RFBs looked
a bit space cadet.  Perhaps it was the flight manual which essentially
claimed that the Fanliners top speed was its cruising speed!
George Wright

Is this the one George? I took these pictures at Sun N Fun in 2001.
-- 
Paul Lamar ...No rotor no motor.

Paul,
That's not the one it was much more elegant than that. I still have a mental
picture of the aircraft - it was a two seat, nice ( easy) gullwing cockpit
access and George is correct to say it probably did look a bit futuristic
for that era, but for today's standards it looks just right.
Interestingly top speed was limited - probably because of the shroud. That
German  Aviation technology is right up there with the best.
Interesting information, thanks George. You don't have a photo for Paul do
you ?
George (down under)

I have a press release photo of the original Fanliner (B & W) which was
nowhere near as sexy as the second prototype.  Let me dig through the files.
I do have a three-view drawing somewhere.  Also managed to snag an English
language technical sales brochure on the Fantrainer which has great
illustrations and cut-aways.  I neglected to mention that failure of the
Luftwaffe to pick the Fantrainer as a basic trainer was one of the major
reasons that Dowty-Rotol withdrew their "Ducted Propulsor" from the market.
This impacted a number of aviation projects including a twin Porsche engine
blimp design in Britain which ended up with clipped MT props in a duct.
This became the well-known Fuji airship.  I flew in one in the late 80's.
Used tilting ducts for vectored thrust.


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George, two things! Please place your new message AFTER the old one
and sign it. You drive me nuts:)

Paul Lamar ...No rotor no motor.

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