"B2431" wrote in message
...
From:


One "VTOL" suacer that got to the preliminary designe stage was
this
Focke Wulf "VTOL"
http://www.luft46.com/fw/fwvtol.html

I have no doubt that the device would work and is superior to the
tilt rotor
concept and its troublesome gear boxes. It seems to have ducted a
gas
turbines' exhaust to power a large contra rotating ducted propellor
in the
center of the "saucer" with the tubine then being
deflected to provide forward propulsion.

Indeed if built today it would be excedingly usefull as unlike a
helicopter or
tilt rotor it could manouever along side a skysraper or land in
tight spots
free of the dangers of rotor impact.


And do what? The drawing shows a vehicle that would carry a crew of
one and NO
payload.

It has one crew member. It could no doubt carry a warload or cargo in
the ring shaped fueselage or adated for more crew or passengers.



Next time you are in the Ft. Eustis VA area go look at the saucer
shaped
aircraft (Avro?) they have. It could carry 2 men, hover all of 2 or
3 feet off
the ground and manoeuver rather nicely. Other than low hover it
could not fly
and wobbled a lot. Unlike the Nazi ideas this saucer WAS built and
proved how
complicated things really were. The downward ducted fan concept has
been tried
several times and not one vehicle had the performance to justify
proceeding to
an operational prototype.

This Canadiarn AVRO device used the coanda induced airflow effect and
a sort of hover-craft effect which is somewhat different to this Focke
Wulf FW-VTOL concept which used a large rotor sised ducted fan in a
lenticular like body.

Most ducted fan lift concepts have worked and seem to have provided
forward speeds twice that of helicopters. A ducted fan of course is
not going to be as effective at providing lift as a full sized rotor.

Better to have a good hovering helicoper and a poor crusing vehicle
than a poor hovering VTOL craft and an average cruising vechicle.
Hence aprt from the Harrier helicopters are the only VTOLs in service.

As I pointed out however such a vehicle might have advantages in
closed approaches in rescues or landings in confined spaces or if
twich as fast as a Helicopter better survivability in battle.

Two vehicles using ducted fans are being built now in the USA and
Israel.

http://www.moller.com/
http://www.urbanaero.com/Urban_Main.htm

They both have a plausible market. (The Israeli one seems the better
to me)


If equiped with an appropriate control system of gyroscopes,
accelerometers and perhaps radar/lasers such a vehicle might be made
to hold station centimeters from a building to rescue people or to
land on someting as small as a tennis court.

The old FW-VTOL concept seems as good as the above two.




Dan, U.S. Air Force, retired