On Sep 8, 8:37*pm, wrote:
On Sep 8, 3:01 am, Leviterande Leviterande.



wrote:
yes, I have been looking into *todays vtols, they either have *a
complicated *large merry go arround rotor system * or a *very very
highly concentrated plumes of air *as in *the harrier/F35 jet

both are very expensive to maintain, complicated and yet not so
practical unless in military.

so some kind of a *propeller/ fan/ rotor with no moving part *must do
the job somehow to get rid with the complexiity and cost and SPACE!

I was just thinking of *testing a *thick-chord fan with 4 blades and
a medium AOA. it should be geard to the motor * *unless the motor has a
very high torque. My idea is that efficiency should go up when one use
a geared system
the propeller is a standard slowfly 10x4,7
rpm is around 7000-8000
if we instead took a 7 inch impeller *with larger blades moving more
air *at one revoltuion *, i tmeans it makes *more drag and resistance
to the motor shaft.. now if one calculate the required data and put
reduction gear to the motor. the thrust out put should be equal at less
rpm and *smaller propeller and with the same efficiency!

* * Helicopters and other VTOLs are complicated because they have to
be. One of the things that bugged the early experimenters was
gyroscopic force; any time we change the plane of rotation of a prop
or rotor we get precession, which results in a loss of control unless
the system is designed to deal with it. A fixed-pitch rotor can't do
that, and the larger it is and faster it turns the worse the effects
of precession. Current helicopter designs all take advantage of
precession to tilt the rotor disc, applying blade lift at 90 degrees
ahead of the desired blade rise.
* * *The other factor is the necessity of being able to glide. No
fixed-pitch rotor is going to do that (unless it's an autogyro, with
an undriven rotor and very low pitch angles) and even some sink could
cause blade stall and loss of control.
* * *Do the research. Find out, the easy way, whcy others couldn't
make work. Google "Moller," for instance.

* * * * *Dan

Because models are so overpowered compared with full size, could some
of those problems be solved with air blowing over controllable fins? A
smaller diameter prop would get a lot of velocity across the fins, and
that could be used to offset rotation and could tilt the axis for
translation. It might take a little computer power, or maybe just a
skilled pilot, for easy control.

It would have to be a labor of love, I doubt there's a DOD or
commercial use for such a device.