> >>>> Applying today's technologies might be
> interesting
> >>>
> >>> to
> >>>
> >>>> see what happens...
> >>>>
> >>>> 1. Scitimar props are available now.
> >>>> 2. Carbon fiber has certainly reduced the
> weight
> >>>> 3. Six, seven and even nine blade props can
be
> >>>
> >>> found
> >>>
> >>>> Note: Seven blade is the quietest of all
> >>>
> >>> combinations
> >>>
> >>>>
> >>>> David Mathes
> >>>
> >>>
> >>> Sounds interesting, any ideas of any to see ?
> >>>
> >>> jofarr, soddy tn
> >>
> >>
> >>
> >>
> >> For COTS, http://www.warpdriveprops.com/
> >>
>
www.aircraftspruce.com/catalog/appages/warpdrive.php
> >>
> >> Prop adjustment
> >> http://www.ivoprop.com/inflightmagnumodel.htm
> >>
> >> For custom, Dowty Propellers is the leader.
> >>
> >>
>

www.smiths-aerospace.com/Systems---/Propellers/index.asp

> >>
> >> Picture of SAAB 2000 attached
> >> The six-bladed propellers are constant speed
with
> >> auto-feathering and reverse pitch.
> >>
> >> David Mathes
> >>
> >
> >
> >  David,
> >
> >
> > I've seen these multi scimitar type props mostly
> on turbines.  Would > > there
> > be any advantage to using them with prop output
> speeds of 2000 rpm > > driven by
> > a rotary wankel engine?
> >
> >
> > Doug
> > Ive been watching the development of the carter
> copter for a few years-
> fascinating stuff.  They have also been working on
a
> scimitar prop
> prototype that looks very promising at
> http://www.cartercopters.com/propeller_system.html
> > Mike Parker


Mike

Carter appears to be on an amazing journey where a
propeller driven plane COULD fly at 500 mph, based
on
the use of scimitar technology.

 >From the site...

"At a μ of 1 the forward speed of the aircraft
and the tip speed of the retreating blade are equal,
therefore, the air velocity at the tip of the
retreating blade is zero and there is reversed
airflow
over the entire length of the blade."

"Carter technology should allow flight speeds up to
a
ratio of μ=5 (where the aircraft is traveling
at
speeds up to 500 mph and the tip speed of the
advancing rotor blade remains under mach 0.9)."

David


I'll believe it when I see it. They have been
fooling
around and crashing for years. The Carter style
props
were tried by the Horten brother pre WW II. Klaus
also
tried one a few years ago. Apparently the air is
confused
around the root or has low energy so having a wide
cord
with a lot of camber in that area does not pay off.
Unless of course your cooling scoops are right
behind
that area of the prop. In that case cuffs also work.

If you are stuck with high RPM and two blades a wide
cord is necessary to absorb the engine HP.

If there was real merit, as far as prop eff. was
concerned,
there would be more of them  around by now.

Paul Lamar ...No rotor no motor.

Paul

I agree. The proof is when it flies...

Earlier attempts were with heavier blades, blades that
suffered torqueing when the angle was adjusted, and
parasistic drag that just kills an attempt at any prop
driven plane approaching even 400 mph.

However, these are composite blades made of carbon
fiber which are lightweight. The blades are stiff and
don't torque unlike earlier attempts.  The scitimar
blades allow for subsonic blade tips at much higher
linear speed although this requires. The current wide
blades are experimental to get their processes down.
They may shift to thinner and more blades as time goes
on.

My reference point is what Dowty (under Smith Bros)
has been doing for commercial and military craft. I
flew in a Dashair in Colorado that had no problem
sustaining a long climb out at elevation (5000 to
20000 f msl) with those six blade carbon fiber props.
Eight blade props are being used on C-130s and some
commercial craft.

David Mathes


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