Re: Mobile S-Rotor!


daestrom wrote:
> "TomGee" <lvlus@xxxxxxxxxxx> wrote in message
> news:1134251327.753372.234880@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > Again, your point is well-taken, but as you said before, the blades are
> > not fixed wrt the vehicle, as they rotate around an axis. But my point
> > is that the S-rotor allows the slipstream to strike both blades of each
> > platform simultaneously - something no other drag-type rotor does.
> > That is using the slipstream more efficiently, producing torque on both
> > blades at the same time, and I would hope that should lower the amount
> > of hp required to push it through the slipstream.
> >
> > I said earlier that the lift effect is incidental to an S-rotor, and I
> > meant that it develops some lift as the slipstream moves over the
> > outside curved surface of its cupped blades. My device enhances the
> > effect by designing the outside surfaces more like airfoiled blades and
> > thus using the lift effect to its advantage. At least one test I
> > reviewed claimed that the incidental effect caused wave "eddies" that
> > tended to produce a negative effect.
> >
> > You mentioned low rpm as a limiting factor, while I embraced it as a
> > safety feature at high slipstream speeds. Estimates of the tsr of an
> > S-rotor are more often less than one-to-one, and the highest ratio I
> > found claimed tsr ratios possible of up to 1:1.5. I got 70 rpm at 55
> > mph using rounded cups as in an ordinary S-rotor, and that was
> > encouraging. If I can get 100 rpm at 60 mph, I'd be happy with that.
> > If I could get 120 rpm at 60 mph, I'd be ecstatic.
> >
> > If you're low on rpm, you have to be high on torque. I contend that is
> > the promise of the S-rotor: To produce sufficient torque from a very
> > small surface area to provide the electrical needs of large vehicles.
> >
>
> Studies of S-rotors show that the RPM is limited at high wind speeds because
> of *drag* within the rotor blades themselves.
>
Yes, I read that somewhere too, but I dismissed it because they said it
but gave no support to show why that is so. If you know their
reasoning, I would be pleased to learn it. I think they know not of
that which they spoke. What drag are they talking about? The only
drag involved is that associated with the type of rotor it is, which is
called a drag-type as compared to a lift-type.
>
> While this is sometimes
> touted as an inherent safety of the designs (they can't really overspeed),
> it is also a flaw when operated in moderate to high winds.
>
If it really exists. I am not convinced the low rpm is caused by drag.
>
> If rotor drag
> rises with wind speed so much that it limits the RPM of the rotor, it also
> limits the amount of power than can be extracted from the wind. This is why
> wind devices designed for power production in >15 knot winds are invariably
> the wind-turbine style.
>
No, that is not the reason why lift-types have been overwhelmingly
selected for the production of wind power. It is because the S-rotor
design works better at very high speeds and worst at low speeds. Since
ordinary daily winds average low speeds, the lift-types outperform the
S-rotors. drag-re invariable

> The drag of wind flowing around the back side of the advancing blades is
> normally a real issue.
>
How does that produce drag? It doesn't, it adds lift. The advancing
blade presents an airfoil surface to the slipstream and incidental lift
is produced. No drag is produced.
>
> Given your design, you might mount the shaft even
> with the top edge of a hole cut in the roof. So the lower half of the
> blades is shielded from the oncoming wind, reducing the drag on them as they
> move forward.
>
The lower half of the blade is shiielded by a wall slanting in toward
the middle of the rotor, and the entire rotor is enclosed except for
the entry and exit openings (top half at entry and bottom half at
exit). It is not an open design like the generic S-rotor, where the
advancing blade does offer some drag as it comes around. But since the
air flow is pushing the blade from behind, the drag is minimized in the
design.

Savonious had a stroke of genius, but he stopped short of developing
the best scope of application for his invention. I believe I have done
just that, and the world should benefit greatly from Savonious' great
idea.
>
> As they back of the blades starts to rise above the mounting
> hole, wind flowing over the back could generate some amount of lift, if
> there is some way for the wind to flow passed/under the root of the other
> blades.
>
Obviously, you have not read all my posts in this thread. Else you
would have read where I describe my device with blades designed to take
advantage of the lift effect.

.

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