> > > George,
> > > I think you missed one point, my single rotor is based on 12A
parts. I
> > > extrapolated to 13B you are looking at around 150hp at 7500RPM.
> > >
> > > Richard Sohn
> > > N2071U
> > >
> >
> > I guess I've also missed some of the info provided by Richard and Paul,
> > I'll go back and check. While Richard's work on the single rotor was
> > interesting, I'd figured I would need a two rotor to provide enough
> > power for the Vision acft. But, that plane is limited to 300 lbs FWF,
> > so it is right on the borderline for using a 13B (if we include the
> > PSRU, engine, mounts, cooling plumbing, etc). Now, if we could get
> > 150HP reliably from a single rotor, that might be just the ticket.
> >
> > Last time I looked at it, the incremental weight savings from
> > eliminating one rotor didn't seem to be worth it for this application
> > (given the development work required and the potential for decreased
> > smoothness and reduced redundancy). Maybe I need to keep an open mind
> > about the potential for using a single rotor 13B as Richard
continues to
> > open these doors.
> >
> > Mark Waldron
>
> Mark,
> My single development is designed for the Vision aircraft, Steve suggests
> best power is between 115 and 125 HP. Weight will be under the 300 lb FF
> limit for the single.
> You could use a 2 rotor in a Vision and move the wings forward, Steve
> suggested some time ago a 400 FF limit would require 4" forward travel of
> the spar ( approx). All design changes should be approved by the
designer.
> You could also use some weight in the tail of the plane, because of the
> fulcrum effect the weight would be much less than the extra FF weight.
> Some are planning 2 rotor installations.
> George ( down under)

George,
I'm glad you are still going with the Vision, and with the single rotor
development.  I was thinking we could get the weight/balance in line by
going with radiators (oil and water) mounted aft of the CG.   I had
thought the 300 lb FWF limit was a function of the limit of the
spar/fuselage shear web (?) design strength, not CG.  I'm probably
misremembering it.

I want to be able to safely fly at the heavy side of the envelope
(approx 1800 lbs GW, with slotted flaps and the long wing).

Regarding moving the wing forward:  Any variation from plans introduces
complexity/delay, but it might be worth it if the alternative is
insufficient nose-up trim ability.   I'd do it if I couldn't get a
satisfactory result with battery/radiator placement.   Plus, it will
give an excuse (since I'm already "off the reservation") to explore
removable wings.  Thus the spiral of complexity widens . . .

What do you believe your single rotor engine will weigh?

Mark Waldron