> > > > > > Ken Welter wrote:
> > >> > >
> > >> > > The Ross gearbox that I had was a 3.17 to 1 and I don't think
they
> > >> > > were the same gear set as the 2.17 to 1 but cant be for sure.
> > >> > > That was the best ratio that I have run, much better than the
2.95
> > >> > > that I am currently running but its not practical get any lower
with
> > >> > > the cog belts I am running.
> > >> > >
> > >> > > Ken Welter
>
>
> > >> > The 2.17 takes the power from the ring gear. I think if you take
the
> > >> > power from the planet carries and hold the ring gear fixed you
> > >> > will get 3.17 out of the same planet set. This is also how the
> > >> > 2.85:1 works but that is an entirely different planet set.
> > >> >
> > >> > The one on the left is the 2.17 planet carrier and the one on the
> > >> > right is the 2.85 planet carrier. The sun gear shown fits both.
> > >> > So the sun gear diameter is smaller for the 2.17 giving a greater
> > >> > reduction when power is removed from the planet carrier.
> > >> >
> > >> > Paul Lamar
>
>
> > >> Ken could you give us a brief description of your setup and results.
What is
> > >> your cruise, climb and max rpm? What engine mods from stock have you
done
> > >> (i.e. oil pressure, rotor weight/balance, etc). I gather from other
posts
> > >> you use NOX. How long is the NOX on and at what rpm. How many hours
on
> > >> engine and any other comments on rpm? Also why did you prefer the
3.17 to
> > >> the 2.95?
> > >>
> > >> Thanks
> > >> Graydon Woods
>
> Ken Welter wrote:
> >
> > My plane is a slow boat compared to most of you, it only cruises at
> > about 110 mph but I takeoff at a gross weight up to 3100 lbs.
> > The engine that I am running 86 13b e-shaft and rotors with the
> > rotors cut for 3mm seals, 85 GSELE rotor housings and 12a side
> > housings and uses a Weber carb.
> > The nitrous is only used for about 5 to 10 seconds to lift it on the
> > step and get it out of the water.
> > I run the engine up to 7000 to 7500 rpm on takeoff, climb out at
> > 6500 to 6800 and cruise at 6000 to 6500 rpm.
> > The most I have put on one engine in the 1000 hrs on the old coot
> > is about 400 hrs, had lots of engine failures with that ross gearbox
> > but doing good now.
> > The reason I like the low ratio is if you run a 2 to 1 ratio you
> > double the torque to the prop and a 3 to 1 you triple the torque and
> > it takes torque to get static thrust and the more torque the bigger
> > the prop you can swing to develop the thrust.
> > Now I admit that torque and thrust are not everything if you want to
> > go fast but to lift gross weight especially out of the water its
> > everything.
> > Check out my web site and there are some photos of my old coot that
> > burned up a year ago, the new four place one is do to fly any day now.
> >
> > I looked at some old photos of my 3.17 ross and it does look like the
> > 2.17 is the same gear set.
> >
> > Ken welter
> > http://homepage.mac.com/rotarycoot/
Thanks Ken, great info. Exactly what I wanted. Beautiful pictures of your
coot on the water. As it snows heavily outside I can only dream of such
thing right now :) Keep us updated on the new plane.
Graydon Woods
Aren't those pictures great? I can verify it is as much fun as it looks.
Paul Lamar
I don't recall the final approach photos before, check out the RPM
on the tack, 5000 and we are dropping out of the sky.
Ken Welter
I have a bunch more that I have not uploaded. Not all are that good.
Paul Lamar
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