OS 91FX

[Ihncheol Park]

Nat,

What are the differences between running the 17x10N cut down to 16" and
normal 16x10?
Also, from a pro_performance spreadsheet which I downloaded from a website.
Thrust = 2.83E-12 x RPM^2 x D^4

15x8 @ 10K rpm (actually running rpm): 15.9 pound of thrust show up.
17x10 @7800 : 15.96 pound
16x10 @8000 : 13.18 pound

Not really sure if the equation is meaningful at the actual running.
Are you using the larger diameter prop to reduce noise?
I also heard you were using 91SX-H.

Ihncheol Park

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Nat Penton
Sent: Saturday, October 25, 2003 10:25 PM
To: discussion at nsrca.org
Subject: Re: OS 91FX


Matt I will add additional  info. Have been running the 91FX over two years
and it will carry my 8+ lb airplanes to the moon. On fuel - was using
Ritches 20%, now 30%,idles under 1500. Pipe length- 26 to 28" depending on
which pipe, most power from ES 2 stk(1 9/16 OD), Favorite props 17X10N cut
to16" and 15.5X12, rpms around 7700. Using Hanno (same as 140RX) backplate
pump. Can be installed with simple tools and a little ingenuity. O yes 2
headshims. Stock bearings good for about 30 flts, Boca sealed well over 100,
leave all seals in place. Provide crankcase cooling for longer bearing life.
Have not tried 15CC Hatori or MACS but plan to. Headers are from Karl
Mueller,very nice.
----- Original Message -----
From: "David Gundling" <DGundling at compuserve.com>
To: <discussion at nsrca.org>
Sent: Saturday, October 25, 2003 8:34 AM
Subject: Re: OS 91FX


> Message text written by INTERNET:discussion at nsrca.org
> >The 91 FX is stronger than the ys 91 4 cycle with some margin. Stretch
the
>
> pipe a bit with an extra long header and run the larger prop. The set-up
> will
> amaze you with its output and quietness. Good friend Nat is using it on
his
>
> X-Press turning a 17x10 N cut down 1/2 inch. Plenty of power for the 8-9
> pound
> plane.
>
> Matt K<
>
> Matt,
>
> Thanks.
>
> Dave
> # To be removed from this list, send a message to
> # discussion-request at nsrca.org
> # and put leave discussion on the first line of the body.
> #
>
>
>

=====================================
# To be removed from this list, send a message to
# discussion-request at nsrca.org
# and put leave discussion on the first line of the body.
#


=====================================
# To be removed from this list, send a message to 
# discussion-request at nsrca.org
# and put leave discussion on the first line of the body.
#