Excelleron with OS 91FX in Intermediate ?

[Eddie Batchelor]

Paul
I flew mine initially with a YS91AC. Although it flew fine for Sportsman, I
don't think it would have the power you need for intermediate. I switched to
a Ys110FX

Now if you decide to use the OS91FX - pipe it according to Nat Penton's
instructions and prop it with a 15X10 or 15.5X11, you'll have all the
vertical you could wish for. But this would require some surgery to the fuse
for a pipe tunnel.

BTW with the OS91/header/ESpipe and Bolly gear you should be under 8 pounds.

I'm including a coy of Nat's instructions in case you missed them :

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Nat Penton
Sent: Sunday, December 12, 2004 2:39 PM
To: discussion at nsrca.org
Subject: [SPAM] 91FX
I have forgotten my pipe length, 24/25ins , ES ( 1 9/16od x 26oal ). The
choice of pipe does make a difference. My favorite prop is the 14.5 x 11,
4bl, year around. Will occasionally run the 15.5 x 12, 2bl in windy
conditions. Yesterday I ran the 16 x 11 cut to 14.5 ", with the tips left
square. Surprisingly it was at least as quiet as the 4bl and perfomed very
well. You sure can't judge by looking how noisy they are going to be. I want
to get a 16 x 10 and cut it back to 14 3/4 , plus or minus, for a try

and :

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Nat Penton
Sent: Sunday, December 12, 2004 6:32 PM
To: discussion at nsrca.org
Subject: 91FX
I rarely check rpm but know I am turning in the 76 - 7800 range. Strong
vertical, 8# airplane. 30% nitro, two shims. Choice of pipe can make a
significant difference.

I  feel that I am losing little if any thrust horsepower with this setup.
The larger props are more efficient and I am running lower tip speeds which
further improves the efficiency, and it is quieter.

I must have a thousand flights on this piston and liner. Am pleasantly
pleased they hold up so well. Also the SS sealed bearings are a blessing.


Eddie

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Paul Horan
Sent: Tuesday, December 21, 2004 9:10 AM
To: discussion at nsrca.org
Subject: Excelleron with OS 91FX in Intermediate ?


    I received my Excelleron but am wondering about what engine to put on
it.  I
Have a OS 91FX and a YS 91AC.  My concern is having enough power for
the vertical maneuvers in Intermediate, particularly the 1/2 square with 1/2
roll
and the stall turn with full roll.
    Any suggestions ?
Thanks
Paul Horan
KC5NF
AMA 57131
NSRCA 3606
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