[NSRCA-discussion] OS 91FX or 120 AX for Focus sport

[Bob Richards]

What are you guys using for muffler/pipe on the 120AX?
 
What you say makes sense if you look at ALL the numbers. The 2.8hp of the .91 is at 15k rpm, while the 1.20 is 3.1hp @ 9k rpm.  The hp of the .91 will probably be much less at a pattern useable rpm, while the rated rpm of the 1.20 is very close to a useable rpm figure.
 
Bob R

--- On Thu, 6/26/08, J N Hiller <jnhiller at earthlink.net> wrote:

From: J N Hiller <jnhiller at earthlink.net>
Subject: Re: [NSRCA-discussion] OS 91FX or 120 AX for Focus sport
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Thursday, June 26, 2008, 4:02 PM








I recommend the 1.20 AX. It will turn a bigger prop, which offers a more efficient HP – Thrust conversion. I am flying advanced with a 9+lb airplane powered with the 1.20 AX and a 16-10 APC. I am getting away with the 16-10 but I feel I am pushing the upper limit. It would probably be more comfortable with a 15-10 or 16-8. It is probably more power than needed in lower classes but throttle management is one of the things we need to learn and the sooner the better, besides the extra power will be most welcome in adverse weather conditions.
Jim Hiller  
 

 




 

120AX

91FX


Displacement (Cu in)

1.2

0.91


Weight (gr)

650

550


Output (BHP at RPM)

3.1 at 9000

2.8 at 15,000


Cost

250

200


 

 

 


output/ weight

0.004769

0.005090909


Output/ displacement

2.583333

3.076923077
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