[NSRCA-discussion] OS-120AX questions/thoughts... yes again

[ronlock at comcast.net]

29% castor - sounds like CL stunt fuel.  Does it get tail heavy during flight?  <G> 

I'd suspect some of problem will go away when you switch to more typical pattern fuel mixtures. 



Couldn't hurt to move tank down to on carb centerline. 



Ive had excellent results for years with DuBro sintered brass fuel line clunk.  Maybe YS foam clunk would be as good? 



Ron Lockhart 


----- Original Message ----- 
From: "J Shu" <jshulman at cfl.rr.com> 
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org> 
Sent: Sunday, September 20, 2009 4:43:02 PM GMT -05:00 US/Canada Eastern 
Subject: [NSRCA-discussion] OS-120AX questions/thoughts... yes again 

Hi All, 

I've posted in RCU about some issues I'm having with my OS-120AX and was wondering what you might think? 

Here's the the link: http://www.rcuniverse.com/forum/m_9110170/tm.htm 

And what it says: 

I'm hoping this thread will help answer some questions about the OS-120AX that I am having. 

I've got it in an 8lb 2oz, 110 sized pattern plane, stock muffler, 420cc tank (14oz), OS-F plug, 3-line system (Vent, carb clunk 
line, fill clunk line), 15x10 APC and for break-in, PowerMaster 10% with 29% Caster... will switch to 15% with 16-18% Synthetic 
after this gallon. 

The tank is fairly close to inline with the carb, maybe 1/2" higher. On neg/inverted pushes the motor seems to starve until I close 
the throttle a little. On pos/upright pulls it seems ok, maybe a slight richening. There is a nice smoke trail as after my first 
flight I wasn't rich enough and the flight ended a bit early. I'm sure it will run a bit easier after it's broken in, but has anyone 
tried a foam clunk like the YS's use? 

Any other tips? It has enough power with this set-up to go through the F-09 sequence, but about half way through it starts this 
'cutting out' deal. It's just annoying to have to power back as you're climbing to keep it running. 

Also, what differences has anyone noticed flying the 15x10 to 16x8 in testing. 

Regards, 
Jason 
www.shulmanaviation.com 
www.composite-arf.com 

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