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OS 1.20AX Tank Size

I'm debating between the OS 120 S-E four stroke or the 1.20AX. Looking at the on-line manuals for each, OS recommends a 400 CC (14 oz) tank for the four stroke for about 10 minutes flights and, oddly enough, a 350 CC (12 oz) tank for the 1.2 AX for 10 to 12 minutes flights. I always thought a 4 stroke burned less fuel than a 2 stroke. Does a 12 oz tank sound right for the AX? Is it possible that OS recommends the small tank for the AX due to fuel draw issues? What size tank do most of you use?

Thanks! Dick

Reply to
RC Trost
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ALWAYS use the largest tank you can comfortably fit into any model!! The size of the tank will not adversly affect fuel draw. It is possible that a taller tank may flow more easily due to increased hydrostatic head, but this effect would be minimal.

Fuel draw is governed primarily by intake venturi size, and in a fourstroke, intake timing; but not by tank size....

Cheers,

Bill

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Reply to
Bill Fulmer

I don't have a 1.20 AX, but that certainly sounds 'optimistic' to me.

A .46AX at full song is flat out delivering 12 minutes from a 10oz (320ml) tank, so unless you're beetling around the circuit at approach 'n idle power, the 1.20 AX wouldn't have a hope!

16ozs minimum for the 1.20 AX.....unless you enjoy short flights?
Reply to
CguLL

Thanks, everyone, for the input. 12 oz didn't sound right to me but I've never run anything larger than a 60, which typically took a 12 oz tank. It was hard to believe the same tank would be recommended for an engine twice a big. Maybe it's a misprint in the users manual although 350 CC is mentioned twice. Dick

Reply to
RC Trost

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