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95 AX, "mr. deadstick"

Old 03-10-2014, 01:33 PM
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Tony Iannucelli
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Default 95 AX, "mr. deadstick"

Hi Bill. I'm a long time OS guy. No multi cylinders, but most of the others. My 95 AX has me stumped. Same issues many guys have had in the past. Runs great for 3-4 minutes, then quits. My Aeroworks Yak 54 (60 size) quits on the vertical line which has proved to be fortunate -- I always seem to have plenty of time to land. My first thought was too lean, crapping out because of the nose-up attitude, but I don't think so.

I use 20/20 fuel, OS8, 15-6 APC, get good smoke. The 15-6 is 'up' from a 14-8 which I thought might not have been loading the engine properly. It's fresh fuel. I run 20/20 in everything, mainly 91-95 four strokes, and they eat it up. Also helis, 50-70 size mostly. Should I drop down to a 14-6/10 to see if it helps?

The tank seems good but just to be sure I changed the lines. I'm using 1/8" brass, heavy clunk, carb line is as short as possible. The muffler is untouched, that is, the baffle is in there.

Can't imagine it needs a shim because no other engine I have, using the same fuel, ever required it. I'll get a gallon of 10-15% instead of my 20/20 if you think that will matter. By the way, great idle, about two turns open on the main, at half throttle it sounds like an engine "coming on the pipe" like in the old days. Any plausibility to switching to an OSF plug in your opinion? Should I use two washers with the F plug? This engine has too much power to be sitting on a shelf, and me with a long face and out $250. Thanks for your help. --Tony Iannucelli

Last edited by Tony Iannucelli; 03-11-2014 at 04:32 AM.
Old 03-11-2014, 06:26 AM
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Bax
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We always wonder at the large propellers for modern glow engines. We seem to find they run better when you allow them to turn up a bit. The 14 x 8 should be a good starting point. Get that engine much below 10,000 RPM and we're not surprised you have difficulties. Also, you may not get enough pressure to the fuel tank to get good fuel flow in the verticals. If it always quits in the verticals, then we'd suspect fuel flow. You can try going to larger fuel lines (don't forget to drill-out the clunk) to get a more-free flowing fuel system.

In the "old" days, we'd put a 13 x 7 or 8 on a .90-size engine and turn it near 12,000 RPM. The .91 FX did best near there, but it was noisier. Large props work well for noise reduction, but not so much for power and handling. O.S. rates the peak power at 15,000 RPM, so peak torque is going to be near 12,000 or so. You should be able to prop it to run above 10K and get good power and handling.
Old 03-11-2014, 08:18 AM
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Tony Iannucelli
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Thanks for the reply Bill. I've put the 14-8 on there already, and will get to fly it again in a couple of days. My concern now is carrying too much speed on final with 30% more pitch because the airframe is pretty slick. I hope it idles as well as it did with the 15" prop.

My last resort is to put my 95 four stroke in there instead. That one is a brute, and handles just beautifully. Pulls vertical all day long.

I remember putting a 13/8 on my 91FX at your recommendation. Hope the 14/8 works as well on the 95AX.

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