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Speed,Combat,Scale,Racing => Speed Talk => Topic started by: Skip Chernoff on April 23, 2018, 05:03:59 AM
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After fitting 5-40 bolts to the OS MaxIII and cutting a new base gasket I finally resolved the issue of the head coming loose. I filled the tank(2oz) to see how many laps she would do with the new .281 venturi. I did 40 laps. The next flight I took off did about 3 laps then went inverted. Winds were pretty steady around 13mph. On my 3rd lap inverted the engine suddenly quit. I should have landed her inverted,but decided to flip her over to upright thinking I had enough momentum. I was wrong. The wind got her,blew her into a funny position,lines went slack.The plane went straight in from about 30 ft. I thought it would be destroyed,but the only real damage was to the outboard wing panel where the weight box came thru the leading edge. I'll fix her today.But.....why did I have a fuel delivery issue inverted??? PhillySkip
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I repaired the plane and found out that on this set up the uniflow vent needed to be open to the air and the overflow vent needed to be capped off. I had it backwards when I crashed.Tank position was fine.
Anyway, she flew great today and I got clocked at 24.6 secs. for seven laps. Flying inverted at that speed is not an easy task. I got dizzy and almost fell down.
The plane is flying very nicely now. I'll play with props and slightly larger venturi.
One other thing, I discovered that this engine runs better with more oil in the fuel. I went from 20% half syn/half castor to 25% full castor.
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Good/Smart move on the fuel Skip! TS
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I give the credit to Joe Adamusko on the fuel suggestion. In a pm to you I said 29% it was 25%....Sig "Fox" fuel actually
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9x6 APC.....will experiment with others
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Thanks MM. I've got a bunch of the old Rev Up Pylon props from 8.75x 7 thru 9 x7.5. They are the ones with the thin blades .Any chance something in there might work as well?
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I'll try them out and report back.