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Author Topic: Damaged My Sportsman Speed Ship  (Read 1480 times)

Offline Skip Chernoff

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Damaged My Sportsman Speed Ship
« on: April 23, 2018, 05:03:59 AM »
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

Offline Skip Chernoff

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Re: Damaged My Sportsman Speed Ship
« Reply #1 on: April 23, 2018, 07:38:55 PM »
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.

Offline C.T. Schaefer

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Re: Damaged My Sportsman Speed Ship
« Reply #2 on: April 24, 2018, 06:07:35 AM »
Good/Smart move on the fuel Skip!    TS

Offline Skip Chernoff

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Re: Damaged My Sportsman Speed Ship
« Reply #3 on: April 24, 2018, 06:07:06 PM »
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

Offline Skip Chernoff

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Re: Damaged My Sportsman Speed Ship
« Reply #4 on: April 25, 2018, 03:04:15 PM »
9x6 APC.....will experiment with others

Offline Skip Chernoff

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Re: Damaged My Sportsman Speed Ship
« Reply #5 on: April 26, 2018, 05:03:20 AM »
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?

Offline Skip Chernoff

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Re: Damaged My Sportsman Speed Ship
« Reply #6 on: April 27, 2018, 07:17:34 PM »
I'll try them out and report back.


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