Jett Engineering Sport Jett 50
08-19-2008, 12:14 AM
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Jett Engineering Sport Jett 50
today was my second session for breaking in my sj50...coolpower15%, 9x7apc...17,400 (i haven't found the peak yet)...richened it to 17,040, and varied throttle between idle, midrange, and wot...fantastic engine...btw, i calibrated my tach on the fluorescent fixture over my workbench (3,600), and the tv set (1,800)...ken
08-23-2008, 05:55 PM
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RE: Jett Engineering Sport Jett 50
i ran my sj50 this morning on cool power 12.5% heli fuel (17% ultra-high viscosity syn lube), and as jett engineering/bob27s recommended, w/ a 9x6 apc...i'm closer to finding the peak - 18,330...i richened it to 17,300 to finish the break-in...needless to say, i'm very impressed with the engine...when the engine was hot, the compression was perfect...when the engine cooled down, the pinch was still very, very tight, and i had to caution my buddies when they tried to finger-flip the prop...now i just have to finish the airframe (waiting on new servos)...ken
08-23-2008, 11:35 PM
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RE: Jett Engineering Sport Jett 50
ORIGINAL: rainedave
Cool. FYI, APC's safety limit for 9" props is 21,111rpm.
[190,000/diameter]
David
Cool. FYI, APC's safety limit for 9" props is 21,111rpm.
[190,000/diameter]David
09-24-2008, 02:03 PM
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RE: Jett Engineering Sport Jett 50
The sport jett version muffler tuning tends to drop off around 18,500 - its not going to unload much above 19K in flight - tends to work like a governor.
You are just fine with the 9x7 ........ but you probably would want to avoid flying with the 9x6.
Sounds like it is running well. Use the 9x7 for a few flights.... then move to a 9x8 or a 10x6 depending on what you want for level flight speed.
