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Old 26th August 2016, 06:04 PM
Nomads HFT Nomads HFT is offline
Join Date: Sep 2015
Location: Worcester
Posts: 66

Today I tested one of my piston seals for friction at 20C and 46C.

At 20C, the static friction was 6.07N (Newtons), the kinetic (sliding) friction 4.38N

At 46C, the static friction was 10.6N, the kinetic friction 7.35N

I had a second seal in my TX cooking in the greenhouse, and when acclimatised to 46C, the muzzle velocity was the same as at 20C.

For comparison, Rob's unsized seal was nearer 23N at 40C (much higher), down to under 5N when sized.

Worth bearing in mind that the kinetic friction figures quoted exist only for a very short period of time at the very start of the stroke; when the cylinder air pressure increases, they rocket.
Nomads HFT
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