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Old 06-14-2020, 12:17 AM
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BEC BEC is offline
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Join Date: Feb 2009
Location: Auburn, Washington
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Default Do old black powder motors really perform better than new ones? - a small test

In the “Any sign of the C5-x yet?” thread, the discussion at one point turned to the assertion that old motors actually perform better than new ones. I jumped in with both feet suggesting that I could at least take a small stab at figuring this out by doing some test flying in a model in which I have literally hundreds of altimeter-equipped flights (over four examples of the model) - the Nova Payloader.

Thanks to donations to my club and some binge buying when I first got back into rockets I had access to some old but apparently well stored motors. So on May 11th I took a Nova Payloader and an AlitmeterThree and 10 B6-4s up to Sixty Acres to do some flying. Three of them were dated 5 H 6 (June 5th, 1977), three of them dated 7 X 10 (October 7, 1993) and four of them dated H180119. I also took along a couple of B8-5s from 1995 and some Q-Jet B4-4s.

I proceeded to put a total of 14 flights on the model pretty much as fast as I could prep it, fly it, download the data from the A3, make some notes, and repeat. Ten of them were on the B6-4s listed above. I mixed up the ages of the motors in the flight sequence to try to minimize the effects of the weather. Before the last B6-4 flight I flew one of the B8-5s just for amusement sake, then flew three Q-Jet B4-4s to compare (and see how consistent they were).

The one impression I was most left with was that the recent motors (all from the same bulk box) are more inconsistent than the older ones. Both the highest and lowest altitudes of the 10 B6-4 flights were on the 2019 motors.

So....here’s the data from those flights plus four more a few days later.

All of these are on the same model the last one (flight 50) had such a wimpy ejection charge the ‘chute didn’t come out (and the A3 didn’t detect an ejection). It streamlined in the last 100 feet...so needed some extensive rebuilding afterward .
Attached Files
File Type: pdf NovaPayloader(4)-5-12-20_flights.pdf (134.2 KB, 60 views)
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