Another student pm'd me with a very similar description, so I will answer here to benefit many.CypherKat wrote: ↑March 12th, 2023, 6:59 am https://drive.google.com/file/d/1BSGzer ... sp=sharing
https://drive.google.com/file/d/1uvC9tf ... sp=sharing
https://drive.google.com/file/d/1p-bK2U ... sp=sharing
hello! I am back after a round of test in my school gym.
For each of these flights we got the rubber to 100 winds, and dewinded 5 turns on the winder, we don't have a torque meter sadly so I cant speak for that. We used the same rubber on these which later snapped, but it came in on 1.90 g and around .63 g/in. we messed around on CG placement but I wanted some tips on hitting the 2:30 mark. States is this Thursday, so we'll try ot get one final testing in before comp.
Thanks
The issue they reported was that they got to 12 consecutive flights and rubber finally broke, but no torque meter. It appeared, as I am inferring here, that students are winding the same number of wind and unwind on a single price of rubber and expecting the same results. That does not happen. Up to a point, perhaps 6 flights or so, each wind will break in the rubber more, be and if you wind to the same torque you will get considerably more winds. Winding same number of winds will result in much reduced torque, and thus less climb and disappointing letdown. After that the rubber may get tired and start to lose performance, up until it breaks. If winding hard, we rarely see much more than 6 uses of a motor.
The only way to get consistency in performance would be with a torque meter. A simple wire one is available from J&H for $14. I believe Ray Harlan's site may have instructions on making your own.
The only other way to get predictable performance, though not necessarily optimum, would be to track flights and winds each flight on the motor, be and then make identical motors with identical wind history for your event. Probably easier to just make a torque meter.
Coach Chuck