My best WRONG reading?

Post your team or personal best. To be displayed on the WRA2 standings page(Altimeter Data and Videos are optional)
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Braaainz
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Joined: Thu Jul 26, 2018 3:53 am

My best WRONG reading?

Post by Braaainz » Fri Sep 14, 2018 7:17 pm

I'm using a Jolly Logic Altimeter 2.
Altitude 376
49 mph top speed
1.40 thrust time
Peak acceleration 12.5 g's
Average acceleration 8.4g"s
Coast at apogee 3.6 seconds
Ejection 342
Duration 31.7
Descent 6
Apogee ejection

Does this look correct? I don't have a computer to run a simulator.
Seems way too high to me.



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anachronist
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Re: My best WRONG reading?

Post by anachronist » Wed Feb 06, 2019 12:30 am

I'd have replied sooner but for some reason all the WRA2 email notices were ending up in my spam folder, and I just noticed it now.

If you provided some additional information, I could run it on my simulator.
  • What is the total volume of the pressure vessel? (e.g. 2 liter bottle, whatever)
  • How much did you fill it?
  • How much air pressure did you pump into it?
  • What is the diameter of the nozzle?
  • What is the weight of the rocket before filling with water?
Quick and dirty calculation, assuming constant 8.4G acceleration for 1.4 sec:
8.4G = 8.4*9.8 = 82.3 m/s/s
v = a*t = 82.3 * 1.4 = 115.2 m/s = 257 mph, which is way off the top speed recorded.

I'm skeptical of that thrust time if it's a bottle, typically the thrust is over after about 0.1 sec, not 1.4 sec.
Need more info.
-Alex



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