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mikemech
03-22-2013, 02:30 PM
What am I doing wrong?

I'm preparing for my L1 attempt with an Estes Ventris. First time with RMS motors. The ship is built according to factory instructions except for a metal tube for the kevlar shock cord. When I sim (RocSim) with a H55W I get strange accelerations.

H55W-10 15g
H55W-14 50g

H = Total impulse
55 = average thrust
W = White Lightning
10/14 = Ejection delay

Am I reading these correctly? I don't understand how a delay change could affect acceleration. If anything a longer delay should reduce acceleration slightly from a heavier motor.

Thanks,
Mike

Doug Sams
03-22-2013, 03:48 PM
What am I doing wrong?

(snip)

H55W-10 15g
H55W-14 50g

(snip)

I don't understand how a delay change could affect acceleration. The max acceleration detection includes the ejection event - ie, it includes all accelerations during the flight including the post-burnout data. With the longer delay, you will get a very hard jerk when the chute opens, and that event imparts the greatest G's during the flight profile. Thus, it is detected as the max-G event.

Try stopping the sim at motor burnout. You will then be able to see the max-G value due to the motor's thrust without the deployment event affecting it.

Doug

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ghrocketman
03-22-2013, 03:52 PM
+1 to what Doug just said.