04-03-2019, 09:43 PM
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Master Modeler
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Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 6,507
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Quote:
Originally Posted by teflonrocketry1
I created a RockSim flight simulation for the Mini-Comanche 3 visit:
https://forums.rocketshoppe.com/sho...453&postcount=3
I have been looking at the length of the launch guide and even when I set the length to only 27 inches the rocket reaches 35mph at the tip of the launch rod with a stability margin of 8.24 calibers for the 3 stage configuration. Based on the simulations I would say the problem could have been due to a wind gust, as the large surface area of the fins and over stable design would allow for a horizontal flight path if there was a gust of wind at the moment of the launch. Another possibility would be launch rod whip. What was the launch rod made of? Carbon steel rod is more prone to rod whip than 316 stainless steel. You also cannot rule out launch lug binding which would easily cause a slow speed at the top of the launch rod. Did you wipe off the launch rod before your flight?
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The standard aluminum 1/8" launch rods are "whip-resistant," too, unlike steel ones (G. Harry Stine tested both types and measured it).
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