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-   -   altitude predictor (http://www.oldrocketforum.com/showthread.php?t=5244)

jgonza 05-08-2009 08:04 PM

altitude predictor
 
I use mark sullivans altitude predictor to figure the flight characteristics for my rockets. The problem is the delay that is given is often a second or more too long. I build my rockets with aerodynamics in mind. no sloppy fillets and smooth paint why would the delay be so wrong. ex. 47mm body, 457.2 mm chute 353g liftoff weight with a f39-9 motor. the site i use gives 8.1 seconds from ignition to turnover, motor burns for 1.3 sec. so adelay of 6.8 should be appropriate, yet it falls for 1.1 seconds when i use a 7 sec delay, is the predictor innacurate or am i missing something?


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