Eggtimer Rocketry Flight Computer Uživatelský manuál stáhnout pdf (Strana 33)

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You can clearly see that the rocket hits peak altitude at about 10 seconds, and maximum velocity at

about 3 seconds. Note that the velocity graph is jaggedy compared to the altitude graph; this is due

to the aforementioned issues with deriving velocity from barometric pressure. The important thing

is that you can see clearly where the velocity peaks then drops sharply; this is where the motor

burned out and aero drag immediately started to slow the rocket. You can also see where the

motor’s ejection charge fired about a second after apogee (the 7 second delay was a good fit), and

the rocket starts to slow. In this case, the drogue chute took a few seconds to open up, so you see

that the rocket descended about 300 feet in 8 seconds, then slowed as the drogue chute opened up,

then slowed even more at around 75 seconds at a little under 300 feet as the main chute opened. The

last 250 feet or so took nearly a minute; obviously both the drogue and the main chute were too big,

but this was a very conservative build. If you look at the velocity graph, you will see disturbances

where the ejection charges fire; this is because the jerk of the parachute coming out causes a short

pressure “bounce”.

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Eggtimer Rocketry Flight Computer Uživatelský manuál Strana 33