User`s manual

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will be 100 ms. You cannot change this setting, it is automatically populated when you change
the Bur/Coast Sample rate.
C Descent Samples/sec. <
<<
<1,
1,1,
1,2,4,5
2,4,52,4,5
2,4,5,
,,
,10
1010
10>
>>
>
This selects the number of samples per second that are written to flight memory after nose-over
is detected, until the rocket lands and sampling ends. Values are 1,2, 4, 5, and 10 samples per
second.
Nose-over is defined as one second after apogee, the maximum altitude. Since apogee can’t be
predicted ahead of time, it must be inferred after readings for altitude begin to drop. The
Eggtimer does this after one second of descending readings after the last maximum altitude
reading, on the theory that if that much time has passed then you’re not going any higher. Since
the rocket’s vertical component velocity at apogee is by definition zero, it will be moving
relatively slowly at nose-over, so if you choose to deploy a parachute at that time you won’t put
much strain on your recovery device or suffer the dreaded “zippered” body tube (unless your
rocket happens to be going horizontal, of course…)
Descent sampling rates can be very low, because the rocket is going to be descending very
slowly, typically under 50 ft/sec on a drogue parachute and 20 ft/sec on a main parachute. It
doesn’t make sense to waste memory by recording very small differences in altitude change. At
50 ft/sec, and a sample rate of 10 samples/sec, the rocket is only moving 5 feet per sample. If
you’re descending from 2,000 feet, that’s 400 samples that basically look alike, so it really
doesn’t produce a “better” graph by turning this up, and you will either waste a lot of memory or
you will run out of memory. A sampling rate of 2 samples/sec is adequate for most flights. In
fact, if you’re going over 5,000 feet then you should probably set it to 1 second since you
probably are going to be using a higher main deployment altitude with a higher altitude flight
anyway, and the difference in main deployment altitude will be minimal.
The Eggtimer will sample altitude at the descent sampling rate until either landing is detected, or
it runs out of memory for that flight. Landing is detected when altitude readings of under 30 feet
AGL are recorded for at least five seconds. After five seconds, the implication is that you must
be on the ground, so recording stops and the Eggtimer begins beeping out the apogee. You
normally will not run out of flight memory, even with a high-power rocket and higher sampling
rates; however, if you do it will only stop the recording of the altitude readings to flight memory,
it does NOT affect parachute deployment, so you may not even know that it happened until you
dump the data afterwards. If you are unlucky enough to have your rocket get stuck in a tree
higher than 30’, you almost certainly WILL run out of memory; however, it will have no effect
on the flight data other than showing you how high off the ground the rocket was when it got
stuck.
Descent Interval (ms.)
This is the amount of time, in milliseconds (1/1000 sec.) represented by the Descent Sample
setting. For example, if you set the Descent Sample setting to 2 samples/sec, each sample will be