Cl(VII)
Chris Bender
That is so impressive. Thanks for sharing.
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Upgrade NowIt seems, to me, that Eastern Europe countries have less restriction on motor impulse than Western Europe ?
Thanks guys. I was very surprised on the difference between altitude reading on Stratologger and ARTS2. GPS altitude and Stratologger altitude are preety close
(196 feet difference), but ARTS2 seems to be way off (1298 feet higher then Stratologger). It seems that Stratologger should be much more accurate with it's better baro sensor and 24 bit ADC compared to 10 bit ADC on ARTS2. Is this known issue with ARTS2 or was my unit not calibrated very well?
The 1300 feet difference at this altitude equals roughly to a difference of 20mBar air pressure. A 10bit ADC on an absolute pressure sensor with about 1050mBar range has an resolution of about 1mBar (~65ft resolution @ 23kft). The ADC alone (unless it is a horrible one with 20 LSB nonlinearity) wouldn't explain the difference. The classic Freescale sensors like the MPX4100A have an accuracy of 1,8% over the temperature range from 0°C-85°C. This alone would be nearly enough to explain the difference. In addition to that, there are many other sources for error. One notable difference, between the newer sensors from Meas Spec (probably an MS5607 on the Stratologger) is the calibration and compensation. The newer sensor offers a temperature readout and some calibration parameters (determined in the factory for each sensor) that allows the computation of a compensated pressure value that will be much more precise. The hardware temperature compensation in something like the MPX4100A works in a much simpler way and therefore is less accurate.
Finally, even the GPS system and the Stratologger have only a limited accuracy. The Stratologger uses an atmospheric model that does not exactly reflect the atmospheric conditions on your launch site. GPS on the other hand is less accurate in the vertical direction compared to the horizontal direction, because most of the visible GPS satellites are rather close to the horizon. All of the affordable (and unregulated) GPS systems are optimized for a different dynamic environment (cars, pedestrians). This will also limit the accuracy when used in rockets. Seeing that GPS and the Stratologger agree within less than 1% is quite good in my opinion, but you might have been lucky on this flight.
Reinhard
It seems, to me, that Eastern Europe countries have less restriction on motor impulse than Western Europe ?
out of curiosity, why all aluminum ? 1.9mach doesnt require it. CF or FG would be much lighter.
Im new to rocketry so this may be a basic question but are you not taking a risk by using one chute ?
Some detailed pics of the internal workings would be great.
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