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Originally Posted by Doug G
Just to help clarify Salik's post...
Team America Rocketry Challenge is the contest we've registered for, which requires a rocket, no more than 1.5 kg, to loft one egg to 800 ft and return it safely in a total elapsed time of 45 seconds.
Yes, many teams simply design their rocket around a certain size and motor and then ballast it to get it to the right altitude. We do have RockSim as well as a computer model done by scratch using Excel, engine thrust data, and our physical rocket characteristics (mass, drag coefficient, etc..).
But in an attempt to be a little more "high-tech", the students wish to add on-board controller to monitor altitude (barometric pressure) and then activate a servo to release a "spring loaded" nose cone and a parachute as well. In this case the engine would not include the ejection charge or delay - an option they have because they're using a reloadable motor system (Aerotech)
There are commercial altimeters available for model rockets - but they're meant to trigger (relay?) a black powder charge to "blow-out" the nose cone and/or drone chute. The rules of the contest do not allow for separate ejection charges. Which is why they are trying to design their own "altimeter" and non-pryotechnic ejection system.
I suspect if they cannot get their "altimeter" to work, they will just use a standard engine with a normal ejection charge as a fall back approach.
Unfortunately I have very limited knowledge of circuits and programming, but Salik is very familiar with programming the FIRST/IFI/Microchip Robot Controller.
The best type of controller (and possibly programmer) to use is what our team needs help with. We appreciate the help and welcome more ideas or comments.
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Hmm, so it looks to me you don't really need to ever use the altitude, you just want to eject at altitude X. I would look for a sensor that can be set to either allow current to flow, or current to not flow, at a preset height. That would make it much simpler and cheaper. KISS.
But, yeah, I don't know if those types of sensors exist.
