Timer or Altimeter ?

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Well-Known Member
Apr 28, 2004
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I was wondering what you guys thought regarding the pro's and con's of using either a timer or altimeter. I know I can build a timer for about $10. Altimeter kits are more expensive and complicated. I am just trying to determine what the best route is.


It depends on your purpose. If you want it for staging, go with a timer, since most motors are based on time-of-burn. If you want it for a delayed deployment of a main chute, go with an altimeter (drogue at apogee, main at 500 ft AGL). If you want apogee ejection, you can use either, but it's risky either way, as your simulations will be critical. Timers may not get the apogee right, and you could eject early or late. Altimeter may be set too high (or your rocket may not fly straight up!) and never deploy, or set too low and it deploys early (can you say "super-zipper"?). Magnetic apogee detection systems are designed for this purpose, but everything I've heard about them is that they are somewhat spotty in their reliability.

You make the call.


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