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Full Version: Is a separate altimeter bay required ?
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Hi All,

   I am planning to use Firefly and MicroPeak altimeters for the altitude events at the coming NARAM 60.  My question concerns their mounting in the rockets for the various events.  Specifically, is a separate compartment required for all events or can I simply tie the altimeter to the shock cord?  I do not see anything in the current Pink Book about this.
   My A Payload models have vented separate compartments and, in C Eggloft, I am planning on putting the altimeters in the egg capsules which all have room in the molded shoulders that plug into the tube.  This would again serve as a separate compartment and again these are vented.  I suppose my question applies more directly to the C SR altitude and B Cluster altitude events.  I was going to simply hang the altimeters on the shock cord for these events and vent the body tubes.  I figure the wadding and recovery systems would provide enough protection from the ejection charge for the altimeter's safety.
   Since I am newly returned to rocketry competition after 15 years, I am a newbie to altitude competition utilizing altimeters and would greatly appreciate your comments and suggestions.

Mel Gray
Gray Matter Rocketry Team
If they are well protected from the ejection gases as you note, then they will be fine. My wife made little fleece pouches for my FireFlies (and one for a MicroPeak) that were inspired by the little ones DinoChutes sells for AltimeterOne/Two/Three that I have been using to good effect in models without dedicated payload compartments. You will probably want to put static ports in the body tubes anyway, however

One note - the MicroPeak is kind of touchy about sunlight shining on the sensor so you might want to wrap it in something dark and preferably mostly opaque if you are going to use one outside of a dedicated payload compartment (or in one, if it’s clear). The instructions for the Apogee Midge actually have you paint the inside of the transition (which is vacuum-formed thin white plastic) black if you’re flying a MicroPeak to protect against this light sensitivity.

The FireFly has a little black sticker over the sensor (and under the shrink wrap) to address this same issue. That seems to work OK.