Altimeter in Midpower rockets

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Jul 25, 2009
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I've built and flown a bunch of mid-power rockets but have never messed with the idea of adding a bay for an altimeter. That means I have questions. :) First of all does the nosecone attach permanently to the payload section? How do I design the payload bay to allow me to retrieve the altimeter? Your suggestions are appreciated. If you have a Rocksim file that would be awesome.
You are going to get a hundred and one different answers and suggestions to this one. so here's mine. you can buy little plastic rivet type pins that hold the nose cone to the body tube. or a cheaper, easier but uglier option is to use stardard bolts. that allows you to remove the nosecone and get access to the ebay. most people build a sled inside the ebay, where the altimeter is attached to a board, so this it is secure but can be removed for a different rocket.
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As Gillard said, there are lots of ways to do it.

I normally build my bays in the middle of the rocket, inside of a coupler. The drogue parachute is below the bay, and the main is above.

Is this for dual deployment, or just altitude measurement? If it is a simple non-dual deploy altimeter like the quest how high, I put it in a Bt 20 size tube then tape it in the payload, and put the nosecone on with a very tight friction fit.
This is for altitude only. I appreciate all the comments. Keep them coming.
This is for altitude only. I appreciate all the comments. Keep them coming.

Put it inside the payload bay. If the altimeter is a lot smaller than the diameter of the bay, glue a smaller tube to one side of the bay, then slip the altimeter in there and seal the top of it via a bulkhead that's held in place by a screw. Then, hold the nosecone on via plastic rivets or screws, and voila!

Here's how the TARC team I mentor is doing it. The rocket is BT-18 (2.56"). The altimeter is in the coupler for the payload section. The coupler has a solid bulkhead on the bottom which has a Bt-50 engine block in the middle of it and a BT-50 centering ring on top. A length of BT-50 with a couple of 1/4" square holes cut into the sides is glued between the bulkhead and centering ring. The coupler is slipped into the payload section tube and small screws (or the rivits other have mentioned) hold it in place. three 1/8" holes are drilled through the airframe and coupler so that they penetrate into the region between the bulkhead and centering ring. The altimeter is placed into the BT-50 tube with a bulkhead taped over the front end to seal it from the egg compartment. Actually, tape alone would probably work. They have flown it turning the altimeter (Perfectflite) on by inserting a jumper plug and with a switch installed on top of the coupler. Having a switch allows making three flights without having to take off the coupler to pull the altimeter since it will store 3 flights in memory. The switch was recessed and was turned on with a small screwdriver. The nose cone was taped on with Monokote trim sheet. They wrapped a 1" strip of chrome around the front of the payload tube and another on the back of the nose cone so the Monokote strip used to tape the nose cone on would not pull off paint. At the field, the egg was installed and the nose cone was taped on with another strip of 1" Monokote overlapping the ones on the payload section and nose cone.