Deployment Using Plugged Motors

I'm thinking of building a model with 4 A-10-P motors. I'd like to set an altitude record for that particular cluster. What would I need installed in order to fire an ejection charge to recover the flight? I'm thinking about using a BT-55 or BT-56 body tube

You need a deployment altimeter and a bay to put it in. You could build a bay into your nose cone shoulder, or create a bay using a coupler and bulkheads.

All kinds of deployment altimeters out there. Simplest and cheapest (that I know of) is the Adept DDC22 (about $25 plus shipping).

You will also need wiring, something to contain your charges, black powder, an ignition device (usually an electric match), battery (9V may be too big, consider LiPo), and static vent holes for pressure sensing.

I am not up on my BT sizes, so someone else may have more specifics as to what fits. AMW sells the Pico deployment altimeter, which is very small.

BigRiJoe said:

I'm thinking of building a model with 4 A-10-P motors. I'd like to set an altitude record for that particular cluster. What would I need installed in order to fire an ejection charge to recover the flight? I'm thinking about using a BT-55 or BT-56 body tube

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Frankly BigRIJoe, there is no way in hell you'd ever get anywhere close to setting any kind of altitude record with a cluster of 4- A10-PT motors. They are by themselves Altitude limiting being much heavier then 4- A10-3T which already have ejection charges which would eliminate your need for an alternative recovery system deployment system, Adding even more mass with the required timer, Altimeter, Battteries and such. Not to mention the absurd Frontal Area of a BT-55 or 56 airframe.

Cluster Altitude is one of the many NAR Contest events that has interested me for Decades. Over more then 13 years I've recently completed a Tech Tip covering all current Cluster Altitude events by motor classification 2x1/8A through 6xC.
Just so you know what your up against; 4xA cluster Altitude was recently flown at NARAM-47 out in Colorado.
The winning flight tracked and closed at 480m (1,574 ft).

If you like to investigate what is envolved in actural Cluster Altitiude model building may I suggest making a visit to www.narhams.org website. from the left hand menu go to the Library section, Open the Tech Tip folder and download Tech Tip-013 Cluster Altitude. This is a 33pg, 13year history of all 7 current motor class events, drawings and support documents on the how and why's of Cluster Altitude competition. I'm sure it will be of great usefulness.