I have built my first HPR rocket. I haven't certified yet. I am going totry in April. I am most likely going to go with basic motor ejection. I dohave a flight computer but I do not want to complicate things for my firstflight.My question is what options are there for parachute ejection... With amotor charge the blast direction is towards the nose cone, pushing out thepiston or wadding, blowing the nose cone/payload off and the parachute.What if you put the charge in the bottom of the payload section pointingdown into a "charge capture tube" (for lack of the right word). This wouldcertainly blow the nose cone/payload section off the rocket but would thenose cone/payload pull the parachute out?There are other combinations of this but I am curious if this methodwould even work.ThanksMike

I put the charge in the bottom of the payload facing up.the payload section is a closed breach smooth bore cannon, made of krafttubing.that makes it an antique cannon by AFT specs even.the chute is covered totaly in a LOC Nomex Blank and is the cannon wading infact.It is packed on top of the charge.the shock cord is put on top of the nomex and the ccone then just fits on.the chute cannon charge then pushes the nomex out the tube like the BlackPowder Cannon it is.I use PalmerCo chrages, and blow it out or blow it up ;-)the charges are made of kraft paper with the Oxral match hot glued in thebottom.BP is added till the tube is almost full , then dog barf added to fill,masking tape for closure.

How much does direction of ejection charge matter?

Mar 19, 2005 41 Replies

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Phil Stein 21 years ago

Give me a little time & I'll take pictures & write something up.

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Phil Stein 21 years ago

The piston is installed in its usual location. The charge from the altimiter is located where ever you usually put it (forward of where the piston is.) The piston isn't used as a piston in this setup but does prevent the charge from trying to blow the motor out.

If you wanted to use the piston, you can get away with a small hole in the top of the piston to pass the wires (going to the charge) through.

Also, if you are doubtful about your setup working, ground test it.

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