Tempest is a Public Missiles kit that is designed to be flown on a Hypertek J hybrid motor. For parachute deployment I used an Adept ALTS-25 altimeter.  I also used a home built G-switch timer for ejection back up and a Walston transmitter for location finding.  Tempest was built and first flown in the spring of 1996. 

Tempest Launch Photos

My hybrid rocket (a modified PML Tempest) is on the launch pad at Bonneville Salt Flats during LDRS-17 in August of 1998.  This rocket has a Hypertek motor system that burns liquid nitrous oxide (N₂0) as the oxidizer and ABS black plastic as the fuel. It uses an Adept ALTS-2 altimeter for apogee deployment.  It also uses a home built G-switch timer for ejection backup and a Walston transmitter for radio finding.  (The Walston unit was of course not needed at the Salt Flats. There is nothing there for the rocket to hide behind!)

Close up of my hybrid rocket on my launch pad at LDRS-16 in Hartsel Colorado.  You can see the fill stem inserted into the motor to supply the nitrous oxide for filling the on-board flight tank. The vent hole on the side of the rocket is where the liquid nitrous will begin to vent once the on-board tank is full. Two small hoses connect into fittings just below the horizontal blast deflector.  One hose supplies liquid nitrous and the other one supplies pure gaseous oxygen that is used to ignite the motor.  A high voltage transformer is in the gray box hanging just under the angled blast defector.  A spark from this transformer is used to ignite the motor. The launch pad itself is made from regular plumbing pipes and associated elbows and tees.  The launch rod is held in place by a 1/2 inch drill chuck.

Photo by Mary Nielsen

This is me with my first Hypertek hybrid motor rocket.  This is a stock built PML Tempest kit that I first flew on May 11, 1996.  This was the first hybrid launched in Idaho.  I used the small orifice for maximum thrust duration. This is the J100 configuration.  The ALTS-2 altimeter reported 4523 feet.  Unfortunately, after many flights, this rocket eventually crashed due to a torn shock cord on a less than totally vertical flight.  When I built a new one, I stretched it about 10 inches.  The stock Tempest kit is, in my opinion, a bit short on room for the parachute and recovery harness. I also switched to tubular nylon and threw away the elastic shock cord.

Peak altitude was 4523 feet.

The Tempest had many successful flights but this is what you get when an elastic shock cord eventually breaks! Tubular nylon is a much better choice for large rockets.

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