[JPA logo]

JPA History Series

Twin Dilemma                      August 16, 1996

Our original space flight balloon launched rocket was designed to use a single large rocket motor.  Just before construction our motor supplier went out of business.  None of the other motor manufacturers at the time had a motor that had the right specifications.  We did, however, find that there was another motor that if used it in pairs would do the job.  The result was we designed a twin motor rocket we thought would solve the problem.  We named the rocket the 'Twin Dilemma'. 

The rocket was the most gorgeous rocket we had ever build.  It was fourteen feet long, with a four inch diameter instrument bay, dropping down to a two inch diameter airframe flaring out to two motor mounts.  The Twin dilemma was designed to be launched from a balloon, but for the first flight we flew her out of a launch box suspended from a frame.  This would have the same dynamic as a balloon launch, just closer to the ground.

For the first test flight we used smaller motor.   This flight was to test the general design and flight characteristics.

The beginning of the end was right at motor ignition.  One rocket motor started two seconds late.  The single motor was powerful enough to launch the rocket out of the box and up to mach.  The problem was with one one motor running the thrust was not centered.  As the Twin Dilemma came out of the box she started to turn.  When the second motor kicked in the rocket headed straight, however, not straight up.  The rocket cruised until the motor that started first then stopped first, (the motors ran for nine seconds).   The rocket then tried to make another turn upward.  However, it was traveling well over Mach one by now and the rocket broke in half from the strain.    The computer in the forward section deployed the parachutes.  The aft section made this evil, wicked whine as it turned and headed for impact.  It crashed about two miles downrange, just the tail was left sticking up out of the desert floor. 

We found another supplier who could make the needed rocket motor and abandoned the twin motor design.

 

The Launch Box

               

Unfortunately there are no ground picture of the rocket.  Here's the launch box just after completion and loading the
rocket in the desert.  The Twin Dilemma was designed for balloon launch.

The Launch

  
Countdown.  The launch box is suspended just two inches above the ground.  This is to simulate a balloon launch. 
The launch crew appears closer then they are.  Their really about 300 feet away from the rocket.
You can see from the off centered flame that only one of the two rocket motors are running as the rocket leaves the box.

                        

                                                                             

                                
                   These are frames from the video of the launch.  You can see the turn the rocket made right out of the box
                   from the off centered thrust.   While she flew the Twin Dilemma was a beautiful rocket.

The End.

                                                 

   The Twin Dilemma completed the turn at 14,000 feet and starting down.  The rocket impacted about two miles
   down range.

               

 

  Back to the JPA home page.


This page was last edited on February 20, 2006
Email comments
to jpowell@jpaerospace.com
Copyright© 2005-2006 JP Aerospace. All Rights Reserved.