Stridget - 
Stretched Midget


Tridget - 
3-Stage Midget

Midget Fleet




The Midget has become one of my favorite rocket types.  As a kid, my original Midget was my only two stage rocket.  As a BAR, that same rocket gave me my first two-stage flight, and it was thrilling.  Both the booster and then the sustainer seemed to burn forever - the rocket just climbed and climbed... 

Since that magical flight ended with a zipper, I decided I'd better build a replacement for regular use and retire my precious original. 

Tridget
Several minor changes were made to the basic K-40 to make the rocket better.  I used 3/32" balsa for the fins (instead of 1/16"), and extended the body tube from 4" to 5" to provide a little more space for the recovery system - hence the name Stridget for Stretched Midget. 

To save some effort, I planned to use the same booster I had already made for my old Midget.  One minor improvement was extending the booster body tube just enough to accomodate an aft engine block which ensures proper separation of the booster.  Alas, this booster (shown above on the left) met an untimely end; it was damaged beyond repair while attempting to remove a stuck (bulging) booster motor. 

The yellow booster on the right was built to replace it.

Another important detail of the Stridget is that the tailcone was changed to taper from BT-50 down to BT-5 (instead of BT-50 to BT-20).  This makes for a more abrupt transition, and requires changing the fin template slightly, but provides an unstepped connection to the booster. 

I got a little carried away sanding the fins, and ended up rounding the tips, but the basic shape of the Midget still comes through clearly. 

It has made many successful flights, but a few bad ones, too. A booster CATO sent the rocket on a short, unpowered flight.  Fortunately, my daughter got a hand on it on its way down, breaking its fall and leaving it unscathed.  Later, at another launch, the sustainer failed to ignite - clay in the nozzle of the 1/4A3-3T - and the rocket lawndarted in the street. Ouch!  The nosecone was flat-spotted and swallowed by the body tube, and the fin tips were a little chipped.  But a replacement nosecone was found and the forward 3/8" of body tube cut off to provide a clean connection to the new nosecone.  The Stridget would fly again. 

 




Tridget - Three Stage Midget
Motivated to fly a three-stage rocket, I decided to build a second, intermediate booster (shown at right) for the Stridget.  I scaled the booster fins down somewhat, and, using Rocksim, was able to determine the new three-stage configurate would be stable. 

On its first three-stage flight, two bad things happened: Since there was no aft engine block on the second booster (nor could there be), the rocket spit the 2nd stage motor when the upper stage lit, but the 2nd stage stayed stuck onto the tip of the sustainer motor.  The exhaust from the upper stage motor fried the 2nd stage and blistered its paint. 

To add insult to injury, the sustainer failed to completely eject the laundry, and the rocket took a core sample.  Ugghhh! 


Tridget

After the rocket had sat on my workbench for several weeks with a status of FUBAR, my neighbor was studying it and declared that it could be repaired.  After I studied it, I realized that although its body tube was wrinkled, that it was still straight.  The rocket could continue to fly albeit with a dingy complexion. 

One more successful two-stage flight was performed. Then I decided to try another three-stage flight.  The 2nd booster was sanded out and CA soaked to repair the burn damage.  Much more care was taken in preparing the stack of three motors.  This time I put as much tape on the 2nd motor as possible to get the best friction fit in its stage.  It flew at DARS' NTHP two weeks ago (circa Feb 2002).  It drew positive comments from the LCO, then successfully flew with both boosters separating as desired. 

It's still dingy, but I'll keep flying it.  Even if it's not the best looking rocket in my fleet, it still brings me great joy.


Epilog: The rocket was lost just before Christmas in 2002.  While I had several kids helping track it, I had an inexperienced boy on the upper stage, and I failed to coach him and to back him up - my bad.  While I was supporting the 2nd stage tracker, he lost track of the upper stage.  Man, I was bummed.  But it was my fault.  I should have backed him up or let him track another stage.
 


Tridget 2 - Another Three Stage Midget

After the first Tridget was lost, the boosters were recycled.  They had both seen several flights and were getting ragged, so I cut off their fins and built new boosters along with an all new sustainer.  Here it is, ready to go.


Below are a couple of recent shots of the Tridget on the pad.  In neither case did I get a liftoff shot - all I got was smoke


Sept 20, 2008


November 22, 2008

Doug's Rockets Homepage

12-21-2008