Ultra I...

My last gasp at a rocket with world-class performance, the Ultra-I was designed to get the most possible altitude from the Aerotech I32 engine. I've often flirted with such low-average thrust yet long duration motors, and the I32 takes that to an extreme. An average of "only" 32 n/sec (I used to STAGE motors to get 30 newtons in '67!)..

But "only" 32 newtons for 20 seconds! ! ! !!

This boilerplate model flew great on a Rocketflite G100 and with a weighted tail section to simulate the I32 c/g, but then the fins shredded ("became detached by serious aerodynamic pressures and/or shock waves", to you non-Rocket types) on the I65 with which I gave it the acid test. Note that these are not true TTW mounted fins, they only break through slots in the airframe skin, because of the extreme dia of the required motor tube.

This led to the development of the patented McBroom Eight Wraps Of .040 Kevlar Cord Followed By a Layer Of 3/4 mil Carbon Fiber Mat Impregnated With Airbrushed Epoxy method of fin reinforcement. No further tests were deemed required, and the next launch was the full I32 flight.

About all I can say for the flight is that the fins didn't shred. (grin) I chose to fly on a windier than optimum day for the I32, and the rocket weathercocked despite the gentle tilt with the wind. It almost worked. At liftoff, the rocket did indeed weathercock to vertical at about T+3 to T+5... then kept going. By T+15, the rocket was nearly horizontal and at perhaps 1,200 meters, and the I32's mildly progressive thrust curve was starting to kick in (big grin). At last sight, the rocket was trailing tracking smoke, and looked like it might very well have cracked Mach 1 in level flight!

It was so far gone; I didn't even bother to look for it. Like many of my rockets, though, I had my name & addy on the bird, and next spring, nearly six months later, a gent rang me up after finding it. I clocked it by car, and the rocket was found well over three miles from the launch point!

Not all was lost, though. I reused the fins, nose cone, and 'chute.. and the rocket served as a winter home for a family of mice, judging by the nests I found in the soggy airframe tube! I've duplicated the rocket, down to the PMEWo.040KCFbLo3/4CFMIwAE method of fin attachment, but have never flown another I32. Sadly, Aerotech quit making them several years ago, so if any of you rocket folk out there have a live I32... ];-)

Computer projections say that my bird could have cracked 8,100 meters, and the record currently stands at less than 7,000, sooo... I thought about trying another I32 as it should be used, as a 2nd-stage motor. I.e. a full J flight, probably an I280 to the I32 upper stage. That rocket, under ideal conditions, should be able to nudge the vaunted 40,000 meters when you can genuinely say that you "Got Your Rocket Into the Stratosphere"!.


Liftoff of the I32 flight.. another 3 to 5 degrees into the wind, and it might have went as planned! Instead, it was Land Shark Time, and "..incomiiing!!" for some field mice.

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