Monday, February 13, 2012

Extreme Performance Rockets (from 2007)

These are oldies but goodies, and a few of them are newies to me. Including these two:

This rocket looks like a giant egg lofter (perhaps for ostrich eggs?) but is actually a 6 inch can-sat launcher with a minimum diameter bottom for 4inch motors. This flyer is the king of low-weight altitude rockets, and this one is no exception at about 10 lbs empty. That is not bad at all for a rocket with a 6 inch payload.

The specs for this rocket are insane:
LOA: 150 inches (about 12 feet)
Booster: CTI Pro98 N2500 (5.5 second burn, 13766 newton seconds)
Sustainer: CTI Pro98 N1100 (12.2 second burn, 14044 newton seconds)
2nd stage burnout: Over 1700 mph
Expected apogee: Over 90,000 feet

This is an excellent initial test of what two N motors can do. There is no doubt that, even without staging delays, N motors can break 100,000 feet in a well built, but largely conventional rocket. Replacing the first stage with an N5800 motor would increase the build requirements, but would probably have been enough to push the design past 100,000 feet. With a 10 second staging delay, one wonders how much the apogee could be increased again. The question remains, can two N motors launch a rocket to space with the right staging delay? Projects like this are a good way to test the waters first. Clearly the choice of motor is all important. Non-optimal O motors (like the stubby CTI O motors) and skinny M motors like the Ellis Mtn M1000 have been used in 100,000 foot attempts. Yet similar performance is possible with two N motors when motors like the incredible N1100 are employed. Two N1100 motors would be very interesting to fly, but the risk of the rocket drifting into horizontal flight are greater. At very low thrust, fin thickness can be held to a minimum as can airframe weight.

Additional Rumpty Dumpty information at TRP

XPRS Gallery from 2007


rafa said...

i like the shape.
how stable is it in flying?

High Power Rocketry said...

Not sure how stable it is, but I suspect there were simulations used to make sure it would be stable. Possibly it needed nose-weight to get the center of gravity forward enough for a good flight. This guy is an expert so I am sure he got it working!