ATK Thiokol Propulsion says it is on track to start tests in late 2002 of an interim demonstrator booster for Phase II of the US Defense Department, NASA and industry's Integrated High-Payoff Rocket Propulsion Technology (IHPRPT) programme. The aim is to double US launch capability by 2010.
"We are looking at propellant technologies, advanced case materials, new nozzle designs and new control technology," says Thiokol advanced technology programmes business development manager, Michael Blair. "We're planning on running the interim demonstrator at the end of 2002, and the final Phase II demonstrator around September 2004," he adds.
The first phase culminated in successful static testing of an experimental booster last November. Set against a 1995 technology standard booster, Thiokol achieved a 15% cut in costs, 15% increase in mass fraction, a 2% increase in specific impulse and a 25% reliability increase. Overall, Thiokol generated a 15.2% cost saving, a 17.1% mass fraction increase, a 2% specific impulse improvement and an estimated 25.2% gain in reliability.
Targets for Phase II include a 25% cost saving, 25% mass fraction improvement, 4% specific impulse gain and a 50% reduction in stage failure rate. Respective targets for Phase III, due to be completed in 2010, are 35%, 35%, 8% and 75%.
Although reluctant to detail its Phase II design, Thiokol plans to build on the technology developed for the Phase I booster. Using technology derived from the USAF's High Performance Case Assembly Technologies (HPCAT) programme, a newly developed prepreg tape was used in the motor case dome to reduce weight, and a new silica-filled ethylene-propylene-diene monomer internal insulation material was used in the static test.
A new, denser propellant containing RDX was also used in Phase I, while moulded structural parts were used for the first time in the construction of the nozzle. This also contained a thrust vector actuator adapted from combat aircraft.
Source: Flight International
