buglerbilly
07-04-10, 11:08 PM
Ares
A Defense Technology Blog
Doing a 180 - AFRL's Rocket-back Pathfinder
Posted by Graham Warwick at 4/7/2010 7:52 AM CDT
Forget the personal jetpacks, the thing we've waited longest for is a military spaceplane. As Bill notes, the US Air Force is finally getting round to testing the reusable, maneuverable orbital vehicle part, in the shape of the Boeing X-37B. But what about the commensurate quick-turnaround launch vehice?
Well the Air Force Research Laboratory has just released a pre-solicitation notice for its Reusable Booster System (RBS) Pathfinder program. This is to be a subscale demonstrator for a reusable booster that would launch vertically, release an expendable upper-stage stack, and return to a horizontal landing on a runway at the launch site. The full-size RBS is envisioned as replacing Atlas and Delta EELVs some time after 2035.
The Air Force has been studying reusable boosters for a long time and has looked at first stages that glide back to base or fly back under jet or rocket power. AFRL has decided that the most promising concept for RBS is "rocket-back" - carry extra propellant and use the main rocket engines to reverse the unmanned booster's velocity then glide back to a horizontal landing.
Flying backwards (Photo: AFRL)
The Pathfinder program is intended to demonstrate the feasibility of the rocket-back maneuver. Compared with "jet-back", studies show rocket-back offers lower weight, cost and airframe heating, and a simpler design that can meet the RBS turn-around requirement of 48 hours. But it requires the vehicle to fly at significantly higher angles of attack as it pitches over to reverse its flightpath.
Pathfinder is envisaged as a four-phase, 48-month, $33 million program. Up to three companies would be awarded Phase 1 study contracts totalling $4.5 million, after which one team would be selected to design the demonstrator and conduct first a propulsion-system ground test then at least two booster flights followed by three or more rocket-back tests.
A notional rocket-back test flight meeting the program goals would involve launching vertically and flying to a simulated staging point on a 20deg flightpath at Mach 7.5, then initiating the rocket-back maneuver to turn the vehicle through 180deg within 5 miles, ending up at 50,000ft on an 8deg glidepath back to the runway. During the maneuver, maximum angle of attack would reach 180deg and acceleration 7g.
Rocket-back flowfield (Photo: AFRL)
Pathfinder has some other goals, all tied to the envisaged full-scale RBS. These include demonstrating responsive, low-manpower launch operations; use of liquid-oxygen and kerosene propellants; integrated system health management; and aerodyamic configuration traceability to the full-size system.
A Defense Technology Blog
Doing a 180 - AFRL's Rocket-back Pathfinder
Posted by Graham Warwick at 4/7/2010 7:52 AM CDT
Forget the personal jetpacks, the thing we've waited longest for is a military spaceplane. As Bill notes, the US Air Force is finally getting round to testing the reusable, maneuverable orbital vehicle part, in the shape of the Boeing X-37B. But what about the commensurate quick-turnaround launch vehice?
Well the Air Force Research Laboratory has just released a pre-solicitation notice for its Reusable Booster System (RBS) Pathfinder program. This is to be a subscale demonstrator for a reusable booster that would launch vertically, release an expendable upper-stage stack, and return to a horizontal landing on a runway at the launch site. The full-size RBS is envisioned as replacing Atlas and Delta EELVs some time after 2035.
The Air Force has been studying reusable boosters for a long time and has looked at first stages that glide back to base or fly back under jet or rocket power. AFRL has decided that the most promising concept for RBS is "rocket-back" - carry extra propellant and use the main rocket engines to reverse the unmanned booster's velocity then glide back to a horizontal landing.
Flying backwards (Photo: AFRL)
The Pathfinder program is intended to demonstrate the feasibility of the rocket-back maneuver. Compared with "jet-back", studies show rocket-back offers lower weight, cost and airframe heating, and a simpler design that can meet the RBS turn-around requirement of 48 hours. But it requires the vehicle to fly at significantly higher angles of attack as it pitches over to reverse its flightpath.
Pathfinder is envisaged as a four-phase, 48-month, $33 million program. Up to three companies would be awarded Phase 1 study contracts totalling $4.5 million, after which one team would be selected to design the demonstrator and conduct first a propulsion-system ground test then at least two booster flights followed by three or more rocket-back tests.
A notional rocket-back test flight meeting the program goals would involve launching vertically and flying to a simulated staging point on a 20deg flightpath at Mach 7.5, then initiating the rocket-back maneuver to turn the vehicle through 180deg within 5 miles, ending up at 50,000ft on an 8deg glidepath back to the runway. During the maneuver, maximum angle of attack would reach 180deg and acceleration 7g.
Rocket-back flowfield (Photo: AFRL)
Pathfinder has some other goals, all tied to the envisaged full-scale RBS. These include demonstrating responsive, low-manpower launch operations; use of liquid-oxygen and kerosene propellants; integrated system health management; and aerodyamic configuration traceability to the full-size system.