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Battle for the space shuttle (20): the aftermath (3)
Langley taking the helm - the shuttle dream ain't dead yet
"Advanced space transportation studies have been conducted at the Langley Research Center recently. The Orbit-on-Demand Vehicle Study focused on concepts capable of rapid launch. The Shuttle II study considered concepts with the potential to reduce the cost of transportation to orbit for payloads in the Titan III / 1971 Space Shuttle class.
Eleven design concepts for vertical (V) and horizontal (H) take-off launch-on-demand manned orbital vehicles were examined. Attention was given to up to three stages, Mach numbers, expendable boosters, drop tanks (DT), and storable (S) or cryogenic fuels. All the concepts featured lifting bodies with circular cross-section and most had a 7 ft diam, 15 ft long payload bay as well as a crew compartment.
Preliminary results study are used to identify major technology issues for development of a quick response vehicle. Baring a major technological breakthrough, reasonable vehicles are found to require significant advances in propulsion, structures, materials, and flight mechanics technology. Vehicle concepts using normal growth technology predicted for the 1990s are compromised by expendable hardware or by unmanageable size and complexity.
Operational analyses of the vertical-launch and horizontal-launch takeoff vehicles show that the latter have more inherent operational utility. The supply of liquid hydrogen propellant at alternate sites is a major issue; however, propane may be a viable option for at least one concept. Propellant for orbital maneuvering significantly increases gross weight for many of the concepts. This increase is greater for horizontal-takeoff systems because of their larger orbiters.
Performance requirements and design features of the next generation of manned launch vehicles are discussed. The vehicles will launch within minutes of demand and will have a several-day turnaround time. Launch and landing sites will have minimal facilities. Baseline requirements comprise carriage and return of a 5000 lb, 7 ft diam, 15 ft long payload, a 160 n. mi. polar orbit, a 200 fps on-orbit delt-V capability, provisions for two men for 24 hr, an 1100 n. mi. cross range option, 500 flights/vehicle, land on 10,000 ft runways, and be acceptable passing over populated areas.
A preliminary design study has also been completed for a larger, fully reusable, single-stage-to-orbit transatmospheric vehicle. The specified mission capability was to lift a 20,000 lb payload to low earth orbit. A ground accelerator-assisted horizontal take-off was chosen to increase operational flexibility. The multi-mode propulsion system included the use of air-turborocket, ramjet, scramjet and rocket engines. Weight and performance estimates were obtained for the vehicle. A computer package was developed to perform aerothermodynamic analyses of the propulsion modes throughout the flight environment from take-off to low earth orbit. Results are presented for a semi-optimized trajectory. The analysis indicates that a vehicle of this type has great potential for providing low cost, flexible access to space.
However significant advances are needed in propulsion and fuel systems, lightweight durable structures and airbreathing acceleration engines. Trade-offs have yet to be fully explored among the number of stages and horizontal or vertical take-off.
Single-stage vehicles simplify the logistics whether in H or V configuration. Expendable elements impose higher costs and in some cases reduce all-azimuth launch capabilities. A two-stage H vehicle offers launch offset for the desired orbital plane before firing the rocket engines after take-off and subsonic acceleration. A two-stage fully reusable V form has the second lowest weight of the vehicles studied and an all-azimuth launch capability. Better definition of the prospective mission requirements is needed before choosing among the alternatives.
Deleting hydrogen ?
Hydrogen has a high boil-off rate, an undesirable feature if a space plane is to be hold in a fueled alert status. It is expensive, difficult to store, and not readily available at most locations. For these reasons, some vehicles were designed to use no hydrogen - only systems that used a hydrocarbon fuel and liquid oxygen as an oxidizer were analyzed. The results indicate that hydrogen could be eliminated with a small increase in gross weight, and the dry weight might even decrease slightly.
The possibility of utilizing jet fuel (JP) stored primarily in the wings of hydrogen-fueled single stage to orbit has been evaluated and compared to the performance of all hydrogen-fueled vehicle. Results indicate improvements in performance for a wide range of potential payload sizes, particularly when in-flight refueling of the JP fuel is considered as a means of increasing range and mission flexibility."
"Advanced space transportation studies have been conducted at the Langley Research Center recently. The Orbit-on-Demand Vehicle Study focused on concepts capable of rapid launch. The Shuttle II study considered concepts with the potential to reduce the cost of transportation to orbit for payloads in the Titan III / 1971 Space Shuttle class.
Eleven design concepts for vertical (V) and horizontal (H) take-off launch-on-demand manned orbital vehicles were examined. Attention was given to up to three stages, Mach numbers, expendable boosters, drop tanks (DT), and storable (S) or cryogenic fuels. All the concepts featured lifting bodies with circular cross-section and most had a 7 ft diam, 15 ft long payload bay as well as a crew compartment.
Preliminary results study are used to identify major technology issues for development of a quick response vehicle. Baring a major technological breakthrough, reasonable vehicles are found to require significant advances in propulsion, structures, materials, and flight mechanics technology. Vehicle concepts using normal growth technology predicted for the 1990s are compromised by expendable hardware or by unmanageable size and complexity.
Operational analyses of the vertical-launch and horizontal-launch takeoff vehicles show that the latter have more inherent operational utility. The supply of liquid hydrogen propellant at alternate sites is a major issue; however, propane may be a viable option for at least one concept. Propellant for orbital maneuvering significantly increases gross weight for many of the concepts. This increase is greater for horizontal-takeoff systems because of their larger orbiters.
Performance requirements and design features of the next generation of manned launch vehicles are discussed. The vehicles will launch within minutes of demand and will have a several-day turnaround time. Launch and landing sites will have minimal facilities. Baseline requirements comprise carriage and return of a 5000 lb, 7 ft diam, 15 ft long payload, a 160 n. mi. polar orbit, a 200 fps on-orbit delt-V capability, provisions for two men for 24 hr, an 1100 n. mi. cross range option, 500 flights/vehicle, land on 10,000 ft runways, and be acceptable passing over populated areas.
A preliminary design study has also been completed for a larger, fully reusable, single-stage-to-orbit transatmospheric vehicle. The specified mission capability was to lift a 20,000 lb payload to low earth orbit. A ground accelerator-assisted horizontal take-off was chosen to increase operational flexibility. The multi-mode propulsion system included the use of air-turborocket, ramjet, scramjet and rocket engines. Weight and performance estimates were obtained for the vehicle. A computer package was developed to perform aerothermodynamic analyses of the propulsion modes throughout the flight environment from take-off to low earth orbit. Results are presented for a semi-optimized trajectory. The analysis indicates that a vehicle of this type has great potential for providing low cost, flexible access to space.
However significant advances are needed in propulsion and fuel systems, lightweight durable structures and airbreathing acceleration engines. Trade-offs have yet to be fully explored among the number of stages and horizontal or vertical take-off.
Single-stage vehicles simplify the logistics whether in H or V configuration. Expendable elements impose higher costs and in some cases reduce all-azimuth launch capabilities. A two-stage H vehicle offers launch offset for the desired orbital plane before firing the rocket engines after take-off and subsonic acceleration. A two-stage fully reusable V form has the second lowest weight of the vehicles studied and an all-azimuth launch capability. Better definition of the prospective mission requirements is needed before choosing among the alternatives.
Deleting hydrogen ?
Hydrogen has a high boil-off rate, an undesirable feature if a space plane is to be hold in a fueled alert status. It is expensive, difficult to store, and not readily available at most locations. For these reasons, some vehicles were designed to use no hydrogen - only systems that used a hydrocarbon fuel and liquid oxygen as an oxidizer were analyzed. The results indicate that hydrogen could be eliminated with a small increase in gross weight, and the dry weight might even decrease slightly.
The possibility of utilizing jet fuel (JP) stored primarily in the wings of hydrogen-fueled single stage to orbit has been evaluated and compared to the performance of all hydrogen-fueled vehicle. Results indicate improvements in performance for a wide range of potential payload sizes, particularly when in-flight refueling of the JP fuel is considered as a means of increasing range and mission flexibility."
- Archibald
- Word Count: 760