NASA Highly Reusable Space Transportation study

FutureSpaceTourist

ACCESS: Top Secret
Joined
Mar 11, 2010
Messages
589
Reaction score
16
Between 1995 and 1998 NASA funded a study into Highly Reusable Space Transportation (HRST).

[quote author=http://science.ksc.nasa.gov/shuttle/nexgen/hrst_main.htm]
A rocket works by combining fuel with oxidizer, but all the oxygen, unlike cars or airplanes, is carried aboard the rocket. Not so for cars or airplanes. The physics of a rocket mandates that most of the rocket at lift off is thus propellant. Most of a rocket's weight is not rocket structure holding the propellant nor other parts of the rocket. By weight, a rocket at liftoff is mostly propellant. Some numbers - a typical passenger jet plane may be 30% propellant, in this case jet fuel, and 70% aircraft, by weight. For comparison, a rocket may be in the range of 85% propellant and 15% rocket, by weight. This 15% does not make for an easy design that will be robust and can focus well on affordability, ease of operation, reliability or safety. At 15% of something to hold 85% of something else, the preoccupation is mostly on getting off the ground, and if need be return, such as with the Space Shuttle. Expendable launch vehicles do not significantly depart from this basic reality. Separating and dropping stages during ascent is simply a means of discarding structure that is no longer required for the rest of the ride, but which was still just as fragile and weight limited.

Now imagine some of the oxidizer was taken from the air as the spaceship traveled through the atmosphere. The topic of Rocket-Based Combined Cycle spaceships was explored extensively in the HRST work as to it's effects on affordability of operations, reliability and safety. Potentially, such technology using SCRAM cycles, if the barrier of thermal management and materials both external and internal could be overcome, could get to where an aircraft-like spaceship, taking off horizontally, would be as much as 35% "ship" and *the rest propellant, vs. 15% "ship" today. The possibilities are explored here in the broader context of the effect such technology could have on creating routine, affordable access to space.
[/quote]

The above web page contains links to various documents produced as part of the study, including the final report http://science.ksc.nasa.gov/shuttle/nexgen/Nexgen_Downloads/HRSTOpsIntRepor.pdf. This report assesses and compares about 10 different advanced concepts, with a focus on operations.
 

FutureSpaceTourist

ACCESS: Top Secret
Joined
Mar 11, 2010
Messages
589
Reaction score
16
From the final report cited above:

The concept ranked with the most benefit is the Horizontal-take-off-Horizontal-Landing (HTHL) single-stage Supercharged Ejector Ramjet (SERJ) with launch assist (Argus).

The Argus SSTO vehicle is described in the attached AIAA paper, from which the attached pictures come. Some details:

[quote author=http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.33.6876&rep=rep1&type=pdf]
Argus us designed to be a low cost cargo delivery system to LEO. A magnetically-levitated sled (Maglifter) is used to provide an initial ground-based launch assist. LOX/L2 supercharged ejector ramjet engines provide the main motive power to the vehicle. These engines operate in supercharged ejector, fan-ramjet, ramjet, and pure rocket modes during ascent and can provide several minutes of powered loiter time during landing. The baseline configuration can deliver a 20,000lb. payload to a 100 nmi. circular, 28.5 deg. inclination orbit from Kennedy Space Center and approximately 11,100 lb. to the International Space Station (ISS). For additional revenue, a 'passenger module' can replace the payload in the payload bay to transport up to six passengers to orbit and back.
[/quote]
 

Attachments

  • argus.pdf
    124.5 KB · Views: 10
  • argus ssto.JPG
    argus ssto.JPG
    23.6 KB · Views: 108
  • argus ssto 3-view.JPG
    argus ssto 3-view.JPG
    46.8 KB · Views: 104

mz

ACCESS: Top Secret
Senior Member
Joined
May 28, 2007
Messages
676
Reaction score
16
Thanks FST for the link! Basically, they think that one should not care about performance that much, instead make the thing sturdy:


Operations and Overall Affordability: Propulsion and Engines:
• De-rate the engine operation to reduce stress. Design and certify to one level, operate at less (example: engine operation at 90% of design/certification thrust). This should extend life through a direct increase in MTBF for many major components. A study by MSFC/Rocketdyne, "Rocket Engine Life Analysis", August, 1996, indicates a significant increase in engine life expectancy, from 10's to 100's of flights between overhauls, when operating engines at 90% rated capacity.
• Reduce start/stop transients for engines through either technologies (laser ignitors) or approach (increase propellant capacity and slow the startup). Any decrease in engine ramp rate correlates to reduced thermal shock loading on materials and increased life.
• Eliminate hypergols. Use fluids already common to the main propulsion system such as LOX or LH2. Volume and hence weight has previously limited use of LH2 in favor of toxic fluids.
• Make propellant tanks more robust (through increased weight or stronger materials with higher design factors of safety or both). This should simplify checkout and loading procedures by eliminating complexities associated with fragile tankage.
• Make umbilical interfaces more robust on the vehicle to enable automated connection and disconnection of umbilicals with simple checkouts. Fragile, flight- weight structures on the vehicle side severely constrain (or eliminate) options for automation of umbilical connections at multiple interfaces Automation would move connection time towards minutes rather than days.
• Place LOX tanks aft. This simplifies facilities for loading as well as loading procedures by eliminating failure modes and additional complex systems. If using engine gimballing, this may mean increased control authority. This in turn may involve engines placed farther apart.
• Swing arms should be eliminated or vent lines placed fully on-board. The simplification of interfaces could be improved by eliminating vent arms for cryogenic boil-off. Overboard venting may involve more robust thermal protection systems and structure capable of resisting ice formation and possible impact. Fully on-board vent lines, as another option, can be routed down and integrated with ground umbilicals to reduce overall complexity.
• Add propellant capacity to allow extended loiter [airbreathers] and eliminate non- return-to-launch-site abort modes. This eliminates costly stand-by-contingency infrastructure.
Vehicle and Structure: • Increase robustness to eliminate regular intrusive checkout and inspection. This
should be targeted on an increased tolerance to corrosion and stress.
• Thermal protection systems should increase weight if required to make more robust. This enables use of a higher impact material that is damage resistant.
• Thermal protection systems should be purge-less for zero interface support requirements. This may mean an increase in foam thickness. The elimination of confined spaces and creation of a purge-less condition is a target.
• Increase landing gear robustness. Size correctly for true “walk-around check only” reusability at expected loads, speeds and operating conditions.
• Closed compartments should be eliminated. As stated several times in the body of the report, the negative impact on operations in terms of time and resources that result from confined spaces in the vehicle cannot be overstated.
Health Monitoring and Control:
• Integrated Vehicle Health Management should increase the number of sensors focused on maintainability (ease and speed of troubleshooting, fault detection and isolation, and checkout). This should permeate fluid, electrical, and structural systems - not just black boxes.
• Electrical onboard power should provide simple, single connection and on-board conversion for simplified interface to ground during processing (airplane like). On- board ability to power specific systems as required should be built in.
Supportability:
• Increase accessibility by means of aircraft-like access panels. This includes motorized, hinged, latched, pull out access trays and operator access via push button. Maintainability, post troubleshooting, is increased, reducing mean time to repair.
• Design for self-ferry. Simplified infrastructure via the on-board accommodation of most, if not all functions required for take-off is a target.
• Use commercial-off the shelf (COTS) hardware with little or no modifications to get flight weight, i.e., aircraft weight.
Payload:
• Create more independence for the payload to simplify integration. A containerized system with a very simple, robust loading operation (sea-land type, self-sustaining containers) is a target.


I think a large proportion of newspace people have been saying things like this for a while, but it's nice to read such detailed descriptions from these NASA guys from the various centers... from 1998. :)
 

FutureSpaceTourist

ACCESS: Top Secret
Joined
Mar 11, 2010
Messages
589
Reaction score
16
mz said:
I think a large proportion of newspace people have been saying things like this for a while, but it's nice to read such detailed descriptions from these NASA guys from the various centers... from 1998. :)

Yes, NASA has no problem generating good ideas/making progress on paper (inflatable space habitats anyone?), it's a real shame that politics and corporate desires to maintain the status quo have largely prevented them from implementing them ...
 

topspeed3

ACCESS: Secret
Joined
Jan 31, 2011
Messages
246
Reaction score
36
Website
max3fan.blogspot.com
mz said:
I think a large proportion of newspace people have been saying things like this for a while, but it's nice to read such detailed descriptions from these NASA guys from the various centers... from 1998. :)

Yes, NASA has no problem generating good ideas/making progress on paper (inflatable space habitats anyone?), it's a real shame that politics and corporate desires to maintain the status quo have largely prevented them from implementing them ...
Yes that Maglifter system would have made space access almost free of charge....compared to present system.
 

Similar threads

Top