21st century space transportation system design approach - HL-20 personnel launch system

A trajectory design and optimization tool named Mission is developed to operate within a multi-disciplinary analysis tool environment for conceptual design of aerospace vehicles. Mission possesses several features designed to facilitate its set-up and operation within the environment. It receives input via an Extensible Markup Language tagged data file. The tree structure of the tags reflects that of a branched and multi-segmented trajectory, aiding parsing and editing for set-up of data exchange within the environment. Mission uses Xerces, a free library developed by Apache, for parsing the data file. In addition, it is linked to both gradient-based and genetic algorithmbased optimizers, allowing a choice depending on the amount of a priori information available. When little is known about the control variables, an initial guess of their histories may be forgone by initializing the optimization process with the genetic algorithm. Once a solution is approached, the gradient-based method is used. This strategy increases the robustness and autonomy of the trajectory tool operation within the multi-disciplinary environment. Finally, Mission's trajectory integration process is coded for parallel execution via the Message Passing Interface standard. The resultant execution speed increase reduces the relative expense of operating Mission within the multidisciplinary environment. The results of a Crew Transfer Vehicle "abort from ascent" problem are presented to demonstrate and quantify Mission's features. NOMENCLATURE a = base area of nozzle * c = fuel mass flow rate C D = drag coefficient C L = lift coefficient D = drag g = local gravitational acceleration g o = sea level gravitational acceleration h = altitude I sp = specific impulse L = lift m = mass n dv = number of design variables n g = number of trajectory integrations needed to calculate a gradient n gen = number of generations per execution n l = number of trajectory integrations needed to perform a line search n i = number of major iterations per execution n p = number of processors n pop = number of genetic strings in a population M = Mach number p = local atmospheric pressure p c = probability of a gene being crossed over * Member AIAA, Aerospace Engineer. † Research Scientist. ‡ Member AIAA, Senior Research Scientist. § Associate Fellow AIAA, Technical Director. p m = probability of a gene being mutated p sl = sea level atmospheric pressure q = dynamic pressure r = radial coordinate r e = radius of earth r s = execution speed ratio of two parallel runs S = side force S ref = vehicle reference area t = time t i = time required to perform a gradient-based optimization iteration t g = time required to evaluate fitness function values for all genetic strings in population t s = time required to integrate a single trajectory T = thrust v = relative speed of vehicle = angle of attack = side slip angle = heading angle = nozzle pitch angle = longitude = flight path angle feas = SNOPT feasibility criterion opt = SNOPT optimality criterion = latitude µ = throttle se...

show abstract

“…(19) curve shows values of Eq. (19) for discrete n p . The baseline run was used as run 1 in the equation.…”

Section: Hl-20 Abort To Gandermentioning

confidence: 99%

“…In this scenario a Crew Transfer Vehicle (CTV) conceived of in Ref. 19, the HL-20, is carried atop a Titan III expendable launch vehicle (ELV). Launch occurs at the Kennedy Space Center in Florida.…”

Section: Hl-20 Abort To Gandermentioning

confidence: 99%

Aerospace Vehicle Trajectory Design and Optimization Within a Multi-Disciplinary Environment

Windhorst

Galloway

Lau

et al. 2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

show abstract

“…This primary mission, the Design Reference Mission (DRM-1), is for a nominal mission of up to three days for Space Station crew rotation. 17 The mission assumes KSC as the launch site and the prime site for return. The launch inserts the vehicle into a 100-n.mi.…”

Section: Overview Of the Oands Environmentmentioning

confidence: 99%

HL-20 operations and support requirements for the Personnel Launch System mission

Morris

White

Caldwell

1993

Journal of Spacecraft and Rockets

View full text Add to dashboard Cite

The processing, mission planning, and support requirements were defined for the HL-20 lifting-body configuration that can serve as a Personnel Launch System. These requirements were based on the assumption of an operating environment that incorporates aircraft and airline support methods and techniques that are applicable to operations. The study covered the complete turnaround process for the HL-20, including landing through launch, and mission operations, but did not address the support requirements of the launch vehicle except for the integrated activities. Support is defined in terms of manpower, staffing levels, facilities, ground support equipment, maintenance/sparing requirements, and turnaround processing time. Support results were drawn from two contracted studies, plus an in-house analysis used to define the maintenance manpower. The results of the contracted studies were used as the basis for a stochastic simulation of the support environment to determine the sufficiency of support and the effect of variance on vehicle processing. Results indicate the levels of support defined for the HL-20 through this process to be sufficient to achieve the desired flight rate of eight flights per year.

show abstract

“…From the early eighties many studies began worldwide on winged, fully reusable launchers (HOTOL in the United Kingdom, Saenger in Germany, Star-H in France, National Aerospace Plane and HL-20 in the USA [3,19,24]). Most of these concepts were abandoned due to lack of funding.…”

Section: Introductionmentioning

confidence: 99%

A low risk reentry: looking backward to step forward

Monti

Paterna

2006

Aerospace Science and Technology

View full text Add to dashboard Cite

21st century space transportation system design approach - HL-20 personnel launch system

Cited by 26 publications

References 14 publications

Aerospace Vehicle Trajectory Design and Optimization Within a Multi-Disciplinary Environment

Aerospace Vehicle Trajectory Design and Optimization Within a Multi-Disciplinary Environment

HL-20 operations and support requirements for the Personnel Launch System mission

A low risk reentry: looking backward to step forward

Contact Info

Product

Resources

About