Mass growth in space vehicle and exploration architecture development

Aeromechanics and Vehicle Configuration Demonstrations. Volume 3: A Hybrid Probabilistic Method for Estimate Design Margin

“…Table 5 contains a list of four historical space plane concepts which experienced mass growth. [130] The first concept on this list is the X-20 Dyna-Soar, an Air Force space plane designed to conduct lifting re-entry research. The original design called for it to be launched on a manrated Titan II booster.…”

“…This massive mass growth in conjunction with technological hurdles led to the cancellation of this program in 1990. [130] The next program working towards an SSTO was the X-33 program. This was a demonstrator vehicle designed to test technologies such as composite propellant tanks, metallic thermal protection systems, and aerospike engines.…”

“…The X-33 program eventually ended with 75% of the vehicle assembled in March of 2001. [76,130] [130] Vehicle Percentage Mass Growth X-20 33 % X-30 800 % X- 33 45 % X- 37 25 % The only member of this list to actually become operational is the X-37. This reusable spaceplane has made two flights to orbit after being lofted by an Atlas V 501 launch vehicle.…”

“…Additionally, these large lists can be broken down into two generalized sources of growth: out-of-scope and in-scope growth. [130,82] The first overarching category identified as a mechanism of mass growth is out-of-scope changes; these are simply defined as a change in requirements by the procuring authority. [6] These changes can demand a vehicle with more capability.…”

“…[81,33] As the new technologies increase in TRL and MRL, the originally estimated benefits tend to fall short of the original, optimistic estimates. [130] A realization of a technology which does not deliver the intended performance benefits will result in a net increase in mass. Changes that occur as the design progresses beyond the proposal stage and the design criteria and requirements become better defined.…”