Additional Studies of the Application of the MCD Criteria

The Air Force program office for the development of the MCD/SLV ceased to exist on or about June 1, 1968, soon after it announced the start of the "MCD Feasibility and Study Phase." However, a portion of the office remained. Its duties were to conduct in-house studies of the MCD/SLV, coordinating with the Air Force Rocket Propulsion Laboratory at Edwards AFB, and manage existing and any further contracts with industry. The Aerospace personnel who assisted in these efforts were former members of my team.

Between 1966 and about 1970, Aerospace and nearly all major industry contractors studied the MCD/SLV and the MCD design of SLV components. The work was performed under in-house sponsorship and under contract to NASA and the Air Force. Many of these studies are briefly reviewed. These studies are in addition or supplement to the Aerospace, TRW, and Boeing work described in previous Columns. They show the scope and extent industry participated in the understanding and application of the MCD criteria. Those studies in which I played an active part are identified by a double asterisk (**). Since I was officially out of the loop as of June 1, 1968, the information that I am reporting on, conducted after that date, was obtained from not-to-many reports and briefings passed to me by sympathetic individuals, and from the excellent research performed by Lt Col London; see Column dated February 5, 1997.
 
 

A simplified MCD analysis identified and redesigned those subsystems of the TITAN IIID, 5-segment motor strap-ons that would result in a more uniform degree of sophistication among components and a reduction in recurring costs.

The MCD analysis was used to calculate the dollar values of a pound of weight and a point of specific impulse of each stage. It showed that a new propellant of higher density, specific impulse and cost would not be cost effective if used in any of the Minuteman ICBM stages.
 

In the proposed configuration, the diameter of the Stage 1 core, enlarged from 10 to 15 feet, supported four, rather than two, Aerojet engines. The Martin-Marietta design followed the same construction, load paths, materials and fabrication processes as used in the TITAN III family. The Aerospace design replaced the high-strength aluminum alloy tank skins, heavily machined to provide integral longitudinal stringers and thickened weld edges, with a ring-stiffened, lower strength aluminum alloy sheeting of high weld strength. The airframe weight increased by 7.2% while the recurring costs decreased by more than 50%. The tank skins were no longer scratch sensitive. It was suggested that a small increase in burn time be used to compensate for the increased tank weight, although the decrease in payload weight would be negligible. The reduction in recurring costs in program management, engineering, inspection, etc., was identified.

Pressure-fed, liquid propellant strap-ons, designed to match performance and abide by the vehicle and handling constraints of the proposed 156 inch, 3-segment solid rocket motors, were estimated to cost more than 50% less. The nonrecurring costs were not estimated but were obviously appreciably less. As recorded by Lt Col London, TRW extended this study in October 1968.

Procedures for designing MCD stages traveling from a low parking orbit to the synchronous equatorial orbit were defined. A design example showed that a pressure-fed, storable, bipropellant stage was far more cost effective than an advanced pump-fed, oxygen/hydrogen propellant stage, although the specific impulse of the latter propulsion system was approximately 50% higher. The study also showed that the stage should be relatively sophisticated even when launched by an MCD/SLV.

This study, conducted by the Materials Laboratory at Aerospace, provided a procedure for selecting minimum cost propellant tank materials. The parameters considered were the requirement for non-destructive testing, fracture toughness, weld efficiency, and material and fabrication costs. (Ref: "Designing Cost-Effective Pressure Vessels Based on Fracture Mechanics," L. Raymond, Proceedings of the Second International Conference on Space Engineering.)

• NASA Sponsored Study of Low Cost Launch Vehicles (discussed in the May 15,1997 Column). Completed in June, 1969.
This comprehensive and detailed study, defined by NASA as part of the National Space Booster Study, employed the MCD criteria in designing a family of low cost launch vehicles. The final configuration differed somewhat from Aerospace's design. The recurring cost was estimated at about one-fourth the cost of current launch vehicles. Special note was made of the following facts: payload costs far exceed launch vehicle costs, and payload costs may be appreciably reduced by designing to the MCD criteria and launching them on an MCD/SLV.
• Air Force Sponsored Study of MCD/SLV Configuration Equal to the Shuttle in Payload Weight Capacity. Completed in 1980.
The vehicle configuration was an enlargement of the vehicle designed in the NASA study. The estimated recurring cost in production, having a payload weight of 65,600 pounds to LEO, was estimated at less than $1,000 per pound. It was reported that augmenting this study was opposed by NASA and certain members of Congress. The results of this study were reported publicly by D.E. Fritz and R.L. Sackheim at the AIAA/SAE/ASME Joint Propulsion Conference held in 1982.

The major design activity was requested by the Air Force: configure a new baseline design of a family of MCD/SLVs, taking advantage of past and current industry studies. Parallel staging, using 2 and 4 strap-ons, were computed to be cost-optimum, obviously a configuration the aerospace industry could handle and whereby the commercial industry could be excluded..

The initial, in-house, study evaluated the Aerospace MCD/SLV design. They called their slightly modified configuration COLV, for cost-optimized launch vehicle. This configuration was used in the display stage to which the 250,000 pound thrust TRW engine was attached.

Martin-Marietta, McDonnell Douglas, and North American Rockwell competed for this contract. Boeing's dominant design feature was to configure the propellant tanks as spheres rather than cylinders with dome ends, maintaining the Aerospace design feature of common bulkheads between the fuel and oxidizer. The configuration traded a small loss due to increased aerodynamic drag for an appreciable decrease in tank weight. The initial configuration did not include strap-ons; however, the final configuration used parallel staging as used in Aerospace's baseline design. Launch costs ranged between $700 and $1100 per pound of payload to LEO, depending upon the payload weight configuration. The Air Force program office applied the MCD criteria in devising the management plan for the development of the vehicle.

From 1965 on, Martin-Marietta, the manufacturer of the TITAN series of SLVs and most affected by the procurement agencies acceptance of MCD, closely tracked Aerospace's MCD activities. They conducted parallel studies on nearly all items, particularly the MCD/SLV that compete with the TITAN series. They found the advanced version of the Aerospace MCD/SLV, in which sea recovery of the first stage further reduced recurring costs, particularly worrisome. There were instances where the study results did not agree, but the disagreements were always resolved.

The following major, aerospace contractors studied the MCD/SLV in-house to various depths:

Space Division of North American Rockwell Corporation
Space Division of Chryster Corporation
McDonnell Douglas

The Air Force invited me to attend a meeting that was billed as "Orientation Tour of Minimum Cost Design (MCD) Booster Hardware at the TRW Capistrano Test Site." I secured permission to attend. The meeting was attended by about 30 Air Force and 6 Aerospace personnel. The tour was actually a "wake" mourning the demise of MCD, and the closure of MCD and the myriad of studies it initiated. The display booster stage that Boeing built, to which TRW attached the 250,000 pound engine, was on display near the rocket test stand. I asked a TRW staff member what it was doing there and he related the following story.

For many months they had tried to get President Nixon to visit the facility and have him see the stage. Given the opportunity, they planned to brief the definition of MCD, and inform him of the many millions of dollars industry has spent in corroborating the criteria and the large, potential reduction in space costs. The enticement for his visit was for him to play "astronaut" in the lunar module descent and landing simulator located at the test site. They were unsuccessful in persuading his scheduling secretary to include this visit as part of one of his west coast tours.

Do you know of additional MCD study activities that have not been covered in these columns? [no discussions were submitted for this question]

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