Moonport: A History of Apollo Launch Facilities and Operations|
A Trip by Barge or a Trip by Rail?
The Connell letter pointed up the crucial role of the launcher-transporter in LC-39 planning. Its characteristics determined the design criteria of other facilities. The success of the mobile concept rested on the transfer system; the system's development involved some of LOD's most difficult engineering problems. Understandably, the selection of a transporter became a major event in the LC-39 story. The launcher-transporter fell within the purview of Theodore Poppel's Launch Facilities and Support Equipment Office (LFSEO). A Poppel directive on the October C-4 study indicates that the item, while crucial to LC-39, was a small part of the office's workload:
Cost estimates on a canal system were favorable, but the use of a barge as the launcher-transporter raised a number of engineering questions: How to position the barge and flame deflector at the launch site? What means of propulsion and steering to use? How to ensure a stable platform for the launch vehicle? While Martin Marietta examined these matters in the second part of its C-3 study, LOD stepped up its own inquiry. On 2 November an LOD team inspected the elevating mechanism of a Gulf Coast offshore oil rig. A possible solution to the positioning problem at the launch site involved the use of Texas Tower legs on the barge-transporter. The long tubular legs, actuated by a hydraulic jacking system, would be located at each corner of the barge. While the barge was under way, the legs would be raised until flush with the bottom of the barge. At the launch position, the legs would be lowered to rest firmly on a concrete basin. Then the hydraulic system would raise the barge on the legs to provide sufficient clearance for the flame deflector to float beneath it. However, a Launch Facilities and Support Equipment report opposed the hydraulic jacking system since it would place the launch platform at least 18 meters above ground level. In its place, the report recommended a deeper concrete launch basin with the barge positioned on supports extending outward from the basin walls. A lift-gate (lock) would allow sufficient.water to be drained to permit passage of the deflector beneath the launcher. This plan offered a low profile (the launch platform would be only 2.4 meters above ground level), but this advantage would be offset by the increased costs of the lift-gate and deeper basin.16
Lacking expertise in barge propulsion and stability, LOD hired a Baltimore naval architect, M. Mack Earle, "to review the static and dynamic stability programs . . . and prepare a model test program." Earle's preliminary report warned that LOD would likely encounter problems with the propulsion system in restricted canals. Early in the new year Earle began arranging for a test program at the David Taylor Model Basin in Washington, D. C.17
Martin Marietta Corporation submitted the second part of its C-3 launch facility study on 11 January 1962. The report recommended use of a barge 55 x 41 meters, with 1.8 meters draft. Thirteen kilometers of canal, 61 meters wide and 4.6 meters deep, would service the three-pad complex. Four to six Murray and Tregurtha Harbormaster motors would propel the barge. Rated at 530 horsepower, this large outboard motor was capable of achieving nearly 900 horsepower for limited periods. Estimating 45 pounds of thrust. per horsepower, Martin calculated that six Harbormaster units would overcome the drag of a 60-knot wind. Fixed legs, designed by DeLong Corporation and R. G. LeTourneau, Inc. (specialists in offshore oil drilling platforms), would elevate the barge out of the water at the vertical assembly building, the arming tower, and the launch pad.18
After NASA chose to develop the Saturn C-5 for the moon mission, little time remained to select a transfer mode. On 23 January, American Machine & Foundry Company presented the results of a comprehensive survey that included railway wheels, pneumatic tires, crawler treads, barge, and special ground effects, and recommended a rail-barge combination possibly using mechanical mules.19 Debus agreed with their report; he informed Petrone a week later that he tentatively supported a plan "to let the barge weight be carried by water, but use for stabilization and propulsion a rail which carries only partial weight." The LOD Director reviewed transfer modes with Zeiler, Poppel, and O. K. Duren on 30 January, discussion centering on the merits of another launch vehicle transfer study. Although the group postponed an award in hopes that additional suggesstions might appear, Debus did not intend to wait long. Summarizing the meeting for Petrone, Debus wrote: "It appears urgent that we have a program for the crucial engineering studies and possibly cost estimates for these studies early next week because a decision to proceed on 39 is imminent."20
In this atmosphere, a chance meeting at Huntsville introduced a new transporter to the LC-39 competition. Duren, an Auburn University graduate, had been with von Braun since 1951, most recently as Deputy Chief of the Future Launch Systems Study Office. On 2 February, Duren received a call from Barry Schlenk, a Bucyrus-Erie Company representative. While discussing Titan silo overhead cranes with Thiokol Corporation, Schlenk had overheard a remark about LOD's transport problem. The two men spent the afternoon examining some pictures of Bucyrus-Erie's steamshovel crawler used in the Kentucky coal fields. The vehicle seemed suited to LOD's needs; its characteristics included a leveling capability to balance a load on uneven terrain. Caught up in Schlenk's enthusiasm, Duren called Albert Zeiler about his find. Zeiler was skeptical, but agreed to look into the matter.21
Bucyrus-Erie's steam-shovel crawler, used for surface mining of coal in Kentucky.
Four days later, LOD laid plans for barge, rail, and crawler studies. The staff concurred in a three-month barge study at David Taylor Model Basin, employing a 1:10 scale model of the barge. Additional tests would be run in a wind tunnel with a 1:60 scale model. A consulting engineer, William G. Griffith, would assist the Launch Facilities and Support Equipment Office on another rail study, this one concentrating on dynamic loads and foundation costs. Poppel's group (LFSEO) would follow up the Bucyrus-Erie lead with an inspection of the crawler shovel.22
When Donald Buchanan and George Walter arrived in Washington on 20 February, David Taylor Model Basin officials brought some uncomfortable facts to light. LOD's proposed canals were too narrow and would cause serious propulsion and steering problems. The steering problem resulted from the venturi effect. The relative motion of water to barge in the 3-meter space between the canal bank and the barge decreased the pressure on the side of the barge, causing a suction effect. The David Taylor officials recommended a wider canal - and that would raise costs considerably. Then wind-tunnel tests indicated that the drag effect in a 60-knot wind might be three times the estimated value. Basin tests also revealed that the arrangement of the six Harbormaster motors, three across the bow and three across the stern, reduced motor efficiency. There were several possible solutions: tugboats fore and aft of the barge, air jets placed below the waterline, and spuds (vertical steel pipes) to anchor the barge in heavy winds. These involved new tests and cost projections.23
In his rail study William Griffith concentrated on ways to reduce the cost of the roadbed. The continuous concrete beam (2.4 meters deep and 3.5 meters wide} supporting the service structure runway at LC-34 cost more than $3,000 per meter - a prohibitive amount for LC-39's proposed 19 kilometers of rail foundation. Griffith proposed, instead, concrete ties supported by rock ballast on vibro-compacted soil. In a 3 April report, George Walter criticized Griffith's suggestion, arguing that the concrete ties and ballast would not stabilize the track horizontally. Walter opposed Griffith's recommendation of curved tracks. In rounding a curve the transporter's outside trucks would each follow a different route (the transporter would ride on four rails rather than two) and would require a complicated switching arrangement. Negotiating rail curves would also pose a serious problem in synchronizing the transporter's drive units and maintaining a balanced load.24
Presented with contradictory reports, LOD asked Connell & Associates to conduct a more detailed study. The findings of the Miami firm supported Walter's position. Curved tracks were judged unacceptable because "the switches required would be fantastically complex . . . The matter of maintenance of track alignment of the curves is mother difficult aspect of this system to which an economical solution is not apparent."25 The Connell engineers recommended a perpendicular set of railbeds for north-south and east-west travel with switching from one line to another accomplished by one of the Connell team's own inventions: hydraulic equalizer jacks to raise the truck assemblies and a worm or pinion drive sector gear to rotate them. The Connell report questioned the feasibility of Griffith's foundation. Ballast deflection would occur under the heavy horizontal wheel loads, causing track misalignment. Connell recommended a three-layer foundation: compacted fill, a soil-cement subbase, and a reinforced concrete pavement on top. Concrete ties would be keyed transversely to the reinforced pavement. The Connell proposal would reduce the expense of the foundation by over 50%, but even so LC-39's roadbed figured to cost more than $28 million.26