The outrageous plot of NASA hiring a group of miners for a space mission may remind you of a certain Hollywood movie, but back in the mid-1960s when the space organization was trying to reach the moon, they did, in fact, look towards coal miners and their tools for inspiration. Back then, NASA had just completed designing the Saturn V, the behemoth of a rocket weighing nearly 3,000 tons that would take the first men to the moon, but they had yet to figure out how to deliver this monstrous rocket from the assembly building to the launch pad.
The most obvious choice, the railway, was considered. They even discussed digging a canal and using a barge to transport the heavy rocket. But barges involved many engineering challenges, such as what method of propulsion and steering to use and how to ensure a stable platform for the rocket while it is on the move. A group of engineers were sent off to study the elevating mechanism used by offshore oil rig in the Gulf Coast.
On January 1962, the American Machine & Foundry Company, one of America’s largest recreational equipment manufacturer who produced everything from garden equipment, to atomic reactors, to yachts, presented a plan that involved using a rail-barge combination where the weight of the rocket was supported by barges but propulsion was achieved by rails. The details were still being worked out when the Deputy Chief of the Future Launch Systems Study Office received a phone call from Barry Schlenk, a representative of the Bucyrus-Erie Company, a mining equipment manufacturer. Schlenk had heard about NASA’s transport problems, and offering to help, he sent the Deputy Chief photographs of Bucyrus-Erie's steamshovel crawler used in the Kentucky coal fields. The vehicle seemed suited to NASA’s needs, especially its capability to level and balance a load on uneven terrain.
In late February the same year, a team of engineers from the Launch Operations Directorate (LOD) went to Paradise, a small town in Muhlenberg County, Kentucky, to see a Bucyrus-Erie crawler-shovel in action. The engineers watched in awe as the 2,700-metric-ton crawler picked up a load of coal and rocks and gracefully carried it away. The work platform was stabilized by hydraulic cylinders at the four corners, and it barely moved. Nearby, they saw another crawler-shovel under construction for the Peabody Coal Company, whose load-bearing capacity exceeded the expected weight of the Saturn C-5 and its support equipment.
A power shovel used in strip mining.
The LOD representatives were impressed by the crawler's potential, but when NASA moved towards closing the deal with Bucyrus-Erie as the company that will build the crawlers, the Marion Power Shovel Co. of Ohio protested. They urged NASA to use competitive bidding and award the contract to whichever company quoted the lowest price. Twenty two industrial firms sent representatives to a procurement conference, but only two submitted proposals—Marion for 8 million dollars, and Bucyrus-Erie for 11 million dollars.
Marion won the contract, but when the time came to select a competent manager for the project, they chose one not from their own company but from—of all firms—Bucyrus-Erie. His name was Philip Koehring. By the time Marion had finally completed the contract two years later, the price had risen above 11 million dollars.
Mobile Launcher Platform 3 is seen being carried away by a crawler-transporter. Photo: NASA
Marion built two crawler-transporters for NASA each measuring 131 feet by 114 feet and weighing 2,700 tons—as heavy as the load it was built to carry. Each vehicle has eight tracks, two on each corner; each track has 57 shoes, and each shoe weighs 900 kg. The engineers call them “Golden Slippers”. Using a laser guidance system, the crawler keeps the Mobile Launcher Platform level to within ten minutes of an arc while it negotiates grades of as much as five degrees. A separate laser docking system provides pinpoint accuracy when the crawler-transporter and Mobile Launch Platform are positioned in the Vehicle Assembly Building or at the launch pad. With the Space Shuttle aboard, the Crawler creeps at a maximum speed of about 1 mile per hour. Power is provided by 16 electric motors that are themselves powered by four V16 diesel engines.
For the safe movement of the crawler-transporter together with its precious cargo engineers designed a unique roadbed, as wide as an 8-lane freeway from the Vehicle Assembly Building to the launch pad, a distance of about 4 miles. Each of the dual trackways, separated by a median strip, consisted of a foundation of compacted sand, followed by a meter-thick layer of crushed aggregate, topped by a blacktop sealer. The crawlerway could support loads in excess of 58,000 kilograms per square meter.
Space Shuttle Challenger is carried by a Crawler-transporter on the way to its launch pad. Photo: NASA
The crawler-transporters are unique machines. They are the world's largest land transport vehicles, and since 1965 these two crawlers nicknamed “Hans” and “Franz”, have carried everything from the Saturn V rockets during the Apollo missions, to the Skylab and Apollo–Soyuz programs. After the Moon landing and Skylab programs ended, the crawlers continued their work, taking space shuttles to their launch pads for 30 years. In the coming years, NASA expects this monstrous vehicles to serve the Artemis program, that’s going to send the first woman and the next man to the moon. The crawler-transporter will most likely also carry the Space Launch System (SLS) rocket that could one day put humans on Mars.
Photo: NASA
Photo: NASA
Space Shuttle Discovery makes its way up the 5 percent grade to the hardstand of Launch Pad 39B. Photo: NASA
References:
# A Trip by Barge or a Trip by Rail?, NASA
# The Crawler Makes Its Debut, NASA
# The Crawler – Transporter, NASA
# Building a New Kind of Road, NASA
# Wikipedia
Comments
Post a Comment