Its Been A Long Time, Getting From There To Here



The great bird will take its first flight upon the back of the great swan, filling the world with wonder and all writings with renown, and bringing eternal glory to the nest where it was born.



- Leonardo da Vinci (1452-1519), Notebooks, Volume 1





The property of Leonardo da Vinci gained fulfillment on February 18, 1977 as the great bird made its first flight on the back of the great swan. Their appearance spoke of power, the orbiter white in its Styrofoam, the 747 looking silvery, the word American faded but visible clearly on its side. If the event did not fill all writings with renown, it at least merited two pages of text in Aviation Week, along with four pages of photos.



- Thomas A. Heppenheimer, Development of the Space Shuttle 1972-1981





(Based on texts written by Thomas A. Heppenheimer, Dennis R. Jenkins and Jacques van Oene)





ENTER ENTERPRISE



When NASA decided at the end of the Apollo Moon program that it needed something new for future space travel, various concepts were proposed  and from those emerged the Space Shuttle. North American Rockwell was given the prime contract in July 1972 to build five Space Shuttle orbiters, the first one being a prototype to be used for glide and ground tests. Work to build the first shuttle orbiter, OV-101, began on June 4, 1974, at the Rockwells Air Force Plant 42, Site 1, in Palmdale, California. Final assembly of all the components that came from various subcontractors started in March 1975. On August 25, 1975, the final assembly was complete.



At Christmastime 1975, readers of the trade journal Astronautics & Aeronautics saw an arresting color photo on the cover of the January 1976 issue. It showed what was unmistakably an airplane in final assembly within a hangar  and which equally unmistakably was a Space Shuttle orbiter. Space Shuttle 1976, read the covers caption; Into Mainstream Development. The wings and vertical fin were in place, along with much of the fuselage. This was OV-101, which later that year  as a result of the mail campaign organized by fans of the popular Star Trek TV series was to receive the name Enterprise.



The Trekkers had only forgotten one thing  Enterprise was not built to fly in space like the real starship. But nonetheless she had a useful career in flight and ground test. In September 1976, amid considerable ceremony, she was rolled out for public display, thus showing dramatically that the shuttle program indeed was building hardware.



During the summer of 1976, shortly before the rollout, OV-101 had served as the test vehicle for the Horizontal Ground Vibration Test, conducted in Palmdale. Earlier vibration testing had used an accurate structural model, at one-quarter scale, with water in its External Tank to simulate liquid oxygen and air replacing the very lightweight liquid hydrogen. The new tests gave engineers their first opportunity to verify their mathematical models by taking data on the structural dynamics of an actual flight orbiter.



Although OV-101 was not identical to the configuration planned for OV-102, the differences were well understood and accounted for in the model. For instance, Enterprise did not have provisions for mounting real OMS pods, but used structural boilerplate replicas, and the vertical stabilizer was built-up using skin and stringers as opposed to the integrally machined structure of OV-102. The payload installed in the orbiter during the HGVT was the 10,000-pound Development Flight Instrumentation package that would be used during the atmospheric flight tests.



There were two test configurations, one with the orbiter supported in a free-free condition to simulate reentry and landing, and the other with the orbiter rigidly attached to the ground at its External Tank supports to represent the configuration during ascent. Tests were also conducted with the payload bay doors opened to simulate an on-orbit configuration. Ferry locks were used to secure the aerodynamic control surfaces during testing, mainly to prevent unexpected damage. The tests vibrated this vehicle at frequencies from 0.5 to 50 hertz, determining natural or resonant frequencies and their damping. Other measurements determined frequency response at the locations of sensors used for guidance and control. Following the completion of the tests, minor modifications were made to the vehicle prior to the public rollout.



The following year Enterprise would be used for Approach and Landing Tests at Edwards Air Force Base, California. It would be flown piggyback atop the SCA Boeing 747, later to be used to ferry orbiters from coast to coast, and released, gliding back to a landing as if returning from space. Following the ALT flights, OV-101 continued to find useful roles, first in structural tests and then in exercising the shuttles launch facilities, and for a short while even in diplomatic service.





NOT MUCH OF A STARSHIP



She was not much of a starship. By comparison with later operational orbiters, Enterprise was little more than an aluminum shell swathed in Styrofoam. She lacked all propulsion; the main engines, orbit-maneuvering engines, and attitude-control thrusters were dummies. In place of her thermal protection, blocks of polyurethane foam covered the surface. The nose and wing leading edges, which would be of temperature-resistant carbon-carbon composite, instead were of glass fiber. Enterprise had fuel cells for onboard power, but these held their hydrogen and oxygen as gases in high-pressure tanks, not as liquids in cryogenic dewars. Hence they could not run for very long.



The flight deck lacked many instruments and displays that would be needed for ascent to orbit. Most of the navigation, guidance, and propulsion controls were missing, along with the star tracker controls. The heads-up displays were not installed, nor were all then panels, switches, and indicators for the ET and SRB systems. A small amount of additional instrumentation was added just below the left display electronics unit for the air data system installed on the long flight test boom on the nose.



Three cameras recorded the pilots actions and Lockheed SR-71 zero-zero ejection seats were provided in the vent escape was necessary. Two blow-out panels were installed above the pilots to facilitate ejection, or rapid egress on the ground. The two windows looking from the aft flight deck into the payload bay were absent, covered by aluminum panels, as were the overhead rendezvous windows. Aluminum braces were installed where the middeck airlock should have been.



The crew quarters needed such amenities as the galley, the waste management system, and middeck lockers. The payload bay was not fitted out to accommodate its payloads, while the bays doors had no hydraulics and no radiators to get rid of waste heat. In flight, the crew was to lower the landing gear by triggering explosive bolts and letting gravity do the rest. But this gear lacked a hydraulic system for retraction.



Even so, Enterprise looked like a Space Shuttle and she held more than outward show. For the moment, she was well-suited to do her limited purpose. After the second rollout on September 18, 1976, where she had gone on display at an open house for Rockwell employees, she returned to her hangar for checks of her onboard systems (yes, she did have them).

