On April 14, 1981, more than 300,000 aerospace aficionados
assembled on the barren east shore of Rogers Dry Lake at Edwards Air
Force Base to witness a first in aerospace history. Some seven miles
away, on the ramp at NASA’s Dryden Flight Research Center, another 20,000
distinguished visitors and NASA employees gathered to behold
the same event.
They were rewarded that sunny spring morning, as the
double-crack of a powerful sonic boom resounded across the desert,
heralding the coming conclusion of the first Space Shuttle orbital
mission. Moments later, astronauts John Young and Robert Crippen
guided the shuttle Columbia onto lakebed runway 23, proving beyond
shadow of doubt that a spacecraft could return to Earth safely with a
powerless but controlled airplane-style landing.
But NASA’s flight research outpost in Southern California’s high
desert had made numerous contributions to the Space Shuttle program
before that historic first landing, and has made many more since.
Even today, 20 years after that epochal event, the Dryden Flight
Research Center plays a significant though often overlooked role in
America’s space flight program. Dryden’s major past and present
contributions to the Space Shuttle program include:
- 1960s: Development of space-rated control, environmental and
navigation systems – The X-15 hypersonic rocket plane program
contributed directly to the Space Shuttle program through its
pioneering development of reaction control systems for attitude
control in space, including transition from aerodynamic controls to
reaction controls and back again. Other X-15 contributions to the
Shuttle program included the first practical full-pressure suit for
pilot protection in space, inertial flight data systems in a high
dynamic pressure space environment, demonstration of a pilot’s
ability to function in a weightless environment, and development of
improved high-temperature seals and lubricants. - 1960s-1970s: Energy Management Techniques for Re-entry and Landing
– The X-15 rocket plane and the lifting bodies flown at Dryden made a
major contribution to the development of energy management and
unpowered landing techniques for the Space Shuttles. The X-15 and the
wingless lifting bodies demonstrated that it was feasible for an
aerospace vehicle with a low lift-to-drag ratio to make a safe,
controlled landing without power. - 1970s: The F-8 Digital Fly-By-Wire program – Another Dryden
contribution to shuttle development was in the testing of the flight
control computers later used on the shuttles. The IBM AP-101
computers were flight-validated during the second phase of the F-8
Digital Fly-By-Wire (DFBW) research program before they were used on
the shuttles. - 1970s: Shuttle Carrier Aircraft — Once the decision had been made
to eliminate jet engines for the shuttles’ approach and landing at
Edwards, a means of ferrying the shuttles back to the launch site had
to be devised. Dryden engineers proposed a variation of the
tried-and-true “mothership” concept that had been used for lifting the X-1
through X-15 and the lifting bodies to launch altitude; the modified Boeing747
Shuttle Carrier Aircraft evolved from their recommendation. - 1970s: YF-12 High-Speed Research – During the high-speed,
high-altitude flight research program conducted with the Lockheed
YF-12, Dryden engineers developed a central airborne performance
analyzer which monitored various aircraft systems, detected problems
and provided that data to the pilot, as well as to engineers and
maintenance personnel on the ground. The analyzer became the
forerunner of vehicle health monitoring systems used on the space
shuttles and a variety of today’s aircraft. - 1977: Shuttle Approach and Landing Tests — Dryden hosted and
helped conduct the Approach and Landing Tests (ALT) of the prototype
shuttle orbiter Enterprise at Edwards AFB in 1977. The ALT validated
the concept of carrying the shuttle on the 747 Shuttle Carrier
Aircraft during captive-carry flights and of landing the shuttle
without power during five free flights. - 1977: Resolving Pilot-Induced Oscillation problem — On the final
ALT flight, the pilot overcontrolled the Enterprise and it entered a
dangerous pilot induced oscillation (PIO)-a frequent phenomenon with
new digital fight control systems-just at touchdown on Edwards’ main
concrete runway. Subsequent flights with the F-8 DFBW and other
aircraft demonstrated that the problem with the shuttle flight
control system lay in a time delay that stimulated pilots to
over-control because their inputs to the flight control computer were
taking too long to go into effect. With their experience with digital
flight controls from the F-8 DFBW, Dryden engineers designed a PIO
suppression filter that solved the problem and was incorporated into
the shuttles’ flight control computers. - 1977-78, 1983-85: Booster Recovery System – Dryden’s NB-52B
mothership made 31 test flights in a two-phase project to validate
the performance and reliability of the shuttle’s solid rocket booster
parachute recovery system. The parachutes are used to slow the
descent of the solid rocket booster casings once they have completed
their boost phase and separated from the shuttles’ external fuel
tank. - 1979-80: Structural Loads and Orbiter Handling Analysis – At
Johnson Space Center’s request, Dryden engineers conducted an
independent analysis of the shuttle design related to
aerothermal-induced structural loads and handling qualities prior to
its first space flight. Dryden’s analysis found the shuttle’s control
system was capable of compensating for uncertainties in the shuttle’s
flight characteristics, and verified the overall adequacy of the
design to accomplish re-entry from orbit and a safe landing on
Earth. - 1980s: Thermal Protection System Testing – Dryden research pilots
flew 60 missions in Dryden’s F-104 and F-15 aircraft to test space
shuttle thermal protection tiles under various aerodynamic load
conditions. The tests led to several changes to improve techniques
for bonding the tiles to the shuttles’ surfaces. - 1990: Shuttle Drag Parachute Tests – NASA Dryden’s venerable NB-52B
was used to help develop the drag parachute deployment system now
used during space shuttle landings. During a series of eight flight
tests in 1990, the modified bomber validated the initiation,
deployment, inflation and overall operation of the parachutes. The
drag chutes are deployed from the shuttles moments after touchdown,
reducing tire and brake wear and shortening the rollout distance on
the runway. - 1993-1995: Shuttle Tire and Brake Tests — NASA Dryden modified a
Convair 990 into a Landing Systems Research Aircraft in the mid-1990s
to test the shuttles’ tires and braking systems on a variety of
runway surfaces. These tests led to improvements in both the tires
and brakes, an increasing in the allowable crosswind landing limits
and resurfacing of the runway at the Kennedy Space Center’s Shuttle
Landing Facility which reduced shuttle tire wear by half. - 1981-Today: Primary/Alternate Landing Site – Dryden and the Edwards
complex was the primary space shuttle landing site for the first 12
years of the program, and has served as the backup alternate landing
site since then. Out of 102 shuttle missions completed to date, 47
have landed at Edwards, 54 at the Kennedy Space Center, and one at
the White Sands Missile Range in New Mexico. The most recent mission
to land at Edwards was STS-98, which saw the shuttle Atlantis land
here on Feb. 20, 2001. - 1981-Today: Shuttle Post-Flight Processing Capability — Dryden
maintains a full complement of equipment to support Space Shuttle
landing, recovery, post-flight processing and turnaround operations
to prepare the shuttles for their ferry flights back to the Florida
launch site when landings occur at Edwards AFB. One of NASA’s two
modified Boeing 747 Shuttle Carrier Aircraft is maintained on-site
for this purpose.
