This page is derived from a presentation given at the Arlington Composite Squadron meeting on 16 May 2012.
Goals for the presentation:
- Talk about the Space Shuttle Discovery’s arrival at the Smithsonian Institution
- Understand the unique features of the Shuttle Carrier Aircraft and its role in the Space Shuttle Program
- Discuss the functions of the Shuttle Training Aircraft and the T-38 and their contributions to the Space Shuttle Program
Discovery Arriving at her New Home
I had the privilege of being present at the National Air and Space Museum’s Udvar-Hazy Center to witness the arrival of Space Shuttle Discovery. Here is one of the pictures I took during its second pass of the museum.
There are some interesting features in the picture that are shown in the annotated version below.
You can see Discovery with its aerodynamic tailcone mounted on top of NASA’s last Shuttle Carrier Aircraft (N905NA). You can see the extra vertical stabilizers on the modified Boeing 747-100. Also, at the lower right there is one of the two T-38 chase planes that provided an escort during the flight up from the Kennedy Space Center.
The video below shows the final approach to Washington Dulles International Airport. There is also a gallery of photos of the fly-by.
Shuttle Carrier Aircraft
The following information on the Shuttle Carrier Aircraft can be found on the NASA web site at the following URL:
NASA used two modified Boeing 747 jetliners, originally manufactured for commercial use, as Space Shuttle Carrier Aircraft (SCA). One is a 747-100 model, while the other is designated a 747-100SR (short range). The two aircraft are identical in appearance and in their performance as Shuttle Carrier Aircraft. The 747 series of aircraft are four-engine intercontinental-range swept-wing “jumbo jets” that entered commercial service in 1969. The SCAs are used to ferry space shuttle orbiters from landing sites back to the launch complex at the Kennedy Space Center, and also to and from other locations too distant for the orbiters to be delivered by ground transportation. The orbiters are placed atop the SCAs by Mate-Demate Devices, large gantry-like structures which hoist the orbiters off the ground for post-flight servicing, and then mate them with the SCAs for ferry flights.
Features which distinguish the two SCAs from standard 747 jetliners are:
- Three struts, with associated interior structural strengthening, protruding from the top of the fuselage (two aft, one forward) on which the orbiter is attached
- Two additional vertical stabilizers, one on each end of the standard horizontal stabilizer, to enhance directional stability
- Removal of all interior furnishings and equipment aft of the forward No. 1 doors
- Instrumentation used by SCA flight crews and engineers to monitor orbiter electrical loads during the ferry flights and also during pre- and post-ferry flight operations.
The Two Shuttle Carrier Aircraft
NASA 905 was the first SCA. It was obtained from American Airlines in 1974. Shortly after it was accepted by NASA it was flown in a series of wake vortex research flights at the Dryden Flight Research Center in a study to seek ways of reducing turbulence produced by large aircraft. Pilots flying as much as several miles behind large aircraft have encountered wake turbulence that have caused control problems. The NASA study helped the Federal Aviation Administration modify flight procedures for commercial aircraft during airport approaches and departures.
Following the wake vortex studies, NASA 905 was modified by Boeing to its present SCA configuration and the aircraft was returned to Dryden for its role in the 1977 Space Shuttle Approach and Landing Tests (ALT). This series of eight captive and five free flights with the orbiter prototype Enterprise, in addition to ground taxi tests, validated the aircraft’s performance as an SCA, in addition to verifying the glide and landing characteristics of the orbiter configuration — paving the way for orbital flights.
A flight crew escape system, consisting of an exit tunnel extending from the flight deck to a hatch in the bottom of the fuselage, was installed during the modifications. The system also included a pyrotechnic system to activate the hatch release and cabin window release mechanisms. The flight crew escape system was removed from the NASA 905 following the successful completion of the ALT program.
NASA 905 was the only SCA used by the space shuttle program until November 1990, when NASA 911 was delivered as an SCA. Along with ferrying Enterprise and the flight-rated orbiters between the launch and landing sites and other locations, NASA 905 also ferried Enterprise to Europe for display in England and at the Paris Air Show.
The second SCA was designated NASA 911. It was obtained by NASA from Japan Airlines (JAL) in 1989. It was also modified by Boeing Corporation. It was delivered to NASA 20 November 1990.
The information shown below was derived from “The World’s Greatest Piggy Back Ride” at http://www.nasa.gov/externalflash/shuttlecarrier/.
So, we have a very large commercial airplane and we put another large airplane (namely, a Shuttle Orbiter) right on top of it. It definitely has an impact on the aerodynamics and center of gravity! As you can see in the following pictures, most of the interior of the 747 was stripped out to save weight. (These photos can be found at http://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft.)
Where and How do you attach a Space Shuttle?
The first picture (also available at http://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft) shows one of the mount points on the top of the Shuttle Carrier Aircraft with some humor from NASA’s engineers. The second picture shows NASA’s Mate-Demate Device (MDD) used to mount or unmount an orbiter from the SCA. In cases where an MDD is not available, a two-crane approach is used. Both are shown in this picture (and are available on the NASA web site).
To adjust the center of gravity of the combined aircraft, the SCA was loaded with pellets of pig iron. They used around 1,710 pounds in the first class section and another 7,000 pounds in the cargo hold.
Approach and Landing Tests
We are most familiar with the Shuttle Carrier Aircraft moving orbiters from place to place – from the California desert back to Kennedy Space Center following a mission, and now flying the orbiters to their new museum homes. However, the original purpose of the aircraft was to test the gliding capabilities of the first orbiter, Enterprise. A series of five gliding tests were conducted where the orbiter was released from the top of the SCA and simulated a gliding return from orbit. NBC covered the first flight on live television in 1977, shown below.
The T-38 and the Shuttle Training Aircraft
I don’t want to leave out these other aircraft that were so important to the success of the Space Shuttle program. NASA uses T-38 trainers as chase planes (you can see them in the video from 1977 as well as in Discovery‘s arrival at Dulles Airport) as well as for astronaut pilot proficiency and transport.
Also, NASA has a Gulfstream II aircraft that has been modified to simulate the cockpit of the orbiter as well as its inflight characteristics. Since there weren’t a lot of real orbiters available for training, Shuttle commanders and pilots have logged thousands of simulated landings using this Gulfstream.
- Go see the Discovery at the Udvar-Hazy Center!
- It took a lot more than just the Shuttle Orbiter to make the system work
- Shuttle Carrier Aircraft to get the orbiters where they needed to be
- T-38s as chase planes and astronaut training/transport
- Shuttle Training Aircraft for landing proficiency