Shuttle Training Aircraft
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The Shuttle Training Aircraft (STA) is a NASA training vehicle that duplicates the Space Shuttle's approach profile and handling qualities, allowing astronaut pilots to simulate Shuttle landings under controlled conditions before attempting the task onboard the orbiter. It is a modified Gulfstream II business jet originally manufactured by Grumman Aerospace, a unit of U.S. defense contractor General Dynamics.
The aircraft has been redesigned such that the skin can withstand the threshold of aerodynamic forces during each training sortie or 'exercise'. The interior has been redesigned so as to simulate the Shuttle Orbiter's cockpit and the seats are fitted in the exact position as the seats in the Space Shuttle.
The STAs are located at Ellington Field, approximately 2-3 miles from Johnson Space Center in Houston, Texas.[1]
The STA is particularly critical for Shuttle pilots in training because the Orbiter lacks the atmospheric engines that would allow the craft to "try again" after a poor approach. After re-entry, the Shuttle is essentially a very heavy glider (it is sometimes referred to as a 'flying brick'), and as such has only one chance to land.
In order to match the descent rate and drag profile of the real Shuttle, the landing gear is lowered and engine thrust is reversed. Its flaps deflect upwards to decrease lift as well as downwards to increase lift. Covers are placed on the windows to provide the same view as from a Shuttle cockpit, and the left-hand pilot's seat is fitted with the same controls as a Shuttle. The STA's normal flight controls are moved to the right, where the instructor sits. Both seat positions have a Head Up Display (HUD).
To simulate the orbiter's flight dynamics, an integrated onboard computer system is installed which enables the flight dynamics of the orbiter with 100% indistinguishable accuracy. The STA provides pilots with a realistic simulation of the Orbiter with the following:
- cockpit
- motion
- visual cues, and [2]
- handling qualities.
To simulate the events in the STA cockpit at 35,000 feet, and is abeam the intended point of landing, the instructor pilot performs the following:
- lowers the landing gear
- selects reverse thrust, and
- activates simulation mode, activating the shuttle pilot's controls.
The pilot then navigates the STA around a heading alignment circle, a maneuver which aligns the shuttle's (or training aircraft's) flight path with the landing runway.
An onboard computer called the Advanced Digital Avionics System (ADAS) controls the Direct Lift Control (DLC) and the in-flight reverse thrust during Simulation Mode. In a normal exercise, the pilot descends to 20,000 feet at an airspeed of 280 knots, 15 miles from the landing target. The pilot then rolls the STA at 12,000 feet, 7 miles from landing. The nose is then dropped to increase speed to 300 knots, descending at a 20 degree angle. At 1,750 feet the pilot flares to reduce the descent angle to a more gradual 3 degrees. The shuttle landing gear is released at 300 feet above the ground surface. This is simulated completely by computer as the STA's gear has been down for the entire exercise.
If the speed is correct, a green light on the instrument panel simulates shuttle landing when the pilot's eyes are 32 feet above the runway. This is the exact position that the pilot's head would be in during actual landing. In the exercise, the STA is still flying several feet in the air. The instructor pilot deselects the simulation mode, normal power is restored, and the instructor flies around the runway, never actually landing the aircraft. Every Shuttle Commander has practiced at least 900 landings in this manner. The Pilot performs the exact training as the Commander. [1]
There are 7 Gulfstream II aircraft in the current STA fleet. While most of these are marked as pictured above, a few have varying paint schemes. Current STA tail numbers are:
- N944NA
- N945NA
- N946NA
- N947NA
- N948NA
- N949NA
- N950NA
In the event NASA's T-38 Talons are not in use, the STAs are used for transporting crewmembers between major sites, namely from Johnson Space Center in Houston to Kennedy Space Center in Cape Canaveral, Florida.
