Shuttle Training Aircraft
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|C-11A Shuttle Training Aircraft|
|Developed from||Grumman Gulfstream II|
The Shuttle Training Aircraft (STA) is a NASA training vehicle that duplicates the Space Shuttle's approach profile and handling qualities, allowing Space Shuttle pilots to simulate Shuttle landings under controlled conditions before attempting the task on board the orbiter.
The aircraft's exterior has been modified to withstand the high aerodynamic forces incurred during training sorties. A redesigned cockpit provides a high-fidelity simulation of the Shuttle Orbiter's controls and pilot vantage point; even the seats are fitted in the same position as those in the Space Shuttle.
The four STAs are normally located at the NASA Forward Operating Location in El Paso, Texas and rotated through Ellington Field (Houston, Texas) for maintenance. The STA is also used at Kennedy Space Center in Florida. It is primarily flown by astronauts practicing landings at the Shuttle Landing Facility and White Sands Space Harbor as well as to assess weather conditions prior to Space Shuttle launches and landings.
On December 3, 2003, a NASA Gulfstream II shuttle Training Aircraft (STA) was flying a series of simulated shuttle landings to the Kennedy Space Center shuttle landing facility. On board the aircraft was an unidentified NASA astronaut pilot and two training personnel. The aircraft was on final approach at 13,000 feet when onboard instruments indicated a malfunction on one of the jet engine thrust reversers. The aircraft landed safely. A post-landing inspection showed that one of the 585-pound, 4-foot-wide, 5-foot-long thrust reversers had fallen off the aircraft. Divers later found the thrust reverser on the bottom of the nearby Banana River. An investigation showed that a bolt failed, releasing the part from the aircraft.
The STA was particularly critical for Shuttle pilots in training because the Orbiter lacks the atmospheric engines that would allow the craft to "go around" after a poor approach. After re-entry, the Shuttle was a very heavy glider (it is sometimes referred to as a 'flying brick') and as such had only one chance to land.
In order to match the descent rate and drag profile of the real Shuttle at 37,000 feet (11,300 m), the main landing gear was lowered (the nose gear stayed retracted due to wind load constraints) and engine thrust is reversed. Its flaps may deflect upwards to decrease lift as well as downwards to increase lift.
Covers are placed on the left hand cockpit 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).
In a normal exercise, the pilot descends to 20,000 feet (6,000 m) at an airspeed of 280 knots (519 km/h), 15 miles (24 km) from the landing target. The pilot then rolls the STA at 12,000 feet (3,700 m), 7 miles (11 km) from landing. The nose of the aircraft is then dropped to increase speed to 300 knots (560 km/h), descending at a 20-degree angle on the Outer Glide Slope (OGS). The Outer Glide Slope aiming point is 7500ft short of the runway threshold, and uses PAPI's for visual guidance in addition to the MLS system. At 2000ft the guidance system changes to pre-flare and shortly after, at 1,700 feet (518 m), the pilot starts the flare maneouver to gradually reduce the descent angle and transition to the Inner Glide Slope (IGS) which is 1.5 degrees from 300ft onwards, using a "Ball-bar" system for visual guidance. The shuttle landing gear release is simulated at 300 feet (90 m) above the ground surface, since the STA main gear has been down for the whole simulation. The nose gear of the STA is lowered at 150 ft (46 m) AGL in case of an inadvertent touchdown with the runway surface.
If the speed is correct, a green light on the instrument panel simulates shuttle landing when the pilot's eyes are 32 feet (10 m) 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 20 feet (6 m) above the ground. The instructor pilot deselects the simulation mode, stows the thrust reversers, and the instructor executes a go-around, never actually landing the aircraft (on training approaches).
A sophisticated computer system installed on board the STA simulates the flight dynamics of the orbiter with nearly perfect accuracy. The STA's highly realistic simulation of the Orbiter is not limited to handling characteristics, but also implements the shuttle control interfaces for the pilot.
The pilot then navigates the STA around a heading alignment cone (HAC), 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.
Every Shuttle Commander has practiced at least 1000 landings in this manner, as has each mission's Shuttle Pilot.
List of Shuttle Training Aircraft
Four Gulfstream II aircraft constitute the current STA fleet, although other Gulfstream II aircraft, lacking STA capabilities, are also used by NASA for personnel transport purposes. Although the majority of the fleet have markings similar to those pictured above, paint schemes do vary slightly across aircraft. Current STA tail numbers are:
- N944NA (sn144)
- N945NA (sn118)
- N946NA (sn146) (On September 21, 2011, this aircraft became a permanent display at the Texas Air & Space Museum in Amarillo, Texas.)
- N947NA (sn147)
In the event NASA's T-38 Talons are not available, 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.
- NASA - Test Drive: Shuttle Training Aircraft Preps Astronauts for Landing
- "NASA ties bolt to training scare", Florida Today newspaper (article reprinted on the International Aviation Safety Association website), Feb 7, 2004
- "NASA Jet Sheds Parts Over Florida", AVweb website, February 9, 2004
- IIS Corp. Shuttle Training Aircraft
- NASA Space Shuttle Trainer Retires In Amarillo
- NASA aircraft flown by Rick Husband calls Amarillo 'home'
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