Shuttle Training Aircraft

The Shuttle Training Aircraft (STA) was a NASA training vehicle that duplicated 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.

Development
The aircraft's exterior was modified to withstand the high aerodynamic forces incurred during training sorties. A redesigned cockpit provided a high-fidelity simulation of the Shuttle Orbiter's controls and pilot vantage point; even the seats were fitted in the same position as those in the Space Shuttle.

Operational history
Early program

Only had 2 aircraft. This was in the late 1977 to 1985

The exceptional engineers and managers that achieved program success were Stuart Law and Charles "Chuck" Coindreau. The original contractor handling the aircraft was Ford Aerospace and Communications Corporation. These first aircraft were based at Ellington Field near Clear Lake City, TX and managerially attached to Johnson Space Center. They flew sorties at Edwards Air Force Base, site of first Shuttle Landing, as well as White Sands, NM and Cape Canaveral, FL

Their purpose was to train the astronauts to land the shuttle by giving them a high fidelity eyeball view and seat of the pants feel that they would experience when flying the shuttle for landing. The mission was successful.

There were 6-hours of VHS or Betamax video presentations that explained the full operation of the aircraft. These were presented by the program manager, Stuart Law. In short, by 2016 standards the concept could be reprogrammable to be a hi-fidelity trainer for any commercial and some military airframe.

The original concept was proposed in the mid to late 1970's. In 1980 the proposal to upgrade the Mono-HUD to a full HUD display system required the addition of a second computer to the aircraft. It also required additional personnel. That was when I was hired.

There were many modifications to the airframe, especially the control surfaces.

The original Flight control system was a Sperry Flight Systems 1819B with all of the associated peripheral ATR boxes that became all too familiar. The Parallel Processor system added an Rolm1666B mini-computer.

These computers were mini's operating at 10 MHz clock speed, multi-clock machine cycle, and utilizing magnetic core memory. Mass storage was a 9-track Reel-to-Reel deck.

In this model only the left seat was a Fly-By-Wire system. The right seat had standard G-II control.

These two totally dis-similar architecture machines were interfaced to form a true asymmetrical dual parallel processing system.

This development led to the development of the Advanced Digital Avionics System (ADAS)which could be populated with a total of 16 parallel processors. Two of the original processors were custom Sperry 1819 based microprocessors. 14 were to be populated with Motorola 68010 processor card in a Sperry ATR form factor card, but VME protocols.

The contract was awarded to another contract after the JSC Consolidated Contract was awarded.

Below is after my time and looks like they continued on.

The four STAs were normally located at the NASA Forward Operating Location in El Paso, Texas and rotated through Ellington Field (Houston, Texas) for maintenance. The STA was also used at Kennedy Space Center in Florida. It was 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.

Flight profile
The STA was particularly critical for Shuttle pilots in training because the Orbiter lacked 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 was 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 37000 ft, the main landing gear was lowered (the nose gear stayed retracted due to wind load constraints) and engine thrust was reversed. Its flaps could deflect upwards to decrease lift as well as downwards to increase lift.

Covers were placed on the left hand cockpit windows to provide the same view as from a Shuttle cockpit, and the left-hand pilot's seat was fitted with the same controls as a Shuttle. The STA's normal flight controls were moved to the right, where the instructor sat. Both seat positions had a head-up display (HUD).

In a normal exercise, the pilot descended to 20000 ft at an airspeed of 280 kn, 15 mi from the landing target. The pilot then rolled the STA at 12000 ft, 7 mi from landing. The nose of the aircraft was then dropped to increase speed to 300 kn, descending at a 20-degree angle on the outer glide slope (OGS). The outer glide slope aiming point was 7500 ft short of the runway threshold, and used PAPIs for visual guidance in addition to the MLS system. At 2000 ft the guidance system changed to pre-flare and shortly after, at 1700 ft, the pilot started the flare maneuver to gradually reduce the descent angle and transition to the inner glide slope (IGS) which was 1.5 degrees from 300 ft onwards, using a "ball-bar" system for visual guidance. The shuttle landing gear release was simulated at 300 ft above the ground, since the STA main gear remained down for the whole simulation. The nose gear of the STA was lowered at 150 ft AGL in case of an inadvertent touchdown with the runway surface.

If the speed was correct, a green light on the instrument panel simulated shuttle landing when the pilot's eyes were 32 ft above the runway. This was the exact position that the pilot's head would be in during an actual landing. In the exercise, the STA was still flying 20 ft above the ground. The instructor pilot deselected the simulation mode, stowed the thrust reversers, and the instructor executed a go-around, never actually landing the aircraft (on training approaches).

Avionics
A sophisticated computer system installed on board the STA simulated the flight dynamics of the orbiter with nearly perfect accuracy. The STA's highly realistic simulation of the orbiter was not limited to handling characteristics, but also implemented the shuttle control interfaces for the pilot.

An onboard computer called the Advanced Digital Avionics System (ADAS) controlled the Direct Lift Control (DLC) and the in-flight reverse thrust during Simulation Mode.

Every shuttle commander practiced at least 1,000 landings in this manner, as had each mission's shuttle pilot.

List of Shuttle Training Aircraft
Four Gulfstream II aircraft constituted the current STA fleet, although other Gulfstream II aircraft, lacking STA capabilities, are still used by NASA for personnel transport purposes. Although the majority of the fleet had markings similar to those pictured above, paint schemes do vary slightly across aircraft. Current STA tail numbers are:


 * N944NA (sn144)
 * N945NA (sn118) (Currently at Birmingham–Shuttlesworth International Airport with plans to permanently locate to U.S. Space & Rocket Center )
 * N946NA (sn146) (On September 21, 2011, this aircraft became a permanent display at the Texas Air & Space Museum in Amarillo, Texas. )
 * N947NA (sn147)

On August 22, 2011, NASA announced that all four Shuttle Training Aircraft would be retired at various NASA facilities around the country, with N944 retiring at the Dryden Flight Research Center.

Other uses
In the event NASA's T-38 Talons were not available, the STAs were used for transporting shuttle crew members between major sites, namely from Johnson Space Center in Houston to Kennedy Space Center in Cape Canaveral, Florida.

Planned use of the 737 as the STA
During the early phases of the Shuttle program, NASA originally considered using the Boeing 737 airliner as the basis for the STA, but rejected it due to cost and opted for the less-expensive Gulfstream II.