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A Ride on the Shuttle Training
Aircraft
By Leslie Ringo
August 10, 1998
One of the simulations that I work on at the VMS (Vertical
Motion Simulator) is the Space Shuttle simulation. Astronauts fly out from
Houston, Texas twice a year to train for their missions on the VMS. The
Astronauts only use the VMS for the training of the last phase of their
shuttle mission, the landing and rollout phase. A typical run starts at
around 10,000 feet above the runway, and the run is considered completed
once the Shuttle has safely landed on the runway. The VMS is used for this
training since it can simulate the approach and landing with accurate cues
to the pilot.
The VMS is only one tool used to train the Astronauts
for the landing portion of a space mission. Another training vehicle used
by the Astronauts is called the Shuttle Training Aircraft or STA. The
STA started out as a Gulfstream business jet, but many engineering modifications
and a sophisticated flight computer allow this jet to fly as a Shuttle
would for the landing approach to a runway. I was given the opportunity
to be an observer on an STA orientation flight. This flight opened my
eyes to the different ways astronauts are trained compared to the VMS.
There are four Shuttle Training Aircraft available
at any one time. Sometimes they are used prior to shuttle launches or
landings to check weather conditions. For training purposes, my flight
started out at El Paso, Texas and all runway approaches were made to White
Sands, New Mexico. Inside the cockpit, the left seat was modified to have
only Shuttle instrumentation and controls for the astronaut. The right
seat was for the instructor pilot who flew with instruments and controls
you would find on a typical business jet. The flight simulation engineer
sat in the center jump seat. The flight simulation engineer was responsible
for setting up the next run. For all of the approaches, I stood behind
the flight simulation engineer to see what the astronaut might see on
a landing approach.
So what was a typical approach like on the STA? A
typical approach to a runway usually starts at around 16,000 feet. The
plane would then deploy the main landing gear and engine reverse thrusters.
This would create large amounts of drag that put the STA into an 18-20
degree dive to the runway. In comparison, a standard commercial airline
approach to a runway is between 2-3 degrees. When the aircraft is at 2,000
feet, the astronaut starts a fast pull up that generates forces 1.5 Š
2.0 times gravity, or what you would feel if you were in a swing. A "simulated
touchdown" actually occurs once the STA main gear has reached about 20
feet above the runway. This is considered a touchdown since the pilot
is at the same location he would be if he were in the actual Shuttle (see
figure). After the "touchdown", the instructor pilot exits the simulation
training run and climbs to set up for another run. Each astronaut completes
10 approaches for their training flight with the STA.
Several engineering observations were made during
these STA approaches. It clearly pointed out differences between the STA
and VMS. Since the STA does not actually land on the runway during a training
approach, it was obvious the VMS plays an important role for the rollout
phase. For a VMS simulation, we can easily blow tires, modify the height
of the nose landing gear, or fail the chute. With these failures, we can
successfully guarantee no damage an aircraft. ThatÕs the best thing about
a computer simulation, you can quickly reset to any Shuttle configuration
you desire.
Without a doubt, the STA orientation flight was both
exciting and very informative!
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