Senin, 18 Maret 2013


Simulation & Training

The next advance in training for strike and fighter pilots will be a combined flight simulator and centrifuge, adding the feel of realistic highg-forces to the cues from a wide-field-of-view visual system, as the pilot maneuvers his aircraft. 

The benefits for training pilots in air combat maneuvers, missile avoidance, recovery of aircraft that have ``departed'' from controlled flight, and for tactics innovation could be huge--increasing pilots' tactical capability and survivability. The new device also could help close the gap between the growing g-capability of modern fighter aircraft and that of the pilot. 

ENVIRONMENTAL TECTONICS Corp. (ETC) of Southampton, Pa., developed the top-of-the-line G-FET II dynamic flight simulator. The pilot's cockpit and visual system is inside a gondola on the end of a 25-ft. rotating arm. Gimbals allow the gondola to actively move in roll and pitch. Accurate control of the direction of the g-vector (g-pointing) and the ability to create rapid g-onset and sustained gs distinguish it from earlier centrifuge systems. 

The G-FET II can accelerate very quickly, with rates up to 15g per sec.--more than a pilot can withstand without becoming incapacitated from g-induced loss of consciousness (g-loc)--and can maintain 25g. Modern fighters can sustain more than 9g at onset rates of more than 9g/sec. during air combat maneuvering, which exceeds pilots' capability. Learning to fly and operate systems under sustained g-forces is vital to getting the most out of aircraft weapon systems. 

Accurately reproducing the ``g feel'' of a maneuvering aircraft stems from 30 years of development at ETC's Aeromedical Training Center and a cooperative effort with the Air Force Institute of Technology. Acceleration in the X, Y and Z axes has to be highly synchronized with the pilot's flight control inputs and the wide-field-of-view visual system. The ETC system continuously orients the gondola through the multi-axis gimbals to respond to pilot input. 

If the pilot can perceive any delay or ``artifacts''--responses that don't ``feel'' right--realism suffers. The gondola is designed so the pilot's ear is at the center of rotation to minimize extraneous vestibular sensory artifacts. A software model called the Inverse Dynamic Controller blends the inputs to give the high-fidelity response that makes G-FET II feel like a real aircraft, according to ETC. 

A training facility could buy a number of different aircraft cockpits that can be installed in the gondola in just 60 min., according to the company. Each cockpit has its own 120 X 50-deg. wide-field-of-view vision system. In one of ETC's concepts, an uninstalled cockpit could function as a stationary trainer, either linked to others or operating independently. For installation into the gondola, a cockpit would be lifted by an overhead hoist and lowered into place. A pilot enters the cockpit via stairs that drop down from the bottom of the gondola. 

ALTHOUGH FLIGHT physiologists have used centrifuges for years, their value for pilot training has been well established only since the 1970s, according to ETC. The real impetus for high-g training was the advent of modern nimble aircraft that place pilots more at risk of g-loc.
Sustained gs were not a problem with earlier aircraft. The Vietnam era A-7 could pull 7g, but only for a short time, because the airspeed bled off, and the g-forces came off before the pilots had a large g-loc problem. But USAF's F-15 and F-16 and the Navy's F/A-18 can hold 6g in a turn until they run out of fuel, according to Al Hall. He is the lead engineer for the training system division at the Navy Air Warfare Center at Lemoore, Calif. 

The Navy has an earlier version of ETC's dynamic flight simulator, called a centrifuge flight environment trainer, at Lemoore. Hall said it is being used to teach F/A-18 and F-14 pilots straining and breathing techniques to resist the effects of high-g. 

Following 2 hr. of classroom time, where pilots learn and practice the g-tolerance techniques, they put theory into practice by going through a series of increasing and decreasing g-profiles during a 15-min. simulator ride. ``Pilots are reluctant to get in, but they walk out with a different attitude,'' Hall said. At the moment, training is slated for only once in a career. The Air Force has a similar ETC simulator, but with a little shorter arm, for pilot training at Holloman AFB, N.M. 

The two main hazards for pilots are rapid g-onset and sustained g. Older centrifuges could sustain high g-forces but accelerated slowly. At Lemoore, as one part of their training, pilots are exposed to an onset of 6g in 1 sec., ``which gives them a real kick in the pants,'' Hall said. 

At the moment, the devices at Lemoore and Holloman are the only multi-axis trainers that the U.S. owns. Singapore and Japan currently each have an ETC high-end centrifuge capable of g-pointing, but do not have the modular cockpit or tactical flight simulator. As a result, the full training capability envisioned by ETC is still ``around the corner.'' That device, called the TFS-400, will sell for about $35 million.

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