The system
The F-22 will be easy to fly, the manufacturers worked hard to achieve user-friendliness
in the handling qualities of the aircraft. The flight-control concept of "carefree
abandon" means that the pilot will never have to worry about losing control, over
stressing the aircraft, or getting anything but power. There are 20 controls with 63
functions on throttles and side stick, which enable the pilot to do everything hands on.
Unusually, canopy design was part of the cockpit team's task. There is no canopy bow
because of low-observability and pilot-vision requirements and the transparency is a
single piece of monolithic polycarbonate with no complex curves. Bird strike testing
revealed a problem when the canopy deflected and shattered the head-up display, display
supplier GEC-Marconi Avionics is developing a collapsible combiner which will still work
as a 600kt (1,100 km/h) blast shield. The canopy rotates down and translates forward to
lock. To jettison, the canopy is pushed back and lifted off by a rocket thruster at its
forward edge. The canopy does not fall but becomes a flying object and is weighted
asymmetrically to ensure that it diverges from the ejecting pilots' flight path.
Modifications to the Air Force's McDonnell Douglas ACES II zero-zero ejection seat (for
operation at speeds up to 1,100 km/h) in the F-22 include arm restraints and a fast-acting
drogue. As the seat moves up the rails, restraint nets encapsulate the pilot, and the
drogue is fired to deploy immediately the seat leaves the rails and before it can yaw.
This prevents injuries that can occur if the seat is off axis when the drogue deploys. The
seat is "electrified", with an electronic sequencing system, which can be tested
on the ground.
The F-22 is the first program to include development of the man-mounted life-support
system. The manufacturers wanted to be able to spend lots of time at high altitude and
high G without wearing the pilot out. The problem was that, to protect the pilot from
chemical/biological (CB) threats, he had to be wrapped in plastic. Therefore the pilot has
to have thermal protection. In addition, he needed more thermal protection in case he
ditched in the water. If you put CB gear, a cold-weather suit, G-suit, and thermal
protection on him, you'd be lucky to get into the aircraft, let alone enable him to fly or
fight, so they needed something different.
The F-22 life-support system integrates all critical components in one ensemble. In the
past, these elements would have been designed separately. Those components include the
on-board oxygen generation system (OBOGS); breathing regulator/anti-g system (BRAG);
chemical/biological (C/B)/cold-water immersion protection garment; upper pressure garment;
lower pressure garment; air-cooling garment; helmet and helmet-mounted systems including
C/B goggles and C/B hood; breathing mask; and hose system.
The gear
The resulting F-22 life-support system is divided into aircraft- and man-mounted pieces.
Normalair Garrett has developed an onboard oxygen-generating source to "...fit into a
small space with a peculiar shape." The UK manufacturer also developed a single
breathing regulator/anti-G valve, to provide positive-pressure breathing at high altitude
and high G. Man-mounted pieces include an air-cooling garment, produced by ILC of Dover,
Delaware. A dedicated line feeds conditioned air to the pilot, providing a temperature
range of 13-32°C. This is also going to be used by pilots on the Army's RAH-66 Comanche
helicopter. Over this goes the flight suit, designed by Boeing and British Columbia-based
META Research. M.E.T.A. Research has designed gear for the U.S. Coast Guard, Canadian
military forces, and commercial boaters and fishermen. Doubling as an immersion suit, as
well as providing protection against flames and a CB environment, the integrated suit will
meet with much higher pilot acceptance, Boeing says. Over the suit goes an upper pressure
garment, also CB-hardened, which provides counter pressure to assist breathing and
counteract G. The lower G garment incorporates a one-piece bladder for the legs and lower
torso. It is still mobile enough so the pilots can fight, otherwise it would have had to
be a like a full pressure suit like those used on the SR-71 says Boeing.
The helmet
The helmet now used by Air Force pilots, the HGU-55/P, meets all the prerequisites for the
service's current fighters and bombers. However, for use in the F-22, it falls short in
some areas. Wind forces seen during ejections, that occur at aircraft cruising speeds at
450 knots estimated air speed, cause the HGU-55/P to separate from the pilot's head thus
leaving the pilot unprotected. The new helmet is built to remain on the pilot at 600 knots
EAS and operations at high altitudes. The lightweight, low-lift helmet has been developed
by UK-based Helmet Systems (Alpha). The Alpha HGU-86/P tested being approximately 30
percent lighter than existing systems. The HGU-86/P fits 99 percent of the Air Force's
male flying population, and is being evaluated for the female flying population. Because
the new helmet is lighter, with a more comfortable fit than the older one, it can be worn
for longer periods of time, thus reducing fatigue. In addition, a good-fitting helmet that
resists changing position while being worn is better for mounting onto it other equipment,
such as specialized visors and helmet-mounted displays (HMD/JHMCS).
Another benefit of the HGU-86/P is
its emphasis on preventing hearing damage and pilot's mental fatigue. The HGU-86/P
incorporates an ear-cup tensioning system that allows the helmet's ear-cup to be drawn to
the head, blocking out excessive background noise and increasing the level of
hearing.
This type of noise attenuation represents a reduction in pilot workload by freeing the
brain from burdensome efforts to cancel out unwanted background noise, allowing the pilot
greater ability to concentrate and process information. This improved mobility and
endurance for pilots. With its advanced design, the HGU-86/P helmet reduced the stresses
on a pilot's neck by 20 percent during high-speed ejection compared to current helmets.
The helmet also incorporates a suspension system to prevent high-G turns affecting
Helmet-mounted display optics. Breathing hoses are supplied by Parker Symetrics of Newbury
Park, Calif.
The mask
The HGU-86/P is currently tested with the MBU-22/P oxygen mask. This mask being a further
development of the MBU-20/P.
The future
"From a pilot's perspective, the integrated suit is better because you get used to
wearing the same thing. It's already a stressful time if you have to go into combat, and
it helps if the suit, mask, and helmet are already familiar and you don't need to add
extra things for over water flights and CB," says Boeing chief test pilot Chuck
Killberg. The Air Force has yet to buy the ensemble for production F-22s. The entire
flight gear set-up is currently being tested at Brooks AFB and Edwards AFB. The gear and
helmets must be available by 2004. The Air Force is considering the HGU-86/P for all its
fighter aircraft.
note: Taken from, amongst others, Air Safety Magazine and
altered, more info on this subject can be found in the JHMCS article. |