<XMP><BODY></xmp> Safety Improvements to Airliners.





Safety Improvements to Airliners.

        This page contains some of my own suggestions to improve airliner safety or ideas from other people that I like. Some of the things I've been reading on the topic baffle me. How can an airliner crash just after take off because of iced up control surfaces? Isn't it part of the pre-flight checks to ensure that all moving parts are doing just that -moving?

        One of the primary areas for improvement on airliners that I can see is to remove the engines from the underside of the wing.
        Firstly, it seems to me that by being closer to the ground these are more likely to pick up debris during take off.
        Removing the engines from this position will also give a smooth ventral surface –more suited to making crash landings when the landing gear will not deploy. If an aircraft is landing on the ocean the engine pods will act as unwelcome braking devices. This is particularly a problem if one engine touches the water before another. When crash-landing on a runway the engines will be grated against the tarmac, throwing up sparks and greatly increasing the chances of fuel fires.
        There is no reason that I'm aware of that engine pods cannot be on top of the wing. Some prototype Russian and US military transport jets have had the engines placed just ahead of and above the leading edge of the wing –a configuration intended to create more lift and decrease take off and landing distances. There have been plenty of designs of airliner that have mounted the engines back at the tail, so there is no reason why this could not be done for a future 747 sized craft.
        Another engine improvement would be the insulation of grills to reduce the chances of the engines taking in birds or debris. Certain high performance Russian military fighters have this feature already so no reason why an airliner shouldn't.

Parafoils
        This site:-

http://www.dropzonepress.com/faq-01.htm

addresses the idea of fitting large airliners such as 747s with parafoils that can be deployed in the event of engine failure or structural damage. When I first heard of these I though they would be quite heavy, and toyed with the idea that the canopies might also help insulate the upper part of the cabin. In fact each parafoil and associated gear weighs only 45lbs. Five parafoils can save a 747 for a total weight less than that of a single American tourist. Five parafoils cost $30,000 and saves $150 million of jet, not to mention the saving in human lives – figures that even the meanest bean-counter won't fail to be impressed by. Obviously foils would need to be fireproof.

The Hackenbacker Device
        This idea was shown on the classic TV show Thunderbirds (episode 29, in fact)
        Put very simply, the Hackenbacker device is an ejectable fuel tank that can be flown to several thousand feet above the aircraft and safely exploded –letting the airliner crash-land without several tons of highly inflammable liquid on board.
        The Hackenbacker in the TV show was a sort of external pod/rocket plane. There is no reason why this could not be within the airframe and designed to make a purely vertical flight, like a ICBM leaving a Submarine. The Hackenbacker tank would initially be launched by solid fuel rockets, then sustain its flight up to a safe detonation altitude using the liquid fuel in the tank. Not much fuel in the tank? - then the tank doesn't need to fly as far.
        Detonation system for the tank would have at least triple redundancy.
        I'd build the Hackenbacker tank into the rear of the airframe. The joke that "I've never heard of an airliner backing into a mountain" has some merit!
        The Hackenbacker tank may not be large enough to carry all of an airliner's fuel, and in this eventuality it would be standard practice to use up the fuel in wing tanks first. By moving the sewage storage tanks to the wings more room for fuel might be freed in the body.
        In the event of parafoil deployment the Hackenbacker would usually be jettisoned before the foils are released. If the plane is flying with foils it doesn't need the fuel or its weight.
        An added bonus of the Hackenbacker is that an airliner can be refueled simply be removing one Hackenbacker tank and inserting another.
        Other fuel ideas :–a moving wall on the fuel tank would prevent the formation of potentially explosive fuel vapor/air mixtures. This may be more weight efficient than the often suggested idea of pumping nitrogen into the emptying tank.

        Is there any real reason why airliners don't have in-flight refueling capability?

        Fuselage construction techniques need to be re-examined. The aircraft body could incorporate continuous structural beams at bottom of fuselage that form sort of "sled"
        Using tracks for landing gear means no blowouts. These would be band tracks, not the heavy metal linked tracks seen on vehicles such as the Abrams tank. The bands would be built up from layers of different colours so excessive wear is really obvious. The tracks would be positioned rather like the wheels of a C-130 and the nose wheel of the aircraft would just be used for steering rather than being load bearing.

        Current trends in airliner design is to increase the body size to increase capacity. This comes with a drag penalty so the wings are made smaller to compensate. This comes with the drawback of less lift so higher take off speeds are needed.
        By redesigning the airliner as a lifting body it would be possible to have both less drag and slower take off and landing speeds. A good example of a lifting body is a shark. Sharks need to keep swimming nearly all the time. If they don't, they drown. They also have no swim bladder or other floatation devices, so a static shark is a sinking shark. Needless to say, the shark shape has to be a very efficient configuration

        Mike Sparks: has pointed out that it would be relatively simple to configure the shape of the airliner so that it could make emergency landings on water if necessary. The three seaplanes linked to below closely resemble airliners in shape. Note that the Be-200 and P6M mounts jet engines above the wing.

Corvair Tradewind
Be-200
P6M Seamaster

Inside the Aircraft.

        Cockpit and flight crew quarters should be given extra shielding against cosmic rays. Since crews fly more often than passengers their health is more at risk from this factor.

        Each passenger position should have a floor well or underseat locker –a box on which seat ahead is built. This is a much safer way to store hand luggage than overhead lockers, and increases structural integrity of seats. It will also stop inconsiderate passengers trying to pass off 70 litre sports bags as hand luggage. If it won't fit in the well it goes in the hold. Seats should also have a rack or similar to secure walking sticks etc.

        Rather than just escape doors, consideration should be given to blow out panels or clamshell doors for rapid evacuation. These would also allow the rapid venting of toxic fumes from burning plastics. Obviously clamshells would not be used during an ocean ditching.

        The crew and passenger area of an airliner could also be constructed as a floating safety cell/pod.

        The oxygen masks in an airliner should incorporate a smoke hood. A valve allows the hood to pull free when the passenger leaves his seat to exit the aircraft. The same system shuts off the oxygen to prevent it feeding fires.
         This system makes smoke hoods available to passengers in an emergency but stops them being stolen for Club 18-30 fancy dress parties. It would be standard procedure to don hoods in the event of an emergency landing. The Oxygen would also sober up passengers and make them more alert.

The MANPADS Threat.
        Missile attacks on commercial airliners are by no means a new phenomenon, dating back to at least 1965. The SA-7 attacks on Rhodesian aircraft in 1978-9 are possibly some of the most well known incidences. It is only recently (possibly since 9-11) that there has been interest in the widespread fitting of countermeasure systems to airliners. The main concern is about “Heat Seeking” Infra-Red (IR) guided shoulder launched missiles, generically known as “MANPADS” (Man Portable Air Defense Systems).

        Manufactures of such countermeasure systems are proposing their latest, most expensive equipment such as DIRCM, a system that detects launched missiles and attempts to blind them with an infra red laser beam.
        In his on-line book Carlton Meyer suggests that such a system operating over a city would be subject to numerous false alarms from sunlight reflecting off windshields or a refinery flaring. It is also not unlikely that many immature individuals with too much free time will devote their energies to finding ways to fool the sensor and trigger their own fireworks displays.

Homeland Defense Journal on DIRCM

        While it is questionable if DIRCM is practical there are simpler countermeasure systems that have been ignored. In military use since the 1970's on over 5,000 aircraft are systems like the AN/ALQ-144 system. This resembles a rotating beacon light that emits infra-red. Missiles lock onto this source and veer to one side as they try to follow the signal, then break lock as the IR source rotates out of view. The principle is rather like a bullfighter's cape and apparently works well against many of the IR guided missiles still likely to be encountered. The AN/ALQ-144 unit weighs only 14 kg. A similar device, the AN/ALQ-140 is built into the tail of the F4 Phantom. The AN/ALQ-157 is designed to protect the large sides of helicopters such as the CH-46 and CH-53.

AN/ALQ-144 Brochure

        Bae are offering the AN/ALQ-204 Matador system for commercial airliners but it is not clear if this is a AN/ALQ-144 type system or DIRCM.
         It is likely that future and some current MANPAD systems can be programmed to ignore AN/ALQ-144 but it is stated to be effective against SA-16 or earlier systems such as SA-16, SA-18, SA-14, HN-5, SA-7, all of which are probably the most likely armament of current terrorists.

MANPAD threats to Commercial Aircraft

        There are other simple measures that can be adopted. During the Yom Kippur War (1973) Israeli A-4 Skyhawks considerably reduced their vulnerability to SA-7 attack by the simple expedient of fitting a tailpipe extension that cause the missile to explode at some distance from the engine. If this works for a small aircraft such as the Skyhawk it should also be effective for a 747 Jumbo. While modern MANPADS don't need to be aimed at the exhaust and will home in on hot metal the tailpipe shot will still remain a likely means of attack.

MANPADS Guidance

        It is worth remembering that IR MANPADS are not the only means by which airliners can be attacked. Several modern MANPADS systems such as Starstreak and RBS-70 use laser beam riding guidance. The British Javelin system used a SACLOS (Semi-Automatic Command to Line Of Sight) system such as is more commonly used on Anti-tank weapons. The operator kept his crosshairs on the target and course corrections were radioed to the missile. The earlier Blowpipe SAM which made several successful kills against Argentine warplanes was steered by a thumb stick. While Javelin and Blowpipe are unlikely to be still encountered such guidance systems may be encountered on homemade missiles or ATGWs fired at airliners. At low altitude just after landing or take-off gunfire and RPGs may also be used. Mortar fire and bombardment rockets may also be used against parked or taxing aircraft.

The typical vulnerability zone around an airport is 80 kilometres long and eight kilometres wide, an area of 640 square km, extending up to an altitide of 4500 metres. The issue of MANPADS protection has no single simple answer but systems such AN/ALQ-144 and tail-pipe extensions may make a considerable difference.
Ref
www.aircrash.org/burnelli/index.htm

        Many thanks to Mike Sparks of the Airborne Equipment Shop for drawing my attention to the topic and the idea of tracked airliners.

An article by Mike concerning Airliners and Transport aircraft.

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