True Cost Of The Most Advanced US Aircraft Carrier - BusIn > .
Flying military jets is a dangerous business. In the event of an aircraft's experiencing difficulties when coming in to land – whether that's a mechanical failure, like its brakes, or an unforeseen emergency, like hitting a bird – airfields are equipped with safety systems to bring a jet to a halt.
The RHAG is the Rotary Hydraulic Arrester Gear. The blades are immersed in an AL39/ water mix so it does not freeze in winter, the barriers are used by aircraft that don't have tail hooks. Cables can be set for Approach or overrun.
An arresting gear, or arrestor gear, is a mechanical system used to rapidly decelerate an aircraft as it lands. Arresting gear on aircraft carriers is an essential component of naval aviation, and it is most commonly used on CATOBAR and STOBAR aircraft carriers. Similar systems are also found at land-based airfields for expeditionary or emergency use. Typical systems consist of several steel wire ropes laid across the aircraft landing area, designed to be caught by an aircraft's tailhook. During a normal arrestment, the tailhook engages the wire and the aircraft's kinetic energy is transferred to hydraulic damping systems attached below the carrier deck. There are other related systems which use nets to catch aircraft wings or landing gear. These barricade and barrier systems are only used for emergency arrestments for aircraft without operable tailhooks.
Land-based military airfields operating fighter or jet trainer aircraft also use arresting gear systems, although they are not required for all landings. Instead, they are used for landing aircraft on short or temporary runways, or for emergencies involving brake failure, steering problems or other situations in which using the full length of the runway is not possible or safe. There are three basic types of land based systems: permanent, expeditionary, and overrun gear.
Permanent systems are installed on nearly all U.S. military airfields operating fighter or jet trainer aircraft. Expeditionary systems are similar to permanent systems and are used for landing aircraft on short or temporary runways. Expeditionary systems are designed to be installed or uninstalled in only a few hours.
Overrun gear consisting of hook cables and/or elastic nets known as barriers are commonly used as a backup system. Barrier nets catch the wings and fuselage of an aircraft and use an arresting engine or other methods such as anchor chains or bundles of woven textile material to slow the aircraft down. On some land-based airfields where the overrun area is short, a series of concrete blocks referred to as an engineered materials arrestor system is used. These materials are used to catch the landing gear of an aircraft and slow it via rolling resistance and friction. Aircraft are stopped by the transfer of energy required to crush the blocks.
The first use of a barrier on a military airfield was during the Korean War when jet fighters had to operate from shorter airfields where there was no margin for error. The system used was just a transplant of the Davis Barrier used on straight deck carriers to keep any aircraft that missed the arrest wires from crashing into the aircraft parked forward of the landing area. But instead of the more complex hydraulic system used on carriers to stop the aircraft when it hits the barrier the land based system used heavy ship anchor chains to bring the aircraft to a halt.
Permanent systems are installed on nearly all U.S. military airfields operating fighter or jet trainer aircraft. Expeditionary systems are similar to permanent systems and are used for landing aircraft on short or temporary runways. Expeditionary systems are designed to be installed or uninstalled in only a few hours.
Overrun gear consisting of hook cables and/or elastic nets known as barriers are commonly used as a backup system. Barrier nets catch the wings and fuselage of an aircraft and use an arresting engine or other methods such as anchor chains or bundles of woven textile material to slow the aircraft down. On some land-based airfields where the overrun area is short, a series of concrete blocks referred to as an engineered materials arrestor system is used. These materials are used to catch the landing gear of an aircraft and slow it via rolling resistance and friction. Aircraft are stopped by the transfer of energy required to crush the blocks.
The first use of a barrier on a military airfield was during the Korean War when jet fighters had to operate from shorter airfields where there was no margin for error. The system used was just a transplant of the Davis Barrier used on straight deck carriers to keep any aircraft that missed the arrest wires from crashing into the aircraft parked forward of the landing area. But instead of the more complex hydraulic system used on carriers to stop the aircraft when it hits the barrier the land based system used heavy ship anchor chains to bring the aircraft to a halt.
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