Elec­tro­mag­netic air­craft launch sys­tem

SP's MAI - - FRONT PAGE - [ By Lt Gen­eral (Retd) Naresh Chand ]

The first trial take-off of an air­craft took place from the deck of a US Navy cruiser USS Birm­ing­ham in 1910 and the first trial land­ing took place in 1911. The first plane to take-off from a ship un­der way was from the deck of Royal Navy’s HMS Hiber­nia in 1912. The Ja­panese were mean­while try­ing an­other ap­proach by car­ry­ing sea planes on Sea­plane ten­der sup­port ships dur­ing World War I. Dur­ing Septem­ber 1914, the Im­pe­rial Ja­panese Navy Ship Wakamiya con­ducted the world’s first naval-launched air raid against the Ger­mans. Wakamiya car­ried four Mau­rice Far­man sea­planes, which took–off and landed on the water and were low­ered from and raised to the deck by crane. The devel­op­ment of flat top ves­sels pro­duced the first large fleet ships. In 1918, Royal Navy’s HMS Ar­gus be­came the world’s first ship ca­pa­ble of launch­ing and land­ing naval air­craft.

Since then the tech­nique for the take-off and land­ing air­craft from an air­craft car­rier has be­come more re­fined and safe. The com­mon sys­tems in vogue are: • CAt­A­puLt-As­sIstED tAKE-oFF But Ar­rEstED-rE­Cov­Ery (CA­toBAr). Ca­tobar sys­tem is used for heav­ier air­craft car­ry­ing ex­ten­sive pay­load. US, France and Brazil use this sys­tem. The cat­a­pult is a de­vice used for launch­ing an air­craft from air­craft car­ri­ers and fol­lows the same prin­ci­pal of a cat­a­pult with which one played in younger days to drop fruit from trees or shoot birds. It has a pis­ton which is called a shut­tle and is pro­pelled down a long cylin­der un­der steam pres­sure. The air­craft is at­tached to the shut­tle us­ing a tow bar or launch bar mounted to the nose land­ing gear and is lit­er­ally thrown up­wards from the deck with a ve­loc­ity higher than the min­i­mum take-off. • SHort tAKE-oFF But Ar­rEstED-rE­Cov­Ery (StoBAr). StoBAr sys­tEm Is used with lighter air­craft car­ry­ing lim­ited pay­load like Sukhoi Su-33 and MiG-29K which are nor­mally em­ployed for air su­pe­ri­or­ity and fleet de­fence. This con­fig­u­ra­tion has bow ski-jump and three ar­restor wires on the stern of the an­gled deck. In­dia’s INS Vikra­ma­ditya, which is cur­rently un­der­go­ing a ma­jor re­fit in Rus­sia, is of this type. • SHort tAKE-oFF vEr­tI­CAL-LAnD­InG (STOVL). STOVL sys­tEm CAn be used by Har­rier Jump Jet fam­ily and Yakovlev Yak-38 which gen­er­ally have very lim­ited pay­loads, lower per­for­mance, and high fuel con­sump­tion, how­ever a new gen­er­a­tion of STOVL air­craft, cur­rently con­sist­ing of the F-35B has much im­proved per­for­mance.

Elec­tro­mag­netic Air­craft Launch Sys­tem

Elec­tro­mag­netic Air­craft Launch Sys­tem (EMALS) is un­der devel­op­ment by the US Navy to launch car­rier-based air­craft from cat­a­pults us­ing a lin­ear mo­tor drive in­stead of con­ven­tional steam pis­ton. EMALS con­sists of six sub­sys­tems work­ing to­gether and shar­ing com­po­nents to power the four cat­a­pults on the ship. EMALS is be­ing devel­oped by Gen­eral Atomics for Ford class car­ri­ers. The land-based pro­to­type passed ini­tial tests dur­ing 2010. The EMALS uses a lin­ear in­duc­tion mo­tor (LIM), which uses elec­tric cur­rents to gen­er­ate mag­netic fields that pro­pel a car­riage down a track to launch the air­craft. A 91-me­tre LIM will ac­cel­er­ate a 45,000 kg air­craft to 240 kmph. The elec­tric en­ergy re­quired by a LIM mo­tor in a few sec­onds of its op­er­a­tions is much more than the power the mother ship can pro­vide thus is achieved by a unique sys­tem of stor­ing the power sup­ply in its four disk al­ter­na­tors. It can also be recharged within 45 sec­onds of the launch as com­pared to the cat­a­pult which is much slower.

EMALS is de­signed to en­large the op­er­a­tional ca­pa­bil­ity of the US Navy’s fu­ture car­ri­ers to in­clude all cur­rent and fu­ture car­rier based light­weight un­manned to heavy strike fight­ers.

It pro­vides higher launch en­ergy ca­pac­ity, eas­ier sys­tem main­te­nance, im­proved re­li­a­bil­ity and ef­fi­ciency, and bet­ter end-speed con­trol. EMAL pro­vides smoother ac­cel­er­a­tion at both high and low speeds which re­duces the stress both on the air­craft and the ship. It also re­duces the re­quire­ment of water. The Air­craft Launch and Re­cov­ery Equip­ment Pro­gram Of­fice of the US Navy has re­cently re­ported that EMALS has com­pleted shared gen­er­a­tor test­ing. Fur­ther devel­op­ment and test­ing will con­tinue so that EMAL can be fit­ted on Ford class car­ri­ers. Will the In­dian Navy in­clude EMALS in its In­dian air­craft car­rier pro­gramme?

An E-2D Ad­vanced Hawk­eye launches suc­cess­fully us­ing EMALS

F-35C Light­ning II test air­craft launches

for the first time from the new elec­tro­mag­netic air­craft launch sys­tem

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