Wednesday, August 26, 2009

South Korea toys with four options to build indigenous attack helicopter

An attack derivative of the Surion utility helicopter is shaping up as a likely project to sustain Korea Aerospace Industries’ hard-won aeronautics development skills. As the engineering effort on the Surion winds down, other projects that could keep the company’s engineers busy include a civil aircraft, such as the regional jet revealed last year, and the KFX fighter.

The need for development work is clearly driving the push for a home-grown attack helicopter, since foreign producers already offer advanced models whose price and performance could be difficult for Korea Aerospace, a new arrival in the rotary-wing business, to improve on. The South Korean government and industry are considering four alternative schemes under the Korean Attack Helicopter program to fill the requirement for 274 aircraft to replace about 70 Bell AH-1Ss and 270 Hughes 500s from 2018:

•A simple addition of stub wings and weapons to the Surion. With 87% commonality with the Surion, development of this model would take four years and cost 200 billion won ($160 million), Korea Aerospace says. The unit price would be 21 billion won. •A new stepped cockpit grafted on to the Surion cabin, along with the wings and weapon systems, with 73% commonality. Development time and cost would rise to five years and 700 billion won, and unit cost to 23.1 billion won.

•A new body, including cockpit, but otherwise retaining as much as possible from the Surion, notably the power train, and offering 63% commonality. This aircraft would need six years and up to 1 trillion won for development and would cost 24.8 billion won per unit.

•An attack helicopter unrelated to the Surion. This could be an adaptation of a foreign design.

None of these concepts will be free from criticism.

The first two seem to be highly compromised in the quest for commonality, since the engines would have to haul around the mass of a transport helicopter body that would offer little advantage in an attack mission while offering a larger, more sluggish target.

The second option is visually similar to the 12-ton Mil Mi-24 assault and attack helicopter, but the South Korean aircraft would not act in such a role, striking from the air and landing infantry to assault from the ground. A scale model shows that the design has no large doors for infantry, and that the cabin could be obstructed by carry-through structure of the mid-mounted wings.

All three proposed derivatives may be open to the charge they are bigger than necessary, a result of the choice of the power train from the 8.7-metric-ton Surion.

The Korean Attack Helicopter program has been aimed at developing a light- to medium-size aircraft, akin to the 6-ton Eurocopter Tiger. South Korea’s AH-1s have a 4.5-ton maximum weight.

But the rating of the Surion’s two General Electric T700-GE-701K turboshafts—each at 1,383 kw. (1,854 hp.) for 10 min.—would put an attack derivative in the same class as the Boeing AH-64 Apache, which has a design mission gross weight of 8 tons and an overload ferry-mission weight of 10.4 tons.

The South Korean armed forces have sought Apaches, but only 36. That effort may be dropped in favor of the Korean Attack Helicopter.

If the proposal for an aircraft unrelated to the Surion produced an all-new design, it would face criticism as a costly reinvention of what was already available. A new helicopter would, however, offer to greatly extend the rotary-wing skills that Korea Aerospace has learned from developing Surion with help from Eurocopter.

Any of the three derivative designs would add to the considerable production run of components for the 245 Surions that the armed forces and government have said are required. A derivative attack helicopter would result in South Korea building 519 related helicopters.

Foreign support for attack helicopter development would also be likely, with Eurocopter well placed for the work.

The Surion has been developed under the Korean Utility Helicopter program, the survivor of the former Korean Multirole Helicopter program, which also encompassed an attack helicopter until that element was dropped in January 2005 to reduce development risks.

The attack derivatives of the Surion therefore revive the original proposal for two helicopter types under a single broad program.

One military official tells the Yonhap news agency that development must begin next year for entry into service by 2018. The national security council directed in 2005 that no decision on the attack helicopter be taken before an assessment of the Surion, now due by October 2010. The finance ministry is accordingly refusing to release the first 3 billion won of development funding for the attack helicopter until then.


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