Tuesday, July 17, 2012

Military Airplanes

The militaries of the United States and its allies are in need of a new fighter aircraft. Although the American F-22 is considered the most advanced fighter aircraft in the sky today, it is expensive to build and maintain and slow to deploy. The Joint Strike Fighter program was begun to develop an affordable, lethal aircraft that could fight anywhere in the world in any weather with less than one day's notice.


Five years ago, Lockheed Martin and Boeing began developing competing protoypes for the JSF program. In October, Lockheed Martin's was selected for future development.

The X35 (to be designated the F-35 once it reaches regular production) incorporates a number of unique design innovations that set it aside from everything else in the sky today.

STOVL

The US and British militaries specified that the JSF must have available models with "short take-off vertical landing" (STOVL) capabilities. The Royal Air Force and US Marines require carrier-based fighters that can launch from short runways and land on flight decks and landing strips not much larger than the planes themselves.

Currently, this need is filled by the British Harrier. Harriers direct their jet engines though nozzels that can be angled downward, allowing them to launch and land vertically or hover in mid-air. The Harrier is limited, however, both in speed and payload: it is roughly half the size of the X35, and unlike most modern fighters it flies only at subsonic speeds.

The STOVL X35 uses the engine's turbine shaft to power two counter-rotating fans located behind the cockpit, producing nearly 20,000 lbs. of lift. This reduces noise, wind, and heat, while doubling the force available from a Harrier-type design.

An X35 was the first STOVL aircraft ever to fly supersonic and land vertically in the same flight.

Construction

The F-35 will have half as many parts and mechanical fasteners as an F-16, with each component manufactured and placed by laser-guided machinery. Assembly steps that could take days, or even weeks, on older fighters can be accomplished in minutes.

More reliable components and a greatly reduced internal support structure mean that the F-35 will require less maintenance and will allow easier access to workers.

Three variants of the prototype have been produced: the X35A (standard configuration for the US Air Force), the X35B (STOVL), and X35C (for the US Navy, with wider wings and a heavier support structure for carrier landings and takeoffs). The production processes and tooling have been designed so that the same equipment can be used to manufacture any of the three variants.

Once full production on the plane begins, it is expected to cost $30 million per unit--$70 million less than an F-22.

Stealth

The United States military and its contractors have spent billions developing technology to render aircraft practically invisible. Smooth, aerodynamic shapes reduce the reflection of radar waves and, along with the planes' coloration, make it difficult for other aircraft to visually detect them. Engines are shielded within the bodies of the aircraft and vents are shaped to spread their exhaust, eliminating their infrared signature. Advanced materials used in stealth aircraft absorb radar waves and prevent electromagnetic detection.

All of these features enhance the "survivability" of an aircraft (that's the military's way of saying that it is less likely to be shot down), but are costly. The extreme case is the B-2 Stealth Bomber. This is a long-range heavy bomber (it can carry twenty tons of bombs six thousand miles without being refueled and flies from three bases to virtually anywhere in the world with a single in-air refueling) with a radar cross-section (the solid area apparent to radar detection) roughly the size of a large bird. B-2 bombers cost more than $2 billion each, with F-22's running at $100 million.

For the Joint Strike Fighter program, focus has shifted from providing the most perfect stealth possible to using stealth technology in an affordable design, finding a balance between survivability and cost.

In flight, the X35 creates roughly the same radar reflection as a piece of metal the size of a golfball. This means that it is easier to detect than the F-22 (which have less radar visibility than a marble), but should be able to evade detection by any potential enemy.

The JSF will be produced with fewer expensive radar-invisible composites than the F-22, but designers have reduced the total number of surfaces, seams, steps, and external imperfections to reflect radar. Long-lastings surface coatings and more precise manufacturing techniques will make this the first stealth aircraft that can be deployed without climate-controlled hangars and special putties and paints for minor surface repairs.

The Future

Lockheed's protoypes have now been allowed to progress to the "System Design and Development" phase with a $19 billion contract to further develop the design over the next ten years. If all goes well, Lockheed will have an opportunity at a much larger contract: $200 billion to deliver three thousand F-35's to the British and United States governments.