MICHAEL PHELAN / PARIS
Dutch firm demonstrates material in F-16 flight and is optimistic about JSF prospects
Dutch landing-gear developer SP Aerospace has flown what it says is the first titanium metal-matrix composite (TiMMC) landing gear component. Last week's flight by a Royal Netherlands Air Force Lockheed Martin F-16 fitted with a TiMMC main landing-gear lower drag brace followed tests in 2001 using a similar polymer composite part.
SP also makes the landing gear for the NH Industries NH90 helicopter and, as part of a separate research effort, has built two polymer matrix composite (PMC) demonstrators of the main landing-gear trailing arm.
Tjaard Sijpkes, SP Aerospace technology and development manager, says the PMC and TiMMC materials offer significant weight savings over traditional 300M steel. "The hollow PMC structure is about 1.5cm [0.6in] thick, and is about 5kg [11lb] lighter than the standard 26kg 300M structure," he says.
For the F-16 brace the standard version weighs 7.7kg. SP has managed to achieve a 35% weight saving for the PMC version tested in 2001 and more than 40% for the TiMMC version. "We could get the TiMMC brace down to 4.2kg, but we're conservative for the first flight example," says Sijpkes.
He is optimistic about the long-term use of such material in landing gear. "PMC gear components cost 15% less than 300M components based on a production run of 1,000, so it's a win-win scenario," he says. "Because we use high-pressure resin injection, there's no limit on component size."
Manufacturing is not problematic, but Sijpkes says a real effort is needed to understand the damage tolerance of the materials. Flaw detection and life prediction are important for safe-life components. "For example, we need to figure out how much protective titanium coating is required around the TiMMC structure to protect it from foreign object damage," he says.
TiMMC technology is expensive, however, costing about three times as much as 300M components.
Sijpkes says: "The technology would cost about €4,000 [$4,650] per kg of saved weight, which is not far beyond what fighter aircraft designers are willing to pay, especially far from the aircraft centre of gravity." He says the company is in talks with major landing gear manufacturers about applying SP's expertise, and is hopeful the materials will feature on the Lockheed Martin F-35 Joint Strike Fighter.
Source: Flight International
