<i>Does the USAF really want this F-35B, or are they looking for a devious way to kill it? If I was a project killer, this would be the way to do it. This is the strongest indication yet of the end of the STOVL. There has got to be panic in the F-35 System Program Office.</i>
<b>USAF comments trigger debate on short-takeoff-and-landing F-35B</b> (Posted: Monday, September 27, 2004)
[Sept. 27, 2004, Aviation Week & Space Technology]
Forget Vertical
USAF comments trigger debate on short-takeoff-and-landing F-35B
By David A. Fulghum and Robert Wall, Washington
There has been a collective holding of breath as Pentagon officials await reaction to a U.S. Air Force announcement that it wants to buy hundreds of short-takeoff F-35B joint strike fighters modified to provide close air support for Army and Marine Corps ground forces.
A major unanswered question is whether the USAF version would simply have a different paint job, helping decrease the price of F-35Bs for the Marine Corps because of added production, or would become a fourth variant of the aircraft with specialized equipment and optional design components that might clear the way for more flexibility for foreign customers.
At the same time, weapons designers are still coming to grips with the decision to shrink the weapons bay on the standard short-takeoff-and-vertical landing (Stovl) F-35B. Some munitions have already been eliminated, but industry officials worry that the loss of available space could cause interference among the different weapons. For example, an industry official noted that design changes to such a confined space could cause weapons fins to strike one another.
MOREOVER, European officials are trying to assess the impact of the Stovl configuration change on their efforts. In particular, missile designers are trying to gauge how to build their future beyond-visual-range air-to-air missile (Meteor) to fit into the more confined space. Folding wings are one option being looked at, but the U.S. has been slow to share information on the new bay shape, complicating the weapon studies.
Researchers also are working on enhancements to the fighter's stealth performance. Of particular note, special materials-maker Esterline Technologies is teaming with Lockheed Martin's Skunk Works to combine the properties of its stealth coatings with materials that have the ability to withstand increased temperatures generated by high performance aircraft, says Robert Cremin, chairman and CEO of Esterline. Current stealth coatings can degrade when surface heating occurs. The new material, which Cremin believes will be ready in time for JSF, should eliminate that problem.
For a specialized Air Force version of the F-35B, yet other changes are emerging. So far mentioned by various Air Force and aerospace industry officials as possible changes to the design are: an internal 25mm. cannon (not the Marine Corps' gun in a pod), a refueling probe instead of a boom receptacle, a larger wing for greater fuel carriage and lift, as well as a modified propulsion scheme that accentuates short takeoff and landing, but avoids vertical landing. The last could allow additional thrust to be diverted into the core engine and away from the roll posts needed for stability during hovering flight.
Advocates are excited about possibilities that the new design offers to exercise the JSF design's modularity. But critics worry that such excursions will dilute the emphasis on savings and commonality.
<u>"The Air Force wants a Stovl F-35B, there's no doubt about that," says a senior aerospace industry official. "They wanted to replace all of the A-10s with them, but the Air National Guard objected. Because the ANG insisted on keeping them, the Air Force will now operate a mixed force." But they still need to replace three wings of A-10s which would require a total of about 300 JSFs to keep the logistics and training pipeline functional.</u>
The declaration also could signal an early move in the Air Force's strategy to cope with predictions of a decade of shrinking budgets and dramatic reductions in force structure.
"Next year is going to be a crunch year [for the Fiscal 2006 military budget plan]," says U.S. Sen. Joseph Lieberman (D-Conn.). "The fighter programs are going to be under intense scrutiny. I wouldn't be surprised to see a reduction in the overall buy [of] both the JSF and F-22. We are going to rob from acquisition funds to support current operations."
"The surprise is that the Air Force wants to tailor the F-35B Stovl for [itself] instead of just changing the name on the side from Marine Corps to Air Force and maximizing commonality," the industry official said. "They can't do both receptacle [boom] refueling and probe and drogue, so they will take the Marine Corps probe. But they want an internal gun. That takes up a lot of space and it will change the mold line because they will have to work around the [vertical] lift engine.
"There's also a new idea that if you can eliminate vertical landing as a requirement [while keeping short takeoff] the payload could go up," he said. Part of Lockheed Martin's weight reduction program is already planned to re-route some thrust from the wing-mounted roll posts through the core engine to increase power.
Engine makers are officially mum while awaiting word from the Air Force with some specifics about what they might want. However, informally some senior officials are at least thinking about how or whether they should add the roll post vents to the larger Navy wing to give the design extra stability during short takeoffs and landings.
Aerospace industry analysts say several factors could make a propulsion system specialized for the Air Force interesting and necessary. The Air Force wants more range on its short-takeoff version of the aircraft, so it would need to look for strategies to increase the fuel load, while decreasing consumption.
Not conducting vertical landings, for example, would help loosen performance requirements and limit the flight envelope to more fuel-efficient maneuvers. Moreover, adding the larger wing from the Navy's carrier-based F-35C would also allow the carriage of more fuel and thereby increase range or payload. Aerospace propulsion specialists say European customers have also expressed interest in the larger Navy wing. In the long term, the increased 40,000-lb.-thrust, alternative General Electric F136 JSF engine could also help an Air Force F-35 short-takeoff variant compensate for the weight of additional fuel and weapons. It is to begin testing in 2005.
"But the Marine Corps says that if the configuration changes, the price will go up. That breaks faith with affordability and commonality and could end up by not benefiting the Marine Corps at all," said the industry official.
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