The U.S. Marine Corps' short-takeoff/vertical-landing (STOVL) F-35B Joint Strike Fighter (JSF) has completed all of the vertical landings and about 80 percent of the short takeoffs required to begin testing aboard an amphibious assault ship later this year, according to a test pilot at Naval Air Station Patuxent River, Md.
The tests are filling in details about the plane's flight characteristics, which are turning out to be quite similar to the F/A-18 Hornet.
The STOVL variant, which was placed on a two-year "probation" late last year by Defense Secretary Robert Gates, has been plagued by teething problems with various inlet doors and other ancillary hardware associated with vertical landings.
"The testing has been going very well over the last couple of months," said Marine Lt. Col. Matthew Kelly, an F-35 test pilot with an F/A-18 Hornet background. "We have performed all the vertical landings necessary to go out to the boat and do testing. We're at about 80 percent of the short takeoffs."
Over the past three months, pilots at the Maryland base have flown more than 125 sorties, many of which were dedicated to preparing for shipboard testing, Kelly said.
"Right now, we're in very good shape to get all of our testing done and to be ready to go to the ship this fall," he said.
Eventually, the F-35B will perform vertical takeoffs, but that testing has yet to be performed because other STOVL trials are of more immediate import, Kelly said.
"There is a requirement for that and we do plan on performing vertical takeoffs," he said.
Marine Corps leaders, who have steadfastly stood by the F-35B as their primary warplane, said they are optimistic about the variant's future.
"We're very encouraged with the performance of the aircraft in tests this year," said Brig. Gen. Gary Thomas, the Marines' assistant deputy commandant for aviation. "Just through early May, we've done seven times the number of vertical landings that we did all of last year. I think we're at about 200 percent of our planned test points today."
The improving test results will be part of discussions between Marine Corps and Defense Department leaders on how the F-35B will get off the probation list, Thomas said.
But so far, there has been no decision on the criteria that will be used to judge the jet's progress, he said.
A Familiar Flight Envelope
The F-35 program is also making headway in clearing the flight envelope to begin training at Eglin Air Force Base, Fla. There have been few surprises, Kelly said.
Operational pilots should be thrilled with the F-35's performance, Kelly said. The F-35 Energy-Management diagrams, which display an aircraft's energy and maneuvering performance within its airspeed range and for different load factors, are similar to the F/A-18 but the F-35 offers better acceleration at certain points of the flight envelope.
"The E-M diagrams are very similar between the F-35B, F-35C and the F/A-18. There are some subtle differences in maximum turn rates and some slight differences in where corner airspeeds are exactly," Kelly said.
Thomas, who is also an F/A-18 pilot and a graduate of the Navy's Top Gun program and the Marines' Weapons and Tactics Instructor Course, agreed that all three variants should be lethal in the within-visual-range fight.
Beyond visual range, the aircraft's radar and stealthiness will enable it to dominate the skies, Thomas said.
Stealth will allow the F-35 to go into the teeth of enemy air defenses, which are becoming increasingly lethal, Thomas said. The Marines intend to operate the F-35 for 30 to 40 years, when stealth may be required even for close-air support.
"Stealth is going to be a requirement," Thomas said, echoing a point one normally hears mostly from U.S. Air Force officials.
Alongside stealth, the sensors and networking are crucial to the F-35 program.
To that end, Kelly said that mission systems testing for the jet's radar and infrared sensors have been going well. He offered unqualified praise for the F-35's APG-81 active electronically scanned array radar.
The program is testing Block 1 software, which will be used to start training. The standard for Initial Operational Capability (IOC) will be the Block 3 software for the Air Force and the Navy, but the Marine Corps will likely declare IOC with interim software Block 2B flying on F-35B aircraft based at Marine Corps Air Station Yuma, Ariz., Thomas said.
The pace of software development will ultimately dictate when IOC will happen, he said.
The first operational F-35Bs will be delivered in 2012 using Block 2B software, Thomas said.
Defending The Buy
Thomas vigorously defended the service's planned purchase of 340 F-35B aircraft as vital to the Marine Corps' amphibious operations. The "basing flexibility" offered by the aircraft would allow the Marines to operate not only on amphibious assault ships, but also from expeditionary airfields closer to ground combat zones.
Marine air wings have the ability to construct short runways easily, he said. Moreover, there are 10 times as many short runways as 10,000-foot runways.
The service has singled out the F-35 and the Amphibious Combat Vehicle, which replaced the recently canceled Expeditionary Fighting Vehicle effort, as its two most essential programs in the forthcoming budget crunch.
"Within our investment portfolio, we feel those are capabilities we really need, and that's where our priorities are going to be," Thomas said. "There is no Plan B."
However, the Marines are also planning to buy 80 F-35C carrier variant aircraft, which would fill out five squadrons of 10 planes each. Those aircraft would operate as part of the Navy's carrier air wings while the remainder would be used for training, depot maintenance and attrition reserves. The Marines will receive three F-35C models in 2014.
The shift came about because STOVL operations would disrupt the launch cycle onboard the Navy's large deck carriers, Thomas said. "The Navy felt at this time it would be more appropriate to continue with the conventional F-35C," he said.
Flying both variants will not impose enormous strains on the Marines' training and logistical pipelines because the planes are largely similar, Thomas said.
It should be comparatively easy for pilots to move between F-35 variants, Kelly said.
Flight testing for the F-35C carrier variant is also proceeding on course.
"We've made very good progress over the last few months with what we call flutter testing, which is generally the first line of testing of a new airplane," Kelly said.
The C-model aircraft has flown supersonic and has performed the first trial hook-ups for the catapult launchers found onboard U.S. Navy aircraft carriers.
Next week, a second F-35C will arrive at Patuxent River and will be used to expand the G-loading envelope, Kelly said.