The Lockheed Martin F-35C carrier-based version of the Joint Strike Fighter is making steady progress towards sea-trials onboard USS Nimitz (CVN-68) in October according to a company official.
“We are working very hard to get the airplane ready for sea trials, DT-1 sea trials, starting in mid-October,” Eric Van Camp, Lockheed’s domestic F-35 business development director, told USNI News on May 30. “The at-sea period I believe extends from roughly the 12th of October to the third of November.”
However, there are still many tasks that the F-35 integrated test force must complete before the C-model jet can make its first carrier launches and arrested recoveries onboard Nimitz.
One of the biggest remaining hurdles is a structural survey of the jet’s landing gear and airframe. “When we say structural survey it sounds like what we’re doing is parking it some place and doing some inspections, but actually what we are doing is we doing a specific set of flight test points that are designed to understand how the airplane reacts both aerodynamically and structurally when we put it in off-nominal conditions,” Van Camp said.
Those off-nominal conditions could include very high excessive sink rates, different aircraft attitudes in all axes or a combination thereof when the jet touches down on the carrier flight deck. The Navy has to test any carrier-based aircraft in those kinds of conditions because of the harsh environment at sea—which could include a pitching flight deck due to weather or other factors including human-induced errors.
“We’re trying to emulate the range of conditions that an airplane might be forced to recover onboard the ship,” Van Camp said.
Those tests are currently underway at Naval Air Station Patuxent River in southern Maryland with shore-based catapults and arresting gear, but Van Camp notes that its not the same as landing on a real carrier. F-35C test pilots will have to check-off 44 separate test points to ensure the JSF is safe to trap onboard a carrier using a specifically instrumented test airframe.
Recently, on May 29, the F-35C demonstrated its ability to land safely at its maximum allowable sink-rate of 21.4 feet per second, Van Camp said. Once the testing is complete, the aircraft would be cleared to make unmonitored carrier landings. “We’ll be pretty close to the point where we’re confident that when we take it to the ship it will be cleared for unmonitored loads,” Van Camp said. “In other words an uninstrumented aircraft.”
The point of DT-1, Van Camp said, is to create an aircraft launch and recovery bulletin for the fleet operators who will fly the jet during routine air wing operations.
Assuming DT-1 concludes successfully, the F-35 program will move on to a second much more challenging detachment onboard a carrier at a later date. The testing will likely mirror the process seen with the F-35B short take-off vertical landing jet’s sea-trials onboard USS Wasp (LHD-1), Van Camp said.
“You progressively expand the envelope within which the aircraft can launch and recover,” he said.
In addition to the carrier launch and recovery portion of the flight-testing, the integrated test team continues to expand the F-35C’s up-and-away envelope. Testing continues for high angles-of-attack, high-speed flutter, loads and other aspects of the flight envelope.
“All of that continues in parallel with the work that we’re doing at the ship,” Van Camp said.
By the time the F-35C is cleared to receive the interim Block 2B software, the aircraft will be cleared to 40,000, 550 knots calibrated airspeed, Mach 1.2, 50 degrees angle-of-attack and 7.5G. It will also be cleared to carry a basic suite of weapons including the Raytheon AIM-120 air-to-air missiles, Joint Direct Attack Munitions and laser-guided bombs.
The Navy expects to declare the F-35C operational in August 2018 with the full Block 3F software suite. That means a full suite of weapons, data-links and sensor integration and a full flight envelope. For the F-35C, that equates to 50,000 ft, 700 knots, Mach 1.6, 50 degrees angle-of-attack and 7.5G.