EDWARDS AIR FORCE BASE, CALIFORNIA, July 20, 2001. Mission X was to be the graduation exercise for the Lockheed Martin X-35B, the Short Take-Off and Vertical Landing (STOVL) concept demonstration aircraft.
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The STOVL aircraft fulfills only one of three service roles the X-35 Joint Strike Fighter was designed for. The STOVL design will replace the Marines’ AV-8B Harrier. There’s also a conventional-takeoff-and-landing (CTOL) version for the U.S. Air Force, and a beefier version for the Navy’s punishing catapult launches and arrested landings. The call sign of all X-35 test pilots is “Hat Trick,” which is the term for three goals scored by one hockey player in a single game.
The sortie was to consist of a short takeoff, climbing to 25,000 feet, making a supersonic dash, and returning to the field for a vertical landing. Each event, in and of itself, was not a breakthrough achievement and had been accomplished on a previous X-35B sortie, but putting them all together on one flight would be an aviation first. Previous STOVL aircraft achieved supersonic speeds when they had been put in a steep dive, but today we would up the ante by making a level supersonic dash.
The day started with a pre-sunrise flight brief. The early start allowed our team to complete testing before other units at Edwards started flight operations. Additionally, today the field was to close from 10 to 11:30 a.m. for a memorial service. We planned to be done with our test by 9, so there was little time to spare.
Until now, I had flown the aircraft for only three brief vertical takeoffs and landings, which gave me a total flight time of about three minutes. The first flight of the day would basically familiarize me with STOVL flight, allowing me to get a feel for the airplane while completing just a few test points. After landing, the ground crew would hot-refuel the jet (load fuel with the engine running), and I would take off again. The second flight would be Mission X.
With all the buildup we had given Mission X over the past three years, I suppose I should have been more excited. Actually, I was more focused on completing all the test events and, more importantly, not making a mistake. Although Mission X consisted of only the three basic events, there were several other test events planned to fill the rest of the sortie. As I was gathering my flight cards (which include tests to perform, the order in which to execute them, pertinent cautions or limitations, and space to make notes), the lead military flight test engineer shook my hand and said, “Good luck, and don’t forget to have fun out there.” I guess I must have looked more worried than excited. I thanked him and walked to the hangar to get my flight gear. After suiting up and completing my preflight, I gave the airplane my traditional pat on the nose. I wouldn’t say I’m superstitious, but that day I wasn’t taking any chances.
The first flight went very well, and I was able to get a good feel for the airplane while it was in the STOVL mode. Perhaps the most surprising thing about the flight was that there were no surprises. All that time in the simulator had paid off. In fact, the previous night, the simulator team stuck around late so I could practice the mission profile a few times. Another reason the flight had gone well was that the airplane was very easy to fly. Although the Harrier is a remarkable airplane and an amazing achievement in its own right, it is difficult to fly. It takes a long time to train a Harrier pilot, and he must practice a lot to stay proficient. If the first flight in the X-35B was any indication, we were on the right track to making STOVL flight much easier.
During the few minutes it took to refuel, I went over the sequence of events for the Mission X flight. When the test conductor called on the radio to talk about prioritizing the events in the test cards, I realized that we were going to cut it close to the field closing time. There wasn’t any room for mistakes or repeats. The little bit of extra pressure would help keep me on my toes.
I was finally ready to go. Once in position for takeoff I moved the Thrust Vector Lever (TVL) back about an inch, initiating the process of converting the aircraft from CTOL mode to STOVL. Behind the cockpit, four sets of doors were opening. This would allow air to flow through the lift fan and enable the vectoring rear nozzle to move through its full range of travel. While the doors were opening, the clutch was engaging, transferring power from the engine to the lift fan. The only noticeable change in the cockpit was an increase in noise as the lift fan spooled up.
A “good conversion” call came from the control room, which confirmed the indications in the cockpit. I radioed the chase aircraft that I was ready and slowly advanced the throttle and released the brakes. The aircraft quickly accelerated down the runway, and at 80 knots, after only 200 feet, I vectored the thrust to 60 degrees and the aircraft leapt off the ground. I completed the post-takeoff checks, climbed through 5,000 feet, and converted the aircraft from STOVL mode back to CTOL by moving the TVL fully forward.