Pilots and engineers from Air Test and Evaluation Squadron (HX) 21 based at Naval Air Station Patuxent River successfully tested a more stable method of flying MV-22 Ospreys to and from ships during a weeklong detachment in the Atlantic in late May-early June.
A team of 50 HX-21 personnel embarked on the amphibious assault ship USS Wasp (LHD 1) on May 26 to conduct a series of test flights that would demonstrate the efficacy of a flight control response called attitude mode. In attitude mode, the pilot uses lateral stick motion to control the attitude, rather than the rate, of the aircraft’s roll. This reduces the pilot’s workload when hovering, keeping station, or conducting a landing approach in darkness or brownout conditions.
Maj. Aaron Okun, head of the squadron’s MV-22 flight test department, said that attitude mode was recently certified for use in land-based operations, but has not yet been approved for shipboard landings and takeoffs.
“Landing on a ship is one of the most difficult tasks we perform,” said Okun, the squadron’s 2019 Test Pilot of the Year. “It requires a lot of stability. We believe that attitude mode is a safer and more stable way to fly the aircraft, but until we could demonstrate that it was truly safe for use on a ship, we weren’t willing to let the fleet operators risk flying with it.”
In addition to establishing the flight envelope for attitude mode in shipboard operations, the detachment had an ambitious list of other items it wanted to test during its week at sea, including increasing the aircraft’s takeoff and landing weight, airflow characteristics during landing, ship approach techniques, and hovering performance in a variety of wind conditions. However, as often happens, the detachment’s meticulous plans needed to remain flexible based on factors outside of their control — in this case, Mother Nature.
“The day we got out there, and for the following three days, the weather was terrible,” Okun recalled. “We were in a low pressure system in which you could see blue sky above you, but below 300 feet it was fog everywhere. We could not get more than a quarter of a mile visibility. The day we arrived, we had to wait about an hour and a half to just get enough visibility to make one landing.”
Once the weather finally broke, the ship set course for suitable test conditions and full-on test flying began on Sunday — with just four days of flying time left.
“We were able to knock out a bunch of testing, but we were getting into crunch time and we had to find very specific winds at the edge of the envelope to complete the testing of the attitude mode,” Okun said. “ The ship was fantastic, allowing our test team to dictate where we went. We would ask the METOC [meteorology and oceanography] officer for winds 10 to 15 knots sometime tomorrow between noon and 1600, and he would say, ‘If you want that, this is where we go.’ And off we’d go to that spot, while the ship’s OPSO [operations officer] would reserve the airspace. And when we’d get there, sure enough the weather would be exactly as predicted.”
The team worked up to the last minute wringing data from MV-22 test flights until the ship had to turn for its home port to disembark the detachment. “Around halfway through that last night, we saw we were going to get what we needed and you could feel the atmosphere change,” Okun recalled. “Everybody was beginning to loosen up a little bit as we realized that despite all of the difficulties, we were absolutely going to get the data we came for.”
To help expedite the clearance process for using attitude mode at sea, a NAVAIR engineer involved in the review process accompanied the detachment so that he could see the data in real-time, and the team began drafting its analysis and report almost as soon as it came ashore. Okun expects a final decision within the next three months.
Nicknamed the “Blackjacks,” HX-21 provides developmental flight test and evaluation of rotary-wing and tilt-rotor aircraft and their associated airborne systems in support of U.S. Navy and Marine Corps training, combat, and combat support missions. The squadron can trace its roots at NAS Patuxent River back to 1949, when the then-Naval Air Test Center first established a rotary-wing test division. Today, HX-21 teams are engaged in testing six families of aircraft, including the CH-53K King Stallion, the MV-22 and CMV-22 Osprey, and the Presidential helicopter fleet.