In the midst of its Phase III testing, the KC-46 Pegasus completed yet another milestone. The Air Force’s newest refueling tanker made its first mid-air connection with the B-2 Spirit in the skies over Edwards Air Force Base, Calif., recently.
The Air Force took first delivery of the KC-46 earlier this year, the Global Reach Combined Test Force and the 418th Flight Test Squadron has been at the forefront of the platform’s developmental testing program.
“Testing with the B-2 was a pretty big deal for us,” said Jamie Smith, 418th FLTS lead aerial refueling engineer. “It is the first aircraft that has such a dark paint scheme and it takes up quite a large portion of the Remote Vision System (RVS) screen. We were all really interested to see how the RVS would react with the B-2.”
With the connection with the B-52 last summer, and now the B-2, the KC-46 has successfully connected with two of the three bombers in the Air Force inventory. The Global Reach CTF is working with the 419th FLTS, who is in charge of the 412th Test Wing’s bomber fleet.
“This was a first flight of sorts for both of these aircraft,” said Maj. Matthew Gray, 419th FLTS test pilot and flight commander. “Never before has a flying wing refueled behind the KC-46 and as such, we tested unique aerodynamic influences while proving system capabilities.”
Gray serves as the B-2 flight commander and said the mission presented unique challenges and important engineering data. The data gathered from the pairing during the developmental testing phase will impact how the KC-46 operates in the near future. Engineers are looking for information pertaining to flight characteristics as well as other data.
“We are looking for data such as the bow-wave effect from the tanker on the receiver and how it affects receiver handling qualities, boom handling qualities, whether the visual reference indications are satisfactory to both aircrews, if the two aircraft are mechanically compatible: no nozzle binding during contacts, if the fuel systems are compatible with one another, and, determine the aerial refueling envelope; altitude and airspeed,” Smith said.
The B-2’s distinctiveness combined with the new KC-46 platform offers unique challenges for flight crews and engineers.
“The flying wing design of the B-2 poses unique challenges to the flying and handling qualities of the tanker-receiver pair,” Gray said. “The up-wash at the leading edge of the flying wing is dynamic compared to the bow wave at the nose of a conventional receiver aircraft. This dynamic airflow environment in close proximity to the horizontal stabilizer of the tanker is something we are looking to understand and characterize throughout all test missions.”
To mitigate the inherent dangers of the mission, teams from both the 418th and 419th squadrons considered safety to be paramount. Both teams were able to openly communicate safety concerns with each other, said Maj. Dan Welch, 419th FLTS test pilot, and it started with, “in depth safety planning and using a well thought out test build up to ensure safety of aircrew and strategic assets, and fostering a culture where all feel comfortable speaking up if a safety concern presents itself.”
“The entire team of engineers and test pilots from both the 418th and 419th collaborated to develop the safety plan and buildup test approach that was integral in the success of this mission,” Gray said. “The expertise from both organizations in their respective platforms and in-test conduct was apparent in planning and displayed in execution.”
The testing follows a heritage safety-buildup process where the tanker-receiver pair build out from the center of an altitude/airspeed/configuration envelope, defined by legacy tanker and simulation data. Engineers then incrementally test the handling qualities of the individual aircraft and then build to the handling qualities of the pair, said Rachel Johnson, 418th FLTS flight test engineer for the KC-46/B-2 certification test program.
“This process allows the test team to thoroughly evaluate the dynamics of the pair during aerial refueling and is our primary mitigation to most dangers; mid-air collision, boom strike outside the air-refueler receptacle, and fuel over pressurization, inherent to air-refueling testing,” Johnson said. “Additionally, the 418th FLTS tests using an airborne control room who are actively monitoring instrumented test parameters and are able to make real-time decisions.”
The KC-46 further strengthens the Air Force’s bomber fleet by enhancing their capability providing improved support to the Warfighter.
“The KC-46 provides significant added capability over the workhorse of the tanker fleet, the KC-135. It is configured all the time to configure both boom (U.S. Air Force) and drogue (U.S. Navy, foreign) receivers, whereas the KC-135 can generally only refuel one type or the other on a given sortie,” said Maj. Jacob Lambach, 418th FLTS flight test pilot. “It has the capability to carry up to 18 pallets of cargo, versus six for the KC-135, which is especially helpful when moving both aircraft and their support personnel and equipment across the ocean.”
The KC-46 enhances the AF’s Global Reach and Strike capabilities by providing the reliability of a new aircraft coupled with a stable platform to fly behind and will reduce fatigue flying behind a tanker with a large boom envelope, Welch said.
While the B-2 pairing tests are still ongoing, plans are now being developed to pair the KC-46 with the B-1, Johnson said. And according to the test pilots, the success of the first KC-46 and B-2 pairing adds to the history of firsts here at Edwards.
“It’s very exciting to be part of a flight test first. But with the KC-46 program, nearly every sortie we do is a first in some way, shape, or form,” Lambach said. “Some, like the first contact with a B-2, are more exciting than others. To some degree we become numb to it, but each time we go fly, we realize that we’re going to do something that no one has ever done before. It is a privilege and an honor, and requires us to be on the top of our game.”