One of the KC-46 Pegasus’ key features was successfully tested recently at Edwards Air Force Base, Calif.
The Wing Aerial Refueling Pods (WARPs) were successfully tested with an AV-8B, F-18D, and F-18G. The WARPs allows the Pegasus to simultaneously refuel two aircraft at the same time, which makes it a force multiplier.
“With WARPs, the KC-46 will be able to refuel two fighter aircraft at the same time; as opposed to a centerline drogue system, where only one aircraft can refuel at a time,” said Maj. Jacob Lambach, KC-46 experimental test pilot, 418th Flight Test Squadron. “Fighter pilots usually show up in pairs and each has to watch and wait while their wingman refuels. Fighters’ combat mission isn’t to sit behind the tanker; it’s to fight. If we can refuel them both at the same time, they each only spend half as much time ‘out of the fight.’”
Following successful completion of the connections, engineers have a multitude of data to review before it is certified by the Aerial Refueling Certification Agency. Engineers have to evaluate the performance of WARPs prior to fielding the capability to the warfighter; this includes looking at the free air stability, the hose reel response, the fuel system, and the human factors.
“The free air stability of the hose and drogue are evaluated during extension, while fully extended, and during retraction to ensure a safe environment for the receiver,” said Nathan Montoya, aerial refueling engineer, 418th FLTS. “The receiver handling qualities are evaluated in the tanker wake environment and any differences between the left and right WARPs are noted. The WARPs hose reel response (how the system takes up hose slack) is evaluated at various contact rates, and hose lengths to ensure no excessive slack builds up which can damage the receiver. The fuel system is evaluated to determine if the fuel pressures and fuel flow rates that are being provided to the receiver are acceptable.”
Additionally, the hose markings, signal lights, and tanker lighting are evaluated for proper visual cues and operator situational awareness. These evaluations are done at various altitudes, airspeeds, tanker gross weights, and time of day to ensure the system responds properly, safely, and any pertinent warnings, cautions, and/or notes are documented for fleet operations, he said.
From a pilot’s perspective, not much changes, Lambach said. Their goal is still to fly the aircraft as smoothly as possible to make the boom operator and receiver pilot’s job easier. Lambach explained that for the boom operator and receiver pilot, the difference between boom air refueling and WARPs is drastic.
“In boom air refueling, the receiver pilot flies to a defined area behind the tanker aircraft, then the boom operator is responsible for the precise act of connecting the two aircraft,” he said. “With WARPs, the boom operator deploys and monitors the basket, but the receiver pilot is responsible for the final act of connecting the aircraft.”
The WARPs use a drogue chute system for refueling. The receiving pilot then has to make small corrections to line up the drogue basket to the receiver’s probe. The airflow around the receiver aircraft often causes the basket to suddenly move unpredictably, Lambach said.
“Hitting a bullseye is tough; it’s even tougher when the target moves at the last minute,” he said.
Mid-air refueling with multiple aircraft presents other various challenges for the aircrews involved, Montoya added.
“The biggest challenge when testing with dual WARPs is making sure there is always positive communications and situational awareness between the test assets at the same time,” Montoya said. “This is something that is rarely done in test, as boom and centerline drogue operations only refuel one receiver at a time. “
Having three airplanes being able to fly at the same time also provided a logistical challenge, said Capt. Andrew Novak, KC-46 experimental test pilot, 418th FLTS. Various factors, such as manning and crew availability due to other test missions can affect when particular flights can occur.
“The biggest change was the increased coordination and planning required to have three airplanes flying together at the same time,” he said. “At that point in the testing, we already knew both aircraft could safely receive fuel on either WARP. It was just a matter of refueling two aircraft at the same time. Both aircraft were successfully able to fill up.”
“A larger effort was put in the preplanning process to focus on how the dual WARP testing would be executed to maintain a safe test environment and ensure the proper data is collected,” Montoya said.
“It’s an honor to be participating in this testing and being able to provide the operators with the necessary information to utilize the KC-46 WARP system to the max extent possible. It has been a pleasure working with all the U.S. Air Force pilots and boom operators as well as Navy pilots and engineers throughout all the testing.”
Lambach said he felt privileged to support the warfighter through the KC-46 testing and to add to the Edwards legacy of test.
“It’s a privilege to be involved with testing a system that will help the warfighter,” Lambach said. “The KC-46 brings some unique new capabilities to the fight, but before we can really benefit from those, we have to prove that it has all the capabilities that legacy tankers such as the KC-10 and KC-135 have.”