Boeing KC-46 Pegasus In-flight Refueler / Aerial Tanker Aircraft
The Boeing KC-45 beat out the EADS Airbus 330 submission the second time around to win the KC-X tanker competition for the United States Air Force.
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The Boeing KC-46 was selected to replace the aging line of Boeing KC-135 "Stratotankers" through the KC-X program - a competition initially won by EADS/Northrop Grumman. The KC-46 will be a fully-modernized aerial tanker primarily utilized by the United States Air Force and is expected to enter service within the next five years in quantitative numbers. The KC-46 airframe will feature new technologies as found on the Boeing 787 Dreamliner passenger airliner as well as qualities akin to heavy service military transport aircraft. This will allow the KC-46 the ability undertake roles beyond refueling such as cargo transport and MEDEVAC. The aircraft is expected to service multiple fixed-wing types from the USAF, USN and USMC as well as NATO and US-allied nations including large strategic bomber types such as the Boeing B-52 "Stratofortress".
When an initial USAF initiative to acquire Boeing KC-767s aerial tankers fell aground in 2003, a new endeavor was born to develop a new dedicated tanker aircraft through the "KC-X" program in 2006. Both Boeing and EADS/Northrop (on behalf of Airbus) threw their hats into the ring in the hopes of netting the lucrative long-term $40 billion defense contract. Boeing eventually offered their KC-767 while EADS/Northrop delivered their A330 MRTT (this as the "KC-30"). The United States Department of Defense formally selected the EADS/Northrop A330 MRTT/KC-30 proposal and marked the type for development as the "KC-45A" in February of 2008.
The selection of the French Airbus 330 spurred Boeing to action to which the American concern filed a formal protest to American authorities and took their outrage to the public square to help gain a larger audience of favor. The US Government Accountability Office (GAO), citing several miscalculations on the part of the USAF during the initial proposal review and subsequent selection, sided with Boeing and restarted the KC-X bidding process anew.
In the second round of fighting, Boeing resubmitted their KC-767 while EADS - now going it alone without Northrop Grumman support - once again delivered their Airbus A330 proposal. The original selection was overturned in favor of the American-based KC-767 which was formally selected as the winner on February 24th, 2011. For the USAF inventory, the KC-767 is redesignated as the "KC-46A" and, at its core, remains essentially a modernized and militarized version of the original Boeing 767 passenger airliner that began service back in 1982. However, the KC-46 will bring along a new KC-10 style refueling boom as well as cockpit features of the new Boeing 787 "Dreamliner". The initial phase of the KC-46 program will include an "Engineering and Manufacturing Development" portion with a first flight scheduled for sometime in 2014. The USAF intends on procuring some 179 total KC-46 aerial refueling tankers for its current inventory, allowing the release of many of its KC-135 Stratotankers (803 produced since 1957).
Externally, the KC-46 mimics much of the conventional Boeing design philosophy with its streamlined fuselage swept wing surfaces. The cockpit flightdeck is fitted to the extreme forward end of the tubular fuselage with framed windscreen windows allowing for adequate viewing out of the cockpit. The wings are low-mounted onto the fuselage and swept rearwards at 34-degree angles with noticeable dihedral when viewed from the forward profile. The fuselage tapers to a point at the rear of the empennage to which a conventional tail wing plan is affixed. This includes a tall, wide-area vertical tail fin (clipped at its tip) as well as a pair of horizontal tailplanes canted slightly upwards. The undercarriage consists of two main landing gear legs near the wingroots and a nose landing gear leg under the cockpit. The main legs sport four wheels while the nose leg is completed with a standard pairing. There are three rectangular access doors along the fuselage sides for crew and passengers alike. The KC-46 features a standard seating arrangement for 15 operational personnel which include two pilots and the Aerial Refueling Operator (ARO). Maximum take-off weight for the KC-46A is listed by the USAF at 415,000lbs while its fuel capacity is 212,300lbs. Maximum transfer fuel load is listed at 207,670lbs.
Design of the KC-46 is such that the type can be used to fuel any current and near-future US military (and allied) fixed-wing aircraft set up to receive in-flight refueling from an aerial tanker. Fuel delivery is via an updated KC-10-style extending boom assembly as well as a centerline drogue in addition to a pair of underwing aerial refueling pods (these mounted outboard of the engine nacelles). The drogue and underwing pods are designed specifically for use with aircraft that field an integrated refueling probe in their design. All told, the KC-46 can refuel up to three different aircraft types simultaneously thanks to its well-thought out and proven fuel delivery system and design.
The aircraft line will be powered by a pair of Pratt & Whitney PW4062 series high-bypass turbofan engines of 62,000lbs thrust each, these contained in streamlined nacelles slung under each wing. Top speed is 570 miles per hour with a cruise speed of 530 miles per hour. Range is listed at 6,385 miles with a service ceiling of approximately 40,100 feet.
The internal arrangement of the KC-46 is somewhat flexible in design in that it can be used to fulfill a variety of missions along with its primary refueling role. The internal setup can be revised to include cargo space for up to 18 pallets or passenger seating for up to 58 personnel (as many as 114 if need be according to the USAF). The KC-46 can serve the MEDEVAC role as well by supplying room for up to 58 medical litters and applicable staff through the available specialized medical configuration. Maximum cargo capacity is 65,000 lb.
As of this writing, development of the KC-46 is ongoing though cost overruns were noted in June of 2011, this to be covered by Boeing.
In February of 2014, it was announced that the KC-46 has been given the official name of "Pegasus".
In July of 2015 it was announced that sub-par fuel was introduced into the fuel system of test article EMD2, forcing a delay of its first flight until fall of 2015 (from summer of 2015). Four flyable prototypes are expected by project's end.
A KC-46 prototype achieved a first flight on September 25th, 2015.
In November of 2015 it was revealed that Japan had selected the KC-46A marking the country as the first export customer of the Boeing product. Japan is expected to procure three aircraft to go along with its existing stock of four KC-767J models.
January of 2016 recorded the first fuel transfer from a KC-46A to a receiving F-16C Fighting Falcon aircraft. The tanker aircraft was test aircraft EMD-2. More tests with various other aircraft are slated to follow.
July 2016: A KC-46 has fueled a C-17 transport aircraft with new hydraulic pressure-relief valves added to the KC-46's boom system.
December 2016: The USAF expects the KC-46 to begin production and see operational service sometime in 2017.
May 2017 - USAF authorities revealed that the troubled KC-46 is some months behind schedule. The initial KC-46A is not expected to be delivered until the fall of 2017.