Tanker aircraft and their crews help put the “superior” in U.S. air superiority.
Tankers enable fighter and bomber aircraft to reach targets further into enemy territory, airlift aircraft to haul equipment across the globe and surveillance aircraft to loiter for extended periods over critical airspace. Tankers are also capable of transporting cargo, people and equipment to bases almost anywhere in the world.
Each time a C-17 delivers critical supplies or food, a B-2 bomber targets an insurgent safe house, or an F/A-18 sets out on a mission to provide aerial support, the tankers are there behind the scenes, flying multiple sorties to get those planes the fuel that they need to complete their missions.
Yet many people still don’t truly understand what a tanker is, and how it does its job. Aerial refueling can be described as an aerial ballet conducted at 30,000 feet where thousands of pounds of fuel pass between two aircraft traveling at more than 450 mph. Tanker missions require detailed planning and constant training to ensure things go off without a hitch. Most tankers are based on the airframes of commercial jetliners, modified to carry hundreds of thousands of pounds of fuel in addition to pallets of cargo.
Experienced tanker crews make it look easy, but fighter, bomber and airlift pilots will tell you that there’s no room for mistakes.
When the receiver aircraft enters the preplanned air refueling track, the tanker aircraft turns to fly directly toward the incoming plane at closure rates approaching 900 knots. At a predetermined point the tanker executes a 180-degree turn to roll out in a position one mile ahead of and 1,000 feet above the receiver aircraft. Then the thirsty aircraft gets the signal to climb into position a mere 20 feet behind the tanker aircraft, traveling between 190 and 320 knots indicated airspeed (KIAS).
There are two basic refueling methods: (1) a telescoping “flying boom” attached to the rear of the aircraft, or (2) a flexible “hose and drogue” system mounted either to fuel pods on the wings or at the rear of the aircraft.
Invented by Boeing in 1948, the flying boom system enables a tanker to transfer over 900 gallons of gas per minute to an aircraft, a rate which could fill a typical automobile gas tank in just over one second. This rate is essential when refueling bombers or long-haul airlift jets. Why is it called the flying boom? Because the boom operator controls two small wings on the boom that literally fly it to the fuel receptacle on the receiver aircraft. Boeing’s KC-7A7 tankers are the only aircraft to use fifth-generation boom technology.
On the other hand, the hose and drogue system simply extends or trails a 70-90 foot hose with an aerodynamic basket behind the aircraft, positioning it directly in front of the receiver aircraft. The hose and drogue method delivers the fuel at a much slower rate, between 400 and 600 gallons a minute, and is typically used to refuel Navy and Marine Corps fighter aircraft.
While the fuel is passing between the two aircraft, they fly on a fixed path with the tanker responsible for the safe navigation of both aircraft. After refueling, the aircraft separate and continue their missions.
Boeing is confident that the KC-7A7 is the best option for the new United States Tanker.