Learn about Aeronautics

Watch a fascinating and informative documentary that profiles one of America's greatest military aircraft: the B-2 stealth bomber. In this segment you'll learn about aeronautics.

Male Speaker: When air approaches a wing, it is forced in two directions; up and down. This creates a high pressure area above the forward portion of the wing and below the wing. As the wing slopes away a low pressure area is formed above the remainder of the wing. This low pressure area lifts the wing up. In addition the high pressure below the wing pushes it up. Capt. Ryan Huckabay: It's all about lift and drag. An aeroplane has wings what those are and other word for them is airfoils as air travels over the wing, it creates a pressure differential between the top of the wing and the bottom of the wing and what that produce is lift as the low pressure seeks a high pressure area. Male Speaker: Traditionally shaped aircraft have two large wings supporting a central fuselage stabilized at the rear with a horizontal stabilizer and a vertical stabilizer or tip. Although advances in computer technology have allowed the fuselage to be more efficient it still produces a great deal of drag. This drag not only decreases performance in terms of speed it also requires large wings and engines burning lots of fuel to lift it off the ground and to keep it there. The reduction of fuselage drag combined with an overall increase in lift is the flying wings' primary advantage. The flying wing is also called a lifting body because the body of the plane does just that. Capt. Ryan Huckabay: The advantages to the wing design to the flying wing design over a traditional aircraft are the replacement of that fuselage with more wing so that creates a bigger surface area of wing which translates into a more lift. Male Speaker: Instead of the traditional arrangement the entire volume of the aircraft is contained within the wing. This eliminates fuselage drag and vastly increases overall lift. The difficulty with flying wings has always been stability. Jack Northrop's flying wing was notoriously dangerous and in theory all flying wings share the same inherent risks. A flying wing is stable in terms of pitching up or down or banking left or right. What the flying wing doesn't inherently counteract is yaw and yaw is the tendency of applying to fish tail left or right. On traditional aircraft, the horizontal and vertical stabilizers are mounted on the tail of the plane placing a great deal of control at the end of what is essentially a long lever. A flying wing doesn't have this lever and thus control surfaces must be far more complex. To compound the control complications on the B-2 there are no vertical surfaces whatsoever. Northrop's YB-49 and XB-35 both had vertical stabilizers; the B-2 however doesn't have this luxury. Most bombers have enormous tails which act like billboards when struck by radar waves. Instead the B-2 controls its roll pitch and yaw all with the same set of complex control flaps on the -- of the wing. Lt. Col. Steve Bash Basham: For everyone who have seen a B-2 the one thing that you notice for alphabet that's missing is that vertical tail, then vertical stabilizer without computers there is no way we could fly, we could fly the B-2. The computers actually sensing the environment around the aircraft as well as the pilot inputs and keep the aircraft going. Capt. Ryan Huckabay: The flight control computers sense the air loads using things like those air data ports over there that sense static pressure and air dynamic pressures on the aircraft, what is angle of attack is when its sides lift, all those inputs go into a flight control computer, the flight control computer then makes adjustments to the flight controls faster than the pilot would by hand enabling the flight control computers really produce that stability that we lost with the tail. Male Speaker: The outermost control surfaces on the B-2 are the rudders which also function as breaks. Twin flaps move in conjunction to make the bomber yaw left or right. When the flaps on both sides are extended both up and down they act as a speed break. These flaps are in effective when fully closed, so during normal flight they are left slightly open. This does increase the radar signature and during combat operations the B-2 is flown with the rudders fully closed moving in board from the rudders is where the elevons are located. Elevons are a combination of ailerons and elevators. Ailerons and elevators control the pitch and roll of an aircraft. On most planes the ailerons are located on the trailing edges of the wings while the elevators are located on the horizontal stabilizer. The ailerons act in opposite directions of one another to roll the aeroplane while the elevators act together to pitch the plane up or down. On the B-2, the elevons perform both functions through combinations of movement. If all the elevons pitch up or down the aircraft will pitch in the opposite direction. If the left elevons pitch up while the right elevons pitch down, the bomber will roll to the left and vice versa. The coordination of all these flaps is the job of an amazing technology known as fly-by-wire. Capt. Ryan Huckabay: Fly-by-wire takes inputs from the pilots and other aircraft sensors, feeds them into a series of computers which then produce an output to a hydraulic actuator which moves the flight controls force. Male Speaker: Because the computer's job is to make the aircraft perform according to the pilot's controls any external forces that act on the aircraft such as wind dusts are counteracted automatically by the computer. This allows the B-2 and other fly-by-wire aircraft to maintain the traditional controls and maneuvers common to all aircraft despite its radical design. The radical design of the B-2 represents a step forward in all arenas of aircraft design. The result of fly-by-wire is that while pilots compare flying a B-2 to driving a bus the B-2 handles more like a sports car.