Maneuvering speed
Encyclopedia
In aviation, maneuvering speed is the maximum speed where full, abrupt control movement in the pitch axis will result in an aerodynamic stall
of the aircraft prior to exceeding the design load limit. It has been widely misunderstood that flight below maneuvering speed will provide total protection from structural failure
. See American Airlines Flight 587
. Due to this accident a CFR Final Rule was issued effective October 15, 2010 clarifying this misconception . It is normally designated as VA in flight manuals, but is not typically shown on most airspeed indicator
s. VA is the calibrated design maneuvering airspeed.
In the context of air combat manoeuvring (ACM), the maneuvering speed is also known as corner speed or cornering speed.
With full elevator
deflection at maneuvering speed, an aerodynamic stall
will occur, reducing or eliminating lift
forces before damage can occur to the aircraft. To increase lift of a given wing, the angle of attack, air density, or the airspeed must be increased. The wing of an aircraft stalls at a specific angle of attack, regardless of airspeed. However, the higher the airspeed, the more lift the wing is capable of producing, and at a certain airspeed it is capable of producing more lift than it can support structurally. The declared maneuvering speed is based on the aircraft's maximum gross weight. At lower weights, maneuvering speed is always lower.
Hypothetically, if an aircraft were flying at a weight equal to its maximum structural load, it would be flying at both stall speed for that weight and maneuvering speed, with no excess angle of attack and lift available to accelerate the aircraft upward. At lower weights, and the same air speed and air density, the aircraft would be flying at a lower angle of attack, well below of stalling condition, and therefore with an excess lift available which could not be structurally supported. Therefore, as gross weight is decreased, maneuvering speed also decreases.
The maneuvering speed decreases as the aircraft's weight decreases from maximum takeoff weight because the effects of the aerodynamic forces become more pronounced as its weight decreases. The flight manuals for some aircraft (such as the Piper Cherokee
) specify the design maneuvering speeds for weights below the maximum takeoff weight but sometimes it is left to the pilot to calculate. Using a "Rule of Thumb", the reduction in VA will be half the percentage reduction in aircraft weight. For example if, with only one person on board, weight is 16% below maximum takeoff weight, then VA is reduced by 8%.
The maneuvering speed depicted on a cockpit placard is calculated for the maximum weight of the airplane, but VA for other weights may be found in some POH
s. The formulas used to calculate VA for a lower weight is
, where VA maneuvering speed (at maximum weight), W2 = actual airplane weight, W1 = maximum weight.
Stall
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded...
of the aircraft prior to exceeding the design load limit. It has been widely misunderstood that flight below maneuvering speed will provide total protection from structural failure
Structural failure
Structural failure refers to loss of the load-carrying capacity of a component or member within a structure or of the structure itself. Structural failure is initiated when the material is stressed to its strength limit, thus causing fracture or excessive deformations...
. See American Airlines Flight 587
American Airlines Flight 587
American Airlines Flight 587, an Airbus A300, crashed into the Belle Harbor neighborhood of Queens, a borough of New York City, New York, shortly after takeoff from John F. Kennedy International Airport on November 12, 2001. This is the second deadliest U.S...
. Due to this accident a CFR Final Rule was issued effective October 15, 2010 clarifying this misconception . It is normally designated as VA in flight manuals, but is not typically shown on most airspeed indicator
Airspeed indicator
The airspeed indicator or airspeed gauge is an instrument used in an aircraft to display the craft's airspeed, typically in knots, to the pilot.- Use :...
s. VA is the calibrated design maneuvering airspeed.
In the context of air combat manoeuvring (ACM), the maneuvering speed is also known as corner speed or cornering speed.
With full elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...
deflection at maneuvering speed, an aerodynamic stall
Stall (flight)
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded...
will occur, reducing or eliminating lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...
forces before damage can occur to the aircraft. To increase lift of a given wing, the angle of attack, air density, or the airspeed must be increased. The wing of an aircraft stalls at a specific angle of attack, regardless of airspeed. However, the higher the airspeed, the more lift the wing is capable of producing, and at a certain airspeed it is capable of producing more lift than it can support structurally. The declared maneuvering speed is based on the aircraft's maximum gross weight. At lower weights, maneuvering speed is always lower.
Hypothetically, if an aircraft were flying at a weight equal to its maximum structural load, it would be flying at both stall speed for that weight and maneuvering speed, with no excess angle of attack and lift available to accelerate the aircraft upward. At lower weights, and the same air speed and air density, the aircraft would be flying at a lower angle of attack, well below of stalling condition, and therefore with an excess lift available which could not be structurally supported. Therefore, as gross weight is decreased, maneuvering speed also decreases.
The maneuvering speed decreases as the aircraft's weight decreases from maximum takeoff weight because the effects of the aerodynamic forces become more pronounced as its weight decreases. The flight manuals for some aircraft (such as the Piper Cherokee
Piper Cherokee
The Piper PA-28 Cherokee is a family of light aircraft designed for flight training, air taxi, and personal use. It is built by Piper Aircraft....
) specify the design maneuvering speeds for weights below the maximum takeoff weight but sometimes it is left to the pilot to calculate. Using a "Rule of Thumb", the reduction in VA will be half the percentage reduction in aircraft weight. For example if, with only one person on board, weight is 16% below maximum takeoff weight, then VA is reduced by 8%.
The maneuvering speed depicted on a cockpit placard is calculated for the maximum weight of the airplane, but VA for other weights may be found in some POH
POH
POH may refer to:* pOH, a measure of the concentration of hydroxide ions* Power-On Hours, the length of time, in hours, that electrical power is applied to a device* Port Henry , New York, United States; Amtrak station code POH...
s. The formulas used to calculate VA for a lower weight is
, where VA maneuvering speed (at maximum weight), W2 = actual airplane weight, W1 = maximum weight.