Topic of the Day: Takeoff performance review
Weight is the most influential factor in Take Off and Landing Distance. It increases TAS and IAS. Thus V1 decreases as gross weight increases.
Takeoff into a headwind allows the aircraft to reach T/O speed at a lower groundspeed, Thus reaching critical engine failure indicated airspeed at a lower groundspeed.
Accelerate-go distance—the distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1 and continue the takeoff on the remaining engine(s). The runway required includes the distance required to climb to 35 feet by which time V2 speed must be attained.
Accelerate-stop distance—the distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and abort the takeoff and bring the aircraft to a stop using braking action only (use of thrust reversing is not considered).
Takeoff distance—the distance required to complete an all-engines operative takeoff to the 35-foot height. It must be at least 15 percent less than the distance required for a one-engine inoperative engine takeoff. This distance is not normally a limiting factor as it is usually less than the one-engine inoperative takeoff distance.
Balanced Field Length–this means that the distance shown for the takeoff will include both the accelerate-go and accelerate-stop distances. One effective means of presenting the normal takeoff data is shown in the tabulated chart.
Critical field length—the minimum runway length plus clearway and/or stopway, may be longer than balanced field length 115% of all engine take off distance.
Clearway, an area beyond the runway 500’ wide with no obstacles.
Stopway, an area beyond the departure end that will be able to withstand the weight of the aircraft in order to stop (aborted takeoff).
Effect of gross weight, pressure, altitude, temperature, humidity, wind and ground effect of takeoff and landing performance
High, Hot, Humid, and Heavy are four factors that increase take off and landing distance. An increase in any one will increase Take Off distance and increase landing distance.
As airport elevation increases, the takeoff run required before V1,VR and V2 increases; the stopping distance from V1 increases.
A headwind will decrease takeoff distance and decrease landing distance. A tailwind will increase Take Off distance and increase landing distance.
The landing speed, in terms of TAS and Ground speed, for a particular weight will increase as altitude is increased. IAS will remain same.
Friction and aerodynamic braking effectiveness—factors affecting
Aerodynamic breaking is the most effective means of dealing with a hydroplaning situation. Use of flaps, AOA, spoilers, reversers ect. will produce more desirable results than breaking.
Tire speed limitations and break temps can be a factor.
Hydroplaning
Dynamic: occurs when standing water on runway and determined to be about 9 times the square root of tire pressure in psi.
Viscous: occurs as a result of viscous thin water film that tire cannot penetrate. Can happen at slow speeds and requires a smooth surface.
Reverted Rubber: occurs when a pilot locks the breaks and the frictions creates heat that causes a steam layer between the tire and wet runway.
Weight has no effect on the velocity an airplane hydroplane.
