getting to grips with aircraft performance 如何掌握飞机性能 2(6)

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Thrust available 8 seconds after initiation of thrust control movement from minimum flight idle to TOGA thrust

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Gear extended

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Slats and flaps in landing configuration (CONF 3 or FULL)

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1.13 VS1g ≤ V ≤ 1.23 VS1g and check that V ≥ VMCL.

3.3.2.2. Requirements
The minimum gradient to be demonstrated is 3.2% for all aircraft types.
N engines
TOGA thrust

For all Airbus aircraft, this constraint is covered by the approach climb requirement. In its operational documentation (FCOM), Airbus publishes the maximum weight limited by the approach climb gradient only. Landing climb performance is found in the AFM.

3.4. External Parameters Influence
3.4.1. Pressure Altitude
Approach speed is equal to 1.23 VS1g. But, the corresponding TAS increases with the pressure altitude.
PA ê. ρ ì. TAS .

Consequently, the landing distance will also increase.
TOGA thrust, used for go-around, decreases when pressure altitude increases.
PA . . engine thrust .
Therefore, in the event of a go-around, a decrease in engine thrust implies a decrease in the air climb gradients, which means that:
.landing distance . .PA . .. .
air climb gradients
.

3.4.2. Temperature
Engine thrust decreases when the temperature passes the reference temperature. Therefore, in case of a go-around, the air climb gradients will decrease.
 Temp . . go-around air climb gradients  .
3.4.3. Runway Slope

From a performance standpoint, an upward slope improves the aircraft’s stopping capability, and, consequently, decreases landing distance.
Upward slope . Landing distance .
Downward slope . Landing distance .

3.4.4. Runway Conditions
The definition of runway conditions is the same as for takeoff. When the runway is contaminated, landing performance is affected by the runway’s friction coefficient, and the precipitation drag due to contaminants.
Friction coefficient . . Landing distance .
Precipitation drag . . Landing distance .

Depending on the type of contaminant and its thickness, landing distance can either increase or decrease. So, it is not unusual to have a shorter ALD on 12.7 mm of slush than on 6.3mm.
3.4.5. Aircraft Configuration
3.4.5.1. Engine air bleed
Engine air bleed for de-icing or air conditioning, implies a decrease in engine thrust.
 As a result, go-around air climb gradients will decrease.
Engine air bleed ON . air climb gradients  .
3.4.5.2. Flap setting
An increase in flap deflection implies an increase in the lift coefficient (CL), and in the wing surface. It is therefore possible to reduce speed such that the aircraft will need a shorter distance to land (VS1G CONF FULL < VS1G CONF 3).
When wing flap deflection increases, landing distance decreases.
　
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