Sizing for Landing Distance

The most critical case is when an aircraft must land at its maximum landing weight of 0.95 MTOW. In an emergency, an aircraft lands at the same airport for an aborted takeoff, assuming a 5% weight loss due to fuel burn in order to make the return

W/S (FPS – lb/ft2)

40

50

60

70

80

W/S (si-N/m2)

1,915.9

2,395.6

2,874.3

3,353.7

3,832.77

T/ W (nondimensional)

0.180

0.225

0.270

0.315

0.360

Computing and listing in tabular form:

circuit. Pilots prefer to approach as slow as possible for ease of handling at landing. For this class of aircraft, the approach velocity, Vapp (FAR requirement at 1.3 Vstau) is less than 125 kts to ensure that it is not constrained by the minimum control speed, Vc. Wing CLstaii is at the landing flap and slat setting.

For sizing purposes, an engine is set to the idle rating to produce zero thrust.

Vstall = V[(0-95W/Sw)/(0.5 x P X Cbstall)]

Vapp = 1-3 Vstall

Vapp = 1.3 x J[(0.95W/Sw)/(0.5 x p x Cum)] = 1.793 x *J[(W/Sw)/(p x Cbstall)]

At approach:

or (Vapp)2 x Cbstall = 3.211 x (W/Sw)/P

or (W/Sw) = 0.311 x P x (Vapp)2 x Cbstall

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