Page 86 - Planning and Design of Airports

58 Airp o r t Pl anning

Wingspan

Wheel tread or track
Front View

Length

Maximum height

Nose Main gear
gear
Wheelbase
Side View
FIGURE 2-1 Aircraft dimensions.

main landing gear. The wheelbase and wheel track of an aircraft
determine its minimum turning radius, which in turn plays a large role
in the design of taxiway turnoffs, intersections, and other areas on an
airfield which require an aircraft to turn.
Turning radii are a function of the nose gear steering angle. The
larger the angle, the smaller the radii. From the center of rotation the
distances to the various parts of the aircraft, such as the wingtips,
the nose, or the tail, result in a number of radii. The largest radius is
the most critical from the standpoint of clearance to buildings or
adjacent aircraft. The minimum turning radius corresponds to the
maximum nose gear steering angle specified by the aircraft manufac-
turer. The maximum angles vary from 60° to 80°, although for design
purposes a steering angle of approximately 50° is often applied.
The turning radius of an aircraft may be expressed using the fol-
lowing formula:
R = b tan (90 − b) + t/2 (2-1)
180° turn
where b = wheelbase of an aircraft
t = wheel track of the aircraft
b = maximum steering angle