9
AERODYNAMIC CHARACTERISTICS
The C-130 is a cantilever high-wing monoplane with a high aspect ratio wing with a tapered
trailing edge. The tapered trailing edge reduces wing structural weight by concentrating area, and
hence lift, inboard, while maintaining the efficiency of a high aspect ratio. The wing’s airfoil
section is a conventional camber airfoil with good low speed lift production.
The high wing is necessary to provide ground clearance for the propellers. This has the
advantage of locating the engine inlets well above the ground, providing excellent FOD
resistance for operations on unimproved surfaces.
By bathing part of the wing in the wake of the propeller, the wing is able to achieve higher lift
coefficients than would otherwise be possible. With the flaps in the takeoff position (50%), the
maximum lift coefficients are:
Power off: 2.2
Power on: 3.4
Compare these values with the B727 at flaps 40º, which has the highest lift coefficient for a non-
powered lift jet transport at 3.0. The C-130 takes advantage of the higher lift coefficient for short
field takeoffs.
Power off, the C-130 has benign stall characteristics with sufficient warning via natural airframe
buffet. Buffet is noticeable 4 to 15 % above the stall speed, progressing to moderate to heavy
buffet at the stall. Stall is characterized by either a pitch down or mild roll-off, depending on how
the power is set. Power ON stalls can result in very low indicated airspeeds and high pitch
attitudes, which can result in unusual attitudes.
The horizontal tail is fixed, with pitch control provided by an elevator. As a result of the fixed
horizontal stabilizer, the aircraft has a relatively narrow center of gravity range that varies with
weight.
Laterally, the aircraft is controlled with conventional ailerons located on the outboard trailing
edge of the wing. The ailerons produce noticeable adverse yaw that increases as airspeed
decreases. Because of the high wing, the aircraft has excellent lateral stability (dihedral effect).
Because of the propeller diameter, the engines are located relatively far out on the wing. As a
result, the aircraft has a large vertical tail and powerful single surface rudder to account for
engine failures. The Dutch roll mode is well damped throughout the aircraft’s normal envelope.
One unique characteristic of the C-130 is the power effects from the propeller. Longitudinally,
the aircraft pitches up when the inboard throttles are advanced and pitches down when the
inboard throttles are retarded. With flaps UP, the outboard throttles have little effect on pitch
trim. With flaps in the landing position (100%), advancing the outboard throttles causes a pitch
down and retarding the throttles causes a pitch up.
All of the propellers turn clockwise when viewed from the rear, resulting in non-symmetric flow
around the airframe. As a result, in almost all cases, the No 1 (left outboard) engine/propeller is
the critical engine for performance and controllability.