Lockheed Hercules C-130H User manual

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C-130H “Hercules”
Qualification/Evaluation Guide
418 FLTS
Oct 2012

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Intentionally Left Blank

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CHAPTER 1
AIRCRAFT DESCRIPTION
GENERAL
The C-130, manufactured by the Lockheed Company, is a medium range tactical transport
powered by four T-56 turboprop engines. The C-130 can operate from short, unprepared
surfaces, can back up under its own power, and has been adapted for many missions, with cargo
hauling, airdrop, and medical evacuation as the most common. The aircraft has been in
continuous production since 1955 with over 2,300 examples delivered by 2009.
Development of the C-130 was a direct result of the Korean War, as the propeller powered
transports left over from WW II were unable to accomplish short take off and landings with
useful loads. A development contract was awarded to Lockheed, who produced the YC-130
prototype that first flew on 23 August 1954 from Burbank to Edwards AFB. Unlike transports
derived from passenger airliners, the C-130 was to be designed from the ground-up as a combat
transport with loading from a ramp at the rear of the fuselage. While the appearance of the C-130
was unremarkable, the design was innovative in introducing 3000 psi hydraulic boosted flight
controls, turboprop propulsion, and the high lift capabilities of the Lockheed-Fowler type wing
flaps.
DIMENSIONS
Wing span .............................................................................132 feet
Length .....................................................................................98 feet
Tail height ...............................................................................38 feet
WEIGHTS
Maximum combat weight ........................................ 175,000 pounds
Max normal start taxi...............................................155,000 pounds
Max landing weight ................................................. 155,000 pounds
Normal landing weight ............................................130,000 pounds
Representative operating weight................................88,000 pounds
Fuel capacity ..............................................................61,364 pounds
While not considered a true short takeoff and landing (STOL) aircraft, the C-130 can be operated
from runways as short as 3,000 feet, and can operate from unimproved surfaces. At weights less
than 135,000 lbs, up to 100 passes are permissible on an unimproved surface with a California
bearing ratio of 6 – soil consistency of a golf course fairway. The turboprop engines have
excellent foreign object damage (FOD) tolerance, and allow the aircraft to back up on its own
power, which is important for operations at airfields with limited ramp space. The low cargo
floor and ramp allow the aircraft to easily loaded, to include driving vehicles directly into the
cargo compartment and combat offloads – offloads of palletized equipment using the aircraft’s
own power.
The aircraft is normally flown with a crew of four; pilot, copilot, flight engineer, and loadmaster.
The flight engineer runs the aircraft systems, and the loadmaster runs the cargo compartment, to
include loading, unloading, center of gravity and weight calculation, passenger minding, and
airdrop rigging.

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The design has proved versatile. The aircraft has been flown from both poles and has landed and
taken off from an aircraft carrier. Some of the C-130 missions include cargo hauling, air drop,
bombing, air-to-ground gunnery, drone launching, photo mapping, missile tracking, covert
ingress and egress, air evacuation, airborne battle control, electronic warfare, and television
broadcasting. The C-130 can carry 90 troops (life raft capability limits the number to 80 for
overwater flights) or 64 paratroopers. The record passenger count for the C-130 is 452 set during
the evacuation of Vietnam. The C-130A aircraft used on this mission is prominently displayed at
the main gate at Little Rock AFB, AR.
RANGE-PAYLOAD
The C-130 is the primary tactical airlifter for the USAF, meaning that the C-130 mission is to
deliver materiel within (inter-) the theater of operations. The strategic airlift (deploying forces
from the CONUS to the theater) is the responsibility of the C-5, C-17, and Civil Air Reserve
Fleet (CRAF). The following is a range-payload diagram for selected air-drop capable mobility
aircraft. These data represent theoretical maximum performance, and do not account for
operational limitations that affect the range-payload of a specific mission (takeoff temperature
and pressure altitude, runway length, required departure climb gradient, maximum landing
weights, etc). For example, the two engine aircraft (C-160, C-27J) appear to have better range
performance than the four-engine aircraft. The better range performance results from their lighter
operating weights (C-160 60,000 lbs, versus C-130 at 82,000 lbs). However, the allowable
takeoff gross weight for the C-160 and C-27J is much more limited by the engine-out climb
gradient than for the four engine aircraft. Under a given set of takeoff conditions, the four engine
aircraft can depart at a significantly higher gross weight, and hence will likely have better cargo
or range capability.
The range-payload comparison makes it clear that the C-130 is ill suited for the strategic airlift
mission. On a flight from California to Hawaii, the C-130 is capable of carrying only about 9,000
lbs. of cargo at a cruise speed of 0.45 Mach, requiring flight duration of 7+45. The range-payload
for the B737-800, a comparably sized turbofan transport currently in production, is also
presented, and gives an idea of the degree to which the C-130 range-performance is
compromised for the military mission (turboprop propulsion, straight wing, large cross section,
cargo handling equipment, and ramp and door).

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Aircraft Nominal Cruise 463L Pallets Cargo Bay (w x h) Passenger/Jumpers
C-17 0.70 – 0.77 18 18 feet x 14 feet 102/102
A400M 0.68 – 0.70 9 13 feet x 12 ft 7 in 116
C-130H 0.43 – 0.50 6 10 feet x 9 feet 92/64
C-160 10 feet x 9 feet 92/61
C-27J 0.35 – 0.50 2 8 ft x 7 ft 4.5 in 68/46
While the C-130 is capable of carrying 42,000 lbs of cargo, at cargo weights above 36,500 lbs,
the aircraft must land with additional fuel in the wings for wing bending relief. At the maximum
cargo weight of 42,000 lbs, the required ballast fuel is 16,000 lbs. This additional fuel must be
considered unusable until the cargo is unloaded, and results in the flat portion in the upper right
hand corner of the C-130’s range payload graph. The C-130J, currently in production, has this
same limitation.
The C-130 is limited to maximum landing weight for assault landings of 130,000 lbs. In a
tactical situation where fuel must be tankered, the allowable cargo rapidly decreases from the
42,000 lbs. maximum.
Because the original fleet of C-130A and B model aircraft were worn out by the end of the
Vietnam war, the advanced medium short takeoff and landing (AMST) program was launched as
replacement for the C-130. David Packard, of Hewlett and Packard, the Secretary of Defense
when the AMST program was launched, believed in competitive prototyping (“Fly-before-you
buy”); contracts were awarded to Boeing and Douglas for two prototypes, the YC-14 and YC-15.
These design goals of the AMST aircraft included improvements on C-130: a 2,600 NM
unrefueled range with a 19-ton payload, a long-range cruising speed of at least 0.75 Mach, and
the ability to operate with a 28,000 pound load from a 2,000-foot-long by 60-foot wide runway
during the mid-point of the mission. Both prototypes included a cargo compartment wide enough

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to accommodate the M60 tank. When the C-130 was designed in the 1950s, the Army had more
infantry than armored division. By the mid-70s, the situation was reversed and C-130 could only
carry between 35 and 55% of the mechanized or armored division’s combat vehicles.
Boeing YC-14
Douglas YC-15
Both aircraft meet the AMST program specifications. But as the Vietnam War ended, strategic
airlift became a higher priority. In 1973, the United States supported Israel with materiel during
the Yom Kippur war. Because of the vast distances (6,500 NM each way), lack of air refueling
capability, and unavailability of enroute support facilities, the C-5s and C-141 of Military Airlift
Command were stretched to the limit. Although the first naval ship brought in more outsized
cargo than had been transported by air in the 19 days before hand, it arrived after the end of the
war. The overthrow of the Shah of Iran and the Soviet Union invasion of Afghanistan, which
placed forces hostile to the US in proximity to the Persian gulf oil fields, caused the US strategic
focus to shift war planning from the Europe and its heavy reliance on prepositioned equipment to
the ability to deploy a large force anywhere in the world. The ability to carry outsized equipment
(helicopters, armored vehicles) became important, as these are high value items and are generally
too expensive to preposition, and cannot be carried by commercial aircraft.
To meet the strategic airlift needs of the US in the early 1980s, the C-5A was rewinged and the
production line was restarted and 50 C-5Bs produced, the C-141A was stretched into the C-
141B, and 60 KC-10s were acquired as tanker with significant cargo capability. The AMST
program morphed into the C-X, a strategic airlifter with tactical capability. Using the Douglas
YC-15 as a starting point, the C-X program resulted in the C-17. While the Army had based its
equipment transportation plans around the C-5, and the C-5 could transport virtually all of the
Army’s divisional equipment, the C-5 proved unable to operate out of austere fields and was not
able to back up under its own power. This meant it was limited to larger airfields, and an
additional means was need to get the equipment forward to the fight. While primarily a strategic
airlifter, the C-17 has impressive tactical capability, due to its powered lift design, ability to
operate on semi-prepared surfaces, and ability back up under its own power. With a given cargo
weight, C-17 runway requirements for takeoff and landing is comparable to the C-130, and the
C-17 can do so after crossing an ocean carrying a M-1 tank. This is the direct delivery mission, a
capability that transcends the division of strategic and tactical airlift.
The C-130As and Bs of Vietnam ended up being replaced by C-130Hs, a modestly improved
design that was in production from 1974 until the arrival of the C-130J in the mid-1990’s. The
continuous acquisition of the C-130 had the unintended benefit that the fleet is of varying age
and will not need to be replaced all at once. Replacing a large fleet is an acquisition challenge,
the best example being the decade long effort to replace the KC-135.

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The C-130 has the advantage over the C-17 in that it is significantly less expensive to operate, at
$2,200/flight hour compared to $8,500/flight hour for the C-17 (FY-10 data from Air Force Total
Ownership Cost database). After the Arab oil embargos of the 1970’s, the relatively low fuel
burn of the C-130 became one of its strongest selling points.
Because of the ubiquitousness of the C-130, US Army brigade combat team equipment has a
design requirement to fit into the C-130. The Army has struggled to design capable armored
vehicles that can meet the cargo hold size and weight limitations of the C-130. The Stryker, a
new class of Army armored vehicles, had a design requirement that it be transported for 1000
NM by the C-130 and arrive ready to fight. While the Army ultimately demonstrated the ability
to transport the 38,000 lbs Stryker in the C-130, the C-130 is often not able to meet the range
requirement, and the vehicle must be fueled and provisioned before it can conduct combat
operations, failing to meet a key operational requirement. Additionally, the C-130 is unable to
carry mine resistance ambush protected (MRAP) vehicles.
The complexity and age of the C-130’s propulsion system design is reflected in fleet reliability,
which is low compared to other AMC aircraft. The following is AMC overall planning
commitment levels (Reference: AMCI 10-202, Mission Reliability Reporting System, Vol 6,
Table A2.2):
MDS Normal Contingency/Surge
C-5 65% 75%
C-17 85% 90%
C-130J 75% 85%
C-130E/H 65% 75%
KC-135 80% 85%
KC-10 80% 80%

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COCKPIT
C-130H1 or H2 Instrument Panel
C-130H3 Instrument Panel

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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.

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When power is advanced, the aircraft yaws LEFT and RIGHT RUDDER must be applied to keep
the aircraft in trim.
The C-130 experiences a marked reduction of directional stability at low dynamic pressures, high
power settings, and at elevated side slip angles. This reduction in directional stability is
manifested to the pilot as a low rudder force gradient (small rudder forces produce large side slip
angles). There are several contributors to this reduction in directional stability, one of which is
the normal force produced by the propellers when the propeller is at an angle to the oncoming
flow:

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Reduction in directional stability at high power settings
The conditions where the reduction in directional stability are most likely to occur are:
Low speed (aerodynamic controls are less effective, control feel is a function of dynamic
pressure)
Flaps 50% (high rudder boost, allows generation of larger side slip angles)
Gear up (Landing gear down is stabilizing)
High power settings (more momentum change across the propeller disk, larger
destabilizing normal force)
Left rudder pedal inputs, right side slip
The primary indication to the pilot of reduced directional stability is the reduction in rudder
pedal force gradient. In some cases only 25 pounds of rudder force are needed to command 25
degrees of side slip. The cockpit side forces that might provide warning to the pilot of high side
slip are too low to be noticeable at the low airspeeds where rudder force lightening is most likely
to happen.
To avoid over control, excessive side slip angles and rudder overbalance (reversal in rudder
pedal forces, aka “rudder lock”), the pilot must anticipate and recognize the low rudder force
gradient. The pilot will experience the rudder force lightening when the rudder pedals begin to
move easily and side slip continues to increase. If the pilot continues with rudder pedal input,
the rudder pedal force will continue to decrease until the rudder floats towards full deflection by
itself. The pilot experiences this as a reversal in rudder pedal force and it is called rudder
overbalance. If rudder overbalance occurs, neutralizing the rudder pedals will not recover the
aircraft. The pilot must actively push on the opposite rudder to bring the rudder back towards
center. If the rudder is not promptly centered, the airplane can reach an extreme side slip, roll to
a high bank angle, and depart controlled flight.

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PERFORMANCE
Excess power is a measure of the ability of the aircraft to accelerate or climb. Specific excess
power (Ps) is the excess power normalized for aircraft weight, allowing the capability of aircraft
at different weights to be compared. Compared to a swept - wing jet aircraft, maximum specific
excess power for a straight - wing turbo propeller aircraft occurs at much slower speeds in the
envelope. The excess power characteristics translate to lower speeds for best angle of climb and
best rate of climb for the C-130 relative to swept -wing jet aircraft.
The following diagrams compare the notional characteristics of a swept - jet aircraft (black lines)
with a straight – wing turboprop aircraft (red lines). This chart shows the differences in total drag
between a swept wing and a straight wing aircraft. A straight wing aircraft has less induced drag
at slower speeds.

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This diagram adds thrust available characteristics from propellers and jet propulsion to the total
drag curves. The propeller has highest thrust at slower speeds, with thrust decreasing as airspeed
increases. The thrust available from a jet aircraft tends to be relatively constant at subsonic
airspeeds:
The following diagram compares the power available and power required between swept – wing
jet aircraft and straight – wing propeller aircraft. The straight – wing propeller aircraft has the
greatest excess power at slower airspeeds relative to swept – wing jet aircraft:

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The contours of constant specific excess power are often presented on a turn performance
diagram. A turn diagram is valid for a single thrust to weight ratio; aircraft weight, configuration,
power setting, and atmospheric conditions (pressure altitude and temperature). A turn
performance diagram presents airspeed (V) versus turn rate (ω), with airspeed on the horizontal
axis and turn rate on the vertical axis. Overlaid on the chart are lines on constant turn radius (R ):
R = V/ω
Additionally, curves of constant nzare overlaid:
Nz = √(1 + V2/(g2R2))
The aircraft envelope, defined on the left hand side by the lift boundary (stall speed) and right
side by maximum airspeed (VMO/VD) is also presented. The top of the aircraft envelope is the
maximum allowable symmetric load factor (nz):

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The following is a turn performance diagram for a C-130H at sea level, standard day. 130,000
lbs with thrust set to 1049° C, with contours of specific excess power overlaid.
The highest specific excess power contours are on the left hand side of the aircraft’s envelope
near the lift limit (stall speed). The minimum sustainable turn radius is at point “B,’ about 1,300
ft (about 12 ship lengths). This is also the point of maximum sustainable turn rate (12°/sec) in
level flight. This results in excellent slow speed maneuverability.
The C-130 maximum effort takeoff operations are a result of its specific excess power
characteristics. Maximum effort takeoff operations are conducted at significantly slower
airspeeds than normal takeoffs to take advantage of the greater specific excess power. The
maximum effort speeds provide for improved climb capability at the expense of safety by, in
some cases, ignoring minimum control speeds. In the C-130, the actual best angle of climb
airspeed (used for clearing obstacles after takeoff) is just above the stall speed. Speeds this slow
are not operationally practical, so some speed increment is used at the expense of climb angle.
The C-130 climbout performance is a marked contrast to a typical swept - wing jet aircraft.
Using the KC-135R as a representative example of a swept - wing jet aircraft, the following is a
diagram of speed/configuration verses climb rate:

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Climb gradient is the proportional to the ratio of climb rate to forward airspeed:
For the KC-135R, the climb gradient for a given configuration (flap setting) increases with
increasing airspeed at slow speeds. This is in contrast to the C-130, where climb rate generally
decreases with increasing airspeed at slow speeds.
Relative to a swept - wing jet aircraft, the C-130 has a much larger difference between best rate
of climb airspeeds and practical cruise airspeeds. This shows up in C-130 cruise step climbs,
where the aircraft is slowed to best rate of climb, the climb is accomplished, and then once level,
the aircraft is accelerated at maximum continuous power until reaching the desired cruise
airspeed. The cruise airspeed is typically at a very low excess power condition:

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An additional area where the C-130 excess specific power characteristics are manifested is
during heavy airdrop malfunction procedures when multiple 28-foot extraction parachutes
deploy outside the aircraft but do not extract the load. The deployed extraction parachutes result
in an extremely high drag condition. The pilot’s procedure for heavy airdrop when multiple 28-
foot extraction parachutes deploy outside the aircraft is to set maximum thrust and slow to
maximum effort takeoff speed. Looking at the specific excess power contours, maximum effort
takeoff speed approximates the region of maximum specific excess power where the aircraft’s
climb rate is maximized:
With multiple 28-foot extraction parachutes deployed outside the aircraft, maximum thrust
will be need to stay aloft or control the descent. The drag produced by the extraction
parachutes should decrease if airspeed is allowed to bleed off. This reduction in drag could
permit level flight or reduce the rate of descent should level flight not be possible. Do not
reduce power to achieve this airspeed change and do not slow below max effort takeoff
speed. Max effort takeoff speed is 1.2 x power on stall speed and provides an acceptable
airspeed margin for zero bank angle.
Slowing to maximum effort takeoff speed is a compromise; it is an easily computed number and
provides some margin above stall.

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ENGINES-PROPELLERS
The C-130 is powered by four T56 turboprops that were developed specifically for the C-130.
They were one of the first turboprops developed in the West. The turboprop is made up of three
main components, a gas generator, reduction gear box, and propeller.
T56 Engine-Gearbox
Turboprops provide gas turbine reliability and power to weight ratios with the good low speed
performance of propellers. Turboprops have a sweet spot at speeds below about 400 knots TAS,
where they provide better fuel efficiency for a given range/payload target relative to turbofan
engines. Turboprop efficiency comes from the propeller accelerating a relatively large amount of
mass flow at a relatively low velocity.
Gas Generator
The gas generator, or “engine,” consists of a compressor, combustion, turbine, and exhaust. In a
turboprop installation, the majority of the power produced by the gas generator is extracted by
the turbine and used to drive the propeller. Because most the energy from combustion is used to
drive the turbines, the residual energy in the exhaust jet is low, and the exhaust jet produces
typically less than 10% of the total thrust.
ESHP = BHP + TJ*V/325*ηP
Where:
ESHP = equivalent shaft horsepower
BHP = brake horsepower, or shaft horse power applied to the propeller
T
J= jet thrust, lbs.
V = velocity, TAS
ηP= propeller efficiency, percent

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Turboprops are rated using power, in units of horsepower (Hp) or kilowatts (KW). For the C-130
with 54H60 propellers under static, standard day, sea level conditions:
ESHP = 4,910 horsepower
BHP = 4,591 horsepower
T
J*V/325*ηP = 319 horsepower
During flight, the T-56 runs at a constant 100% RPM (13,820 RPM), so torque (force times
distance) is proportional to horsepower. The C-130 T-56 installation uses torque as the primary
indication of engine output. The most important operational limitations for the C-130 engine are:
Torque: 19,600 in-lbs. maximum
Turbine inlet temperature (“TIT”): 1083º maximum.
The T56-A-15 engine is flat rated (meaning it gives out a constant 19,600 in-lbs. of torque, until
the ambient temperature reaches a “break” temperature, and then available torque decreases as
temperature increases. Stated another way, at low ambient temperatures the engine is torque
limited by 19,600 in-lbs of torque, and at high ambient temperatures, the engine is TIT
limited.
Reduction Gear Box
In order to obtain the mass flows with a reasonable cross section, the compressor of the gas
generator is required to operate at high RPM (13,820 RPM for the T56). The propeller sees both
the forward velocity of the aircraft and its rotational velocities, therefore the propeller tips
approach the speed of sound well before the aircraft itself. Once the propeller tips approach the
speed of sound, wave drag increases substantially. In order for a turboprop to be efficient over a
practical range of aircraft speeds, the propeller must turn slower than the gas generator. As a
result, there is a need for a reduction gear assembly to reduce the rotation speed of the propeller
relative to the gas generator. The reduction gear box for the C-130 has a ratio of 13.54 to 1, so
the propeller spins at 1,021 RPM at 100% RPM.
Variable Pitch Propeller
The angle of attack of a fixed-pitch propeller, and thus its thrust, depends on the forward speed
of the aircraft and the rotational velocity. A fixed pitch propeller will provide the maximum

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thrust only at a single airspeed. By varying the pitch of the propeller, the best possible efficiency
can be realized throughout a range of airspeeds. To be efficient throughout the aircraft’s
envelope, the C-130 propeller is variable pitch.
To simplify the compressor aerodynamics of the gas generator, most turboprops, including the
T56, are designed to operate in flight at a constant RPM. To increase thrust, fuel is added to the
gas generator, and the increase in power is absorbed by increasing the blade angle of the
propeller.
Running the gas generator all the time at 100% in flight provides excellent go-around
performance, as the there is no spool-up time as is typical with a turbo-fan engine that must
accelerate turbo-machinary with a big rotational inertia. All that is required to increase thrust is
additional fuel to the gas generator and a small blade angle change. Since a large portion of the
wing is bathed in the propeller wash, not only does the thrust increase quickly, the addition of
power increases the lift coefficient at a constant angle of attack.
Ground and flight modes: For ground operations, a low pitch angle is required to minimize
thrust. Additionally, the ability to operate at negative blade angles provides reverse thrust and the
ability to back the aircraft on the ground without creating a FOD hazard. Too high a blade angle
makes it difficult to control taxi speed and creates a hazard during engine running on and off
loads. For flight operations, higher blade angles are required to ensure the engine propeller
combination is producing positive thrust. As a result of the different requirements for blade
angle on the ground and in-flight, the C-130 propeller control mechanism has two modes, an
“alpha” mode intended for flight or ground operation, and a “beta” mode intended only for
ground operation. On the C-130, the position of the throttle within the throttle quadrant
determines if the propeller is in alpha or beta mode.