Design Analysis of
Consolidated B-24 Liberator

by J H Famme,
Chief Design Engineer, San Diego Div, Consolidated Vultee Aircraft Corp

Here's the detailed structural makeup behind the reputation of the Lib — famed "heavy," distinguished for its bomb load, speed, and range … The 13th of Aviation's comprehensive design series.

Since the long range, heavy bombardment airplane was an accepted type and the backbone of AAF flying equipment, it was logical that in 1939, when Consolidated was asked to design a four-engine bomber, the specifications called for greater bomb load capacity, greater speed and greater range. Our answer was the B-24 Liberator design.

The B-24 is in no way a radical departure from accepted design practice. Instead, it is a particularly successful combination of best features of a number of fundamentally sound airplanes which preceded it on the drawing boards and production lines of the company. It is a four engine, midwing monoplane with — until recently — a twin rudder tail assembly. This has now been replaced for the AAF by a single vertical fin-dorsal assembly — similar to that on the Navy Privateer PB4Y-2 which has been in production for over a year.

Although the Liberator was designed as a bomber, there have been more than 100 modifications and conversions — some 78 of which are in daily use. Other routine assignments include photographic, cargo, passenger, and route-exploration missions. Among its more recent modifications is a flying tanker conversion for ferrying gasoline. And all modifications were made possible by design and performance factors incorporated in the original specifications, basic details of which have not been altered.

The Liberator's modified Davis section wing design was chosen principally for the contribution it would make to greater range, through its long range cruising speed efficiency. The closed or four-sided modified elliptical fuselage, being actually a beam connecting wing and empennage, would be a deeper, stronger structure providing greatest space for bomb bays, crew quarters, armament, and operational equipment.

Fuselage

The fuselage is a semi-monocoque shell consisting of smooth skin reinforced with Z-type 24ST Alclad rolled stiffeners or stringers and transverse bulkheads and belt frames. The longitudinal stringers are generally spaced at about 6-in intervals, with greater concentrations where required for added strength. Longerons are used only to carry loads around openings at bomb bays, access doors, and other points where the skin-stringer combination is broken.

Belt frames, to maintain fuselage shape, are .040 24ST Alclad lipped channel, notched to pass over stringers and spaced about 1½ ft apart.

In the bomb bay, where belt frames and longitudinal stringers are interrupted, in the lower half of the fuselage, vertical stiffeners are spaced about 7 in apart to avoid passing stringers around or over bomb bay door tracks. Side longerons are channel shape, 5 in wide and 2 in deep at their widest part in the bomb bays, tapering out 6 to 8 ft in both ways.

Skin-stringer-bulkhead-belt-frame structural design was used because strength is dispersed rather than concentrated in a few critical members, a distinct advantage in any assembly subject to combat damage — bullet, shell, flak, and other enemy action.

By building the fuselage around the wing, juncture weight was saved through elimination of heavy fittings and bolts at the attachment points, and fuselage torsional stiffness was improved. This method joins the wing and fuselage by means of a continuous, riveted and bolted attachment around the periphery of the box structure of the wing formed by the upper and lower surfaces and the front and rear spars.

At the ends of the bomb bays are bulkheads connected longitudinally to a partial bulkhead in the center between the two bays by a beam which also forms the catwalk. Aft end bulkhead is a plate girder type built up of rolled sections and flat sheet. Upper part of the front bulkhead is a truss; the lower portion is flat sheet. The partial bulkhead between the two bays extends upward only to the wing to provide later support for the catwalk.

The catwalk through the bomb bays serves as a longeron and provides for transverse and longitudinal loads from the bomb racks. It consists of two U-shaped channels forming the sides, a corrugated Alclad top serving for the walk, and a smooth Alclad bottom forming part of the outside skin of the fuselage. Diaphragms of pressed sheet, spaced about 2 ft apart maintain the cross-section of the catwalk. The catwalk ends aft at a curved box beam which transmits loads to two longerons around the ball turret opening. These taper out 4 ft. beyond the turret opening. Forward, the catwalk tapers out ahead of the forward bomb bay. Around the nose wheel well, loads are passed through auxiliary longerons.

Nose wheel gear attaches at four points. Two upper attachments are to the floor truss of radio operator's compartment, the truss passing loads to the fuselage sides. Two lower attachments are to the main bulkhead of pilot's compartment, a plate girder built up of rolled sections and flat sheet, transmitting loads to the fuselage shell.

Vertical supports of the rear bomb racks are welded steel tube trusses in turn welded to gusset plates which are riveted to the rear spar of the wing, while forward racks tie to the lower surface of the wing by bolted fittings which pass loads to the wing internal structure. Bomb loads — because of this means of supporting the racks — are actually carried by the wing, rather than to the wing by means of the fuselage. For load purposes, the wing attaches to the fuselage through bolting and riveting of channel type bulkheads to the front and rear spars of the wing.

Bomb bay doors are flexible and made up of corrugated section, 24ST Alclad, spot-welded and riveted to an outer Alclad skin. To open, they slide up on the outside of the fuselage by means of the corrugations and running in curved tracks.

Bombardier's compartment is merely a continuation of the fuselage nose section. It is standard monocoque construction of flat sheet supported by stringers and three bulkheads built of formed U-channels of Alclad and 24ST sheet. Ahead of bombardier's position, the fuselage supports a tub-like structure in which the forward turret is mounted. Supporting structure is carried on two short and heavy deep beams of 24ST Alclad, bolted to the foremost fuselage station bulkhead by heavy aluminum alloy forgings.

Pilot's enclosure is approximately midway between front of fuselage and leading edge of wing, and is faired into main portion of the fuselage.

The flight deck, immediately aft of pilot's position, has a floor slightly lower than the pilot's floor. It carries drag loads from the main landing gear back to the wing and also supports radio equipment and radio operator.

Emergency exits are provided in the top of the fuselage above the bombardier and pilot positions, and in the bottom of the fuselage aft of the waist gun compartment for tail and waist gunners. Bombardier may also leave by way of the nose wheel door, and pilots and upper gunner may leave through the forward bomb bay. Waist and tail gunners can also use the waist gun windows.

Wing

Design of the B-24 wing was based on a geometrically similar airfoil used with considerable success on Consolidated Vultee Model 31 flying boat. Ease of production was one of the main considerations in selecting this wing design.

The wing envelope is established by connecting corresponding percentage ordinates of the construction root an construction tip sections. Construction tip and root sections are normal to a chord plane. Each left and right chord plane is set at an angle of 3° 26' to the horizontal, and the chord section on the plane of symmetry is established by intersections of the percentage point connecting lines. The tip is faired from the construction envelope in conventional manner.

A center section and two outer panels comprise the main units of the wing and are mated by flush, tension-bolted splices. The spar locations were widely spaced to provide maximum room for fuel cells of sufficient capacity to insure the greater range specified by the AAF, and also to provide clearance for main landing gear wheels.

The center section has a span of 55 ft, and its structure includes two auxiliary spars of plate girder type, built up of heavy, rolled angles and flat sheet riveted to two of the main wing bulkheads to support the landing gear. Both main and auxiliary spars are Wagner type with Z-section vertical stiffeners spaced 4-6 in apart, and rolled angle flanges. To eliminate joggles, the flanges are placed back-to-back on the web against the face of the paired angles. Stiffeners are placed on the web surface opposite the flanges, so so that the components can be easily fitted together without appreciable loss of structural efficiency.

Bending loads are carried primarily by the upper and lower surface plate-stringer combinations. There are 5 upper surface skin sections or panels on each side of the centerline. The upper skin at the root is .125 24ST Alclad for the forward 60 percent of the interspar distance, and .091 24ST Alclad for the aft 40 percent of the interspar distance. These skins extend spanwise 146 in — to the end of the main fuel cell region. The remaining skins on the upper surface of the center section are divided into 3 strips. The forward strip is .114, the center strip .102, and the aft strip is .091 24ST Alclad. The gage reductions are made to save weight when strength requirements are reduced.

Rolled hat-section stringers of approximately similar gages are used for skin stiffening. Skin and hat splices occur at the bulkheads 147 in from the centerline, and also at the centerline. Forged flanged strap fittings and splice plates connect both hat sections and skins. Outboard splice plates are buried, causing the splices to be flush. At the outer panel-to-center section splice the hat sections are connected to an inverted flange angle by U-forgings riveted to the sides of the hats.

The lower surface plating of the center panel is stiffened by 1&frac; in drawn Z-sections. The plating and stringers are tapered from even distribution at the splice to bands approximately 10 in wide at the front and rear spars adjacent to the wheel well. The bands are parallel to the main spars, and the plating becomes continuous a the outboard end of the fuel tank. Material is concentrated by reinforcing sheets which reach a maximum thickness of approximately 9/16 in at the wheel well. Spar flanges are joggled to accept the reinforcing sheets, and Z-stringers are spliced by fittings similar to those used for the hats at the main tank bulkheads. Stringers are attached to the wing splice attaching angles by forged T-fittings. Rivets on the upper surface of the interspar area are machine countersunk. When the required diameter is 3/16 in or less, brazier-head rivets are used on the lower surface: all larger rivers are machine countersunk.

Center section interspar bulkheads are of three types — Wagner beam, truss, and pressed sheet — depending on what loads they carry, type of load, and whether access through them is required. There are 27 of them, 13 on each side and one at the center. The Wagner beam web is flat Alclad sheet and rolled angle flanges set back-to-back with the web on one side and stiffeners on the other. Trusses are Warren type with rolled channel chord members and interconnecting diagonal rolled channels.

Main wing fittings include two hoist fittings which may be used in lifting the entire airplane in the weight-empty condition. They are attached to the bulkhead at the wing centerline.

Landing gear fittings are simple forged flanged bosses, riveted to the auxiliary spars, also Wagner type with a web of flat Alclad sheet and rolled angle flanges set back-to-back, the web on one side and stiffeners on the other.

Upper engine mounting fitting forgings are bolted and riveted directly to the upper surface of the front spar, while lower engine mount fittings are carried on a welded tubular sub-structure.

Fuel Tanks

Two integral fuel tanks, each extending 147 in from the wing centerline, were installed in the first Liberator wing. Sealing was accomplished by placing 1/32 in synthetic rubber gaskets in the tank seams. Little trouble was experienced with this type of construction, which had been previously developed and proved in the PBY's but military requirements made it necessary to replace the integral fuel tanks with self-sealing cells. Later, auxiliary cells were added in the area outboard from the wheel wells to the first outer panel bulkhead, providing still greater range.

No basic design change was required to effect the fuel tank changes. A larger access door on the underside, removable members in two bulkheads adjacent to the ends of the tank region, and small access doors through which to reach fuel cell manifolds were provided and constituted the only wing changes required. Space for the additional tanks existed in the original wing and was merely utilized.

There are 18 self-sealing fuel cells installed in the wing, 9 on each side of the centerline. The 12 inboard cells make up the main fuel cell system, with a capacity of 2,343 gal, and 6 outboard cells comprise the two auxiliary systems with a capacity of 450 gal, giving a wing tank capacity of 2,793 gal. Two additional cells with a combined capacity of 790 gal can be installed in the forward bomb bay.

The 18 cells comprising the normal or wing system are interconnected by flexible self-sealing manifolds to make six units of three cells each. Main system manifold connections are accessible through access doors in the lower surface of the wing. Auxiliary system manifold connections are reached from the inboard side of inboard nacelles. Main system units of three cells with interconnecting manifolds have a fuel booster pump located under the final cell of the unit, a shut-off selector valve, fuel strainer, and engine-driven pump.

Normally, fuel from one main unit is delivered independently to one engine (engine No 1 from system No 1). Fuel is transferred from the auxiliary to the main cells by the fuel transfer system. Connection of the auxiliary cells to the engines is through the crossfeed system.

Main fuel cells in the wing center section are held in place by their fit to the compartment. Where the cell does not completely occupy the full fore and aft depth, spacers are installed between the cell and front spar. Canvas curtains snap into place between the sides of the cells and the rib members.

The center section compartment is provided with a drain on each side of the centerline to discharge overboard any fuel which may leak from the cells. Flanges of these drains are located immediately aft of the two inboard booster pumps and are fitted with shut-off valves and overboard discharge lines.

The booster pump gland drains empty into these lines. The drain outlets lead through a bulkhead on each side of the catwalk and extend below the skin. The wing compartment vent lines are located on each side of the centerline of the inboard nacelles and pass through the center of the wing spar and out through the wing lower surface aft of the No 2 and No 3 nacelles.

Anti-icing System

Leading edges of airfoils were originally designed for boot-type de-icers, but all current models of the airplane feature Convair's new exhaust-heat anti-icing system. This has made it necessary to provide ducts and double skins for conducting heated air to the leading edge surfaces. Edge strips, screwed to a ledge at the spar flange, make it possible to attach the leading edges by means of self-locking nuts in gang channels.

Air heated by exhaust gases is piped through the leading edge and the other parts of the plane — pilot's, radio operator's, tail gunner's, and bombardier's compartments, and the upper turret position. Other crew positions rely on electrically heated clothing for protection.

The system consists of a heat exchanger in the exhaust stack just ahead of the turbosupercharger, four in all,through which outside air is passed before flowing through ducts to the wing, empennage, and fuselage compartments. Ducting is aluminum sheet tubing covered with sheet asbestos, and averages 5 in in diameter.

Each outer panel of the wing comprises an interspar structure with a removable leading edge and wing tip, a trailing edge structure forward of the ailerons, and a trailing edge structure forward of and over the flap. The spars are at 10 and 66.2 percent of the chord, and their design is similar to that of the center section spars. Interspar ribs are pressed aluminum alloy, and plate-stringer combinations complete the bending box.

The upper surface employs hat sections at the inboard end, and these splice int 1½ in Z-stringers which in turn splice down to 1 in stringers and terminate at the base of the wing tip. The lower surface plates-stringer combination is similar, except for the fact that hat sections are not used, 1½ and 1 in Zs being used for stiffeners. During assembly operations, the wing skins are applied to the upper surface first, front and rear strips are then attached to the lower surface, and the closure is competed by attaching a center strip provided with hand holes. New assembly procedures make it possible to attach plate-stringer surfaces as units.

The ailerons are of typical torque-box pressed-rib construction, fabric-covered. A two-horn gear box control system was originally used in connection with these surfaces, but this was discontinued in favor of a single-horn push-pull-tube bellcrank system. Trimming tabs are provided on both ailerons of latest Liberators.

Most of the rolled sections in the B-24 wing are stretched approximately 3½ percent to the RT condition; and, since few extrusions are used, Convair has been able to control section output simply by using sheet stock. Although rolled sections are not as dimensionally accurate as extrusions, little trouble has been experienced in constructing the wings because of flexibility of the fundamental design.

The Fowler flaps have an area of approximately 144 sq ft, and a movement downward of 40°. The individual flap is supported by roller carriages, which engage five tracks, four of which are attached to the center section and the fifth attached to the outer panel. Tracks are steel I-beams bolted to a tubular planar truss. Clevises at the forward ends of the tubular truss attach to lugs which protrude through the spar at the spar flanges and attach to bulkhead chord members. Flap controls comprise a cable system actuated by a hydraulic cylinder energized by pressure from the main hydraulic system.

Engine mounts attach to the front spar of the inner section of the wing. Mounts are of welded 4130 c-m steel tubing. They are of two-bay type, 45-3/8 in long. Attachment is at four points, by tension bolts, upper two being to the spar and lower two to after-mounts which project downward from the lower surface of the wing, because of the thin wing design.

Space in the forward bay, behind the steel firewall, is occupied by an oil tank, and the oil cooler, on the right side, and intercooler on the left side. Aft bay provides space for a turbosupercharger and its regulator.

The entire assembly — mount, engine, cowling, and accessories — is assembled as a removable unit, which while standardized, is not interchangeable in other than the intended location.

Each engine of the Liberator has its own complete independent oil system consisting of a self-sealing reservoir of 42 gal capacity located within and attached by brackets to the engine mount; a temperature regulator located behind the engine and within the mount; a temperature regulator located behind the engine and within the mount; an oil dilution system; and drains, piping, controls, and oil separator.

Power plants are Model C-4, P & W, 1,200 hp, each attached by eight flexible shock mounts. Engines Nos 1 and 2 drive the instrument system vacuum pumps and No 3 drives the main hydraulic system hydro-pressure pump.

Each power plant is enclosed from the nose ring to the wing by Alclad cowling, except around the exhaust system, where stainless steel is used.

The horizontal tail surfaces of the original design (twin rudder assembly) have NACA section No 0015 and contain 192 sq ft. Span is 26 ft and maximum chord 7 ft 8-3/16 in. Distance from the design gross weight CG, assumed at 25 percent MAC, to the one-third maximum chord point is 33.40 ft, which is approximately 3&frac; times MAC. Stabilizer area, including elevator balance, is 140.5 sq ft. Its normal setting relative to the longitudinal axis is 2.5°.

The elevator has an area of 67.1 sq ft with 51.5 sq ft aft of the hinge line. Angular movement is 30° up and 20° down. the elevator is aerodynamically balanced and all spanwise elements are statically balanced about the hinge line. Tabs in the trailing edge have an area of 4.95 sq ft and are controlled by an irreversible mechanism.

Vertical tail surfaces have NACA section No 0007 with a fin area of 123 sq ft and rudder area of 48.8 sq ft. Rudders are aerodynamically balanced and fully balanced statically. Spanwise elements are statically balanced about the hinge line. Tabs have a total area of 3.1 sq ft, and are equipped with irreversible controls. Rudder angular movement is 10° right and left of center.

The new, single tail assembly, designed at the request of the AAF, required few changes in the original aft fuselage structures. The new stabilizer is designed to fit the old type fittings, with the dorsal and fin attaching to new structure. Front fin spar attaches to a new, built-up bulkhead.

All tail assembly control surfaces are of aluminum torque box and rib construction, covered with fabric. The stabilizer, constructed as a separate assembly, has a smooth sheet metal skin and is attached to the fuselage with only four fittings, to facilitate replacement. The entire tail assembly is mounted just enough forward of the tail gunner's compartment so that the trailing edge does not obscure the gunner's vision.

Propellers are Hamilton Standard Hydromatic three-bladed constant speed type, with quick feathering feature. Clearances are 37 in to ground and 23&frac; in to fuselage. Normal distance to the plane of each propeller disk is 74-1/6 in at the centerline of the inboard engine. Controls are electrical and convenient to both pilot and co-pilot. Feathering pump oil is obtained from the main oil tank.

Propeller anti-icing is achieved with two electrically driven pumps installed below a 21-gal tank located above the wing center section, between the life raft doors. One pump supplies pressure for both inboard propeller anti-icing rings and the other for the outboard propellers.

Anti-icing systems for pilots' and bombardier's windshield exteriors are connected directly to the same tank. De-icing and defrosting of window interiors are by heat exchangers and flexible defroster tubing adjustable for direction against windows.

Landing gear of the B-24 is tricycle type with fore and aft wheel base of 16 ft and a main gear width of 26 ft 7&frac; in. In addition to the main gear and nose wheel, a retractable skid is provided, which, while not strong enough for full tail landing loads, will withstanding the load of rocking after landing. It is supported by an Alclad sheet box structure built into the lower aft end of the fuselage, below the aft gun position, and is extended and retracted hydraulically.

Main gear wheels are Air Corps Type 111, made of aluminum alloy or magnesium alloy castings, requiring 56 in x 16-ply tires. Nose wheel is fitted with 36 in x 10-ply tire.

Hydro-pneumatic struts are used on the main and nose gears, with main gear retracting outward and upward into wells in the undersurface of the center wings, and the nose wheel retracting upward and slightly aft into a well just forward of pilot's cockpit floor. The nose wheel is held in the up position by a latch, and the door closing the opening is actuated by the gear mechanism.

Main gear assembly is supported from two false or auxiliary spars located just outboard of the inboard engine cowling, between the front and rear spars. They are plate girder type of heavy rolled angles and flat sheet riveted to two of the main wing bulkheads. Both gears are equipped with emergency release and retraction mechanisms. Brakes are duplex expander tube type.

Being primarily a bombardment airplane, the B-24, however, was required to have armament for defensive as well as offensive action. For offensive action, it can carry 4 to 22 bombs in its two bays, and additional bombs in external racks attached to the under surface of the inboard wings.

Latest versions of the Liberator carry an average of ten .50-cal guns aimed and fired from side openings in pairs in 4 power-operated turrets situated in the nose, the top, belly and tail. Remaining 2 guns are flexibly mounted, so that they can be manually aimed and fired from side waist enclosure in aft part of fuselage. Armor plate protects areas around all crew members and vital equipment.

Main hydraulic system of the Liberator operates the wing flaps, bomb bay doors, wheel brakes, and landing gear. Rear gunner's turret is hydraulically powered by a separate system mounted on the right side of the fuselage adjacent to the tail turret. The system is a combination of the better features of the direct pressure and open center systems, and is termed an open center pressure and return unit.

The B-24 electrical system has three main sources of energy — batteries, generators, and a 2 kw auxiliary power unit located on the left side of the fuselage just ahead of the bomb bay and below the flight deck. The units connect to a common distribution system which covers the entire plane. The DC-to-AC inverters supply energy to special equipment requiring alternating current.

Radio, interphone, and directional radio equipment aboard the B-24 derive power from the 24 VDC supply of the main power system. The interphone consists of an amplifier, dynamotor, jack box, and one throat microphone and microphone-amplifying equipment for each crew station. Each throat microphone is equipped with switch cord or a push-to-talk switch.

The command radio consisting of two transmitters and three receivers, is mounted above the wing center section just aft of the life rafts. Modulator unit, dynamotor modulator unit, and dynamotor are mounted aft of the compass receiver, on the rack for the radar equipment. Liaison radio includes one transmitter located on the flight deck, under the radio operator's table, and a receiver on the table. Radio compass is located over the wing center section on the right side, and the marker beacon is located in the bomb bay.

Capacity of the oxygen system, originally provided by 5 fixed-position bottles in the upper aft section of outboard engine mounts, has been increased to 26 bottles of 350-psi type, located at strategic points. Pressure scale, translated in terms of altitude is controlled by the user and maintained at a setting 5,000 ft higher than the indicated altitude.

Although, like other US combat aircraft, the B-24 Liberator has frequently been subject to increases in empty weight because of need for additional equipment and protection dictated by the ever-shifting exigencies of war, it has continued to deliver larger bomb loads, farther and faster. That was its designed intent.

This article was originally published in the July, 1945, issue of Aviation magazine, vol 44, no 7, pp 121-143.
A PDF of this article includes 22 photos, 10 diagrams, a three-view, and 10 detail drawings.
Note that the PDF is recovered from microfilm, rather than having been scanned from magazine originals, so the quality is not as good as it might be.

Photo and drawing captions:

Data Tables









Liberator Wing Data
Airfoil section designation:
    RootCVAC 22%
    TipCVAC 9.3%
Wing area1,048 sq ft
Span110'
Root chord14'
Tip chord5' 2-13/32"
Thickness at root22%
Thickness at tip9.3%
Incidence
Dihedral on upper 30% chord line1° 30'
Sweepback (LE)3° 30'
Trailing edge sweep forward5° 38'
Twistnone
Spar location, front10% chord
Spar location, rear66.2% chord
Aspect ratio11.55
Mean aerodynamic chord, length123.72"
  Location relative to LE
    LW (chord — horizontal)17.04" aft
    Root chord — vertical16.6" above
Fuselage Dimensions
Length66' 4"
Maximum height10' 5"
Maximum width7' 5"
Flap Data
TypeFowler
Area, total144.4 sq ft
Movement0° to 40° down
Aileron Data
Area (aft of hinge)64.4 sq ft
Angular movement20° up, 20° down
Differential motionnone
Distance from plane of symmetry
  to centroid of aileron area
40' (approx)
BalanceAerodynamic
Tab area3.64 sq ft
Angular tab movement±10°
Tail Group
Horizontal Tail Surfaces:
  SectionNACA 0015
  Area192 sq ft
  Span26'
  Maximum chord7' 8-3/16"
  Distance from design gross weight CG
    (assumed at 25% MAC
    (to 1/3 maximum chord point)
33.40'
approx 3½ × MAC
Stabilizer:
  Area, including elevator balance140.5 sq ft
  Normal setting
    (relative to longitudinal axis)
2.5°
  Angular movementfixed
Elevator:
  Area, total67.1 sq ft
  Area aft of hinge line51.5 sq ft
  Angular movement30° up, 20° down
  BalanceAerodynamic
  Tab area4.95 sq ft
  Tab angular movement±10°
Vertical Tail Surfaces:
  SectionNACA 0007
Fin:
  Area, total123 sq ft
  Normal setting
  Angular movementfixed
Rudder:
  Area, aft of hinge48.8 sq ft
  Angular movement20° R, 20° L
  BalanceAerodynamic
  Dynamic balance coefficient0.014 (no greater)
  Tab area3.1 sq ft
  Tab angular movement10° R, 10° L
Design Weights
lb    
Wing Group
  Center section4,715
  Outer panel1,178
  Tips39
  Ailerons157
  Flaps252
    Total6,575
Tail Group
  Stabilizer360
  Elevator136
  Fin216
  Rudder91
    Total830
Fuselage3,334
Landing Gear
  Main2,562
  Nose354
  Bumper (wheel or skid)28
  Selector valve3
    Total2,947
Engine Nacelle Group1,539
Power Plant Group
  Engine (as installed)6,032
  Engine accessories1,626
  Power plant controls336
  Propellers (4)1,804
  Starting system212
    Total13,243
Lubricating System
  Tanks and protection380
  Piping, etc325
    Total705
Fuel System
  Tanks and protection2,248
  Piping, etc280
    Total2,528
Fixed Equipment Group
  Instruments141
  Surface controls630
  Hydraulic system455
  Electrical1,038
  Communicating585
  Armament provisions3,654
  Furnishings:
    Personnel accommodations163
    Emergency acccommodations65
    Provisions for flight707
    Air conditioning112
  Anti-icing460
  Auxiliary power unit123
    Total8,131
Standard Weight Empty36,562
Performance at 56,000 lb Gross Weight
High speed, 25,000 ft
  military power
over 294 mph
Operating speed, 25,000 ftover 230 mph
Tactical radius of action,
  normal mission
750 mi
Service ceiling32,000 ft
Takeoff run to clear 50'under 3,950 ft
Stalling speed79 mph
Balance Factors
Alternate gross weight CG location
  with wheels up
  aft of leading edge
30.9% MAC
Most forward for adequate control,
  landing power off
23% MAC
Most aft for satisfactory longitudinal
  stability with power and for
  satisfactory ground handling
34%
Useful Load
lb    
Crew (nine men)2,000
Engine fuel (2,120 gal)12,718
Engine oil (128 gal)960
Guns and accessories1,953
Bombs2,007
Total useful loadover 19,438
Weight emptyover 36,652
Gross weightover 56,000