Only one-third the number of workers are now needed to turn out over 33 percent more B-24 Liberator bomber fuselage nose sections at Consolidated Vultee Aircraft Corp's San Diego plants due to an apparently complicated, yet fundamentally simple, new production system.
Basically the new system is this: Build the nose section shells in stationary bucks as before, cut them into four sections, make all the necessary installations on moving assembly lines, then "button" them together again.
Achieving this apparently simple result, however, was far from easy; for assembly of the fuselage nose section literally the nerve center of the Liberator is a complicated business. It entails the use of almost 700,000 parts and rivets, plus installation of roughly 13,000 ft of wiring, 2,000 electrical and plumbing connections, and more than 2,000 ft of tubing. Into this stubby "brain" go all the controls needed by pilot, co-pilot, navigator, radio operator, and bombardier.
Under the original system, all these installations had to be made by crews of six workers no more could get into the nose section at the same time and work efficiently. That meant 6,000 man-hours per unit totaling 50 working days for a crew. To meet the new production schedules would have required a subassembly line three-quarters of a mile long for 200 fuselage noses would have to be in production at all times.
Under the new setup, the nose section shells running from the rear line of the bombardier's transparent enclosure to the front wing spar are assembled in their stationary bucks as before, with one exception. This involves leaving the rivets out along four cleavage lines, one on each side from front to back just below the pilot's window, and one on each side near the bottom.
With the nose section held together by bolts at each end of these cleavage lines, the shells are lifted from the bucks by overhead crane and placed on a portable cradle. A crew of four men then moves two special rolling jigs into place, one on each side. These are adjusted vertically by hand cranks so that pins which were bolted on the front, center, and rear of the side panels are fitted into sockets that have been bolted into place in the stationary bucks. Bolts which had held the shell together are then removed and the top panel, in turn broken into two segments, is placed in its own special rolling jig. A slight additional raising of the side panels breaks them loose from the bottom segment and flight deck. The sections, then ready to be cleaned up, proceed separately along their own primary assembly lines.
The lines have, of course, a varying number of stations to accommodate widely different numbers of installations. They are scheduled so the same segments that came out of stationary bucks are eventually remated.
In this connection it should be noted that leadmen are not used. Operations from breakdown to remating are in charge of foremen, with an assistant foreman for every five sections on the line. From remating to delivery to final assembly lines another foreman, with assistants, takes over.
The six sections are accommodated on four lines, one each for the side panels and flight deck with top and bottom panels and top decks alternating on the remaining line.
From breakdown to remating, the side panels proceed along parallel lines through eleven stations, including cleanup and inspection, although installations are in many cases different. In every case, however, the jobs to be done have been broken down into the smallest possible operation, both to give speed and to keep weights light, as the lines now employ some 35 percent women, with the figure constantly going higher.
Any station, though, may see installation of a wide variety of items, ranging from elevator and aileron control brackets, sub-installations involving a radio filter bracket, and de-icer control subassembly to soundproofing and heat insulation. The opposite panel, in this same station, may have comparatively simple operations, such as installation of part of the demand oxygen system, a gunner's portable oxygen bottle-holding bracket, and part of the automatic pilot elevator and aileron controls.
The job breakdown for each station has been designed both to put on installations next to the skin first and to permit the maximum number of workers to operate simultaneously without crowding, or without any one employee working directly above another.
Meanwhile, the flight deck section moves through 16 stations, with Stations 8 and 14 for inspection and numbers 15 and 16 as auxiliary cleanup stations. Some of the largest installations, such as nose wheel landing gear fittings and pilots' controls, are put in on the line. The pilots' controls, including throttle and mixture control column, elevator and aileron control wheels, rudder pedals, and all control cable leads, form a complete subassembly.
On this line one station is exclusively for hydraulic operations, where all tubing previously installed is connected.
At the same time, the top and bottom panels move along their own line through five stations, the last for cleanup and inspection. The two-segmented top panel, with comparatively few installations, is placed on its side. The fixture for the bottom panel, however, has a swiveling arrangement whereby the segment is swung on its side through the first two stations to facilitate cleanup riveting that which could not be easily done in the buck and to simplify initial installations.
Mating of the sections requires no special tooling. In fact the units are simply rolled from their assembly lines into an open floor area adjacent to air and electric power lines. The side panel fixtures are moved into position alongside the cradle holding the flight deck and, by hand crank adjustments, are raised or lowered into position and fastened temporarily with bolts. Then riveting teams go to work on both sides, "buttoning up" the three units. Next, the top sections are lifted from their fixtures by hand crane and lowered into place, and the riveting operation repeated. Finally, the bottom panel is rolled into position and riveted.
With the nose section again a single unit, it is transferred to a rolling dolly to take its place on the third mechanized assembly line. Here, moving sidewise to converse space, the nose goes through 30 stations. Since the majority of the installation work has been done in stations 5 to 16 preceding mating, these latter operations consist largely of
From the end of this line, the section goes to the special paint shop. It is then moved by special truck-trailer to the final assembly area where it is joined to center section and aft fuselage. Today, then, instead of a subassembly line three-quarters of a mile long, only a few hundred feet of factory space are required for fuselage nose assembly. Instead of 6,000 man-hours far less than 1,000 are now needed. By these and similar improvements in the handling of men and materials, Consolidated Vultee is keeping Liberator bombers rolling in ever increasing numbers off the production lines at both its San Diego and Fort Worth plants.
This article was originally published in the September, 1943, issue of Aviation magazine, vol 42, no 9, pp 161-164.
The original article includes 15 photos. Photos are not credited, but are certainly from Consolidated Vultee.