B-24 post-factory mods

[Phil Irwin]

Found mention on a record card of "Mod Center Proj Dom 130 5/5" this was early 1943


As the aircraft was destined for anti-submarine work, I'm wondering if this was installation of radar?



Can anyone confirm please and does 5/5 mean 5 of 5 aircraft rather than 5th May !!



Many thanks

[edwest2]

In my view, this is a complicated subject involving many situations and various types of modifications.


Here is a partial introduction:


https://go.gale.com/ps/i.do?id=GALE%...non%7Ec16f044e


A more comprehensive overview:


"In every theater the normal depot work of repair and maintenance was supplemented by a growing load of modifications in the continuing race to keep equipment abreast of the demands of battle. By 1944 the air service organization in ETO was devoting the greater part of the resources of two huge base depots--employing all told some 28,000 men-to aircraft modification.† Production of standard models thus could be kept rolling with some assurance that their adaptation to particular requirements would be provided for in the theater.

"But this practice alone could not have sufficed. The number of modifications required--some small, some large--grew steadily. To relieve the pressure on the limited resources of the overseas air forces, it was desirable to incorporate the modifications as quickly as possible into the standard model produced by the manufacturer. Two factors, however, made this difficult. One was a consideration of time; major changes in a model, or even the incorporation of a good number of minor changes, could involve a serious delay in production with results affecting plans for the equipment of combat units. Moreover, requirements varied from theater to theater, so much so as to make it virtually impossible to introduce every needed modification into production models. The answer to these difficulties was found in the establishment of special modification centers in the United States.

"The original impetus to set up these modification centers came from General Brett who, during a visit to the United Kingdom in the summer and fall of 1941, learned that the British had found it necessary to undertake a good many modifications on American-built planes, with a resultant strain on their depot facilities. He accordingly recommended that every effort be made to incorporate the maximum number of modifications required by the British before the planes were shipped to England.12 This recommendation came at a time when there was already much concern over delays in production that were attributed to frequent changes of design,13 and special modification centers seemed in the circumstances to offer a logical solution.

"The Materiel Division proposed the establishment of ten modification centers,14 the first of which began operating at Cheyenne, Wyoming, late in January 1942. Originally, it was expected that the aircraft manufacturers would each operate the modification center for its own planes, but in this hope the AAF was destined to disappointment. Engulfed by the mounting demands for expanded production, the aircraft companies were in no position to take on the additional burden. Consequently, the AAF turned to the commercial airlines, whose maintenance shops contained the necessary facilities.15 The American, Chicago, Mid-Continent, Northwest, Southern, and United airlines were among the first to respond to the AAF's appeal. The B-25's used in the Doolittle raid on Tokyo in April 1942 had been modified for their special mission in February by the Mid-Continent Airlines at Minneapolis, one of the first companies to get a modification center into operation. By July 1942 twelve centers were in operation, and the grand total ultimately reached twenty-eight, though there were never this many in operation at any one time. To provide floor space and necessary facilities, the government ultimately spent $100,000,000 on twenty-one centers, eighteen of them operating exclusively for the modification of AAF-type planes. At the peak of operations, the floor space had reached 5,000,000 square feet and the employees totaled more than 45,000 persons.16

"Even so, demands for modification swelled to almost unmanageable proportions as the war progressed. In addition to the effort to keep up with the requirements of overseas air forces, the Navy, and foreign recipients, the modification centers also installed certain standardized items of equipment ordered by the Joint Aircraft Committee but not yet introduced into the production line; made changes found necessary for the safe and efficient operation of the plane; and attended to such maintenance work as might be necessary when the plane was delivered to the center. While getting the new centers into operation, the AAF leaned heavily on its own air service depots, which during the summer of 1942 were modifying planes at the rate of 500 per month; at the close of 1943 the Air Service Command found that modifications performed in its repair shops still represented 40 to 50 per cent of the work done. Attempts during that year to reduce the load by establishing two standardized sets of requirements for modification--one for planes assigned to European theaters and the other for aircraft scheduled for service against Japan--proved none too successful in the face of demands that continued to vary from theater to theater.17 Not until the summer of 1944, when production had reached a point offering assurance that established requirements would be met, was it possible to take the risk of delay in production schedules by making more modifications in the assembly line. In the preceding spring the responsibility of the Air Service Command for modifications had been limited to special projects, in the hope that a "single acceptance" policy--which is to say that modifications would be incorporated during production and before acceptance of the plane-might eventually be achieved.18

"The record makes it clear enough that the advantages of mass production in the aircraft program were gained only at the cost of a heavy burden of modification, and that at any time before 1944, that burden could have been substantially reduced only through unacceptable delays in production. Modifications ranged from the simplest to the most complex operations. The man-hours expended on a plane might vary from as few as a dozen to many hundred, with the heavy bombers requiring the fullest attention. The most common modifications involved the addition of armor and guns or communications and target-finding equipment, with the last changing very rapidly and becoming increasingly vital to operations. It might be necessary to alter the design and equipment of a B-24 for unanticipated service against submarines, or to modify another type for photo reconnaissance. Some planes required special protective devices against desert sands, others against the cold weather of arctic regions. Often the problem was to find room for more fuel, or for more bombs. With the B-29, which preempted much of the modification capacity during the latter half of the war, modification centers worked hard to take the "bugs" out of a plane that not only was hastily produced but in a very real sense had its service testing in combat.†The job usually was to add some new feature of design or equipment, or to make adjustments of existing equipment, but there were also instances in which devices incorporated in the standard model had to be removed before shipment to particular theaters. When hostilities ceased, only those modifications necessary for safety of operation or for experimental purposes were continued, and the responsibility for these fell now to normal agencies as the special centers were closed.19"


Source: https://www.ibiblio.org/hyperwar/AAF/VI/AAF-VI-10.html


Some modifications/additions were only temporary:


https://www.jstor.org/stable/26571085