Combat reports from the field revealed that the B-24D Liberator was insufficiently well protected against attacks from the front, and various field modifications were carried out to beef up the forward armament. One modification that did work fairly well was the field installation of a Consolidated A-6 tail turret in the NOSE of a B-24D. The idea was supposedly the brainchild of Art Rogers, who first thought of it in April of 1942. A mockup was tried out at Ford/Willow Run in August of 1942. It took a while, however, before a working turret was actually installed in the nose of a Liberator. The first nose turrent was installed in 41-23759. It made its first flight in November of 1942.
So successful was this modification was that the Army authorized the installation of nose turrets in all Pacific-bound Liberators. B-24Ds modified with nose turrets were designated B-24D1. The first such modifications were performed by the Hawaii Air Depot, with several stateside Air Depots also joining the program. The stateside-modified Liberators had a redesigned bombardier station which gave the aircraft nose a pronounced drooped chin and a distinct "tacked-on" appearance.
Based on the success of the installations of Consolidated A6 tail turrets in the noses of B-24D1s, the USAAF sought to have nose turrets fitted as standard factory-installed equipment on production Liberators. The USAAF assigned the designation B-24H to the initial version of the Liberator to be fitted with nose turrets on the production line. Ford/Willow Run was to be the primary manufacturer of the B-24H, with Douglas/Tulsa and Consolidated/Fort Worth being supplied with Ford-built components for final assembly.
Emerson Electric was instructed to modify their developmental tail turret for use in the Liberator's nose. Emerson engineers worked in collaboration with Consolidated engineers to adapt the A-15 turret to the B-24 airframe. Drawings of the Emerson turret were shipped to Ford/Willow Run, where a wooden mockup was hastily built to help in adapting the production line for the nose turret. The Emerson A-15 electrically-operated turret that finally emerged had a distinctive smooth, cylindrical appearance, as opposed to the beveled look of the Consolidated A-6 hydraulically-operated turret that had been installed in the nose of the modified B-24D1s. The nose turret fairing design that had to be used to adapt the nose to the turret introduced the "S"-shaped paneling that was to characterize all future Ford-built B-24 assemblies.
All B-24Hs (including those assembled intermittently with the B-24J at Fort Worth) were fitted at the factory with these Emerson nose turrets. Other Convair/Fort Worth Liberators were delivered with Consolidated A-6 nose turrets as B-24J until the spring of 1944, at which time the Fort Worth-built B-24J adopted the Emerson turret as standard.
Because of the many structural changes required to accommodate the nose turret, the first B-24Hs were delivered slightly behind schedule, with the first machines rolling off the production lines at Ford in late June of 1943. B-24H sub-assemblies were shipped by Ford to both Consolidated/Fort Worth and Douglas/Tulsa for final assembly. Fully-assembled B-24Hs began to come off the assembly lines at Consolidated/Fort Worth and Douglas/Tulsa in August of 1943.
56 major changes were needed in the basic B-24D airframe to make it compatible with a nose turret. The bombardier station had to be completely redesigned, and the nose gear doors were changed from inward-opening to outward-opening, and the outward-opening doors were retained throughout the entire B-24H production run. The added weight in the nose caused a change in the location of the center of gravity, but this was not a problem since the Liberator had previously been somewhat tail heavy. Consequently, the addition of the nose turret actually improved the handling of the Liberator.
The B-24H also had an improved Consolidated A-6B tail turret that featured considerably larger transparent areas on each side which improved the tail gunner's visibility. On Block 20 and subsequent B-24Hs, the gunner positions were enclosed behind permanent windows, with the guns being fired through K-6 swivel mounts cut into the lower corners of these windows. This resulted in reduced weight and increased crew comfort, since the waist gunners no longer had to be subjected to a hurricane of frigid wind whenever they stationed at their guns. In addition, the two waist gun mounts were staggered, lessening the changes that the two gunners would interfere with each other during combat. However, the waist gunner windows themselves were not staggered, as they were in the later B-17G
It was not until the B-24J-5-FO or -10-FO production blocks that the waist gun mounts were in the lower corner of the plexiglass enclosures. During the H production run, the mounts were through the fuselage skin, but there were exceptions due to post-production replacements.
The B-24H was initially fitted with the Martin A-3C top turret, the same unit that was installed in the B-24D. Fairly late in the H-series (probably in and around production block 30), the Martin A-3C top turret was replaced by a new and revised Martin A-3D turret with an enlarged and higher plexiglas cover which improved the visibility. Also, the tunnel gun scanning windows on the lower sides of the rear fuselage were deleted on a number of late-series B-24H aircraft.
The R-1830-43 engine was initially used on B-24H production lots from all three companies. The Douglas-built B-24Hs retained the -43 engines throughout the entire production run, but the other two companies switched to the R-1830-65 engine with the B-24H-5 production block at both plants. The only difference between the two types of engines was the type of carburetor and magnetos that were installed. The -43 engine had a Bendix carburetor whereas the -65 engine had the CECO carburetor. The -43 engine was built by Pratt & Whitney, the -43A was built by Buick and Chevrolet, the -65 was built by Buick and the -65A was built by Buick and Chevrolet.
The camouflage paint scheme was deleted at about two-thirds through the B-24H production run, and subsequent Liberators were delivered in a natural metal finish. This occurred first at the Douglas plant at about mid block 10, then later at block 20 at both Willow Run and at the Fort Worth assembly-line.
By March of 1944, Ford was rolling a new B-24H off the production line every 100 minutes. Production for the B-24H was 1780 at Ford/Willow Run, 738 at Consolidated/Fort Worth, and 582 at Douglas/Tulsa, for a total of 3100. The last B-24H was built in May of 1944 at Consolidated/Fort Worth. By that date, all five plants in the Liberator Production Pool had switched over to the manufacture of the Emerson-equipped B-24J version.
41-28574/28639 Douglas-Tulsa B-24H-1-DT Liberator 41-28640/28668 Douglas-Tulsa B-24H-5-DT Liberator 41-28669/28752 Douglas-Tulsa B-24H-10-DT Liberator 41-28753/28941 Douglas-Tulsa B-24H-15-DT Liberator 41-28942/29006 Douglas-Tulsa B-24H-20-DT Liberator 41-29116/29187 Consolidated B-24H-1-CF Liberator 41-29188/29258 Consolidated B-24H-5-CF Liberator 41-29259/29335 Consolidated B-24H-10-CF Liberator 41-29336/29606 Consolidated B-24H-15-CF Liberator 41-29607/29608 Consolidated B-24H-20-CF Liberator 42-7465/7717 Ford B-24H-1-FO Liberator 42-7718/7769 Ford B-24H-5-FO Liberator 42-50277/50354 Consolidated B-24H-20-CF Liberator 42-50355/50410 Consolidated B-24H-25-CF Liberator 42-50411/50451 Consolidated B-24H-30-CF Liberator 42-51077/51103 Douglas-Tulsa B-24H-20-DT Liberator 42-51104/51181 Douglas-Tulsa B-24H-25-DT Liberator 42-51182/51225 Douglas-Tulsa B-24H-30-DT Liberator 42-52077/52113 Ford B-24H-5-FO Liberator 42-52114/52302 Ford B-24H-10-FO Liberator 42-52303/52776 Ford B-24H-15-FO Liberator 42-64432/64440 Consolidated B-24H-1-CF Liberator 42-64441/64451 Consolidated B-24H-5-CF Liberator 42-64452/64501 Consolidated B-24H-10-CF Liberator 42-94729/94794 Ford B-24H-15-FO Liberator 42-94795/95022 Ford B-24H-20-FO Liberator 42-95023/95288 Ford B-24H-25-FO Liberator 42-95289/95503 Ford B-24H-30-FO Liberator