Hybrid Aircraft - Boeing B-17G / Consolidated B-24J

The availability of the Consolidated B-24 in increasing numbers soon made it evident that, whatever the qualities of its companion, the B-17, the Liberator led in several vital areas, especially in range and bomb load. But by 1944, an additional turret in the nose had increased weight and drag reduced the margin. In addition, the Liberator's ceiling, already less than the B-17s, was further reduced. Furthermore, the addition of the turred reduced forward vision from the flight deck, and cramped the working areas of the naviagtor and bombardier, in the nose.

The deterioration of the B-24's operational suitability concerned the USAAF sufficiently for them to launch a priority project to improve the Liberator's performance. Air Materiel Command undertook the "B-24 Weight Reduction Program", with the objectives of improving the speed and altitude capabilities of the aircraft, and also of solving the poor forward visibility and crew quarters problems.

In March 1944, at Wright Field, the Weight Reduction Committee considered a range of options. Among these were more powerful turbo superchargers to improve the ceiling, a faired Bell power boost tail turret, and a single tail assembly calculated to add 10 mph (16 km/h) to the B-24's speed.

The B-17 nose configuration was better streamlined, and provided adequate working space for the navigator and excellent visibility for the bombardier. It was at first used as a bench-mark by which to measure any B-24 modification. Eventually, the suggestion was made to actually put a Fortress nose onto a Liberator airframe.

On May 25th, 1944, Air Materiel Command assigned the experiment a First Priority Project rating. A preliminary study at Wright Field reported that a completely new nose design would be more practical, but conceded that fitting a B-17 nose was feasible. The actual conversion was scheduled to begin in June, at Air Service Command's Middletown, Ohio, facilities.

It was agreed that the project should be finished 20 days after receiving a new B-17G nose section from the Douglas plant at Long Beach, California. The airframe was to be B-24J serial 42-73130, made available by Aircraft Test Control and flown to Middletown on June 5th. The aircraft was weighed, and work began on removing the nose and making a mock-up mating structure.

As the project looked for ways to shorten their 20-day time-frame, they found that an accident at Langley Field, Virginia, had considerably damaged B-17G serial 42-97772, but the nose section was still fairly intact. It was requisitioned and reached Middletown on June 11th. The nose section from California arrived five days later and was used to replace damaged parts on the section from Langley.

Now began a complex mating of the two major components. Not only were these of quite different cross sections, but installed equipment did not match up. Side structural fairings were formed by a continuation rearwards of the side components of the B-17 nose section, to end at a point on the B-24 fuselage just forward of the bomb bay doors. The reverse happened on the upper fuselage, where the B-24 was faired forwards onto the B-17 nose.

The modification was completed on July 2nd. Whilst not over-attractive, the new nose did at least appear to be an aerodynamic improvement. One problem was that the new nose not only added about two feet to the overall length of the aircraft, but it also increased its weight by 437 lb. (198 kg.).

The aircraft was sent to Wright Field for a brief check-out flight on July 6th by the Flight Section of Materiel Command. With a gross takeoff weight of 56,000 lb. (25400 kg) and after speed, power and stability tests at 10,000 ft. (3048 m) the test crew concluded the aircraft performance was "essentially the same as other B-24 airplanes", but with an airspeed "apparently 8.5 mph (13.7 km/h) faster". The aircraft was sent to the AAF Proving Ground at Eglin Field, Florida, via Bolling Field, Washington, DC, for the edification of Pentagon representatives.

Three flights were scheduled. The first, at low altitude, was for familiarisation and instrument calibration. The next two would be identical except that, on the third, the aircraft would carry the weight of a fully-loaded B-24J.

The missions were flown during August. On both altitude flights, the aircraft was only able to reach a ceiling of 18,500-19,000 ft. (5638-5791 m.), about 2/3 that of an ordinary B-24. At that point cylinder head temperatures soared and the cowl flaps had to be opened, adding to drag, preventing any further climbing, and producing a mild tail buffeting.

The Eglin report condemned the modified aircraft as "operationally unsuitable". They pointed to weight increase, stability problems, the poor ceiling and generally poor performance, and recommended the project be discontinued.

Finally the Engineering Division of Air Materiel Command admitted that it would be better simply to redesign the B-24J nose. Most of the added weight was due to ammunition for the B-17 nose and cheek guns, almost a third of a ton. This weight did offset the aerodynamics problems of the forward-stretching nose somewhat, which apparently would otherwise have been worse.

There was some dispute that the head temperatures which prevented climbing to a higher ceiling could be blamed on the B-17 nose. They had allegedly been reported in other B-24Js. The test crews agreed that the crew space in the nose had been vastly improved.