Long-range carrier-based escort fighters from southern California that never were

The earliest years of the Cold War in the late 1940s saw a proliferation of requirements by the US Navy's Bureau of Aeronautics for different types of carrier-based fighter planes, namely day fighters, all-weather fighters, and interceptors, which produced the F9F, F3D, F3H, and F4D. However, mostly lost in talk with respect to US Navy jet fighter development in the 1946-1950 period is the fact that while the US Air Force tinkered with a penetration fighter requirement that led to the XF-88, XF-90, and YF-93, the BuAer had its own requirement for a long-range escort fighter, and although a number of companies from the Los Angeles area came up with extraordinary designs for such an aircraft, the Navy's long-range escort fighter specification of the late 1940s ended up being dropped before any design submission could be selected for full-scale development.

On December 30, 1947, the Navy's Bureau of Aeronautics issued the OS-112 requirement for a four-seat jet fighter with a top speed of 535 mph (861 km/h) at 40,000 ft (12,192 meters), a operational combat radius of 1,381 miles (2,224 km), a service ceiling of 45,000 ft (13,716 meters), and a climb rate of 5,000 ft/min (25.4 m/s). Although the USSR did not yet have a nuclear weapon and was seen by US intelligence as a long way off from testing one, the appearance of the Soviet Union's MiG-15 meant that the Navy may have felt it necessary to plan for operating an escort fighter to provide protection of the forthcoming North American AJ Savage strategic nuclear-armed bomber if that aircraft conducted nuclear strike missions deep inside the Soviet heartland from the high seas. A July 1948 deadline for companies to submit bids for the OS-112 spelled out of the Navy, and six companies worked out designs for a carrier-based escort fighter: Boeing, Curtiss-Wright, Douglas, Lockheed, McDonnell, and Vought.

Three view drawing of the Douglas Model 1163 naval escort fighter (dated July 30, 1948)

The Douglas company was well-positioned to undertake design studies for an escort fighter to fulfill the parameters of the OS-112 requirement buoyed by its experience with design and development of the F3D Skyknight all-weather fighter. The Santa Monica and El Segundo branches of Douglas worked out two independent naval escort fighter studies, with the Santa Monica division's proposal bearing the company designation Model 1163 and the El Segundo branch's design being called D-585. The Model 1163, conceived in July 1948, was a very large escort fighter design which measured 65 feet 3.5 in (19.90 meters) long and had wings with a moderately swept leading edge and straight trailing edge spanning 90 feet (27.43 meters) when unfolded and 35 feet (10.67 meters) when folded. It was powered by three 4,200 lb (18.7 kN) thrust Westinghouse J46 turbojets mounted below the fuselage aft of the rear wing spar and fed by air intakes on the sides of the forward fuselage beneath the cockpit canopy, and each of the engines would be enclosed in stainless steel casings separating them from each other and the rest of the aircraft. The Model 1163 would have the wing panels folded fore and aft of each other over the fuselage in order to easily accommodate itself aboard an aircraft carrier, and the nose section and a portion of the vertical stabilizer could also fold back. It had a top speed of 578 mph (930 km/h), a range of 2,595 miles (4,809 km), a service ceiling of 46,800 feet (14,265 meters), a maximum take-off weight of 52,000 lb (23,587 kg), and a climb rate of 5,170 ft/min (26.26 m/s). Armament was to consist of four 20 mm machine guns, two in the nose and two in a power-operated tail turret, and the tricycle landing gear had a narrow track and twin nosewheels. The Douglas company had opted to use turbojets rather than turboprops for the Model 1163 because it deemed a turbojet-powered escort fighter to have greater all-round climb performance in contrast to a turboprop design requiring an auxiliary turbojet to attain the climb rate specified in the OS-112 specification. Very little is known regarding the El Segundo division's D-585 escort fighter project, other than the fact that it was conceived in April 1948, and because no drawings or data exist in the BuAer section of the National Archives, the D-585 probably was not submitted for the OS-112 specification.

Drawing of the Lockheed L-180-2 from the project documents (dated July 1948)

Even before Douglas unveiled the Model 1163 proposal, Lockheed envisaged five distinct designs for combat aircraft in July 1948 under the designation L-180. The L-180 iteration submitted for the OS-112 requirement was the L-180-2, was a backswept wing aircraft with a length of 55 feet (16.76 meters) and wings spanning 81 feet 6 in (24.84 meters) when unfolded and 33 feet (10.06 meters) when folded. The L-180-2 was powered by two Allison T40 turboprops driving eight-blade counter-rotating propellers 13 feet (3.96 meters) in diameter, and to accommodate itself aboard the Oriskany-class aircraft carriers, it had the outboard wing sections fold to the rear. Armament consisted of four 20 mm machine guns, two in the nose and two in a tail turret, and upward- and downward-facing APS-29 radars were fitted aft of the fuel tanks behind the cockpit. Aware that the Navy would judge the L-180-2 design too slow and heavy to operate from small carriers if it were evaluated, Lockheed saw its design for a carrier-based version of the XF-90, the L-180-3, as a lighter alternative to the L-180-2 although the range of the L-180-3 would fall well short of the combat radius specified in the OS-112 parameters. Although outside the scope of this post, it should be noted that Lockheed saw the L-180-5 carrier-based strategic jet bomber design as having the potential to work in tandem with the L-180-3 when necessary to achieve the 1,381 mile combat radius on select combat missions.

All the design submissions to OS-112, including the Douglas 1163 and Lockheed L-180-2, were very interesting escort jet fighter projects, but in the end the US Navy discarded the long-range escort fighter concept before it could evaluate any of designs to decide which proposal should be ordered because the first successful nuclear weapons test by the USSR in September 1949 and deployment of the Tupolev Tu-4 strategic bomber (the Soviet copy of the B-29 Superfortress) made the Navy's need for an all-new carrier-based interceptor to tackle the emerging threat of nuclear-armed Soviet strategic bombers more urgent. Even if either the L-180-2 or Model 1163 had been selected by the Navy to enter full-scale development, they would have not been fast enough to take on Soviet jet fighters even while offering protection for the AJ Savage or the future A-3 Skywarrior if those aircraft conducted nuclear strike missions over the USSR.

References:  

Buttler, T., 2013. Early US Jet Fighters: Proposals, Projects, and Prototypes. Manchester, UK: Hikoki Publications.