Douglas 1112, 1155, 1211, and 1240 parasite aircraft carrier: unbuilt competitors to the B-52 Stratofortress from Santa Monica

The Boeing B-52 Stratofortress is one of the most formidable weapons in the US armory, an expression of the US capability to project long-range air power abroad (next year, in April 2022, the B-52 will mark the 70th anniversary of its first flight, continuing to serve with the US Air Force despite the development of intended replacements like the XB-70 Valkyrie, B-1 Lancer, and B-2 Spirit). A few years ago, I finally had the chance to see the B-52 in person when I paid my first visit to the March Field Air Museum in Riverside, California, and all I have to say is that the B-52 was truly impressive in size as I had seen in books on post-1945 US military aviation, unusually using outrigger landing gear to support its huge wingspan. The history of design and early development of the legendary and venerable Boeing B-52 has been discussed by Buttler (2010), Remak (2016), and Yenne (2012), but almost lost in talk of the early development of the B-52 Stratofortress are intercontinental bomber designs from the Santa Monica division of the Douglas company to compete with design studies for the Boeing B-52 but also proposals from Convair and Martin for the B-52 competition.

Desktop model of the six-engine version of the Douglas Model 1155 strategic bomber 

In May 1947, the Douglas company conceived a design for a piston-powered long-range heavy bomber under the company designation Model 1112, of which two proposals were devised. The Model 1112A was a vastly scaled-up version of the Douglas XB-42 Mixmaster prototype tactical bomber featuring pusher propellers connected by a long shaft to two Pratt & Whitney R-4360 Wasp Major radial piston engines buried in the roots of the straight taper wing. The Model 1112A would have had a length of 92 feet 8 in (28.25 meters) and a wingspan of 118 feet 4 in (36.07 meters), and one variant of the Model 1112A had two auxiliary General Electric TG-190 turbojets in wing nacelles and a wingspan of 138 feet 7 in (42.25 meters). The Model 1112B was similar to the Model 1112A but had a wider fuselage to make room for more fuel. The US Army Air Force rejected the Model 1112 designs because it deemed the Model 1112 inferior to Boeing's initial B-52 designs. Having recognized the obsolescence of piston-powered planes, Douglas returned to the drawing board to conceive a straight-winged intercontinental bomber using jet engines, called the Model 1155. Based on the DC-6 piston-engine airliner, the Model 1155 featured a new leading edge of the wing, an extension of the outer sections of the wing, a longer fuselage, a tail turret similar to that developed for the Boeing B-50 Superfortress, and a bomber nose. It was to have a wingspan of 159 feet 6 in (48.62 meters), a length of 115 feet 8.5 in (35.27 meters), and a maximum take-off weight of 213,800 lb (96,980 kg). Two Model 1155 variants were proposed, one powered by six individual turbojets and another powered by four engines; both designs had the main landing gear housed in the forward part of the inner nacelles. The Model 1155 proposals were submitted to the US Air Force on April 30, 1948, but were rejected later that year.

Desktop model of the Douglas Model 1211J turboprop-powered intercontinental bomber

Douglas returned to the fore of efforts to develop a rival competitor to the Boeing B-52 in 1949 when it when it began design studies for an intercontinental bomber powered by four turboprop engines under the Model 1211 designation. A total of 40 designs for the Model 1211 were worked out in 1949-1950, differing in the wing area and powerplant, and in January 1950 Douglas submitted the 1211J proposal to the US Air Force. By July a design study and operational effectiveness evaluation for nine optimized strategic bombers was completed, with emphasis placed on thin high-aspect ratio wings to offer both intercontinental range and high speed. Zichek (2009) is consulted for drawings and extensive technical details regarding design studies for the Model 1211, but I do wish to summarize a handful of Model 1211 proposals as follows:

• Baseline Model 1211: powered by four turboprops, straight wings
• Model 1211E: backswept wings; powered by four turboprops and two turbojets; wingspan of 188 feet (57.3 meters) and a length of 124 feet 7 in (37.9 meters)
• Model 1211H: Similar to 1211E but with a wingspan of 227 feet 6 in (69.34 meters) and a length of 144 feet 8 in (44.1 meters) 
• Model 1211J: powered by four turboprop engines and four Pratt & Whitney J57 turbojets, with a crew of nine (two pilots, bombardier, radar engineer in the nose, engineer and navigator in the forward fuselage cabin, and three relief crewmen for long combat missions); wingspan as Model 1211H with fuselage 160 feet 6 in (48.92 meters) in length; 322,000 lb (146,060 kg) fully loaded, with a top speed of 518 miles per hour (833 km/h); maximum range 12,658 miles (20,372 km), and 50,000 lb (22,680 kg) of fuel housed in wing drop tanks. Armament comprised 43,000 lb (19,505 kg) of bombs, two photo-flash bombs, and two 20 mm cannons in the tail. Outrigger wheels (to be jettisoned  after takeoff) supported the long wings between the outer engines and the drop tanks. In April 1950, Douglas explored the notion of using the 1211J as a mothership for the Douglas F4D Skyray and Convair XF-92 jet fighters.
• Model 1211K: launch platform to carry an SM-64 Navaho intercontinental cruise missile atop the fuselage on pylons
• Model 1211L: variant of the 1211K with increased fuel capacity.
• Model 1211M: variant of the 1211J with eight Pratt & Whitney J57 turbojets 
• Model 1211N: variant of the 1211J with six J57s.
• Model 1211P: wingspan as 1211J but fuselage slightly shorter
• Model 1211R: powered by four Pratt & Whitney T45 turboprops and two auxiliary Pratt & Whitney J57 turbojets; sub-variants included the 1211R-45 with a wingspan of 195 feet 6 in (59.6 meters), a length of 143 feet 9 in (43.82 meters), a speed of 518 miles per hour (833 km/h), a range of 13,015 miles (20,946 km) a gross weight of 239,000 lb (108,410 kg), and armament comprising 43,000 lb (19,505 kg) bombs and two 20 mm machine guns in the tail, the 1211R-55 with a wingspan of 236 feet (71.9 meters), a length of 164 feet 6 in (50.14 meters), a speed of 518 miles per hour (833 km/h), and a gross weight of 306,000 lb (138,802 kg), and the 1211R-50D with a wingspan of 251 feet (76.5 meters) and a length of 169 feet 4 in (51.61 meters). 
• Model 1211S: similar to the 1211R but with a wingspan of 191 feet (58.21 meters) and a length of 144 feet (43.89 meters)
• Model 1211T: powered by four Pratt & Whitney T45 turboprops and four Pratt & Whitney J57 turbojets; sub-variants included the baseline 1211T with a wingspan of 240 feet (73.15 meters) and a length of 210 feet (64 meters), the 1211T-45 with a wingspan of 210 feet 7 in (64.2 meters) and a length of 195 feet 6 in (59.6 meters), the 1211T-50 with a wingspan of 224 feet 8 in and a length of 207 feet (63.14 meters), and the 1211T-55 with a wingspan of 262 feet (79.86 meters) and a length of 207 feet 2 in (63.14 meters). Outrigger landing wheels were positioned outboard of the outer turboprops.
• Model 1211U: wingspan as 1211S but fuselage 178 feet 7 in (54.43 meters) long.
• Model 1211X: similar to the initial 1211 proposal in having straight wings, but differed in being longer and having increased wingspan; subvariants included the 1211X-45 and 1211X-50 with four T45s and two J57s, the 1211X-55 with four T45s and four J57s.  

Top: Desktop model of the Douglas Model 1240 multi-role carrier aircraft and variety of loads that would have been carried by the Model 1240
Bottom: Desktop models of the Douglas Model 1251A (left) and Model 1265 (right) parasite bombers

As a side note, in late 1950 Douglas investigated a number of versions of the asymmetrical Model 1240 twin-boom, twin-fuselage carrier aircraft project (which had the crew compartment in the left fuselage nose) to carry either parasite fighters, specially designed supersonic bombers, or a huge pod measuring 100 feet (30.5 meters) and loaded with bombs for long-range combat missions. For instance, in February and March 1951, Douglas proposed two supersonic parasite bomber designs to be carried by the Model 1240, the Models 1251A and 1265. both of which had a crew of three. The Model 1251A had three Pratt & Whitney J53 turbojets, two of which could be jettisoned on the return flight with the third situated in the rear fuselage, and it would have carried one specially designed bomb below the center of the fuselage. The wingtip-mounted fuel tanks were to be jettisoned during the attack phase of a combat mission and the supersonic fuel tanks would be discarded during the return leg of the mission. One 1251 proposal dated March 11, 1951 was proposed with two Pratt & Whitney PT2E turboprops and subsonic speed. The Model 1265 was a twin-fuselage design with the cockpit on the port fuselage, and like the 1251A could release the subsonic fuel tanks during a sortie and the supersonic fuel tanks on the return. It could carry a butterfly-tailed single pod below the center wing section containing a specially designed bomb, and two of the J53s were situated in the fuselages with the third housed in a jettisonable pod. Despite offering flexibility as a combat plane in addition to non-combat roles, the Model 1240 was rejected by the US Air Force in 1951 due to its high drag penalty compared to conventional aircraft, while the Model 1251A and 1265 designs remained paper projects only.  

For all its promising potential in terms of size, combat performance, and overall layout, the Douglas Model 1211 and parasite aircraft carrier versions of the Model 1240 would never progress beyond the drawing board. The Boeing B-52 by now had entered full-scale development along with the Convair YB-60 all-jet derivative of the B-36 Peacemaker, and the US Air Force certainly found the Model 1211  and Model 1240 projects too ambitious and too complex to be earmarked for full-scale development. In the meantime, the Soviet Union's Tupolev Tu-95 'Bear' turboprop bomber, utilizing the same design philosophy as the Model 1211, did proceed to the hardware phase, making its first flight on November 12, 1952, and it remains the only intercontinental bomber with turboprop engines in operational service, an anomaly considering that all other strategic bombers in service today are jet-powered.

[EDIT: Thanks to a copy of the revised edition of the American Secret Projects volume by Tony Buttler about bomber, attack, and anti-submarine aircraft designs from the 1945 to 1974 interval that I got recently, but also the comprehensive monograph by Zichek (2010), it is now clear that the parasite bomber designs intended for launch from the Model 1240 received the company designations Model 1251 and Model 1265. Although not exclusively a strategic bomber in the strictest sense, the Model 1240 was heavy enough to carry smaller aircraft and war material housed in underwing pods.]

References:

Buttler, T., 2010. American Secret Projects: Bombers, Attack, and Anti-Submarine Aircraft 1945 to 1974. Hinckley, UK: Midland Publishing.

Buttler, T., 2021. American Secret Projects 4: Bombers, Attack, and Anti-Submarine Aircraft 1945 to 1974. Manchester, UK: Crécy Publishing.

Remak, J., 2016. Boeing B-52 Stratofortress: Warrior Queen of the USAF. Stroud, UK: Fonthill Media.

Yenne, B., 2012. B-52 Stratofortress: The Complete History of the World's Longest Serving and Best Known Bomber. Minneapolis, MN: Zenith Press. ISBN 978-1610586726.

Zichek, J.A., 2009. The B-52 Competition of 1946…and Dark Horses from Douglas, 1947-1950 (American Aerospace Archive Number 3). La Jolla, CA: American Aerospace Archive. 

Zichek, J.A., 2010. Mother Ships, Parasites, & More: Selected USAF Strategic Bomber, XC Heavy Transport and FICON Studies, 1945-1954 (American Aerospace Archive Number 5). La Jolla, CA: American Aerospace Archive.