Hughes XF-11
The Hughes XF-11 (redesignated XR-11 in 1948) was a prototype military reconnaissance aircraft designed and flown by Howard Hughes and built by Hughes Aircraft Company for the United States Army Air Forces (USAAF). Although 100 F-11s were ordered in 1943, the program was delayed beyond the end of World War II, rendering the aircraft surplus to USAAF requirements; the production contract was canceled and only two prototypes were completed. During the first XF-11 flight in 1946, piloted by Hughes, the aircraft crashed in Beverly Hills, California, and was destroyed, critically injuring him.[2][3] The second prototype first flew in 1947 but was used only briefly for testing before being scrapped in 1949.[4][5][6] The program was controversial from the beginning, leading the United States Senate to investigate the XF-11 and the Hughes H-4 Hercules flying boat in 1946–1947.
"XF11" redirects here. For the near-Earth asteroid, see (35396) 1997 XF11.Development[edit]
The F-11 was intended to meet the same USAAF operational objective as the Republic XF-12 Rainbow: a fast, long-range, high-altitude photographic reconnaissance aircraft. A highly modified version of the earlier private-venture Hughes D-2, it resembled the Lockheed P-38 Lightning, but was much larger and heavier.[7] Hughes Aircraft Company founder Howard Hughes had first promoted the D-2 as a "pursuit type airplane", (i.e. a fighter aircraft),[8][9] but it lacked both the maneuverability of a fighter and the load-carrying capacity of bomber, and could not accommodate required military equipment; additionally, the USAAF Air Materiel Command (AMC) objected to its wooden Duramold construction due to a perceived lack of durability under fire. Hughes was determined to win a military contract but soon realized that the USAAF was highly unlikely to accept the D-2, so he began petitioning USAAF leaders to issue a contract to redesign it for photographic reconnaissance, and spent several million dollars hiring additional staff and opening a new engineering office for the effort.[10][11]
Hughes campaigned the USAAF in Washington, enlisting his father's friend, Secretary of Commerce Jesse Holman Jones, who met with President Franklin Roosevelt in June 1942 to discuss the project. The outcome of the visit was inconclusive.[12] However, around this time, USAAF leaders were debating the need for a dedicated, purpose-designed reconnaissance aircraft with greater capabilities than existing converted fighters and bombers. The need was particularly acute in the Pacific theater because the loss of air bases in China placed many strategic targets in Japan beyond the range of almost all existing Allied aircraft; the Boeing B-29 Superfortress would be able reach these areas, but some USAAF leaders objected to diverting this valuable strategic bomber to the long-range reconnaissance role. In January 1943, the USAAF launched a program to procure a dedicated reconnaissance aircraft with superior range, speed, and altitude capabilities. Preliminary specifications were issued in April of that year.[13] Boeing proposed a heavily modified B-29, while the Lockheed Aircraft Company proposed a version of its experimental XP-58 fighter. The Hughes Aircraft and Republic Aviation proposals would become the XF-11 and XF-12 respectively.[14]
Howard Hughes found out that Colonel Elliott Roosevelt, the president's son and a USAAF reconnaissance commander, would visit Hughes Aircraft in August 1943 in the process of surveying reconnaissance aircraft proposals. When Roosevelt and his team arrived on August 11, Hughes' public relations agent John Meyer showed them the D-2 prototype, took them on a tour of several Hollywood film studios, and introduced Roosevelt to actress Faye Emerson, whom Roosevelt would later marry. Meyer encouraged Roosevelt and his entourage to stay in a private home at his expense, and when Roosevelt demurred, Meyer paid their hotel bill. After Roosevelt left, Meyer invited him to parties he was hosting in New York City and took him to Manhattan nightclubs, where Meyer paid. On August 20, Roosevelt submitted a report to General Henry "Hap" Arnold, chief of the U.S. Army Air Forces, recommending the Hughes proposal.[15] Arnold ordered 100 F-11s for delivery beginning in 1944, overriding the strenuous objections of AMC, which held that Hughes Aircraft lacked the industrial capacity and track record to deliver on its founder's promises, and recommended that Arnold should instead approve the reconnaissance version of the XP-58.[16][17][18] Arnold later regretted the decision, saying that he made it "much against my better judgment and the advice of my staff" after consultations with the White House.[17][18]
A preliminary $43 million[18] contract issued on 11 October 1943 was contested by Hughes, who sought $3.6 to $3.9 million in compensation for the development of the D-2, and objected to AMC's requirements for all-metal construction, self-sealing fuel tanks, and various other major design changes that undermined his contention that the F-11 was directly derived from the D-2.[18][19] The USAAF strongly objected, arguing that the D-2 project was initiated without USAAF input, and that Hughes had continuously withheld information about the aircraft.[20] In another complication, the War Production Board (WPB) wanted Hughes to build a new assembly plant near Hughes Tool Company headquarters in Houston, where labor costs were lower than in southern California. The WPB eventually relented and allowed Hughes Aircraft to use its existing Culver City, California, assembly plant, and the USAAF made some small design concessions; however, Hughes failed to secure full reimbursement and ultimately agreed to most of the design changes, notably including the elimination of Duramold. The protracted negotiations consumed the better part of ten months, and the final contract was awarded on 1 August 1944.[19] Hughes was awarded $1.6 million in reimbursement.[20]
The program was plagued by managerial and logistical delays. By early 1944, Hughes was suffering from mental strain from the demands of managing both the F-11 and Hughes H-4 Hercules projects, and had become withdrawn. Warned that the USAAF was considering canceling the F-11 due to a lack of progress, Hughes hired Charles Perrell, former vice president of production at Consolidated Vultee, to manage the program, promising him full and unconditional control.[21] Perrell found Hughes Aircraft rife with inefficiency and suffering from a "complete lack of experience in the design and construction of airplanes in general." His efforts to reorganize were hindered by resistance from senior Hughes Aircraft engineers, who were accustomed to a freewheeling work atmosphere, and from Hughes Tool executives who feared that Perrell would usurp their authority over the aircraft company.[22] 21 engineers, including chief engineer Ed West, resigned in a May 1944 dispute over their offices being moved from Brea, California, to the Culver City plant.[1] The prototype's wings–subcontracted to Fleetwings–were delivered six months behind schedule in April 1945.[23] With the end of the European war in May 1945, the order for 100 F-11s was reduced to just three, a static test model and the two prototypes, and the USAAF de-prioritized the project.[23][24] The engines were delivered seven months behind schedule in September 1945.[23] By this time, Perrell had been successful in reforming the program, but there was no longer any impetus to deliver 98 production aircraft, and Hughes returned from self-imposed exile and began to interfere despite his earlier promises not to do so. Relations between the two men deteriorated and Hughes had Perrell fired in December.[25]
Design[edit]
The XF-11 emerged as a tricycle landing gear, twin-engine, twin-boom all-metal monoplane with a pressurized central crew nacelle and a much larger wingspan and higher aspect ratio than the P-38 or the D-2.[1][26] The aircraft was of conventional aluminum alloy construction with flush riveted skin. The wings were equipped with single-slotted Fowler flaps; roll control was provided by mid-chord spoilers at high speeds and by ailerons near the wingtips at low speeds. To provide added fuel capacity and range, hardpoints were mounted under the wings for 700-US-gallon (2,600 L; 580 imp gal) auxiliary drop tanks, and design drawings also indicated provisions for mounting 600-US-gallon (2,300 L; 500 imp gal) auxiliary tip tanks. However, there is no evidence that auxiliary fuel tanks were ever fitted to the prototypes during flight tests.[27]
The aircraft was designed to be flown by a crew of two in laterally staggered tandem seating, with the pilot sitting forward and a navigator/photographer sitting behind and to the right; the navigator/photographer could crawl into the nose to service the cameras in flight. A dedicated photographic systems technician could also sit in the lower nose compartment to service the cameras.[28] The nose compartment housed a Fairchild K-17 camera in the transparent nose cone together with two additional cameras aimed outwards through windows. Two additional downward-facing Fairchild K-22 cameras were fitted in the left tail boom behind small retractable doors. Unlike the competing Republic XF-12, the XF-11 had no provisions for developing films in flight, for mounting trimetrogon cameras (used for determining topography), nor for dropping flash bombs for nighttime missions. Fitting trimetrogon cameras to the production F-11 was considered; however, due to the lack of provisions for flash bombs, the USAAF intended to restrict the F-11 to daytime missions only.[29]
Although the USAAF intended for the aircraft to be fitted with an ice protection system, Hughes engineers were unable to design a satisfactory system before the test program; as a compromise, the USAAF allowed ice protection to be omitted from the prototypes, and accordingly agreed that test flights would take place only under visual flight rules,[30] thus avoiding instrument meteorological conditions where atmospheric icing is more likely.
The XF-11 was powered by a pair of Pratt & Whitney R-4360-31 28-cylinder radial engines rated at 3,000 horsepower (2,200 kW) of takeoff power at sea level and 2,500 horsepower (1,900 kW) at 33,000 feet (10,000 m).[30] Contra-rotating propellers were originally a contract design requirement for both the XF-11 and XF-12, and Hughes Aircraft and Republic Aircraft were given a choice between competing designs from Hamilton Standard and Aeroproducts.[31][a] The first XF-11 prototype was equipped with a pair of dual four-bladed, variable-pitch, contra-rotating Hamilton Standard propellers;[23][30] these proved troublesome in testing, having a tendency to suddenly and inexplicably reverse pitch.[23] The second prototype was equipped with conventional four-bladed, variable-pitch Curtiss Electric propellers identical to those fitted to the P-61 Black Widow.[30]
Data from Jane's all the World's Aircraft 1947[58]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
Related lists