Lockheed YP-24
The Lockheed-Detroit YP-24 was an American prototype two-seat fighter aircraft developed in the early 1930s by the Lockheed-Detroit joint venture, marking the company's first venture into military fighter design.[1][2] It featured a low-wing monoplane configuration with retractable landing gear and enclosed tandem cockpits, powered by a single 600 horsepower Curtiss V-1570-23 Conqueror inline engine, and was intended as a faster replacement for the Berliner-Joyce P-16.[1][2] Designed by Robert J. Woods as a private venture amid U.S. Army Air Corps (USAAC) budget constraints, the YP-24 evolved from Lockheed's earlier civil transports like the Sirius and Altair, incorporating a mixed metal-and-wood construction with a metal fuselage and wooden wings.[1][2] The sole prototype, initially designated XP-900, made its first flight in 1931 and was delivered to Wright Field for evaluation on September 29, 1931, where it demonstrated superior performance with a maximum speed of 235 miles per hour, a cruising speed of 215 miles per hour, a range of 556 miles, and a service ceiling of 25,000 feet.[1][2] Armament included one fixed forward-firing .50-caliber machine gun, one fixed .30-caliber machine gun, and one flexible .30-caliber machine gun for the rear seat, positioning it for both pursuit and light attack roles.[2] An attack variant, proposed as the Y1A-9, was also considered.[1] Despite its innovations—including being the first USAAC fighter with a low-wing layout, retractable undercarriage, and fully enclosed cockpits—the program was short-lived.[2] The prototype crashed on October 19, 1931, during landing gear tests at Wright Field, with the pilot parachuting to safety, but the incident, combined with the Detroit-Lockheed company's financial troubles and subsequent bankruptcy in 1932, led to the cancellation of planned production orders for five Y1P-24 fighters and four Y1A-9 attack aircraft.[1][3][2] No further units were built, though the design influenced subsequent developments, notably the Consolidated P-30 fighter after Woods joined that firm.[1][2]Background and design
Company context and project origins
The predecessor Loughead Aircraft Manufacturing Company was founded in 1913 by brothers Allan and Malcolm Loughead; it closed in 1921 due to post-World War I market collapse. The Lockheed Aircraft Corporation was established in 1926. Lockheed encountered severe financial difficulties in the mid-1920s. In July 1929, amid ongoing economic pressures, the Detroit Aircraft Corporation acquired 87 percent of Lockheed's assets, reorganizing it as a subsidiary known as Detroit Lockheed to form a broader aviation conglomerate.[4][5] Allan Lockheed, who had played a pivotal role in the company's early innovations including the design of flying boats and monoplanes, vehemently opposed the acquisition, resigned his position, and sold his shares, severing his direct involvement.[4] This merger aimed to stabilize operations but was soon undermined by the onset of the Great Depression, which devastated the aviation industry and led to Detroit Aircraft's bankruptcy in 1932.[5] Against this backdrop of corporate instability, Detroit Lockheed launched the YP-24 project in 1930 as a private venture initiative, independent of immediate government contracts, to demonstrate advanced design capabilities and attract military interest.[3] The effort drew inspiration from the Lockheed Altair, a successful single-engine sport monoplane introduced in 1930 that featured innovative retractable landing gear and cantilever wings, adapting these elements to a fighter configuration.[1] This endeavor represented the first aircraft explicitly conceived as a pursuit fighter under the Lockheed banner, shifting focus from civilian transports toward military applications amid the company's push for relevance.[3] The project aligned with evolving requirements from the U.S. Army Air Corps, which in the late 1920s had established specifications under its Type V category for two-seat pursuit aircraft to enhance reconnaissance and combat versatility beyond single-seat biplanes.) These needs reflected a broader doctrinal transition in the Air Corps toward monoplane designs for improved speed and aerodynamics, as biplanes like the Boeing P-12 proved increasingly obsolete against emerging threats. Leading the conceptual design was Robert J. Woods, Detroit Lockheed's chief engineer based in the Michigan facilities, whose expertise in monoplane structures shaped the YP-24's foundational low-wing, all-metal fuselage layout to meet these performance demands.[6]Airframe and systems features
The Lockheed YP-24 featured a hybrid airframe construction that combined an all-metal semi-monocoque fuselage with fabric-covered wooden wings, reflecting a pragmatic approach to leveraging existing components for rapid prototyping.[2] The fuselage, built by Detroit Aircraft, provided structural rigidity and aerodynamic smoothness, while the wings—sourced from Lockheed in California—were essentially identical to those of the Altair transport, measuring a wingspan of 42 ft 9.5 in (13.04 m) to maintain proven lift characteristics.[7] This design choice allowed for cost-effective development amid the economic constraints of the early 1930s, with the overall aircraft length reaching 28 ft 9 in (8.76 m).[2] In its two-seat configuration, the YP-24 accommodated a pilot and a gunner/observer seated in tandem within fully enclosed cockpits, marking an early adoption of this feature in U.S. Army Air Corps fighters for improved crew protection and visibility. The low-wing monoplane layout contributed to enhanced stability and maneuverability, positioning the wings below the fuselage for a lower center of gravity. The aircraft utilized retractable main landing gear with a fixed tailwheel, retracting inward into the wings to reduce drag during flight.[2] The design incorporated provisions for dual roles, including ground attack capabilities in proposed variants such as the A-9, with underwing bomb racks to carry conventional ordnance.[1] Armament in the initial design phase emphasized pursuit functionality, featuring synchronized forward-firing machine guns through the propeller arc and a flexible rear-mounted gun for defensive fire from the observer's position. These elements underscored the YP-24's intent as a versatile platform bridging fighter and attack requirements.Development and testing
Prototype construction
Construction of the sole Lockheed YP-24 prototype began in early 1931 through collaboration between Lockheed in Burbank, California, and the Detroit-Lockheed subsidiary, following the completion of a mockup in March of that year.[3][8] To expedite development amid tight timelines, the project incorporated modified components from the existing Lockheed Altair transport design, including elements of its cantilever monoplane wing structure and retractable undercarriage system.[6][1] The wooden wings were built in Burbank, while the metal fuselage and tail surfaces were constructed in Detroit, with final assembly there. The prototype, assigned the manufacturer serial XP-900 and later USAAC serial 32-320 upon military acquisition, faced significant financial and logistical hurdles stemming from the instability of the Lockheed-Detroit subsidiary, which handled aspects of the build in collaboration with the parent company.[8][2] Reliance on pre-existing tooling from the Altair production line helped mitigate some delays, but the broader economic pressures on Detroit Aircraft Corporation—culminating in its bankruptcy declaration shortly after the prototype's completion—complicated resource allocation and coordination between facilities.[9] By mid-1931, assembly was sufficiently advanced to allow the prototype's first flight during manufacturer's trials in the summer of 1931 in Detroit, Michigan, marking the completion of the airframe with its metal fuselage, wooden wings, and Curtiss V-1570 Conqueror engine installation.[6][3][8] Handover preparations to the U.S. Army Air Corps proceeded smoothly thereafter, with the aircraft formally delivered and redesignated YP-24 on September 29, 1931, at Wright Field.[3][8]Flight trials and initial performance
The prototype of the Lockheed YP-24, initially designated as the XP-900, made its maiden flight in the summer of 1931 during manufacturer's trials in Detroit, Michigan, piloted by company test pilots.[6][8] This initial outing marked the first flight of a fighter aircraft designed by the Lockheed firm and highlighted the transition to advanced monoplane designs in U.S. military aviation. The tests focused on validating the basic flight envelope and confirming the aircraft's operational viability before handover to the U.S. Army Air Corps.[3] During these factory-led trials, the YP-24 demonstrated notable handling advantages inherent to its low-wing monoplane layout, offering enhanced responsiveness and maneuverability over the biplane fighters prevalent at the time, such as the Berliner-Joyce P-16. The two-seat configuration provided stable flight characteristics, with the enclosed cockpits contributing to pilot and observer comfort during extended evaluations. Pilots reported positive feedback on the aircraft's agility, which allowed for confident execution of basic aerobatic and tactical maneuvers without the drag penalties associated with biplane structures.[6] Performance data from the initial tests underscored the prototype's potential, recording a climb rate of 1,820 feet per minute and a service ceiling of approximately 25,000 feet, metrics that positioned it ahead of contemporaries like the Curtiss P-6E. These results were achieved through the integration of the 600 hp Curtiss V-1570-23 Conqueror engine, which enabled top speeds around 235 mph in level flight. Minor refinements, including adjustments to the trim system for improved longitudinal stability, were implemented during the trial period to optimize handling before the aircraft's delivery to Wright Field on September 29, 1931.[2]Evaluation and cancellation
Military procurement and assessment
The United States Army Air Corps purchased the sole prototype of the Lockheed YP-24 on September 29, 1931, following its delivery to Wright Field for official evaluation as a pursuit aircraft.[2][6] Initial trials at Wright Field in late 1931 involved assessing the YP-24's performance in comparison to contemporaries, including the two-seat Berliner-Joyce P-16 and the single-seat Curtiss P-6E Hawk, as well as emerging monoplanes like the Boeing P-26 Peashooter.[2][6] The aircraft demonstrated superior speed, achieving 235 mph—40 mph faster than the P-16 and 42 mph faster than the P-6E—along with a climb rate of 1,820 ft/min.[2][6] Evaluators highlighted the YP-24's strengths in its advanced low-wing monoplane design with mixed metal and wood construction, which featured retractable landing gear and enclosed cockpits—innovations that marked it as the first such fighter for the Army Air Corps.[6][2] Its two-seat configuration also offered versatility for both pursuit and ground-attack missions, positioning it as a potential replacement for older biplane designs.[6] These promising results prompted an initial order on September 23, 1931, for five Y1P-24 pursuit fighters and four Y1A-9 attack variants, valued at $250,000, though production was held pending comprehensive evaluation of the prototype.[2][8] The Y1A-9 was envisioned with a turbo-supercharged Curtiss V-1570-27 engine, enhanced armament, and bomb racks to emphasize its attack role.[6]Crash incident and project end
On October 19, 1931, during U.S. Army Air Corps testing at Wright Field in Dayton, Ohio, the sole Lockheed YP-24 prototype (serial 32-320) was destroyed in a crash caused by a failure in the landing gear extension system.[10] The undercarriage lever broke while the gear was in the up position during an evaluation flight, preventing the pilot, Lieutenant Harrison Crocker, from executing a planned wheels-up landing.[11] Crocker was ordered to bail out and did so successfully, with no fatalities reported.[12] The incident led to an immediate grounding of the aircraft, as it was the only prototype, and prompted an investigation that found no fundamental flaws in the overall design.[11] However, the crash highlighted vulnerabilities in the landing gear mechanism under operational stresses.[10] Just eight days later, on October 27, 1931, the Detroit Aircraft Corporation, which had collaborated with Lockheed on the project, entered receivership amid the Great Depression's economic pressures. This financial collapse directly resulted in the cancellation of recent orders placed by the Army Air Corps on September 23, 1931, for five Y1P-24 pursuit variants and four Y1A-9 attack versions. Compounding the issues, the parent Lockheed company filed for bankruptcy in June 1932, further sealing the program's fate.[9] The YP-24, intended as Lockheed's inaugural fighter design, was ultimately shelved, redirecting the company's efforts toward other civilian and military projects under new ownership.Specifications and variants
General characteristics and armament
The Lockheed YP-24 was a two-seat fighter prototype designed for the United States Army Air Corps, featuring a crew of one pilot and one gunner positioned in tandem enclosed cockpits.[2][1] Key physical dimensions included a length of 28 feet 9 inches (8.76 m), a wingspan of 42 feet 9.5 inches (13.04 m), a height of 8 feet 6 inches (2.59 m), and a wing area of 292 square feet (27.1 m²).[2] Weight specifications comprised an empty weight of 3,010 pounds (1,365 kg) and a loaded weight of 4,360 pounds (1,978 kg).[2][1] The aircraft was powered by a single Curtiss V-1570-23 Conqueror V-12 liquid-cooled inline piston engine rated at 600 horsepower (447 kW).[1][3]| Characteristic | Specification |
|---|---|
| Crew | 2 (pilot and gunner) |
| Length | 28 ft 9 in (8.76 m) |
| Wingspan | 42 ft 9.5 in (13.04 m) |
| Height | 8 ft 6 in (2.59 m) |
| Wing area | 292 sq ft (27.1 m²) |
| Empty weight | 3,010 lb (1,365 kg) |
| Loaded weight | 4,360 lb (1,978 kg) |
| Powerplant | 1 × Curtiss V-1570-23 Conqueror V-12, 600 hp (447 kW) |