The Lockheed XFV (Salmon) was an experimental vertical takeoff and landing (VTOL) aircraft, featuring a tailsitter design, powered by a turboprop engine, and intended for convoy protection.
In brief
The Lockheed XFV, also known as the Salmon, was an innovative aircraft developed in the early 1950s. This experimental tailsitter prototype, created for the U.S. Navy, was designed to demonstrate the feasibility of a vertical takeoff and landing (VTOL) fighter. The XFV aimed to provide convoy protection without the need for large aircraft carriers. It featured a distinctive design with a cruciform tail and contra-rotating propellers powered by an Allison XT40-A-14 turboprop engine. Despite its ambitious concept, the XFV faced significant challenges. It struggled with the limitations of its engine and control complexities, which ultimately led to the cancellation of the program in 1955. The XFV’s unique design and its role in the advancement of VTOL technology remain notable in aviation history.
The Lockheed XFV (Salmon) represents a unique chapter in the history of aviation, embodying the adventurous spirit of aircraft design in the early Cold War period. As an experimental VTOL aircraft, the XFV was part of a broader effort to explore new technologies and capabilities in a rapidly evolving aerospace landscape.
History of the Development of the Lockheed XFV (Salmon)
The development of the Lockheed XFV (Salmon) must be contextualized within the post-World War II era, a time characterized by rapid technological advancements and a heightened focus on military innovation. This period saw the rise of turboprop and turbojet technologies, prompting several nations, including the United States, to explore the potential of VTOL aircraft.
The U.S. Navy’s requirement for a shipborne VTOL aircraft capable of operating from small deck spaces, issued in 1950, sparked the development of the Lockheed XFV. The concept was to enable convoy-type ships to have an armed protective measure against aerial threats. Lockheed’s response to this requirement was an aircraft that sat vertically when at rest and took off and landed in the same posture.
Designed by Art Flock, the XFV featured a unique appearance with the pilot positioned at the front, a largely unobstructed canopy, and a fuselage tapered at both ends. The aircraft had a cruciform tailplane arrangement and short-span mid-mounted wings. It was powered by an Allison XT40-A-14 turboprop engine, which was initially an interim solution before the more powerful YT40-A-14 model. The XFV was intended to be armed with 4 x 20mm cannons or 48 x 2.75″ aerial rockets in its wingtip pods.
Lockheed’s contract to produce the XFV-1, won against its rival Convair, was awarded by the U.S. Navy on April 19, 1951. The XFV-1, nicknamed “Salmon” after Lockheed’s Chief Test Pilot Herman “Fish” Salmon, made its first unintentional hop in 1953 during taxi tests and its first official flight on June 16, 1954. However, the project faced significant challenges, including delays due to the unavailability of the specific engine required for full VTOL capabilities and the aircraft’s inability to match the speed of contemporary fighters. The program was eventually canceled in June 1955 without achieving a single vertical takeoff or landing.
Design of the Lockheed XFV (Salmon)
The design of the Lockheed XFV was marked by several innovative features and notable challenges. The aircraft’s vertical “tailsitter” stance, necessary for its VTOL capabilities, was a distinct departure from conventional aircraft designs. This posture required the pilot to land and take off in a vertical position, which presented unique piloting challenges.
The XFV’s propulsion system was centered around the Allison XT40-A-14 turboprop engine, which powered two sets of three-bladed contra-rotating propellers located at the aircraft’s nose. This engine setup was meant to provide sufficient thrust for vertical takeoff and landing. However, the aircraft initially used the XT40-A-6 engine, an interim solution that failed to meet the required VTOL thrust. This led to the addition of a cumbersome, non-retractable undercarriage for horizontal flight testing.
The aircraft’s structural design included a tube-like fuselage with extreme tapering towards the rear, a cruciform tailplane arrangement, and mid-mounted wings with pods extending beyond the leading and trailing edges. These design elements were crucial for the XFV’s intended operational role but also contributed to its complexity and the difficulties encountered during testing.
Performance of the Lockheed XFV (Salmon)
The Lockheed XFV, also known as the “Salmon,” was an experimental tailsitter prototype aircraft developed by Lockheed in the 1950s. Its design was unique, emphasizing vertical takeoff and landing (VTOL) capabilities.
Engine and Power: The XFV was powered by an Allison YT40-A-14 turboprop engine, notable for its substantial power output. This engine, delivering around 5,850 shaft horsepower (4,360 kW), was geared to drive three-bladed contra-rotating propellers.
Speed and Altitude: In terms of performance, the XFV could reach a maximum speed of approximately 580 mph (933 km/h) at altitude. Its service ceiling, or the maximum altitude at which it could fly efficiently, was around 43,000 feet (13,106 meters).
Range: The aircraft had a range of approximately 700 miles (1,126 kilometers), which was a significant distance for a VTOL aircraft of its era.
Comparative Analysis: When comparing the XFV to its contemporaries, it’s important to note that it was an experimental aircraft, primarily focused on testing VTOL capabilities. Its speed and altitude were competitive, but its operational range and practicality in combat scenarios were limited compared to conventional aircraft of the time, such as the F-100 Super Sabre or the Soviet MiG-19.
Variants of the Lockheed XFV (Salmon)
The Lockheed XFV, being an experimental aircraft, did not have multiple variants in the traditional sense. However, there were different stages and configurations in its development:
- XFV-1: The initial prototype design, featuring the Allison YT40-A-14 engine and the distinctive tailsitter landing gear configuration.
- Alternative Configurations: Throughout its development, Lockheed considered various modifications, including different propeller designs and engine setups, to enhance its performance and stability in VTOL operations.
Military Use and Combat of the Lockheed XFV (Salmon)
Armament: The planned armament for the XFV included four 20 mm cannons, which were standard for fighter aircraft of that era. However, the XFV was never equipped with these weapons for its test flights.
Combat and Military Use: The Lockheed XFV never saw combat or active military service. Its role was strictly experimental, aimed at exploring the possibilities and challenges of VTOL flight for fighter aircraft.
Missions and Operations: The XFV was involved in numerous test flights and evaluations, but it did not participate in any military operations or battles, as it never progressed beyond the prototype stage.
Comparative Aircraft and Sales: The XFV did not compete directly with other aircraft in operational scenarios, nor was it sold to other countries. It was a unique concept that stood apart from mainstream fighter aircraft development.
Current Status: The XFV program was ultimately discontinued, and the aircraft did not enter production. It was replaced in interest by more conventional aircraft designs and later by more advanced VTOL designs, such as the Harrier jump jet.
The Lockheed XFV “Salmon” represents an intriguing chapter in aviation history, embodying the innovative spirit and technical exploration of the era. While it demonstrated some impressive capabilities, particularly in its VTOL operations, it was ultimately limited by practical challenges and the rapid advancement of conventional aircraft technology. Its legacy lies in the lessons learned and the technological advancements it spurred in the field of VTOL and aircraft design.
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