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FAF EFW N-20 Aiguillon (Sting / Stinger)

Jet-Powered Fighter Prototype

The EFW N-20 Stinger program for Switzerland netted just one completed, flyable example and an unpowered glider.
Authored By: Staff Writer | Edited: 8/16/2018
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Year: 1952
Status: Cancelled
Manufacturer(s): Eidgenossische Flugzeugwerke (EFW) - Switzerland
Production: 1
Capabilities: Fighter; X-Plane;
Crew: 1
Length: 41.01 ft (12.5 m)
Width: 41.34 ft (12.6 m)
Height: 10.27 ft (3.13 m)
Weight (Empty): 19,180 lb (8,700 kg)
Weight (MTOW): 26,455 lb (12,000 kg)
Power: 4 x Sulzer Swiss "Mamba" turbofan engine developing 1,400 lb of thrust each.
Speed: 621 mph (1,000 kph; 540 kts)
Ceiling: 36,089 feet (11,000 m; 6.84 miles)
Range: 311 miles (500 km; 270 nm)
Operators: Switzerland (cancelled)
Like other global air services at the end of World War 2 (1939-1945), the Swiss Air Force looked to stock its inventory with a fleet of modern jet-powered fighters. The task was not an easy one, considering the nation opted to indigenously solve its requirement through local design and development. The initiative was headed by the "N-20", a product featuring swept-back wing mainplanes, a single tail fin unit, seating for one, and four turbojets buried within the main wing elements. Despite the work undertaken, the endeavor managed only one completed prototype but nonetheless netted considerable experience for Swiss engineers at Eifgenossische Flugzeugwerke (EFW) - the Federal Aircraft Factory.

From the outset, the N-20 was intended to lay the groundwork for a finalized service-quality aircraft but much work would be needed in terms of research to bring such a complex product about. Design work began as early as 1945 and a prototype contract followed in May of 1948. The aircraft was given the name of "Aiguillon" meaning "Sting" or "Stinger".

Engineers had fleshed out a modern, advanced fighter for the time - one lacking true horizontal tailplanes and featuring, not one or two but four, engines buried within the wing mainplanes themselves. These were to aspirate from openings at the wing leading edges and exhaust through ports along the wing trailing edges. The wings themselves were rather thick as a result but still deemed effective for the role of fighter. The pilot was given a commanding view over, and around, the nose section thanks to the well-forward placement of the cockpit and its elevated position. The fuselage was oblong in its forward profile and tapered nicely towards the empennage where the sole vertical fin was seated. The undercarriage was of a tricycle arrangement with each leg double-tired for rough-field operations. For power, the Sulzer Swiss "Mamba" SM-1 turbofan of 1,400lb thrust (each) was selected - these developed from the British Armstrong Siddeley Mamba turboprop.

Before any true work could be had on the flying prototype, a wooden glider of the product was constructed mimicking the final design at 3/5 scale. This entry was known as "N-20.01" and recorded its first flight on April 17th, 1948 when it was taken up by "tug" aircraft. With the body constructed largely of wood, the skinning was of fabric. To expedite its journey into the air, the undercarriage was constructed from the World War 2-era German Messerschmitt Bf 109 prop-driven fighter (making up the main legs) and the British de Havilland "Vampire" jet fighter (the nose leg) - all were retractable. The glider was heavily damaged in a crash landing that occurred on July 1st, 1949 and was not rebuilt.

The second test article became N-20.02 "Arbalete" ("Crossbow") and four low-thrust Turbomecca "Pimene" engines were now installed in a four individual pods set in an "over-under" arrangement at each wing trailing edge. Its overall dimensions were similar to the N-20.01 glider form. The aircraft completed a first-flight on November 16th, 1951 and marked the first-ever indigenous Swiss jet aircraft to be realized. The Arbalete showcased exceptional maneuverability for its time in the air and proved valuable in furthering the N-20 program as a whole.

The N-20.10 became the full-scale offering of the N-20 program but its initial engine fit proved underpowered so they were reworked to complete the prototype which accomplished some ground-running trials and test "hops" for the first time on April 8th, 1952. An off-shoot of the N-20.10, intended to overcome the underpowered issue, became "N-20.20" designed to install a single Rolls-Royce "Avon" or Armstrong Siddeley "Sapphire" turbojet engine in each wing root. As a result the mainplanes could be made thinner and the undercarriage track narrower. However this product did not see the light of day.

The N-20 program was cancelled by the Swiss government shortly after the April 1952 run of test article N-20.10. The Arbalete continued to be used in research up until 1954 and recorded some ninety-one flights. The FFA "P-16" - detailed elsewhere on this site - continued the Swiss journey to delivering a homegrown fighter jet, the second such attempt by the country. However, this product too would fail to net the country a viable combat platform - the result being procurement of foreign fighter types for the foreseeable future.



Variants / Models

• N-20 "Aiguillon" - Base Series Designation
• N-20.01 - 3/5 scale wood-and-fabric research glider; lost in crash landing.
• N-20.02 "Arbalete" - Developmental aircraft based on the glider form; fitted with 4 x Turbomeca Pimene I turbojet engines of 242lb thrust each; single example completed.
• N-20.10 "Aiguillon" - Full-scale prototype; single example completed; fitted with Sulzer Swiss "Mamba" turbofan engine.
• N-20.20 - Proposed single engine variant fitting either Rolls-Royce Avon or Armstrong Siddleye Sapphire turbojet engine; abandoned.
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