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SNCASO SO.6020 Espadon

Assault Fighter-Interceptor Prototype

France | 1948

"SNCASO of France worked on four versions of its SO.6020 jet-powered prototype - none advanced."

Authored By: Staff Writer | Last Edited: 02/20/2019 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.
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The rebuilding French aero-industry went right to work following the close of World War 2 (1939-1945). In March of 1946, the recovering French Air Force (Armee de l'Air) drew up a request for an all-new, all-modern "assault fighter interceptor". The requirement called for, among other qualities, a speed of at least 560 miles-per-hour speeds under jet power, cockpit armoring to protect from hits up to heavy small arms fire, and an armament load out of 6 x 20mm autocannons as standard armament. By this time in history, the French, like other powers around the world, has some time to actively study the German wartime Messerschmitt Me 262 (Schwalbe) jet-powered fighter. As the jet age had dawned, turbojet jet-powered forms were the way of the future regarding military warplanes.

SNCASO, founded in the per-war period during 1936, was handed the development contract to cover three prototypes for such an aircraft on June 28th, 1946. A first-batch of 230 aircraft were planned following the conclusion of successful flight-testing under various conditions. Hundreds more would eventually stock the French Air Force fleet before the end.

The original propulsion scheme was to involve the all-French Rateau SRA-101 turbojet - a powerplant amazingly designed and developed in occupied France during the war. The engine was tested in September of 1946 and increased in power by 1947. However, its low output meant that the project went nowhere and was eventually abandoned come 1948. After this, it was decided to go with the much advanced, and proven, British Rolls-Royce "Nene" Series 100 turbojet of 5,000lb thrust being built locally by Hispano-Suiza.

The SNCASO product became the SO.6020 "Espadon" (meaning "Swordfish"). It carried a clean design look with mid-mounted mainplanes along an elegantly-shaped fuselage and the tail was made up of a conventional arrangement incorporating low-mounted planes and a single vertical fin. The mainplanes were straight-edged with rounded tips - fitted at the exact midway point of the fuselage. There was little sweep along the leading edges but noticeable sweep at the trailing edges. The nose section was long and bullet-shaped, set to house the collection of autocannons ahead of the pilot. The cockpit was lightly framed and positioned ahead of midships with a raised dorsal spine section aft. The pilot would control his aircraft through a column-mounted yoke. All pertinent operating dials would be positioned along the forward instrument panel as usual. To aspirate the single engine installation, semi-circle side-mounted intakes would be used (as opposed to a nose-mounted intake popular in the day). For ground-running, a tricycle undercarriage (retractable was used). The legs were short so as to retract cleanly into the design but this also gave the aircraft a low stance when on the ground.

As in the requirement, the armament would consist of 6 x 20mm autocannons fitted as three guns per side of the nose. Alternatively, the aircraft could sport 2 x 30mm DEFA cannons for more inherent firepower. The design decision to go with side-mounted intakes was deliberate - clearing the nose section to concentrate all of the primary armament there. In addition to this, the nose was already being planned to carry intercept radar (which was never fitted to any of the flyable SO.6020 forms).

The first prototype of the series became SO.6020-1 and a planned first-flight was set for March of 1948 - however this specimen did not record this action until November 12th, 1948 due to equipment delays. This aircraft tested adequately enough even without its planned cockpit pressurization system and armament in place but did not impress on the whole due to a lack of power - rate-of-climb was a considerable failing, particularly for a fighter intended to intercept incoming bandits. The project suffered a serious setback on December 1st, 1949 when a power failure forced a belly-landing to be had. This example would later be fitted with Turbomeca "Marbore" turbojets at the wing tips.

The SO.6020-1 had an overall length of 49 feet, 2.5 inches with a wingspan of 34 feet. Gross weight reached 17,778lb. The sole Nene engine supplied 5,000lb of thrust exhausting through the jetpipe at the base of the rudder fin at rear.

SO.6020-2 was the second prototype of the line and this time was used to incorporate beneficial changes to the design from lessons learned in flying the first protoype. Again, the first flight of this form was delayed from August 1948 until September 16th, 1949. Despite the introduction of flush-mounted intakes, power proved elusive and this specimen went on to become the test article "SO.2026" to evaluate rocket motors (SEPR-25 and SEPR-251). A first-flight of the modified aircraft took place on January 4th, 1952.

SO.6020-3 was brought along as the third contracted prototype and base highly in Prototype 1. As it was intended to showcase a reconnaissance-minded production form, the SO.6020-3 was given a camera-equipped nose for the role. However, it never flew with this assembly for it was modified to become "SO.6025" and, like the SO.6020.2 before it, the SO.6020-3/SO.6025 carried the SEPR-25 auxiliary rocket motor for additional, albeit temporary thrust.

Proposed production interceptors based in the SO.2030-3 design would carry the designation of "SO.6021". To finalize this design, begun in 1947, the aircraft would be given a lighter structure to reduce operating weights, have its wing enlarged for improved stability, feature hydraulic-assisted controls, and seat the pilot in a life-saving ejection seat. All other qualities of the SO.2030-3 were retained. This form was eventually built and flown, for the first time, on June 3rd, 1950. As with other aircraft of the Espadon series, SO.6021 did not proceed and ended its days as a test bed for various engine fits.

To extract something from this project, SNCASO engineers drew up working plans for a 18,408lb ground-attack version of this fighting platform. As is usual for low-level flying aircraft, this model would be armored at the critical positions, carry powerful cannon armament (2 x 30mm HS.603) with support for aerial rockets (SERAM T-10) to attack ground targets with, and fit the Rolls-Royce "Tay" engine of 7,715lb thrust - and afterburning type - over the original Nene. Nothing came of this venture.

All work on the Espadon aircraft design appears to have ended in mid-1951.

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Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the SNCASO SO.6020 Espadon Assault Fighter-Interceptor Prototype.
1 x Rolls-Royce Nene 100 turbojet engine developing 5,000lb of thrust.
601 mph
967 kph | 522 kts
Max Speed
32,808 ft
10,000 m | 6 miles
Service Ceiling
870 miles
1,400 km | 756 nm
Operational Range
5,300 ft/min
1,615 m/min
City-to-City Ranges
Operational range when compared to distances between major cities (in KM).
The nose-to-tail, wingtip-to-wingtip physical qualities of the SNCASO SO.6020 Espadon Assault Fighter-Interceptor Prototype.
49.2 ft
15.00 m
O/A Length
34.8 ft
(10.60 m)
O/A Width
11.2 ft
(3.40 m)
O/A Height
16,435 lb
(7,455 kg)
Empty Weight
39,198 lb
(17,780 kg)
Design Balance
The three qualities reflected below are altitude, speed, and range. The more full the box, the more balanced the design.
Available supported armament and special-mission equipment featured in the design of the SNCASO SO.6020 Espadon Assault Fighter-Interceptor Prototype .
6 x 20mm Autocannons in nose (three per fuselage side).

Ground attack form was proposed with 2 x 30mm DEFA autocannons and support for SERAM T-10 aerial rockets.
Notable series variants as part of the SNCASO SO.6020 Espadon family line.
SO.6020 "Espadon" - Base Project Designation.
SO.6020-01 - First prototype of 1948; RR Nene 100 engine of 5,000lb thrust; damaged during test flight and reworked to test out wingtip-mounted Turbomeca Marbore turbojets.
SO.6020-02 - Second prototype of 1949 with refinements including flush intakes; reworked to carry SEPR-25 auxiliary rocket booster engine becoming the SO.6026.
SO.6020-03 - Third prototype intended for photo-reconnaissance role with camera-equipped nose; nose reworked and aircraft carried SEPR-25 auxiliary rocket booster becoming the SO.6025.
SO.6021 - Production designation based in SO.6020-03 prototype; lightened structure with larger wings; ejection seat installed; hydraulic-assisted controls; model of 1950.
SO.6025 - Third prototype refinished with SEPR-25 auxiliary rocket engine.
SO.6026 - Second prototype refinished with SEPR-251 auxiliary rocket engine in 1952.
SO.6020 Ground Attacker - Proposed CAS form fitting 2 x 30mm DEFA cannons and carrying SERAM T-10 aerial rockets; powered by RR Tay engine of 7,715lb thrust.
Global customers who have evaluated and/or operated the SNCASO SO.6020 Espadon. Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 4 Units

Contractor(s): SNCASO / Sud-Ouest - France
National flag of France

[ France (cancelled) ]
Relative Max Speed
Hi: 750mph
Lo: 375mph
Aircraft Max Listed Speed (601mph).

Graph Average of 563 MPH.
Era Crossover
Pie graph section
Showcasing Aircraft Era Crossover (if any)
Max Alt Visualization
Small airplane graphic
Production Comparison
Entry compared against Ilyushin IL-2 (military) and Cessna 172 (civilian) total production.
MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030
Aviation Timeline
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Image of the SNCASO SO.6020 Espadon
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Mission Roles
Some designs are single-minded in their approach while others offer a more versatile solution to airborne requirements.
Some designs stand the test of time while others are doomed to never advance beyond the drawing board; let history be their judge.
Going Further...
The SNCASO SO.6020 Espadon Assault Fighter-Interceptor Prototype appears in the following collections:
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