Sud-Est SE.2410 Grognard – The Hunchback Plane
The SNCASE Grognard was a French experimental fighter and ground attack aircraft developed in 1950. The aircraft was designed by SNCASE (Société Nationale de Constructions Aéronautiques du Sud-Est) also known as Sud-Est as a jet aircraft capable of carrying out lower-level ground strike manoeuvres.
The Grognard was developed as part of a wider scheme to revive the French aircraft industry and expand the French Air Force’s fleet in the aftermath of the Second World War.
The SE.2410 used highly innovative and unusual design features to meet the needs of the French Air Ministry. Emphasis was placed on the plane’s speed and aerodynamics. However, its abilities were called into question when the Air Ministry changed its specification requirements and delays prompted a loss of interest in the project.
Despite the designers and engineers tinkering with the design, the Grognard never entered mass production and remained in the experimental phase with only two examples being built.
In the aftermath of the Second World War, there was a concern in France that the country was falling behind other nations in the aviation and technology sectors.
French aircraft designing had been done quietly during the war, but the actual production stages had been effectively halted or were tightly regulated by the Germans during the Nazi occupation of the country, with German military officials confiscating some finished French aircraft concepts.
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In 1941, a collection of major aircraft companies in France were merged to form Sud-Est which was also known by the acronym SNCASO (Societe Nationale des Constructions Aeronautiques du Sud-Ouest).
This would later be merged with SNCAO (Societe Nationale des Constructions Aeronautiques de l’Ouest), also an amalgamation of different French aircraft builders.
SNCAO’s assets were merged into SNCASO during the war and the name remained until SNCASO was merged into another conglomerate, the SNCASE (“Societe Nationale de Constructions Aeronautiques de Sud-Est”) to form Sud Aviation.
Once the German occupied was over and the war was finished in 1945, the French government sought to revive domestic aircraft manufacturing for both military and commercial planes.
As part of this, the French Air Ministry issued a specification for a new jet-powered strike and attack aircraft in 1948. The new aircraft must have the capability to fly fast but low, evading enemy radar or ground defenses before reaching the target.
As luck would have it for Sud-Est, engineers at its SNCASO predecessor had begun working on a design in 1945 for an aerodynamic strike and fighter aircraft. Sud Aviation gathered what the SNCASO engineers had drafted and continued working on the design to meet the government’s specification call.
The engineers sought to make the aircraft as aerodynamic as possible and explored different options that differed from conventional designs that French manufacturers had previously built.
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To achieve this, they opted for an unusual “stacked” design which overlapped parts of the fuselage, engine intakes and cockpit over each other.
Although it resulted in a bulbous-looking plane, with the designers unceremoniously nicknaming it the “Hunchback,” it was intended to maximise space within the plane and that even in the event of one engine failing, the jet’s aerodynamic qualities and thrust symmetry would keep it flying for a substantial distance.
A single, streamlined air intake for the engines was fitted behind the cockpit and a split thrust exhaust was placed at the back.
After researching various wing ideas, the engineers decided to sweep the wings back at 47 degrees. A horizontal stabilizer was mounted low on the tail so as not to impact the airflow coming from the front of the plane.
The plane also did away with traditional stick or yolk controls and instead sought to utilize elbow controls to give the pilot more forward visibility.
The cockpit was also set towards the front of the fuselage and despite the advanced features of the prototype, Sud-Est unusually chose to fit a greenhouse canopy to the plane, a feature which had been more common on planes at the start of the war rather than after.
Sud-Est gave the new prototype the provisional name SE.2400 and submitted it for wind tunnel tests. The wind tunnel found that the plane’s unusual design features showed promise and were considered an improvement on previous aircraft designs which had suffered from drag or aerodynamic issues. Certain issues were detected in the flaps and ailerons which prompted Sud-Est to refine the concept and build two more models with modified flaps.
Finally, a tricycle undercarriage was fitted.
The new plane was subsequently named the “Grognard” (French for Grumbler) as a reference to the nickname given to soldiers in Napoleon’s elite old guard.
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For the flying prototype, the engine unit would consist of two Rolls Royce Nene turbojets built under licence by Hispano Suiza. Each engine unit could produce up to 5,000 pounds worth of thrust and yield a projected top speed of 645 miles per hour. The predicted range for the jet was around 530 miles and it would have a climb ceiling of 38,050 feet.
The design continued to evolve with various concepts known as the Grognard II designed for a two-man crew. The Grognard II also featured an updated radar system and a stretched fuselage. The old-style greenhouse canopy was also swapped for a more modern bubble design to ensure a more streamlined effect.
All variants of the Grognard were designed without pressurized cockpits as it was assumed the jet would perform low-level sorties against attack targets on the ground beneath radar or surface-to-air missile range.
Although neither of the prototypes was fitted with weapons, the designers intended that production model Grognards would be armed with two French-made DEFA 30 mm canons in the nose while a bomb bay would be fitted beneath. The wings would have space for guided or unguided bombs, rockets and missiles either made by French weapons company Matra or American-built rockets from HVAR.
Although the Grognard had been developed in secret by Sud-Est during its initial stages, an early smaller-scale model was first shown to the public at the 1949 Paris Air Show to showcase new French jet development followed by a full-scale prototype at the 1953 Paris Air Show.
The French Air Force submitted order plans for a fleet of 360 Grognard strike jets as part of its fleet expansion and post-war reconstruction plans.
The working Grognard I prototype completed its maiden flight on the 30th of April 1950 at a French military base. The Grognard II followed with its maiden flight on the 14th of February 1951.
Although both prototypes generally met expectations and their unusual features showed as much potential in the air as they had in the wind tunnel, the Grognard II was found to have potentially problematic vibration issues in its tail which had to be addressed by the designers.
However, during the production delays brought on by the tail modifications, the French Air Force began to lose interest in the project.
As the Grognard was being tested, the French Air Ministry had since altered their requirements for new fighter aircraft that essentially eliminated the need for low-level ground attack jet aircraft. They instead called for manufacturers to focus on fast fighter and higher-altitude bomber planes.
The lack of cockpit pressurization hampered the selling point of the Grognard compared to high-altitude jets which were pressurized and the French Air Force opted to go with different designs instead, predicting that further modifications to the Grognard would stall the project further and stymy expansion plans.
The ground attack role was taken over by another Sud-Est produced design, the Vautour, which was favoured by the French Air Force for its more modern and flexible design, and no more Grognard units were ordered for production.
The engineers at Sud-Est debated trying to improve the Grognard’s design by taking the basic concept such as the swept wings but adding modifications to make a more saleable fighter variant.
The proposed design was given the provisional name SE.2418. Ideas for the SE.2418 included upgrading the engines to the newer and more powerful Rolls Royce Tay and incorporating all-weather capabilities into the design. Armament would have again consisted of two 33mm guns installed in the nose. Ultimately came to nothing with the entire Grognard project being officially cancelled in 1952.
Compared to the Vautour, the Grognard’s performance was not considered as strong during testing and the airframe proved unfit for any role other than ground attack limiting any combat flexibility it could have otherwise performed.
Despite this, the Grognard continued to perform useful experimental roles for the French Air Force and achieved firsts in this capacity. Both Grognard models were used as platforms to test new air-to-air missiles and became the first French-built aircraft to fire such a weapon when they were used as testbeds for the Matra T-10 missile.
Unfortunately, the Grognard also met its final end during its use as a test aircraft. During a test flight of the Grognard II, the pilot was given a false alarm when the on board fire warning was triggered.
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The pilot survived after performing an emergency crash landing on the aircraft’s belly, but the Grognard II’s airframe was severely damaged and the plane was written off. The remains of the airframe were salvaged and used by the French Air Force as target practice before it was scrapped.
The Grognard I was used as a target tug before also being stripped down and used as target practice and was sadly scrapped in 1954.
- Crew: 1
- Length: 51 ft 6 in (15.4 m)
- Wingspan: 45 ft 6 in (13.57 m)
- Height: 17 ft 0 in (5.18 m)
- Max takeoff weight: 31,925 lb (14,481 kg)
- Powerplant: 2 × Rolls-Royce Nene 101 turbojet, 4,940 lbf (21.97 kN) thrust each
- Maximum speed: 645 mph (1,038 km/h, 560 kn)
- Combat range: 530 mi (853 km, 460 nmi)
- Service ceiling: 38,050 ft (11,590 m)