Arsenal-Delanne 10-C2

The Arsenal-Delanne 10-C2 two-seat fighter designed by Maurice Delanne and built by the Arsenal de l'Aeronautique was of so-called Nenadovich biplane configuration, the tandem-mounted wings providing a continuous
slot effect and offering exceptional CG travel.

Of metal stressed-skin construction and powered by an 860hp Hispano-Suiza 12Ycrs 12-cylinder liquid-cooled
engine, the Arsenal-Delanne 10-C2 prototype was virtually complete at Villacoublay when German forces occupied the factory in June 1940, work on the aircraft continuing in a desultory fashion and the first flight test being made in October 1941.

After completion of the initial test programme, the aircraft was ferried to Germany for further trials.

The intended armament comprised an engine-mounted 20mm Hispano-Suiza cannon, two wing-mounted 7.5mm MAC 1934
machine guns and two further 7.5mm weapons on a flexible mounting.

The Arsenal-Delanne 10 C2

In the second half of the 30s, the French aerial project engineer Maurice Delanne – just like his colleague Roland Payen – was a hot apologist of an untypical tandem biplane layout (this kind of airplane in French or Russian sometimes is called „Nenadovich“, after the surname of the first proposer of this kind of plane).

This layout depends on two big carrying surfaces of almost equal size, to be placed in some distance along the fuselage, requiring much more bow- than tail-heavyness.

Such laying of the wings makes the front wing something like an „offensive slot“ for the back wing, thus boosting the carrying power of the back wing. Due to this solution, the maximum speed diminishes (but so does also the minimum landing speed), and besides this, the site of the gravity center of the aircraft increases.

The turning and steering capabilities of the aircraft should also undergo corrections.

The first attempt of a practical realization of this idea was the small experimental aircraft Delanne 20, built by Maurice Delanne in the firm Société Anonyme Française de Recherches Aéronautiques (SAFRA).

It was a one-seat one-engined airplane of mixed construction with solid undercarriage, driven by a six-cylinder engine Régnier R6, delivering 180 hp.

However, the aircraft wrecked up during the first start on August 10th, 1938, due to the reason of observable pilotage differences relatively to an aircraft of classical layout.

The second, two-seated prototype, the Delanne 20T, underwent test flights from March 1939 and confirmed the theoretical foundation of the project engineers completely.

The aircraft Delanne 20 excited the French Ministére de l'Air very much, which in the latter half of 1939 entrusted the firm Arsenal de l'Aéronautique in Villacoublay to begin a strict cooperation with Maurice Delanne, for to construct a fighter aircraft of similar aerodynamic layout.

The new machine, named Arsenal-Delanne 10, was two-seated.

Pilot and rear gunner sat in a common cabin at the end of the fuselage, over the rear wing.

Due to this position, the gunner had a position of unimpeded visibility, because nothing stood in his sight.

The worst was the forward view of the pilot, hampered by the long front fuselage and the front wing in form of the letter M.

This wing went overhead and its weight was held by lean struts.

However, the back wing was cantilever and fixed to the lower fuselage.

On the ends of this wing, vertical stabilizer fins of characteristic rounded-triangle outline were mounted.

In the forepart of the fuselage, a Hispano-Suiza 12Ycrs 12-cylinder engine was installed, driving a three-blade
propeller.

The inflow of air for the liquid-cooler was very narrow and had the form of the letter U.

On the flanks of the fuselage, a classical three-point undercarriage was fitted, covered even in released position.

The technology of the structure was also completely new, called „metal translation“.

The covering shell was executed as thin smooth metal sheet from two connected duraluminium coats, linked
together by ripples in the metal.

This cover was very firm and did not need internal reinforcements.

This construction connected the individual covers punctually with the carrying construction.

The first prototype of the two-seater Arsenal-Delanne 10C2 was finished without arming to be installed in June 1940, but saw no flight testings before Guderian´s tanks entered Villacoublay.

However, Luftwaffe officers, obliged with allocating French aviation units for indemnyfing the Wehrmacht and gathering trophies, recommended the RLM to finish the preparation of the fast fighter and to continue the work over this curious aircraft.

But it became summer 1941, when the first circle flight test was possible.

As result, the vertical stabilizers had to be increased. Ultimately, the prototype appears in German colours – in
October 1941 already one year has passed – and managed a second flight without problems and retracted undercarriage.

All in all, the prototype 10C2 executed 15 test flights with an overall time of 6 hours.

Then, the machine was transported to Germany, and the further fate is not known.

The exact results of the tests were not recorded, neither were measurements of performance.

It is not known, how the Arsenal 10C2 had performed in combat conditions.

Probably, it had been necessary to change the engine to the soundest and intensify the armament as well.

Perhaps, other changes were indispensable – e.g. for correcting the pilot´s visibility.

The design concepts promoted by Delanne and also by Payen found no employment on the widest scale.

Indeed, an experimental copy of the aircraft was built in Great Britain by an added back wing of the linker aircraft Westland Lysander, with a gun turret at the end of the fuselage, but attempts were not continued.

A firm that also dealt with the tandem biplane layout was Miles Aircraft Ltd., building the fighter dummy M.35 and the two-engined bomber M.39B.

However, the biggest tandem design in France was Delanne´s bomber DL-150, having a projected range of 2.500 km with a bomb load of 2.400 kg and a speed of 500 kph.

It was not built before the war broke out.

Literature:

1. Letectvi + Kosmonautika nr 23/93

2. Skrzydlata Polska nr 39/84

3. V. Nemecek "Vojenska letadla", d.2, Nase Vojsko, Praha, 1990

4. W. Green, G. Swanborough "The Complete Book of Fighters", Smithmark, New York, 1994