Flight, December 1938

The Paris Aero Show

A Tandem Tricycle

   Fokker has the only "novelty"’ in the show, a tandem-engined single-seater fighter with a tricycle undercarriage. It may be remembered that a few weeks ago Flight published a scale drawing of a design which a French constructor, Albert, put up to the French Air Ministry two or three years ago. Except for the tricycle undercarriage the general conception was the same. And, incidentally, the Fokker F.23 provides a good demonstration of the price one has to pay for the nose-wheel in the matter of extra weight and bracing, and the loss of internal stowage space by reason of the retracted nose-wheel. In the Albert design the idea was to have a shell-gun in the pusher engine so that the pilot could fire at his adversary when turning away after having delivered the attack with the front guns.
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MILITARY TYPES REVIEWED

Fighters

   MOST unorthodox and interesting of the new Continental single-seater fighters is the Fokker D.23 twin-engined monoplane which at first sight suggests derivation from the G.I or Faucheur two-seater shown last year. Actually the machine resembles the G.I only in the method of carrying the tail on two booms.
   An essential factor governing the layout was the provision of a good field of view for the pilot, who is located forward of the leading edge with one inverted Walter Sagitta in front and a second behind him driving a pusher airscrew. Thanks to the tricycle undercarriage the view while taxying is rather better than from most modern single-seaters.
   Although the internal wing structure is not visible it is of interest because it departs from the standard Fokker methods, being all-metal with duralumin spars, ribs and covering. The fuselage or nacelle is of welded steel tubes and has integral engine mountings; it is covered with detachable duralumin and aluminium panels. The tail booms are of stressed duralumin construction.
   Being sandwiched between two engines, the pilot is afforded a good measure of protection from enemy fire and his safety is further ensured by armour plating to the front and rear of his seat, just above the engines. Additional plates alongside the cockpit guard against lateral fire.
   Each of the three wheels of the undercarriage is of the Argus type with an Olaer strut. The main wheels retract inwardly and the nose wheel in a rearward sense.
   The particular Sagittas fitted are of the I.S.R. type giving 528 h.p. each at 13,400ft. The forward engine is cooled in a normal fashion, but the cooling air for the rear one enters through a scoop under the fuselage. Three-bladed fully feathering V.D.M. airscrews are fitted and the engines are supplied with a Garrelli compressed-air starting system. The fuel tank is installed in the fuselage and has a capacity of 88 gallons.
   Four fixed guns are fitted, two in the fuselage and two in the wing. The fuselage guns are Browning-F.N.s of 7.9 mm. calibre each, firing at the rate of 1,300 rounds a minute. The wing guns are of the same manufacture but of 13.2 mm. bore and with a rate of fire of 1,000 rounds a minute. For these guns a special explosive bullet has been introduced. This explodes 8 seconds after being fired. An interesting development noted in the fuselage is the circular cartridge conveyer.
   The D.23 has not yet been flown and no performance figures are being issued, though a figure of about 330 m.p.h. was being commonly quoted.
   In spite of its advanced design the new Fokker can hardly be such a formidable weapon as the Hurricane and Spitfire shown nearby on the Hawker-Siddeley and Royal Air Force stand respectively.
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