The Whif bit ...
North American and the 'Simplified Spitfire'
Although the Air Ministry was already issuing Specifications for Spitfire replacements, it was understood that these Specs would not bear fruit for some time. By way of challenge, 'Dutch' Kindelberger was asked whether his firm was capable of designing a 'Simplified Spitfire' for the interim. Kindelberger was confident that North American Aviation could indeed devise a 'Simplified Spitfire' in the short term. Discussion then turned to the specifics of such a design.
In the minds of Air Ministry staff, any 'Simplified Spitfire' would need a great deal of commonality with existing service Spitfire Mk.I fighters. This included the 1,030 hp Rolls-Royce Merlin III engine and its DH constant-speed propeller. The cockpit and radio installations must also be unchanged. [1] Armament was also to be unchanged, consisting of eight .303-inch Browning machine guns with a minimum of 300 rounds per gun. General performance was to at least match that of a Supermarine-built Spitfire Mk.I. No other firm requirements were made but value would be assigned to the use of as many standard Spitfire components as possible.
With an agreement in place for the design of an experimental 'Simplified Spitfire', Kindelberger booked passage home to Los Angeles. Long-distance telephone calls had already set the design wheels in motion. Ed Schmued was assigned the task of drafting a design that would allow a Spitfire development to be built at the speeds Kindelberger had witnessed in Germany (and knew that NAA was quite capable of). Rough design work was begun while 'Dutch' returned home with cases of Spitfire drawings copied on microfilm. But, unbeknownst to Kindelberger or Schmued, an even greater gift would soon arrive at the NAA offices at Mines Field, Los Angeles.
In August 1938, 19 Sqn RAF received Spitfire Mk.I K9792 (c/n 6) for operational use from RAF Duxford, Cambridgeshire. Just over a month later, K9792 would be written-off when it flipped over in a landing accident. After damage assessment, the wings, rudder, and cowl was removed for scrapping. The slightly-damaged fuselage was then crated for shipment to NAA where it was to act as a partial pattern airframe. Accompanying K9792 was a sample DH airscrew (to replace the non-running Merlin II's damaged wooden 2-blader). No repair work was undertaken before shipment to the US.
NA-53M - A 'Simplified Spitfire' Takes Shape
By the time that K9792 arrived at San Pedro Bay, work had began on replacement wings. In its crash, K9792's bottom longerons had been distorted by impact around its wing mounting points. This proved a moot point as Ed Schmued had already decided to replace Supermarine's 'bolt-on' separate wing panel approach. Instead, the uninterrupted, one-piece wing design from the 'Super NA-50' and P.509 projects was to be adapted to the Spitfire. To that end, the damaged portions and much of the rest of K9792's lower fuselage was removed. The intention was to allow quicker assembly and attachment of both wings and a new belly radiator bath (also adapted from the P.509).
Top Ex-K9792 acting as an engineering mock-up for the NA-53M. [2] Note new wing cut-out and belly radiator scoop. The damaged Spitfire vertical tail later formed the basis for a wooden NA-53M tailplane mock-up. [3]
Forming a working mock-up and acting as a prototype of sorts, the revised K9792 would never fly again. Instead, the first 'Simplified Spitfire' to fly was the first production airframe, NA330, which incorporated a number of components raided from K9792 to speed the assembly process. Such was the urgency assigned to the type, that it was ordered into production off the drawing board. Before NA330 was rolled out of NAA's plant at LA in December 1939, the British Purchasing Commission had already order 200 new fighters for the RAF under the name North American Nemesis Mk.I.
Bottom The first North American Aviation NA-53M Nemesis, NA330. This aircraft was flown in full RAF markings (note small US civil experimental registration 'NX-330F' marked below the horizontal tail surfaces).
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[1] This meaning the bulged Perspex sliding hood and exterior armour-glass windscreen installation as well as mountings for an HF TR9 R/T set (with allowance for future VHF T/R Type 1133 installation).
[2] For unrecorded reasons, the North American Aviation drawing office regarded the 'Simplified Spitfire' as a continuation of their NA-53 sequence. Accordingly, the redesign was assigned the NAA 'Charge Account' number NA-53M (for Merlin).
[3] The NA-53M's squared-off horizontal tails were never applied to the engineering mock-up. When the mock-up was stripped to provide components, hatches, etc. for NA330, the stabilizers and elevators were removed from ex-K9792 for return to the UK.
