Editing Dewoitine D.520 (section)

===Additional prototypes===
During 1939, the first prototype was followed by two further examples: the D.520-02 and the 03, these were first flown on 9 January 1939 and 5 May 1939, respectively.<ref name="Danel 4 5">Danel 1971, pp. 4–5.</ref> The major differences between the first prototype and the second and third were the adoption of a new sliding [[Aircraft canopy|canopy]], the fitting of a re-designed and larger tail unit, and longer [[Oleo strut|Oleo]]-manufactured undercarriage legs; they also omitted the [[Handley Page]] [[Leading edge slats|slats]] fitted to the outer wings on 01.<ref>Danel and Cuny 1966, pp. 36–40, 297.</ref><ref name="Danel 4 5"/>

These prototypes were also armed with a single {{cvt|20|mm|3}} [[Hispano-Suiza HS.9]] cannon with the barrel was in a sleeve between the cylinder banks and fired through the propeller spinner.{{#tag:ref|This was a feature introduced by [[Hispano-Suiza]] during the [[World War I|First World War]] and later found on many German designs (as the ''Motorkanone''), as well as on Russian derivatives of the 12Y engine.|group=nb}} and a pair of [[MAC 1934]] {{cvt|7.5|mm|3}} [[machine gun]]s, each initially with 300 rounds per gun, housed in small pods under the wing.<ref name="Danel 4"/> The third prototype also introduced a small tailwheel instead of the original skid. The second prototype was later fitted with a [[Hispano-Suiza 12Y-31]] engine and achieved a maximum speed of {{cvt|550|km/h}} and reached {{cvt|8000|m}} in 12 minutes 53 seconds.<ref name="Car728"/><ref name="Danel 4"/>

In response to [[Belgium|Belgian]] interest in the D.520, who were at one stage preparing to negotiate for a [[Licensed production|licence to produce]] the type, several evaluation flights of the third prototype were flown by Belgian test pilot Captain Arendt.<ref name="Danel 5">Danel 1971, p. 5.</ref> During late September 1939, CEMA took charge of the third prototype to conduct armament trials. Overall, flight tests had proceeded successfully, and resulted in the issuing of a contract in March 1939 for 200 production machines to be powered by the newer -31 engine (later replaced by the -45). A contract for an additional 600 aircraft was issued in June, albeit reduced to 510 in July 1939.<ref>Caruana 1998, pp. 728, 730.</ref>