Dewoitine D 53

Following the loss, at the end of July 1930, of the first pre-series D 27 as a result of a wing structural failure, a substantially reinforced wing structure was designed to meet new requirements imposed by France's Service Technique. Emile Dewoitine had, at this time, been assured by the Ministere de l'Air of an order for 90 D 27 fighters with reinforced wings, although this was not, in the event, to be confirmed. The structural changes were accompanied by a change in designation from D 27 to D 53, the first reinforced wing being completed on 27 February 1931, and this being applied by Liore-et- Olivier to D 27 No 14 to produce the D 530 which flew at the end of the following month. The D 530 was powered by an Hispano-Suiza 12Md, a lightened version of the HS 12Mb (HS 57) engine of 500hp. The HS 12Md was not acceptable to the STAe, the second, third and fifth D 53 series fighters therefore being fitted with the standard HS 12Mb as D 531s for official evaluation. Weighing 1420kg, these recorded maximum speeds of 269km/h at sea level and 258km/h at 5000m during trials at Villacoublay. In August 1931, the Turkish government expressed interest in the D 53 and was offered versions with either the compressor-equipped Skoda Lr engine of 580hp or the Curtiss V-1570 Conqueror of 600hp. The fourth D 53 series fighter prototype flown in the autumn of 1931 was the D 532 with a compressor-equipped Rolls-Royce Kestrel engine. This attained 313km/h at 4000m, climbing to that altitude in 6.9 min, but excessive oscillation of the tail led to discontinuation of flight testing and re-engining with an HS 12Mb engine as the D 534 LP. Flown in April 1932, the D 535 was equipped with a 500hp HS 12Xbrs engine, this becoming the D 536 when fitted with a Farman compressor which raised the output of the HS 12Xbrs engine to 570hp at 5800m. In July 1933, a twin-float fighter version of the D 535 was offered to Peru, which, in the event, procured Nieuport- Delage 123s. Only seven D 53 series aircraft were flown of which two D 531s allegedly found their way to Republican Spain during the Civil War, becoming known as Dewoitinillos or Dewoitine pequenos (little Dewoitines) to distinguish them from D 371s. The dimensions of the D 53 series were similar to those of the D 27.