Hi
Stressed skin (metal covered) wings started to replace the earlier fabric covered wings on the Hurricane on the production line during the first part of 1939.
Second part of the year for production Hurricanes.
Putting Hurricane I changes into the one list. First order 600 L serials, second order 300 N serials, third order 1,000 P serials split 500 Gloster, 500 Hawker, with the Hawker section gaining another 24 P, R and W serials as replacements for foreign orders.
Hawker:
61st aircraft L1607 first factory fitted ventral spine (Unconfirmed), taken on charge 6 July 1938.
331st aircraft L1877 fitted with Metal wings for development, taken on charge 16 March 1939
363rd aircraft L1909 first factory fitted Merlin III, taken on charge 20 April 1939
434th aircraft L1980 first factory fitted two pitch propeller, taken on charge 12 June 1939
480th aircraft L2026, marked metal wing, Rotol propeller, development, built in July 1939, taken on charge 28 October 1939
481st and 482nd aircraft L2027, L2028 marked metal wing, both taken on charge 20 July 1939, L2027, L2028, L2039, L2045, L2046, L2047, L2055, L2058, L2065, L2066, L2067, L2068, L2077, L2078, L2079 marked metal wing (July/August 1939)
668th aircraft N2397 and subsequent fitted with TR1133, taken on charge 9 November 1939
685th aircraft N2426 marked as last aircraft of the order with fabric wings, taken on charge 14 November 1939, but see below
901st aircraft P3265 and subsequent fitted with Rotol propellers except for at least one batch meant for tropical service which retained the two pitch DH propellers, P3265 was for development, built in February 1940 but not officially taken on charge until 31 May 1940.
June/July 1940 Hurricane I built with fabric wings at Brooklands P3714 to P3717, P3737 to P3739, P3755, P3757 to P3761, P3767, P3768, P3770 to P3774, P3854, P3858 to P3869, P3872 to P3875, P3882 to P3890, P3897 to P9303, P8809, P8810, P8816 to P8818, R2680, R2681, V7200 to V7209, V7222, V7224 to V7235, V7276, V7281. Total 85 aircraft.
The Ministry of Aircraft Production Price Books indicate the 300 N serials were 35 Fabric wing, 253 metal wing, 12 sold to other customers (Yugoslavia, last 12 serials so expected to be metal wings) The metal wings cost £1,210 the fabric ones £1,008. N2426 is the 85th of the N serials batch meaning 35 out of the first 84 had fabric wings. If you go by taken on charge dates it was part of a group of 5 taken on charge 14 November 1939, the 57th to 61st N serials to do so.
A further complication is the 20 aircraft N2318 to N2337 were the first built at Langley, some had fabric wings, delivered from October 1939 to January 1940, time wise lagging behind later serial deliveries from Brooklands.
It appears from L2026 (480th aircraft) to N2426 (685th aircraft) there was probably an increasing percentage of metal wing Hurricanes built.
Gloster production started in October 1939 with Merlin III, two pitch propeller, metal wing, the 100th built, P2681 and subsequent fitted with TR1133 radio, the 101st built, P2682 and subsequent fitted with a Rotol propeller, P2681 and P2682 taken on charge 27 February 1940
Date wise production starts in December 1937 with Merlin II, fixed pitch propeller and fabric wings, Merlin III from April 1939, De Havilland two pitch from June, a mixture of fabric and metal wings July to November except a handful of possible laggards from Langley, from then on metal wings except the mid 1940 batch, mid November 1939 (Hawker) and late February 1940 (Gloster) change over to TR1133, late February 1940 change over to Rotol propeller.
Sold to Glosters for Finland: N2322, N2323, N2324, N2325 (damaged en route, returned to RAF), N2327, N2347 (crashed in Norway), N2348, N2350, N2358, N2392, N2393, N2394, N2395
Two different draft passages trying to say much the same thing on metal wings from the Hurricane Biography, AVIA 46/114.
As regards the second difficulty, that of the stressed skin all metal wing (File No. 522507/36), the prototype had fabric wings, but it had always been hoped that production aircraft would have the new stressed skin wings. In these wings the metal covering was made a part of the weight bearing aerial structure. The importance if the stressed skin lay in its weight saving capacity. Fabric covered wings had already reached the limit of weight allowed and the stressed skin wings saved no less than 70 pounds. Investigations by the firms into this question had been started as early as July 1935. When the production specification was drawn up however it was decided that the Hurricane should in the first place be fitted with fabric covered wings, which would be interchangeable with metal ones. At this stage the technical state of the stressed skin wings was still experimental and not progressed further than the design stage. The position was aggravated by the fact that Hawkers were working on two other monoplanes for the Air Ministry at the same time, the P.4/34 [Henley] and the F.9/35 [Hotspur], both of which were expected to have metal wings. The construction was the same in each case, the difference being in the armament. In June 1936 it was estimated that the test wing would be ready by September but "stiffness" problems arose which involved a new design and it was necessary to earmark a special group of men in the drawing office for metal wing development. In December it was agreed that the P.4/34 should be fitted with the first pair of metal wings. This decision naturally reacted adversely on the Hurricane and in October 1937 it was considered that the new wings could not come in before the 301st aircraft. It was not until March 1939 that the first pair of production stressed skin wings were received from Glosters and fitted to production aircraft at Brooklands. Shortly afterwards flight tests were completed and the wings were cleared for operational use.
Although the prototype had fabric covered wings it had always been hoped that production aircraft would all have the new stressed skin wings in which metal covering was made part of the weight bearing structure, but when the production specification was being drawn up after the first order, it was evident that the first place Hurricanes would have to be produced with fabric covered wings, which would be interchangeable with the metal ones. At that moment it could not be laid down exactly how many Hurricanes would have to be fitted with the fabric wings for the technical state of the stressed skin wings was still highly experimental and had not progressed further than the design stage. Hawkers were working on two other monoplanes for the Air Ministry, the P.4/34 [Henley] and the F.9/35 [Hotspur], both of which were expected to have metal wings and the question of which type should have priority was a difficult one. In June 1936 the R.T.O. had judged that the test wing would be ready by September and the first pair of wings ready for fitting to an aircraft in March. Later "stiffness" problems arose which involved a redesign to combat the delay which was inevitable it was necessary to earmark a special group of men in Hawker's Drawing Office for metal wing development and by October it was thought that the first tentative troublesome design stage was over. In December the question of priority had to be finally dealt with and the prototype P.4/34 was chosen for the fitment of the first pair of metal wings, somewhat naturally to the detriment of the Hurricane stressed skin wing development. As might be expected, this meant the definite postponement of production aircraft changing over to the new wings for some time and in October 1937 it was thought that the new wings could not come in before the 301st aircraft. In March 1939 the first pair of production stressed skin wings were received from Glosters and fitted to production aircraft at L1877 Brooklands. Shortly afterwards flight tests were completed and the wings were cleared for operational use. The fact that Glosters had been subcontracted to build the wings, however, probably increased the delay for Mr. Lemon in his famous report of September 1938 (EPM 120 (38)) complained that the production situation at the Gloster Company was quite one of the worst in the entire industry and the order for Hurricane wings was suffering as a consequence.