Seafang

Throughout the year of 1946 Air Ministry interest in the Spiteful continued to wane until December when the order was cancelled. As the laminar flow wing was also being used on the Attacker jet fighter for the Royal Navy, test flying continued for a time but all remaining Spiteful aircraft were sold for scrap in July 1948. Although it was obvious that the future lay with jet-powered fighters, the relatively low power of the early jets and their slow response led many to the view that they would be unsuitable for operations from aircraft carriers. The Seafang, a naval equivalent of the Spiteful, had been developed in parallel with the RAF fighter and for a time appeared to have more chances of succeeding. In the event it went the same way as the Spiteful as doubts about operating jet fighters from carriers proved to be somewhat overstated.

The Seafang can be traced back to 7 October 1943 when Supermarine produced Specification 474 for the Type 382 which was a development of the Seafire XV featuring the laminar flow wing and a two-stage Griffon 61 engine. The design was submitted to the Royal Navy and the Ministry of Aircraft Production, but despite an estimated top speed of 488 mph, an initial rate of climb of 4,900 ft/min and a service ceiling of 41,750 ft, at first little interest was shown in the project. Nothing was heard, in fact, until 21 April 1945 when the Air Ministry issued Specification N.5/45 for a single-seat fighter for the Fleet Air Arm, the performance of which closely matched that of Supermarine’s proposal eighteen months before. Two Seafangs (VB893 and VB895) were requested, but with the cancellation of the order for Spitefuls, came an instruction to proceed with the production of the Seafang to utilise, as far as possible, the materials and components that had already been allocated to the Spiteful order. The serial numbers given to this batch were VG471–505, 540–589, 602–650, 664–679.

The first Seafang was in effect a ‘navalized’ Spiteful F.14 (RB520) fitted with a sting-type arrester hook. This aircraft undertook flight trials with Supermarine during the summer of 1945 but it was already becoming evident that the Navy was lukewarm to the Seafang as RB520 remained with the manufacturers after its test schedule had been completed and was not collected by the service until 1947, whereupon it was immediately struck off charge. In the event only one prototype Seafang was to fly (VB895), however, the next to make it into the air was VG471 which had started life as the sixth production Spiteful. As such it had no wing folding mechanism, a five-bladed propeller and was delivered to the RAE at Farnborough in January 1946 as the Seafang F.31. As the first true Seafang, VB895 (designated F.32) was flown for the first time in early 1946. It was powered by a Griffon 89 driving a contra-rotating propeller and featured wing folding, although on the Seafang only the outer portions of the wings were made to fold.

After abortive attempts to interest the Royal Netherlands Navy in the Seafang in August 1946, VB895 was used for deck landing trials on HMS Illustrious on 21 May 1947. These were carried out by Supermarine test pilot Mike Lithgow who had previously completed a series of ADDL’s at Chilbolton and RNAS Ford. Although only eight landings were made on Illustrious, Lithgow was quite happy with the Seafang which proved to be an excellent deck landing aircraft, the best approach speed being 110 mph IAS (95 knots). The view was relatively good and the aircraft settled easily on to the deck with no float when the throttle was cut. The lack of torque from the Griffon 89 and contra-rotating propellers made the aircraft ideally suited to deck operations.

Although the Seafang had shown great promise, it ultimately lost out to the vast potential offered by the jet engine. The development sequence initiated by Frank Whittle with his series of centrifugal jet engines found its ultimate expression in the Rolls-Royce B.41 Nene which was soon offering around 4,500 lbs thrust. As a result of the research already carried out by Supermarine into the laminar flow wing, Joe Smith and his team were asked to come up with a new fighter to Specification E.1/44, an aircraft that was effectively a ‘Jet Spiteful’. As the Supermarine Type 392, it featured laminar flow wings with the radiators removed and additional fuel tanks in their place. Three prototypes were eventually ordered (TS409, 413 and 416) the last two to be ‘navalized’ (but without any form of wing folding) and Specification E.10/44 was soon drafted around the design. Although the E.10/44 (soon to be named Attacker) at first exhibited many of the handling characteristics of the Spiteful/Seafang, it held the prospect of much improved performance and when fitted with a production Nene of 5,000 lbs thrust., it was capable of a maximum speed of 580 mph at sea level. After a comprehensive development programme to improve low speed handling, the first of 145 Attackers for the Fleet Air Arm was taken into the air on 5 April 1950 and the type remained in front-line service until replaced by Sea Hawks and Sea Venoms in 1954.

Despite the disappointment of the Seafang not being ordered by the Royal Navy, it possessed essentially the same wing as the Attacker and was therefore still of value to the Supermarine company. As part of the research effort to obtain data on the laminar flow wing, Seafang F.32 VG475 was fitted with a vertical pitot comb on a mounting behind the starboard wing trailing edge. To facilitate this arrangement aileron span had to be reduced by 15 in and the cannon armament was also removed. A camera installation was fitted in the fuselage in place of the rear fuel tank. John Derry commenced test flights on 23 June 1947 and reported his findings as follows

‘The aircraft was climbed to 27,000 ft and dived to a speed of 400 mph at 20,000 ft. This speed, Mach 0.77, was attained without any noticeable compressibility or other effects. The Mach meter was reading 0.75 and a film was taken. At that moment and with no warning, the most violent pitching set up. This took the form of a high-frequency phugoid and, owing to the large angle of pitch at this frequency, the amount of positive and negative ‘g’ induced was considerable. The Mach meter was still reading 0.75 during this incident. It was found impossible to check the phugoid, which immediately began to diverge rapidly and it was quite impossible to hold the stick steady. The engine was throttled right back immediately, but recovery from the dive could not be attempted owing to the inadvisability of adding more ‘g’ to the already extreme amount to which the aircraft was being subjected at the bottom of each phugoid. Not until 16,000 ft had been reached did the pitching decrease sufficiently to allow a pull out.’

To demonstrate that this particular characteristic was Mach related Derry carried out a dive in the Seafang to 450 mph from 10,000 ft without any undesirable handling effects. Subsequent modifications to the framework holding the pitot comb and the elevator trailing edge allowed dives to be made up to Mach 0.83 in perfect safety. These experiments unfortunately confirmed that the slightest irregularities in wing surface led to the formation of turbulent flow much further forward than was desired. Debris of only 0.020 in on the surface of the wing was likely to lead to loss of laminar flow at around 10 per cent chord with a significant increase in drag.

Further experiments with the Seafang included a servodyne-assisted aileron system which was fitted to VG474 in late 1947. This led to a significant improvement in the rate of roll at cruising speeds but at limit speeds there was hardly any benefit so that the spring-tab ailerons on the Attacker were retained. Seafire F.32 VB895 was also flown with a 170-gallon under-fuselage tank of ‘airship’ type and undertook the service acceptance trials of the four 20 mm Mark V Hispano cannon, the same installation as used on the Attacker. During testing at Boscombe Down an explosion occurred in the port wing after firing which caused a significant amount of damage. It was discovered that this had been caused by a build up of carbon monoxide gas in the gun bay which required the fitment of ventilators above and below the wing. After this modification had been embodied the rest of the air firing trials were completed without further mishap.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s