Uploaded 05 Jun @ 18:36pm
The Spitfire Heritage Trust has recently completed a major project, successfully building from scratch an exact, full size ‘all fibreglass’ replica of the iconic WWII ‘Battle of Britain’ Supermarine Spitfire Mk VB (Type 359). Designed by Reginald Mitchell, and produced from 1938-1948 at Supermarine Aviation where he was employed as an engineer, the original Spitfire fighter-interceptor was the first all-metal stressed-skin aircraft.
All of the glass reinforced plastic (GRP) aircraft body parts manufactured for this replica were moulded using laminating resins and structural adhesive materials supplied by the project’s principal sponsor Scott Bader
The authentic, GRP replica Spitfire has been specially built in the UK for the Kingdom of Lesotho (formerly Basutoland) in southern Africa by a dedicated team of volunteers from The Spitfire Heritage Trust. The Lesotho replica Spitfire project came about in order to recognise and pay tribute to the generous ‘Gift of War’ given in June 1940 by the people of Basutoland, with a population of only 400,000 at the time. The response to the war funds appeal was overwhelming, raising sufficient money from donations to pay for the manufacture of 24 Spitfires, so providing much needed new fighter-aircraft for two RAF squadrons. From this ‘Gift of War’ donation, No 72 (Basutoland) Squadron was born in 1940 and continues today as an active RAF training squadron.
It was manufactured in Victoria, close to St Austell, Cornwall, using factory space, facilities and GRP expertise provided by Paul Ching, Managing Director of Evolution Boats. As a master mould designer and keen Spitfire enthusiast, he brought invaluable experience to the team having previously built a FRP replica Spitfire IIa for the RAF on permanent display at RAF High Wycombe.
For the new static display replica aircraft, using hand lay-up glass fibre - UPR resin based laminate systems were technically sufficient for moulding the GRP parts. However, there were still a number of technical performance-in-use considerations to ensure the correct choice of laminate system for specific sections of the aircraft to ensure that key areas would have the necessary mechanical and physical properties needed to cope with being exposed long term to the elements. Annual climatic conditions in Maseru, the capital of Lesotho where the Spitfire is on permanent outdoor display, typically have seasonal wet and very dry conditions, high winds, extensive periods of intense sunlight and a range of extremes in the ambient temperature from as low as -10°C at night in winter up to average daytime of 28°C in high summer, with maximum temperatures sometimes exceeding 35°C.
To cope with these conditions, after taking advice from Scott Bader’s technical support team, two different Crystic polyester back-up resin grades were specified. For the wings, given the dark paint colours used to camouflage the upper surface along with prolonged periods in direct sunlight and high ambient temperatures, ensuring the wing sections maintained stiffness, did not warp or twist, and could support their own weight, Crystic 489PA isophthalic unsaturated polyester (UP) resin was specified due to its elevated temperature performance. In addition to the upper and lower GRP wing sections and inner cross stays, the inner ‘I’ beam shaped GRP main spars (one for each wing) which run the length of the wing and fit into a rectangular ‘carry-through’ tube through the lower fuselage section in front of the cockpit, were also laminated using glass reinforced Crystic 489PA resin on the primary structural bulkhead immediately after the engine nose section.
For the main fuselage sections and the tail, Crystic 2.414PA, a low styrene, low exotherm, rapid hardening orthophthalic resin was recommended, being an easy to use, high productivity hand lay-up laminating resin.
Further reading: www.scottbader.com
Ben Hayes – Sales Manager, CWST
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