The Science Behind the Spitfire – Part 2: Marvelous Metal
In celebration of British Science Week we continue our exploration of the Science Behind the Spitfire. The aeroplane is renowned for its performance and the important role it played during the Second World War. We will peel back the panels and discover some of the science behind the Spitfire’s success.
Today we will be focusing on the innovative construction of the Spitfire’s all-metal body. But to understand why the materials in the Spitfire were so effective, we need to go back in time a little further…
The world’s earliest aeroplanes were made from wood and fabric and held together with twine. This worked well at first, but as aeroplanes got faster and more sophisticated new materials were called for.
The First World War accelerated aircraft technology and saw some of the first all-metal fighter planes using light, aluminium alloys. These new materials were strong but light, and more durable than wood. Metal could also be easier to shape, build and repair.
More and more aeroplanes began to be built from metal throughout the 1930s, especially as speeds got faster and faster.
Reginald Mitchell and his team at Supermarine had experience of using light, streamlined metal frames and skins from their work with racing seaplanes. It seemed a natural choice for the design of their new fighter.
Do you remember the pesky force of drag from the last blog post? (Trying running into a strong wind!). The curved metal panels that cover the Spitfire’s body helped the air move around it more effectively and reduced drag. The attention to detail even extended to the rivets, which were countersunk to stop them sticking out. This provided a perfectly smooth, streamlined surface.
Strong But Light
The frame of Spitfire was supported by the stressed metal skin (an arrangement known as semi-monocoque). They worked together to make the body of the Spitfire incredibly strong. The metal components were made from alloys of aluminium. This ensured that materials were as light as possible, whilst still providing strength and durability.
Under the skin, four horizontal spars of metal called longerons are connected together by a series of oval frames. These frames reduce in size towards the tail and have round holes cut into them. These holes make them even lighter without weakening them.
In the first Spitfires everything was metal apart from the control surfaces (the flaps on the wings and tail used to steer the aeroplane). However, flying at high speeds could distort the fabric which made the aeroplane harder to control. Later Spitfires, such as the museum’s RW388, had metal-clad control surfaces.
Not all of the metals used in the Spitfire were light aluminium alloys. Certain areas needed extra re-enforcement. Armour plates were installed in areas of the cockpit to try and protect the pilot from enemy fire. They might be effective against machine gun bullets, but were little help against explosive cannon rounds.
So, that’s another bit of Spitfire science ticked off. Join us in a couple of days when we lift the hood to inspect the famed Merlin engine…