Prototype aircraft catapult uncovered

Catalupult system

View of the remains of the RAE Mark III aircraft catapult from the early days of the Second World War uncovered at Harwell. © MOLA

During excavations south of the English city of Oxford, archaeologists have unearthed and mapped the remains of a World War II aircraft catapult. The experimental system was intended to propel bombers into the air using a motor-driven compressed air catapult without long runways. However, the catapult system that has now been excavated was never put into operation and was shut down again in 1940 and partially built over. Only now have researchers unearthed the concrete remains of the catapult.

They are still in use on modern aircraft carriers today: special catapults are used to accelerate aircraft and get them into the air even without long runways. To do this, the aircraft are usually hooked into special carriages using hooks, which are accelerated along a rail by high-pressure steam and pull the aircraft along. At the end of the runway, the plane disengages and takes off. The origin of such aircraft catapults goes back to the period between the two world wars. At that time, both the German and British navies experimented with various hydraulic and compressed air-powered catapult systems.

Catapult rail
Harwell aircraft catapult rail. © MOLA

Turntable, compressed air carriage and two runways

Archaeologists from the Museum of London Archeology (MOLA) in Harwell, near the English city of Oxford, have now examined one of these early aircraft catapults in more detail. In advance of construction work, they uncovered and digitally mapped the remains of a catapult system built between 1938 and 1940. “The prototype of this catapult, called the Royal Aircraft Establishment (RAE) Mark III Catapult, was the result of three years of development work,” explain the researchers. The system consisted of a large turntable that could be aligned to two 82 meter long runways.

The aircraft catapult was powered by twelve Rolls-Royce aircraft engines that were located under the turntable and compressed air to 136 times atmospheric pressure. This compressed air was then used to drive a pneumatic carriage to which the pulling hook for the aircraft was attached. “This fascinating structure reminds us of the period of experimentation and rapid innovation in the years between the First and Second World Wars,” explains MOLA’s Susan Porter. “The existence of this facility was known from historical documents. But only now have we been able to document the structure in all its details.”

Forerunner of later ship catapults

Using measurements and hundreds of photos, the archaeologists created a detailed digital 3D reconstruction of the aircraft catapult. It is known from historical records that this catapult prototype was never used due to various technical problems. Among other things, the engines for compressing air kept failing. It also became clear that the design of the system did not fit the aircraft types for which it was actually intended. The engines and the catapult carriage were therefore dismantled as early as 1941. Later, a normal runway was built across the southern arm of the filled-in aircraft catapult.

“Nevertheless, this aircraft catapult paved the way for later launch systems such as the CAM system, which was used to protect merchant ships early in World War II,” MOLA explains. These British cargo ships, known as Catapult Aircraft Merchantman, were poorly equipped with a catapult and a fighter aircraft attached to it to protect them from enemy attacks. However, this aircraft could not land at sea, so the pilot had to parachute out or ditch the aircraft after a mission on the ocean. This is one of the reasons why these CAM catapults were only used in combat missions nine times.

Source: Museum of London Archeology (MOLA)

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