Back to the Drawing Board: The Supermarine Nighthawk

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David Porter on military history’s doomed inventions

The first Zeppelin raids on Britain in 1915 inflicted no more than minor damage, but provoked a massive public outcry demanding aircraft capable of intercepting the airships.

One of the oddest inventions was the Supermarine Nighthawk, a massive twin-engine quadruplane night fighter designed to fly patrols of anything up to 18 hours at a time, with a fully-enclosed heated cockpit and even a small sleeping berth.

The Supermarine Nighthawk. Its weight was the main obstacle to success.
The Supermarine Nighthawk. Its weight was the main obstacle to success.

At first glance, it seemed formidable – its armament was exceptionally heavy by contemporary standards, comprising a 2-pdr (40mm) Davis recoilless gun in a mounting firing over the top wing plus two .303in (7.7mm) Lewis guns, one behind and just below the Davis gun, the other in the nose.

(The Davis gun had been invented by Commander Cleland Davis, USN, in 1910. It had a breech that was open to the rear and used the counterweight principle, in which the cartridge fired a weight – lead shot packed in grease – to the rear that was equal to the projectile weight, cancelling out the recoil.)

According to some reports, stowage was also included for a number of light anti-Zeppelin incendiary bombs. A small trainable searchlight powered by an auxiliary motor was mounted in the nose to illuminate targets.

Weight and drag

The weight of all this equipment and weaponry, combined with the drag of the forest of struts and bracing wires, meant that the engines of 1916/17 simply did not have the power to give the Nighthawk a reasonable performance.

Supermarine’s design team used two 100hp Anzani radial engines, which they calculated should give a top speed of at least 75mph (121km/h). Unfortunately, this proved to be grossly optimistic, and the prototype, which first flew in February 1917, struggled to reach 60mph (97km/h) at 6,500ft (2,000 metres). The rate of climb was equally abysmal – it took an hour to reach 10,000ft (3,000 metres)!

This speed was barely equal to that of the Zeppelins, and it seems unlikely that the Nighthawk could have reached its service ceiling of 13,000ft (4,000 metres). Even if an interception had been made, there would have been problems – the Davis gun was very light, but its cartridge cases were huge, as recoilless guns required a very large propelling charge, whilst reloading was cumbersome and slow.

The procedure was to unlock the two halves of the gun, then pull the rear half backwards before rotating it to clear the breech, extract the fired cartridge, and finally reload. This meant that the chances of getting a second shot at the target were remote.

But there was another problem, as the gunner had to remember that counterweight – if he fired upwards, there was a real risk of it blowing a large hole in the aircraft. (A shot forwards and upwards was also likely to be fatal for the Lewis gunner just behind him!)

It rapidly became apparent that the Nighthawk could never be a successful night fighter, and the prototype was scrapped in October 1917. Perhaps the only good thing about the project was that it showed one member of the Supermarine team ‘how not to do it’ – that young man was R J Mitchell, who went on to design the Spitfire.

This article was published in the March 2020 issue of Military History Matters. To find out more about subscribing to the magazine, click here.

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