How realistic are Dunkirk's Spitfire flight scenes?

Is the climactic end to Christoper Nolan's blockbuster true to physics? (Spoiler alert)

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If you took Nigel Farage's advice and went to see Christopher Nolan’s latest epic Dunkirk, you may have left with a few questions. Like, does Farage care about the film's failure to represent the contribution of the Royal Indian Army and accusations of whitewashing? How big a Harry Styles fan is he truly? Did he stream the star's debut solo album, or does he just weep when "Sign of The Times" comes on the radio? Or perhaps you're mulling the question that’s plagued my mind since seeing it - how true to life are those flight scenes?

Nolan films three Spitfires in the air, two of which are Mark 1s, whereas the third one is a Mark 5. While Mark 1s were used at Dunkirk, it would be a few years until the Mark 5s joined the war effort. Debates about historical accuracy aside, this isn’t an oversight worth fighting your friends about.

The small fuel tanks used by the Spitfires provide the film with a major plot point. The Mark 1s had a flight time of just two and a half hours. Why weren’t these planes designed to carry more fuel? They were designed to just get over the channel and then refuel in France. However, by the time Dunkirk was taking place, the RAF squadrons had already retreated to England. Spitfire pilots therefore, as seen in the film, had to conserve as much fuel as possible in order to be able to return home. 

The really burning question on every movie-goer’s mind probably concerns whether Tom Hardy’s plane could really pull off the extended engine-less glide near the climax of the film. Hardy’s eyes, which as the only part of him seen for most of the film may soon be Oscar nominated, surely cannot keep a plane in the air for so long through the power of charisma alone?

The answer to whether that glide really is feasible is, as is often the case, yes and no. The official pilot notes for the Mark 1 indicate that spitfires can achieve "long distance gliding", but only if the plane is travelling at around 120 miles an hour before the engine cuts out. If the plane is travelling too fast before the engine stops turning the rotors it will spin out of control. If it is going too slowly it won’t glide very far. The distance travelled is also dependent on how flat and straight the descent is.

There aren’t many real life examples of Spitfires gliding without engines, but Martin Bowman’s book RAF Pilots in WWII does note a Spitfire pilot who glided for over 15 miles with a damaged engine. The beaches of Dunkirk are just over 10 miles long so in theory Hardy could have made it all the way along the beach's length without his engines..

But at the film's climax, not only does Hardy glide, he also manages to turn the plane and come in for another run to shoot down a German Stuka. Hardy’s heroics and Nolan’s climax, while powerful (what are the odds Farage shed a tear during this scene?) play loose with the laws of physics (Farage definitely cried). The spitfire would have been travelling at around 100 miles an hour for it to turn as Hardy did and the Stuka he has to catch up with would have been doing about 400 miles an hour in a dive. And of course the Stuka would probably have seen Hardy’s slow-gliding spitfire miles away.

This is all before you even consider the scarily low altitude Hardy was flying at just metres above the beach. A turn like the one he made could have had horrendous consequences for the men below - which wouldn’t have made quite such a rousing end to the film.

Much like Farage himself, Nolan took more than a few liberties with the truth in order to spin a good story.