Messerschmitt Bf 109 (1940): the most-built fighter ever

1940·642 km/h·33,984·DB 605A inverted V-12, 1,475 PS·660 km (E) · up to 1,994 km with tank (G)·12,000 m

· THE STORY

The fighter everything was measured against

The Bf 109 was the smallest airframe that could be wrapped around the biggest engine available, and Germany built some 34,000 of them — more than any other fighter in history. Over England in 1940 it was at least the equal of the Spitfire: it climbed better, dived better, and its engine kept running when the Spitfire’s cut out. What it did not have was fuel. Flying from France, a 109 had perhaps ten minutes of combat over London before it had to turn for home, and that, not any fault in the aircraft, lost the battle.

642 km/hTop speed (G-6)33,984Built

· WHY IT MATTERED

Injection beat the carburettor

Push the nose down hard and the fuel in a float carburettor floats to the top of its chamber: the engine starves, then floods. Merlin-engined Spitfires and Hurricanes lost power for a second or two whenever a 109 bunted into a dive, because the DB 601 injected fuel straight into its cylinders and did not care which way was up. The RAF’s first fix, in 1941, was a brass restrictor designed by Beatrice Shilling at Farnborough; the real cure, a pressure carburettor, took until 1943.

GO DEEPERInjection against the carburettor →

· WHY IT MATTERED

A gun through the propeller hub

From the F model a cannon fired through the hollow propeller shaft — the Motorkanone — so its shells came out exactly along the line the pilot was looking, with no need to set the wing guns to converge at some chosen range. Later versions added a 30 mm cannon there that could bring down a bomber with a few hits.

· WHY IT MATTERED

Range lost the battle

Four hundred litres of fuel gave the 109 E about 660 km of range and a combat radius of roughly 300 km. From the Pas-de-Calais that meant minutes over the target and a Channel to recross with the fuel light on; escorting bombers at their speed made it worse. The 300-litre drop tank came in August 1940 — too late for the summer. Performance was never the 109’s problem. Fuel was.

· THE ENGINE

Daimler-Benz: the injected inverted V-12

The DB 601 hung its cylinders upside down like the Jumo, and injected fuel directly at 1940 pressures that were state of the art. Its supercharger was driven through a hydraulic clutch that a barometer adjusted continuously with altitude, so instead of the step of a two-speed gearbox the blower sped up smoothly as the air thinned. The DB 605 that followed grew to 35.7 litres, and the late-war G models could spray water and methanol into the intake to run 1,800 PS for a few minutes — the same trick a modern turbo car uses to hold boost without knocking.

DB 601A · inverted V-12 · 33.9 L · Bosch direct injection · clutch-driven supercharger · 1,175 PS; later DB 605 with MW 50 to 1,800 PS

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· WEAPONS AND SPECIALITY

Two machine guns, two cannon, and a cannon in the nose

The 1940 Emil fired two rifle-calibre machine guns over the engine and two 20 mm cannon in the wings: about 2.1 kg of metal a second, but the cannon drums held only sixty rounds — seven seconds of firing — after which it was back to the machine guns. The 1943 Gustav moved the heavy guns to the nose: two 13 mm machine guns and one 20 mm cannon through the spinner, the same weight of fire with far more rounds behind it. Gondola cannon under the wings doubled it again for bomber hunting, at a cost in handling that fighter pilots hated.

· TRY IT

Minutes over London: what 400 litres buys

The lab’s range tab is set to the Emil: internal fuel, the drop tank it did not have that summer, a Channel crossing each way and a reserve. What is left is combat time over the target — the number that decided the Battle of Britain more than any performance figure.

Readout

Power1,108 hp

Per engine1,108 hp

True airspeed560 km/h

Service ceiling10,500 m

A simplified model calibrated to the published rating and top speed — the shape of the curve is the point, not the third decimal.