Picture a beer keg with wings. Now bolt a nine-cylinder radial to the front, wedge a nervous pilot in behind it, and paint a red star on the side. Congratulations: you have just imagined the Polikarpov I-16, the stubbiest, twitchiest, most quietly revolutionary fighter of the 1930s — and very possibly the most important aeroplane most people have never heard of.

Because for all its barrel-shaped absurdity, the I-16 was a genuine first. When it clawed into the sky over Moscow in December 1933, it became the world’s first low-wing cantilever monoplane fighter with retractable landing gear to actually reach squadron service. Not a prototype. Not a one-off. A frontline fighter that made every biplane on Earth look like a museum piece overnight.

It fought in Spain, in Mongolia and across the burning fields of 1941. It was loved, feared and cursed in four languages. And it flew, by all accounts, like a caffeinated shopping trolley. This is its story.

A donkey, a rat and a fly walk into a design bureau

While tinkering with his I-15 biplane, Nikolai Polikarpov did something faintly heretical for 1933: he decided the future was a monoplane. Not a strut-braced, wire-tangled compromise, but a proper low-wing cantilever design with the landing gear tucked away in flight. On 30 December 1933 the legendary test pilot Valery Chkalov hauled the squat little prototype off the ground, and Soviet aviation quietly stepped into the modern age.

Here is the “first” that matters, and it is worth getting right. America’s Boeing P-26 Peashooter beat the I-16 into the air as a monoplane fighter — but the P-26 kept its wheels hanging out in the breeze and braced its wings with external wires. The I-16 was the first to combine the full modern package — cantilever wing, retractable gear, radial in a cowling — and then reach operational squadron service with it.

The retractable gear, mind you, was less “push a button” and more “arm day.” The pilot cranked the wheels up and down by hand — roughly forty-odd turns of a stiff, jam-prone jackscrew that demanded genuine muscle. Progress, in 1934, came with a workout.

Twitchy, terrifying, and rather good at its job

Let us not sugar-coat it: the I-16 was a handful. The engine sat too close to the centre of gravity and the pilot too far behind it, leaving the aircraft unstable and, in one blunt phrasing, impossible to fly hands-off. Forward visibility over that fat radial was essentially theoretical. And yet it was fast and astonishingly agile — briefly among the fastest, lightest production fighters in the world, with a roll rate so vicious it could snap through a roll in well under two seconds.

Those hair-trigger controls that terrified novices became a gift in expert hands. A modern warbird pilot who flew a restored example decades later put it plainly.

And here is a myth worth puncturing. The I-16’s reputation as a spinning death-trap is largely folklore. Back in 1934, Chkalov deliberately threw the prototype into scores of spins and found the recovery genuinely benign. The plane’s real sins were its instability and brutal ergonomics, not some cartoonish urge to kill you. It demanded respect, and rewarded skill.

Rata, Mosca, and the long fighting retirement

The I-16 got its baptism of fire in Spain. From November 1936, Soviet-supplied fighters tore into the Nationalists’ biplanes and dominated the sky — right up until the Messerschmitt Bf 109 arrived and rewrote the rules. Nationalist pilots called it the Rata, the rat; Republicans affectionately called it the Mosca, the fly. Same aeroplane; only your uniform decided the insult.

Then came Mongolia. At Khalkhin Gol in 1939, hundreds of I-16s dogfought the nimble Nakajima Ki-27 — and it was here, on 20 August 1939, that Captain Zvonarev fired an RS-82 rocket into a Ki-27 from around a kilometre out, one of the first successful air-to-air rocket kills in history. A barrel-shaped biplane-killer had quietly opened the age of the air-to-air missile.

By 22 June 1941, though, time had run out. When Germany invaded, well over 1,500 of the Soviet Air Force’s frontline aircraft were I-16s — obsolete, out-climbed and out-run by the Bf 109, yet thrown into the meat-grinder because they were what the VVS had. It could still out-turn an Emil, and some desperate pilots resorted to ramming. The little donkey carried the load until newer fighters arrived. Not bad for a keg with wings.

Sources: Wikipedia (Polikarpov I-16); William Green, Warplanes of the Second World War Vol. 3 (1961); Dave Morss, Flying the Polikarpov (aafo.com); Warbirds Over Wanaka.