In 1982, forty years after the last one made sense, a Soviet design bureau flew a jet attack aircraft with a rear gunner.

Not a token installation. A proper remotely-controlled tail turret with a twin-barrelled 23 mm cannon, aimed by a second crewman sitting in his own pressurised cockpit above the trailing edge of the wing, facing backwards, watching for fighters.

The Ilyushin Il-102 lost to the Sukhoi Su-25 and only two were built. It has been ridiculed as a Second World War aircraft that wandered into the missile age. That is not quite fair, and the argument it lost is one that has never really been settled.

The competition Ilyushin lost twice

In 1967 the Soviet Air Force decided it wanted an armoured jet attack aircraft again. Vietnam and the Middle East had demonstrated what fighter-bomber pilots had been saying for years: a fast jet optimised for air combat is a poor instrument for loitering over a battlefield being shot at.

Several bureaux competed. Sukhoi offered the T8, a clean-sheet single-seater that became the Su-25. Yakovlev offered the Yak-25LSh and Mikoyan the MiG-21LSh. Ilyushin proposed the Il-42, a deep modernisation of its own Il-40 of 1953, which had been cancelled in 1956 when the Soviet Union abolished its attack aviation arm outright and scrapped five nearly complete aircraft.

The 1969 decision went to the Sukhoi T8 and the MiG-21LSh. The Il-42 was stopped.

Ilyushin, under Genrikh Novozhilov, carried on anyway. The programme was renamed Il-102 and continued as what one account calls a semi-legal in-house effort, short of money and actively opposed by the Ministry of Defence, which regarded it as a waste of resources next to the Su-25.

Why a tail gunner in 1982

The rear turret looks like nostalgia. Ilyushin's reasoning was more specific than that.

An attack aircraft over a battlefield spends its time low, slow and busy, looking down. Its greatest vulnerability is a fighter coming from behind, and the pilot of a single-seater is the last person likely to notice. Ilyushin's answer was a second pair of eyes permanently pointed the other way, backed by infrared decoys, active jamming, and a gun.

The intended chain of events was this: the gunner sees the fighter, the decoys and jamming spoil its missile shot, the aircraft's manoeuvrability does the rest, and an attacker forced to close to gun range finds itself flying into the GSh-23L. The turret was not there to shoot fighters down. It was there to make the approach expensive enough that they would not try.

The forward gun was equally unconventional. Rather than fixing the 30 mm cannon to fire straight ahead, Ilyushin mounted it on a ventral installation that could be locked in two positions: horizontal for forward fire, or angled downwards, so the aircraft could rake a target while flying level over it instead of diving at it.

Where the armour went

The Il-2 and Il-40 had been built around a single armoured bathtub containing everything vital. The Il-102 was too big and heavy for that, so Ilyushin did something cleverer and stranger.

The crew cabins got armour. The engines and fuel system got some. The fuel tanks got none at all. Instead they were concentrated in the centre fuselage and shielded by everything around them: the crew cabins in front and the gunner's installation behind, the engines on each side, and the ventral cannon underneath. The tanks were also filled with reticulated foam to suppress explosions.

In other words, the aircraft's own equipment was the armour. Both crew members sat on K-36 series ejection seats rated to work at zero speed on the ground, and the wing was thick enough to carry internal bomb bays as well as external pylons, which is how a 22-tonne aircraft ends up carrying 7.2 tonnes of weapons.

It flew, and it flew well

By early 1982 the prototype was finished. On 20 January the Air Force commander-in-chief, P. S. Kutakhov, inspected it and came away supportive, as did the aviation industry minister I. S. Silayev. The Ministry of Defence did not change its mind.

The first flight took place on 25 September 1982. Between then and 1984 the aircraft flew 250 times, and the record is consistent on one point: nothing broke. No airframe damage, no serious onboard system failures. It was reported as highly manoeuvrable, with a minimum turn radius of about 400 metres, which for a 22-tonne aircraft is remarkable.

It was grounded in 1984 when the engines reached the end of their approved life, and by then the argument was over. The Su-25 was in full production and had been in combat in Afghanistan. The Il-102 was heavier, carried more, defended itself better, and offered nothing the Air Force considered worth a second production line.

That second cabin is the whole story. It meant a second crewman to train, feed, seat, protect and risk, on every sortie, for a defensive capability the Air Force did not believe it needed. A brief attempt to revive the programme in 1986 ran into defence cuts and the decision to leave Afghanistan, and died.

The argument nobody has settled

The Il-102 appeared in public at the start of the 1990s, at Zhukovsky, and was offered for export. There were no takers. It sits today at the Gromov Flight Research Institute, a large grey aeroplane with an unmistakable tail.

The uncomfortable part is what happened afterwards. Single-seat attack aircraft have spent the last four decades being shot at from behind by things their pilots never saw, and the modern answer to that problem is not a gunner but a missile approach warner, a towed decoy and a datalink. Ilyushin was asking the right question and reached for the only tool its era had already built.

Compare it with the A-10 Thunderbolt II, which went the other way entirely: one seat, one enormous gun, titanium bathtub, and no rearward defence at all beyond flares and speed. Both aircraft were designed for the same war. Only one of them worried about what was behind it.

Sources: World Air Power Journal, Volume 17; Bill Gunston, The Osprey Encyclopedia of Russian Aircraft 1875–1995; Vintage Aviation News; GlobalSecurity.org.