Picture a Soviet bomber crossing the Arctic at night in 1955. Somewhere ahead of it, a single American pilot sits in a fighter with no guns at all. He is not looking out of the canopy. He is staring into a radar scope, steering a small dot into the centre of a circle, while a computer decides the exact moment to fire 24 rockets into the dark.

That was the job of the North American F-86D, the Sabre that most people never think of. It wore the famous name of the Korean War dogfighter, but under the skin it was a different aeroplane: a radar-nosed, afterburning, rocket-armed all-weather interceptor that became known as the “Sabre Dog”.

It also did something no previous US Air Force radar fighter had managed. It put the radar, the fire control and the flying into the hands of one person. And along the way, two standard production F-86D Sabre Dog interceptors took the world absolute speed record.

A Sabre in name only

The day-fighter F-86 Sabre was built to see its enemy in clear daylight and kill it with six .50-calibre machine guns. That was no use against bombers arriving in cloud or darkness. New Soviet jet and turboprop bombers such as the Tu-16 Und Tu-95 would also be much faster than the piston bombers of the Second World War, shrinking the time an interceptor had to aim and fire.

North American began work in March 1949 on an all-weather derivative. So much had to change that the Air Force first gave it a new designation, YF-95. The prototype flew on 22 December 1949, and the designation reverted to YF-86D before production began. The family resemblance was largely skin-deep: the F-86D shared only about 25 percent of its parts with the original Sabre.

It had a wider, longer fuselage, a hinged clamshell canopy, enlarged tail surfaces and a black radome for the AN/APG-36 radar perched above a reshaped intake. Behind the pilot sat a General Electric J47-GE-17 with an afterburner, rated at 5,425 lbf (24.1 kN) dry and 7,500 lbf (33.4 kN) with reheat. The guns were gone entirely.

One pilot, one computer

Before the Sabre Dog, every US Air Force fighter with search radar carried a second crewman to run it. The F-94 Starfire Und F-89 Scorpion both had a radar operator in the back seat. The F-86D replaced that person with automation, in the form of the Hughes E-4 fire control system.

Older systems had the pilot fly a pursuit course that ended up behind the bomber, squarely in the arc of its tail guns. The E-4 computed a lead-collision course instead, bringing the fighter in from ahead and to the side. Once the radar locked on, a steering dot appeared on the scope. Keep the dot in the centre of a small circle, and the aircraft was on the right course. An outer “time-to-go” circle shrank as the firing point approached.

Four seconds before firing, the pilot was prompted to arm the rockets. Then the system fired them automatically at the computed instant. It was a remarkable workload for one person, flying on instruments at night while watching symbols on a scope, and it explains why the early E-3 and E-4 electronics gave so much trouble.

Not A Pound For Air To Ground on why the F-86D, the most common American interceptor of the 1950s, is so often forgotten.

Mighty Mouse

The weapon at the end of all that computation was the Mk 4 Folding-Fin Aerial Rocket, better known by its service nickname, “Mighty Mouse”, after the cartoon character. Each rocket was 2.75 inches (70 mm) across, about 1.2 metres long and weighed 8.4 kg, with a warhead of roughly 2.7 kg. Four fins flipped open at launch to stabilise it.

The F-86D carried 24 of them in a retractable tray in its belly that dropped down only for the attack, and the pilot could fire them in salvoes of 6, 12 or 24. The theory was simple: one hit could destroy a bomber, so a spread of rockets fired at the right moment should guarantee one.

The practice was less kind. The rockets dispersed widely after launch, and a 24-round salvo could scatter across an area the size of a football field. In August 1956, two F-89 Scorpions sent after a runaway US Navy drone over California fired 208 of them without bringing it down, an episode now remembered as the Battle of Palmdale. Guided missiles were the obvious answer, and the Mighty Mouse found its real career later as an air-to-ground weapon.

The fastest Sabres of all

For all its electronic complexity, the Sabre Dog was quick. In November 1952, Captain J. Slade Nash of the Air Force Flight Test Center flew F-86D 51-2945 over a 3-kilometre course beside the Salton Sea in southern California, at around 125 feet (38 m). His average of about 698.5 mph (1,124 km/h) broke the world absolute speed record that an F-86A had set in 1948 at 670.981 mph.

The Salton Sea was chosen with care. Its surface lies more than 70 metres below sea level, and the dense, hot air there raises the speed of sound, giving a transonic jet more room before compressibility trouble sets in. On 16 July 1953, Lieutenant Colonel William F. Barns used the same course to push the record to about 715.7 mph (1,151.8 km/h) in F-86D 51-6145.

Barns’ aircraft was a standard production airframe, the first of the Block 35 models, and it flew with a full load of 24 rockets. A combat-ready interceptor, straight off the line, briefly held the title of fastest aeroplane in the world.

Teething troubles and a long service life

The record runs hid a difficult start. Problems with the E-3 and E-4 electronics held up deliveries, and it took until 1953 for fully functioning F-86Ds to reach the squadrons of Air Defense Command in numbers. Engine and fuel-system problems led to a fleet-wide grounding late that year and a large modification programme in 1954.

Once the bugs were out, the Sabre Dog became the backbone of American continental air defence in the mid-1950s. More than 2,500 were built. From 1956, 981 were rebuilt as the F-86L, with a redesigned wing and new electronics, and Air National Guard units flew those into the mid-1960s.

The National Museum of the US Air Force looks at its F-94C Starfire and F-86D Sabre, two answers to the same all-weather interceptor problem.

NATO air forces got the F-86K, a simplified export version that swapped the rocket tray for four 20 mm cannon. North American built 120 of them and Fiat assembled 221 more in Italy for the Italian Air Force, France, the Netherlands, Norway and West Germany. Surplus F-86Ds went to Denmark, Greece, Japan, the Philippines, South Korea, Yugoslavia and others. The Japan Air Self-Defense Force took 122 and called the type “Gekkō”, or Moonlight.

Period footage of US Air Force F-86D Sabre interceptors, from the Aviation videos archives channel.

The ancestor of the automated interceptor

The F-86D never fought the war it was built for, and its rockets were a dead end. But the idea at its heart outlived it. A single pilot, guided by radar and a fire-control computer that chose the moment to shoot, became the template for the F-102 Delta Dagger Und F-106 Delta Dart that replaced it.

The original Sabre is remembered for what it did in MiG Alley. Its radar-nosed cousin deserves to be remembered for something quieter: it was the moment the fighter pilot first handed the trigger to a computer, and kept the title of fastest man alive while doing it.

Sources: Wikipedia (North American F-86D Sabre; North American F-86 Sabre; Folding-Fin Aerial Rocket; Battle of Palmdale), Texas Military Forces Museum, This Day in Aviation, Air & Space Forces Magazine, McChord Air Museum, Pima Air & Space Museum