The Skyknight was designed by Douglas — under the direction of the famed engineer Ed Heinemann — to a late-1940s US Navy requirement for a carrier-capable, radar-equipped night fighter. The defining problem was the radar itself: the sets of the day were large and heavy and needed a dedicated operator to run them. Rather than squeeze the equipment into a conventional fighter, Heinemann’s team designed the whole aircraft around it.

The result was a wide, deep fuselage with the pilot and radar operator seated side by side, a big nose radome, and two turbojets buried in the belly. It was a straightforward, robust design rather than a high-performance one. The prototype XF3D-1 first flew on 23 March 1948, and the Skyknight entered US Navy and Marine Corps service at the start of the 1950s as a dedicated all-weather and night fighter.

The Skyknight’s broad, slab-sided, deep-bellied fuselage — needed to house the radar, two side-by-side crew and two engines — gave it an unmistakable, faintly comical bulk. Crews nicknamed it “Willie the Whale,” and the name stuck. It was never going to win a beauty contest against the sleek, swept-wing fighters that were arriving at the same time.

But the shape was a consequence of the mission, not a mistake. The wide cockpit let the pilot and radar operator work together directly, passing information by voice and gesture in the dark. The deep fuselage held the electronics and, later, made the Skyknight easy to pack with jamming gear. The Whale looked ungainly, but every line of it served the job it was built to do.

The heart of the Skyknight was its Westinghouse AN/APQ-35 radar system — in fact a suite of three separate radars working together. A search radar (AN/APS-21) found targets at a distance; a gun-laying radar (AN/APS-26) locked on and aimed the aircraft’s four 20 mm cannon; and a tail-warning radar watched the rear hemisphere for threats approaching from behind.

It was advanced for its time and gave the Skyknight a genuine ability to intercept and destroy other aircraft in complete darkness — but it was also a maintenance nightmare, built from thousands of fragile vacuum tubes that ran hot and failed often. Keeping the radar working took constant effort from the ground crews. When it did work, though, it turned the slow, plain Skyknight into the most effective night fighter of its day.

Almost uniquely among jet fighters of its generation, the Skyknight had no ejection seats. When it was designed, reliable ejection seats were not yet standard equipment, and the side-by-side cockpit would have made a conventional twin-ejection installation difficult. Douglas chose a different solution: an escape chute.

In an emergency the crew jettisoned a hatch and slid down a chute built into the fuselage, dropping clear out of the underside of the aircraft, well away from the tail. It was an unusual system — more like bailing out of a bomber than punching out of a fighter — and it is one of the quirky details that make the Skyknight stand apart from its contemporaries.

The Skyknight’s place in history was secured over Korea. By late 1952 American B-29 bombers had switched to night raids to escape the MiG-15s that dominated the daylight sky, only to find that radar-directed MiGs were intercepting them in the dark. The Marine night-fighter squadron VMF(N)-513, the “Flying Nightmares,” brought its Skyknights in to escort them.

On the night of 2 November 1952 a VMF(N)-513 Skyknight crew — pilot Major William Stratton and radar operator Master Sergeant Hans Hoglind — detected, tracked and shot down an enemy jet entirely by radar. It is regarded as the first radar-guided jet-versus-jet kill at night in aviation history. Days later another Skyknight crew downed a MiG-15 by night, and the type went on to claim more night victories than any other Navy or Marine aircraft of the war.

The Skyknight’s core job in Korea was protecting the B-29 Superfortress bombers on their night missions over the north. Flying ahead of and around the bomber stream, the Skyknights used their radar to detect intercepting MiGs before the MiGs could reach the bombers, and to engage them in the dark. It was demanding, methodical work — the very opposite of a swirling dogfight.

Over the course of the campaign the Skyknights shot down several enemy aircraft at night, more than any other US Navy or Marine Corps type in the war, and — remarkably — not one Skyknight was lost to an enemy fighter. For the bomber crews, whose losses to night interception dropped sharply once the Skyknights arrived, the ungainly Whale was one of the most welcome aircraft in the theatre.

Well before missiles came to dominate air combat, the Skyknight served as an important flying testbed for the US Navy’s early air-to-air missile programmes. Specially equipped F3Ds — the F3D-1M and F3D-2M — carried the first-generation Sparrow (AAM-N-2) beam-riding missile, and Skyknights were among the very first jets to launch radar-guided missiles at aerial targets.

This was pioneering work in the early 1950s, at the dawn of the guided-weapon age, and it fed directly into the missiles that would arm the fighters of the following decades. The Skyknight never fired a missile in combat, but its role in developing and proving the technology was a genuine and often-overlooked contribution to the future of air warfare.

For its first fourteen years the aircraft was known by the US Navy’s old designation system as the F3D — the third distinct fighter (F3) type from Douglas (D). In 1962 the United States adopted a single, unified aircraft designation system across all its armed forces, and the Skyknight’s labels changed accordingly.

The F3D-1 became the F-10A, the F3D-2 became the F-10B, and the electronic-warfare F3D-2Q became the EF-10B. The aircraft itself did not change — only the designation — but this is why the same machine appears in sources as both the F3D and the F-10 depending on the date. The Skyknight is one of the aircraft most affected by the change, since so much of its later career, in Vietnam, was flown under its new F-10 identity.

The Skyknight’s most unexpected second life was as an electronic-warfare aircraft. Its roomy fuselage, designed to hold a radar and its operator, proved ideal for the bulky jamming and electronic-intelligence equipment of the day. Converted aircraft — originally the F3D-2Q, redesignated EF-10B — became the US Marine Corps’ dedicated electronic-warfare jets.

From 1965 the Marine squadron VMCJ-1 flew EF-10Bs over North Vietnam, detecting and jamming the radars of anti-aircraft guns and surface-to-air missiles and helping to protect American strike aircraft. They were among the first US tactical electronic-warfare jets in that war, flying dangerous missions deep into defended airspace. The elderly Whales soldiered on in the role until the late 1960s, when newer aircraft finally replaced them — more than twenty years after the type first flew.

The Skyknight was produced in a modest run of around 265 aircraft, but in a surprising variety of forms. The two main fighter versions were the F3D-1 (later F-10A) and the more powerful, more numerous F3D-2 (F-10B). From these came the missile-testbed F3D-1M and F3D-2M, which carried the early Sparrow air-to-air missile, and trainer versions such as the F3D-2T used to teach radar interception.

The most important derivative was the electronic-warfare F3D-2Q, redesignated EF-10B, which carried jamming and electronic-intelligence equipment in place of the fighter’s weapons. There were also drone-director and utility conversions late in the aircraft’s life. For an aircraft built in small numbers, the Skyknight was adapted to a remarkable range of roles.

As with most early Cold War military aircraft, there is no single reliable, transparent public figure for the Skyknight’s unit cost, cost per flight hour or total programme cost. It was procured in modest numbers in the early 1950s through military contracts rather than at a published list price, and consistent lifetime cost data for the type is not available. Any single figure quoted for it should be treated with caution.

In broad terms, a twin-engine, two-seat, radar-equipped night fighter with an elaborate electronics fit was an expensive and maintenance-intensive aircraft for its day — the temperamental valve-based radar alone demanded a great deal of skilled ground-crew time. Rather than invent numbers, we list the cost fields here as “not reliably recorded.”

By the standards of the swept-wing fighters arriving alongside it — the MiG-15, the F-86 Sabre — the Skyknight was slow, heavy and unmanoeuvrable. In a daylight turning fight it would have been hopelessly outclassed. But it was never meant for that. It was built to be a stable, patient radar platform that could find and destroy other aircraft in darkness or bad weather, when the nimble day fighters were blind.

In that specialised niche the Skyknight excelled precisely because of the qualities that made it a poor dogfighter: its steadiness, its roomy cockpit for two crew to work the radar, and its ability to carry a heavy electronics fit. It is a classic case of an aircraft designed for a job doing that job superbly, even while looking utterly outmoded next to its glamorous contemporaries.

Because the Skyknight was built in small numbers and retired decades ago, survivors are relatively few, and all of them are in the United States — fitting for an aircraft that was flown only by American forces. A handful are preserved in US museums, including examples at the National Naval Aviation Museum and other aviation and Marine Corps collections around the country.

These preserved Whales are the last tangible reminders of a genuinely pioneering aircraft — the machine that made the first radar night jet kill, helped bring the guided missile into being, and flew as an electronic-warfare jet over two wars. For an aircraft that never sought the limelight, the surviving Skyknights are a quiet but remarkable legacy.