• History of Flight

Beautiful Climber

In the summer of '58, nothing was faster to 50,000 feet.

• By Carl Posey
• Air & Space Magazine, July 01, 2006

Near dawn on a sparkling spring day, a tailless jet fighter shaped like a manta ray taxied into position on Runway 21 at the Naval Air Missile Test Center at Point Mugu, California. Pointing the airplane into the dense, cold air flowing off the Pacific, Marine Corps Major Edward N. LeFaivre applied full power with the brakes on, then, brakes off, lit the afterburner. The aircraft screamed down the runway for the ten seconds it needed to reach 150 mph and lifted off in a 70-degree climb, tracked by missile-range cameras and radar. Two minutes and 36.05 seconds after releasing the brakes, LeFaivre was at 50,000 feet. It was the fastest time to that altitude in history.

The airplane that set that mark was not a daring experiment in delta-wing technology, but a Navy fighter that had been in development for more than a decade, had served with the fleet for two years, and was already entering the twilight of its service life. Yet as of May 23, 1958, Ed LeFaivre’s airplane could still outclimb any other military jet, foreign or domestic.

Douglas designed the aircraft to meet the Navy’s 1947 requirement for a land- or carrier-based jet interceptor quick enough to catch and kill an approaching enemy bomber flying at 500 knots (575 mph) and 40,000 feet within a 100-mile radar range. To do this, the jet would have to reach 40,000 feet in five minutes and be able to fight when it got there.

Named the Skyray for the unique shape of its wing, LeFaivre’s aircraft was known by those who flew and cared for it as the Ford, from its designation, F4D, and fighter pilots’ penchant for understatement. In fact, there was nothing Ford-like about the Skyray. It was exotic and fast, the first of the high-performance designs born during the post-World War II fascination with delta wings, which sprouted on military aircraft around the world like fins on late-1950s automobiles. Many had been inspired by the 1930s experimentation of German aircraft designer Alexander Lippisch. He, in turn, attributed the delta wing to a gift of a zanonia seed, sent him by a colleague during the 1920s. Triangular and airworthy, zanonia seeds can glide a good distance from their parent vine on the weak thermals of the Indonesian rainforest.

The more immediate provenance of the Skyray was a visit to Paris in the week following VE Day, during which Douglas engineers Gene Root and A.M.O. Smith acquired a trove of German wind tunnel data and were able to listen to Lippisch, then in Allied custody, brief his captors on the flying-wing interceptors he believed were aviation’s future. Smith and Root returned to El Segundo and the legendary California design-works run by Edward H. Heinemann, where engineers started playing their own supersonic variation on the Lippisch theme.

“The original layout we had at Douglas was very much like Lippisch’s plan, which had a sweepback of 45 degrees,” recalls Malcolm J. Abzug, a control and stability engineer present at the Skyray’s creation. “As I remember, it was okay, but the airplane couldn’t be balanced. So the sweepback was increased to 52.5 degrees.” Increasing the degree of sweep balanced the aircraft by shifting the wing’s area in relation to its center of gravity, the point around which the aircraft pivots in pitch. “All this was under A.M.O. Smith,” Abzug says. “His first name was Apollo, so he went by initials; we called him Amo Smith.”
The first design was a wing that could easily have flown off the drawing board of Lippisch himself. Then, like a reptile morphing into a bird, the new fighter began to take shape: A rudimentary fuselage appeared, and the wings shrank to a smaller triangle.
One of the youngest members of the design team was Erven Heald, who had come to Douglas in 1940, fresh from the University of Michigan. “Heinemann would just come up with a design and take it to one of the engineers to be turned into an airplane,” he says. “When he showed me the Skyray he asked if we could make one, and I said yes, but the center-of-gravity travel can’t be more than about five percent.” That limited what could be hung on the airplane, and where. “My role was just the flying qualities, how to make it stable and controllable.” With a grin, he adds, “Stable and controllable was a challenge.”
In October 1950, not quite a year after the Navy awarded a contract to build two prototype Skyrays, Douglas rolled out the XF4D. It was neither a flying wing nor a delta-wing airplane, but something in between. To those who would come to love the craft, its planform looked like a valentine. To others it looked like the ace of spades.

Because the Skyray had no horizontal tail, pilots controlled pitch and roll with elevons on the trailing edge of the wing—control surfaces that have combined the functions of ailerons and elevators on all delta-wing airplanes right up through the Concorde. The Skyray’s elevons were boosted hydraulically. Were the hydraulic system to fail, the stick could be extended about a foot to give the pilot enough leverage to move the control surfaces. Pitch trimmers augmented the elevons. Control in yaw was provided by a swept dorsal fin with an unboosted rudder.

Westinghouse had not yet delivered the J40 engine specified by the Navy, but with deadlines looming, Douglas jury-rigged the prototypes with Allison J35-A-17s, which left the airplanes sorely underpowered. In the fall of 1950, the prototypes were trucked to Edwards Air Force Base in California to see if they were more than just a pair of pretty faces.

First flight, and the harbinger of what the Chinese would call interesting times, came on the morning of January 21, 1951. Douglas test pilot Larry Peyton, whose experience was mainly in transports, was chosen for this run. The airplane was to be flown on manual controls to determine some of the nuances of takeoff trim. Then, after some light maneuvering, back it would come to the lake bed. Piece of cake.

Peyton lifted off at 140 mph for what he intended to be a gradual climb to 10,000 feet. The Skyray had other ideas. As speed increased, so did nose-up pitch, even with the stick pressed against the instrument panel. When Peyton hit the trimmers, the nose pitched sharply down, and pulling the stick all the way back had no effect. Another try with the trimmers and the Skyray flared and mushed back to earth.

With the vast Edwards lake bed largely ahead of him, Peyton stayed with it, lifting off again. He brought the Ford into a steady climb at 160 mph—with the stick full forward. After a few test maneuvers, he turned for home and fluttered to the ground, fighting the weird pitch behavior. He never flew the Skyray again.
Another Douglas test pilot, Russell Thaw, took up the preliminary work of fixing the trim problems on takeoff. Then the Skyray passed to Robert Rahn, a top hand among the experimental test pilots. He had flown Spitfires with the Army Air Forces during World War II, and had since tested a host of aircraft types for Douglas.

Having seen Thaw’s flights, Rahn was not sure he wanted to fly the XF4D, but in October 1951, he tried it on. “I flew on manual flight control and quickly learned why Larry wanted no part of the Skyray,” he wrote in his memoir, Tempting Fate. “The stick forces were exorbitant for the small control-surface deflection achieved. The plane was tough to handle unless below 200 knots and in smooth air—not a good sign for a fighter which may have to make an approach onto the pitching deck of an aircraft carrier at night.”
Still, the Skyray’s potentially breathtaking performance, maneuverability at altitude, and the forgiving qualities of that huge wing found a spot in Rahn’s affections. “This aircraft,” he wrote, “was just what I had been looking for in a fighter since my flying days in the Spitfire. The F4D was a fighter pilot’s dream.” As Rahn would soon learn, it could also be a fighter pilot’s nightmare.

“The Skyray,” says Mal Abzug, “was the first Douglas airplane to have the phenomenon known as inertial coupling, in which the airplane goes out of control at high roll rates. It’s caused by the way the weight is distributed. Ever since airplanes were made with the swept wings, they’ve all had that property. First airplane was the F-100. We had a problem about the same time, around 1950. The Skyray was one of the pioneering airplanes in this area.”
And how.

Fighter aircraft are required to be able to enter and recover from spins, defined as uncontrolled rotations around any axis of a fully stalled airplane. Conventional recovery is a simple matter of applying opposite rudder to stop the rotation and moving the stick forward to get the nose down and restore airflow over the wing. The Skyray evidently thought this was too easy.

After preliminary spin tests with conventional recoveries, Bob Rahn took his prototype, now equipped with a non-afterburning but more powerful J40 engine, into the California skies to see how it performed with the center of gravity slightly aft, a change resulting from the installation of the new engine.

“I was down on the desert floor in the communications shack,” Abzug recalls. “At 35,000 feet he kicked it over in a spin. There was a long silence. Then he finally said, ‘Jesus Christ!’ ”
When he entered the spin at 35,000 feet, Rahn had intended a couple of turns to the left, then recovery. Instead, he later wrote: “Spun one and a half turns then reversed direction, even as I held full pro-spin controls (full left rudder and full aft stick).” With the aircraft now in a slow, flat spin to the right, Rahn tried something else: He added left rudder against the spin and neutralized the stick. “The XF4D rolled abruptly upside down and started spinning inverted,” Rahn reported. “I experienced severe oscillations in pitch as much as 120 degrees in a half turn and fell through the sky upside down. At this extreme attitude in pitch, I had the impression I was in a 60-degree, nose-down, upright spin.”
Rahn deployed the spin recovery chute at 10,000 feet above sea level, just half a mile above the high desert floor, and the Skyray, having done its thing, resumed normal behavior. But he had been seriously spooked about spin testing the Ford.

Wind tunnel work indicated that Skyray pilots would have to unlearn what they thought they knew about spin recovery. In an upright spin, the pilot had to apply full opposite rudder, but also full aileron with the direction of spin. “I was the guy who briefed Rahn,” says Abzug. “Ailerons with the spin: They were the predominant spin control. I had a hard time convincing him to do it.” In the end, Rahn followed the new guidance and solved the problem, more or less. But the Ford never lost its reputation for unrecoverable spins.

When things worked well, however, they worked very well indeed. A year and a half into the Ford’s testing—in mid-1952—a team of Navy and Marine pilots came to Edwards to evaluate the product. They noted its quirks but liked what they found at altitude, where the Skyray’s big wing and inherent instability let it out-turn anything then flying. Rahn wrote approvingly, “All of the Air Force chase airplanes fell out of the sky during these maneuvers.”
Perhaps the highest praise came from Marine Major Marion Carl, one of the evaluating pilots, who said: “If we had this airplane now in Korea, I could just pop off the MiGs—one, two, three.”
A month later Rahn put the cherry on top. The nominally supersonic Skyray had gone through 18 months of testing without reaching Mach 1, a milestone delayed by severe buffeting and the nose-down “tuck under” peculiar to swept-wing aircraft in the transonic region. (As aircraft approach Mach 1, shock waves begin to form in the airflow over the wings and the center of lift, the point at which the force acts on the wing, shifts aft. This shift causes the aircraft to pitch down. The Skyray was equipped with trimmers, in part to counter this effect.) After considerable tweaking, Rahn put his Ford into a shallow dive and at 30,000 feet pushed past the speed of sound—the first supersonic moment for a delta-wing airplane.

With this achievement, the Skyray was a natural to try for the world closed-course speed records, which had recently passed from the Air Force’s F-86D to the Royal Air Force’s Hawker Hunter. After fitting an afterburner to the J40, the team ran enough trials to see how the Ford would handle with the added power. Lieutenant Commander James Verdin, a veteran Navy combat pilot, was set to try for the three-kilometer speed record, undaunted by the fact that it had just been broken again by a British Vickers Supermarine Swift in Libya going 737.3 mph.
On Saturday, October 3, after several failed attempts, Verdin’s Skyray was streamlined, polished, stuffed with fuel pre-cooled for increased capacity, and ready for its final try. Verdin flew four passes 100 feet above the ground at an average speed of 752.9 mph—more than enough to strip the title from the British. Only eight minutes elapsed between the beginning of the first pass and the end of the fourth one, with the afterburner guzzling 3,450 pounds of fuel.

Two weeks later, Bob Rahn took on the 100-kilometer record at the Edwards course, a circle defined by 16 smoke pots and painted pylons. Flying 100 feet off the ground, Rahn flew straight lines to each pylon, rounding them with a brutally sharp, 70-degree bank. His average speed on the final, official run: 728.11 mph, a new world mark.
The Skyray—and Heinemann’s design shop—entered a brief golden age. While Rahn and his colleagues had been wringing out one prototype at Edwards, Navy and Marine pilots had been growing the second prototype’s sea legs at Naval Air Station Patuxent River in Maryland. The Skyray was headed for the fleet.

In mid-December 1953, the airplane’s reputation was burnished further when Heinemann received the Collier Trophy for the Skyray; he shared the honor for the first supersonic fighter with North American’s Dutch Kindelberger, father of the F-100 (and Heinemann’s former boss). And there was more good news: Another Heinemann creation, the D-558-2 Skyrocket, made Scott Crossfield the first human to reach Mach 2 in an airplane and enabled Marion Carl to set an unofficial world altitude mark: 83,235 feet.

By this time no one believed Westinghouse could deliver a reliable afterburning J40. (Indeed, the J40 fiasco would drive the company out of the jet engine business.) But Heinemann had seen the problem coming, and had built the Ford’s fuselage with enough space to accommodate a larger engine: Pratt & Whitney’s afterburning J57-P-2, with 14,500 pounds of thrust. The Skyray would finally have enough power to serve as the interceptor that Douglas and the Navy had envisioned.
Production began in 1954. Once the F4D-1s were ready for flight testing, they were towed across Imperial Boulevard to Mines Field, now better known as Los Angeles International. The airplanes were supposed to include an Aero-13 fire control system, built around the Westinghouse An/APQ-50 radar, a system that could see targets 18 miles away and lock onto them at 12 miles. Like the J40 engine, however, the radars were slow in reaching Douglas, and not all Skyrays flew with that equipment; some spent their careers as day fighters, as their creators had intended.

The Ford’s foibles remained, but were not seen as insurmountable. “It had a lot of complicated restrictions,” says Abzug. “Get the thing rolling at high speed, you had to tell the pilot about restrictions. For example, at 400 knots do not exceed two-thirds aileron or one-third back stick. But there’s no way pilots can remember all that stuff. We resorted to placarding,” putting up the small warning signs that dot even Cessna cockpits with no-no’s for the pilot.

On an afternoon in 1955, Bob Rahn leapt off the Los Angeles International Airport’s runway in a production Skyray, heading out over the Pacific a hundred feet above the waves. The idea was to see whether enough pitch trim was available with the new engine to compensate for the airplane’s tuck-under at transonic speeds. He later wrote, “I had accelerated to Mach .98 (approximately 750 mph) in afterburner. This Mach speed created the maximum tuck-under. Full trimmer deflection was required to maintain trimmed flight. Therefore I concluded that the engineers had done a good job with respect to adequate trim for this low-altitude, high-speed flight environment. For all practical purposes, the test was completed. So I nonchalantly shut off the afterburner.”
The Skyray decelerated so rapidly that the trimmer became super-effective, flipping the nose suddenly skyward. “My Skyray and I were pitched up at a gut-wrenching 9.1 Gs,” Rahn wrote. “The airplane had a design limit of 7.0 Gs. Moreover, I wasn’t wearing a g-suit…. I immediately blacked out.” Rahn lost his vision but was aware of his situation. Reluctant to touch anything for fear of making a bad situation worse, he endured the ride. When his eyes cleared, his windscreen was all blue Pacific. “I was in a vertical dive after completing three-fourths of a loop.” Gingerly recovering at about 3,000 feet, he looked out at the wings. “They were wrinkled from wing tip to wing tip, resembling dried prunes.”
Back on the ground at LAX, Rahn found that the rest of the Skyray’s skin was wrinkled, the wings were incurably bent, and some of the vertical stabilizer’s stringers were protruding, like broken bones. The engine had torn off its mounts and was resting on the engine-compartment access door, pinching a fuel line. Later, Rahn reckoned that the event had been caused by the added thrust and the resulting increase in tuck-under. The corresponding increase in nose-up trim had made the Ford go nuts when it suddenly decelerated. Scratch one Skyray.

Even before the F4D entered production, the Navy had altered its mission. Instead of a day fighter, a role for which it had been exquisitely prepared, the Ford would now be an all-weather interceptor. Unstable and skittish by nature, the Skyray seemed a poor choice for such work, a thoroughbred tapped for hansom duty.

In April 1956, more than five years after the prototype’s first flight, Douglas began delivering Skyrays. In all, Fords went out to 11 Navy, six Marine Corps, and three reserve squadrons, with a few more going to specialized units.

But the Ford’s finest moment came not with the Navy, but with the Air Force.
The first unit to receive the Skyray, eventually reorganized as VFAW-3 (Fleet All Weather Squadron 3) and based at Naval Air Station North Island in San Diego, was the only Navy unit under the operational control of the North American Air Defense Command. It protected a southwestern wedge of U.S. airspace from unidentified intruders. Like Royal Air Force pilots during the Battle of Britain, the pilots of VFAW-3 slept in their flightsuits a short run from their aircraft.
“A claxon still makes the hairs stand up on my neck,” says David Dungan, a retired Navy captain. “We’d come out of there like a shot. They held all traffic, airliners, everything, when we launched. From a sound sleep to takeoff on Runway 18 within five minutes. Flying out over the black sea. By the time we were in the airplanes we were so adrenalined up” all thought of sleep was gone.
“We were really good. One reason, we had only second-tour pilots, no one fresh out of training command. We all had some experience. The Air Force demanded that we be able to operate at 200-foot ceilings, half-mile visibility. You needed some experience.”
“We did a lot of demo scrambles,” remembers retired commander James Berry, another VFAW-3 veteran. “When VIPs came to North Island we’d get hit with the scramble horn. We had five minutes to get airborne. We were usually in the air with two aircraft in about two and a half minutes.” Later he adds, “We were also sort of the apple of the Navy’s eye, winning Air Force prizes.”
Those prizes included the top interceptor titles in 1957 and 1958, flying against such faster Air Force fighters as the McDonnell F-101 and Convair’s delta-wing F-102 and F-106.

Dungan notes that in a fight, speed and better armament systems aren’t everything. “We carried 2.75-inch FFAR [folding-fin aircraft rockets] in a pod. I think the Skyray would have done fine in combat. You have to use what you have. You didn’t get into a merge fight with MiGs in the Phantom, you’d lose. The F4D, you could turn inside this room. There was also that acceleration.”
During the Cuban Missile Crisis, a VFAW-3 detachment took its Skyrays to Naval Air Station Key West to guard against intruders crossing the narrow straits. “We were flying three, four times a night down there,” says Dungan. “No lights, just black water. Like flying off a carrier. We had to intercept a lot of little planes.” Private pilots would wander into defended airspace, causing the Skyrays to scramble. “No sooner were we airborne out of Key West,” he says, “we could see the lights of Havana.”
“There were a lot of problems with aircraft coming up from the south and flight plans not being passed through Cuba,” says Berry. “We didn’t make contact with any MiGs, but we were vectored toward them and they turned back for home.”
As for piloting the Ford, “I loved it,” says Dungan. “I didn’t fly it onto a carrier, I flew it off the beach at North Island. It wasn’t the most stable airplane in the world. You had to hold onto it on landing, that’s for sure. The F4D rocked around a lot,” partly because the main gear deployed one leg at a time, causing the airplane to skid. “We’d make an approach to North Island at 3,000 feet for Runway 27. About the time they turned us on final, we dropped the gear. The airplane would move around—it was like standing on top of a pencil. Okay in VFR conditions, but not so good in IFR approaches.”
According to Gerald G. O’Rourke, a retired Navy captain with long experience in—and a low opinion of—the Ford, “The wings were large for the size of the plane, and altogether too efficient at producing lift at slow speeds. The vertical tail was too small and tended to get blanked out by the wings at the high angles of attack required for slower speed flight. As a result, the slightest disturbance induced by rough air or a rough pilot made the Ford swing from side to side on approach. As it did, the advancing wing increased its lift, the opposite one decreased its lift, and the plane started to roll…. Low-speed flight was really a series of wallowing, half-roll, half sideslip maneuvers that made the bird look drunk.” He called the airplane the worst Dutch roller in the fleet.

Loved or loathed, the Skyray was on borrowed time. In December 1958 production had ceased at 420 airplanes, and orders for another 230 were canceled.

Ed LeFaivre’s time-to-climb mark of May 1958 was snatched away that December by an Air Force F-104A. Bob Rahn’s record-breaking 100-kilometer run was among the last flown so close to the ground. But in February 1959, a French Dassault Mirage III stole that crown, albeit at 22,970 feet. In August 1961, McDonnell’s Phantom II broke Jim Verdin’s three-kilometer mark. VFAW-3 was decommissioned in April 1963 and the Navy bowed out of the continental air defense system for good. The Marines’ VMF(AW)-542, the last active-duty squadron to fly the Skyray, came home from Japan in November 1963. Even the phonetically evocative F4D designation disappeared, replaced by the F-6A tri-service nomenclature.

The oracles of aviation might have said that the end was discernible on May 27, 1958, just four days after LeFaivre became the fastest man to 50,000 feet. That was the date of the Phantom II’s first flight. “As soon as the Phantom came in,” says Erv Heald, “we were out of business.”
Well, not entirely. Douglas tried to sell a new, improved Ford called the Skylancer, a longer, more powerful Skyray without the warts. The test pilots liked the new airplane, but the Navy chose Chance Vought’s F8U Crusader. Because the Skylancer was never produced, the Ford earned one final distinction: It was Douglas’ last fighter.