• Military Aviation

Tales of the F-14

More recollections of the fabled fighter.

• By airspacemag.com
• Air & Space Magazine, September 01, 2006

When the Grumman F-14 Tomcat flew its last mission in February, an era of naval aviation ended that we aren’t likely to see again. The F-14 is the heaviest—and probably the most famous—fighter ever to be catapulted from a carrier. Nothing in the fleet today can match the long reach of its radar or the clobber of the six Phoenix missiles it could carry.

For the magazine’s cover-story tribute, the editors interviewed pilots, radar intercept officers, designers, maintainers, and fans. Some of the stories wouldn’t fit even in 22 pages, so they’re included below, including a Grumman test pilot’s account of ejecting from the first production model of the F-14.

Bailout With 1.3 Seconds to Spare

Aircraft testing is a dangerous business, as test pilot Bob Smyth explained in a talk at the Cradle of Aviation Museum, Garden City, New York, on May 19, 2005.

“After Grumman’s Chief Test Pilot was killed in an F-111B takeoff accident in the spring of 1967, I was named the new chief test pilot.

The F-14 program promised to produce an airplane ready for first flight 17 months after contract go-ahead, which would be January 1971. As chief test pilot, I would make the first flight, and Bill Miller, our project pilot, would occupy the rear seat.

The F-14 program was led by a vice president who had previously spent years heading up the Preliminary Design Department. He was a very aggressive leader with a short attention span. It was his goal to fly a month earlier than the optimistic schedule had promised.

By December 30th, everyone was back (from a Christmas break), bright-eyed, and the weather was bluebird day. We were ready for our “real” First Flight, when we would go to altitude, sweep the wings, push out to Mach 1.2, and generally exercise all systems within the modest flight envelope allowed on First Flight and, of course, take pictures. (The First Flight, taking the Tomcat up and making a few simple turns, was made on December 21.)
By agreement, we would swap seats and Bill would sit up front. The weather was CAVU and cold, with about 20 knots of wind out of the northwest.

After takeoff we climbed to 10,000 feet, lest there be any hydraulic or mechanical mischief in the system. We had rounded Montauk Point and were headed back along Long Island’s south shore when we got to gear retraction entry on the flight card.

Immediately after raising the gear handle, our A-6 chase pilot said we were venting fluid out of the right side of the airplane. At the same instant, the combined hydraulic system gauge went to zero. Twenty-one gallons of hydraulic fluid had just left the airplane.

We started back to home base at 180 knots, our limit airspeed because the flaps were still extended. In about ten minutes, we were lined up with our runway about three miles out when we blew our gear down with the nitrogen bottle, since our flight hydraulic system only powered the flight controls.

At this time, our chase said we were venting more fluid, and our flight hydraulic system gauge went to zero. The airplane then went through about two cycles of gentle but uncontrollable pitching, and then snapped violently nose down.

At this point we were about a half-mile short of the runway, about 25 feet above the trees. Bill quickly initiated the ejection sequence using his face curtain. A sensitive accelerometer on the nose strut recorded and telemetered back to the ground the little blips showing the firing of the canopy and then the ejection guns on the two seats in turn. That all took 0.9 seconds as advertised; 0.4 seconds later the nosewheel hit a tree!
My Martin-Baker seat sent me staight up about 150 feet, but when Bill’s fired a split second later, it sent him forward, only gaining about 10 feet vertically. Both chutes deployed nicely, and neither of us was injured. Thirty minutes later, when the fire caused by 10,000 pounds of fuel was put out, the ground crew found two fractured 5/16th-inch-inner-diameter titanium hydraulic lines, one in each wheel well.

The F-14 had an all-titanium hydraulic system with an 84-gallon-per-minute pump on each engine with no accumulators, all in the interest of saving weight. Each pump had nine pistons, which were varied in output by a swash plate. As it turned out, each time one of the nine pistons did its thing, it sent a 200-300-pounds-per-square-inch pulse down the basic 3,000-psi system. Apparently, without accumulators to dampen the pulses, a resonance occurred which fatigued the lines. Engineering duplicated the failure on a full-scale mockup of the system in 1.2 minutes at just the right pump RPM. When the line was changed to stainless steel, the line failed in 23 minutes. The answer was not material, but proper forming and clamping of the line to prevent resonance. The second F-14 did not make its first flight until May 24, 1971. There were no hydraulic problems again on the F-14 program.

As an embarrassing postscript, this whole episode could have been avoided if we had not been in such a bloody hurry. During one of the all-night engine runs a few days before First Flight, I was running the engines under the lights during systems check at 2-3 a.m. when the plane captain started waving his arms to shut down the engines. I looked over the side and saw a large puddle of hydraulic fluid.

I asked what happened, and he said it must have been a loose B nut. Well, there was only a handful of B nuts on the airplane, since most of the hydraulic connectors were the super-dry Cryofit connectors. We were all sleepy, so we went home and thought no more about it.

We later found out that a report from the Engineering Lab was working its way through the system over Christmas, telling us that the engine run failure was a fatigue fracture of the 5/16th-inch titanium line.”

A Pinball Machine in the Cockpit

Vincent Devino was the head of cockpit design and avionics installation on the F-14 from the time Grumman proposed the design in 1967. See also Devino’s photos from that era.

“The company felt very confident that it would win the contract. It would have been foolish for the Navy to do otherwise at that point because we’d had the experience integrating the AWG-9 radar system that Hughes put together on the F-111B. We took the F-14’s system right out of the F-111B.

In designing the cockpit, we worked with the project pilot who went through system by system with each of the engineers in order to whittle down the number of discrete controls in order to justify every one that the engineer thought was necessary. In the flight control system the number of caution and warning indicators was reduced. Some of the engineers wanted a first level warning of every first level system, but we simplified the number of cautions and warnings. The objective, among other things was that it was a Navy airplane and the Navy didn’t want a pinball machine in the cockpit. They didn’t want a pilot being distracted while he’s being shot off the catapult.

Since the airplane was capable of a long-endurance mission—six hours in the airplane—we tried to make the cockpits comfortable. If you’ve ever sat on an ejection seat, it’s like sitting on a brick. We made use of tempurpedic foam-the same stuff they’re yaking about for mattresses. We had people sitting in the mockup for 6 to 12 hours in the configuration that we intended to produce, so we wound up with a comfortable cockpit.

Packaging some of the stuff to fit the narrower contours of the F-14 was a challenge, but we never wound up with boxes left sitting on the desk. When you package a fighter, if you have any voids in the airplane you didn’t do your job right.

The canopy would have been made out of one piece but we couldn’t find anybody who could make a big enough piece of plexiglas at the time.

Integrating the head up display was a problem. Given the technology at the time, it was a huge box: the optics were about ten inches in diameter. Being able to fit the reflector plate under the windshield at an angle that would avoid double images was tough. The line of vision is collimated at infinity. The symbology is off in the distance it you don’t know have the HUD and windshield matched correctly: Targets could appear to be where they are not. The HUD has a flat reflector plate, and you end up with refraction problems that can cause double images if the curvature of the windshield is not correct.

We gave the F-14 a flat windshield as opposed to the F-15’s single curvature. A flat window fit into the windshield gave more ballistic protection; it was more bullet-proof than the two side shields.

We got it right because somebody else had made the mistake before we did. The F-111 had a sharply raked windshield for aerodynamic reasons and it created problems. The F-14 windshield is raked at only 30 degrees so you don’t reflect more of the light coming in than you refract. It’s a pull and tug operation: The aerodynamics guys would like no windshield on the airplane. They’d like a bullet. Then we come along and put a bump there.”

An F-14 Every Week

Bob Klein, vice president of logistics and technology at Northrop Grumman, was the company’s last chief engineer of the F-14 program. He worked on an assembly line while in high school, in 1974.

“We built an F-14 once a week. Grumman had a program that took two scholarship winners, and if you were studying engineering you’d work in production for one month, seeing how airplanes are put together. I learned more in that one month (on the assembly line) than in the rest of my career.

We took an F-14 and instrumented it, flew it, and compared (fatigue measurements) to fleet data. We found it had 20 percent more life left in it. We saved the Navy $250 million, and added another life to the nine lives of the Tomcat. Well, I guess it was two lives, since it was 20 percent.

We had this great 8-inch by 8-inch display in the back seat. With that and the (Lightning) pod, the F-14 could carry a 2,000-pound weapon. It became the number one choice for fleet missions...We implemented the Lightning pod, laser-guided and GPS guided weapons very quickly. We went from turning on the pod to implementing it in the fleet in six months...The best way to do something ‘lean’ is to gather a tight group of people, give them very little money, and very little time.”

Like Sitting in a Cadillac

Charlie Brown, a Vietnam-era combat pilot who flew Bearcats and two years in Phantom IIs, was part of the F-14 design team as well as an experimental test pilot with Grumman.

“The [Navy] specs called for Mach 2.34. We actually tested the airplane for Mach 2.5. I flew it 2.5 a couple times. When you fly a Phantom, it’s built for 2.0, but when you fly that fast you know it. It’s like sitting on a beach ball; you don’t know which way it’ll go, it’s so sensitive. In a F-14 it’s like sitting in a Cadillac. It’s solid. You don’t realize you’re going that fast.

On December 30, 1970 Grumman took its new warplane for its second flight. It ended in a crash, and accusations were made regarding the choice of materials.

They wanted to get it in the air that year. The first flight [lead pilot] Bob Smyth and [project pilot] Bill Miller were going to takeoff, circle the field and land. I think it was a 35-minute flight. For the second flight, they took off and they got into the operations area and were testing, and the chase pilot recognized a loss of hydraulic fluid, being red and streaming on the airplane or streaming off the tailpipe. They proceeded to lose system after system...At 100 or 200 feet from landing the airplane went full nose down so they punched out. What happened was simple and understandable. Before you put up for first flight you put it through systems mockup and ground testing for vibration and things.... A short time before flight the flight test department decided they needed a parameter to check hydraulic pulsations in the system. We used titanium lines to lighten airplane instead of tried-and-true aluminum.... They connected a pressure sensor somewhere around the pressure pump. It was this line that failed. The configuration had not gone through the full ground test workup with the rest of airplane and systems. This small line was not clamped adequately and the vibration of the second flight was enough to crack the line. The whole titanium system was badmouthed for failing, but that’s not what really happened…

“The physics of getting supersonic air into the engine required rectangular air inlets. The engine only accepts subsonic air, or it’ll stall. How do you slow that air down? With moveable ramps. Hydraulic pistons move in such a fashion to slow air down as it goes to the forward compressor section of engine. These are computer-controlled. The air coming to the engine also has to have a fairly smooth flow, particularly with the TF30 engine from the F-111B program [which was sensitive to airflow disturbances and rapid throttle changes]. To get the airflow down in high Mach and maneuvering situations...was another challenge to the inlet designers. It was a challenge and we handled it…

“The F-14 was crafted to win dogfights. The tools it had for this mission were ideal at long and short ranges…

“The Tomcat’s air-to-air weapons mix was just unmatched. The Phoenix gives you up to 110-mile range. It launches and...[after a programmed number of feet] the missile turns on its own radar where told to look. It was a launch-and-leave situation. You can launch six and track more than 30 targets. One step down was the Sparrow, at 20-25 miles. Then you step down to infrared sidewinder. Now you’re talking feet-you’ve got that 25-mm gun, with about 600 rounds of ammo, so you have a full minute of firing time.

It was sort of a fighter pilot’s dream on an intercept [mission]. That capability has not been matched, and won’t be. We don’t have it anymore.”

Early Attempts at Swing Wings

All variable geometry wing aircraft are descendants of two experimental airplanes built on opposite sides of the Atlantic in the 1940s and 1950s.

The first is the Messerschmitt P 1101 a prototype airplane built by the Nazis that ranks as the first variable geometry jet fighter in history. It was found in May 1945 when a company of U.S. infantry seized a secret research laboratory in Oberammergau, a German town in the shadow of the Bavarian Alps. The design allowed its wings to be set at three angles on the ground to evaluate the reduction in drag and increase in speed in wind tunnels and, the Germans hoped, in flight tests. The wings could not morph in the air, however. It never flew.

It still made an impression. Robert J. Woods, the leader of a military intelligence unit called a Combined Advanced Field Team, evaluated the find, and later became co-founder and chief designer at Bell Aircraft Corp. He collected the identities of the experts who created the airplane and sent them, and the prototype, to America.

Woods convinced fellow management at Bell that the design had merit, and his efforts culminated in the 1951 first flight of the X-5, an experimental craft used by the U.S. military. Parts from the German airplane were cannibalized to create two X-5s. The X-5s were used to test wing angles, not as a prototype of a finished, operational variable wing aircraft. Unlike the 1945 model, they changed their wings while in flight, the first airplane able to do so. The research was later used to create the F-14.

Legendary British aircraft designer Sir Barnes Neville Wallis made a stab at swing-wing history and missed. Immediately after World War II he took the swing-wing concept and tried to make the idea functional. Working in the late 1940s, he experimented with a host of swept wing concepts he dubbed the Wild Goose. These included hand-launched designs and radio controlled aircraft capable of 100 mph speeds. Each had swept tail fins at the end of slender, laminar bodies. He tried the swing-wing concept for a civilian market with the Swallow, to be incorporated into a long distance airliner. The Swallow had a flattened fuselage that increased the lift of the wings. Models of the design flew in the mid-fifties and a 6-foot supersonic model broke Mach 2.5. The U.K. killed the program and Wallis tried to pitch the idea to America. According to the Barnes Memorial Trust, operated out of the Yorkshire Air Museum in Britain, Wallis commented that he “convinced the Americans too sincerely that this was a great idea, and so they decided to take it up for themselves instead of paying us a grant to do it in England.” None of his swept wing designs survived to production.