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A Lockheed SP-2H Neptune of U.S. Navy Reserve patrol squadron VP-65 sorties from Naval Air Station Point Mugu, Calif., in 1973. (Lockheed Martin)

Sea Sentinel: The Lockheed P2V Neptune

By Stephan Wilkinson
5/18/2018 • Aviation History Magazine

Lockheed’s P2V Neptune served in Korea and Vietnam, searched for Soviet submarines and even carried nuclear weapons, but today is largely forgotten.

“It’s a pilot’s airplane. It has great handling qualities; it’ll do what you want it to do when you want it. It’s just a pleasure to fly.” 

“It” is the Lockheed P2V Neptune patrol bomber, and that opinion comes from Russell Strine, who flies the Mid-Atlantic Air Museum’s fully restored P2V-7 (which is currently inactive, since airshows can no longer afford the amount of fuel it burns).

“We didn’t get there fast, but we always got there,” says P2V-7 radioman Richard Boslow, who flew in Neptunes from 1965 through 1967. Richard Pickering started his patrol-bomber career flying the Consolidated PB4Y-2, the U.S. Navy’s single-tail version of the B-24, before spending 4,500 hours in four different versions of the Neptune. “I always felt that I was strapped to the PB4Y and that the P2V was strapped to me,” he comments.

“The P2V was very forgiving,” says Ron Price, a sonobuoy operator with 2,500 hours in Neptunes between 1962 and 1966. “The wings were flexible, which was a big help down low in turbulence. I remember I had to look up to see the stack on a Russian trawler.” The Neptune was designed to absorb the low-altitude turbulence that was inevitable during maritime surveillance and sub-hunting. Make-do patrol bombers such as the PB4Y-2 and the Royal Air Force’s Avro Shackle­ton were both based on airframes intended to fly at far higher altitudes.

“When we used to take our Neptune to airshows,” Strine says, “people didn’t know what it was. It’s a forgotten airplane.”

Indeed it is. Ask casual aviation enthusiasts to trace the history of the modern American bomber and they will almost certainly go full Boeing, with maybe a nod to the B-24: first the B-17, then the B-29 and B-50, leading directly to the B-47 and B-52. Few will remember that Lockheed had substantial skin in the game with the Cold Warrior P2V, which first flew in 1945 and remained opera­tional as a U.S. military aircraft until 1970: too late for World War II and ultimately overshadowed by its successor, the four-turboprop P3 Orion. The Neptune flew combat missions for the U.S. in two wars—Korea and Vietnam—and was one of the nation’s busiest aerial resources during much of the Cold War. The P2V’s last combat operation took place in May 1982, when an Argentine Neptune radar-guided a Super Etendard through a heavy overcast to sink the British destroyer Sheffield with an Exocet missile during the Falklands War.

A P2V-7 of VP-18 flies past the Soviet freighter "Okhotsk," searching for nuclear weapons during the Cuban Missile Crisis in October 1962. (Getty Images)
A P2V-7 of VP-18 flies past the Soviet freighter "Okhotsk," searching for nuclear weapons during the Cuban Missile Crisis in October 1962. (Getty Images)

The Neptune was manufactured nonstop from 1946 through 1961—one of the longest unbroken production runs of any military aircraft ever built. As Aviation History contributing editor Walter J. Boyne once wrote, “The Neptune signaled a new era in which aircraft became platforms for other technology and as such had a far greater longevity than ever before….Few aircraft have succeeded so well in doing so many tasks over such a long period of time.”

Early in its career, the Neptune was a heavily armed offensive weapon with turrets, a noseful of fixed 20mm cannons and a big bay full of bombs, torpedoes or depth charges. All but the depth charges were eventually shed, when it became clear that no Neptune would ever catch a Soviet nuclear sub on the surface. P2Vs were briefly used as gunships during the Vietnam War. Filled with expensive electronics, however, they were too vulnerable and valuable to risk as truck-busters.

Lockheed had produced about 9,000 medium patrol bombers for the Navy and the RAF during World War II—the Hudson, Ventura and Har­poon, all based on the twin-tail Model 14 Super Electra and its derivative Model 18 Lodestar airliners. The Neptune was Lockheed’s first all-new bomber. It was initially designed as a private venture of Lockheed’s Vega subsidiary in late 1941, but the exigencies of war prevented serious work being done on the project until 1944. The Navy needed proven aircraft, not an all-new design. The year after the war ended, Lockheed lost almost $22 million, and even more in 1947 and ’48. Con­sistent postwar orders for P2Vs, however, helped to keep the inevitable postwar slump manageable.

Lockheed designer/engineer Kelly Johnson played a key role in the development of the Super Electra and its offspring, but it apparently soured him on further patrol-bomber work. Johnson had a famous list of 14 rules for how his Skunk Works team of iconoclasts would operate. Those rules were published and public, but a 15th never made it into official print. “Starve before doing business with the damned Navy,” Johnson said. “They don’t know what the hell they want and will drive you up a wall before they break either your heart or a more exposed part of your anatomy.” So it’s not surprising that Johnson had no hand in the design of the Nep­tune, instead busying himself with the P-80 Shooting Star and the Constellation. The Neptune was the work of John Wassall, chief engineer of the Vega subsidiary, with the substantial help of engineers R.A. Bailey and Lou Height.

The P2V was a success straight out of the box. In 1946 the U.S. Army Air Forces was setting records routinely with B-29s, raising the bar by simply ferrying them nonstop from the Pacific back to the States. This annoyed Admiral Chester Nimitz, who knew the AAF was campaigning for the big budget bucks by claiming that long-range nuclear raiding was its bailiwick alone.

A Neptune patrols off Southern California circa 1959-1960. (National Air and Space Museum)
A Neptune patrols off Southern California circa 1959-1960. (National Air and Space Museum)

Nimitz suggested upstaging the Army by setting a record with the Navy’s brand-new Neptune. P2V-1 production aircraft number three was fitted with extra fuel tanks that increased its capacity to almost 9,000 gallons. The airplane was sent to Perth, Australia, with the goal of flying east nonstop and unrefueled all the way to Washington, D.C., maybe even on to Bermuda. Headwinds and bad weather dashed those hopes, but The Turtle made it as far as Naval Air Station Columbus, Ohio, setting a record of 11,236 miles that stood for 16 years, until an Air Force B-52H flew about 1,300 miles farther.

A Navy spokesman decided that The Turtle wasn’t a jazzy enough name for a record-setting bomber, so in a press release he bumped it up to The Truculent Turtle. Call it what you will, the airplane today sits in the National Naval Aviation Museum, in Pensacola, Fla.

The P2V went through a considerable range of variants, from P2V-1 to -7, with endless subvariants along the way. There was a P2V-8 on the drawing board, but it was canceled with the arrival of the P-3 Orion, the Neptune’s direct successor. (In 1962 the Navy redesignated P2Vs as P-2s, but to us the Neptune will forever be a P2V, just as a Mustang is a P-51, not an F-word.)

The Neptune grew in fuselage length as more and more sub-hunting and electronic intelligence gear was loaded aboard, including the characteristic tail-stinger extension to hold the magnetic anomaly detector boom. The fuselage was extended with a section inserted forward of the wing starting with the P2V-6. This was relatively simple to do, as the Neptune was designed for ease of manufacture, and the entire fuselage from just aft of the cockpit to the beginning of the tail cone is a straight-sided, uniform cross section oval can.

Throughout its Navy career, the P2V was powered by a pair of Wright R-3350 twin-row Duplex-Cyclone radials, which had proved troublesome aboard B-29s. But wartime experience had pinpointed the R-3350’s weak spots—mainly cooling problems and an improperly designed exhaust system—and the engine turned out to be reliable on the Neptune.

Most Neptune variants mounted straight R-3350s, but with the P2V-4, the Wright engines became turbocompounds—R-3350s with three power-recovery turbines that each added about 150 hp. The PRTs were essentially exhaust-driven turbocharger impellers, but rather than driving compressors, they imparted their torque mechanically, straight back to the crankshaft via shafts driving fluid couplings. (Horsepower figures for the R-3350 and its turbocompounding system vary substantially from source to source. The always-reliable Aircraft Engine Historical Society says that the Neptune started life with 2,400-hp engines and ended its career with 3,700 hp each.)

A far more substantial power boost came from the addition of two 3,500-pound-thrust turbojets in underwing pods on the P2V-5 and succeeding marks. The Navy had by this time loaded four tons of extra electronic gear aboard the Neptune, and the airplane could barely get off the ground. “I learned early on that the -7 is a four-engine airplane on takeoff,” says Russ Strine. “It does burn fuel going down the runway, nearly 2,000 gallons per hour, but you get off that power setting right away and then can throttle the jets back. Typically, I left them at idle until I got the recips cooled down, then I went ahead and secured them.” Strine kept the jets at idle during low-altitude airshow displays, but unlike Navy SOP, didn’t leave them running during landings.

Though it was hard to hear the jets inside the airplane, the R-3350s were another matter, thanks to a lack of any interior insulation. “The guys who flew Neptunes are mostly deaf,” says Richard Boslow. “Ninety percent of them wear hearing aids, and the other 10 percent need them. The patrols you didn’t look forward to were the ones where you were out in a patrol box in the middle of the North Atlantic in midwinter and you got a radio message ‘PLE,’ which meant fly to the prudent limit of endurance: Stay out until you have just enough gas to get home. We had one mission that went 15½ hours.” Sonobuoy operator Ron Price remembers that “We had gas heaters, but if we got even the slightest whiff of gasoline, we had to secure them. We did 10-hour flights without any heat.”

 

The Neptune is a big airplane. A casual glance at a photo of a P2V might have you thinking in B-25 terms, but the Neptune is bigger than a B-17 in every dimension and carried a larger crew—as many as 12 pilots, observers, weapons-system operators, a radioman, a navigator and other electronics specialists. The P2V also had a flight engineer, whose official title, oddly, was “plane captain,” but who was not a pilot. He sat in a jump seat just behind and between the pilots and was responsible for a variety of duties, including balancing the substantial fuel load.

Despite the size of the crew, it was almost impossible to bail out of a Neptune. The fuselage was studded with antennas and radomes, many of them close to the two bailout hatches—one below the flight deck and a second in the aft compartment. “The only way to bail out of a Neptune was the after hatch,” says Boslow, “and there were a number of antennas out there that could cut you in half. Or you went out the nosewheel well and hoped you didn’t face-plant into the radome.” Ditching was considered a better option.

Ditching was indeed part of the mission for the dozen P2V-2s and -3s that the Navy outfitted as nuclear bombers in the late 1940s. The P2V-3Cs, as they were designated, were supposed to take off from carriers and, assuming they somehow penetrated Soviet defenses and survived, return to ditch alongside the ships, since they had no tailhooks. The one concession to this maneuver was a “hydro-flap” that extended down from the belly forward of the wing leading edge, to help keep the nose up during a ditching.

These weren’t the only P2Vs armed with nuclear weapons. “Sometimes we carried nuclear depth charges,” recalls Boslow. “If you got within half a mile of a Soviet sub, you’d be sure of killing it. Of course you’d probably kill yourself too.”

Among the most unusual Neptune variants were the seven heavily modified P2V-7s redesignated as RB-69As and given Air Force markings. Like the U-2, Lockheed’s Skunk Works actually built them for the CIA as spyplanes. The “Sacred Seven” operated over both central Europe and mainland China from 1957 through 1964, and some of their pilots were civilians.

Though the RB-69As were capable of everything from leaflet-dropping to aerial delivery and retrieval (via Skyhook) of behind-enemy-lines agents, their main mission was gathering electronic intelligence. They called it “perimeter aerial reconnaissance,” the perimeters being the Iron and Bamboo curtains, and there were times when the RB-69As actually crossed those borders. The Chinese shot down five of the seven, and nobody seems to know what happened to the two survivors. An “RB-69A” is on display at Warner-Robins Air Force Base, in Georgia, but it is actually an ex-Navy P2V painted in Air Force colors.

The Army was the third U.S. service to operate Neptunes. Six P2V-5s, redesignated as AP-2Es, served in Vietnam as radio-signal snoopers and jammers. Robert Cothroll was a voice-intercept operator aboard one of those AP-2Es from May 1970 through 1971, working for the intelligence staffs of Army ground units. “We flew over the Ho Chi Minh Trail in Laos,” says Cothroll, listening to short-range tactical radio transmissions by the North Vietnamese Army. “We usually flew at around 130 knots, about as slow as we could. We made lazy ovals, never the same way twice. There was a lot of triple-A in the area, plus a couple of SAM sites. We weren’t shot at that often. One plane had a round go through a wing fuel tank,
but it exploded well above the aircraft. I think because we were passive—no armament—and were often with F-4s, they didn’t expose their gun sites to us. And they were holding their SAMs back for someone more important.”

One of four Neptunes converted in 1968 for ground attack as AP-2Hs flies a mission over South Vietnam. (U.S. Navy)
One of four Neptunes converted in 1968 for ground attack as AP-2Hs flies a mission over South Vietnam. (U.S. Navy)

One thing Cothroll particularly remembers about those 13-hour missions was that the Neptune lazed along in such a nose-high attitude that “Guys would complain that our buttocks were going to be disproportionate—one cheek bigger than the other—because we sat sideways and were always leaning slightly to the left.” Look at any side-view photo of a Neptune and you’ll see the substantial downward thrust line of the piston engines. This is an airplane that obviously was designed for loitering patrol flight, when the increased angle of attack would have put the engines at a normal attitude.

That side view also makes apparent one of the Neptune’s most distinguishing features: its oversize vertical tail. Some might assume the big tail fin was designed to enhance control during single-engine flight, but the rudder—the crucial engine-out control surface—is actually relatively narrow. The huge vertical stabilizer, however, creates great stability in low-altitude turbulence. “We got turbulence during monsoon season,” Cothroll remembers, “but nothing so bad you’d lose a cup of coffee. It was a pretty comfortable ride.”

“You have to be very aware of the crosswind component because of that big fin,” Russ Strine warns. “When you land and put the props into reverse, suddenly there’s no airflow over the fin, and the crosswind really grabs hold of it. They landed us at Oshkosh one time with a quartering tailwind. Jesus, what a scary episode that was. We lost control of the airplane momentarily and almost went off the runway. Went into reverse again and the airplane turned even harder, took out two runway lights.”

The Neptune’s tail featured an unusual “varicam,” a complex mechanism that altered the camber of the horizontal stabilizer, thus serving as an especially powerful trim tab but with lower drag. It was so effective that some pilots called it a super-elevator. The varicam helped trim out the varying center of gravity as Neptunes burned fuel on 10- to 13-hour missions, but its biggest benefit showed up during landings. 

P2Vs were typically nose-heavy, especially with a forward CG at the end of a long mission, and more than a few unwary pilots landed them nosewheel first, which led to up-and-down porpoising on the runway. Three or four porpoises usually resulted in the nosegear collapsing. Proper P2V landing technique was to roll on increasing amounts of nose-up varicam as the power came off in the flare. “It takes all the control pressures off, and you can hold the yoke back in your gut, and the nosewheel stays off till you’re halfway down the runway,” says Strine.

Another Neptune characteristic was its sometimes-leaky, high-pressure hydraulic system. “It’s a hydraulic airplane, no question about it,” explains Strine. “Everything is hydraulic except the cowl flaps: landing gear, flaps, spoilers, varicam, bomb bay doors…it’s a 3,000-psi system.” One story has it that when a pencil-size cockpit line sprang a tiny leak, a new Navy copilot tried to stanch it with his thumb. The spray of hydraulic fluid continued…through his thumbnail.

The Neptune’s swan song was as a firebomber, starting in the late 1960s. At one point there were 33 Neptunes operating as borate bombers in the West—a high percentage of the approximately 40 P2Vs that survived military service (not counting those left to molder away in the Davis-Monthan Boneyard). The last seven firefighters were retired in 2017, largely replaced by British Aerospace BAe 146s, which carry half again as much retardant and have a service life of 80,000 hours versus the Neptune’s 15,000.

Today there are only two restored Neptunes still flying. The Australian Historic Aircraft Res­to­ration Society operates a handsome P2V-7 painted in Royal Australian Air Force colors, and the Erickson Aircraft Collection, in Madras, Ore., regularly flies its -7 to airshows. Though the Mid-Atlantic Air Museum has grounded its Neptune, it could be relaunched after a thorough annual and some new tires and hydraulic and fuel hoses. 

Unfortunately, airshow crowds are far more interested in B-17s, B-24s and B-29s than they are in this forgotten bomber.  

 

Contributing editor Stephan Wilkinson suggests for further reading Lockheed P2V Neptune, by Wayne Mutza.

This article originally appeared in the July 2018 issue of Aviation History. Subscribe today!

  

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