Martin P6M Sea Master by Revell

1/136 scale
Kit No. 8621
Cost: $17.00
Decals: One version – U.S. Navy (appears to be reprint of original kit markings)
Comments: 1992 “History Makers” re-issue of original 1956 kit; raised panel lines and rivet detail, including raised lines for national markings

History

The Martin P6M SeaMaster was a revolutionary swept-wing, jet-powered flying boat that was also a strategic bomber designed to give the U.S. Navy a seaborne nuclear strike capability at a time when the Air Force’s Strategic Air Command threatened to crowd the Navy out of the business of nuclear weapons delivery altogether — and gobble up the lion’s share of Congressional appropriations for defense in the bargain.

In the early days of the Cold War, the Navy’s first bid for a piece of the strategic nuclear mission, the supercarrier USS United States, was killed by the Pentagon in favor of the Air Force’s B-36 bomber. In response, the admirals came up with a plan for a force of nuclear-armed seaplanes. The result was the Martin SeaMaster, and it very nearly entered service; production aircraft were built and Navy crews were undergoing operational conversion, with a service entry about six months off, when the program was cancelled on August 21, 1959.

The Seaplane Striking Force (formally called the Mobile Base Concept) would comprise jet-powered flying boats capable of long-range strategic nuclear attack and more mundane tasks such as conventional bombing, mine-laying, and reconnaissance. They would be protected by the smaller, supersonic seaplane fighter, Convair’s YF2Y-1 Sea Dart. From the outset, the Martin P6M SeaMaster (chosen over a competing design from Convair) was something of a contradiction in terms. Seaplanes need to be adept at low-altitude, low-speed flying—tasks not usually associated with high-performance jet engines — yet the SeaMaster also had to be fast enough to operate effectively as a strategic bomber. The prototype SeaMaster, designated the XP6M-1, flew for the first time on July 14, 1955. It featured four Allison J71-A-4 turbojet engines mounted in two nacelles on top of the fuselage near the wing roots.

For stability on the water, the wings, swept to 40 degrees, had a distinct anhedral—they drooped, allowing the wingtip tanks to sit on the water and serve as stabilizing floats, with no struts to induce drag. The SeaMaster’s truly revolutionary feature was its watertight hull — which nonetheless incorporated fully functional bomb bay doors in the plane’s belly — and its rotating bomb bay, allowing it to be re-armed through a dorsal hatch. Initial testing, conducted in secret on the Chesapeake Bay near Martin’s Baltimore headquarters, revealed that the jet exhausts were too close to the fuselage and scorched it when the afterburners were used. The Navy rolled the Sea Master out in November 1955, inviting the press to view the second prototype. After a demonstration flight, Chief of Naval Operations Admiral Arleigh Burke extolled the SeaMaster’s “beautiful performance.” The SeaMaster’s key feature, other than being jet powered, was its watertight, rotating bomb bay, which allowed it to re-arm with bombs or mines at sea via a dorsal hatch. This ability to operate from and re-fit in remote locations worldwide — literally any lake or river large enough to accommodate it, or the open sea — would give the Navy a highly mobile seaborne strike capability that would have been difficult for the Soviet Union to neutralize.

In December 1955, a control malfunction with the horizontal stabilizer caused the first prototype to break up in flight, killing all four crew members. Test flights of the remaining airplane resumed in May 1956 after modifications to the T-tail and installation of improved flight control and test instruments, along with ejection seats. Those would come in handy six months later, when the SeaMaster lost pitch control during a test flight and began vibrating uncontrollably. The crew escaped before the airplane broke up over the bay.

Undeterred, the Navy tested the YP6M-1 pre-production model, with the nacelles angled five degrees from the fuselage, and began refitting four old ships and a submarine to serve as SeaMaster support vessels. A beaching cradle enabled the Y model to get in and out of the water under its own power. Even New York Times military editor Hanson W. Baldwin, generally jaded when it came to Pentagon hype, was impressed by the aircraft’s “flexible operational capability, with the world’s oceans and lakes as its indestructible runways.”

The full-fledged production SeaMaster, the P6M-2, debuted in early 1959. It featured more powerful Pratt & Whitney J75-P-2 turbojet engines (with no afterburners), an aerial refueling probe, a rotating watertight bomb bay, Sperry navigation, flight control and autopilot systems, a high-visibility canopy, and a probe-and-drogue kit for conversion to a tanker. The added weight of the modifications made the P6M-2 ride lower in the water, eliminating the need for the wing anhedral.

The SeaMaster rivaled the Boeing B-52 in size, and in terms of sheer speed, outmatched its performance.

The new and improved SeaMaster could now give the Air Force a run for its money. Its top low-altitude speed, Mach 0.9, surpassed even that of the Strategic Air Command’s B-47 Stratojet and the new B-52 Stratofortress, which on the deck could do only slightly better than Mach 0.5. Naval aviators, readying for SeaMaster operations at a test area in North Carolina, were enthusiastic about the craft’s potential as a mine-layer: It would be able, they declared, to mine the Black Sea and attack Soviet submarines before they could leave port.

Just as all the bugs were being worked out of the SeaMaster, the advancing technology of the Fleet Ballistic Missile submarine (Polaris) rendered the entire concept of the Seaplane Striking Force superfluous, from the Pentagon’s point of view an inefficient and unnecessary expense. The Navy, struggling to justify the expense of continuing the SeaMaster’s development in light of Polaris, tried to sell it exclusively as a minelayer, but there were much cheaper ways to lay mines. The program’s numerous delays and redesigns were consuming funds the Navy urgently needed elsewhere. It did not help that the program to develop the Sea Dart, slated to be the SeaMaster’s fighter escort, had a murky future after a fatal mid-air explosion of the first prototype in November 1954, or that the Navy seemed to be leaning in favor of the Douglas F4D Skyray, its first supersonic carrier-borne fighter, from mid-1956 on. “The Navy has reduced its once hopeful Martin SeaMaster project rather drastically,” Hanson Baldwin noted glumly. An initial production forecast for 24 SeaMasters was cut to 18, then eight. In August 1959, having spent about $400 million, the Navy finally pulled the plug.

This flock of five SeaMasters, poised and ready to enter San Diego Bay with the aid of wheeled beaching dollies in 1958, underscores the Navy’s commitment to developing its fleet of seaplane strategic bombers. On the nearest aircraft, the angled turbojets atop the wing are clearly visible. Originally on a line parallel to the fuselage, the jet engines were angled outward about 5 degrees once it was discovered that the inboard afterburners were scorching the fuselage to the point that structural integrity was compromised.

Envisioned as a way to give the Navy a strategic nuclear force, the SeaMaster was eclipsed by the Polaris submarine program and the capability it gave the Navy to launch ballistic missiles armed with nuclear warheads from submerged submarines. Trying to make good on its considerable investment in the project, Martin tried to modify the SeaMaster concept into an eight-engine civilian airliner called the SeaMistress, and also toyed with the notion of a nuclear-powered flying boat and a supersonic seaplane. But none of these concepts caught on, and Martin left the airplane manufacturing business altogether to focus on avionics and weapons systems.

Despite its sleek lines and revolutionary design, its performance apparently superior to that of the Boeing B-52, the SeaMaster fell prey to a combination of poor timing, competing technology, and the inevitable guns-vs.-butter analysis employed to justify defense spending to this day. But for Polaris, but for the fact that all weapons systems have a price tag which government must decide whether it is willing to pay, the SeaMaster might have gone down in history as one of the great strategic bombers of the Cold War. But one thing is certain: being a seaplane, it would likely also have been one of the most expensive to maintain.

The Kit

Revell’s original 1956 box art for the Martin SeaMaster kit.

Revell’s P6M Seamaster dates back to 1956 and consists of 18 parts and a stand. Its raised panel lines and rivet detail betray its age, as does the lack of even a basic cockpit interior or bomb bay. At a minimum the raised lines for the national and U.S. Navy markings will have to be sanded off, although in 1956 they must have seemed rather cutting edge, as they facilitated the markings being painted on for those so motivated.

Although an old mold, the lines of the Seamaster appear to be generally accurate, from the T-tail to the four turbojet nacelles that as much as possible appear to be blended into the wing, particularly where the low, rectangular intakes meet its leading edge — a feature not deliberately incorporated into military aircraft design again until the development of stealth technology decades later. The single clear plastic part for the windshield may require some research, for it has no engraving of any kind to depict the framing. As is often true of Revell kits of this vintage, there is a small amount of warping, mainly of the fuselage halves, that will have to be overcome via hot water, tape, or good clamping devices, to assure a clean fit of the parts. A glaring omission of the kit is that it does not include at least some approximation of the SeaMaster’s key feature, its rotating bomb bay or the dorsal hatch used to gain access to it for arming. It is also worth noting that Revell did not arrange to update the decals, as they did in the case of the Martin Mariner. But a look at the two molds reveals that a great deal more care was put into the release of the Mariner just one year after the SeaMaster was introduced- perhaps because the Mariner, having entered service and remained in service for some 15 years, had an far larger constituency with definite, and likely higher, expectations of what the kit would look like.

Conclusion

The Revell SeaMaster kit, despite its flaws, remains notable for the revolutionary design the SeaMaster represented, as well as its historical interest as but one manifestation of inter-service rivalry during the Cold War. Highly recommended.

Reference

• “Cancelled: The Navy’s Seamaster” by Mark Wolverton; Air & Space Magazine, March 2012
• History Channel Broadcast: “Top Secret Weapons Revealed: The Seaplane Strike Force” – Original Air Date: March 2012