Sidebar: The Langley Water Lander

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A diagram of the Water Lander if it were full sized, as opposed to the one-eighth scale model that was built. Note the curvature of the wings as seen from the front, not coincidentally like the hull of a boat. Public domain image via NASA from Model Investigations of Water Landings of a Winged Reentry Configuration having Ourboard Folding Wing Panels. Click for a larger view.

There are two fundamental dichotomies in spacecraft design (or three, if you count the types of fuels used for their rockets). You have ballistic capsules in opposition to winged craft/lifting bodies, and you have water landings as opposed to coming in on solid ground. Three of the four possible combinations have been used by crewed spacecraft but one hasn’t: a water landing of a winged vehicle.

That’s not to say it hasn’t been examined, though. NASA studied the ramifactions of an emergency ditching of a Shuttle Orbiter (conclusion: a lot of damage to the underside, but it would stay afloat for a while as long as the wings weren’t badly holed), and the Australians famously photographed the USSR retrieving a BOR-4 test article from the Indian Ocean in 1983. Even earlier, the American ASSET, originally conceived for testing the alloys earmarked for the X-20’s heat shield, splashed down off Ascension Island after a suborbital jaunt from Cape Canaveral.

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The Water Lander model in its tank. Public domain image from same source as previous. Click here for a larger view.

As far back as 1959, NASA was testing the concept using a water tank at Langley Research Center in Virginia. They had a chicken-and-egg problem, though. How do you build a water-landing spacecraft without tests to tell you what it will look like? But then how do you do the necessary tests without having it built first? Ultimately they had to just go ahead and build it based on first principles and common sense. What they came up with never had a name, so for convenience’s sake we’ll call it the Langley Water Lander.

The re-entry vehicle they posited was a light one, just 3600 pounds (1.6 tonnes), which is only a few hundred pounds more than a Mercuty capsule. Given that much of it was wings, it would have definitely seated only one astronaut, perched in a slim fuselage.

And it really was a lot of wing for its size, 27 feet from tip to tip and with an area of 263 square feet (7.0 meters and 24.4 square meters); it had no tail at all, though it did have a large vertical fin. The wing was gently curved, making a cross-section something like a boat so that the craft could rock from side to side on the surface of the water without the tips of the wings dipping below the surface. This was made even more unlikely by the fact that the wingtips were designed to fold up once the craft had gone subsonic.

On its underside were two retractable 4.7-foot × 0.67-foot (1.4m × 0.20m) water skis and a smaller triangular skid aft, roughly a foot to a side, for drag; this was found to be more stable during the final run-out than anything involving a single nose ski.

Thus configured, a one-eighth scale model was built and tested, with the conclusion that the landings were not so bad at all. The Water Lander wasn’t too sensitive to a little yaw in the touch-down, and even with small waves (eight inches high and fifty feet long, or 20 cm and 20 meters,to scale) the run-out was only three to four hundred feet with a maximum of 5.1 g deceleration. On smooth waters, it came in at under 3.0 g and 100 feet further travel after touchdown.

The Water Lander was never intended to be built for actual use, but rather was a reflection of where NASA was in late 1959. They examined a great many basic possibilities for the crewed space program, many of which have fallen into obscurity. In the case of winged water landers, the reason likely was that there’s no advantage to them. A ballistic capsule, almost uncontrolled, can benefit from a target as big as the South Pacific Ocean. But the whole point of a winged re-entry vehicle is that it can be directed once in the atmosphere, and if you can do that you might was well direct it towards a runway.

Source

Model Investigations of Water Landings of a Winged Reentry Configuration having Ourboard Folding Wing Panels, William W. Petynia. Langley Research Center. December 1959.

The Martin 410: Apollo of Santa Ana

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A cutaway view of the Martin 410 as it would have been configured en route to the Moon (excepting the escape tower, at left, which would be ejected after launch). Note the lifting body shape of the crew compartment, and the stubby cylinder of the habitation module enclosed in the larger toroidal equipment and propulsion module. Image from Glenn L. Martin Company’s “Apollo Final Report: Configuration” delivered to NASA in 1961. Click for a larger view.

What it was: One of several formal proposals made to NASA in 1961 as part of the design competition for the Apollo spacecraft. It had certain similarities to the one that was actually built (as did all of the proposals, as they had to meet criteria set by NASA) but was primarily different in two ways. As Apollo was still pictured as a direct descent mission at the time, it didn’t use the Lunar Orbit Rendezvous technique that was used for the real missions, and the re-entry vehicle was a lifting body instead of a ballistic capsule.

Details: On October 9, 1960, fourteen different companies answered NASA RFP-302, which asked them for feasibility studies on advanced manned spacecraft for the upcoming Project Apollo. Among them were Lockheed, Boeing, General Electric, and Grumman, as well as the subject of this post: the Glenn L. Martin Company of Santa Ana, California.

Within two weeks the contest was down to three: GE, Convair, and Martin with what they called their Model 410. Up against the contractors was an internal design by NASA’s Langley Research Center, specifically their Space Task Group, which had designed the Mercury capsule. Time passed and with the agency buoyed by the first successful American manned spaceflight on May 5, 1961—Alan Shepard’s Freedom 7—May 17 saw the final proposals for all four on NASA desks and the process of evaluating and deciding between them underway.

Eight days later John F. Kennedy challenged Congress to achieve “the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth”, and things changed—the White House had had its interest piqued back in October when the study contracts were awarded and had been working behind the scenes with NASA. The Langley group rapidly metamorphosed into the much-larger Manned Spacecraft Center—now the Johnson Space Center—and by September started the move to land in Texas donated by Rice University (which is why Kennedy’s second famous space speech, the “We choose to go to the moon” one, was made there).

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The suggested layout of the Apollo spacecraft for the second phase of the competition. Note the considerable similarity to what actually got built. From Chariots for Apollo: A History of Manned Lunar Spacecraft. Click for a larger view.

Even before then, the Langley group had swung into action. Their chief engineer was Maxime Faget, an American of Belizean birth, had designed the Mercury capsule, and his head of engineering (Canadian Jim Chamberlin, formerly of Avro) was in the middle of designing the Gemini. Their job was to synthesize what the contractors had developed with their own design and use it to develop a new set of specifications—in actuality, a nearly complete design of its own—that could meet Kennedy’s challenge. While the three previous contractor proposals had been paid for by NASA to the tune of US$250,000 apiece (though all of them took a loss, spending in excess of $1 million apiece), the other contractors had been encouraged to carry on with their work on their own. This attitude now paid off: a new competition was begun for a final design, open to all groups who’d tried back in October not just the three previous winners. On July 28 twelve contractors (two had dropped out back during the first phase, Cornell and Republic Aviation) were asked to submit again based on the new prerequisites. Several of the contractors teamed up with each other, reducing the number of replies to five, but Martin once again went with the M-410 on their own.

Not counting the rocket adapter ring (which all the proposals had so they could mate to the upper stage of a Saturn), the M-410 was made up of three parts: a command module for use any time an engine was burning and for re-entry, a mission module in which the crew would live at other times, and a composite equipment and propulsion module.

The command module was the most interestingly divergent component compared to the Apollo spacecraft that actually got built. All three contractors evaluated ballistic, winged, and lifting body re-entry vehicles. The latter was a particular one NASA called an M-1, and Martin went above and beyond by evaluating a number of other shapes in all three categories before settling on a variation of the M-1. Their solution made the M-410’s re-entry moderately controllable, especially as it would have had four control flaps; Martin considered this a big improvement on Mercury or the Soviet Vostok. It would have been built out of aluminum alloy, and had a composite heat shield made out of ablative material and a superalloy (undecided at the time, but something like René 41 or an Inconel). The version of the M-410 submitted post-Kennedy’s speech was also unusual because of the four rectangular flaps that would deploy from its underside, which would expose solar panels to power the craft. During launch the command module had an emergency escape tower perched on top of it, though this would be jettisoned on reaching 90 kilometers in height.

The three crew would live for the majority of their mission in the mission module. This supplied a little over eleven cubic meters on top of roughly the same for the command module (contrast this with the 12.9 cubic meters of the combined Apollo Command Module and LM).

These two were then mated to the equipment and propulsion module. As well as the usual electronics for a Moon-bound manned spacecraft, it packed a single LR-115 engine (a design which later evolved into the R-10 and derivatives used for the Saturn I and the Centaur) and 4740 kilograms of liquid oxygen and liquid hydrogen.

Having launched in an unspecified way (NASA was still trying to decide if they were going to use multiple smaller rockets to establish a fuel depot in orbit, or go as they actually did with a larger rocket like the Saturn V), Martin suggested that the M-410 be sent on its way to the Moon using a lower stage attached to the rocket adapter ring. This stage would have contained roughly 13 tonnes of LH2 and LOX and been pushed by three LR-115s.

This was powerful enough to get it down to the Moon, because the entire thing was designed to land there. Exactly how this was to be accomplished remained to be seen, as NASA was then in the middle stages of its most historic argument: land directly via an Earth Orbit Rendezvous profile, or send a separable landing module and rendezvous above the Moon. Going in to the proposal period it was assumed that the former was likeliest, though the contractors were asked to consider what they would have to do if the latter won (as, of course, it did).

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One of the ideas studied, but explicitly rejected, for giving the M-410 artificial gravity: spin it up using the booster stage as a counterweight. From “Apollo Final Report: Configuration“. Click for a larger view.

Assuming it did land directly, though, the lower stage would be left behind as the propulsion module had sufficient thrust to lift itself back off the Moon and home to Earth. One thing the lower stage would not be used for was the generation of artificial gravity—Martin took the time to figure out if it were possible to generate a bit of it during the mission, including putting the lower stage out on a tether and using it as a counterweight to spin up the rest of the craft. They decided that for a trip as short as one to the Moon it wasn’t worth the extra weight needed for systems that could pull the trick off.

At the end of the mission, the command module would separate from the rest of the craft and re-enter. The M-410’s CM lifting body was designed to touchdown on water or land, with a combination of parachutes and retrorockets slowing it to just one meter per second as it touched the ground.

What happened to make it fail: On October 9, 1961 the new proposals were received, and two days later the five competing contractors gave presentations on their work. The evaluations began immediately thereafter, and were completed on October 28th. At the end of the competition, the M-410 was first with an average score of 6.9 points in each of the categories that NASA had outlined. Next came General Dynamics and North American Aviation, tied for second with 6.6 points; the GE-led and McDonnell-led contractor coalitions were the also-rans.

Despite the win Martin lost the contract to North American on November 28, 1961; NAA would go on to build the actual Apollo CSM. NASA administrator James Webb and his deputy Robert Seamans justified their decision on the basis of an external factor: NAA’s experience building the X-15.

The real reason is widely believed to be that North American had made the conscious decision to stick as closely as possible to Max Faget’s post-synthesis Langley design, and that NASA wanted that regardless of the merits of any other approach. Faget reportedly had been annoyed by the fact that none of the three initial designs had gone for a blunt-body re-entry vehicle, which was why he had come up with the Langley design in the first place and then convinced the agency to re-open the competition. He then had enough influence to disqualify any bid that didn’t follow his lead, including the Martin 410.

From this point onwards (and most noticeably in the proposals for the Space Shuttle a decade later, excepting the oddball SERV) NASA contractors understood that the implicit rule in any spacecraft design competition was “What Max Faget wants, Max Faget gets”. Despite the obvious possibilities for disaster with this approach giving him a veto turned out to be a pretty good idea: history has proven Maxime Faget was a talented spacecraft designer, arguably the best ever.

What was necessary for it to succeed: Not an awful lot more than what actually happened—the M-410 is one of the likeliest “what-ifs?” of the Apollo program.  It won the Apollo design competition, and if a small number of people (Faget, Webb, and Seamans) hadn’t been able to shift the results arbitrarily, it would have gone ahead. There would have been changes made, as happened in the real world to NAA’s design between 1961 and the first completed Block II Apollo craft flown in October 1968, but otherwise this design could have gone to the Moon.