Sidebar: The Tupolev OOS

clean

A model of the OOS shuttle, believed to be from a Russian magazine in the 1990s. If you have more information about this picture, please contact the author.

During the 80s the USSR’s space program stayed remarkably focused on Energia/Buran and the Mir space station, especially when compared to the infighting that marred the years 1966-1975. It fended off or adapted to a number of distractions, whether it was Vladimir Chelomei‘s repeated attempts to regain his previous, short-lived position on top of it, or airplane design bureaus suggesting anything from conservative alternatives to the recently discussed Myasishchev M-19 nuclear scram/ramjet.

The OOS was a late Soviet-era shuttle proposal from the Tupolev bureau, an also-ran in that country’s space business despite a strong position in civil aviation and strategic bomber development. Proposed as a fully reusable replacement for Buran sometime around the year 2000, it was about the same size as that craft or the American Space Shuttle, though somewhat heavier at 100 tonnes when fuelled. With a crew of two cosmonauts. it had a payload of 10 tonnes to and from low-Earth orbit.

If you’re a long-time reader of this blog, or just sufficiently into spacecraft, you probably slotted the shuttle pictured above toward the conservative end of that spectrum. Apart from the more-rounded contours, it looks to be much like the Shuttle, particularly in the shape of the underside. There, too, we have the usual ceramic tiles for dissipating the heat of re-entry. The engines are not visible, but I can tell you that there were three, burning LH2 and LOX during the ascent to orbit (though, curiously, switching out the hydrogen with kerosene for orbital maneuvers). Knowing that would likely not change your opinion at all.

Given that it’s was to be fully reusable, the ten-tonne payload mentioned earlier may have got you wondering, though. The actual American and Soviet shuttles had payloads in the 25-30 tonne range, so alright—there’s clearly some sort of tradeoff there. You’d be well-advised to wonder about the rest of the OOS’s configuration. Side boosters but no external tank? Perched on a reusable rocket in some manner, maybe?

Well, no. “OOS” stood for Odnostupenchati Orbitalni Samolyot, ‘one-stage orbital plane’, But a single-stage-to-orbit craft the size of the Orbiter? Surely that’s not possible.

This goes to show that you don’t think like a Soviet aircraft designer circa 1989. The OOS was to have been air-launched, and the other half of the system was the Antonov AKS:

AKS

Aerospace aficionados will remember that the An-225, which was used to piggy-back the Buran shuttle around the Soviet Union, was by most measures the largest aircraft ever built. This is two of them, one wing apiece removed and replaced with a sort of aerodynamic bridge, and then 675 tonnes of spacecraft and rocket propellants attached to its underside. It had twelve turbojet engines for when it flew without the orbiter attached (the dark circles in the diagram above, at lower right), with a supplementary ten more being added during launch operations (the white circles). The Aristocrats! With a length of 83 meters (272 feet), a wheelbase of 40m (131 feet) and a wingspan of 153m (502 feet), the combination came in at a whopping 1650 tonnes. By contrast, a fully fueled late-model 747 has a maximum takeoff weight of just under 440 tonnes.

There has been only one successful air-launching system in the world to date, Orbital ATK’s Pegasus. It weighs 23.1 tonnes and can put 0.44 tonnes in orbit; it’s launched from a Lockheed L-1011, already getting into the neighborhood of large airplanes. So start with some skepticism that 20 times this in launch mass and payload are a possibility for the late-era USSR.

Further, I haven’t (unfortunately) been able to find a detailed description of the AKS/OOS’s mission profile. I’d like to see it because I’m having a hard time picturing what the moment of separation would look like. Or rather, I have an image of the support crew aboard the AKS bouncing around like ping-pong balls in a boxcar once the plane, straining to get the orbiter to altitude, suddenly cuts loose 675 tonnes. For that matter, the OOS would have to light its engines pretty quickly thereafter or defeat the purpose of an air launch. As these were in the same class as the RS-25’s on the American Shuttle—the noise aboard the AKS, now presumably not all that far above and behind it, would have been intense.

I’m on record for my begrudging appreciation of the come-what-may technological megalomania that gripped the superpowers post-WWII. The US grew out that uncritical mindset after Love Canal and Three Mile Island, while the Soviets carried on until 1989. That extra time coupled with fossilized technocrats in charge allowed awe-inspiring audacity in technology of it to grow even greater than it did in the West.

Even so, I can’t imagine anyone with the power to make the Tu-OOS happen actually doing so. It would have been an immensely expensive and difficult project right at a time when the Soviet Union was in no position to take one up, and technological limitations would have prevented anything like it at an earlier point in that country’s history. The OOS/AKS was a paper project, and would have remained so.

Sources:

OOS, la bestia de Tupolev y Antonov

OOS, el sistema espacial de lanzamiento aéreo definitivo

Artist Vadim Lukashevich has numerous renders of the AKS/OOS combination on Buran.ru (screll down to the second half of the page).

Readers will note a lack of primary sources here. I’m convinced of this project’s existence, but any pointers to a source that’s a little more direct than what I’ve relied upon here would be most welcome.

 

The Douglas ASTRO: An Air Force Launcher

douglas-astro

The ASTRO, as pictured in the September 3, 1962 issue of Missiles and Rockets. Image artist unknown and copyright status uncertain, but believed to be in the public domain. Via the Internet Archive.

What it was: A lifting body craft proposed to the USAF by Douglas Aircraft. It would initially be used as a suborbital trainer then, after up-scaling and being paired with a second lifting body in an unusual nose-to-tail arrangement, evolve into a fully reusable vehicle with a nine-tonne payload capacity to LEO.

Details: In late 1962, the USAF was on the cusp of deciding how it would go forward with its plans to put military men in space. The X-15 had made its first flight mid-year, and the X-20 program was ramping up. Doubts about the latter were getting stronger, though, and would ultimately result in the Air Force deciding to work on the Manned Orbiting Laboratory instead.

It was at this point that an article was published in the now-defunct Missiles and Rockets magazine outlining a proposal from Douglas Aircraft that was supposedly being evaluated by the USAF. What it outlined was a two-part development program that would check the usual laundry list of military applications for space as perceived in the early 1960s.

The core of the ASTRO (Advanced Spacecraft Truck/Trainer/Transport Reusable Orbiter) was the answer to a question the USAF had proposed to North American Aviation and Douglas, as well as Boeing, Vought, and Republic: how to train pilots for the X-20 on actual flights prior to the X-20 being built. North American had come back with what they called the STX-15, which was a way of reconfiguring an X-15 to have the projected flight characteristics of an X-20 (except for, of course, the highest speed and orbital parts). The Phase I of Douglas’ ASTRO was their significantly more ambitious counter to the NAA proposal.

astro-schematic

A schematic of the ASTRO’s A2 vehicle, which would be both independent for suborbital hops, or be boosted to the point that it could be lifted into orbit by a derivative of the same vehicle. Note the booster nose’s ghostly presence at the far right of the image. Same source as previous. Click for a larger view.

Unfettered by the previously existing X-15, Douglas wanted to build a completely new craft dubbed A2, which would be capable of suborbital hops of about 5000 miles (8000 kilometers) after taking off from a runway under the impetus of a J-2 engine, the same rocket engine used by the Saturn V’s second and third stages. Pilots would get their space training, the USAF would have themselves a reusable vehicle with intercontinental range which could carry ten people, or a similar amount of payload. Two RL-10s, as used on the Centaur, would provide a little extra oomph.

Phase II was where Douglas diverged from the question being asked. Take the A2, modify it so that it only carried one crew and two extra J-2 engines, then stick it nose to bumper on the end of another A2 built to the Phase I spec. Turn it 90 degrees and launch it vertically, with the two separating from each other at altitude and speed (both unspecified). The sole crew member aboard the booster would glide back to Earth, while the uppermost A2 would ignite its engines, hopefully after allowing a bit of distance to build from the booster, and carry on into orbit. Douglas projected two crew and about a tonne of cargo to LEO in this configuration.

Phase III scaled up the booster, now dubbed B, and equipped it with two J-2s and one M-1, a never-built LH2/LOX engine that dwarfed even the F-1 engines used on the Saturn V’s main stage. Also launched vertically, this would be the ultimate version of the craft.

The full, two-stage Phase III vehicle was to have been 159 feet long (48.5 meters) and while mass was not mentioned the propellant capacity of the stages (165,000 pounds for the A2 and 594,000 pounds for the B) are—this suggests a total loaded vehicle mass at launch of about 380 to 400 tonnes. Total payload, as mentioned previously, was about nine tonnes, including crew, and there’s a sign that Douglas was nervous about this: the article specifically mentions wanting to launch due east from the Equator, which is an odd thing to be suggesting in 1962, well after the US had committed to launching from the continental USA.

If built, the program was expected to run from 1964 to 1970, with the first flight of the Phase III craft at the end of that period.

What happened to make it fail: It’s difficult to fit the ASTRO into the chronology of the X-20. Phase I appears to have been an attempt to come up with a “Gemini” for the X-20’s “Apollo”, giving the USAF the capability of sending pilots on long suborbital jaunts to train them for the environment they’d encounter when aboard the fully orbital X-20. Phase III would then have been a follow-up to the X-20, increasing crew capacity and payload over that craft.

If this is the case, then, it explains why the ASTRO never went anywhere. The craft made its sole notable public appearance in September of 1962, and American Secretary of Defense Robert McNamara was definitely thinking about cancelling the X-20 no later than March 1963—and possibly earlier. When the X-20 was stopped, then ASTRO would go with it. This is particularly true if one assumes, as seems likely, that the USAF was never very warm about the idea at all, and that it primarily existed as a pitch from Douglas leaked through Missiles and Rockets magazine to drum up support. There’s essentially no reports or discussion of ASTRO post-dating the magazine’s unveil.

What was necessary for it to succeed: It’s not easy to see a way forward for this one. X-20 was dead in the water less than six months later (eventually being formally cancelled in December 1963), and the payload capacity of even the Phase III ASTRO was marginal for what would have been an expensive program. There’s also the issue of Douglas vastly exceeding the question posed by the USAF—it’s unclear that there was any interest on the part of the Air Force in anything other than Phase I. This in turn defeated the purpose of building a fully operational craft for pilot training.

Sources

“Air Force Studies Space Trainer”, Missile and Rockets. September 3, 1962.

M-19 “Gurkolyot”: Grab the Problem by the Throat, Not the Tail

Myasishchev M-19 Gurkolyot schematic

A schematic of the M-19. Despite its great width and length, it was to be very flat, and mass only 500 tonnes. Image by the author, released to the public domain. Click for a larger view.

What it was: The Ministry of Aviation’s candidate for a Soviet shuttle, an apparent attempt to wrest control of the Soviet crewed space program away from the Ministry of General Machine Building. It was a runway-launched, single-stage-to-orbit spaceplane using a hydrogen propellant-based nuclear engine, designed by the Myasischev bureau that had previously worked on the VKA-23.

Details: After the first Myasishchev bureau was dissolved 1960 and many of its people moved to OKB-52, Vladimir Myasishchev didn’t lose his interest in spaceplanes. He became head of TsAGI, the Soviet experimental aviation bureau, then in 1967 was allowed to refound his own bureau, at which point he picked up from where he left off. A few years later the Soviet Shuttle project began, and Myasishchev was in the large camp of designers who were skeptical of the American design which slowly became the favorite behind the Iron Curtain.

Many years earlier, responsibility for the development of rockets in the USSR had been disavowed by the Ministry of Aviation and fallen instead to the Artillery wing of the Red Army. When ballistic missiles and rockets became the glamorous thing in the late 50s the aviation types came to regret their decision and repeatedly tried to barge into the business—Vladimir Chelomei came from the aerospace side of things, for example. Now that the USSR was in the large, reusable orbiter business, the Ministry of Aviation chose Myasishchev’s new bureau as their new champion and set him to work.

What the V. M. Myasishchev Experimental Design Bureau then proposed was a series of three craft, with several variations on each type, that would start with a high-speed test-bed and end with an orbital spaceplane. The middle craft was a reasonable knock-off of the NASA Shuttle, but the first and third were a radical alternative program. Back in the 1960s an engineer at NII-1 (“Institute of Jet Aviation-1”), Oleg Gurko, had come up with a novel concept for a SSTO, based around a nuclear reactor, the details of which we’ll explore shortly.

His suggestion got nowhere in the 60s despite his approaching both Myasishchev and Mikoyan, representing the Aviation Ministry for which he worked. Once work began on the Soviet shuttle, however, the Aviation Ministry’s interest picked up and the Myasishchev bureau was told to work on a proposal based on Gurko’s idea. Myasishchev himself realized that this SSTO would be a massive leap that would take a long time to develop, but he was uneasy with merely copying the American shuttle as that kind of a project would only be completed several years after the United States was flying (as indeed was the case, with STS-1 occurring in spring 1981 and Buran’s one, crewless flight being in November 1988). If his country was going to be behind anyway, why not work on a project that would at least offer the opportunity to leap ahead during the delay? He reportedly summed up his approach as “Grab the problem by the throat and not the tail, or else you will always have the tail”.

The breadth of Myasishchev’s ambition can be measured by understanding that the first plane in his program was not just a testing ground but, in order to bring the Ministry of Aviation on-side, was intended to double as an operational Mach 6 bomber flying at 30 kilometers up, twice as fast and fifty percent higher than the XB-70. The final plane was considerably more capable than even that.

Weighing in at 500 tonnes with fuel, the M-19 was a very flat, 69-meter long triangular wedge with two small sets of wings, one at the tail and one as canards near the nose. Launching horizontally from a runway, the M-19’s trip to orbit would begin with twin turbofan jet engines burning liquid hydrogen. After getting up to Mach 4, the plane would switch over to scramjet engines, also burning hydrogen. In both cases, though, the engines had Gurko’s idea behind them for a little extra kick.

The M-19 would have had a nuclear rocket engine that would take over in turn once the scramjet pushed the plane to Mach 16 and out of the appreciable atmosphere around 50 kilometers high. As the reactor was just sitting there during the turbojets’ and scramjets’ operation, Gurko reasoned, why not use it to superheat their exhaust to increase thrust? The potential increase in efficiency was considerable, and as the nuclear rocket (already more efficient than chemical rockets) would only be used for the final leg, the low inherent fuel use of the air-fed turbo- and scramjets gave the M-19 a tremendous payload fraction: the 500-tonne fully fueled plane was projected to lift 40 tonnes to LEO in its 15m × 4m cargo bay, which compares favorably to even staged rockets. Consider the Space Shuttle at 2040 tonnes and 28 tonnes of payload, or the Saturn V at 3038 tonnes and 118 tonnes of payload. To move whatever was stored in it, the bay was to be equipped with a manipulator unit, and an airlock from the crew compartment allowed EVA. Behind the bay was a large LH2 tank and, it should be made clear, no oxidizer tank. The rocket would run on raw hydrogen, while the two different types of jet would use the air as their source of oxygen.

After completing its mission in orbit, the M-19 would then fly back home, using the same propulsion systems in reverse order to come into a powered landing at an airstrip somewhere in the USSR, with an astonishing cross-range capability of 4500 kilometers. This completely plane-like return was of considerable interest to Soviet space planners for other reasons too, as it meant that the M-19 would reduce search and retrieval costs to nil as compared to capsules unless there was an emergency. Under those circumstances the cabin was to be entirely ejectable, serving as a survival capsule for the three to seven cosmonauts that might be on-board..

That the M-19 was perfectly capable of flying as an airplane in the lower atmosphere made it much more flexible too, as it could be moved to a different launch site relatively easily. And, as it didn’t drop stages on the way to orbit, it could be launched in any direction without worrying about what was downrange—a problem that’s particularly difficult for the USSR and Russia, and has led the latter to build its newest cosmodrome in the remote Amur region by the Pacific Ocean.

Even in space the M-19 was unprecedentedly flexible, able to make repeated orbital plane changes by diving into the upper atmosphere and maneuvering aerodynamically. Whether performing an inclination change or coming down to land, the M-19 was protected by reinforced carbon-carbon (like the Space Shuttle’s leading wing edges) and ceramic heat tiles.

The rocket for the M-19 was to be be built by the Kuznetsov design bureau, also the builders of the conventional engines for the N1, and would have been the first operational nuclear rocket in the USSR (and indeed the world).

Testing beforehand would involve several flying test beds to develop hydrogen-burning engines and scramjets, drop test articles, and the aforementioned hypersonic test vehicle/bomber. Though Gurko himself did not work for the organization assigned to build the M-19 he consulted on it, and the M-19 gained the nickname “Gurkolyot” (“Gurkoplane”). If given the immediate go ahead, the Myasishchev Bureau predicted that the final craft would be ready for flight in 1987 or ’88.

What happened to make it fail: First, Myasishchev’s bureau was absorbed again in 1976, this time into NPO Molniya, newly founded to make the Buran orbiter. The Soviet leadership had placed their bet on a close copy of the US’ Shuttle.

Second, even Myasishchev called the M-19 his “swan song”, and that his ambition was to set the USSR on the right course, not see it through. He was in his seventies even before preliminary work began on the spaceplane, and his death in 1978 took away the program’s biggest voice. While some testing of a jet engine running on liquid hydrogen took place in 1988 (in the modified Tu-155 jet), and the first Soviet scramjet was tested on top of an S-200 missile in 1991, by 1980 the M-19 had receded into the future as a possible successor to Buran, rather than a competitor.

Then the USSR came apart from 1989-91, and the future of the Soviet space program was forced into radically different channels.

What was necessary for it to succeed: This is an awfully tough one to assess, as the M-19 is by some distance the most technologically sophisticated spacecraft we’ve looked at. It was based around so many novel approaches (a nuclear rocket engine, a scramjet, preheating the jets’ air, SSTO, and so on) that it seems impossible even with current aerospace technology. Scramjets and SSTO in particular are two things which seem to endlessly recede into the future as we come to understand how difficult they are.

However, Myasishchev and his bureau acknowledged that it was a radical departure, that it would take a long time to develop, and that nevertheless they thought it could be done—and they were some of the best aerospace engineers in the USSR, if not the world. Who am I to say they were wrong?

Even so, it does seem like they were. The problem was not an engineering one (even if I’m skeptical that anything like this could fly before the mid-21st century), but rather an economic one. The M-19 needed time, and the USSR had surprisingly little left. How to fix the economic mistake on which that country was based? There are convincing arguments that it could not be fixed, and that at best the Soviet Union could have lasted only another decade or two past 1991 while becoming increasingly pauperized year-on-year—hardly the best environment for cutting-edge aerospace research. The M-19 simply could not fit into the time remaining, even with any reasonable stretch in the USSR’s lifespan.

Sources
Samoletoya EMZ in V. M. Myasishcheva, A.A. Bryk, K.G. Oudalov, A.V. Arkhipov, V.I. Pogodin and B.L. Puntus.

Energia-Buran: The Soviet Space Shuttle. Bart Hendricx and Bert Vis.

LKS: The Buran Alternative

LKS spaceplane on Proton rocket

An LKS orbiter atop its Proton launcher at the launch gantry. Original source and copyright status unknown, but pre-dating 2004. Note the folded wings: most sources do not mention this feature, with the implication that LKS’s wings were fixed, but the LKS is sufficiently badly documented that even this basic question is not definitively answered.

What it was: A small, 20-tonne spaceplane intended for launch on top of a Proton rocket. From 1979 to 1983, OKB-52 touted it as an alternative to the Energia/Buran shuttle.

Details: Continuing the parallel, military-oriented space program of OKB-52 (previous entries so far being the LK-700, Almaz, and the TKS), we come to the LKS. In late 1973 the Soviet government decided to respond to the prior year’s announcement by the United States that they would be building the Space Shuttle. OKB-1 was given the task of examining a large spaceplane in the same class as the Americans’, while Mikoyan and OKB-52 were ordered to look at something in the 20-tonne range.

The convulsions of 1974-75 pointed NPO Energiya, the former OKB-1, in the direction of responding to the American Space Shuttle with a quite-close copy (though not before sketching out the MTKVP), and eventually the “Buran Decision” was made in its favour in 1976.

Governmental decision or not, the ever-contrary Vladimir Chelomei and OKB-52 carried on with their own spaceplane from 1976-79 to address what they saw as Buran’s deficiencies: it was smaller, lighter, would be quicker and cheaper to develop and, in their opinion, be almost as capable. They called their two-cosmonaut craft the LKS (“Legkiy Kosmicheskiy Samolet”), meaning “Light Space Plane”.

Inevitably the LKS was to be put on top of OKB-52’s workhorse, a Proton rocket—though not man-rated, the intention was to do so for also launching the TKS anyway. This dictated much about the orbiter, starting with its mass. The Proton-K used until recently could lift just shy of 20 tonnes to low-Earth orbit, which is a bit less than a quarter of either a Shuttle or Buran orbiter carrying a full payload. So while the LKS had a similar shape to its larger cousins by design, its launch mass was only 19,950 kilograms, with a length of 18.75 meters and payload of 4 tonnes (compare with 37.24 meters and 27.5 tonnes for an American shuttle). This is, not at all coincidentally, close in mass to the TKS, and the two can be thought of flip-sides to one another as OKB-52 tried to be everything to everyone while also integrating their proposals into the larger space effort envisioned by Chelomei.

The LKS orbiter diverged from the larger shuttles in a number of other notable ways too, even after being redesigned to be essentially a half-scale version of the US Shuttle Orbiter (earlier incarnations had twin tail fins and wings with a straight leading edge). Its in-orbit engines were to burn N2O4 and UDMH, like every other motor of note proposed for use by OKB-52. Its landing gear was peculiar too, with a steerable wheel up front and landing skids under the wings. Chelomei also proposed to use a renewable ablative re-entry shield rather than the ceramic tiles common to the American and Buran orbiters. As aerodynamically similar as it was, though, it still had the same ~2000 kilometer cross-range capability and would glide in to land at a similar speed (reportedly 300 km/h, a bit slower than the Shuttle’s 350).

OKB-52 had made a full-sized mockup of the orbiter by 1981, then Chelomei pounced during the period of Soviet alarm following Ronald Reagan’s “Star Wars” speech in March 1983. In a letter written directly to Leonid Brezhnev he suggested that the LKS could be used to quickly and cheaply deploy counter-missile lasers into orbit. Sources differ on whether this was as satellites in the payload bay, or if he meant a fleet of unmanned LKSes carrying the lasers directly—but most lean towards the latter.

What happened to make it fail: Having raised the profile of the LKS as a counter to SDI, Chelomei’s efforts came under the scrutiny of the Soviet military. A state commission was convened in September of 1983, headed by the deputy minister of defense Vitali Shabanov. It eventually came to the conclusion that the LKS would not be useful for missile defense; Chelomei was reprimanded for working on an unauthorized project. Previous setbacks on his projects never had much effect on the headstrong designer, but the LKS came to a definitive end when Chelomei died in August 1984. The mock-up was apparently destroyed in 1991.

What was necessary for it to succeed: OKB-52 were right that Buran would take too long and cost too much. Originally planned to fly in 1983, the Soviet shuttle made its sole, automated flight in November 1988; even then it was not completely fitted out and was only suitable for a 206-minute flight (and the next was not scheduled until 1993!) Something like 20 billion rubles, at a time when the ruble was officially marked at better than par to the US dollar, were spent on the program.

Even at the time there was resistance to the big orbiter, but NPO Energiya and Valentin Glushko‘s grip on the Soviet manned space program was firm. First you probably have to get it loosened somehow, though not so much that Chelomei and OKB-52 took over for them—as was discussed in the previous post to this blog, that would have left the USSR flying TKS spacecraft and not LKSes.

The difficult thing here is that if a small spaceplane got built there are two other, likelier candidates. Prior to about 1990 it probably would have been the other 20-tonne study mentioned at the beginning of this discussion, Mikoyan’s. The Spiral project got even further along than LKS did, to the point of a subsonic demonstrator and orbital re-entry tests of scale models. After 1990, NPO Molniya, builder of the Buran shuttle, floated the MAKS shuttle, which introduced the wrinkle of being air-launched by the An-225 superheavy cargo plane originally designed to cart Buran around.

As a result, unless one can cook up a Soviet leader circa 1983 who had the desire to save money of Mikhail Gorbachev while also having the willingness to rise to the challenge of the Strategic Defense Initiative, the LKS probably does not fly.

Sources

Light Space Plane, LKS“, Anatoly Zak.

‘LKS’, The Chelomei Alternative to Buran“, Giuseppe di Chiara.

Malysh v teni «Burana»: Sovetskiy legkiy kosmoplan“, Oleg Makarov. Popular Mechanics (Russian Edition) #93. July 2010.

“The Soviet BOR-4 Spaceplanes and Their Legacy”, Bart Hendricx, The Journal of the British Interplanetary Society, vol. 60. 2007.

Energia-Buran: The Soviet Space Shuttle, Bart Hendricx and Bert Vis.

Sidebar: Alexeyev/Sukhoi Albatros

albatros

A conjectural diagram of the Albatros launcher, by Mark Wade of Encyclopedia Astronautica. Click for a link to the associated article. Used with permission.

Rostislav Alexeyev built the latter part of his engineering career on ground effect, which is the demonstrable fact that a wing generates more lift and experiences less drag when it’s in close proximity to the ground than it does while high in the air. In general aircraft don’t take advantage of it when cruising because of the increased risk—the ground is right therein the event of something going wrong, but Alexeyev was an expert on hydrofoil design and felt that the problem was sufficiently mitigated by flying over water to be worth attacking. Between the Khrushchev era and his death in 1980 he built his largest ekranoplan (“screen plane”), the so-called “Kaspian Monster” (KM: korabl maket, “test vehicle”) which met a watery fate in an accident not long after Alexeyev’s demise.

If you’re the sort of person who’s interested in Soviet crewed spaceflight you’re probably the sort of person who finds Russian ekranoplans and hydrofoils interesting too, but you may be wondering where the connection is between the two that would cause the latter to show up on a  blog devoted to the former. The intersection of this particular Venn diagram is the Albatros, outlined in a remarkable letter to the British Interplanetary Society’s Spaceflight magazine, published in 1983.

Long-time readers will recall that the Soviet space program was in disarray for much of the early 1970s, with 1974 being the year of crisis. Vasili Mishin was replaced by Valentin Glushko as the man in charge, and officials higher than him forced a change in focus from Moon missions to a space shuttle and space stations. For a period of time everything was in the air, and as was endemic to the Soviet space effort various other empire builders tried to get themselves a piece of the pie.

The design bureau of OKB-51 lurked on the edges of the Russian space program right from the very beginning, but never managed to convert its expertise in high-performance aircraft into any concrete projects. In 1974 they teamed with Alexeyev’s Central Hydrofoil Design Bureau to make a claim on the shuttle project, as at the time it was not yet settled that the Soviets would emulate the American Space Shuttle closely to produce Energia/Buran (consider, for example, Glushko’s MTKVP, which also dates to the same time). Their proposal was named Albatros, and it’s, so long as the source, space historian and writer Neville Kidger, got his Cold War information right, the only triphibious spaceplane ever proposed, requiring both water and air to get into orbit and land for its return.

One can see what, perhaps, they were thinking: margins are punishing on space vehicles, and it takes only a little inefficiency to turn a potentially useful craft into something that lifts a uselessly small amount of mass to orbit. Using aircraft as airborne launchers has been mooted a few times, why not use a ground effect “aircraft” to squeeze a little more oomph into your package?

The result was a three-stage vehicle, the first of which would have been a roughly 1800-ton, 70-meter long, Alexeyev-built, hydrofoilnot a full-fledged ekranoplan, alasthat could be thought of as a maritime version of the Space Shuttle’s external fuel tank. It would carry 200 tons of LOX and LH2 to feed the initial boost of the second stage’s motors.

Mounted on top of the hydrofoil, the estimated 210-ton second stage would use the first’s fuel to get up the whole arrangement up to 180 km/h over the course of 110 seconds, using the Caspian Sea (or the Aral or Lake Baikal) as a runway. Then it would disconnect and launch itself off the now-empty barge to consume its own propellants. This stage would be a high-speed reusable winged rocket plane/booster from Sukhoi that would lift the third stage—the actual spaceplane, also from Sukhoi—to a high altitude. There the latter would kick itself into orbit while the booster coasted into landing, possibly under pilot control; sources don’t say if the booster was to be manned, but with Sukhoi’s background it likely was.

The final stage was a tail-less rocket plane, about 80 tons in mass and 40 meters in length, so comparable to the American orbiter. It was estimated to have 30 tons of payload to LEO and a crew of two. It would have been larger than but was otherwise similar in appearance to some iterations of the Hermes shuttle, or to a lesser extent the later Russian/European Kliper. It was the most run-of-the-mill part of the whole vehicle, its design actually being closer to the American shuttle than the MTKVP. The air-based launcher was a radical approach, if not unique, but the underlying hydrofoil was the truly surprising suggestion.

It’s not difficult to see why the idea never went anywhere. Even putting aside the two partners’ inexperience with designing spacecraft, their proposed setup is ludicrous on its face, with tons of volatile propellant skimming over the water at triple-digit speeds, regardless of what its engineers might have actually calculated and put to paper. The likes of Dmitri Ustinov would have blanched if asked to sign off on it, as the country’s internal politics made Soviet decision makers inherently conservative. If they were eventually driven to insist on a close analog to the Shuttle over other proposals, one can only imagine what they thought about this one.

Sources:

“Albatros”, Mark Wade, http://www.astronautix.com/a/albatros.html.

Chief Designers 6: Max Faget

"Cutaway Diagram of Project Mercury"

A cutaway drawing of Max Faget’s biggest achievement, the Mercury capsule.This 1959 diagram was drawn in an unsettled period between the “C” and “D” designs of the craft, the latter of which flew. Public domain image from NASA.

Maxime Allen Faget was the premiere American spacecraft designer from the days of the Mercury capsule to the initial stages of the Space Shuttle. It was due to his understanding of Harvey Allen’s “Blunt Body Theory” that American spacecraft had their iconic bell shape, and his strong opinion about his ideas for Mercury, Gemini, and Apollo led contractors to coin the aphorism “What Max Faget wants, Max Faget gets”. Experience proved that going against his intuitions was the quickest route to a losing bid in NASA design competitions.

Faget was born in Stann Creek, British Honduras (now Dangriga, Belize) on August 26, 1921. His father was a noted tropical disease researcher, employed by the British, and his family was of French descent via Hispaniola and New Orleans (his last name was pronounced in the French manner, fa-Zhay). His father was also American and so so was young Max; accordingly the family eventually returned to the United States. The younger Faget reportedly had a passion for science fiction—he had a subscription to Astounding Science Fiction—and model airplanes, interests which presumably led him to his ultimate career.

Max Faget and Frank Borman

Max Faget, foreground, and astronaut Frank Borman. This photograph was taken in April 1967 during the investigation into the Apollo 1 fire. Public domain image via NASA.

In 1943 he graduated from Louisiana State University (where his roommate was rocket designer Guy Thibodeaux) with a degree in mechanical engineering, then served on the submarine USS Guavina during World War II. After the war ended he joined NACA in 1946, which meant he was in on the ground floor when that agency became NASA in 1958.

Even before that happened he had been working on the design of a space capsule radically different from what had been considered before. Experiments in the mid-1950s with ballistic missiles had proven that the best simple way to get something safely out of orbit was with a blunt-ended capsule rather than the sharply pointed craft that had been imagined necessary until then, or the lenticular shape that was also considered at the time. Taking this idea, Faget came up with a rough sketch that would eventually evolve into the Mercury capsule.

This work was mostly done after Faget joined the Space Task Group, a group of 45 people—37 of them engineers—based out of Langley Research Center in Virginia until 1961. With the addition of Canadian Avro engineers, Faget gained his right-hand man for Mercury, Jim Chamberlin. Then in 1961, following Kennedy’s declaration that the United States was going to send a man to the Moon, the Space Task Group was greatly enlarged and moved to become the Manned Space Center (now the Johnson Space Center) in Houston, Texas. Their task was to follow through on Kennedy’s promise, and Faget was its Chief Engineer from February 1962.

As a result, Mercury went ahead with him in the lead; among other things, he created the escape tower for Mercury and later adapted for use with Apollo. He would then go on to shepherd the Gemini and Apollo spacecraft designs to completion.

Faget had an informal veto on NASA’s spacecraft designs from about 1958 to 1970, and he was not afraid to use it. Most notably the design competition for the Apollo spacecraft was jury-rigged to select the second-best scoring proposal over that of Martin-Marietta because it more closely resembled what he had designed himself in counterpoint to the external proposals.

Space Shuttle concepts

Space shuttle concepts around 1970. Faget’s “DC-3” is second from the top on the right. The bizarre SERV is top left. Public domain image from NASA.

His touch left him only once during his career at NASA, during the Space Shuttle design. At first he favoured something like Big G, but he soon came over to the side of a reusable spaceplane. While each NASA spaceflight centre had its own ideas, Faget considered all of them too complex and came up with a simpler, stubby-winged design called the “DC-3” in honour of the great cargo plane of the early days of aviation. This set off a battle within NASA over the cross-range capability of the Shuttle-to-be, with one side eventually settling on a delta-winged configuration and one side taking up Max Faget’s design as adopted and submitted by North American Aviation. Only the delta-wing arrangement would give the Shuttle a high cross-range, and that was felt to be useful enough that many in NASA held out against Faget’s proposal until the scales were tilted in their favour. Faced with a budget crunch, new NASA director James Fletcher arranged to have the US Air Force brought on as a partner for the spaceplane, and their requirement for cross-range was even higher than that envisioned by the delta-wing partisans at NASA. The DC-3 was abandoned and the Space Shuttle as we now know it began to take shape. His failure to get his design selected was apparently a source of minor annoyance to Faget for the rest of his life, but he dove into the construction of the new spaceplane and helped bring it to completion.

Faget left NASA in late 1981, not long after the flight of STS-2. He founded Space Industries Incorporated in 1983, which focused on projects intended to explore the unique conditions of space as they could be applied to industry and chemistry. Their Industrial Space Facility—a small, unmanned space station—never flew, but the Wake Shield Facility (which used its motion through space to make a “shadow” of ultra-high vacuum behind it it) ran experiments on three Space Shuttle missions from 1994-96.
Faget died of bladder cancer on October 10, 2004 at the age of 83.

Tianjiao 1/Changcheng 1/V-2/H-2: The Chinese Spaceplane

changcheng-1-spaceplane

An artist’s rendering of Changcheng 1, the likeliest of four spaceplane options considered by China in 1989. Image source and copyright status unknown, please contact the author if you know either. Click for larger view.

What it was: A set of studies in 1988 that looked to commit China to a spaceplane by no later than 2015. Four different approaches were examined:  am engine-less small spaceplane lifted by expendable boosters that would need to be designed, a craft similar to a scaled-down Space Shuttle lifted by then-current boosters and it’s own new engine, a Shuttle-sized orbiter of original design launched vertically on a flyback booster, and finally an advanced re-usable horizontal takeoff plane in which the first stage would be air-breathing and the second a spaceplane which would launch off the first’s while in mid-air.

Details: Following the cancellation of Project 714 the manned Chinese space program lay fallow for at least ten years. There are some signs that there was an attempt to revive it in the late 1970s, but the evidence for this is circumstantial: China successfully launched and recovered its unmanned FSW reconnaissance satellites, which were large enough to serve as a basis for a one-man space capsule, and there was a public reveal of an astronaut cadre in January 1980. There are rumours that the sudden cancellation of that training program in December of the same year was due to the loss of a taikonaut on a suborbital flight, but they’re probably just that: rumours. It’s much likelier that the program ended due to economic weakness and the political uncertainty between Mao’s death in 1976 and Deng Xiaoping’s consolidation of power in 1981.

By 1986 the issue had come to the fore again. As part of a general drive toward economic progress China had established Project 863 (863计划), a government program to develop advanced technical skills, similar to its contemporary MITI in Japan. Project 863 recommended seven scientific/engineering projects of which two were space related: 863-204, for the development of a manned space program, and 863-205, which looked to build a space station. The latter rose and fell with the space transport system and so didn’t get very far, but over the next few years several simultaneous studies were made in aid of 863-204. By 1988 the panel of experts assigned to evaluate the studies and synthesize them into a way forward had decided that the correct approach would be to aim for a manned ballistic capsule by 2000, with a spaceplane to follow by 2005-2015 depending on which of four approaches was taken—there was also a fifth, leasing Hermes shuttle technology from France, but that possibility was cut off by European sanctions following the Tiananmen Square Massacre.

tianjiao-1-spaceplane

Tianjiao 1. Image ©Mark Wade of astronautix.com, used with permission.

The simplest of the four approaches suggested was Tianjiao 1 (“First in Space 1”), jointly proposed by the Shanghai Academy of Spaceflight Technology (SAST—the later developer of the Shenzhou capsule) and the aircraft division of the Ministry of Aerospace Industry. This was virtually an exact copy of the American shuttle or Buran’s aerodynamic shape, with only upturned wingtips, but a copy that was greatly scaled down: about half-size in length and width and a quarter of the mass. It could be launched into orbit on top of three expendable boosters—two smaller (and probably using N202 and UDMH) on the sides of a larger LOX/Kerosene rocket. The orbiter itself would have had no engines.

It’s reported that Tianjiao 1 would have had a crew of three, which is surprisingly large for its size, and had a payload of two or perhaps three tonnes to LEO. Had it gone forward, it was to have been launched for the first time in 2005.

Next in complexity was Changcheng 1 (“Great Wall 1”), which was suggested by the China Academy of Launch Vehicle Technology (CALT), at the time part of the Ministry of Aerospace Industry. It too closely resembled the US Space Shuttle, with just a few modifications. It would have no tail fin and two small wing-tip stabilizers, while a jet engine would have been added at the tail end for low-speed flight. To get to orbit it would have been lifted by three expendable boosters based on Long March technology and burning N2O2 and UDMH. The shuttle itself would be perched in the centremost of the three boosters and complete the burn to orbit after separation from the first stage rockets using its own engine running on the same two propellants.

The Changcheng 1 orbiter would have been about two-thirds the size of the US Shuttle or Buran, being 24.7 meters long, having a wingspan of 14 meters, and a landing mass of 32 tonnes . It would have carried five taikonauts (two of them pilots) and had a payload of 5 tonnes to LEO. If all went according to plan, the first flight would have been in 2008.

v-2-spaceplane

The unfortunately-named V-2 spaceplane. Image ©Mark Wade of astronautix.com. Image used with permission.

The next proposal was for a spaceplane similar in concept to the US Space Shuttle but a little more advanced. Dubbed V-2, it was suggested by a third division of the Ministry of Aerospace Industry. Like Changcheng 1 this was a two-stage vertical takeoff system, the difference with the first stage being that it was recoverable like that of the US Shuttle and Buran. The proposal took the concept further, however, making the entire first stage recoverable (the STS lost its main fuel tank, while Buran expended its central Energia rocket) through a strategy that’s been considered several times but never developed: it would have been a flyback booster. Essentially the idea was to develop two shuttle-like bodies, the second of which would be the actual orbiter and which would side-mount on the first “shuttle”—this one being responsible for the original launch on a plume of burning O2 and kerosene. At separation partway into space, the orbiter would continue on upwards, propelled by its own LH2/LOX engines, while the booster shuttle would separate and fly back unmanned to a landing strip. There it would touchdown, roll to a stop, and be refurbished.

The V-2 orbiter would have been about the same size as the US Shuttle, and would have mounted a twenty meter long, three-meter in diameter pod on its back. Unfortunately it’s not known if the pod was intended for cargo and the main portion of the orbiter was for crew, or if the pod was for both crew and payload. As a result we’ve no good idea how many taikonauts it would have carried and how much it would have got to orbit. Whatever it would have done, though, it would have done it sometime around 2015.

H-2-spaceplane

The horizontally launched H-2 spaceplane. Image ©Mark Wade of astronautix.com. Image used with permission.

The final possibility was the most advanced of all, a completely reusable two-stage-to-orbit spaceplane proposed by yet another division of the Ministry of Aerospace Industry. This one would take off horizontally at a paved strip by having its first stage fire eight LOX/LH2/CH4 tripropellant engines. At about Mach 2 the first stage would have fired up an air-breathing scramjet powered by liquid hydrogen and between that and its rockets would get to hypersonic speeds. The orbiter would then separate from its position on the first stage’s back and would have climbed to orbit on four LH2/LOX engines. Both the first stage and the orbiter would have been able to fly back to base and land on a landing strip for re-use.

This H-2, as it was called, would have been a monster. The first stage would have been 85 meters long, would have had a wingspan of 36 meters, and would have massed 79 tonnes when landing—lighter than but otherwise bigger than an Tupolev Tu-160, the largest supersonic plane ever built. The orbiter was slightly larger than the American and Soviet shuttles, at 40 meters by 12 meters by landing mass of 25.3 tonnes, though it had a lower maximum orbital height of 500 kilometers. Furthermore all that effort would have led to a fairly small payload: only six tonnes, as compared to 24 tonnes for STS and 30 tonnes for Buran. Its crew would have been two or three. Like the V-2 it was supposed to have flown sometime in 2015, though this seems optimistic. Had they pulled it off by then, or even somewhat after, it would have catapulted China to the forefront of reusable space technology.

After considering the possibilities, the final report of the 863-204 committee chose a ballistic capsule for the initial manned space program, to be followed by Changcheng 1.

What happened to make it fail: Deng Xiaoping was unpersuaded by the arguments made in favour of a spaceplane, or even a capsule, and refused to let either go forward. Ultimately he was pragmatically interested in economic development only, and saw the long-term nature of both programs (ten years to the ballistic capsule and up to twenty-five to the plane) as being too long a time frame to be useful in that regard.

What was necessary for it to succeed: Timing is everything. Deng began loosening his hold on power in 1989 when he resigned as Chairman of the Central Military Committee, thus giving up control of the Chinese military. In one of the first signs of their independence, the People’s Liberation Army Air Force decided to support the proposed manned ballistic capsule, possibly as part of their general modernization push in the early 90s. By 1991 the Ministry of Aerospace Industry formally re-established a Chinese manned space program and in 1992 got approval for a space capsule Premier Li Peng—the number two man in the government post-Deng, after Jiang Zhemin. This rapidly evolved into Project 921, which is to say the successful Shenzhou spacecraft that China has been launching with taikonauts aboard since 2003. Note the timing there: in 1989 Project 863 was aiming for a manned capsule launch in 2000, while three years later Project 921 was founded and got its launch three years after its predecessor predicted. Project 921 can be fairly interpreted as just being a new name for the first part of its immediate ancestor.

So with just a slightly different order of events it’s not too difficult to see the spaceplane going ahead. If 863-204’s final report had been made a year or two later than it was, Deng would have been in the lull of his informal control that followed his resignation (he managed to re-assert his soft power in 1993). Li Peng was a fan of state control and planning—he was also the godfather of the Three Gorges Dam—so he seems like just the type to think that working towards a 25-years-distant spaceplane would be the way to go. What would actually got built on that decompressed timeline is an open question.

The other route to Changcheng 1—Deng resigning a few years earlier—depends on how much you think Premier Li was instrumental to getting the Chinese manned space program running. If you think another figure in the Communist Party would have stepped into his shoes on this then it’s also a plausible route to a world where a Chinese spaceplane would be flying now or in the next couple of years. On the other hand, if you think he himself was necessary it’s likely that this wouldn’t have worked: Li ended up in the high position that he did because of his role in suppressing the Tiananmen Square protests in 1989. Furthermore his political longevity can be partially attributed to the CPC wishing to assert their own correctness in the face of world opinion condemning their actions. Without June 4, 1989, Li likely would not have been in the position he was, or remain in it as late as 1998 when his power waned.

And while it did not go ahead as planned in 1989, the Chinese dream of a spaceplane is not entirely dead. While Western observers have had a hard time figuring out what to make of it, in 2007 the Chinese media publicized a few images of what appears to be an air-launched, sub-scale, and sub-orbital spaceplane prototype, similar in appearance to the US Air Force’s X-37B.

MTKVP: Glushko’s Opening Gambit

mtkvp

Schematic views of the MTKVP as first originally proposed (above) and as redesigned (below) in the first attempt to satisfy the Soviet military’s desire for a Space Shuttle analog. Image ©Mark Wade of astronautix.com, used with permission. For much more detailed (but unfortunately not free) images, visit buran.ru.

What it was: A fairly sophisticated 1973-76 attempt to square the circle between the ballistic capsules favoured by Russian spacecraft designers and the Space Shuttle analog being demanded of them by the Soviet military. It would have been an elongated lifting body with a rounded triangular cross-section and small folding tail stabilizers. As designed it would have had a payload to LEO of roughly fifteen percent more than the US Space Shuttle.

Surprisingly little information about this craft is available for something that was at the forefront of Soviet space development for nearly two years, and what there is is contradictory: the author even found four different names for it (MTKVP, MTKVA, MTC-VP, and MTK-AM) let alone a raft of inconsistencies in the project’s details. Much more than other False Steps posts this is an attempt to synthesize what’s available and may not be completely accurate. One presumes that only further discoveries in Soviet archives are going to bring this one into proper focus.

Details: As discussed previously, the Soviet space program went through a radical reorientation between 1974 and 1976, as Vasili Mishin was removed as its head, the N1 rocket was cancelled, and the N1-L3 lunar landing mission was scrapped. While the new head Valentin Glushko was well aware that he was expected to focus on a reusable space plane and space stations in low Earth orbit, for eighteen months he entertained the possibility that he could satisfy the military and military-friendly backers who had allowed him to take over while still retaining the dream of a Russian Moon base (or, to be more precise, Glushko’s vision for how this would be done, Zvezda).

The key difference he wanted was a big rocket booster that he could also use for Moon projects. Accordingly, what he supported was an effort to develop a reusable transporter without engines. This could be put on top of the booster, unlike the US orbiter, which needed clearance for its engines and had to be laterally mounted on the side of its rocket-and-fuel-tank stack. While initially conceived as a cylindrical body for cargo with a separable ballistic capsule on top for the crew return, it soon evolved into the MTKVP (“Reusable Vertical Landing Transport Craft” in Russian).

In this new version of the craft the cylinder was replaced with a triangular prism with rounded edges. It tapered gently toward one end, where the crew cabin—now permanently attached to the vehicle—was located, while a single orbital maneuvering engine and small thrusters were placed at the other wider end. The aft end also sported two small winglets, which were folded up during launch and in orbit, but descended to give the MTKVP (in combination with its body shape, which was aerodynamic at hypersonic speeds) a bit of controllability. All told it had about 300 kilometers of cross-range capability, which in usefulness was its major negative compared to the American Space Shuttle.

The booster which it would have topped was a variation on the largest rocket in Glushko’s proposed RLA series, the RLA-150 Vulkan. Dubbed the RLA-130V, it was a recognizable ancestor of the Energia rocket. The Vulkan’s upper stage was removed and replaced with the orbiter. That sat on top of a a large liquid-fuelled core (LOX and LH2) in the centre and six liquid-fuelled boosters around it; these burned LOX and syntin, an artificial hydrocarbon fuel developed by the Russians with better performance than kerosene. In contrast to the Shuttle, which lost its external fuel tank but had recoverable boosters, the launch vehicle would have been completely expendable.

The main body of the MTKVP was dominated by an aft cargo bay, which like the American orbiter was protected by two long bay doors which could be opened to space. As it didn’t have to lift engines and full-fledged wings to orbit, it was to be capable of carrying some 30 tonnes of cargo to orbit, and bring back 20: more than the Space Shuttle, despite the disadvantage of being launched from higher-latitude Baikonur instead of Cape Canaveral.

The MTKVP would have been about thirty meters long; some sources say 37 but this likely includes the mating adapter to its booster. In all it weighed 88 tonnes, which if you add on the 30 tonnes of cargo means the RLA-130V would have been lifting 118 tons to orbit—and if you noticed that that is similar in lift to the Saturn V and N1, congratulate yourself for finding the hidden Moon rocket.

mtkvp-landing

Image of the MTKVP coming in for landing, vertically. Image source and copyright status unknown, please contact the author if you know. Click for a larger view.

Once it dropped below subsonic speeds, to Mach 0.75 at a height of 12 kilometers, it would demonstrate its other major difference from the Shuttle. The V in its name stood for “vertical” (in Russian, anyway) and instead of coming in roughly horizontally to a landing strip, it would deploy parachutes and descend vertically. At the last moment it would fire retrorockets on its underside and settle to ground on skid landing gear. So unlike the US’ orbiter it didn’t need a landing strip, and in fact didn’t need a prepared landing site at all. As long as the ground was flat—a common condition in much of the former Soviet Union—it could land pretty much anywhere.

The first flight of the MTKVP was proposed for 1980.

What happened to make it fail: The Soviet leadership—even Dmitri Ustinov, who had been one of his main supporters in his push to take over TsKBEM and transform it into NPO Energiya— made it abundantly clear to Glushko that they were not going to give him his Moon base, and that furthermore that they would not accept anything less than a close copy of the Space Shuttle.

The psychology of the second part of this decision is interesting. Interviews with the various players since the fall of the Soviet Union have established that in the years following the Moon race the Russians had a bit of an inferiority complex toward American space technology. Though their spacecraft designers could see no advantages to the Space Shuttle as compared to expendable systems like Soyuz and Proton, there ensued a battle between those who felt that their analysis should be read at face value and those who were sure that they were missing something.

While the first of these approaches held the field for a while, the political and military people calling the shots became progressively more paranoid about what the Shuttle would be able to do and that the USSR was simply failing to see. Dmitri Ustinov in particular changed his tune after hearing from a shuttle enthusiast at NPO Energiya and from KGB Chief Yuri Andropov—one of the key believers in a hidden military purpose for the US’ orbiter.

For their part, the spacecraft designers had realized there were a number of problems with MTKVP that they were not sure they could solve. Many of them could have been cracked: for example, it would have had to withstand 1900 Celsius on re-entry rather than the maximum 1500 of the Shuttle, but the tiles they later developed for Buran were within striking distance of this. Nevertheless two issues seem problematic even today.

First, as it was designed to land virtually anywhere flat, there was always going to be the problem of how to get the MTKVP back to Baikonur for the next launch. Its low cross-range capability meant that it couldn’t always make it to an airstrip where railways or roads could be used to transport it, let alone something like the enormous Antonov An-225 used to carry Buran: it was by many measures the largest aircraft ever built and needed long, special-purpose runways.

Furthermore the lack of cross-range capability made it hard to get the MTKVP back to Soviet territory in case of an emergency. The Space Shuttle could, if absolutely necessary, land in places as widely scattered as Gander in Newfoundland, Banjul in Gambia, and Guam. Russian insistence on secrecy ruled out this sort of emergency landing. Paradoxically, the USSR was both too big and too small—there wasn’t the necessary infrastructure in many places up-country where the MTKVP might land, and it was unable to be underneath every possible place where a crippled mission might want to land.

Accordingly even as the MTKVP was being designed there was a portion of NPO Energiya working on something much closer to the Shuttle, the OS-120—which even had on-board rocket engines, meaning it was an even more slavish copy of the US orbiter than Buran turned out to be. It seems to have begun as a “due diligence” project, with Glushko far more interested in MTKVP because that approach would allow him his big booster. As pressure from the Shuttle advocates in the military increased, however, Igor Sadovksy (one of Korolev’s long-time engineers going back to the 1950s, and the man in charge of the OS-120) synthesized the two approaches by moving the engines off the orbiter and onto the rocket stack: in other words, the Energia superheavy launcher and the Buran shuttle.

This gave Glushko his big booster and a way to satisfy the military and political forces pushing for a winged shuttle. On January 6, 1976 he approved the proposal, and work on MTKVP and the RLA-130V stalled and eventually stopped; in the future he would refer to this day as “Bloody Sunday”, as he realized it also meant the death of his Moon base plans for the foreseeable future. Buran’s huge costs would see to that. Glushko’s Zvezda base was allowed to move forward in a desultory fashion until 1978, but were cancelled outright then when Buran fell behind schedule and NPO Energiya was forced to work on it almost exclusively.

What was necessary for it to succeed: There are actually a few different avenues that could have led to the MTKVP flying.

A somewhat less-successful US Space program would have helped assuage the Soviet inferiority complex at the time and given them the confidence to go ahead with something more different from the American shuttle, rather than quite literally building an orbiter in which they did not see (but merely suspected) an advantage.

The other way to keep it a going concern is to note one of the reasons Glushko submitted to “Bloody Sunday”. A movement was afoot by engineers who had worked on the N1 to propose the revival of that rocket to the Soviet leadership, and they were preparing to make their pitch in February of 1976. The MTKVP was relatively agnostic about the rocket on which it could be perched: there’d be no real difficulty in designing it to sit on top of an N1. Glushko’s pride couldn’t allow the resurrection of his rival Korolev’s dream booster after having advocated against it for more than a decade, so in part he chose to scrap the top-mounted orbiter in favour of a laterally-mounted Shuttle analog because there was no way to attach one to an N1.

Give Vasili Mishin a successful flight of an N1 (perhaps due to a little more luck with the last failure in November 1972) and Mishin probably could have headed off the coup of 1974. The switch away from a Moon base and toward a Shuttle-of-sorts would have probably happened anyway, and the same engineers who developed MTKVP under Glushko would have been in place in this scenario. All other things being equal, they’d have ended up with a similar design, and would have had a boss who wasn’t beholden to the military people who wanted Buran. Under those circumstances we could have seen an MTKVP (or something quite like it) flying on Korolev’s superheavy instead of Glushko’s mooted replacement.

Energia: The Last Big Rocket

energiya-buran-launch

A rendering of the Energia rocket launching its primary payload, Buran. Unlike the American shuttle stack, the rocket could be launched on its own, and was in the same class as the Saturn V. Image source and copyright status unknown. Please contact the author if you know of its origins. Click for a larger view.

What it was: A Soviet super-heavy lift launcher. It was one of the three most powerful rockets ever built, in the same class as the Saturn V as well as the ill-fated N1 it was partially intended to replace. Its other main role was to act as a booster for the Soviet space shuttle, unlike the American one which got itself to space using its own engines fed by its large external fuel tank. Though it did go to space twice in 1987-88 it qualifies for this blog because it didn’t fly any more after that, despite being intended as the heavy-lift backbone of the Soviet Union for well into the 21st century.

Details: For about twenty months after taking over TsKBEM (the former OKB-1) from the disgraced Vasili Mishin, Valentin Glushko worked toward a lunar base centred on a derivative of the Proton rocket, a design of Vladimir Chelomei’s using hypergolic engines designed by Glushko.

By early 1976, however, Glushko had been told by Soviet leadership to stop work leading to the Moon and instead focus on a Soviet space shuttle in response to what they perceived as the military threat posed by the US’ own Space Shuttle. While the eventual Buran shuttle would bear a strong resemblance to the American orbiters, Glushko made one major change that let him keep his Moon base alive surreptitiously.

In the American Space Shuttle, two strap-on boosters helped pushed the shuttle stack to 46 kilometers high. But some of the thrust up to that level, and all of it from the moment of booster separation, came from engines on the aft end of the Shuttle. In other words, the Shuttle was at least partly its own launch vehicle, while the external tank to which it was attached was not in any way a rocket. It existed solely to carry fuel for the Space Shuttle’s main engines.

Glushko chose instead to build Buran with no engines at all. It was solely a glider for returning to Earth, while it was lifted into orbit by engines on the end of what superficially appeared to be a copy of the US Shuttle’s external fuel tank—but was actually the Energia rocket. In other words, the Soviet Union’s chief designer hid a Saturn V-class booster, potentially useful for his beloved Moon base, in his space shuttle system.

Energia began when Glushko took over TsKBM (in fact the name “Energia” was applied to the newly reorganized department as NPO Energiya long before it was given to the rocket) and brought with him his new RLA (“Rocket Flight Apparatus” in Russian) rocket designs. In the early 1970s the Soviet Union had no less than three active launchers, discounting the N1—R-7 derivatives, the Tsyklon, and the Proton. All three were different from one another in design and construction, and the cost of running them were accordingly high. For the third generation of Soviet launch vehicles the requirement was to build light, medium, heavy, and super-heavy launchers from one common set of components, and the RLA was Glushko’s proposal to meet this. Of the various designs, the super-heavy RLA-135 is the one that interests us.

The RLA series was passed over in favour of the Zenit rockets of the Yangel Design Bureau but Yangel didn’t have a super-heavy solution, stopping instead at the “medium” level and leaving an opening for Energia. Glushko took his RLA-135 design, which had a large core rocket and strap-on boosters, and proposed it again with a modular version of the Zenit as the boosters and the core being a new rocket designed by his bureau. His suggestion was accepted and the Energia was born.

Glushko did have to take one other hit to his ego, though. For years the Soviet space program had been hampered by the fact that he refused to go along with Sergei Korolev’s judgment that LOX and liquid hydrogen were the best fuels to use on a large rocket. The N1 accordingly had engines built by a far less experienced designer, Nikolai Kuznetsov, while Glushko focused on nitric acid and dimethylhydazine.

But while those propellants have the advantage of being dense and storable, they’re also not as powerful by weight and have the disadvantage of being a toxic disaster to clean up if a rocket fails. Furthermore, the Soviet leadership were interested in catching up with the United States in LOX/LH2 engines—the USSR had never built a large one, while the second and third stages of the Saturn V used them, as would the Space Shuttle Main Engine. Partly of his own accord but also because of this political pressure, Glushko had to concede in his ongoing argument with the eight-years-dead Korolev.

That said, he pulled it off. Over the course of the next ten years (which is long, but not too long: the Saturn V took a bit less than seven years from proposal to first launch) NPO Energiya developed the massive core stage of the rocket. The side boosters were relatively easier, being smaller and using the kind of LOX/kerosene engines that the USSR had plenty of experience with, so the entire rocket stack was ready to fly for the first time by October of 1986.

Unfortunately they didn’t have a payload for it. While there had been some problems developing the Energia, the Buran shuttle was having a far worse time of it and wasn’t anywhere near completion. Up to this point the name “Energia” had been applied to both the booster and the spaceplane taken together, but Glushko’s earlier misdirection came back to the forefront. The rocket didn’t need to wait until its other half was ready. As it entered its last year of development, the decision was made to launch it first without Buran.

Between the fall of 1985 and fall of 1986, a new payload was quickly whipped up named Polyus. It was one of Vladimir Chelomei’s Functional Cargo Blocks, repurposed from a space station module and closely related to the Zarya module of the ISS. Polyus carried a wide variety of experiments, but its main purpose was to test the Skif-DM, a 1-megawatt carbon dioxide gas laser weapon that the USSR had been working on since 1983. Retrospectively this is less alarming than it seems, as the USSR had been hammering the US over the Strategic Defense Initiative and Mikhail Gorbachev was less than keen to risk the Americans finding out that his country was countering militarily; the Reykjavik Summit had ended in October 1986 with the two countries close to radical nuclear weapons reductions, and they would conclude the INF treaty in December of 1987. Various components of the laser were deliberately left out, leaving it with only the ability to track targets, and Gorbachev is reported to have banned testing of even that during a visit to Baikonur a few days before launch. From the standpoint of the rocket, however, Gorbachev’s visit is most interesting as it led finally to the formal naming of the launcher (as distinct from the shuttle it was supposed to launch) as Energia: it was painted on its side just prior to his tour.

The General Secretary’s misgivings notwithstanding, the first launch of Energia went ahead on May 15, 1987. During the first few seconds of its flight, before it cleared the launch tower, it tilted noticeably to one side but then corrected itself when the rocket’s attitude control system kicked in at T+3 seconds. From then Energia flew beautifully, watched only by a sole Soviet MiG as from the standpoint of the ground it quickly disappeared in low-hanging cloud. Its boosters were seen to separate correctly (though for this flight and the next they were not fitted with the parachutes that would make them recoverable), and then the core stage flew out of range of even the jet watching it. Upon burning out, it released Polyus and re-entered into the Pacific Ocean, as planned.

Polyus weighed 80 tons, and so to reach its useful orbit it had to fire a small rocket engine of its own after being released. To do so it had to rotate 180 degrees, and unfortunately for it a programming error made it continue to rotate as the engine fired—deorbiting it instead of pushing it higher. It too crashed in the Pacific.

While this was an embarrassing result, the rocket itself was a complete success. Work continued on Buran and the largely completed shuttle (while flyable, at the time it could generate only enough power for one day in orbit) was mated to another Energia and launched on an unmanned mission on November 15, 1988. Again, the rocket performed admirably (with a change in its own programming to prevent the alarming blast-off tilt) and this time its payload did too: Buran landed automatically at Baikonur after two orbits, three hours and twenty-five minutes later.

So by the beginning of 1989 the Soviet Union had itself what was at the time the most powerful rocket in production, and one that hasn’t been approached closely ever since. It could launch a space shuttle with a payload similar to that of the US’ orbiters, and if used as a rocket on its own could lift 88 tonnes into low Earth orbit or 32 tonnes to the Moon (compare to 118 and 45 for the Saturn V, and 92.7 and 23.5 for the N1 it replaced). Further development was expected to push this to 100 tonnes, and work moved forward to build a dedicated cargo pod rather than the cobbled-together Polyus to lift. A smaller version of the rocket dubbed the Energia-M, with one engine and two boosters, was underway too so that smaller payloads up to 34 tonnes could be lifted more cheaply.

What happened to make it fail: Clearly the collapse of the Soviet Union was the major cause. Just as the launcher was finding its legs the security concerns of being a superpower evaporated, as did money for any large-scale scientific missions it could have supported. There was also the problem that the Zenit-derived strap-on boosters were built by a company that was now in the independent Ukraine.

Even before that, though, Energia was already suffering from a lack of missions—if you’re not going to the Moon, lifting 100 tonnes to orbit is a bit superfluous. The shuttles it was primarily designed to lift had the same flaws as the American shuttle, and didn’t have the advantage of being the country’s sole launcher of note (as the US Shuttle did prior to the Challenger explosion in 1986).

NPO Energiya’s desperation comes through when you examine some of the missions they proposed:

  • Orbiting massive lasers to deconstruct oxygen in the upper atmosphere, for the purpose of rebuilding the ozone layer over the course of several decades.
  • Using it to build a Helium-3 mining base on the Moon—bearing in mind that Helium-3 is only useful in fusion power plants being developed by an international consortium that believes they’ll be ready to go in 2050.
  • Launching spent nuclear fuel waste into “graveyard” heliocentric orbits.

Ultimately it came down to a question of what it was supposed to do that couldn’t be done by smaller, cheaper rockets—each launch of an Energia cost $US240 million, even at the more favourable black market rate of the rouble to dollar in the late 80s. Even if launches were reserved for situations where only it was capable enough, just keeping the plant in place to build it would have cost a not-so-small fortune, which the Soviet Union didn’t have and post-1991 Russia most definitely didn’t have.

What was necessary to succeed: Keep the Soviet Union a going concern. This is difficult if one subscribes to the theory that the Soviet Union collapsed primarily because of financial pressures, because you can also reasonably say that Energiya/Buran was one of the main straws breaking the camel’s back. It was representative of the unchecked spending that killed the USSR and if the only way they could have continued would have been to not do this sort of thing.

On the other hand, one can reasonably argue that it was Mikhail Gorbachev’s reaction to the country’s finances that did the worst damage, and that the USSR could have limped along into the present day if the Politburo had come up with someone other than Gorbachev as leader following Konstantin Chernenko.

That solves the major problem with a large booster—that it’s not economically feasible to run one for anything other than special purpose missions. The Soviet leadership got the USSR into financial trouble by ignoring costs when it suited them, so Energia probably would have flown every now and then until the belated collapse of this postulated Soviet Union did finally occur.

Putting aside the more radical missions mentioned above, what would Energia been used for? Likeliest would be a space station built around one or more large modules, with other smaller ones being lifted by the Energia-Buran combination. Mir-2 was redesigned to be built solely from 30-ton modules as late as 1991.

Also possible was a smaller shuttle, OK-M2, which would have perched on top of the Energia stack rather than on the side. If the USSR’s leaders had reached the same conclusion about their space shuttle as many people did about the American one, it’s entirely possible they would have scrapped Buran and its follow-up orbiters, flown Energia as a cargo rocket for a while, and developed this smaller proposed shuttle as a replacement.

Glushko’s bet that the Soviet space program would go through a future shake-up, as it had several times before, was probably a good one too. While it’s obviously more efficient to design a launcher around proposed missions, past history shows that once a system is designed people start figuring out ways to use it. With a super-heavy launcher at hand, it seems likely that the Soviet Union would have eventually got around to a Moon landing, and only somewhat less likely that they’d have moved on to a Moon base. It really would have come down to a race between deteriorating Soviet finances (assuming that they couldn’t have come up with a softer landing at some later point than actually happened ) and the time when someone with power in the Politburo and Secretariat came to champion it. It would have been expensive and somewhat pointless, but that was the USSR’s modus operandi in any number of megaprojects. As it happened, Glushko died on January 10, 1989, less than two months after the Energia’s second, and last, flight, and before his bet had a chance to pay off.

Though none of this ever came to pass, Energiya does have a continuing legacy down to the present day. The Zenit rocket that shares so much technology with the Energia’s strap-on boosters became the cheapest of all current launchers (at about US$2500 to $3600 per kilogram). In 2010 NPO Energiya bought out its partners in the Sea Launch consortium that uses them, and is now in charge of firing them from their ocean platform as well as from Baikonur in Kazakhstan.

The RD-170 engine developed for the Zenit and the Energia strap-ons have also proven to be one of the best rocket engines ever developed. Its derivatives are still used on the Zenit, on a South Korean rocket called the Naro-1, the upcoming Russian Angara rocket family, and surprisingly even on the American Atlas V, which not only launched scientific missions like the Curiosity rover and the New Horizons probe to Pluto but also is used by the US military. Such is the difference between 1988 and the present day.

YouTube video of the first Energia launch, including its alarming tilt away from the launch tower before its attitude control system kicked in, can be seen here.

SERV/MURP: Chrysler’s Space Truck

SERV-MURP

A schematic diagram of Chrysler’s SERV, an unusual VTOL Shuttle proposal to NASA in 1969-71. This is the final version, which could have mounted a crew capsule on top as shown here, or the capsule could have been swapped out for the MERP D-10, shown in the upper right. Image from the 1971 NASA document Project SERV Final Review. Click for a larger view.

What it was: A contender for the position of Space Shuttle at NASA. Unlike all the other possibilities raised during the Shuttle’s early development, it was a squat single-stage-to-orbit rocket booster that could get to orbit, release a small crew vehicle or cargo container, return to Earth ballistically, and soft-land on its original launch pad under its own power using jet engines. Both sections of the craft were reusable.

Details: A reusable Space Shuttle was originally a small part of a large post-Apollo NASA program, but over the years 1969-1971 it became progressively clearer that it was all they were going to get of that program. As a result the competition to build it was intense, with at least a dozen proposals—solicited and unsolicited—coming to them before they picked the “winged-orbiter-external-tank-two-side-boosters” approach that actually ended up getting built.

NASA had made it known that they were primarily interested in a winged orbiter, and so accordingly almost all of the proposals they received started from that base. But they didn’t explicitly rule out another approach. Chrysler produced the only notable proposal that came from outside the box.

The first iteration of the SERV/MURP came in November 1969, as part of Phase A of the competition. Chrysler had already done a lot of work for NASA, as they were the ones to build the Saturn I-C (the first and largest stage of the Saturn V), and with the Apollo program winding down they were looking to continue using the Michoud Assembly Facility in New Orleans that they’d been using to fabricate it. Their new proposal started from an interesting solution to a basic problem: two of the requirements for the shuttle, cargo capacity and cross-range capability, were at odds. Making a spacecraft better at either one would eat into the other. Chrysler’s idea was to split the two capabilities.

One module (MURP, the Manned Upper-stage Reusable Payload), was a manned orbiter outsourced McDonnell Douglas. It had a high cross-range ability but no real cargo capacity, while the other (SERV, the Single-stage Earth-orbital Reusable Vehicle) would be a single-stage-to-orbit booster with no real ability to move cross-range but with a huge cargo bay. The SERV and MURP would be mated, with the booster lifting the orbiter that was sitting on its tip. The booster would separate once in LEO, deliver its cargo, and then return to Cape Canaveral, while the orbiter could carry its people on their merry way to wherever it was they were headed—be it the proposed NASA Space Station, or to dock with injection stages headed for the Moon.

The MURP was fairly straightforward, a winged craft based on the HL-10 lifting body that NASA had been testing since 1966. There were actually two MURPs in the original proposal, one larger (the D-34) and one smaller (the D-10). The D-34 had 85 cubic meters of internal cargo space, while the smaller had only 5 cubic meters but made up the difference with a cylindrical cargo pod attached to its aft end. As the cylinder was a more efficient use of materials to enclose the space, the D-10 was considerably lighter than its bigger brother, 11,640 kilograms as compared to 16,150. Both would take two crew and carry up to ten passengers, and each had only a small amount of fuel—the SERV would get it into orbit, so it only needed to be able to go to a higher space station orbit on its own and perform a de-orbit burn. It would be covered with a spray-on silicone ablative skin (peeled off and refreshed after every trip) that would protect it from re-entry, and it would be able to land at any landing strip of reasonable length.

While the MURP was interesting, it was essentially just a very small version of what the other contenders for the Shuttle contract were proposing. Where Chrysler diverged most strongly from its competitors was with the SERV.

SERV would have been a tubby rocket, actually wider than it was tall; even with the MURP on the top of it, it would have only been 38.5 meters in height as compared to 28 meters wide.  In contrast, the actually-built Space Shuttle stack was 56.1 meters tall.

It had these measurements because it returned from orbit ballistically, and in fact resembled a gigantic Apollo capsule. This choice let the SERV benefit from the years of aerodynamic research put into that shape. Maximum heat was 1700 Celsius, on the uppermost edge of the blunt underside so it had a heat shield made of a silicone ablative material embedded in a metal honeycomb framework, individual sections of which could be swapped in and out.

Integral Aerospike Engine

The underside of the SERV, with its ablative heat shield and the aerospike engine that would fire the vehicle into orbit. Its concave profile would act as half of an exhaust bell, with the atmosphere as the other. This tuned the rocket’s performance as air pressure changed. Image from Project SERV Final Review. Click for a larger view.

To get into orbit, the SERV used another innovation, an aerospike engine. The typical exhaust  nozzle on a rocket engine is bell-shaped, which has the peculiar effect of making the engine most powerful at one particular air pressure. In other words, a rocket loses efficiency if it’s running at a height lower or higher than the one it’s tuned for—and of course an orbital rocket has to run through a whole range of heights from sea level on up. An aerospike, on the other hand, inverts the bell so that the concave curves are on the outside—now one half of the bell is solid, while the other half is formed by the atmosphere pushing against the side of the exhaust. This has the effect of continuously increasing the size of the imaginary bell as air pressure drops, an on-the-fly reconfiguration that keeps the efficiency of the engine up. On top of that, the SERV engine was going to be extremely powerful: 32 kilonewtons of force, compared to the actual Space Shuttle’s SSMEs at 1.9 kN (of which the Shuttle Orbiters had three), or even the most powerful liquid fuelled engines ever built, the Energiya rocket’s RD-170 at 7.9kN.

As a result it was so powerful that it could get into orbit by itself, even with the dead weight of a MURP attached to the top of it. In all it could lift as much as 39 tonnes to LEO with its single stage, about 40% of what the far more massive Saturn V could do. By the time of the Phase B proposal in 1971, Chrysler tried to make the SERV more attractive by adding to the possible modules that could be mated to its top. As well as a MURP they came up with a ballistic passenger capsule similar in size and shape to an Apollo CM (which was cheaper and smaller than even a D-10, and so the SERV could lift even more cargo), a high fineness ratio nose spike that would make an unmanned version of the craft more aerodynamic so that it could lift even more, and finally a nuclear-rocket launched upper stage that would be perfect for heavy Moon missions or manned trips to Mars.

On its ballistic return to earth the SERV could aim for an area about 15 kilometers in diameter, but unfortunately that was not accurate enough to meet NASA’s requirements. Undaunted, Chrysler proposed to put a ring of 28 jet engines with associated air intake doors around the edge of the SERV’s tubby body, inside its fairing so their profile wouldn’t disturb the booster’s smooth aerodynamics. These would kick in at 7600 meters of altitude, gulping air for oxidizer (and saving some weight by doing so, rather than using liquid oxygen) and push the SERV even closer to its goal. It could even hover for as long as its jet fuel held out. With the aid of the jets, it could get to within 75 meters of its aim point. Two special landing pads would have been built at Cape Canaveral right next to maintenance buildings on the shore of the Banana River so that returning SERVs could be whisked in for a post-mission checkup and refurbishment.

With that kind of performance, Chrysler pointed out in its Phase A proposal that the SERV would be within striking distance of providing a commercially viable suborbital “space airline” between major cities. Almost anywhere on Earth was forty minutes away. The main stumbling block was the cost of fuel, which brought the cost of a ticket to about US$33,000 (in 1969 currency). Chrysler somewhat arbitrarily felt that fuel costs would drop by three-quarters given the volumes that would be made to accommodate NASA’s requirement that any Shuttle would have to fly at a punishing schedule of roughly three times per month. Under those circumstances per-person costs would be only about US$10,900

If given the contract on January 1, 1973, Chrysler anticipated that the SERV/MURP’s first test flight would be towards the end of 1977, with the first operational flight in the first quarter of 1978. The total cost of flying four SERVs with three MURPs was pegged at US$10.01 billion, including operations through the end of 1986.

What happened to make it fail: The SERV, as proposed, had a number of small advantages over the spaceplanes that were submitted to NASA in the Shuttle competition, so it’s a little surprising that it got no traction at all. While it did make it through the Phase A first cut and into Phase B, it was never seriously considered.

The reason for this is speculative as it was the sort of thing that doesn’t get much documentation. Any project at NASA needed a broad constituency, and the SERV failed to make it off the drawing board because its peculiarities turned every possible supporter against it. NASA’s management had come to the conclusion that a large spaceplane was the way to go, and had only allowed other arrangements as a sop to due diligence. NASA’s astronauts didn’t like that the SERV (as ultimately envisioned in the Phase B proposal) could fly unmanned, cargo-only missions. And NASA engineers were concerned about the SSTO/Aerospike engine approach, which is very sensitive to weight and thrust. Marginal failures to meet the proposed engine characteristics or rocket weight can radically reduce the payload that can be carried to LEO, or even keep the craft from reaching orbit at all.

What was necessary for it to succeed: Besides its lack of support, the marginal failures just mentioned were the biggest problem the SERV/MURP had. As proposed, it looks a lot better than the Shuttle that was actually built, but of course the proposals for the actual Shuttle were far more comparable. Besides the aerospike engine, the SERV/MURP needed a number of technologies that were less well worked out than what went into the real Shuttle. If the real Shuttle went over time (it did, by several years) and budget (it did, by about a billion dollars) during development, what would have happened to the SERV, which even in its proposal was going to be more expensive and take longer? The MURP relied on an ablative coating technique that had been a near disaster the one time it was used, on X-15A-2, when that craft was nearly lost due to its ventral stabilizer nearly burning off. The SERV was enormously larger than an Apollo capsule—was it wise to be sure that it would have a similar heating profile?

Ultimately it’s impossible to be sure. It’s easy to take NASA to task for picking a conservative design that ended up being a far more marginal spacecraft than they had hoped, but the fact remains that with similar bad luck on the SERV they could have ended up with something that couldn’t fly at all—and they were being asked to spend the majority of their budget on it for a number of years. As they didn’t have the benefit of hindsight, it becomes easy to see why they went for the more conservative approach.

So to get the SERV to fly you need to make it so that it’s the less radical of the two options. The large winged orbiter of the Space Shuttle had the advantage of years of aerodynamic and thermal studies on other planes, such as ASSET/PRIME, the X-15, the HL-10, and the X-24A. Eliminate that and the orbiter suddenly becomes an unknown, at which point the SERV mated to a ballistic crew capsule (rather than the MURP) starts looking a lot more attractive.