Saturday Night Science: Energiya-Buran

 

“Energiya-Buran” by Bart Hendrickx and Bert VisThis authoritative history chronicles one of the most bizarre episodes of the Cold War. When the US Space Shuttle program was launched in 1972, the Soviets, unlike the majority of journalists and space advocates in the West who were bamboozled by NASA’s propaganda, couldn’t make any sense of the economic justification for the program. They crunched the numbers, and they just didn’t work—the flight rates, cost per mission, and most of the other numbers were obviously not achievable.

So, did the Soviets chuckle at this latest folly of the capitalist, imperialist aggressors and continue on their own time-proven path of mass-produced low-technology expendable boosters? Well, of course not! They figured that even if their wisest double-domed analysts were unable to discern the justification for the massive expenditures NASA had budgeted for the Shuttle, there must be some covert military reason for its existence to which they hadn’t yet twigged, and hence they couldn’t tolerate a shuttle gap and consequently had to build their own, however pointless it looked on the surface.

And that’s precisely what they did, as this book so thoroughly documents, with a detailed history, hundreds of pictures, and technical information which has only recently become available.

The most striking thing about the Buran orbiter is that it is almost identical in size and configuration to the US Space Shuttle orbiter, to such an extent that some wags called it “Shuttleski,” and it was widely assumed to be a direct copy of the US design. In fact, the story is quite a bit more complicated and interesting. Recall the rationale for the program: the Soviets did not want the US to develop a space operations capability which they lacked. Consequently, the design goals of the Soviet shuttle would have to equal or exceed those of the US craft in order to accomplish the same mission (whatever that might be). This dictated payload bay size and mass capability, orbital inclinations and altitudes accessible, and cross-range capacity (the ability to land at locations far from the orbital track by maneuvering in the atmosphere). These requirements could only be met by a vehicle with high wing loading (to achieve the large cross-range), which in turn meant a hot reentry, necessitating a thermal protection system able to take the heat.

Putting all of this together and given the materials technology available at the time, any design which duplicated the capabilities of the US shuttle was likely to strongly resemble it, even if it were a clean sheet design. But the Soviet engineers didn’t have to start with a clean sheet, and no espionage was required. NASA was very open about the design and development of the shuttle, and extensive information about its specifications, design, development, and component testing was available in the open literature. Since the US went first, the Soviets could examine this material and pick and choose aspects of it for their own design. Here is a detailed discussion of the differences between the US and Soviet orbiters on buran.su.

Despite the similarity in appearance of the orbiters, the complete systems were very different. The US space shuttle orbiter had three main engines powered by liquid hydrogen and liquid oxygen (LH₂/LOX) stored in a large external fuel tank which was discarded upon reaching orbital altitude and broke up upon re-entry, with debris falling in the Indian or Pacific Oceans depending upon the launch trajectory. For the first two minutes of flight, most of the thrust was provided by two solid rocket boosters mounted to the sides of the external tank. After burning out, the boosters were jettisoned and parachuted to the Atlantic, where they were recovered by ships and returned to the launch site for inspection, refurbishment, and re-use.

The US shuttle was an integrated system in which all components (orbiter, external tank, and solid rocket boosters) were developed specifically for the shuttle and had no other applications. Payloads were carried in the 18-meter-long payload bay (sized to accommodate the largest reconnaissance satellites envisioned at the time of its specification) and, depending upon the orbit required, could be up to 27.5 tonnes in mass. (On missions to the International Space Station, with a high inclination and orbital altitude, payload was reduced to 16 tonnes.)

The Soviet Buran orbiter, by comparison, was a payload carried by Energiya, a general purpose heavy-lift launcher capable of carrying a variety of payloads in addition to the shuttle. Energiya was composed of a core stage burning LH₂/LOX in four RD-0120 engines which were comparable in performance, although less complicated, less expensive, and heavier than the US shuttle’s main engines. These were the first large liquid hydrogen engines developed by the Soviets. Four boosters were attached to the core stage, each burning kerosene and liquid oxygen in an RD-170 engine. (The RD-180 engine used on the US Atlas V launcher, which has been the subject of recent controversy, is a less powerful version of the RD-170.) The boosters and core stage are all ignited for liftoff. After 140 seconds, the boosters burn out and are jettisoned, while the core stage and payload attached to its side continue on to space. The boosters were designed to be recovered for reuse by means of parachutes and a retro-rocket for landing, but this system was not installed for the initial flights and the boosters were expended. Energiya was able to place payloads of up to 100 tonnes in low Earth orbit (again, depending upon the parameters of the required orbit). After separating from the core stage, the payload was responsible for providing its own propulsion. Third stages were envisioned for launches to geostationary orbit, the Moon, or the planets, but these were never developed.

The Buran orbiter was simply one of the payloads which Energiya could carry. Unlike the US shuttle, it had no main engines, just orbital maneuvering engines which were used to circularize its orbit, make orbital adjustments for rendezvous with space stations or satellites, and de-orbit at the end of the mission. This architecture meant that the four engines on the core stage were expended on every mission, unlike the three main engines which were returned with the US orbiter. The economics of this are unclear. Refurbishment of the space shuttle main engines was complex, time-consuming, and expensive. Further, the engines themselves were more complicated and expensive due to the requirement of re-use. Energiya’s core stage engines could be designed for a single run of less than 10 minutes, which simplified the design and reduced costs. Buran’s payload size and mass were comparable to the US shuttle. Buran could fly autonomously without a crew.

The Soviet shuttle had a number of advantages over the US design. First among these was the ability to use the Energiya booster without the orbiter as an unmanned cargo launcher. In this mode it could launch payloads with around four times the mass of those which could be carried in the US shuttle’s payload bay, and carry them without the need to put a crew at risk. This capability would have been ideal for launching space station modules, large reconnaissance and communication satellites, and interplanetary science missions. On such missions, the US shuttle spent three quarters of its payload capacity on wings and wheels which weren’t used except in the last minutes of the mission, and life support and facilities for a crew which had little to do with regard to the payload other than push a button to release it.

Unlike the US shuttle’s solid rocket boosters which, once lit, could not be throttled or shut down, Energiya’s four liquid boosters could be throttled to adjust acceleration for the mission profile and cut off in emergency situations, increasing the survivability of launch accidents. Had the anticipated recovery and reuse of the boosters worked, it would probably have been much more cost effective than fishing solid boosters out of the sea and refurbishing them.

Unlike the US shuttle, which was sold to Congress and the Air Force on the basis of a promise to replace all existing expendable launchers and dramatically reduce the cost of launching payloads, Energiya was seen as a heavy-lift launcher which would be reserved for payloads which required its unique capabilities and Buran for crewed missions to assemble and maintain space stations and change out their crews.

Energiya-Buran was one of the most ambitious and magnificent engineering projects of the space programs of any nation, involving massive research and development, manufacturing, testing, integrated mission simulation, crew training, and flight testing programs.

The program came to a simultaneously triumphant and tragic end: the Energiya booster and the Energiya-Buran shuttle system performed flawless missions. (The first Energiya launch failed to put its payload into orbit, but this was due to a software error in the payload [Polyus].) On November 15, 1988, the second Energiya launched Buran (OK-1K1) into orbit. No crew was on board: the mission was flown by the orbiter’s computers. After maneuvering to a higher orbit, two orbits were completed, and then the maneuvering system was used to de-orbit. An autonomous re-entry was flown, with a perfect landing on the runway at Baikonur Cosmodrome despite a strong crosswind.

And then, in the best tradition not only of the Communist Party of the Soviet Union but of the British Conservative Party in 1971, this singular success was rewarded by cancellation of the entire program. Energiya never flew again. Buran was destroyed in 2002 when the roof of the hangar in which it was being stored collapsed.

As an engineer, I have almost unlimited admiration for my ex-Soviet and Russian colleagues who did such masterful work and who will doubtless advance technology in the future to the benefit of us all. We should celebrate the achievement of those who created this magnificent space transportation system, undone by the collapse of a fatally flawed and destructive economic and political system.

Hendrickx, Bart and Bert Vis. Energiya-Buran. Chichester, UK: Springer Praxis, 2007. ISBN 978-0-387-69848-9.

Here is a documentary about the Energiya-Buran program with film which only became available after the collapse of the Soviet Union. The narration is in heavily accented English, overdubbed in French. Sorry—one must work with what’s available.

Here is a silent video with other launch views of Energiya-Buran.

The following videos, with tacky music, show Energiya and Buran footage I’ve not seen elsewhere.

Part 1:

Note how the first launch of Energiya with Polyus almost ended badly when it veered off course moments after liftoff. Got better!

Part 2:

Spaceplane orbital bombardment!

There are 47 comments.

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  1. Gary McVey Contributor

    John, didn’t Buran have air breathing engines so it could “loiter”, i.e. didn’t have to rely on unpowered glide back to a landing? It’s interesting how some of these key decisions were made differently.

    • #1
    • March 12, 2016, at 11:06 AM PDT
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  2. John Walker Contributor
    John Walker Post author

    Gary McVey:John, didn’t Buran have air breathing engines so it could “loiter”, i.e. didn’t have to rely on unpowered glide back to a landing? It’s interesting how some of these key decisions were made differently.

    During the development and test phase, Buran was equipped with four turbojet engines which allowed to take off under its own power. It could then attempt dead-stick landings to see if they were viable, while retaining the option to throttle up the engines and go around in case of a missed approach.

    NASA, instead, conducted Approach and Landing Tests in which the shuttle pathfinder Enterprise was released from the 747 Shuttle Carrier Aircraft to glide to a landing. In the NASA tests there were no engines on the shuttle and no possibility of a go-around, but the tests were conducted at Edwards Air Force Base, where the dry lake provides an enormous landing area.

    Early in the development phase of the Shuttle, NASA considered equipping it with deployable jet engines for landing, but based upon experience from the X-15 and lifting body programs concluded that precision dead-stick landings were feasible. The Soviets came to the same conclusion, no doubt helped by seven years of NASA experience before the first flight of their own shuttle.

    Here is video of the first U.S. shuttle approach and landing test.

    • #2
    • March 12, 2016, at 11:48 AM PDT
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  3. Gary McVey Contributor

    I understand Russian defensiveness about Buran’s similarities to the US shuttle–certainly, as you point out, certain fundamental design parameters made outcomes like a delta wing for crossrange make the final product look deceptively alike.

    But let’s be honest, fellow Yanks–in 1988, when you first saw photos of Buran, wasn’t your first immediate reaction one of laugh-out-loud astonishment?

    • #3
    • March 12, 2016, at 11:57 AM PDT
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  4. Mark Wilson Member

    John Walker: These requirements could only be met by a vehicle with high wing loading (to achieve the large cross-range)

    John, can you expand on why high wing loading is necessary for cross range divert? Intuitively low wing loading seems to provide the longest endurance and therefor glide range.

    • #4
    • March 12, 2016, at 12:04 PM PDT
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  5. John Walker Contributor
    John Walker Post author

    Gary McVey: But let’s be honest, fellow Yanks–in 1988, when you first saw photos of Buran, wasn’t your first immediate reaction one of laugh-out-loud astonishment?

    The loudest laughs I recall were from people who had long been laughing at the “gigantism” of the NASA shuttle design, motivated by the Air Force and NRO payload size and mass requirements and promoting the shuttle to replace all expendable launch vehicles, upon seeing that the Soviets had precisely mimicked its (ridiculous) design specifications. NASA wanted to build a much smaller shuttle, more reusable, with less cross-range and wing loading, primarily as a crew transport. They were forced into the design they ended up building because the only way they could sell it was as a replacement for all existing launchers, so they were forced to size it handle Titan payloads. Budget constraints forced a design which was only partly reusable and required extensive refurbishment between flights.

    • #5
    • March 12, 2016, at 12:05 PM PDT
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  6. John Walker Contributor
    John Walker Post author

    Mark Wilson:

    John Walker: These requirements could only be met by a vehicle with high wing loading (to achieve the large cross-range)

    John, can you expand on why high wing loading is necessary for cross range divert? Intuitively low wing loading seems to provide the longest endurance and therefor glide range.

    My understanding is that the Shuttle’s delta wing design and high loading was driven by the Air Force requirement to land at the launch site after a one-orbit polar orbit mission, which required a cross-range of 2000 km. Earlier NASA thinking leaned toward a smaller orbiter with straight wings and lower wing loading. These designs would have lost energy more rapidly during re-entry, with less heating of the structure and requirement for thermal protection. But, as I understand it, the problem is that by the time you’ve become an atmospheric glider, your energy (airspeed and altitude) isn’t enough to meet the cross-range requirement.

    The only way to obtain the cross-range is to perform most of it at hypersonic speeds, which requires a large wing, which implies a large heat pulse, and hence the need for the fragile tile and reinforced carbon-carbon composite thermal protection system.

    • #6
    • March 12, 2016, at 12:21 PM PDT
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  7. Judge Mental Member

    John Walker: Earlier NASA thinking leaned toward a smaller orbiter with straight wings and lower wing loading.

    There are only a couple of brief glimpses here, but this famous bit of video shows an earlier and smaller design. The original thought was a truncated cone, split longitudinally.

    (BTW, the actual pilot received only minor scrapes and bruises.)

    • #7
    • March 12, 2016, at 12:31 PM PDT
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  8. Seawriter Member

    John Walker: My understanding is that the Shuttle’s delta wing design and high loading was driven by the Air Force requirement to land at the launch site after a one-orbit polar orbit mission, which required a cross-range of 2000 km.

    Pretty much. I covered a lot of this in my book about the Shuttle, which was basically a history of the Air Force use of the Shuttle. The major requirements defining the Shuttle were (a) the ability to launch a Keyhole satellite into a sun-synchronous orbit, and (b) the ability to rendezvous with a satellite in any orbit, put it in the cargo bay, and land all in one revolution from launch to landing – and land in the continental US.

    This involved launching from and landing at Vandenberg Air Force Base to a polar orbit. Since the landing site would have moved 1200 miles east during one rev, the Shuttle needed at least that much crossrange, with a 50% margin “just in case.” This dictated the double-delta wing design. Straight wings had only a 300 mile crossrange. It also dictated segmented SRBs as monolithic solids could not negotiate a railroad tunnel leading to Vandenberg. The double-delta wing and the segmented SRBs were the proximate cause of both fatal Shuttle missions.

    The irony was neither a Keyhole satellite launch nor one-rev satellite snatch was ever done with a Shuttle.

    Seawriter

    • #8
    • March 12, 2016, at 1:02 PM PDT
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  9. Grosseteste Member

    Judge Mental:There are only a couple of brief glimpses here, but this famous bit of video shows an earlier and smaller design. The original thought was a truncated cone, split longitudinally.

    (BTW, the actual pilot received only minor scrapes and bruises.)

    I thought that the failure of that design led to a mission built around a manned multi-stage rocket:

    • #9
    • March 12, 2016, at 2:09 PM PDT
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  10. Judge Mental Member

    Grosseteste:I thought that the failure of that design led to a mission built around a manned multi-stage rocket:

    I was actually being serious. John’s exposition filled in some blanks for me. That footage comes from a real test, I guess you could call it a proof of concept, but they were far enough along that it was a manned test. The requirements John described finally made sense for me how they got from this little puppy to the eventual design.

    • #10
    • March 12, 2016, at 2:15 PM PDT
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  11. John Walker Contributor
    John Walker Post author

    Judge Mental:

    John Walker: Earlier NASA thinking leaned toward a smaller orbiter with straight wings and lower wing loading.

    There are only a couple of brief glimpses here, but this famous bit of video shows an earlier and smaller design. The original thought was a truncated cone, split longitudinally.

    (BTW, the actual pilot received only minor scrapes and bruises.)

    The crash shown in the introduction The Six Million Dollar Man was that of the Northrop M2-F2 lifting body on May 10th, 1967. While landing after a glide test, pilot Bruce Peterson encountered stability problems and tried to avoid a helicopter which he believed posed a collision threat. The result was the crash and roll-over shown in the film. Peterson was severely injured and lost the sight in one eye. After recovering, he resumed his flying career until his retirement in 1981. He died in 2006.

    Here is a full video of the accident.

    The lifting bodies were high loading devices (you can’t say “wing loading” since they didn’t have wings), and their success in making precision dead-stick landings helped to convince NASA that the Shuttle could land without engine power.

    • #11
    • March 12, 2016, at 2:25 PM PDT
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  12. Yuma93 Member

    John Walker:The loudest laughs I recall were from people who had long been laughing at the “gigantism” of the NASA shuttle design, motivated by the Air Force and NRO payload size and mass requirements and promoting the shuttle to replace all expendable launch vehicles, upon seeing that the Soviets had precisely mimicked its (ridiculous) design specifications.

    Worse yet, the Buran had to stop in Shannon and Gander when flying from Moscow to JFK.

    • #12
    • March 12, 2016, at 2:28 PM PDT
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  13. Kevin Creighton Contributor

    One good thing to come out of Energiya/Buran was the An-225 cargo plane, the Rooskies version of the Shuttle Carrier Aircraft.

    It holds multiple records for aircraft cargo hauling and has been used several times to move cargo to the troops in Iraq. May not be the most beautiful aircraft in the skies, but when you have something really heavy that absolutely positively has to be flown around the world, it’s the plane you want.

    • #13
    • March 12, 2016, at 2:58 PM PDT
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  14. ctlaw Coolidge

    The Shuttle was deeply flawed.

    First, reusability was overestimated.

    Second, the main advantage of a shuttle is in bringing big things back from orbit not in taking things to orbit, yet the latter was a near exclusive use. In this regard, Buran had the advantage of not needing to return the weight of the engines.

    • #14
    • March 12, 2016, at 3:07 PM PDT
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  15. Judge Mental Member

    John Walker: Peterson was severely injured and lost the sight in one eye.

    Hazard of trying to remember from a film in junior high.

    • #15
    • March 12, 2016, at 3:08 PM PDT
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  16. Gary McVey Contributor

    I’ve tended to go by T. A. Heppenheimer’s multi-volume history of the Shuttle, which doesn’t go into Buran’s development. But I agree with the other commenters here: it was sold to the Nixon administration on the basis of lowering costs drastically, and that was only possible by falsely assuming an unrealistic number of launches to amortize development, and that was only possible by the artificial means of giving it a near-monopoly on orbital launch.

    It must be said it did work. But it was like Concorde, or the first generation of nuclear electric generating plants; it worked but it wasn’t robust and it was wildly more expensive than promised.

    • #16
    • March 12, 2016, at 3:21 PM PDT
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  17. John Walker Contributor
    John Walker Post author

    ctlaw: In this regard, Buran had the advantage of not needing to return the weight of the engines.

    Yes, by expending the engines on the Energiya core stage, Buran had an estimated up-mass of several tonnes greater than the U.S. space shuttle. This would have also increased the down-mass although, as you note, this was rarely a constraint in the U.S. shuttle program.

    (I think there were shuttle missions where if ISS modules or heavy satellites could not have been delivered, they would have to have been abandoned in orbit because they were too heavy to return with, but I haven’t done detailed research on this.)

    • #17
    • March 12, 2016, at 3:24 PM PDT
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  18. John Walker Contributor
    John Walker Post author

    Gary McVey: I’ve tended to go by T. A. Heppenheimer’s multi-volume history of the Shuttle, which doesn’t go into Buran’s development.

    I also recommend Dennis Jenkins’ Space Shuttle: The History of the National Space Transportation System. This delves deeply into the evolution of the shuttle, from original fully-reusable concepts to what actually got built. I read the earlier edition of this book, which covers missions through 1993.

    • #18
    • March 12, 2016, at 3:31 PM PDT
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  19. Seawriter Member

    John Walker: (I think there were shuttle missions where if ISS modules or heavy satellites could not have been delivered, they would have to have been abandoned in orbit because they were too heavy to return with, but I haven’t done detailed research on this.)

    No. Any such mission could not perform either a Trans-Atlantic-Landing or an Abort-Once-Around contingency landing. In both scenarios the payload bay doors do not open long enough to eject the cargo. (Don’t remember if they do open.) No Shuttle mission through mission 25 (51-L, Challenger) carried a cargo too heavy to land with. (I was part of the Mission Control teams on those flights.)

    After Challenger, NASA was not prepared to fly a Shuttle mission without a TAL or AOA capability. Missions where the Orbiter launched with a payload too heavy to land with may have drawing-board missions, but NASA never flew any.

    The only missions with overweight payloads involved the liquid-fueled Centaur upper stages. In those missions, abort scenarios called for dumping fuel (which would have brought the Orbiter down to landing weights before the main gear touched down) during the abort phase. Touchdown weight was not the issue. The problem with those missions is during a Return-to-Launch-Site abort the tanks would not yet be empty, and still venting LOX/LH2 after the Orbiter rolled to a stop. Fuel-air explosion anyone? Those missions were cancelled after Challenger.

    Seawriter

    • #19
    • March 12, 2016, at 4:14 PM PDT
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  20. John Walker Contributor
    John Walker Post author

    Seawriter: No Shuttle mission through mission 25 (51-L, Challenger) carried a cargo too heavy to land with.

    According to the always-authoritative Wikipedia (cough), the Chandra X-ray Observatory, launched by STS-93 on 1993-07-23, weighed 22,753 kg in the payload bay, thanks to its two-stage IUS booster rocket plus the payload.

    According to the Wikipedia page on the Space Shuttle, maximum downmass is 14,400 kg. Is the limit greater on a TAL or AOA? I don’t know; I’m just asking.

    • #20
    • March 12, 2016, at 4:38 PM PDT
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  21. John Walker Contributor
    John Walker Post author

    Yasha: Worse yet, the Buran had to stop in Shannon and Gander when flying from Moscow to JFK. :-)

    Heh. The British Airways BA001 flight from London City (LCY) to JFK in New York stops in Shannon to refuel because due to the short runway at LCY and headwinds westbound they can’t take off with enough fuel for the transatlantic flight. Passengers are pre-cleared through U.S. customs and immigration during the stop in Shannon, and arrive in New York as on a domestic flight. It is absurdly expensive, although not as much as the Concorde which previously flew BA001.

    • #21
    • March 12, 2016, at 5:19 PM PDT
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  22. Gary McVey Contributor

    The most sensible course would probably have been to support expendables right through the Seventies and Eighties, but develop an experimental reusable spaceplane that could be launched with existing expendable boosters; less crossrange, less cargo capacity to orbit, but fewer eggs in one basket. Work the hell out of Mark I, learn a few lessons, get a Mark II going for the mid-to-late Eighties, and if it delivers economically, go for the definitive Mark III around 2001-02; the real DC-3 of space, not the DC 1 1/2 we ended up with.

    • #22
    • March 12, 2016, at 5:47 PM PDT
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  23. Seawriter Member

    John Walker: According to the Wikipedia page on the Space Shuttle, maximum downmass is 14,400 kg. Is the limit greater on a TAL or AOA? I don’t know; I’m just asking.

    Should not be. Downmass is a function of the Orbiter’s landing gear. Downmass varied from Orbiter to Orbiter as each had a different mass. The downmass listed on Wikipedia might be for Columbia, which was the heaviest Orbiter. Even at that I would wonder about the accuracy, especially since Columbia flew that mission. The number I heard was 35,000 pounds mass which is 15,875 kg.

    It is possible NASA reduced maximum payload downmass after Columbia in 2002. They became increasingly conservative, placing crew safety as the highest priority. The final Hubble maintenance mission was almost canceled because there was no way to rescue the crew if the wing glove were damaged. The chances of that were extremely low, but NASA was determined not to lose another crew under any circumstances.

    In 1999 I cannot see NASA launching a mission which could not land following an abort due overweight. In 1985, yeah – the program was doing increasingly risky things. After Challenger? I don’t see it. (I was absent from the Shuttle program between 1994 and 2002, so I cannot speak from being there.)

    Seawriter

    • #23
    • March 12, 2016, at 6:00 PM PDT
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  24. Gary McVey Contributor

    I took a look at the Amazon listings for your book, Seawriter. It sounds very interesting.

    The X-37B program is probably the best present-day example of what this here total layman thinks should have happened in the Seventies. Imagine a “Gemini” X-37, an enlarged version of the unmanned automated plane we have now, but initially carrying a two man crew, expandable to four. No shuttle-style two-three week missions; life support for a week. Mark II would have a service module for extended use (but be a heavier lift.) Launches from existing boosters.

    Wheels and wings, but for a price, and not for every manned mission; maintain proven, amortized capsule capability as the main method of routine manned access to space.

    • #24
    • March 12, 2016, at 7:29 PM PDT
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  25. BrentB67 Inactive

    A good friend, Tom Henricks, flew four shuttle missions, two as MC. We used to get coffee a couple times each month and he would tell stories. Once we went over the engine failure procedures on launch. Amazing what they had to know. If you want to watch a spectacular video search YouTube for the videos from the HD cameras on the nose of the solid rocket boosters from launch until splashdown. There is also a PBS documentary on how the boosters were recovered.

    I recall the math on the solid rocket boosters and their net contribution to liftoff differently, but that is past conversations over coffee and I may have the numbers/relationship incorrect.

    • #25
    • March 13, 2016, at 6:10 AM PDT
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  26. John Walker Contributor
    John Walker Post author

    BrentB67: I recall the math on the solid rocket boosters and their net contribution to liftoff differently, but that is past conversations over coffee and I may have the numbers/relationship incorrect.

    The three Space Shuttle Main Engines each produced a sea level thrust of 418,000 pounds (1860 kN) for a total thrust of 1,254,000 pounds (8880 kN). The solid rocket boosters each produced 2,800,000 pounds (12,500 kN) thrust at liftoff for a total thrust of 5,600,000 pounds (25,000 kN). Total liftoff thrust was thus 6,854,000 pounds, of which 81% was provided by the solid rocket boosters.

    During flight, the main engines were throttled down to reduce aerodynamic forces as the vehicle went supersonic and the thrust curve of the solid boosters was also tailored to provide maximum thrust at liftoff and reduced thrust as the vehicle ascended and got lighter, so the percentage of thrust provided by the solids and main engines varies during ascent.

    • #26
    • March 13, 2016, at 6:33 AM PDT
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  27. BrentB67 Inactive

    John Walker:

    BrentB67: I recall the math on the solid rocket boosters and their net contribution to liftoff differently…

    The three Space Shuttle Main Engines each produced a sea level thrust of 418,000 pounds (1860 kN) for a total thrust of 1,254,000 pounds (8880 kN). The solid rocket boosters each produced 2,800,000 pounds (12,500 kN) thrust at liftoff for a total thrust of 5,600,000 pounds (25,000 kN). Total liftoff thrust was thus 6,854,000 pounds, of which 81% was provided by the solid rocket boosters.

    During flight, the main engines were throttled down to reduce aerodynamic forces as the vehicle went supersonic and the thrust curve of the solid boosters was also tailored to provide maximum thrust at liftoff and reduced thrust as the vehicle ascended and got lighter, so the percentage of thrust provided by the solids and main engines varies during ascent.

    The way I remember the relationship, again this is several years back coffee talk, is the the thrust curve of the solid rocket boosters was tailored to lift the external tank as it provided fuel to the orbiter’s main engines.

    Something about the relationship of how the external tank married the orbiter that it was not a load bearing design wherein the thrust from the solids through the tank accelerated the orbiter. I thought it was more balanced.

    The orbiter few itself to orbit and the rest of the package supported that effort or something.

    • #27
    • March 13, 2016, at 6:41 AM PDT
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  28. John Walker Contributor
    John Walker Post author

    BrentB67: If you want to watch a spectacular video search YouTube for the videos from the HD cameras on the nose of the solid rocket boosters from launch until splashdown. There is also a PBS documentary on how the boosters were recovered.

    This is the NASA “Riding the Booster” video, showing views from cameras on both boosters, with enhanced audio by Skywalker Sound. Note how residual fuel burns due to heating as the booster re-enters the atmosphere.

    Here is left SRB aft camera video from STS-135, the last flight of the shuttle.

    This is a NASA documentary about recovery of the solid rocket boosters.

    • #28
    • March 13, 2016, at 6:51 AM PDT
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  29. John Walker Contributor
    John Walker Post author

    BrentB67:

    The way I remember the relationship, again this is several years back coffee talk, is the the thrust curve of the solid rocket boosters was tailored to lift the external tank as it provided fuel to the orbiter’s main engines.

    Something about the relationship of how the external tank married the orbiter that it was not a load bearing design wherein the thrust from the solids through the tank accelerated the orbiter. I thought it was more balanced.

    The orbiter few itself to orbit and the rest of the package supported that effort or something.

    This is the thrust profile of the solid rocket boosters:

    Thrust profile of Space Shuttle solid rocket boosters

    The propellant grain was shaped to provide maximum thrust in the early part of the flight, tapering off near the point of maximum dynamic pressure, then increasing again as the stack left the atmosphere, and finally reducing smoothly to limit acceleration as the vehicle became lighter as fuel was burned.

    The external tank is the structural backbone of the shuttle, containing the beams which transmit the thrust from the solid rocket boosters to the orbiter through its attach points. The solids provided the majority of thrust to the stack until the thrust tail-off which began at around the 110 second point.

    • #29
    • March 13, 2016, at 7:06 AM PDT
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  30. ctlaw Coolidge

    John Walker: The external tank is the structural backbone of the shuttle, containing the beams which transmit the thrust from the solid rocket boosters to the orbiter through its attach points. The solids provided the majority of thrust to the stack until the thrust tail-off which began at around the 110 second point.

    But I think Brent’s issue was what was the net force transmitted between the tank and the orbiter during ascent.

    If the SRBs are lifting their own weight plus that of the tank (and addressing their drag) and the main engines are lifting the orbiter’s weight, you could have a very low net force being transferred.

    • #30
    • March 13, 2016, at 7:25 AM PDT
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