设计得最糟糕的火箭是什么?

【前言:我在Quora上看到这个问题,觉得很有趣,想要翻译一下。并未得到授权,但反正我网站没人看,管他呢。嗯,90%是google翻译…】

The most obvious answer is, of course, the Space Shuttle.

答案很显然,航天飞机。

That’s right, I said it. No other vehicle in the history of manned space travel has lost two full crews during flight.[1] The whole design is an abomination of committee-designed inefficiencies right from the start. Even Wernher von Braun thought it was an absolutely awful design[2].

没错。没有其他的人造航天器在飞行时像航天飞机这样损失了两班宇航员。整个设计一开始就被委员会嫌弃,连  Wernher von Braun 也认为这个设计很不好。

Start with the original design which was a delta-winged “space plane” at the top of a Saturn V like rocket, comparable to the X-20 DynoSoar project. This design, known as “on-axis” means that the shuttle sits at the top, safe from exhaust blasts and debris from launch, and all of its surfaces except the un-exposed tail-end are free to be designed however is needed for space-flight and re-entry.

最早的设计是在土星5号上类似火箭的三角翼“太空飞机”,与 X-20 DynoSoar 相当。这种被称为“同轴”的设计让航天飞机位于顶部,可以安全地防止排气爆破和发射时产生的碎屑,并且除未暴露的尾端外,其所有表面都可以自由设计,并且在太空飞行和再入大气时确实需要重新设计。

【译者注:Boeing X-20 Dyna-Soar,是用来执行军方任务的“太空飞机”。项目从1957年持续到1963年,后因为航天飞船项目开始而被取消。】

The DynoSoar had its issues though, and it was never launched in an actual rocket configuration. Several of the test pilots quit the program after the Air Force squabbled about which booster to use, including one named Neil Armstrong.

虽然DynoSoar遇到了问题,但从未在实际的火箭中发射过。在空军为使用哪种助推器后争论不休时,一些等待测试的飞行员退出了该计划,其中一名叫尼尔·阿姆斯特朗。

But the design was basically a good one. Von Braun had proposed a shuttle, but his design was more like what we see with Virgin Galactic’s Space Ship Two design, with a carrier that takes the shuttle into the stratosphere, where the main shuttle engines then ignite to carry it to orbit. In von Braun’s plan, the entire system was reusable.

但是设计还是很好的。冯·布劳恩曾提议过航天飞机,但他的设计更像我们在维珍银河太空船二号设计中所看到的那样,它的运载工具将航天飞机带入平流层,然后主航天飞机的发动机点火,将其送入轨道。在冯·布劳恩(von Braun)的计划中,整个系统是可重用的。

That, however, didn’t make Congress and the companies like Boeing and Lockheed very happy. Re-usable meant they couldn’t sell you a new $100,000,000 rocket engine on every flight. Re-usable meant that assembly jobs were a one-time thing, and then congressional districts lost jobs and money. On the other hand, expendable meant the gravy train kept running.

但是,那并没有使国会以及波音和洛克希德等公司感到非常高兴。可重复使用意味着他们无法在每次飞行中向您出售新的价值100,000,000美元的火箭发动机。可重复使用意味着组装工作是一次性的,然后那些工人将会丢掉了工作和金钱。另一方面,【???这句话没看懂】

So, as Apollo drew to a close, they pointed at the DynoSoar program as the model, and said, “This is the shuttle we want.”

因此,当Apollo计划接近尾声时,他们将DynoSoar计划作为模型,并说:“这就是我们想要的航天飞机。”

But, then the committees got a hold of it. Simply getting people to and from space wasn’t enough. NASA wanted a way to get astronauts into space, but NASA had a limited budget. The Air Force wanted to get satellites to space and they had a much larger budget, so the Air Force got brought into the discussion. The Air Force, however, wanted cargo, not people. Other groups like the NRO (National Reconnaissance Office) and the like said they needed to put up satellites the size of school buses for doing satellite reconnaisance, i.e. spy satellites.

但是,然后委员会掌握了它。仅仅让人们进出太空还远远不够。 NASA想要一种将宇航员送入太空的方法,但是NASA的预算有限。空军希望将卫星送上太空,而且预算要大得多,因此空军参与了讨论。但是,空军要的是货物,而不是人员。 NRO(国家侦察局)等其他组织则表示,他们需要安装像校车大小的卫星来进行卫星侦察,即间谍卫星。

That means that the small, manageable X-20 sized shuttle was tossed out in favor of the giant cargo space of what came to be the Space Shuttle. But, more cargo space means more “space-plane” to house it. That raises the mass of the shuttle. More mass means bigger wings to land it, and more powerful rockets to lift it.

大家青睐于更大的货运空间,这意味着小型,易于管理的X-20航天飞机被抛弃,这导致了航天飞机的出现。但是,更多的载货空间意味着需要更多的“空间平面”来容纳它。这增加了航天飞机的重量。更大的质量意味着需要更大的机翼将其放稳,需要更强大的火箭将其提升。

The whole thing became an almost comical cycle. With the shuttle needing that much lift, the engines became so expensive and time consuming to build that even Lockheed said they could no longer be expendable, and had to be re-used to make the shuttle even vaguely affordable. That meant the engines had to be recovered, which meant they had to be part of the shuttle. With engines mounted in the tail of the shuttle, it couldn’t sit on top of the stack any more.

整个过程几乎变成了滑稽的循环。由于航天飞机需要这么大的升力,因此发动机的制造变得如此昂贵和费时,甚至洛克希德公司也表示它们已经耗不起了,必须让航天飞机可以重新利用好让它的价格降下来。这意味着必须对引擎进行回收,这意味着它们必须成为航天飞机的一部分(而不是仅仅是火箭的一部分)。由于发动机安装在航天飞机的尾部,因此它不再位于组装火箭的顶部。

And that’s vitally important. In the event of an accident, a capsule mounted at the top of a rocket stack has a chance to escape. When you’re strapped side-by-side to a giant bomb, as Challenger showed, there’s nowhere to go when something goes wrong.

这至关重要。万一发生事故,安装在火箭顶部的逃逸仓就有可能逃脱。但如果你还绑着一颗巨大的炸弹时,就像挑战者号那样的话,神仙也救不了你了。

Worse, strapping to the side of the stack (off-axis for those who are picky about such terms) leads to all kinds of other compromises. The piping for fuel must now go directly through the heat shields that cover the bottom of the shuttle, creating headaches in just how to ensure that the covering is safe for a 3500 degree re-entry.

更糟糕的是,捆扎在火箭的侧面(偏离轴心)会导致各种其他折种。现在,燃料管道必须直接穿过覆盖航天飞机底部的隔热板,这在如何确保覆盖层可安全地重新进入3500度方面造成麻烦。

The shuttle is now in the path of any debris breaking away from the fuel tank. (This was opposite what you saw on the Saturn V launches, where great sheets of ice would peel away from the cryogenic tanks on the rocket, falling harmlessly along the surface of the rocket.) This meant the fuel tank had to have extreme insulation to prevent ice from forming, because the ice would now crash into the shuttle, cutting through its fragile tiles that protected it from reentry. So, thick foam insulation was placed over the entire tank, adding more weight, and more headaches, because the slightest flaw in how the foam bonded to the surface meant chunks of foam peeling off the tank and striking the shuttle. This was what would lead to the destruction of Columbia.

航天飞机的油箱上的任何碎片都可能会脱落, (这与您在土星V发射中看到的相反,土星V发射时大量的冰块会从火箭的低温油箱上剥落,并沿着火箭表面无害地掉落。)这意味着油箱必须具有极高的绝缘性防止结冰,因为冰会刺入如航天飞机,毁掉脆弱的,用于再入大气的保护罩。因此,厚厚的泡沫隔热材料会被放置在整个储罐上,增加了重量,也增加了工程师的头痛程度,因为泡沫与表面的粘合方式上的最轻微缺陷可能意味着大量泡沫从储罐上剥落并撞击航天飞机。这就是导致哥伦比亚被毁的原因。

The main weight at launch is in the expendable fuel tank, carrying nearly 1.6 million pounds of hydrogen and oxygen, 20 times the mass of the shuttle itself. If you think of the engines on the shuttle as lifting that weight, then imagine that the center of gravity is nearly 20 feet off-line from the lift of the engines that are lifting it. That meant the shuttle, and the fuel tank, had to have reinforced structures to support all that off-axis thrust. And that meant even more weight to be lifted to orbit in the shuttle, and nearly to orbit in the fuel tank.

发射时的主要重量在消耗性的燃料箱中,该燃料箱携带近160万磅的氢气和氧气,是航天飞机本身质量的20倍。如果您认为航天飞机上的发动机可以推动这些重量,那么可以想象一下,重心与正在举升发动机的举升力相距近20英尺。这意味着航天飞机和燃油箱必须具有加固的结构,以支撑所有偏轴推力。这意味着需要将更多的重量举升到航天飞机的轨道上,而几乎要举升到油箱的轨道上。

The numbers got so bad, the only way to solve the problem was to strap on giant, solid-fuel rocket boosters to get this travesty off the pad. But solid fuel has a problem. It has exactly two settings, “Not Lit” and “Full Throttle”. Now, to be technical, the SRBs had fuel mixes pre-loaded that created a thrust profile to match the flight events like Max-Q, and other adjustments, however, this was not an exact science and usually there were 2–3 second windows where the thrust profile would change, and the shuttle main engines would have to compensate.

这个数字很不好看,解决问题的唯一方法是绑上巨大的固体燃料火箭助推器,以消除这种麻烦。但是固体燃料有一个问题。它有两个设置,“不点亮”和“全油门”。【???其中一个应该是说固体燃料点燃后就不能停了】现在,从技术上讲,SRB已预装了混合燃料,从而创建了推力曲线以匹配Max-Q等飞行事件以及其他调整,但是,这并不是精确的方法,通常有2-3秒的窗口期让推力曲线将发生变化,航天飞机的主发动机必须进行补偿。

Additionally, the SRBs were prone to “thrust oscillation” (think bouncing up and down like a pogo stick) events, vibration along the direction of travel, which tended to shake everything violently. Again, these were also there to lift the 1.6M pounds (800 tons) of fuel in the external tank. These boosters were also mounted off-axis, meaning they were also lifting on a lever arm 20 feet off-axis from the center of mass.

此外,SRB容易发生“推力震荡”(像弹簧娃娃一样上下弹跳)事件,沿行进方向的振动,这往往会剧烈震动所有物体。同样,它们也可以在外部油箱中提起160万磅(800吨)的燃料。这些助力器也离轴安装,这意味着它们将会从从离质量中心20英尺的轴上抬升。

This meant more reinforcement and more weight. In the end, the STS (Space Transit System) was burning about 3.8 million pounds of fuel (1.6M in the external tank, plus 1.1 million in each booster) to lift the 200,000 pound shuttle into orbit. That’s a 5% fuel to weight ratio, which is actually rather good, but remember, the shuttle wasn’t actually the cargo.

这意味着更多的加固和更多的重量。最终,STS(太空运输系统)燃烧了约380万磅的燃料(外部油箱为160万磅,每个助推器另加110万磅),以将20万磅的航天飞机升入轨道。那是5%的燃料重量比,这实际上是相当不错的,但是请记住,航天飞机实际上并不是货物。

The cargo was whatever satellite or bit of the space station they were trying to launch into orbit.

货物是他们试图发射进入轨道的任何卫星或空间站的一部分。

The maximum weight that a shuttle could take to LEO (low-earth orbit) was 65,000 pounds. So, the shuttle burned 3,800,000 pounds of fuel to get a maximum of 65,000 pounds to orbit. The average cost per flight on a shuttle was about $450,000,000 per mission. That’s a cost per pound of $6923 and change to low earth orbit, and the shuttle almost never flew at maximum cargo weight.

航天飞机可以携带到LEO(低地球轨道)的最大重量为65,000磅。因此,航天飞机燃烧了3,800,000磅燃料,最多可行驶65,000磅。航天飞机每次飞行的平均费用约为每次任务4.5亿美元。那是每磅6923美元的成本,然后转换为低地球轨道,航天飞机几乎从未以最大货物重量飞过。

To put it in perspective, while the Saturn V was more expensive (about $1.16B per flight in modern dollars) it could carry 261,000 pounds of cargo to orbit, a price per pound of about $4445. And they were throwing the entire rocket away on each flight.

从另一个角度来看,虽然土星V较贵(按现代美元计算,每次飞行约$ 1.16B),但它可以运载261,000磅的货物进入轨道,每磅的价格约$ 4445。而且他们在每次飞行中都将整个火箭扔掉了。

To put that into perspective, the entire ISS weighs about 440 tons right now. The Saturn V could have lofted that in four flights, and almost could do it in three. (130.5 tons per flight.) The Space Shuttle had 36 designated ISS missions to loft parts of the station, and several parts were added by Russia, Japan, and even the ESA without the help of NASA. In fact, the current mass includes several portions brought up by SpaceX and Orbital as well.

从整体上看,整个国际空间站目前的重量约为440吨。土星五号只需要四次飞行就能把所有必要的组件带上去,甚至有可能只要3次。 (每次飞行130.5吨。)航天飞机有36次指定的ISS任务把所有组件送上去,而俄罗斯,日本甚至ESA在没有NASA的帮助下又增加了几个部分。实际上,空间当前质量包括SpaceX和Orbital带来的几个部分。

All this doesn’t even mention the fragility of the tile system on the shuttle. Every mission required the inspection of every tile, and the replacement of hundreds if not thousands that were damaged on each flight.

所有这些甚至都没有提到航天飞机上组件系统的脆弱性。每次任务都需要检查每个组件,并更换数百个(也有可能是数千个)在每次飞行中损坏的组件。

The Main Engines had to be totally refurbished after every flight, the entire turbopump assembly removed, and rebuilt. The idea that was sold….

每次飞行后必须对主机进行彻底的翻新,然后拆下整个涡轮泵组件,然后进行重建。这种使用方法

…was nothing at all like what was actually delivered.

……根本不像交货时说的那样。

When added to the Shuttle’s dismal safety record, the broken promises of re-usability — Congress was promised it would fly, “once a week with only minor refurbishment between flights” — there’s no choice about the worst rocket design ever put into use, and that’s the Space Shuttle.

在航天飞机糟糕的安全记录中,还要加一个虚假的可重复使用性的诺言–国会曾承诺它将“一周飞行一次,每次飞行之间仅进行很小的翻新”,要问最糟糕的火箭设计,那别无选择,就是航天飞机。

(Edited to correct the term “Pogo” for SRBs — which is reserved for on-axis oscillations in liquid fueled rockets — to the correct term, which is “Thrust Oscillation”.)

Footnotes

[1] Jeffrey Naujok’s post in Lost Comments

[2] Jeffrey Naujok’s post in Lost Comments

【后记:NASA在2011年正式取消了航天飞机项目,目前一直靠着俄罗斯联盟号飞船送卫星上天。总之,航天飞机太烧钱了。最后放上NASA制作的航天飞机的标志。】

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