# Why did Rocket Ship Design Change? **URL:** \ **Category:** Factual Questions\ **Created:** [October 24, 2007, 12:16pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806 "2007-10-24T12:16:44Z")\ **Posts on this page:** 15\ **Page:** 3
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [October 24, 2007, 7:45pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/41 "2007-10-24T19:45:15Z")
… you know, an M1A1 Abrams isn’t anywhere near as sleek looking as those tanks in “Things to Come” or Popular Mechanics illustrations from the Thirties… ---
**Author:** ![ignis\_glaciesque](https://avatars.discourse-cdn.com/v4/letter/i/5f8ce5/32.png) [@ignis\_glaciesque](https://boards.straightdope.com/u/ignis_glaciesque)\ **Post date:** [October 24, 2007, 9:13pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/42 "2007-10-24T21:13:15Z")
Well, I’m not entirely sure about this, but I know that the reason the Shuttle wasn’t made especially streamlined is for shockwave deflection — a blunt nose will give a much shallower shock cone than a pointy one. If the Shuttle had a pointy nose, the shockwaves from travelling through the air at some ungodly multiple of Mach would wreak untold havoc on the aerodynamic control surfaces of the wings and tailfin. Also, having the shockwave as sort of a buffer between the Shuttle’s skin and the rest of the atmosphere gives the added bonus of a little less thermal heating on re-entry. At least, this is what I heard; I am not an aerospace engineer. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 24, 2007, 9:22pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/43 "2007-10-24T21:22:25Z")
> [@](#): > > … you know, an M1A1 Abrams isn’t anywhere near as sleek looking as those tanks in “Things to Come” or Popular Mechanics illustrations from the Thirties… But those models and illustrations weren’t done by tank manufacturers predicting and promising the future of weaponry – they were done by illustrators who wanted something that looked futuristic and different. The suggestion of some here is that the rocket engineers were doing a bit of both. ---
**Author:** ![buckgully](https://avatars.discourse-cdn.com/v4/letter/b/eb9ed0/32.png) [@buckgully](https://boards.straightdope.com/u/buckgully)\ **Post date:** [October 24, 2007, 11:34pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/44 "2007-10-24T23:34:53Z")
While hunting around for some cites to make a point here, I found this article that A) pretty much covers the OP, and B) completely blew away the point I was going to make. [http://www.astronautix.com/lvfam/vonbraun.htm](http://www.astronautix.com/lvfam/vonbraun.htm) It seems that it comes down to the streamlined designs being drawn using Von Braun’s specs by artists for public consumption, and the designs were obsolete even before the last iterations went out. They were all based on assumptions that Von Braun made in 1948 and were updated more for their visual look than real-world engineering advances. It’s pretty interesting. To be honest, I’d never looked at how and when these images were presented, I’d always assumed that the streamlined designs were either purely artistic creations, or from a time before anyone was really sure of what a rocket beyond the V-2 would really look like. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 24, 2007, 11:50pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/45 "2007-10-24T23:50:46Z")
Excellent work, **buckgully**! ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [October 24, 2007, 11:55pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/46 "2007-10-24T23:55:26Z")
[QUOTE=Omphaloskeptic] I doubt you’ll find a single explanation for all of these protrusions any more detailed than “engineering tradeoffs,” and you’d probably have to track down all of the engineers to get all of those answers. What you’re calling the “ribbed panels” on the Mercury and Gemini capsules (if you mean the corrugated black shingles) are actually heat-radiating fins for reentry; Apollo used a different design. The vertical ribbing along the sides of the rocket I would guess is for strength. This isn’t needed so much along most of the rocket’s length, since the individual stages can have interior bracing (much of it provided by the tanks and plumbing); but the stage joints don’t have any of this internal structure and need all of the strength in a thin ring. I see various protrusions on the Apollo payload shroud that are probably parts of the hinges. The flat front on Gemini may have been required for the docking experiments. (Apollo had a flat front too, for docking with the LEM; they were both covered by aerodynamic shells during liftoff.) These are all little compromises. I doubt if someone doing a proof-of-concept design would worry about details like exactly how stiff the interstage ring needs to be. It’s not until it turns into a battle of ounces that you have to break out the handbooks and figure all of these little trade-offs out. [/QUOTE] I think we have the winner. Rocket design is the art of compromise and optimization. If you see an exposed hinge, it’s probably exposed because some engineer did the math and determined that the small amount of additional drag was a better tradeoff than adding the weight of a hinge shroud or increasing the diameter of the rocket. Ribbed sections add a lot of strength with no addition of weight. Or perhaps they are ribbed to allow for expansion and contraction due to the cryogenic fuel. Or perhaps some of the external bumps are valves and various fluid lines and such put on the outside of the rocket because putting them on the inside would require more heavy insulation to protect them from the cold of the fuel, and it was worth trading off drag for weight. In less optimal designs, you can often declare ‘good enough’ and move on. A rocket isn’t like that. There’s a reason for everything. Point to any little bump or wrinkle on a rocket, and you can probably find a sheaf of documentation justifying it, sometimes with a reason you would never have imagined. There’s no ‘one big difference’ in how rockets are designed today. Some of the stuff you see could also be for boundary layer control, control of supersonic shockwaves, and other aerodynamic tricks that we learned about from hard experience, wind tunnel testing, and later on, computational fluid dynamics and the like. Tools, techniques, and observations that may not have been available to Von Braun and his ilk. Sometimes a change in one aspect of the rocket can have dramatic ripple effects on the design elsewhere. The addition of computer guidance and steerable engines means the elimination of fins, which means the elimination of support structures for fins and their aerodynamic loads, which changes the shape of the lower stage, which effects the shape of the upper stages, etc. Computer guidance means the rocket can be dynamically unstable, which further changes the shape. Airplanes undergo the same kinds of transitions when new technology changes a fundamental characteristic. ---
**Author:** ![Walloon](https://avatars.discourse-cdn.com/v4/letter/w/fbc32d/32.png) [@Walloon](https://boards.straightdope.com/u/Walloon)\ **Post date:** [October 25, 2007, 3:10am UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/47 "2007-10-25T03:10:15Z")
This thread is an example of SDMB at its collaborative best. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [October 25, 2007, 4:26am UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/48 "2007-10-25T04:26:44Z")
[QUOTE=CalMeacham] But those models and illustrations weren’t done by tank manufacturers predicting and promising the future of weaponry – they were done by illustrators who wanted something that looked futuristic and different. The suggestion of some here is that the rocket engineers were doing a bit of both. [/QUOTE] From the beginning people kept trying to tell you that your assumptions were wrong. As they proved to be. Looking good really was the driving factor even though you kept disclaiming the possibility. This is not anything new or different. Many GQ threads are based on people making assumptions about answers and then not being able to understand why they’re wrong. They are wrong because they’re assumptions are wrong. Some people come to accept that, as you did, and some refuse to do so which makes for the banging-heads-against-walls threads. Watch and see how many threads you come upon over the next few days that follow this syndrome. I think you’ll be surprised at how common they are. ---
**Author:** ![OtakuLoki](https://avatars.discourse-cdn.com/v4/letter/o/ac8455/32.png) [@OtakuLoki](https://boards.straightdope.com/u/OtakuLoki)\ **Post date:** [October 25, 2007, 6:58am UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/49 "2007-10-25T06:58:27Z")
**CalMeacham** , I think one factor to consider is that streamlining is not always energy efficient. [Laminar flow](http://en.wikipedia.org/wiki/Laminar_flow) of fluids actually involves frictional losses along each laminar layer as it moves against each other layer. Going for a turbulent flow model, espeicially at the much higer speeds that rockets operate in, compared to aircraft, is going to reduce frictional drag. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 25, 2007, 12:36pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/50 "2007-10-25T12:36:04Z")
> [@](#): > > From the beginning people kept trying to tell you that your assumptions were wrong. I don’t think you’re reading them carefully enough – too many of the early replies seem to be making the assumption that I was asking why the rocklets we came up with didn;t look like the ones in pulp illustrations. wasn’t asking that, and had to point it out several times. My assumptions weren’t wrong – I was asking why the designs being presented by the rocket engineers (not illustrators or even science fiction writers, but the guys who were spending all their time on this, doing it for a living, and who had already been not mrely designing but builduing and flying rockets for up to twenty years earlier) were so dramatically different from the actual working designs used in the 1960s. And you can see it extremely clearly if you look at the Colliers magazine illustrations, or the Duisney shows of the 1950s, both of which I referred to, and were based directly ion the work of von Braun and his collaborators. It’s not merely streamlining per se, but also the overall look that accompanies that streeamlining. And most of the replies, whether they addressed my question correctly or not were guesses – yours included. I got contradictory suggestions regarding the need for streamlining (and the original V2 designs , built by members of the team, _were_ streamlined, so it wasn’t merely done by look, but was an implemented factor). It was suggested that you couldn’t streamline a multistage rocket, but that;'s precisely what they did do. I have to thank **buckgully** for his excellent link (although I’d like to know more abnout where his source came by a lot of that info), and **omphaloskeptic** and **Sam** are correct about engineering tradeoffs, but I never did say that there was any one factor explaining everything about all the blips and bulges on the outside of the rocket. But there ARE two that would explain their absence – if 1.) Streamiling WAS of overriding importance (in which case the engineering tradeoff would have impelled the designers to build all those hinges, heat sinks, and other features inside, regardless of greater cost elsewhere) or 2.) It was being done to “sell” the idea to NASA and Congress and the public (I find it interesting that von Braun and company were scamming the Nazis, too, by workling on the A-9 that they were forbidden to do by remaming it the A-4B, as **buckgully** ’ss link states.) Either or both of those factors (both, apparently) can explain why the designs looked the way they duid in the 1950s but ended up being built as they were in the 1960s. I’m extremely curious about the design details of the capsules that **omphaloskeptic** refers to so offhandedly, and that I’ve never heard of. It’s bothered me why the Mercury and Gemini capsules had that weird ribbing on them, that he says was a heat sink. I’ve never heard that before, It doesn’t look like any heat sink I’ve seen (but I could see why it would be, in a compromise between efficiency of heat transfer against excessive drag), and would like to know more. How did they do away with that for the heavier Apollo capsule, which looks so streamlined? And it’s also bugged me that the Mercury and Gemini capsules had such flat and “busy” nonaerodynamic fronts, while the Apollo capsule WAS rounded as you’d expect (and as most missile fronts were – look at the front of the Titan without the Gemini capsule on it, or the Atlas or Redstone without the Mercury capsule. Or the Agena that was sent up to rendezvous with Gem,i ni. “Aerodynamic”-style streamlined noses weren’ty just a naive expectation of the uninformed public, they were the norm outside of the earliest manned spacecraft). So, no, I don;'t believe at all that I was ig noring the persistent suggestions of people. I answered criticisms that were inappropriate because they hadn’t properly read the OP, and I gave my reasons for doubting unsupported suggestions until better-supported and better reasoned posts came along. And I think **Walloon** ’s comment is dead on. Thanks to all who contributed. ---
**Author:** ![Omphaloskeptic](https://avatars.discourse-cdn.com/v4/letter/o/bcef8e/32.png) [@Omphaloskeptic](https://boards.straightdope.com/u/Omphaloskeptic)\ **Post date:** [October 25, 2007, 7:17pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/51 "2007-10-25T19:17:12Z")
I think **Exapno** was being kind of harsh. I think it is a good question; I just don’t think it has a single answer. **buckgully** ’s link says that the pictures you saw were just outdated versions of pictures of earlier designs, which nicely explains why the pictures all looked the same but doesn’t explain the major changes in shape for the later designs. I’d guess the gross shape changes are (as **mks** says) due to better understanding and design for supersonic flight; I don’t really understand the supersonic regime, though. My previous post was just pointing out that every little bump has its own story, trading off aerodynamics for something else for a net gain. > [@](#): > > _I’m extremely curious about the design details of the capsules that **omphaloskeptic** refers to so offhandedly, and that I’ve never heard of._ It’s pretty hard to find good online technical documentation on the early space missions. The first clue is of course that they are a corrugated, non-glossy black that you don’t see anywhere else on the rocket–it just looks like a heat sink. [Here](http://www.apollosaturn.com/geminiNR/sec12.htm)’s the best description I can find; it’s quite a nice summary of the sort of extra engineering problems that come with manned spaceflight. Page down to the section “GEMINI THERMAL RADIATION CONTROL COATINGS” for a discussion of the requirements for thermal control and the various layers used. You can also [Google with “Rene-41,”](http://www.google.com/search?hl=en&safe=off&q=%22rene+41%22+shingle+gemini&btnG=Search) the high-temperature nickel alloy used. > [@](#): > > _How did they do away with that for the heavier Apollo capsule, which looks so streamlined?_ Part of the answer is “heavier”–i.e., another engineering trade-off; and part is technological advances. Apparently Apollo used [ablative heat shielding](http://history.nasa.gov/SP-4205/ch4-2.html) for the conical upper section as well as the bottom disc. Read the link for some of the tradeoffs (higher weight; but probably able to shed more heat, and also providing some radiation shielding to the crew). > [@](#): > > _And it’s also bugged me that the Mercury and Gemini capsules had such flat and “busy” nonaerodynamic fronts, while the Apollo capsule WAS rounded as you’d expect (and as most missile fronts were – look at the front of the Titan without the Gemini capsule on it, or the Atlas or Redstone without the Mercury capsule…_ Here I think you’re comparing the wrong pictures. The Mercury, Gemini, and Apollo capsules all had relatively flat fronts; these were all covered with some sort of aerodynamic and protective shell (and sometimes a launch escape tower) for launch. (Here’s [Gemini 7 from Gemini 6](http://dayton.hq.nasa.gov/IMAGES/LARGE/GPN-2000-001049.jpg) and here’s [Apollo 16 from the LEM](http://dayton.hq.nasa.gov/IMAGES/LARGE/GPN-2002-000069.jpg).) But of course the aerodynamic front is only needed for launch; after that there’s no reason to keep the top side aerodynamic. The strange cone-cylinder shape of Mercury and the similar Gemini design appears to be mostly [a tradeoff](http://www.hq.nasa.gov/pao/History/SP-4201/ch4-5.htm) between reentry stability, afterbody heating, and parachute stowage. Contrasting manned capsules with the payload sections of unmanned missiles I think is another apples-to-oranges comparison. For unmanned missiles, all you see is a lightweight aerodynamic shroud. The payload doesn’t need food or water, doesn’t get tired of the dark, and usually doesn’t have to come back in one piece, so the shroud can be installed over the payload days before launch; all that’s required of the shroud is that it be able to separate itself from the payload without damaging it. There’s a lot of extra engineering in making a large payload, easily accessible up to launch time, easily separable at any point in the launch, and able to withstand reentry. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 25, 2007, 7:24pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/52 "2007-10-25T19:24:54Z")
> [@](#): > > Here I think you’re comparing the wrong pictures. The Mercury, Gemini, and Apollo capsules all had relatively flat fronts; these were all covered with some sort of aerodynamic and protective shell (and sometimes a launch escape tower) for launch. (Here’s Gemini 7 from Gemini 6 and here’s Apollo 16 from the LEM.) But of course the aerodynamic front is only needed for launch; after that there’s no reason to keep the top side aerodynamic. The strange cone-cylinder shape of Mercury and the similar Gemini design appears to be mostly a tradeoff between reentry stability, afterbody heating, and parachute stowage. No – I clearly recall that Mercury capsules had a non-rounded tip at launch, and so , IIRC, did Gemini. Apollo definitely had a rounded cover at launch (and was surmounted by that Emergency Escape Tower construction. My point about the non-manned rockets is that they always had rounded tops. So I don’t think I’m comparing the wrong pictures at all. I built quiite a few models of these ships as a kid – I got to know the tips quite well. Ablative coatings were studied at the Avco Everett lasns where I worked for a time. They had (still have, in fact, in their new home) a picture on the wall comparing the ablation observed vs. the predicted ablation from a re-entry tip. The tip is rounded. I was under the impression that they used such material in all manned flights, but I never checked up on it. Kantrowitz’ work wass early enough for it to be applied to Mercury. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 25, 2007, 7:33pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/53 "2007-10-25T19:33:28Z")
> [@](#): > > Here I think you’re comparing the wrong pictures. The Mercury, Gemini, and Apollo capsules all had relatively flat fronts; these were all covered with some sort of aerodynamic and protective shell (and sometimes a launch escape tower) for launch. (Here’s Gemini 7 from Gemini 6 and here’s Apollo 16 from the LEM.) But of course the aerodynamic front is only needed for launch; after that there’s no reason to keep the top side aerodynamic. The strange cone-cylinder shape of Mercury and the similar Gemini design appears to be mostly a tradeoff between reentry stability, afterbody heating, and parachute stowage. No – I clearly recall that Mercury capsules had a non-rounded tip at launch, and so , IIRC, did Gemini. Apollo definitely had a rounded cover at launch (and was surmounted by that Emergency Escape Tower construction. My point about the non-manned rockets is that they always had rounded tops. So I don’t think I’m comparing the wrong pictures at all. Picture of Gemini Capsule atop Titan – no cap: [http://en.wikipedia.org/wiki/Image:Titan2.jpg](http://en.wikipedia.org/wiki/Image:Titan2.jpg) Mercury Capsule: > **[Project Mercury](https://en.wikipedia.org/wiki/Project_Mercury)** > > Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbit and return him safely, ideally before the Soviet Union. Taken over from the US Air Force by the newly created civilian space agency NASA, it conducted 20 uncrewed developmental flights (some using animals), and six successful flights by astronauts. The program, which took its name from Roman mythology, cost... Apollo Capsule at launch with rounded cap: [http://www-pao.ksc.nasa.gov/kscpao/history/apollo/apollo.htm](http://www-pao.ksc.nasa.gov/kscpao/history/apollo/apollo.htm) I built quiite a few models of these ships as a kid – I got to know the tips quite well. Ablative coatings were studied at the Avco Everett lasns where I worked for a time. They had (still have, in fact, in their new home) a picture on the wall comparing the ablation observed vs. the predicted ablation from a re-entry tip. The tip is rounded. I was under the impression that they used such material in all manned flights, but I never checked up on it. Kantrowitz’ work wass early enough for it to be applied to Mercury. ---
**Author:** ![Omphaloskeptic](https://avatars.discourse-cdn.com/v4/letter/o/bcef8e/32.png) [@Omphaloskeptic](https://boards.straightdope.com/u/Omphaloskeptic)\ **Post date:** [October 25, 2007, 8:27pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/54 "2007-10-25T20:27:39Z")
[QUOTE=CalMeacham] No – I clearly recall that Mercury capsules had a non-rounded tip at launch, and so , IIRC, did Gemini. Apollo definitely had a rounded cover at launch (and was surmounted by that Emergency Escape Tower construction. My point about the non-manned rockets is that they always had rounded tops. So I don’t think I’m comparing the wrong pictures at all. Picture of Gemini Capsule atop Titan – no cap: [http://en.wikipedia.org/wiki/Image:Titan2.jpg](http://en.wikipedia.org/wiki/Image:Titan2.jpg) Mercury Capsule: > **[Project Mercury](https://en.wikipedia.org/wiki/Project_Mercury)** > > Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbit and return him safely, ideally before the Soviet Union. Taken over from the US Air Force by the newly created civilian space agency NASA, it conducted 20 uncrewed developmental flights (some using animals), and six successful flights by astronauts. The program, which took its name from Roman mythology, cost... Apollo Capsule at launch with rounded cap: [http://www-pao.ksc.nasa.gov/kscpao/history/apollo/apollo.htm](http://www-pao.ksc.nasa.gov/kscpao/history/apollo/apollo.htm) [/QUOTE] We might be talking about different things. Your Gemini image doesn’t show the top very well (I can’t find any good top-down views of the capsule in launch configuration), but there’s a white cap there that isn’t there in the picture I linked, which I assumed was some sort of aerodynamic cover. Similarly for Mercury and Apollo the escape tower and cover provide an aerodynamic cover but come off to reveal a flat top. Are you talking about the overall cone-cylinder shape of Mercury or two-cone shape of Gemini versus the smoother blunt single-cone shape for Apollo? > [@](#): > > _They had (still have, in fact, in their new home) a picture on the wall comparing the ablation observed vs. the predicted ablation from a re-entry tip. The tip is rounded. I was under the impression that they used such material in all manned flights…_ What “tip” do you mean? Mercury, Gemini, and Apollo all used ablative shields on the bottom (forward-facing) surface, but apparently (see links in previous post) only Apollo used ablation instead of radiation on the conical afterbody. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [October 25, 2007, 9:22pm UTC](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806/55 "2007-10-25T21:22:45Z")
[QUOTE=Omphaloskeptic] I think **Exapno** was being kind of harsh. [/QUOTE] I wasn’t trying to be harsh. Just that the OP often sees things through different eyes than the rest of us and it’s sometimes frustrating to have what seems to be an obvious point rejected. Since this is so common around here, it’s something OPs should be sensitive to in their own behavior. That helps everyone. [Previous page](https://boards.straightdope.com/t/why-did-rocket-ship-design-change/423806.md?page=2)