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SpaceX and Boeing Still Need a Parachute That Always Works
- shmerl 7y ago> 600 mph Probably better to use km/h, especially for space related coverage.
- kawfey 7y agoAmericans don't have an intuitive sense of metric units, and Wired is based in the US and has mostly US readership. I agree with you, and I'll bet the editor also agrees, but they'd probably get FAR more comments to use imperial units because 'merica, if metric was used instead.
- ptaipale 7y agoWhen discussing speed of an object that is landing, m/s might in fact be even better for most of the world.
- shmerl 7y agoThat's one of the ways to develop intuitive sense - start using it everywhere. It will never develop if it's not used. Besides, officially US was supposed to switch to metric system anyway, so formally there is nothing wrong with using it and no one should be complaining. Except it takes ages and almost not moving anywhere due to complete apathy from the government about it.
- catalogia 7y ago> Americans don't have an intuitive sense of metric units I don't really believe that. American public schools have been teaching the metric system to middle schoolers for a few decades now. Every American I talk to understands the metric system. In some cases, particularly units of volume, they understand the metric system better than the imperial units (liters are easy, but I can never keep quarts/pints/cups/floz/etc straight in my head.) Coca Cola sells sugar water to Americans in liter-oriented packaging (.5, 1, an 2 liter bottles are ubiquitous), and Americans certainly don't balk at that. They drink it up.
- shmerl 7y agoVolume effort went well indeed. What's still lagging behind especially are temperature, distance and speed units. Lot's of people are still not comfortable when you are trying to use metric for them. Which probably only highlights that there should be a stronger push to use them. Also, 24H time system is something people often don't get, and only know about it as "military time", due to army actually using it.
- catalogia 7y agoI think temperature is easily the most alien to Americans. Metric distances probably aren't quite as well understood as metric volumes, but I'd wager that knowledge only trails by a little. The rough equivalence between a yard and a meter is widely know by Americans, as is the rough equivalence between 100km/hr and 60mph (helpfully, American speedometers all provide this education.)
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- jcranmer 7y agoThe distances you cite are pretty much the only ones (well, 2.54cm = 1 in as well) that are likely to be well-known. Yards are just not a heavily-used unit, people prefer 10s or 100s of feet instead of using yards. So when you go from tens to hundreds of meters, there is going to be no intuition about what kind of distance that actually is, and you have to mental math your way to familiar units of 100s of feet or quarter/half miles.
- shmerl 7y agoThe only way to gain intuition is to use units straight, without doing mental translation.
- catalogia 7y agoMeters to feet is easy, it's roughly just x3. Yards may not be common (yards are certainly common in sports, and sports are very popular), but three feet to the yard is definitely commonly known. Centimeters might be harder, but in my experience Americans suck at estimating inches too, one American's "half an inch away" is another American's "two inches away." And the average American off the street would be hopeless if asked how many feet are in a mile. They'd actually have a better chance of giving you a kilometer->feet conversion than miles->feet. At least, I certainly would (without looking it up: 1 kilometer = 1000 meters ~= 1000 yards = 3000 feet, +10% fudge, approximately 3300 feet to the kilometer.) Anyway, my point in all of this is that if a pop-sci publication like Wired uses units like kilometers, it is unlikely that their American readers will be confused. They'll probably walk away from such an article with a casual understanding of the subject that is reasonably close to the casual understanding they'd have if the article used miles instead.
- arijun 7y agoIt's too bad NASA didn't let SpaceX test propulsive landing with the cargo Dragons. Without that, SpaceX scrapped the feature from the Dragon program as a whole. It seems like they might have been able to get more reliability with that than the parachutes. And even if not, if I was sitting in a capsule that had a history of parachute failures, I'd feel a whole lot safer if there was a backup propulsive system ready to kick in in the event of a chute failure.
- mzkply 7y agoThey would still have had to work on parachutes because a Pad Abort uses up all the propellant... leading to a parachute landing just off the beach at the Cape.
- apendleton 7y agoThey didn't scrap it exactly, they just relegated its function to use as an emergency propulsive abort system. But the Dragon 2 still has the super dracos... and one of them exploded, causing the loss of a test vehicle, a few months ago, which has resulted in timeline setbacks to the program. It doesn't seem like reliability has been a walk in the park there either.
- waiseristy 7y agoThe super draco didn't explode fyi, it was the fueling system.
- wolfram74 7y agoAn interesting distinction, like saying "the engine didn't explode, the gas tank did" but one wouldn't be there except for the other. I suppose for properly fixing the problem it's important to say one vs the other, but in general conversation it could come off as a pedantic?
- waiseristy 7y agoWell, yes. Pedantic as it may be, the fueling systems seem to be a recurring theme for SpaceX, not their motors. Remember Amos-6?
- xigency 7y agoHow is the problem and solution different than the parachutes used in early NASA programs like Mercury? > Since the design of Boeing’s parachute system is so similar to NASA’s, the company had to perform fewer tests to demonstrate the system’s safety compared to SpaceX. This doesn't seem like a good habit for Boeing.
- GhettoMaestro 7y ago> This doesn't seem like a good habit for Boeing. While I like to bang on Boeing for being fucking dumb about 737MAX, the habit of copying an existing well-tested, approved design is something that should NOT be discouraged. Re-use of existing validated solutions / components leads to faster development cycles and increased agility (financially) . This is achieved by making more critical components COTS (Commercial Off The Shelf - not one-off / custom) and re-usable as self-contained "modules" or "packages". Reinventing the wheel for reinventing the wheel's sake is in most cases not a good use of resources. That said, if the original design has issues, my above commentary is invalidated somewhat - you need to modify the design to fix the root cause, which should trigger a fresh round of validation and testing at the original specification levels or greater. And of course, you should always do fully integrated tests, even if all of the components were previously validated and approved. You pretty much always find stuff (maybe only in solution-integrated combination) - I believe that's what happened in this case.
- pizzaparty2 7y agoUsing old tech is why Boeing lost space though.
- GhettoMaestro 7y ago"Lost" space? I'm not following you. Unless you're referring to how up-start SpaceX has dominated the launch industry in the past 5 to 10 years?
- bendbro 7y agoI don't think he means existing designs shouldn't be reused. I think he means that you shouldn't lessen testing because you are using an existing designs. Boeing reused the 737 design to produce the 737 Max; however, because it was a reused design, Boeing did not go through the same certification process or testing that would have been done for a new airplane. Skipping testing because you have a reused design is the bad habit he is referring to.
- diego 7y agoIt sounds like the old-style parachute is not the best solution for this problem, but I'm sure they must have come up with other ideas and ruled them out. Why not hundreds of small parachutes? Why not wings or rotors to stabilize it? I'm curious to know.
- SliderUp 7y agoAnything non-fabric would weigh too much. Many smaller parachutes means many more lines, which would weigh too much. The rocket equation is cruel.
- 24gttghh 7y agoSmaller parachutes would be larger surface area compared to one large chute also, right? More weight there.
- jccooper 7y agoParachutes were supposed to be easy because they have plenty of heritage and other users. And in spite of the problems they likely still are easier. Any other system would need even more testing.
- Robotbeat 7y agoInterestingly, SpaceX (Dragon), Boeing (Starliner), and NASA/Lockheed (Orion) all use the same supplier/subcontractor for parachutes: Airborne Systems. Parachutes are hard. They're super complicated. They'll figure it out, but this will always be tough.
- namirez 7y ago> Parachutes are hard. I'm surprised to hear this. I've not heard much about parachute failures in Soyuz landings, except Soyus-1 in the 60's. Nasa had a good track record with parachutes too before they started using the space shuttle. Are there technical challenges unique to SpaceX or Boeing that other systems didn't have to deal with?
- Robotbeat 7y agoSoyuz has a reserve parachute. Also, because Soyuz only has one, large primary chute, you're less likely (by a factor of 3 or 4) to see any failures. And a reliability of 142:143 is not terribly high for a safety-critical system. No US orbital crew fatalities have ever occurred due to parachute failure, but parachute failure has occurred on at least one of the Apollo missions (Apollo 15). One parachute failure out of 61 parachutes for the US[0] versus one (or two, counting the reserve) parachute failures out of 143 (144) parachutes for Russia/USSR. The statistics here are effectively indistinguishible in any meaningful measure. The challenge is these are new, pre-operational crewed spaceflight systems being developed from the beginning. New systems ALWAYS have a higher rate of failure for complex things like this, and also because there are not yet actually crew on board, there's a little bit lower level of mission assurance (which I would argue is optimal!). Nothing in particular special about SpaceX or Boeing. And in many ways, we got lucky that there weren't more parachute-related fatalities. We understand the dynamics significantly better now than in the past. [0](1 parachute on each Mercury and Gemini mission, 3 parachutes on each Apollo capsule)
- avmich 7y ago> And a reliability of 142:143 is not terribly high for a safety-critical system. That's a 50+ years ago flight on a system which was being debugged - unfortunately, too hastily. Parachutes subsystem underwent major rework after that catastrophe, and the follow-up flight history attests to it. One can call it "142:143" only as a first approximation.
- Flockintosh 7y agoSpaceX's and Boeing's crew capsules just passed crucial tests. Boeing’s Starliner completed a pad abort test, showing it could ferry astronauts away from a launch-site problem by reaching 650 mph in just 5 seconds. And SpaceX successfully tested Crew Dragon's parachutes 13 consecutive times. http://www.astronomy.com/news/2019/11/spacex-and-boeing-complete-crucial-tests-for-their-crew-capsules http://www.astronomy.com/news/2019/11/spacex-and-boeing-comp...
- lightedman 7y agoYou simply cannot make a parachute that always works. My pal that works at SkyDive Perris has seen plenty of perfectly-packed parachutes fall prey to an errant gust of wind turning the chute inside-out mid-deployment and making it useless, requiring immediate deployment of the backup. Now imagine this happening under supersonic conditions. Recovery would be almost impossible. This is why skydivers wear multiple chutes.
- zlsa 7y agoThe solution common to Boeing and SpaceX is the same: they have three (Boeing) or four (SpaceX) separate parachutes, each with their own drogue chutes, and they both can handle a single deployment failure without endangering the crew.
- ceejayoz 7y ago> Now imagine this happening under supersonic conditions. Seems like even a big gust wouldn't make much difference at supersonic speeds in thin atmosphere.
- colebowl 7y agoThis may just be conjecture but it's always seemed like they are solving the wrong problem. Why aren't they looking for alternatives to parachutes which to me seem like an archaic way of doing things. In saying that, the number of different maneuvers required in landing the space shuttle definitely shows how hard this problem is.
- zlsa 7y agoSpaceX originally planned to develop a [propulsive landing system](https://youtu.be/Cf_-g3UWQ04?t=90 https://youtu.be/Cf_-g3UWQ04?t=90), but this was dropped due to several reasons: * The additional risks of a relatively untested system * Starship development had begun, which would make Dragon obsolete Propulsive landing of Dragon was therefore scrapped (and [Red Dragon](https://en.wikipedia.org/wiki/SpaceX_Red_Dragon https://en.wikipedia.org/wiki/SpaceX_Red_Dragon), a plan to send uncrewed Dragons to the surface of Mars, along with it.)
- DuskStar 7y agoDon't forget the biggest reason - the LES system used the same fuel as the propulsive landing system, and they only carried enough for one of the two. Which meant that landings after using the LES would require a parachute, and if you're carrying a parachute with you anyways why not just use it all the time?
- cameldrv 7y agoIt seems to me that the parachute(s) you need for LES wouldn't need to be as complex and capable as landing parachutes. The LES parachute(s) will be firing at quite low speeds, so they don't need to be too strong. The LES parachute(s) also don't need to be nearly as reliable or give nearly as soft a landing. Ejection seats in combat aircraft show the same tradeoff -- it's considered acceptable to have ejection seats that fail sometimes and sometimes cause a landing injury. Hopefully you never have to use it, and so even if it fails or injures you say 10% of the time, it's much better than certain death in a pad explosion or similar.
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- stanmancan 7y agoIt’s a strange thing. I never expected parachutes to be the hard part when sending people to space. Any idea why this is causing such a headache?
- indue 7y agoApparently the phrase should be "It's not parachute science" since that appears to be more difficult than "rocket science."
- JaggedJax 7y ago"Fly safe"
- tropo 7y agoSupersonic parachutes are terrible. Notice that supersonic aircraft air intakes involve ramps (F-15, Concorde, XB-70, F-14), shock cones (SR-71, MiG-21), or diverterless supersonic inlet (F-35, FC-1 Xiaolong). Simple round openings, without a central spike, do not work well at all. It's bad news for parachute design before even thinking about the problems of parachute lines and the need to withstand shock waves as the geometry rapidly changes while unfolding. The right solution is probably the ballute. SpaceX, Rocket Lab, Armadillo Aerospace, and Copenhagen Suborbitals have all been investigating ballutes in recent years. https://en.wikipedia.org/wiki/Ballute https://en.wikipedia.org/wiki/Ballute