36

The Merlin-1D engines are now tuned to use the super cooled fuel and oxidizer. Thus you would be running the engines in an out of normal state, if not using it the same as all other launches with warmer propellant. It would imply different software to handle the different performance levels. Last thing you want to do is run things differently, if you can ...


34

1.) Chairs needed to be custom molded / adjusted for the astronauts. There's stories of people sitting down in bathtubs of foam to create the perfect shape. That is an extra comfort of the Soyuz spacecraft. In NASA spacecraft, the seats were "one size fits all." One of the reasons is that the 'failsafe' modes of Soyuz - launchpad abort, ballistic reentry - ...


29

It's an aerodynamics problem. SpaceX has designed both of their Dragon capsules to be inherently stable for reentry; should the capsule not be able to orient itself actively due to a Draco engine failure - it will passively orient itself during reentry with the blunt heatshield pointing forward, into the velocity vector. This minimizes risk and ensures the ...


25

It would be possible to design a check valve chain of high reliability of closing, but it would restrict flow and start to increase the risk of one valve sticking shut. You would probably also need pressure sensors between the valves to determine system state, so you end up with a large number of pipe to fitting joints that are potential leaks and a bunch of ...


23

It was a real failure (albeit triggered externally rather than accidentally), just not the only failure that can happen. and it is the worst case of a series of the most likely failure scenarios: multiple engine failure. If you want to test every conceivable way a rocket can fail, you're looking at thousands if not hundreds of thousands of possible failure ...


22

If you're just looking at it as a mass trade, then yes, you will definitely get a mass savings by replacing a portion of your propellant with a bag full of nylon. Depending on your speed, the nylon can have a much higher "Isp" than the rockets. However at the system level, there are other things to consider besides mass. First, parachutes are not "hyper-...


22

Two things. Human-rating a rocket is a long, expensive process See this questions for more informations What exactly does it mean to human-rate a rocket? As opposed to the escape system? Every single design aspect and component of your rocket will be studied and need to be approved for human launches. The rocket must also pass more stringent requirements ...


21

NASA has only contracted for flights with 4 astronauts, since the complement of the station is a maximum of 7 in the long term. The limit of 7 has many reasons, but some are for sleeping accommodations and life support systems capacity. Soyuz can carry 3. Thus the current complement of ISS is limited to 6 (two Soyuz craft) at the moment. Bringing 7 to ...


20

In addition to not wanting to change anything for crewed launches (as geoffc mentioned), adding crew to a fueled vehicle is a seriously dangerous move. If you look at the AMOS-6 failure you'll see that the launch abort system probably would have saved any crew that was already on board. However, if the crew was actively being loaded, we would have lost not ...


18

You seem to think they were testing in ideal conditions. That's as far from truth as you can get. The abort happened at the moment in flight with worst aerodynamical conditions (called maxQ), when booster flies still low enough in atmosphere for significant drag to be present, yet fast enough already. If Dragon can escape at this moment, it can escape at any ...


16

Note that this answer refers to the final flight version of the Dragon V2. The first powered landings will be using parachutes before the system is validated for powered-only landing (see this article, thanks to Mark Adler for pointing this out). Parachutes are passive devices that slow the vehicle but do not steer it (some parachutes can steer a bit, ...


16

They didn't blow it up. They simply knew it would break up. A rocket is a very frail thing. It can only maintain it's structural integrity in forces it was designed to handle. When the Dragon left, the Falcon no longer had an aerodynamic nose cone. So supersonic wind forces pitched it sideways and the body of the rocket could not stand that force from that ...


15

When the space shuttle was in operation, it could carry as many as seven extra people, bringing the total population of the ISS up to ten. Three crew members is the standard permanent capacity of the space station, but the ISS can actually hold more. Ten is the working limit. In practice, the maximum number of people the shuttle carried was eight, and that ...


15

Musk indicated that Dragon 2 could be reused "with minimal rework and fueling" about 10 times between overhauls. This is the target number but these are early days. The previous ablative shield was dumped in favor of a more advanced design. The goal then, for heat shield, engines and other major components would be at Least 10 flights, in theory. Regards ...


15

E. Musk has answered this multiple times in interviews. This comes down to the economics of it. They are putting this entire system together to haul cargo, and the reusable portion is there to increase profits. They are putting in place a reusable restartable engine in order to have the maximum duplication of function for the components onboard. Previously ...


15

Now we've had the Crew Dragon In Flight Abort test, this can be answered more definitively. I've not found a stream where it's absolutely crystal clear, but in the NASASpaceFlight coverage, you can hear the countdown net in the background - sometimes being spoken over by Chris G. A timeline of critical events: ~T-45 minutes, the Crew Access Arm is ...


13

That is an anechoic chamber. An anechoic chamber ("an-echoic" meaning non-reflective, non-echoing or echo-free) is a room designed to completely absorb reflections of either sound or electromagnetic waves. They are also insulated from exterior sources of noise. The combination of both aspects means they simulate a quiet open-space of infinite ...


13

It's got to be hugely expensive to transport and erect a Falcon even if you don't intend to launch it. The potential for damaging part of the rocket in the test makes it even less attractive. Why use a real rocket if a truss suffices? After Apollo's first abort test from a low platform in the desert, they also did several in-flight abort tests by ...


13

What is the primary reason for SpaceX motion to have astronauts board Dragon before fueling up the rocket? From what I understand though, it shouldn't be necessary - Falcon 9 and Dragon 2 have enough payload capacity and delta-V to reach ISS with nominal payload, on non-supercooled oxygen. For better performance they are switching to supercooled fuel. ...


12

According to Aviation Week, it's 4 Merlin 1D engines per week. The same article says they're planning 12 Falcon 9 launches in 2014. In October 2014, SpaceX announced they'd completed the 100th Merlin 1D. According to that article, build tempo was 4 engines per week at that point, and 80 Merlin 1Ds had flown by then. This engine was slated to be flown on a ...


12

Dragon V2 (Crew Dragon) uses 8 SuperDraco engines with maximum of 73,000 N thrust each. So, in theory, it could produce enough thrust to lift about 50,000 kg off the pad at thrust-to-weight ratio (T/W) of ~ 1.19. You need T/W larger than 1 to lift off the ground, and some more. T/W of ~ 1.2 is low for a launch vehicle and is usually closer to ~ 1.5, but let'...


11

One of the official purposes is to test the docking. It seems unlikely that this could be considered complete if the hatch is never opened. And if the hatch is opened, odds are very good the astronauts will enter it at some point in time, if nothing else then for a PR moment.


11

It seems that someone on the /r/spacexlounge subreddit had the same question: We know from the FAA filing for the pad abort that Dragon has a fuel capacity of 1388kg, and we know that it's max landing mass should be around 8.9 tonnes. If we round that up to 9 tonnes, and then plug in the specific impulse for SuperDraco of 235 seconds, we get a Delta-...


11

The nose cone for crew dragon protects not only the docking port but four forward Draco thrusters and the star tracker too. It has similar function to the Dragon v1 GNC bay door by protecting the GNC equipment when in atmosphere. So the nose cone stays open most of the time to allow for navigation. On top of that it looks like these four thrusters are the ...


10

Revisiting this question 4 years later, it seems clear that while they had this estimate of the engine build rate, they did not hit it. There was an Instagram post of the 400th completed engine Dec 2017. So they clearly did not hit this run rate, nor sustain it if they meant Merlin engines. However, in that interim they have launched 45 Falcon 9 flights, ...


9

Dragon 2 does have aerodynamic controls. It contains a movable ballast sled (written statement by Garrett Reisman for a congressional-hearing), which can be used to change the craft's attitude: a movable ballast sled allows the angle of attack to be actively controlled during entry to further provide precision landing control.


9

That's 1,388 kg of propellant for the whole vehicle, not per engine. Reading the original document referred to by Wikipedia, it says 3,060 pounds of propellant for the Crew Dragon capsule. (It's on page 8. The fuels are NTO and MMH and the combined weight of both is given.)


8

The best I've been able to come up with is interior shots from the unveiling and of the test article (complete with test dummy), but I'd say the visual difference is a pretty compelling argument that at least the hull of the test vehicle isn't the one used in the unveiling: A still from the video of the unveiling, Elon climbing in: Test vehicle with test ...


8

The CST-100 heat shield is replaced each flight because it is discarded as part of the landing process. The capsule has airbags, between the heat shield and bottom of the capsule. As the parachutes slow it down for landing, it discards the heat shield, inflates the airbags, and lands on the ground. Thus they can never reuse a heat shield, they throw it ...


8

Some engines will be used on the grass hopper platforms. Some engines will presumably fail during qualification/smoke (pun not intended*) testing. Some engines will end up in the stock pile for future launches. But I am guessing most of the remainder will be used for R&D testing, while improving the design [Merlin C => Merlin D & Merlin D => ...


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