SpaceX Completes Static Fire of Starship Prototype, Will Hop Next (arstechnica.com) 32
After scrubbing several attempts for weather concerns, technical issues, and even a range violation due to a nearby boat, SpaceX succeeded in static-fire testing the latest prototype of its Starship vehicle on Thursday. Ars Technica reports: At 3:02pm local time in South Texas, the single Raptor engine attached to the Starship prototype dubbed Serial Number 5, or SN5, roared to life for a few seconds. In video shared by NASASpaceflight.com, the test appeared to be nominal, evidently providing SpaceX engineers with the confidence they need in the latest iteration of Starship. Shortly after the test, the founder and chief engineer of SpaceX, Elon Musk, confirmed that the static fire meant the company now plans to move forward with a short test flight of the vehicle. Based upon a notification from the US Federal Aviation Administration, this 150-meter flight test could take place as soon as Sunday, with a launch window opening at 8am local time (13:00 UTC). This would be the first flight test of Starship hardware since a stubby prototype -- Starhopper -- soared to 150 meters in late August 2019. That test, in which a single Raptor engine powered the vehicle upward and laterally for about 100 meters before landing, was successful in demonstrating thrust and vector control of the methane-fueled engine.
Key difference (Score:5, Interesting)
Starhopper was built like a watertower - with no need to be sufficiently light, sufficiently high-pressure tolerant, tolerant of high aero or reentry stresses, etc. Starship, on the other hand, has to be able to withstand all of these in order to become an orbital-class vehicle.
Of course, I not only expect SpaceX to crash some Starships during flight testing, but also to blow up some more on the test stand while trying to find the bounds of how high pressures they can get vs. how lightweight they can build the craft. "Fail quickly" is a good strategy for rapid development where there's no human lives at stake.
One thing that'll be fun to see in the future, after the first orbital landing, is how Starship looks. Highly heated stainless steel can get a rainbow effect on it, which would look awesome :)
Re:Key difference (Score:5, Interesting)
The explosions should get ever-more spectacular, too ;) Starship + SuperHeavy combined will hold over 1500 tonnes of methane, which burned with oxygen equals about 8e13 joules of energy, or 19 kilotonnes of TNT equivalent, about 25% more than the Hiroshima bomb. By comparison, the N1 pad failure was about 7kt, and the Halifax Explosion was 2,9kt. Now, to be fair, destructive potential is not just about total energy, but also how quickly it's released (power) - but still....
The last Starship failure was really bloody impressive; I can't imagine what a full stack would look like.
Apollo (Score:1)
Re:Apollo (Score:5, Informative)
Software was pretty limited back in those days. For example, Apollo's guidance computer used "core rope memory" ROM, which was literally woven by hand. That said, NASA in general wasn't as heavily bogged down by "analysis paralysis" in those days as they are today. And they did do uncrewed test flights. Combining the previous two sentences: Apollo 6, for example - uncrewed flight, they found that they had severe pogo oscillations, caused a propellant problem (rupture in a flexible line, replaced with a rigid one after this) that lead to the shutdown of one of the J2 engines which - due to a miswiring in the rush - caused the computer to accidentally shut down a second, perfectly fine engine. But they gathered a huge amount of information, rapidly iterated, and just a bit over a year later, landed on the moon.
For SpaceX, there's a massive amount of development work left. Beyond all of the work involved in finishing Starship's suborbital test program (still yet to hop, let alone do high altitude controlled flights and land safely), and Super Heavy (barely even started, although thankfully built extremely similar to Starship) - and then to test them on orbital stacks, including reentry for both - SpaceX will need to continue to work to increase performance and decrease the mass of the system (e.g., how much payload you can deliver per flight) while simultaneously increasing reliability, with the goal of hitting airplane levels of reliability and reuse. AND they need to get orbital propellant transfer to work if their lunar and Mars plans are to be realized, AND they need to develop a range of variants of Starship, including crew, payload, lunar, and tanker.
Increasing performance and decreasing mass involves iterating on every single system aboard, from the engine to the tankage walls. To pick a random example: they'll initially be flying it with cold gas RCS thrusters. But they plan to develop methalox RCS thrusters - more complicated, but significantly more powerful and higher ISP. This would not only save propellant (for a given required impulse), but would likely allow them to land without having to do an overshot "fishhook" turn driven by the raptors that requires a longer burn time.
Lots and lots and lots of work ahead. But it'll be nice to see an orbital-class version of this bird take to the skies :)
Re: (Score:2)
For some reason I'm much more confident in SpaceX's ability to gradually optimize the Starship stack and get more payload than I would be with anyone else out there. Their approach seems perfectly normal if you do modern software development, of course, but it's apparently shocking in modern rocketry.
It was surreal to hear Bridenstine talking about this, how they were too skeptical of SpaceX in the Commercial Crew Program because their iterative development model was so different from what NASA was used to
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Iterative development makes perfect sense in situations where prototype + testing is cheap, like with software. But with hardware, you want as few iterations as possible because each iteration you must actually build the thing which costs money and takes time. Electrical Engineering teams consider it a matter of pride if they can get their board to work with only one prototype because it saves so many weeks of lead time. They sometimes hand-solder fixes to the board to avoid another round of prototypes.
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SpaceX can now make the tanks quite quickly, and the Raptors have to be mass produced either way, since each launch stack will require dozens. Loss of a fully orbital-ready Starship would be more significant, of course.
Switching to stainless from carbon fibre made the material cost per vehicle dramatically lower. That wasn't the main motivating factor, mind you, just a convenient side effect.
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For example, Apollo's guidance computer used "core rope memory" ROM, which was literally woven by hand.
Back in the nineteen hundreds, all core memory was "literally woven by hand." Asian women alone had the patience it took to thread intersecting read and write wires through arrays of those little iron rings. That's why only supercomputers could justify having a full megabyte of the stuff.
Re: Apollo (Score:2)
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Every time you troll this ventilator nonsense, you'll get the same fact check, no matter what variant of trolling you use. [slashdot.org]
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I admit I'm jealous.
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Still waiting on those ventilators conman.
Trolls! Custom trolls! Alive, alive O!
pedantic (Score:2)
I suppose it would be pedantic to think that it shouldn't be called a Starship unless it has the power to leave the solar system.
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Boeing's crew spacecraft is called Starliner and isn't designed to even leave Earth orbit.
A name is just a name. Dragon has nothing to do with dragons. Falcon has nothing to do with falcons.
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And its hardly a liner too. IMO a liner needs to hold at least a few hundred passengers, be part of an actual "line" with regular service to set destinations and do so in style and comfort.
All spaceships get style points by default. But from what I've seen there is nothing luxurious about it. Service is definitely not regular since we don't even know when the next test is. And 7 crew is not 100+ passengers.
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If you want to be pedantic, it's not a starship, it's Starship, a proper noun as you correctly capitalized, just a branding choice, like their Starlink satellite constellation or Boeing's Starliner capsule.
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"I suppose it would be pedantic to think that it shouldn't be called a Starship unless it has the power to leave the solar system."
Well, these STARgazing people are made of STARdust. You may be STARtled, but this STARtup has done STARtingly good 'til now.
Dont' STARve yourself, eat some STARfruit.
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Re: pedantic (Score:2)
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It's Fun To Watch the Iterations (Score:4, Insightful)
I'm going to enjoy watching Starship slowly prove itself and eventually find its way to the Moon, while Boeing is still fumbling around with SLS/Orion.
The Raptor engine itself is very impressive (Score:5, Informative)
Advantages of methane (Score:2)
Well, the reason why hydrogen-oxygen would have a higher specific impulse would be the energy density of hydrogen. But, from what I've read there are numerous advantages to using methane as a fuel that can make it better than hydrogen.
A non-exclusive list, working from memory:
1. Methane can be obtained more or less directly, you need to do chemical processing to obtain hydrogen. So it is cheaper.
2. Methane and O2 have similar liquefaction points - O2 is ~90K, Methane 111K, hydrogen is only 20K. This si
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I would add that Hydrogen from what I remember also has a nasty tendency to attack/weaken the metals of the tanks/engines over time, making it a bit difficult to use for reusable systems.
https://en.wikipedia.org/wiki/... [wikipedia.org]
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I remain somewhat skeptical that SpaceX's Starship will do all the things they intend it to at nearly the price point they say it will...
I'm quite confident they will get there, both in capabilities and the desired price point. I just expect it to take most of the next decade to finally get there. There's a lot of work left, but we do know that stainless steel is cheap. They just have to get better and better at manipulating it, until the process is also cheap. It can be done. It will take time.