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Ayer — 21 Noviembre 2024Salida Principal

Measuring the Mighty Roar of SpaceX’s Starship Rocket

Por: Tom Nardi
21 Noviembre 2024 at 12:00

SpaceX’s Starship is the most powerful launch system ever built, dwarfing even the mighty Saturn V both in terms of mass and total thrust. The scale of the vehicle is such that concerns have been raised about the impact each launch of the megarocket may have on the local environment. Which is why a team from Brigham Young University measured the sound produced during Starship’s fifth test flight and compared it to other launch vehicles.

Published in JASA Express Letters, the paper explains the team’s methodology for measuring the sound of a Starship launch at distances ranging from 10 to 35 kilometers (6 to 22 miles). Interestingly, measurements were also made of the Super Heavy booster as it returned to the launch pad and was ultimately caught — which included several sonic booms as well as the sound of the engines during the landing maneuver.

Sounds were measured at eight different locations.

The paper goes into considerable detail on how the sound produced Starship’s launch and recovery propagate, but the short version is that it’s just as incredibly loud as you’d imagine. Even at a distance of 10 km, the roar of the 33 Raptor engines at ignition came in at approximately 105 dBA — which the paper compares to a rock concert or chainsaw. Double that distance to 20 km, and the launch is still about as loud as a table saw. On the way back in, the sonic boom from the falling Super Heavy booster was enough to set off car alarms at 10 km from the launch pad, which the paper says comes out to a roughly 50% increase in loudness over the Concorde zooming by.

OK, so it’s loud. But how does it compare with other rockets? Running the numbers, the paper estimates that the noise produced during a Starship launch is at least ten times greater than that of the Falcon 9. Of course, this isn’t hugely surprising given the vastly different scales of the two vehicles. A somewhat closer comparison would be with the Space Launch System (SLS); the data indicates Starship is between four and six times as loud as NASA’s homegrown super heavy-lift rocket.

That last bit is probably the most surprising fact uncovered by this research. While Starship is the larger and more powerful  of the two launch vehicles, the SLS is still putting out around half the total energy at liftoff. So shouldn’t Starship only be twice as loud? To try and explain this dependency, the paper points to an earlier study done by two of the same authors which compared the SLS with the Saturn V. In that paper, it was theorized that the arrangement of rocket nozzles on the bottom of the booster may play a part in the measured result.

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Hackaday Links: November 3, 2024

4 Noviembre 2024 at 00:00
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“It was the best of times, it was the blurst of times?” Perhaps not anymore, if this Ig Nobel-worthy analysis of the infinite monkey theorem is to be believed. For the uninitiated, the idea is that if you had an infinite number of monkeys randomly typing on an infinite number of keyboards, eventually the complete works of Shakespeare or some other famous writer would appear. It’s always been meant to be taken figuratively as a demonstration of the power of time and randomness, but some people just can’t leave well enough alone. The research, which we hope was undertaken with tongue firmly planted in cheek, reveals that it would take longer than the amount of time left before the heat death of the universe for either a single monkey or even all 200,000 chimpanzees in the world today to type the 884,647 words of Shakespeare’s complete works in the proper order.

We feel like they missed the point completely, since this is supposed to be about an infinite number of monkeys. But if they insist on sticking with real-world force monkey labor, what would really be interesting is an economic analysis of project. How much space would 200,000 chimps need? What would the energy requirements be in terms of food in and waste out? What about electricity so the monkeys can see what they’re doing? If we’re using typewriters, how much paper do we need, and how much land will be deforested for it? Seems like you’ll need replacement chimps as they age out, so how do you make sure the chimps “mix and mingle,” so to speak? And how do you account for maternity and presumably paternity leave? Also, who’s checking the output? Seems like we’d have to employ humans to do this, so what are the economic factors associated with that? Inquiring minds want to know.

Speaking of ridiculous calculations, when your company racks up a fine that only makes sense in exponential notation, you know we’ve reached new levels of stupidity. But here we are, as a Russian court has imposed a two-undecillion rouble fine on Google for blocking access to Russian state media channels. That’s 2×1036 roubles, or about 2×1033 US dollars at current exchange rates. If you’re British and think a billion is a million million, then undecillion means something different entirely, but we don’t have the energy to work that out right now. Regardless, it’s a lot, and given that the total GPD of the entire planet was estimated to be about 100×1012 dollars in 2022, Google better get busy raising the money. We’d prefer they don’t do it the totally-not-evil way they usually do, so it might be best to seek alternate methods. Maybe a bake sale?

A couple of weeks back we sang the praises of SpaceX after they managed to absolutely nail the landing of the Starship Heavy booster after its fifth test flight by managing to pluck it from the air while it floated back to the launch pad. But the amazing engineering success was very close to disaster according to Elon Musk himself, who discussed the details online. Apparently SpaceX engineers shared with him that they were scared about the “spin gas abort” configuration on Heavy prior to launch, and that they were one second away from aborting the “chopsticks” landing in favor of crashing the booster into the ground in front of the launch pad. They also expressed fears about spot welds on a chine on the booster, which actually did rip off during descent and could have fouled on the tower during the catch. But success is a hell of a deodorant, as they say, and it’s hard to argue with how good the landing looked despite the risks.

We saw a couple of interesting stories on humanoid robots this week, including one about a robot with a “human-like gait.” The bot is from China’s EnginAI Robotics and while its gait looks pretty good, there’s still a significant uncanny valley thing going on there, at least for us. And really, what’s the point? Especially when you look at something like this new Atlas demo, which really leans into its inhuman gait to get work done efficiently. You be the judge.

And finally, we’ve always been amazed by Liberty ships, the class of rapidly produced cargo ships produced by the United States to support the British war effort during WWII. Simple in design though they were, the fact that US shipbuilders were able to ramp up production of these vessels to the point where they were building a ship every eight hours has always been fascinating to us. But it’s often true that speed kills, and this video shows the fatal flaw in Liberty ship design that led to the loss of some of the early ships in the class. The short video details the all-welded construction of the ships, a significant advancement at the time but which wasn’t the cause of the hull cracks that led to the loss of some ships. We won’t spoil the story, though. Enjoy.

Hackaday Links: October 20, 2024

20 Octubre 2024 at 23:00
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When all else fails, there’s radio. Hurricane Helene’s path of destruction through Appalachia stripped away every shred of modern infrastructure in some areas, leaving millions of residents with no ability to reach out to family members or call for assistance, and depriving them of any news from the outside world. But radio seems to be carrying the day, with amateur radio operators and commercial broadcasters alike stepping up to the challenge.

On the amateur side, there are stories of operators fixing their downed antennas and breaking out their field day gear to get on the air and start pitching in, with both formal and ad hoc networks passing messages in and out of the affected areas. Critical requests for aid and medication were fielded along with “I’m alright, don’t worry” messages, with reports from the ARRL indicating that Winlink emails sent over the HF bands were a big part of that. Unfortunately, there was controversy too, with reports of local hams being unhappy with unlicensed users clogging up the bands with Baofengs and other cheap radios. Our friend Josh (KI6NAZ) took a good look at the ins and outs of emergency use of the amateur bands, which of course by federal law is completely legal under the conditions. Some people, huh?

Also scoring a win were the commercial broadcasters, especially the local AM stations that managed to stay on the air. WWNC, an AM station out of Nashville, is singled out in this report for the good work they did connecting people through the emergency. As antiquated as it may seem and as irrelevant to most people’s daily lives as it has become, AM radio really proves its mettle when the chips are down. We’ve long been cheerleaders for AM in emergencies, and this has only served to make us more likely to call for the protection of this vital piece of infrastructure.

Windows 10 users, mark your calendars — Microsoft has announced that you’ve got one year to migrate to a more profitable modern operating system. After that, no patches for you! If Microsoft holds true to form, the scope of this “End of Life” will change as the dreaded day draws nearer, especially considering that Windows 10 still holds almost 63% of the Windows desktop market. Will the EOL announcement inspire all those people to migrate? Given a non-trivial fraction of users are still sticking it out with Windows 7, we wouldn’t hold our breath.

Speaking of Microsoft, for as much as they’re the company you love to hate, you’ve got to hand it to them for one product: Microsoft Flight Simulator. It seems like Flight Simulator has been around almost since the Wright Brothers’ day, going through endless updates to keep up with the state of the art and becoming better and better as the years go by. Streaming all that ultra-detailed terrain information comes at a price, though, to the tune of 81 gigabytes per hour for the upcoming Flight Simulator 2024. Your bandwidth may vary, of course, based on how you set up the game and where you’re virtually flying. But still, that number got us thinking: Would it be cheaper to fly a real plane? A lot of us don’t have explicit data caps on our Internet service, but the ISP still will either throttle your bandwidth or start charging per megabyte after a certain amount. Xfinity, for example, charges $10 for each 50GB block you use after reaching 1.2 TB of data in a month, at least for repeat offenders. So, if you were to settle in for a marathon flight, you’d get to fly for free for about 15 hours, after which each hour would rack up about $20 in extra charges. A single-engine aircraft costs anywhere between $120 and $200 to rent, plus the cost of fuel, so it’s still a better deal to fly Simulator, but not by much.

And finally, we were all witness to a remarkable feat of engineering prowess this week with the successful test flight of a SpaceX Starship followed by catching the returning Super Heavy booster. When we first heard about “Mechazilla” and the idea of catching a booster, we dismissed it as another bit of Elon’s hype, like “full self-driving” or “hyperloops.” But damn if we weren’t wrong! The whole thing was absolutely mesmerizing, and the idea that SpaceX pulled off what’s essentially snagging a 20-story building out of the air on mechanical arms was breathtaking. While the close-up videos of the catch are amazing, they don’t reveal a lot about the engineering behind it. Luckily, we’ve got this video by Ryan Hansen Space of the technology behind the catch, lovingly created in Blender. The work seems to have been done before the test flight and was made with a lot of educated guesses, but given how well the renders match up with the real video of the catch, we’d say Ryan nailed it.

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