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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.

AnteayerSalida Principal

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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