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11
As this is in the news again I figured I'd go look for pictures, video or *anything* that gives us an impression of what it is.. can someone save me the effort?

I thought I did. The second post in this thread has a link to the complete patent application, including 20 pages of illustrations starting on page 51 of the pdf file. Figure 21 (page 65) is a drawing used to 3D print a 9-bladed test article. Figure 26 shows the thing built with triangular electrodes. Figure 29 shows a carbon nanotube implementation.

Only effort needed is to read the 1st 2 posts, follow a link and click. Have fun.
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Blue Origin / Re: New Glenn 3-Core Version
« Last post by edzieba on Today at 11:49 am »
"There's three rockets. You glue them together. How hard is that? Well, according to my team, it's really hard." -- Gwynne Shotwell
but how hard is it if you don't refuse to use existing industry knowledge?
Still really hard, you just have a grizzled veteran engineer to tell you it's really hard.
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Primary launch opportunity = 2024-04-22 23:10:00 UTC per CelesTrak. (Presumably delayed from 22:40 because of weather.)

https://twitter.com/TSKelso/status/1782315792325071246

Quote from: T.S. Kelso
CelesTrak has pre-launch SupGP data for the @Starlink Group 6-53 launch from Cape Canaveral on 2024-04-22 at 23:10:00 UTC: https://celestrak.org/NORAD/elements/supplemental/table.php?FILE=starlink-g6-53. Deployment of 23 satellites 2024-04-23 at 00:15:06.340 UTC. Data for 6 backup opportunities also provided: https://celestrak.org/NORAD/elements/supplemental/.

https://celestrak.org/NORAD/elements/supplemental/

Launch: 2024-04-22 23:10:00 UTC. Deploy: 2024-04-23 00:15:06.340 UTC.
Launch: 2024-04-22 23:34:00 UTC. Deploy: 2024-04-23 00:39:06.340 UTC.
Launch: 2024-04-23 00:44:00 UTC. Deploy: 2024-04-23 01:49:06.340 UTC.
Launch: 2024-04-23 01:10:00 UTC. Deploy: 2024-04-23 02:15:06.340 UTC.
Launch: 2024-04-23 01:26:00 UTC. Deploy: 2024-04-23 02:31:06.340 UTC.
Launch: 2024-04-23 02:28:00 UTC. Deploy: 2024-04-23 03:33:06.340 UTC.
Launch: 2024-04-23 02:40:00 UTC. Deploy: 2024-04-23 03:45:06.340 UTC.
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Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.
The point of RDREs is not increased efficiency or performance: turbomachinery-pumped engines can already get pretty close to the theoretical limits there. The point of an  RDRE is to achieve the same combustion pressures and temperatures without the turbomachinery, giving you an engine with the mechanical complexity and (similar) mass of a pressure-fed engine but the performance of a turbopump engine. Improved TWR with fewer moving parts.
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Space Science Coverage / Re: NASA - Chandra X-Ray - spending cuts
« Last post by hoku on Today at 10:33 am »
<snip>
The are a couple of strategic questions here.
<snip>
3/ What is the relative importance of different wavelenghths?
The relative scientific importance of different wavelength regions is open for discussion. A physical fact is that a large fraction of the electromagnetic spectrum are blocked by Earth's atmosphere, and that astrophysical signals reaching ground-based observatories are degraded by, e.g., atmospheric seeing and atmospheric emission. Short-wavelength observations of the extreme UV, X-rays and gamma-rays require space-based observatories.

The US community also has access to the ESA-led XMM-Newton, which has a larger collecting area, but worse angular resolution than Chandra. Like Chandra, XMM was launched in 1999. Its operation is currently funded through 2026, with another 3-year extension until 2029 being anticipated. The International X-ray Observatory (IXO), a joint NASA-ESA-JAXA follow-on mission, was cancelled by NASA in 2012. Athena, the ESA-led "replacement" for IXO, recently went through a major crisis, with "New Athena" now expected to launch not earlier than the late 2030s.

https://science.nasa.gov/mission/xmm-newton/

https://en.wikipedia.org/wiki/International_X-ray_Observatory

https://asd.gsfc.nasa.gov/athena/
16
Blue Origin / Re: New Glenn 3-Core Version
« Last post by JCRM on Today at 10:15 am »
"There's three rockets. You glue them together. How hard is that? Well, according to my team, it's really hard." -- Gwynne Shotwell
but how hard is it if you don't refuse to use existing industry knowledge?
17
Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

The detonation velocity of methalox is about half the exhaust velocity of a Raptor.
An RDE engine has the detonation wave front circling at right angles to the exhaust flow so the detonation speed is not a limit on the exhaust velocity.  What is an issue is that a nozzle does not provide a significant gain in Isp as the collimation of the exhaust is set by the slot geometry.
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SpaceX Starship Program / Re: The Starbase pilgrimage thread
« Last post by edzieba on Today at 09:50 am »
With all the infamy that Boca Chica's mud holds, it sounds like someone could do a roaring trade in personal hovercraft rental. 
19
Spaceflight Entertainment and Hobbies / Re: Space Stamps
« Last post by salyut on Today at 09:48 am »
December, 29, 1966, Hungary.
20
Sobering to see that the IFT-3 design could not lift as much as even an expendable Falcon Heavy, or a New Glenn, despite making more than twice as much liftoff thrust as a Saturn V.  Much potential to grow, obviously, but the bar is high.  Saturn V could put 141 tonnes in LEO (3.5 times more than IFT-3) or, more importantly, 52.76 tonnes to TLI - more than IFT-3 could get to LEO in theory.   Even the growth Starships won't lift as much beyond LEO without need for multiple refueling launches.

NASA contemplated a steel Shuttle orbiter, but chose Aluminum for weight.  The steel Starship is going to be a weight shedding challenge.

 - Ed Kyle

Justin's Davenport's recent roundup article did some computations on the thrust of both the booster and Starship engines, which showed that they were substantially throttled--either that, or there was significant underperformance off of the 230t benchmark number for the RSL v2.

It's certainly possible that something serious is preventing SpaceX from moving to 100% throttle.  But it seems more likely that they're just under-throttling because they can, and it improves their chances of doing successful tests.

I'll wring my hands with the best of 'em, but I don't think it's time to panic until we see real Starlinks launched--and even then, the doglegs required will make it really hard to get a good performance number to the 200 x 200 reference.

I predict that things will be even more obfuscated by the introduction of Starship v2, which appears to have an RSL that's pushed closer to 250tf, which is halfway between the rated 230t for RSL v2 and the 270tf that RSL v3 would be capable of at 350bar.  (When I computed this, I didn't widen the throat, so it might be a bit more than this.)

If Starship v2 doesn't wind up close to 150t to 200 x 200, then there's probably something (somewhat) bad happening.

Well on IFT-2 they did have to carry extra O2 which they then had to dump leading to the loss of Starship so perhaps SpaceX just tried throttling down some more after analysing the data.
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