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Everything posted by mikegarrison

  1. $/launch for their payload is the key number for the customer. (Along with reliability, availability, etc.) If I have a 100 kg payload and SpaceX can launch it on a Starship for less money than Rocketlab can launch it on a Neutron, then great! But obviously SpaceX's launch cost is probably going to be higher, so if they can't fill up their rocket with other payloads on the same launch, they aren't going to be able to give me that price that is better than Neutron. If it costs less to launch a Falcon than a Neutron, then Rocketlab is just screwed. But if Neutron costs less per launch, even if it doesn't cost less per kg, then they have an opportunity. If my payload is the only one going up and it can fit on either rocket, then I don't care what the $/kg cost is. I care what the $/launch cost is.
  2. But you can't. Not unless the flight was something like an equipment repositioning flight (ie. a "redeye" flight).
  3. It makes no sense to fly 50 people 200 miles on an A380, when an RJ would do the same mission for much less. A "right-sized" flight vehicle has a huge advantage over one that is over-capacity for the required job. The issue, though, is that if you design your vehicle to be perfectly sized for one specific job, you can't handle even a slightly bigger job. So it's all a tradeoff between trying to not over-size the vehicle too much but also sizing it big enough to capture enough market.
  4. In a long-ago time in my career I did combustor design. Fixing hot spots was always considered a bit of a "black art", but back then we had far fewer computational resources available to us. The testing was always somewhat statistical in nature, because in combustion physics things don't always repeat. And sometimes tweaks that you thought would be insignificant actually turned out to not be so.
  5. Robert, I have noticed that you often use PD-type estimation tools and assume they are more correct than the numbers provided by the companies that actually have done all the detail design and manufacturing of the hardware in question. I suggest you might want to rethink the accuracy of that approach.
  6. I suggest this is the wrong forum to be discussing the imaginary pseudo-science of Star Trek.
  7. There are many reasons why the US might want to further cement relationships with Europe w.r.t. space, but going in to them would almost certainly violate this board's policy on political discussion.
  8. What does "CAA Tower" mean? Is this some acronym for the launch tower? edit: "crew access arm"?
  9. I think that they require relatively concentrated ore. It's not like you find nuggets of neodymium or whatever, but some sites have (relatively) higher concentrations than others. So while there is no such thing as a "vein" of REEs, I don't think you can expect a commercially successful yield from processing any random pile of dirt. But I'm not a geologist or mining engineer, so maybe my understanding of this is wrong.
  10. Um ... just here to tell you that Musk did not invent engineering. Reducing part counts and lowering costs is what engineers have been doing since at least the Roman Empire. Also, "rare earth" elements are not rare. It's just that they are not concentrated. So unless you find a really unusual concentration of them all in one place, the main thing that is involved in producing them is digging a *lot* of material and processing it with a *lot* of byproduct. China managed to capture most of the world's rare earth production simply by being willing to do it on a scale that made it less expensive. (And also by not really worrying too much about the environmental costs of mining so much material in order to produce so little output.) But it's not like China has some sort of inherent and unassailable lock on the production of rare earth materials.
  11. Can't they just drill for "ore" and turn it into anything they want?
  12. Kind of looks like he is preparing to cut it loose while recovering as much of his personal money as he can.
  13. That would be a new one. Not one of the two USAF already owns (and USSF operates).
  14. Those are all solid-fuel rockets, right?
  15. Boeing does not own the X-37B and (AFAIK) has zero say on what launch vehicles the USSF chooses to launch it on.
  16. Good to know our precious Ares rockets are so well-protected.
  17. I see, thanks. So a catenary wire is a wire that follows a catenary curve, which is to say the natural curve that an untensioned suspended wire follows between any two points. This seems like confirmation for what it visually looked like to me about those not being tensioned guy wires. They probably act as both current paths and maybe even sort of a widely spaced Faraday cage? Thus the "cone of protection"? (I am not an electrical engineer.)
  18. I thought I was quite clear about what wires I was talking about. I guess not? I was talking about the wires that go to the ground in all directions from the very top of that tubular structure that sticks out from the top of the tower. They are clearly not "ziplines". My assumption is that they are current paths for lightning protection, but I was wondering if anybody here knew that for sure.
  19. So on the launch tower there is a round spire or exhaust stack sticking up. And then there are wires running from that structure to (apparently) the ground. But the wires don't seem to be in a lot of tension. Are those wires grounding for lightning protection? Or maybe are they under more tension than they look like, and they are guy wires?
  20. Betcha every landing on the tower has an elevator door. Certainly appears to be the same number of stops as appears to be landings in this picture.
  21. There are multiple definitions of "1.5 stage", but most typical is a booster/sustainer setup, like for example the Space Shuttle or the original Atlas rocket. A lower-thrust, long burning "sustainer" and high power "booster" are ignited together at launch. Then when the booster burns out, it is dropped. The "sustainer" continues burning all the way up to orbit. (The Space Shuttle typically completed its orbital insertion using the OMS engines, so it could be argued that it was a 2.5 stage rocket rather than a 1.5 stage rocket.) Typically the booster is high-thrust, low-ISP, and the sustainer is low-thrust, high-ISP. Hydrolox is the most common choice for sustainer stages, although the Atlas rockets (such as those that put the Mercury spacecraft into orbit) used kerolox for the whole thing.
  22. I really think ethanol is the ideal rocket fuel. If it doesn't get you to orbit, at least it can get you to where you don't care about not getting to orbit.
  23. Have you considered that maybe it was just a bad idea that they finally got around to accepting as a bad idea?
  24. Me: In the song This Land Is Your Land, how did Woody Guthrie know what the other side of the sign said? ChatGTP: "This Land is Your Land" is a famous folk song written by Woody Guthrie in 1940. The song was written as a response to another song called "God Bless America," which Guthrie felt did not accurately reflect the experiences of everyday Americans, particularly those affected by poverty and injustice. In the song, Guthrie sings about passing by a sign that reads "Private Property" and then notes that he knows what the other side of the sign says: "No Trespassin'." This line is meant to symbolize the exclusion and inequality that many people faced in the early 20th century. It's not specified in the song how Woody Guthrie knew what the other side of the sign said. It's likely that Guthrie, who traveled extensively throughout the United States during the Great Depression and Dust Bowl era, had seen similar signs and was using this imagery to illustrate a larger point about the unequal distribution of resources and opportunities in the country. ======== LOL. First of all, there are multiple versions of the lyrics. In one of them (the original manuscript), the sign says "Private Property". In another (the one that can be found on Woodyguthrie.org), the sign says "No Trespassing". But in both versions, the other side of the sign "didn't say nothing". And any human knows *exactly* how Woody knew what was on the other side of the sign. That's the kind of thing nobody has to tell us, but that Chatbots don't understand.
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