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About Racescort666

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  1. The BE-3 seems like it would be kind of overpowered for a lunar lander. With a lunar TWR of 2 you could have a 165t spacecraft. Whether that's the mass you're deorbiting or trying to lift off the surface, it's still huge.
  2. Racescort666

    Atlas Photo Dump

    ULA Posted a link to the SDASM's Flickr album: https://www.flickr.com/photos/sdasmarchives/albums/72157649485000247 I posted a few of the ones I really liked but the album is HUGE so enjoy.
  3. Racescort666

    Is the Carter(Doomsday) hypothesis valid?

    Consider this: humans like all life on earth and presumably elsewhere is constantly evolving. So at what point did Homo heidelbergensis start becoming Homo sapiens? Then at what point does Homo sapiens start becoming something else? Have all of the humans died off after this? At what point does the population stop becoming human and start becoming something else? It's not really a doomsday scenario in this case just an estimate of evolutionary progress. Also worth noting: correlation =/= causation.
  4. Racescort666

    Ignition! to be reissued

    Our favorite rocket fuel book is going back into print and will go on sale on May 23rd: http://a.co/0CIWrIf Unfortunately, the original book is now even more expensive.
  5. Racescort666

    Orbital ATK launch and discussion thread

    I guess I'm glad I didn't fly out there to watch this.
  6. Racescort666

    Ozone oxidiser?

    For giggles I decided to look for a nitroglycerin MSDS and I came across this: https://www.epa.gov/sites/production/files/2015-05/documents/9530603.pdf Exciting stuff.
  7. The thing that kills me is that ULA says that they aren't interested in propulsive landing because it will impact the booster performance (basically increasing dry mass for recovery) but then they go on to say that the Atlas V has this huge extra capacity and they rarely use it to the full potential. Well which is it? Surely the few situations where the Atlas V needs the full performance a fully expendable configuration can be flown but in the others, you could at least try.
  8. They have a very convenient rocket for testing this stuff too: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100037917.pdf
  9. Racescort666


    Based on this information, the tip speed is Mach 0.72; not crazy considering processing blade mach numbers are usually pretty high.
  10. Racescort666

    ULA launch thread

    The company I work for has a metal 3D printer and the rule of thumb is that as manufactured surfaces are good enough for things like bolt holes and mounting brackets. Pressed in parts like bushings or spherical joints need machining but it’s easy for them to add machine stock. I don’t really know what they need to do for seals. I suppose it depends on the joint design but you’re absolutely right, way less machine time is required. The other thing that isn’t immediately obvious is that with one or a team of people building these things by hand, it is very hard to increase production capacity. It takes a long time and is very difficult to get people with that kind of skill level. With a 3D printer, if you want to increase production capacity, you buy more 3D printers. Yeah, it’s expensive but so is training.
  11. Racescort666

    ULA launch thread

    Interesting statement from Bruno though: “Key determining factors to our selection included price and delivery schedule,” said Bruno. “We look forward to continuing our strong partnership to ensure a successful introduction of Vulcan Centaur.” The new engine is supposed to be 3D printed so I wonder if that has had a huge cost save? I would imagine there would be some save with less manual fabrication but 3D printing parts that big out of metal still isn’t cheap.
  12. Racescort666

    For Questions That Don't Merit Their Own Thread

    fluids... dampen... lol... I suspect yes but I'm not the right person to answer, I just wanted to make a joke about fluids dampening.
  13. Racescort666

    ULA launch thread

    @sevenperforce, not that it's relevant to what you're working on but ULA offers a 5m metallic fairing (all of the others are graphite epoxy sandwich structure) which is a modified Titan IV fairing. The Titan rocket lives on to some degree.
  14. Racescort666

    ULA launch thread

    Their website doesn't list a D-IV (4,2) but the users guide still talks about it (2013 publish date). It does not mention a non-SRB Delta IV Medium. Going by the payload numbers, I suspect that something that wouldn't need SRBs on a Delta IV would be better suited to fly on an Atlas V. I suspect that Atlas V is also cheaper to fly especially in 401 configuration.
  15. So I wasted spent a ton of time analyzing pictures and trying to scale NG to find a tank to fuel correlation that made sense to no avail. Then I realized that doing this by thrust, ISP, and dV, I could probably get a ballpark much easier. Super Rough estimate: 250 t - 125 t just based on thrust and the knowledge that BE-4 can throttle to 50% so the minimum that the dry mass can be is 50% of the BE-4 SLT otherwise it can't hover. That being said, if the lower stage is 250 t at stage separation and the booster touches down just as the mass gets to 125 t, it uses about 2175 - 2400 m/s of dV. The discrepancy is with how you calculate dV: vacuum vs SL ISP, the values I used are found here. Also, 250 t... at stage separation... have I mentioned this thing is huge yet? The New Glenn booster, at stage separation, will probably weigh as much as an Atlas V booster FULLY FUELED. Now the next question, is this reasonable? By my estimate, on both the low side and high side, yes. I find myself continually adjusting my spreadsheet to principally give a conservative result based on assumptions. Basically, regardless of how I calculate landing dV (thus fuel), the numbers work out to something that seems reasonable. How much fuel is needed for landing? I really have no idea. Well, if the requirement for booster recovery is 2.2(ish) km/s, you get booster separation masses 397 t - 372 t and dry masses in the 212 t - 172 t range; assuming you have a landing mass that corresponds to approximately 75% of throttle maximum for 1 engine. Simplest ballpark answer: 187.5 t this is the ground level TWR mass of 75% throttle, given the 2400 kN of thrust. I probably didn't need to waste spend as much time on this as I did but vanity prevailed and I didn't really get the good estimate I wanted.