Elon And Charlie

I went over to SpaceX this morning to hear them speak, with the first Dragon to go into space (it was a repeat of their show in McGregor, Texas yesterday with the Dragon that flew the recent mission). There are a bunch of pictures at SpaceflightNow. I don’t think I’m in any of them. I was standing in the press area, just below the vantage point of most of the shots.

You might see some bulges on the side of the Dragon to the right rear. I asked Elon if those were the pods and thrusters for the abort/landing motors. He said they were, but that the design was still in flux. I also asked him if there were cosine losses, and he said yes, that they are unavoidable, since you can’t thrust straight down from the side of a cone.

Speaking of Elon, he’s giving the commencement address at Cal Tech tomorrow morning.

28 thoughts on “Elon And Charlie

  1. ken anthony

    Could the configuration also contribute to stability and maneuverability? How far off of straight are they expected to be? Will they add a hypercone for mars landing?

    Regarding hypercones: most illustrations show them attached to the bottom of the lander, but I’m thinking it makes more sense to attach them to the top of the dragon (if needed at all) especially since the dragon already has a heat shield to cover what a hypercone might on the bottom. I would think this would help deployment, at mach, because the initial expansion is protected somewhat by the capsule.)

    Also, I’ve read that versions of the dragon may be of different sizes, not just different configurations.

  2. Al

    Interested in knowing if SpaceX actually has a Mars/Lunar -base- team.

    Not a “How can we get there” thing. But a “How do we live there?” team.

    1. Brock

      Bigelow would seem the more likely candidate for that. He would already have the necessary life support systems for long term stays developed for his space stations. In fact, if you could land one of his stations on end Moon’s surface, all you’d have to do is cover it in regolith for a ready-made shelter.

      1. Brock

        Just checked Wikipedia, and in fact Bigelow has already released a plan for a lunar base using his modules. So there you go.

      2. Vladislaw

        Bigelow stated that they are working on the problem of how to cover a module with regolith. Will be interesting the solution they come up with.

  3. George Turner

    Actually you can thrust straight down from the side of a cone with a device invented here, which I termed the butt flap. :D

    Just have the side-angled exhaust stream reflect of an extendable, slightly curved plate made out of refractory metal, much like an angled exhaust deflector under a launch pad. If the extended plate is held out with a linkage then it can even have it’s exact angle controlled to give stearing angles from a thruster that has a fixed mounting. The slight losses in the reflection should be more than made up for by the removal of the cosine losses.

    It should give almost the same performance gain as swinging the thruster outboard so it can aim vertically, but without the plumping nightmares. In concept it’s little different from redirecting horizontal jet exhaust downward on an F-35, or the maneuverable exhaust systems on fifth generation fighters.

    1. Al

      When you say “refractory metal”, “Tungsten” is the only key one that comes to mind. Do you have pointers to better refractory metals?

    2. Dean Kennedy

      Could you not get the same effect by making the pods more like a hawk-nose, extending the nostrils over the edge of the cone? If necessary, provide a protective PICA-X flap for use during ‘entry’ (as Rand prefers).

    3. George Turner

      Oh, I don’t think you’d need to go all the way to tungsten because the exhaust gas has already fully expanded, so it isn’t as hot. The bottom half of an F-1 engine nozzle (the nozzle extension) was just stainless steel, although it did have some film cooling from the turbopump exhaust. Unfortunately I don’t know the chamber pressure and expansion ratio of a Draco to calculate what the exhaust temperature would be.

      The hawk nose would also work, or really just a bent nozzle.

  4. George Turner

    Actually you can thrust straight down from the side of a cone with a device invented here, which I termed the butt flap. :D

    Just have the side-angled exhaust stream reflect off an extendable, slightly curved plate made out of refractory metal, much like an angled exhaust deflector under a launch pad. If the extended plate is held out with a linkage then it can even have it’s exact angle controlled to give stearing angles from a thruster that has a fixed mounting. The slight losses in the reflection should be more than made up for by the removal of the cosine losses.

    It should give almost the same performance gain as swinging the thruster outboard so it can aim vertically, but without the plumping nightmares. In concept it’s little different from redirecting horizontal jet exhaust downward on an F-35, or the maneuverable exhaust systems on fifth generation fighters.

  5. Curt Thomson

    That picture of the little girl with her iPhone is fantastic.
    (It looks like a little girl anyway)

  6. Coastal Ron

    Is it an optical illusion, or is the crew vehicle noticeably smaller than the cargo version?

    1. wodun

      Was just going to ask the same thing. Is it a scaled down prototype or will the Dragon Crew be smaller? The way things were covered during the last launch, we were lead to believe they would be the same size. Even astronauts were talking about how nice it would be to ride in such a spacious vehicle.

      This is sort of like the price creep for F9 launches. Turns out cargo deliveries are more expensive than satellites and crew more than either but this wasn’t exactly the ways things were portrayed in the media a year or so ago. Either bad reporting or good PR.

      1. Karl Hallowell

        This is sort of like the price creep for F9 launches. Turns out cargo deliveries are more expensive than satellites and crew more than either

        Of course it is. They have NASA for a customer and the destination is one of NASA’s prized gems. That’s going to drive up costs, especially if you’re carrying NASA astronauts as well. The price creep is well explained.

      2. Tom D

        Looks like a slightly scaled down model to me. Probably done to make it easier to work on, but a clear label is needed.

      3. Coastal Ron

        Turns out cargo deliveries are more expensive than satellites and crew more than either

        Why doesn’t that make sense to you? Cargo delivery requires a returnable capsule, whereas satellite launches don’t. That’s a big cost difference.

        For crew Musk has quoted $140M for up to seven passengers (versus the current $133M/flight for cargo), but crew capsules require extra equipment and engines for crew safety.

        I actually expect the cost of cargo delivery to fall on the next CRS contract, since SpaceX should be able to negotiate using used Dragons (each CRS flight under the current contract requires new vehicles).

        1. wodun

          It makes perfect sense that different services would have different prices but this is not how things were initially portrayed in the media. Like I said, either bad reporting or good PR.

      1. rickl

        That’s what I assumed at first, but when I looked at the pictures again, it really did look smaller. It doesn’t seem that much farther away.

        If you brought your tape measure with you, you could put this to rest. :)

        1. Rand Simberg Post author

          There are two factors. It’s farther away, but also, the closer, flown vehicle is on a display stand, making it appear taller. I’m quite confident that they’re the same scale.

          1. Coastal Ron

            I figured that since you were there it would be more apparent if there was a size difference. Glad there isn’t.

        2. Larry J

          I saw the same thing, but if you look at the cool picture of the girl taking a photo with her iPhone, it appears the old Dragon is mounted higher off the floor than the mockup.

    2. ken anthony

      The closer one is higher, two factors that make it look bigger. I’m sure they are the same size. Neither is a Red Dragon. That may be a larger version at least as far as the heat shield. My understanding is that a standard Dragon would crater before losing enough energy in the martian atmosphere.

      Also, the martian down mass may only be 2.5mt rather than the 10mt I’d read earlier. All subject to change before the actual mars landing whenever that might be.

      Can I get one of those for my backyard?

  7. reader

    OMG, looks like it is not fully reusable, they will need to overpaint the logo if they want to launch it again !

    1. rickl

      How come the COTS 2+ Dragon didn’t have a logo? The nose cap had a SpaceX logo, and the solar panel pontoons had Dragon logos, but they were all discarded during launch. Was that some sort of NASA requirement?

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