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I think now that they have proven they can 'hit the hole', almost spot on, they'll be able to get approval to go for a try on cleared land space. It sounds lik

I think now that they have proven they can 'hit the hole', almost spot on, they'll be able to get approval to go for a try on cleared land space. It sounds like to me, landing on land would be ideal; less expensive and less risk with stabilization and rough waters.

harshreality 12y ago
They need to be able to stabilize the rocket's landing in all sorts of conditions if they want to have any hope of landing it on another planet. It's not like interplanetary launches will be able to schedule launches to choose optimal weather conditions for the landing. Maybe, if they're lucky, they'll be able to orbit briefly to avoid bad weather at the landing site, but moderate winds and wind gusts are going to be a problem. If it's impossible to reliably land under those conditions, the whole idea is flawed for the purposes of interplanetary flight. You can't have rockets going to Mars, and only have 50% or 75% surviving for relaunch. That's not the kind of cost reduction that will make interplanetary travel and resupply feasible. It would obviously help with LEO launch costs, though, or any return landings on Earth. Even if rocket stages are only recovered some of the time, and not reliably, that's a significant cost savings and well worth doing. It's just that Musk is so intent on interplanetary travel driving all this technology. If it's only for cost savings for Earth landings, a parachute system or a specially designed (more accommodating) landing complex/barge could work too, right? > (paraphrasing multiple comments) "but this is to re-land rocket stages on Earth" Here's an interview where he specifically talks about his long term goal of landing rocket stages on other planets. He says parachutes negatively affect reusability, I'm not sure how much of that is potential damage or off-site landing and how much is the necessity to reinstall a parachute for the next launch. The point here is that he is clearly not thinking only of Earth landings in developing this technology. I think some sort of assisted landing or more developed landing site could increase chance of recovery and reusability for Earth landings, decreasing total launch costs for Earth orbit missions, at the cost of not being applicable to landings on other planets. [1] https://www.youtube.com/watch?v=SOpmaLY9XdI?t=11m30s https://www.youtube.com/watch?v=SOpmaLY9XdI?t=11m30s
- gfodor 12y ago
  At the same time, getting to a point where SpaceX has a 10X pricing advantage over there competitors could have a nice effect on their R&D budget for solving problems that may not be immediately applicable on Earth.
- daeken 12y ago
  > They need to be able to stabilize the rocket's landing in all sorts of conditions if they want to have any hope of landing it on another planet. Well, not really. Dragons (and Red Dragons, for interplanetary travel) are way, way less sensitive to the whims of weather. The issue with the first stage is that you have a very large, very fragile, very bottom-heavy tin can that you're trying to balance on a moving platform. This is entirely different than trying to land a pod, which is what we'll be doing on other planets. Dragon v2 will be landing on land (though doing parachute recovery from water for initial CCS missions, as per NASA spec), and we'll see how stable it is then.
  - deleted 12y ago
    [deleted]
    - segacontroller 12y ago
      OK that may be the long term goal, but what is the short term goal? What is the goal of landing this rocket stage on earth? Is it to use this model to land on another planet, or is it to use this model to reduce costs and reuse the first stage of the rocket?
      - deleted 12y ago
        [deleted]
      - _broody 12y ago
        It's the later. Every other possible use of the technology is just speculation at this point.
      - TeMPOraL 12y ago
anigbrowl 12y ago
Landing is an awful lot harder than taking off, it seems to me; a single engine rocket with stabilizing jets is a bit like trying to land a pogo stick - possible, but inherently problematic. I know this must seem stupidly obvious, but I wonder if a better design for a reusable launch vehicle isn't 4 engines connected by a frame with the payload in the center, basically a chair. Yeah, it sounds horribly unwieldy with a bunch of structural challenges, but the thing is it's self-stable in a way that a vertical column can never be. A few years ago the wisdom was that small (remote control) helicopters could only be flown stably with a coaxial main rotor. Quadcopters would work in theory, but everyone figured 4 motors on an frame was going to be even more complex to mange and that the stresses on the frame would likely weaken it too much, the power-to-weight ratios wouldn't work out and so on and so on. Now everyone is using quadcopter configurations because they are much easier to control and not actually that difficult to build. My naive opinion is that output has never quite been consistent enough from rocket to rocket to make the idea of bolting multiple rockets together seem worthwhile unless they were all part of a single fuselage; one of the four would always be putting out too much or too little power and the whole contraption would fly off course in short order. but since the SpaceX rockets depend on liquid rather than solid propellant, and very precise pumping is not that big of an engineering challenge these days, it seems like it should be worth experimenting with on a small scale.
- classicsnoot 12y ago
  quadcopters I am not an aerodynamics person, but as far as i understand the 4-8 rotor configuration works because of how light the involved tech is/has become. In terms of payload, quads flat out suck. Yes, they are getting better, but currently they cannot haul. I realize we are talking about explosive thrust versus turbine generated thrust, but that alone makes me think this configuration [4 rocket chair] is unfeasible. Just my .02$.
- lmm 12y ago
  AIUI rockets are tall and thin to reduce the aerodynamic stress on them while they're accelerating. It's not about being worried about them flying apart per se. The Falcon already has 9 engines at the bottom, but they're clustered closely together to fit under a narrow fuselage.

harshreality 12y ago

They need to be able to stabilize the rocket's landing in all sorts of conditions if they want to have any hope of landing it on another planet. It's not like interplanetary launches will be able to schedule launches to choose optimal weather conditions for the landing. Maybe, if they're lucky, they'll be able to orbit briefly to avoid bad weather at the landing site, but moderate winds and wind gusts are going to be a problem. If it's impossible to reliably land under those conditions, the whole idea is flawed for the purposes of interplanetary flight. You can't have rockets going to Mars, and only have 50% or 75% surviving for relaunch. That's not the kind of cost reduction that will make interplanetary travel and resupply feasible. It would obviously help with LEO launch costs, though, or any return landings on Earth. Even if rocket stages are only recovered some of the time, and not reliably, that's a significant cost savings and well worth doing. It's just that Musk is so intent on interplanetary travel driving all this technology. If it's only for cost savings for Earth landings, a parachute system or a specially designed (more accommodating) landing complex/barge could work too, right? > (paraphrasing multiple comments) "but this is to re-land rocket stages on Earth" Here's an interview where he specifically talks about his long term goal of landing rocket stages on other planets. He says parachutes negatively affect reusability, I'm not sure how much of that is potential damage or off-site landing and how much is the necessity to reinstall a parachute for the next launch. The point here is that he is clearly not thinking only of Earth landings in developing this technology. I think some sort of assisted landing or more developed landing site could increase chance of recovery and reusability for Earth landings, decreasing total launch costs for Earth orbit missions, at the cost of not being applicable to landings on other planets. [1] https://www.youtube.com/watch?v=SOpmaLY9XdI?t=11m30s https://www.youtube.com/watch?v=SOpmaLY9XdI?t=11m30s

gfodor 12y ago
At the same time, getting to a point where SpaceX has a 10X pricing advantage over there competitors could have a nice effect on their R&D budget for solving problems that may not be immediately applicable on Earth.
daeken 12y ago
> They need to be able to stabilize the rocket's landing in all sorts of conditions if they want to have any hope of landing it on another planet. Well, not really. Dragons (and Red Dragons, for interplanetary travel) are way, way less sensitive to the whims of weather. The issue with the first stage is that you have a very large, very fragile, very bottom-heavy tin can that you're trying to balance on a moving platform. This is entirely different than trying to land a pod, which is what we'll be doing on other planets. Dragon v2 will be landing on land (though doing parachute recovery from water for initial CCS missions, as per NASA spec), and we'll see how stable it is then.
- deleted 12y ago
  [deleted]
  - segacontroller 12y ago
    OK that may be the long term goal, but what is the short term goal? What is the goal of landing this rocket stage on earth? Is it to use this model to land on another planet, or is it to use this model to reduce costs and reuse the first stage of the rocket?
    - deleted 12y ago
      [deleted]
    - _broody 12y ago
      It's the later. Every other possible use of the technology is just speculation at this point.
    - TeMPOraL 12y ago

anigbrowl 12y ago

Landing is an awful lot harder than taking off, it seems to me; a single engine rocket with stabilizing jets is a bit like trying to land a pogo stick - possible, but inherently problematic. I know this must seem stupidly obvious, but I wonder if a better design for a reusable launch vehicle isn't 4 engines connected by a frame with the payload in the center, basically a chair. Yeah, it sounds horribly unwieldy with a bunch of structural challenges, but the thing is it's self-stable in a way that a vertical column can never be. A few years ago the wisdom was that small (remote control) helicopters could only be flown stably with a coaxial main rotor. Quadcopters would work in theory, but everyone figured 4 motors on an frame was going to be even more complex to mange and that the stresses on the frame would likely weaken it too much, the power-to-weight ratios wouldn't work out and so on and so on. Now everyone is using quadcopter configurations because they are much easier to control and not actually that difficult to build. My naive opinion is that output has never quite been consistent enough from rocket to rocket to make the idea of bolting multiple rockets together seem worthwhile unless they were all part of a single fuselage; one of the four would always be putting out too much or too little power and the whole contraption would fly off course in short order. but since the SpaceX rockets depend on liquid rather than solid propellant, and very precise pumping is not that big of an engineering challenge these days, it seems like it should be worth experimenting with on a small scale.

classicsnoot 12y ago
quadcopters I am not an aerodynamics person, but as far as i understand the 4-8 rotor configuration works because of how light the involved tech is/has become. In terms of payload, quads flat out suck. Yes, they are getting better, but currently they cannot haul. I realize we are talking about explosive thrust versus turbine generated thrust, but that alone makes me think this configuration [4 rocket chair] is unfeasible. Just my .02$.
lmm 12y ago
AIUI rockets are tall and thin to reduce the aerodynamic stress on them while they're accelerating. It's not about being worried about them flying apart per se. The Falcon already has 9 engines at the bottom, but they're clustered closely together to fit under a narrow fuselage.