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New Concept - ITS Workhorse

Discussion in 'SpaceX' started by sjoshuaj, Apr 15, 2017.

  1. sjoshuaj

    sjoshuaj Member

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    An idea to replace the Falcon 9 and Falcon 9 Heavy and bring full reusability to satellite launches, ISS cargo / people deliveries and so much more. =-)
     

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  2. Grendal

    Grendal Active Member

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    Interesting idea. I'm sure it's one that SpaceX people have considered. Implementation of such a thing would be to have a real customer have demand for it. With ITS, for now, the customer is SpaceX and their plans to colonize Mars. So they are building the vehicle to their specification and needs for their endeavor. The Space Shuttle had the US Government and others with the task of building the ISS. Let's say the government decides to replace the ISS with something else and they need a super heavy lifter to do it then there would be a customer for your idea. Or, they see the ITS booster and second stage in action and design something to work within its parameters that they want to put up there. For now though, nothing exists or is on paper that would need such a vehicle. It is common for designers to plan their designs around the abilities of the transport vehicle. So if SpaceX has clear indication of a vehicle being built then I could see a customer showing up to take advantage of the new platform.
     
  3. sjoshuaj

    sjoshuaj Member

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    According to SpaceX’s own data the ITS booster can launch for 11 million and the ITS Tanker, their reusable second stage, can launch for 8 million. Let’s assume the cost of what I’m proposing for the second stage is more expensive per launch at say 16 million. That’s still only 27 million per launch. This is less than half the price of a falcon 9 launch at 62 million and under two thirds the price of a falcon heavy launch at 90 million. Even when you take into account future reusability the falcon 9 and falcon heavy will continue to be more expensive because in both cases their second stage is not reusable(and probably never will be). The numbers get even more compelling when you consider that with what I’m proposing you can deliver multiple large payloads at the same time vs. one with the F-9 and F-Heavy.

    SpaceX loves to save money by testing out their experimental hardware on customer paid launches. Why not continue that tradition by first creating what I'm proposing, make the ITS booster and ITS "Workhorse" first for paid LEO and GTO customers and then use that knowledge and sunk R&D to create the ITS Tanker and ITS Spaceship for their future mars missions.

    But, like you said, they may have already considered this course of action. Only time will tell.
     
  4. jkn

    jkn Member

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    Developing reusable second stage will not be easy. Probably they will have many failures, before success. If 2. stage delivers satellite to orbit and then fails to land, there are no large losses.

    It is not a good idea to transport satellites as a cargo with crew. Rocket fuel makes very large explosion.
     
  5. Ludus

    Ludus Member

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    #5 Ludus, Apr 28, 2017
    Last edited: Apr 28, 2017
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  6. ecarfan

    ecarfan Well-Known Member

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    I am halfway through reading that Purdue Engineering paper. I am not an aeronautical engineer and cannot properly evaluate their calculations. But from a layperson's perspective, I am not yet convinced that their cycler concept is superior to what SpaceX has proposed with the ITS. Their cycler concept seems far more complex; it requires the cycler vehicle to be assembled in orbit, a greater variety of vehicles built, and a lot of transfers of people between vehicles while in orbit around Earth and Mar. The SpaceX plan is much simpler. Of course the ITS plan is still incredibly challenging. Clearly Elon does not believe the cycler concept is the best approach.

    Reading the Purdue paper I am amazed at the number of typos and poorly constructed sentences. Apparently they are not aware of the desirability of having someone proofread it.
     
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  7. dkemme

    dkemme Member

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    I'm struggling understanding the cyclers orbits, two times around earth for every time to mars, will this require a lot of fuel?

    Fig. 5.2.1.2.1
     
  8. Grendal

    Grendal Active Member

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    Elon definitely knows the cycler concept. It's what is used in "The Martian" book and movie. He and his team of experts must have done a lot of thinking about what their Mars colonization strategy would be and judged their system as superior to the cycler system. It makes sense too. SpaceX is creating the concept of reuse that has never existed before. Reuse is what makes ITS work. If you didn't have it then the cycler system would probably be a better strategy. I'm pretty sure that SpaceX went with ITS because of the amount of people and payload they want to be transferring as well. The cycler is fine for small numbers of people and tiny payloads. Elon probably told his team he wanted to move 1 million pounds at a time. With that number you get ITS.
     
  9. ecarfan

    ecarfan Well-Known Member

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    That is my non-expert view as well. But somehow the Purdue University engineering student project came to a different conclusion. And they assumed a lot of vehicle reuse. See https://engineering.purdue.edu/AAECourses/aae450/2017/spring/docs/AAE%20450-Project%20Destiny.pdf . I'm only partway through their analysis, and much of it is over my head, but if I had to bet I would put my money not the SpaceX approach. I'm not terribly worried that Elon's team is going down the wrong path!
     
  10. jkn

    jkn Member

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    Travel between Earth and Mars does not consume any fuel! Changing speed does. First accelerate from Earth to transfer orbit then from transfer orbit to Mars. Cycler stays in transfer orbit, so it does not use fuel except for steering. Finding a transfer orbit that is in sync with Earth and Mars is difficult.

    I don't know why Elon dislikes cycler. It does not change speed, so it can have heavy radiation shield. So travelers avoid a lot of radiation.
     

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