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An astronaut explains how it'd feel to ride Elon Musk's giant spaceship

Discussion in 'SpaceX' started by ecarfan, Oct 11, 2017.

  1. ecarfan

    ecarfan Well-Known Member

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    See An astronaut explains how it'd feel to ride Elon Musk's giant spaceship from LA to New York in 25 minutes

    An astronaut explains how it'd feel to ride Elon Musk's giant spaceship from LA to New York in 25 minutes

    Quote: "Launch, insertion, and entry would be similar to a capsule spacecraft" — like the Soyuz — "with the difference being in the final phase of landing," Chiao said. "During launch on a rocket with liquid engines ... the liftoff is very smooth, and one really can't feel it... "Ignition of the next stage engine(s) causes a momentary bump in G-force," he said. "As you get to the last part of ascent, you feel some G's come on through your chest, but it is not uncomfortable." When the spaceship's engines cut off, though, Chiao said you'd become "instantly weightless" as you temporarily coasted through space. "You feel like you are tumbling, as your balance system struggles to make sense of what is happening, and you are very dizzy,"... this can cause nausea.".. "As you start to re-enter the atmosphere, you would feel the G's come on smoothly and start to build," Chiao said. As the spaceship nosed up and down to shed speed, he added, you'd at points feel about 5 G's, which would make you feel roughly five times as heavy. As the spaceship sped toward the ground, its engines would fire to land it on a floating barge. "You would both feel and hear" the engines, Chiao said. "As the thrust builds, you would feel the G's come on again, and then at touchdown, you would feel a little bump."
     
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  2. e-FTW

    e-FTW New electron smell

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    Great stuff there. Cannot help but feel that this is definitely what an astronaut expects, and is used to. A "normal" might describe this in different terms. Can't feel the launch? Hmm, ok.
    Who here has felt 5 Gs? :)
     
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  3. Grendal

    Grendal Active Member

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    If you own a P100DL then it's practically a daily experience. :p
     
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  4. BluestarE3

    BluestarE3 Active Member

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    SpaceX may need to work with sister company Tesla to develop some bio-weapon defense barf bags so that if one novice astronaut gets motion sickness, the smell is well-contained so fellow passengers don't succumb to the same fate due to olfactory triggers... as seen here:

     
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  5. ecarfan

    ecarfan Well-Known Member

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    I doubt if anyone on TMC has ever felt anything even close to 5Gs unless their are some astronauts amongst us who have been to orbit.

    I thought the quotes from Chiao were interesting because it was the first time I had read commentary about the E2E BFR concept from someone who had actual experience with the forces involved. I was also intrigued by his statement that liquid-fueled rockets don't produce high G forces at liftoff. Re-entry forces however will be significant.

    I am looking forward to my BFR flight a decade from now. :D
     
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  6. dhanson865

    dhanson865 Active Member

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    BFR has about 5:4 Thrust to weight ratio if max loaded at launch near sea level, meaning you'd feel just over 1G to start. The G force at launch would be minimal and would build slowly. You get to higher Gs but I think he is saying it comes on gradual enough it wouldn't scare the average person.

    If they didn't load it to weight capacity, it'd still be nothing extreme at launch. Can't reduce the fuel beyond what's needed to get there so the minimal weight for one person is still going to be enough to keep TTW reasonable at takeoff maybe starting at 1.5G if you were the only passenger.
     
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  7. Etna

    Etna Member

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    I did 9Gs in an F-16 once. :)

    And I promptly got sick afterward. 9Gs for three or four seconds were *painful*, but longer 4-5Gs loops were fun. Actually 5Gs is nothing exceptional for aerobatic pilots, even civilian ones.

    I suspect BFR passengers will be sitting with the head not much higher than the rest of the body, that makes g-tolerance much easier.

    For a suborbital flight, I am not sure there is a real need to go to 5 Gs. If that proves to be too high they can tailor the flight profile to lower Gs. My guess 3Gs would still provide a practical flight profile.
     
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  8. N5329K

    N5329K Member

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    #8 N5329K, Oct 11, 2017
    Last edited: Oct 11, 2017
    I have hit 5 G's (and a bit more) flying aerobatics. A person in reasonable shape and prepared would definitely feel the "weight" but would not pass out. Other people, though, certainly could (some folks get lightheaded just standing up). And if you made the poor decision to reach down for something exactly when the G-s hit, you might well injure your neck muscles, or worse.
    Lawyers are gonna love this.
    Robin
     
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  9. skitown

    skitown Supporting Member

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    For comparison, I had to search for the highest g-force rollercoaster. Not an inspiring name for a rocket however. :)

    "Maximum G-Force: Tower of Terror – Gold Reef City, South Africa
    Have you ever wondered what it would feel like to launch into the atmosphere on a space shuttle? Gold Reef City’s Tower of Terror coaster may help give you a better idea. Tower of Terror holds the record for most G-force on any roller coaster in the world, an intense 6.3G. This is nearly twice the amount that the average astronaut experiences when making their way through the atmosphere. The difference here is that the force is only sustained for a matter of seconds rather than several minutes, which makes it manageable for the average roller coaster rider. The Tower of Terror is one of many thrill rides developed by the renowned designer, Ronald A. Bussink."

    Top 7 Most Thrilling Roller Coasters in the World - Entertainment Designer
     
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  10. larmor

    larmor Active Member

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    Or you could sit in your business/economy seat for 18 hours...
     
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  11. skitown

    skitown Supporting Member

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    ...trying to prevent leg clots. :eek:
     
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  12. dhanson865

    dhanson865 Active Member

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    again, it's a simple parabolic flight, the Gs don't hit, they gradually phase in. Takeoff is just over 1G, there is no sudden jump from 1G to 2G or 2G to 3G, just a gradual acceleration of acceleration as fuel leaves out the bottom of the rocket until just before MaxQ when they throttle back( not to zero thrust, just less than max) and after MaxQ they gently increase thrust again or not. Nothing is forced about how abrupt the G forces change. It'll be a one move ballet in slow motion( ground and air speed will be fast but motion changing angle compared to gravity will be gradual).
     
  13. N5329K

    N5329K Member

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    Gradual is definitely easier on the system. "Crisp" is hard on it. I have always been partial to big, slow 1 G positive maneuvers, even when upside down. BTW, the Blue Angels fly pretty aggressively and they pull a lot of "crisp" G. This is why barf bags are tucked into the cockpit when distinguished visitors or media go along for the ride.
    They call the bags Boarding Passes.
    Still and all, 5 G's is 5 G's, and if the astronaut's analysis is correct (and I have no reason to think it isn't), those 30-minute suborbital hops would be pretty exciting in good - and not so good- ways.
    Robin
     
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  14. dhanson865

    dhanson865 Active Member

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    #14 dhanson865, Oct 11, 2017
    Last edited: Oct 11, 2017
    Let me ask you this, when is the last time the Blue Angels did a move that the first half took 10+ minutes to complete and was basically flying nearly straight, then make a minor change that would provoke a "that's all you did?" response, before completing the maneuver with another 10+ minute segment of flying the shortest path to land.

    It'll be exciting as all get out to ride but show someone the path or live stream the flight and it's a pretty simple path to follow with no surprises. On the crisp vs smooth scale this would have to be smoother than any "trick" or even simple display move a Blue Angel ever does.

    And I say all of that as someone who watches every SpaceX launch at least once, and sometimes more than once. I still fast forward through the coast phases...
     
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  15. ccutrer

    ccutrer Active Member

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  16. e-FTW

    e-FTW New electron smell

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    Would that be because SRBs can't be throttled? So they go to 10% right away?

    Overall, am thinking vibrations might also be quite a change from commercial flights. And if the G-loads are not that bad and progressive, am sure one can get used to it.
     
  17. TaoJones

    TaoJones Beyond Driven

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    In the spirit of recycling, there's an opportunity here for "Powered by barf" t-shirts and other merchandise.

    Hey, if a garbage disposal and/or food processor worked back in the day...
     
  18. N5329K

    N5329K Member

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    Let me ask you this, when is the last time the Blue Angels did a move that the first half took 10+ minutes to complete and was basically flying nearly straight, then make a minor change that would provoke a "that's all you did?" response, before completing the maneuver with another 10+ minute segment of flying the shortest path to land.
    The last time they cleared the Karman Line?
    Robin
     
  19. Mike1080i

    Mike1080i Member

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    Actually SRB's can have a form of throttling (and the STS SRBs did). But that may get a bit off topic.

    The key is thrust to weight ratio, which constantly changes during the ride up hill as propellant burns and the vehicle gets lighter. As I recall the Shuttle system was designed to peak at 3Gs, which most anyone in good health could handle. Once you reach the desired peak G level then you throttle to maintain that. I think most people won't have a problem with the ride up hill, but the sudden drop off to microgravity after MECO might have them reaching for the bags.
     
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  20. e-FTW

    e-FTW New electron smell

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    Cool, thanks. Obviously, I meant 100% there.
    I do wonder what he meant though about liquid fueled being an easier ride on take-off.
     

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