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Lukaszenko

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Posts posted by Lukaszenko

  1. 12 minutes ago, Jaff said:

     

    No doubt but they’ve learnt from that and have had many successes since. And like I said orevioudlybthe idea is these are just 3 F9’s 

    Indeed no doubt they learned from THAT. Undoubtedly, one of the things they learned is that there are many more "thats" which they don't know about, and every time you change something, and even if you don't, those "thats" can creep up on you.

    Remember, there are millions of things that can happen to a rocket, and only one of them is good. 

  2. 11 minutes ago, GoSlash27 said:

    I'm curious as to why they chose the exact same 2nd stage engine for the Heavy as they use in the 9. An engine that circs 25 tonnes is also capable of 70 tonnes? If that's the case, isn't that engine kind of overkill for the Falcon 9?

    Best,
    -Slashy

    So that they don't have to develop/ tool/ build/ support a completely different engine for what is used in 10% (or, in this case, 3%) of the rocket.

    Commonality of parts is a big theme at Space X, because it creates huge cost and headache savings. It's at the cost of a bit of payload, but apparently that is something they can spare. 

  3. Your orbit would degrade and you would sink into the lower atmosphere (or at least parts of you). The problem is that once you hit enough atmosphere, your trajectory quickly degrades and puts you into a steep path to the denser parts...but, much steeper and hence quicker than you want to give you enough time to shed your speed and heat. The result is that you DON'T shed enough speed and heat and you either burn up or break up, or some combination of both. 

  4. It highlights the fact that it IS used, they are confident that it will fly, and they plan to do it again. Often, quickly, and cheaply. 

    Such that they don't even bother cleaning it. 

    You know when you go check out a  used car and it's been so well cleaned that it's suspicious? I think it's kind of like that.

  5. 4 hours ago, Green Baron said:

    Simple answer: no. (Edit: or you're cheating with the engine)

    It is theoretically possible, because the wind can contain more than enough energy that  the craft needs to travel at or above its speed.  Practically harnessing that energy is a different matter...

    ...but also possible, and by purely mechanical means:

    https://en.wikipedia.org/wiki/Blackbird_(land_yacht)

    Image result for blackbird wind

     

  6. I find that if you want the most delta-v efficient vehicle, a LOT of TWR is good, with the limiting factor generally being 1) can you fit enough engines 2) can the craft handle the heating. Gravity losses are generally much greater than aero losses. 

    My best EVE ascent vehicle, for example, has something between 2/3:1 TWR on the first stage, if I remember correctly. Any less and it wouldn't perform as well, despite the large dead-weight reduction and theoretically higher delta-v. 

    Untitled_1.jpg

     

  7. 10 hours ago, sevenperforce said:

    ....this means the horizontal component of velocity is roughly 1.27 km/s. However, Cape Canaveral is comoving underneath at a nice steady clip of 409 m/s, meaning that the Falcon 9 first stage only needs to kill about 860 m/s of downrange velocity to essentially "stop". 

    You lost me...how/ why is the cape moving slower than the rocket? 

  8. 48 minutes ago, KSK said:

    From the video, speed at MECO is 5877 km/hour or 1.63 Km/s. I'm not sure how much delta-V the boostback burn does impart but I think your estimate is probably a bit high. A 1.5 km/s burn would be nearly enough to stop the whole stage dead in mid air!

    I crudely timed how fast the altitude was changing, which gave me the vertical component. From this I figured out the horizontal (~1.1 km/s). In order to kill the horizontal and then hope to make it back, I guessed ~1.5 km/s would suffice. 

  9. I still don't understand exactly what kind of trajectory the rocket flies and how it turns around to the launch site, even after watching the entire video from start to finish. How far down-range does it actually go before turning around?

    The speed indicator doesn't seem to help. How much delta-v does the boost-back burn actually take up? It's still going thousands of km/h after the burn, but apparently the other way?

     

    Edit: I did some rough calculations, and I'm guessing it needs 1-1.5 km/s delta-v. Still, would be nice to get more detailed data regarding the velocity vectors and distance.

  10. 1 hour ago, Steel said:

    Or, if we assume this was done by professional engineers rather than monkeys, maybe it could suggest that they've extensively simulated and tested these new grid fins and have updated the software with new parameters? :P

    Undoubtedly. But there's no way in hell that's the full story. My point is that it works on a closed-loop feedback control. It moves the grid fins, checks how the rocket reacts, and then moves them some more until the rocket reacts the way that it should.

    Okay, so it's a bit obvious now that I said it, but it's just something I never thought about :rolleyes:

     

  11. 5 hours ago, sevenperforce said:

    Whoa, really freaking cool:

    34707526913_a9498956db_o_kindlephoto-164

    The new Block V titanium grid fins are curved. They're also substantially larger than the original aluminum ones.

    Interesting. I thought that the computer would know more or less how the rocket will react when it tilts and twists the grid fins. But, here it looks like they just came in and slapped on some bigger & curvier fins and they still expect the rocket to return no problem. I guess it implies that the computer basically learns how to control the rocket on the fly. It makes sense; so many variables are always changing. I wonder if, for example, half a grid fin got ripped off, would the computer be able to adjust for it?

  12. On 6/2/2017 at 9:33 AM, Lukaszenko said:

    Dammit, next launch is smack in the middle of my party time. I can postpone work or sleep, but Saturday evening?

    Maybe I'll just host a launch party.... 

    So yeah, smack in the middle of my party, I just switched the TV to SpaceX launch and turned off the music. I was a bit made fun of, but in the end it was a big hit. I don't care whotf you are, it's an interesting thing to watch.

    Funnily, after the first stage landed, I turned it off and switched back the music. I guess the fun part was over :D

     

  13. Did anybody else see this article? Apparently they want to build many An-225s and use them as launch vehicles. 

    Kind of cool. I guess. But, did they get their math REALLY wrong? "90% of the energy of the launch vehicle is spent getting up to an altitude of 10km"? Even my friend who knows NOTHING about spaceflight was dubious about this, if for no other reason than that satellites fly MUCH higher than 10 km (disregarding any sideways velocity). He's actually the one that asked about this. Anyway, it's not him that's going to throw down billions to make this happen, so he didn't really care that much.

    And what? They wanted to use the An-225 to launch a fully loaded Buran & Energia from this plane's back? Eh? 

    I know it can lift a lot, but 2.5 million kg is a bit more than a lot.

    Anyway, normally I wouldn't care about stuff like this, but this is a legitimate article about a legitimate thing from a legitimate source. Really made me go like this :huh: 

    http://www.bbc.com/future/story/20170503-the-worlds-biggest-plane-may-have-a-new-mission

    p051tp9b.jpg

     

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