A Shift in Priorities - Sequel

Discussion in 'Alternate History Discussion: After 1900' started by rast, Apr 26, 2015.

  1. Dain Well-Known Member

    Joined:
    Aug 30, 2013
    The main drawback of solid fuel is that once it burns, there is no throttling down. It will burn at full blast until the fuel is exhausted. This makes them a liability both for safety reasons as well as useless for any mission profile that is more complicated than 'generate a lot of thrust quickly and in one go'.
    And even as launch boosters they are not optimal. Ideally larger spacecraft want to throttle down and back up again during the early phases of ascent to be able to safely and efficiently push through the period of maximum atmospheric stress on the vehicle. A purely solid fuel first stage doesn't have that option.

    As the bottom line concluded, this technology is stricly limited to putting payloads into simple orbits... or ballistic trajectories.
     
    Last edited: Sep 11, 2019 at 7:33 AM
    rast likes this.
  2. Tuna-Fish Well-Known Member

    Joined:
    Jun 1, 2013
    Sure it does:
    [​IMG]

    Also, solid rockets can be "turned off" by changing the nozzle configuration into something that does not produce net thrust, or by somehow reducing pressure inside the casing to a point where combustion stops. Most rockets that use SRBs do either or both. A really crude solution is to just blow up the nozzle -- without a nozzle with a throat, most SRBs don't do much in space.

    The big downside of SRBs is that everything must be pre-planned perfectly, and if anything unexpected happens, your only option is pretty much to keep following the plan, regardless of if it makes any sense anymore.

    The current champion of the "look how solid my propulsion is" cup is LADEE, a probe that went to the moon on top of a 5-stage solid fuel rocket. The cross-section of each stage was fine-tuned to match the requirements, and after the final solid stage was exhausted there was iirc less than 1 m/s of error in the velocity in the rocket.

    For any useful satellites, you of course still need some kind of liquid-fueled attitude control system, but those and booster rocket engines are very different beasts. I can see a solid+monopropellant system working as a moon architecture, although the stack would mass a lot more on the pad than cryogenic liquid propellant version.
     
    Pera and rast like this.
  3. rast Well-Known Member

    Joined:
    Aug 22, 2008
    Society has no business to permit degenerates to reproduce their kind.
    (Theodore Roosevelt)

    There was no doubt: she was pregnant. That was slashing, really. But, good grief, she was thirty-eight today. Would it turn out well? Makambo was as proud as he should be. Yet, the bloke was – of course – looking forward to sire more kids. Should she survive childbirth, she was due for the next pregnancy… It was going to kill her, rather sooner than later. Medical care in this country was a joke.

    Yeah, it was a big problem indeed. Many women hereabouts were pregnant. But there were no midwives and no gynaecologists. – The expectant mothers were no primitive savages who might manage without medical support; they all had been born and raised in the USA; they needed doctors and nurses… One was heading for a debacle. She had enquired: the survival rate was one in three. Only one third of those women who had already given birth were still alive…

    It had been clear from the start that this society was bound to shrink. With – on average – only one woman available for every ten men, shrinkage was inevitable. But with two out of three women not surviving pregnancy and childbirth, extermination was threatening. Something had to be done. Anne Robbins was determined to achieve an improvement.

    Queen Vera was pregnant too. However, she had at her disposal the only professional physician found in this godforsaken country. – Big Chief Amagasfano should nevertheless be able to perceive the quandary. One couldn’t plough ahead as hitherto. One had to ask the Germans for help. They were guarding the islands; one ought to be able to contact them.

    She had already started to bludgeon Makambo. He was the one to propose to Amagasfano. – The trouble was that Makambo hated Amagasfano. Asking the man for a favour would cause him pain. But it wasn’t a favour; it was a dire necessity…
     
  4. rast Well-Known Member

    Joined:
    Aug 22, 2008
    The art of government is to make two-thirds of a nation pay all it possibly can pay for the benefit of the other third.
    (Voltaire)

    Field Marshal Dang Gangjun loved those displays. It had been hard work to train his staff to do them correctly. They had to show the reality, nothing but the reality; sugarcoated information was useless. And it wasn’t his staff alone; all subordinate staffs had had to be taught to stick to strict truth as well. Accurate reporting was essential. – Now, he could review the strength of his forces every morning – and be sure it was the real thing he was looking at.

    Yes, it was an impressive array. Men and machines under his command were truly numerous. And the equipment was quite good. Much of it was made in the US – to Dang’s displeasure, but nevertheless of excellent quality. Morale of the troops was outstanding. A pity there was no war pending at the moment… Well, the Russians weren’t forgotten; there still was a score to be settled with them.

    Right now, the point was moot anyway. The Great Qing Empire had been ruffled, yet ancient China had survived fairly intact. Běijīng and Shanghai had been rebuilt – to a certain extent. The rest had to be left to private initiative. The outlying provinces in the north were still waste, but they had never been part of the Middle Kingdom of old. There truly was no need for self-deprecating.

    One was the Asian hegemon, no ifs, no buts. Hence one ought to perform accordingly. Dang couldn’t abnegate that he felt a certain sympathy for Chiang Zhongzheng. The man had known how to wield China’s power. Kicking out all aliens had been a masterpiece. And the aliens had lumped it. Because Chiang’s power had been obvious to all. – In fact, relative to the population count, Dang’s displays were clearly showing that Chiang’s armed forces had been smaller than his, Dang’s, were today.

    But the Little Man from Sichuan was insisting that China should continue to eat humble pie. Dang didn’t like it. It was unnatural. The Middle Kingdom was the centre of the world. Deng’s gibberish about the economy was blatant rubbish. – Should he really tolerate these shenanigans?
     
    Last edited: Sep 13, 2019 at 4:43 AM