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Sturgeon's House

LostCosmonaut

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Everything posted by LostCosmonaut

  1. WoT v WT effort-thread

    Played a bit of Wehr Thunder. The Flakpanzer I with mixed HVAP/API belts is hilarious.
  2. Sports meets politics; https://www.si.com/extra-mustard/2018/01/16/donald-trump-height-weight-tim-tebow-mike-trout Not to get all tinfoil hat, but Trump does look pretty chunky.
  3. I Learned Something Today

    This thread is intended to be a place for cool things that you just found out about, but that aren't necessarily major enough to merit their own thread. For instance, today I learned why heavy water is/was used as a moderator in certain types of reactors. Since hydrogen atoms are small, they are very good at slowing down neutrons, but regular hydrogen also has a nasty tendency to absorb said neutrons (which you probably want to be absorbed by the uranium/plutonium in your reactor). Deuterium is a bit heavier, but still pretty damn good at slowing neutrons, and it's much less likely to absorb them.
  4. Aerospace Pictures and Art Thread

    Post cool pictures (including art) of aerospace object here.
  5. This thread is for discussion of modern (including Cold War) tank destroyer and gun carrier concepts. Most of these feature a good sized gun on a relatively light chassis with good mobility (as a result, they are sometimes known as light tanks). Some are built on converted IFV chassis. Examples include;
  6. The Space Exploration Achievements Thread

    Forbes is such trash; https://www.forbes.com/sites/lorenthompson/2018/01/15/doubts-about-spacex-reliability-persist-as-astronaut-missions-approach/#345d36653305 Concern trolling about the Zuma launch written by somebody whose "think tank" receives funding from Lockheed and Boeing (aka ULA).
  7. WoT v WT effort-thread

    Anybody here still play Worst of Tanks?
  8. Comparison of Rocket Payload Fractions

    I have compiled some data on the payload fraction (payload to LEO / Gross mass) of various rocket systems; From this, several thing can be seen; Solid rocket boosters utterly ruin your payload fraction. Despite having a significantly higher specific impulse than other engines (365 seconds for the RS-68 vs. 285 seconds for the RD-275), hydrogen-fueled launch systems only have a slightly better payload fraction than hypergolic systems, or are even significantly worse. Larger rockets generally have a larger payload fraction (Saturn I vs. Saturn V, Falcon 9 vs. Falcon Heavy). Titan II and Titan IV are not entirely comparable. STS is a stupid pile of trash. Kerolox first stage provide significantly better payload fractions in almost all cases, while avoiding the difficulties associated with liquid hydrogen. Hypergolics generally have inferior performance to both, but are significantly easier to handle, and the difference is not extreme. Data via wiki, except where noted (the gross weights for Delta IV Heavy and Atlas V 551 were horribly off, especially for the latter). Encylopedia Astronautica data mostly agreed, but that site is severely lacking in info on the Falcon family. @Sturgeon@Collimatrix@T___A
  9. Comparison of Rocket Payload Fractions

    For whatever reason Encylopedia Astronautica and wiki give the Ariane 1 a lower value for payload to LEO vs. GTO (1400 vs. 1850), which is highly odd. I can't think of any reason why that would be the case (GTO requires much more delta v than LEO). Going by the payload fraction to GTO, I get 1850/207200 = .0089, vs. 6300/705000 = .0089 for Proton-M, and 14220/738960 = .0192 for Delta IV Heavy. I think this is explainable by Ariane 1 being an older rocket with somewhat less efficient engines (the Viking-2s on Ariane 1 have 248 sec. sea level isp vs. 285 on the RD-253 and 365 on the RS-68). EA gives the LEO performance for Ariane 5 as 16000 kg, but to a 51.5 degree inclination orbit, which is going to cut into the performance a lot. Arianespace's site gives a payload to LEO of 20 tons, which gives a payload/mass fraction of .0257, which is better but still not great. Payload to GTO is 10000/777000, which gives a mass fraction of.0129. Also, Ariane 5 does a bit of the same thing STS does and uses a hydrolox first stage with solid boosters. All the Ariane variants look like they are optimized for launches to GTO/GEO, so their payload fraction to LEO is going to suffer a bit. This explains why Ariane 4 and 5 have lower payload fractions to LEO (as far as I can tell your Ariane 4 numbers are correct). *** To build on my previous calcs; STS gets hurt a bit in the payload/mass calcs since it reuses so much of what it lifts to orbit. A better comparison would be Shuttle C, which likewises uses hydrolox/solids, and has a payload/mass fraction of 77000/1966675 = .0391, which is comparable to Delta IV Heavy. Atlas V 552 (actually any Atlas variant without "0" in the middle digit) has solids in the first stage, which, if my thesis is correct, will lower the payload fraction. Theoretically the best Atlas V config for payload/mass fraction would be the Atlas V 402. Performance data for it can be found in the archived Atlas V Handbook. Adding components from page 25 of that doc, we get a gross mass of 331702 kg for Atlas V 402. Wiki says that 402 has a payload to LEO of 12500 kg, which gives a payload/mass fraction of .0377, which is better, but not by much compared to 552. Interesting.
  10. Scale Models Megathread

    Picked up a model during my Colorado trip. @EnsignExpendable
  11. By now everyone's probably heard that North Korea's probably got their nuclear weapons small enough to fit on an ICBM; https://www.washingtonpost.com/world/national-security/north-korea-now-making-missile-ready-nuclear-weapons-us-analysts-say/2017/08/08/e14b882a-7b6b-11e7-9d08-b79f191668ed_story.html?utm_term=.9e27bcd93746 That article gives an upper bound of 60 warheads (most other sources I've seen are lower, around 20-25). That's more than one for every state! Is America in existential danger? The answer is no, not exactly. 60 warheads is nothing compared to our own arsenal, or what the Soviets had pointed at us back in the day. Assuming each warhead kills 200,000 people (probably an overestimate, North Korea has not yet developed hydrogen bombs, and they are probably reserving a significant amount of their warhead for use against South Korea / Japan / ground forces on the Korean Peninsula) that's 12 million deaths. That would be by far the worst tragedy in American history, and would have massive effects on society as a whole, but it is only a small percentage of our population (ballpark 4%). France about the suffered the same proportion of casualties in World War 1 and won, while Paraguay lost 70% of its male population in the War of the Triple Alliance and still exists nowadays (albeit with less territory than before). Now that I'm done channeling my inner LeMay, what exactly can we do about North Korean missiles? I'm going to discount a preemptive strike; finding road mobile missiles is hard as shit, and any attempt to do that would almost certainly result in a war that leaves thousands if not millions of Koreans, Japanese, Americans, and others dead (this is bad). Here's a great circle route from Wonsan (city on North Korea's east coast) to Albany, one of the farthest northeast targets likely to be hit. (being an asshole, Kim Jong Un will not use one of his warheads to cure America of Patriots fans once and for all) And here's a route from Wonsan to San Diego, about as far southwest as you can get in CONUS. (interestingly enough, the difference in range is only about 700 miles or so) You'll notice that both trajectories fly pretty near Alaska (most trajectories to the middle of the US will actually overfly the state). Clearly, if we want to intercept North Korean missiles, that's where we should put our defences. Boost phase interception is logistically tricky and relies on parking your weapon system right near a nuclear armed country. Terminal phase interception requires you to put a whole bunch of interceptors near any likely target, which just isn't worth it for 60 (probably more like 10) missiles. The US military, not being entirely run by morons, has put their existing missile defenses in Alaska already; https://en.wikipedia.org/wiki/Ground-Based_Midcourse_Defense However, that system has had a mixed record in tests. However, it is getting better, and it probably our best option in the near term for defense against missiles. You can make the problem easier by not requiring a direct hit on the North Korean missile to kill it. Now, instead of having to hit a target travelling at hypersonic speeds with another chunk of metal at hypersonic speeds, you can just get sort of near it. We had that problem solved back in the 70s (though a modern version would need a bit more range to cover all trajectories at midcourse). Of course, detonating 5 megaton warheads in the upper atmosphere opens up a whole political can of worms and other issues and makes people unhappy and oh god it's such a pain. Good luck dealing with that.
  12. The Meteorology Thread: Irmagerd

    East coast is gonna have a fun day: https://www.washingtonpost.com/news/capital-weather-gang/wp/2018/01/02/monster-storm-to-blast-east-coast-before-polar-vortex-uncorks-tremendous-cold-late-this-week/?utm_term=.0f2fa2b0284c 946 mb, have fun
  13. The Meteorology Thread: Irmagerd

    For discussion of all sorts of weather and weather related phenomena. Post cool shit, or just talk about what it's like outside. First, here's a cool pic of some sprites; Also, we're just now starting to get into hurricane season (although it actually began about 5 months ago with Hurricane Alex)! The US has dodged a lot of bullets recently, there hasn't been a landfalling major hurricane in the US since 2005. The biggest story in the Atlantic for 2015 was Hurricane Joaquin, which reached category 4 intensity over the Bahamas despite its unusual method of formation, and sank the cargo ship El Faro; The East Pacific had Hurricane Patricia, which produced the highest winds ever recorded in a hurricane, and the lowest pressure ever recorded in the western hemisphere (872 mb) Side not, California hasn't been hit by a hurricane since 1898. Maybe this is the year they'll get unlucky!
  14. Documents Repository: Small Arms

    https://www.scribd.com/doc/289060202/The-Meanderings-of-a-Weapon-Oriented-Mind-When-Applied-in-a-Vacuum-Such-as-the-Moon
  15. General AFV Thread

    Isn’t a mortar with more propellant pretty much a howitzer (in terms of operational performance?). In any case, that turret looks pretty small for both a 40mm autocann and a 120mm mortar, and it it doesn’t look unmanned. They have also cleverly avoided saying exactly how much their thing weighs.
  16. The Star Wars General Discussion Thread

    Rogue One is still the best new Star Wars movie. relevant;
  17. Education and throwing away your life.

    For a non-snarky answer, it's not something that can be definitively nailed down to a single number. I'm not familiar with specific IQ tests, but based on other tests I've taken (SAT), they measure a lot of how good you are at taking the test. IIRC they (the people who offered the SAT) used to say you couldn't improve your score by studying to game the test, but it appears they finally realized what a load of crap that is.
  18. I’d assume that the US would support Norway in any dispute, due to the NATO connection and desire to contain Russia. Norway’s economy already has a lot of oil money coming in, how are they doing at preventing Dutch Disease? I’ve heard they’re doing better than the middle eastern petrostates, but that’s not exactly a high bar to clear.
  19. Bash the Pak-Fa thread

    Any actual information about 6th Generation fighter designs is deep in the bowels of Groom Lake or its Russian/Chinese equivalent, so sure, why not say it can?
  20. WoT v WT effort-thread

    In case @T___A still gives a shit about wot (I think 705 variants are going to be the 9 and 10)
  21. Election 2020: The Jeb Strikes Back You should have clapped!
  22. Egregious Aviation Safety Violations

    For discussion stupid shit like Pinnacle 3701 and this: http://www.rapp.org/archives/2015/12/normalization-of-deviance/ For reference, here's what a gust lock looks like on a Cessna 172; As you can see, it's essentially a pin that goes in the control column and keeps it from moving. Even starting the airplane with this installed would be utterly ludicrous to me, as would not doing the checklist. If your car runs out of oil in the middle of a drive you're going to have a bad day and engine repair bill, if your plane runs out of oil muffling there's a good chance you're going to turn yourself into chunky salsa on the side of a mountain.
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