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DDE

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Posts posted by DDE

    For Questions That Don't Merit Their Own Thread

    in Science & Spaceflight

    Posted

    Are torn wires a problem for ground-to-ground wire-guided missiles? I'm wondering because in the late 1980s the Soviets began to switch over to laser or radio-command guidance (sometimes both) but nobody else seems to have followed suit, either staying with TOWs/MILANs, or going fire-and-forget (which primarily addresses a different problem).

    Spoiler

    The reason for the question is the Bulat, a new complimentary mini-missile for the Kornet ATGM, which seems to inherit the big brother's datalink system. The Soviets previously built the Metis as the smallest of a trio of infantry ATGMs, and they made the missile extra-cheap by stripping it of any electronics - the wires control the fin motors directly. Since the Bulat appears to be there to address the problem of "I've seen ATGMs get fired against everything except actual tanks", I'm beginning to doubt its economics.

     

    For Questions That Don't Merit Their Own Thread

    in Science & Spaceflight

    Posted

    5 hours ago, ARS said:

    Question: Is it possible for a submarine to do standoff active sonar search by using separate sonar emitters outside of the ship (as in, in the form of buoys, underwater emitters, etc.). Let's say for example submarine A is defending an area, and it already pre-place these emitters around. Then, enemy submarine B is entering A's patrol area. If A knows that B is entering the area, could A detect B simply by staying on passive sonar while periodically pinging the active sonars from the buoys and listening to the echoes to locate B? (could either do sonar pings from the buoys one-by-one or several of them at once)

    Some air-dropped sonobuoy variants are combined with "emitters" that are literal explosive charges, so, yes.

    Russian Launch and Mission Thread

    in Science & Spaceflight

    Posted

    2 hours ago, SunlitZelkova said:

    820th Main Center for Missile Attack Warning just got the false contact of their lives.

    I think Soviet "plasma curtain" tests with train-based emitters have produced more impressive results - the same signature as an entire Chinese MRBM regiment launch.

    This one is a point signature. Also, you're assuming half the center wasn't busy watching it on YouTube.

    The Finances of Space

    in Science & Spaceflight

    Posted

    @JoeSchmuckatelli The guy behind Spydell_Finance on TG just posted an interesting thread in Russian. TL;DR deppsits on US banks exceed lending by 6 trillion (7.3 trillion as of December 2021), which is why deposit rates are in the gutter. The money market and the credit rates are non-responsive to FRS rate hikes because the banks are swimming in virtually free cash... and plus, the disappointed lenders taking the money out of the banks may then spend it and drive inflation up.

    Fun Fact Thread! (previously fun fact for the day, not limited to 1 per day anymore.)

    in Science & Spaceflight

    Posted

    The Objective Individual Combat Weapon was a semi-auto grenade launcher with a regular rifle bolted to it; when the launchers proved troublesome, H&K offered the rifle as a separate system that would become the XM-8.

    According to Ian McCollum, the official feedback for the first iteration was, I kid you not, "Can you make it more Starship Troopers?"

    Spoiler

    This lead to this iteration:

    Screen-Shot-2018-12-05-at-10.42.12-AM.pn

    By the way, the Starship Troopers movie is 25 today.

    Real Life "Kerbalisms"

    in The Lounge

    Posted · Edited by DDE

    TIL that beryllium hydride is a solid. That makes Glishko's RD-550 and RD-560 rocket motors even crazier - they were hybrids.

    And they somehow pumped the damn thing anyway.

    Upd.: apparently they used a screw pump under 100 atm, and then added hot hydrogen gas to produce a "pseudoliquid".

    Fortunately, sufficient amounts of beryllium hydride were not made available for the program to progress significantly, and so Glushko's storeable "improvement in ISP over hydrogen-fluorine" was never fully tested.

    [New] Space Launch System / Orion Discussion Thread

    in Science & Spaceflight

    Posted

    On 10/18/2022 at 11:05 AM, RCgothic said:

    This is a joke. Of course no one else can make SLS rockets. What they should be asking for is vehicles that can perform the mission.

     

     

    Unfortunately, you have to go through such a procedure in procurement every single time. And if it wasn't NASA, they'd probably have GAO breathing down their necks precisely for the reason you enumerated... and so you'd be treated to an amusingly long-winded description of the SLS worded so that SpaceX couldn't troll them by applying.

    First confirmed interstellar meteor!

    in Science & Spaceflight

    Posted

    50 minutes ago, SunlitZelkova said:

    Also I didn't realize until now that "The Galileo Project" is intended to find evidence of alien life in direct connection with UFOs/UAPs. That makes me a little uneasy.

    Damn. Arvi Loeb again. Well, if what he does results in a net good for humanity, let him puff his sizeable ego.

    The Analysis of Sea Levels.

    in Science & Spaceflight

    Posted

    On 11/3/2022 at 3:05 AM, SunlitZelkova said:

    It's a thin line between either or though, of course.

    I think we can should focus on the fact that Greta, She of the Bygone Era Before Coal Resurgence, is not a climate scientist. Therefore, anything she says is based on the works and statements of someone else, and likely suffers from signal loss ('broken telephone'). Instead of arguing whether her statements are political, we can simply and resolutely discount her as a suitable source for the discussion of science :P

    Is a full-flow staged Hydrolox engine possible?

    in Science & Spaceflight

    Posted

    17 hours ago, wumpus said:

    What is missing from the Shuttle engines from that description?  I was pretty sure the were.  Something about it being relatively easier than kerolox.

     

    16 hours ago, sevenperforce said:

    The only difference is that both preburners are fuel-rich, because hydrogen's heat capacity and specific energy are both just so much greater than oxygen that running both preburners fuel-rich makes more sense.

    That, and the US at the time didn't have much experience with oxidizer-rich cycles - Soviet achievements in that department were a bit shocking to them in the 1990s, and SSME had to be built with what was available to the US in the 1970s.

    The bigger question is whether the increase in performance is worth a separate second GG/PB. RD-0120 shows that you don't need such a set-up for SSME-like performance - although it had its own surprises in the form of a concentric dual pump shaft.

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