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FleshJeb

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    I'm missing something (Timing SRB burn out with Booster burn out)

    in KSP2 Gameplay Questions and Tutorials

    Posted

    What Street said. ISP is kind of BS number. What we're really interested in is the "effective exhaust velocity", which is Ve = g0 * ISP. We just defined it as ISP = Ve / g0 because it's a useful shortcut for other calculations on Earth. These are not typically used for gameplay.

    From wikipedia:

    "Specific impulse, measured in seconds, effectively means how many seconds this propellant, when paired with this engine, can accelerate its own initial mass at 1 g. The longer it can accelerate its own mass, the more delta-V it delivers to the whole system."

    Going Interplanetary - I've seen two methods. Pros and Cons?

    in KSP2 Gameplay Questions and Tutorials

    Posted · Edited by FleshJeb

    20 hours ago, JoeSchmuckatelli said:

    So there is really one window per year per planet for the most efficient transfers. 

    It's when the two planets arrive at the same phase angle again. This is dependent on the ratio of their orbital periods.

    Let's say you want to go from Planet 1 to Planets 2 or 3. As it happens, the angle between 1 and 2 or 3 is optimal at Year 0, Day 0.

    How long does it take until the transfer to each is optimal again? This is a bit incomplete, but it's when they've returned to the same relative positions, which is going to happen when they're at round integers in the chart below.

    Yj78eEQ.png

    As you can see, the less difference between the orbital periods, the more rarely they both line up. In the real world, Mars has an orbital period of about 1.88, and we can get an optimal transfer about every 25 months. A Neptunian year is 165 of ours, so you can basically go every year and change (without gravity assist shenanigans).

    EDIT: If I'd been smart, I'd have compared this all to the hands of an analog clock. It takes longer than one hour for the minute hand to cross over the hour hand again.

    Going Interplanetary - I've seen two methods. Pros and Cons?

    in KSP2 Gameplay Questions and Tutorials

    Posted · Edited by FleshJeb

    16 minutes ago, JoeSchmuckatelli said:

    So - for a duffer like me; doing method 1 is better because it's more efficient and will let me retain more fuel to do work once I get there...  But 2 is okay if you're overbuilt and just goofing around?

    It's KSP, you can try both and see which one you prefer! EDIT: Entirely-Unsuperfluous-J's answer is the more comprehensive one that my brain would not articulate.

    16 minutes ago, JoeSchmuckatelli said:

    Full disclosure: I just finished a contract job and don't go back to work until after Spring Break, so I've been playing a lot yesterday and today.  I kind of feel like the Forum's ADD kid atm.  Just can't stop posting bugs and asking questions!

    I've been enjoying KSP vicariously through your videos. :D I quit my job of 15 years in January, and I'm HEAVILY caffeinated.

    Going Interplanetary - I've seen two methods. Pros and Cons?

    in KSP2 Gameplay Questions and Tutorials

    Posted

    I swear I'm not picking on you, I just click the most recent post on the side, AND you ask good questions. :D

    Method 2 doesn't benefit as much from the Oberth Effect. https://en.wikipedia.org/wiki/Oberth_effect

    The simplified version is that it's always more efficient to do your burns lower in a gravity well, because your orbit is faster down there, and the faster you're already moving, the more additional kinetic energy you get out of the same amount of delta-v expended. A bigger change in kinetic energy means a bigger change in the resultant orbit (Each orbit represents a constant sum of potential and kinetic energy at any given point.)

    Kinetic energy equation: K = 0.5 * Mass * Velocity^2

    If you're already moving 2.0 km/s you have 2.0*Mass km/s of kinetic energy. Add a 1.0km/s burn to that and you have 4.5*Mass km/s. The difference is 2.5*Mass km/s

    If you start at 3.0 km/s, you have 4.5*Mass km/s. Add 1.0km/s again, and you have 8.0*Mass km/s. Difference of 3.5*Mass km/s for the same amount of delta-V expended.

    There's a longer, more comprehensive explanation, but that's the short version. Also, the mass of the spacecraft is irrelevant here, but I left it in for completeness.

    Spacesuits

    in Science & Spaceflight

    Posted

    @sevenperforceSome further items for consideration:

    • How much heat is the expansion of the breathing air from the tanks absorbing?
    • How much gets dumped by venting the CO2? (I'm assuming this is open-cycle.)
    • How much gets dumped by venting the humidity produced by the body? (Also assuming this is open-cycle.)
      • From professional experience, I would assume 2-3L of water consumption over an 8 hour shift at comfortable temperatures. Push that to 4-6L at higher temperatures (35-40C) and exertions. (I wonder how they deal with salt build-up in the suit? At those volumes, a cotton t-shirt will stand on its own just from salt-encrustation.)

    Sensationalist news on plastiglomerates

    in Science & Spaceflight

    Posted

    1 hour ago, lajoswinkler said:

    It's not a theory, but a hypothesis and it's disproven, nowdays circling pseudoscientific and contrarian areas of Internet obsessed with Russia. Crude oil has molecules that have biochemical origin, such as those from decomposition of chlorophyl, a telltale sign of photosynthetic metabolism.

    When I looked into it a few years ago, my understanding was that it was disinformation proposed by the multinational oil companies to get people to ignore Peak Oil, so that they could take advantage of the inevitable economic crisis that would arise by not preparing to transition to different energy sources.

    Duffer's Question about Efficiency - - (Rocket construction: Launch to Orbit & Stages)

    in KSP2 Gameplay Questions and Tutorials

    Posted · Edited by FleshJeb

    http://www.projectrho.com/public_html/rocket/multistage.php

    OK, it's a good link but a high bar.

    On those rare occasions I used rockets, I usually used full throttle SRBs around an underpowered core stage. Light all on launch. Drop SRBs and use core to get just short of circularization. Finished the circularization with the upper (high vac ISP) stage. Upper stage would do the transfer burn to destination, and maybe the braking around the target.

    Patch One is Go

    in KSP2 Dev Updates

    Posted

    13 minutes ago, MARL_Mk1 said:

    What could be causing this?

    Moving your wings along the longitudinal axis will change how your wings Pitch Up/Down, no matter what you tell the vehicle to do...

    In KSP 1, control surfaces flip direction when the rotation axis of the part changes between ahead of and behind the COM.

    That said, you really don't want those wing surfaces to respond to pitch inputs. Since there's not much lever arm that close to the COM, they're not doing much other than acting as airbrakes. I've done enough fighter competitions to know that it will give you slightly better turn performance at the cost of a lot of speed.

    Pretentious Kerman's Unnecessary Report - on Successful Docking? (Makes me think the ship blew up again)

    in KSP2 Suggestions and Development Discussion

    Posted

    Oh sorry, I thought it was in the name list in the program. I figured it made a good ancillary bug report, because there's no way a corporation would want to let that continue.

    12 minutes ago, JoeSchmuckatelli said:

    Got a better appellation for this guy?

    For a pretentious kerbal, it's hilarious--Space is up after all! :D

    Unfortunately humans play this game, and I've seen Jatwaa have to gracefully handle some extraordinarily nasty comments. (I also had occasion to learn that he's as fantastic a guy off-camera as he is on.)

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