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StrandedonEarth

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Posts posted by StrandedonEarth

  1. 2 hours ago, farmerben said:

    If you're running a combined cycle power plant into a mostly thermal engine, the inefficiency doesn't mean much.   The key is whether a pure tungsten nozzle can operate at higher temperatures.  Or if you can get some ion thrust by running cathode ray tubes out parrallel to your plasma nozzle.

    Yeah, I was thining it would make more sense as combined cycle, since spacecraft need power. But would it not be more efficient to just keep heating the plasma with microwaves, like VASIMR?

  2. Methagox RCS makes the most sense, if reliable ignition isn’t an issue. The last thing they want is more complexity, especially hazardous chemicals like hypergolics. Although if that’s what they need for HLS, all bets are off…

  3. 4 hours ago, cubinator said:

    It also spent a lot of time with the heat shield only halfway in the plasma at the start there.

    I had to watch the flight while also trying to work, and doing neither particularly well. Now I can catch up on the thread and post…

    What I did notice doing during reentry, after plasma started up, was “wait, now it’s moving sideways?   …. Now it’s upside down?” 

    Whoops, back to work, break was longer than it should have been…

  4. 1 hour ago, darthgently said:

    I'm reminded of what happens when poorly poured solid fuel has big hidden voids, or develops long vertical cracks as it cures, causing the burn rate to go up dramatically, explosively even, with suddenly increased exposed surface area as those voids are opened during burn.  Not saying this happened, just reminds me of that.

    I’m pretty sure those types of defects are found with xray or ultrasound testing 

  5. @Kerwood Floyd They also lost the first three Falcon 1 rockets (but they didn’t “blow up” unless you count the first one crashing) before succeeding on the fourth and final attempt. That story is detailed in the book “Liftoff!” by Eric Berger, which is worth the read IMO

  6. 2 hours ago, TwoCalories said:

    One of my favorites is the F-15N Sea Eagle. This fighter jet could've taken the Tomcat's job, but the Navy turned McDonnell Douglas down due to many factors, including that A) the F-15 was a CTOL craft from the start, and navalizing it would present a lot of issues, but also mainly that B) it couldn't carry AIM-54 Phoenix missiles (or at least not as many) as the F-14.

    I could barely find any good pictures of it, but here is what I could find:

    Putting Eagles Out to Sea – The Tactical Air Network

    Sea Eagle: America's plan to put the F-15 on aircraft carriers

    Were F-15 eagles made from the same frame of an F-14? - Quora

    Does the F-15 even have any decent attachment point for the arresting hook. How much re-design would that have taken?

  7. 3 hours ago, farmerben said:

    Question:  What are the oldest functioning batteries?  

    Batteries have been a commercial product for close to 150 years now and all sorts of chemistries work, some very heavy by today's standards.  I wonder which ones are the longest lasting with functionality, this is an important question for spaceflight too.  Could you make batteries that last a century?  Is there a tradeoff between longevity and weight?

    Google is your friend...

    Oxford Electric Bell - Wikipedia

  8. 2 hours ago, farmerben said:

    Possibly a large moon and tidal oceans are critical for the development of early life on Earth.  Assuming the aquatic origins of life, the exact gravity and atmospheric pressure could probably vary.

    Early theories also postulated that the large moon was necessary to strip away excess atmosphere, preventing a Venus-style runaway greenhouse effect. But I think that theory was disproven, or at least has not gained much traction. 

  9. 19 minutes ago, PakledHostage said:

    Yes. They agree with what I said. I wouldn't post BS. 

     

    18 minutes ago, cubinator said:

    Yep, those few minutes when the Sun's surface is completely covered up are the only time you can look right at it without protection. Its atmosphere is an object you'll only ever see in that moment unless you go to space.

    It's no brighter than the usual daytime sky, which means the light from the corona can't possibly penetrate the filters that makes the rest of the sun safe to look at.

    I was under the impression that the corona still emitted UV, and under the darker skies of totality the eye's pupils open wider, letting in even more. But apparently I was mistaken or misinformed. At least it spurred me to do a little research on that. I edited that post for clarity.

  10. 53 minutes ago, PakledHostage said:

    You can look at totality without eye protection.  In fact, you want to remove your eye protection or you'll miss it. In the moments before totality,  look at the horizon.  If there are clouds around,  you'll see the moon's shadow sweeping in over them from afar at 3000 kph or so. Then once totality starts, it'll be one of the most profound experiences you'll ever have. It gets cold and quiet. All the creatures stop doing their creature things. The sky is dark but there's twilight all around the edge. But don't look at the eclipse before/after totality without eye protection.  Even looking at it with the naked eye a couple of seconds before/after can damage your eyes.

    I was going to call bullcrap, but decided to research first, and got an answer straight from one of the biggest solar experts: Safety (nasa.gov), so I would have been wrong.

    Quote

    Eye Safety for Total Solar Eclipses

    Here are some important safety guidelines to follow during a total solar eclipse.

    • View the Sun through eclipse glasses or a handheld solar viewer during the partial eclipse phases before and after totality.
    • You can view the eclipse directly without proper eye protection only when the Moon completely obscures the Sun’s bright face – during the brief and spectacular period known as totality. (You’ll know it’s safe when you can no longer see any part of the Sun through eclipse glasses or a solar viewer.)
    • As soon as you see even a little bit of the bright Sun reappear after totality, immediately put your eclipse glasses back on or use a handheld solar viewer to look at the Sun.

     

  11. 2 hours ago, sevenperforce said:

    Presumably they didn't want to dump the LOX after reaching orbital velocity because they didn't want to risk the dump causing a propulsive effect

    I’m guessing they need thrust for ullage to dump the LOX, especially at any reasonable flow rate. 

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