JoeSchmuckatelli Posted January 31, 2022 Share Posted January 31, 2022 10 hours ago, SOXBLOX said: Nah. The focus of the solar gravitational lens is waaay out there, on the very farthest edge of the solar system. The Wikipedia page says the focal point is at 542 AU, which is 360-something times the orbit of Mars. You still get a gravitational lensing effect at Mars, you just can't really use it for imaging things. It's like looking through a pair of glasses sideways. I'm often amazed at how wiki has answers to questions I think might be unique. Thanks for the info & link! Quote Link to comment Share on other sites More sharing options...
TheSaint Posted January 31, 2022 Share Posted January 31, 2022 3 hours ago, kerbiloid said: 1. The Shuttle was able to lift 29.5 t. 2. The Shuttle was able to return 14.5 t. 3. The Shuttle didn't have any flight abort option but separating and gliding to a runway. How can the Shuttle land with the 29.5 t heavy cargo on flight abort, when it was able to land just 14.5 t? (The abort modes included both atmospheric and suborbital options). I don't have access to any technical insight here, just intuition: Carrying the higher payload weight would produce more heat and/or atmospheric pressure load during reentry and abort sequences. Even though such loading may not produce immediate failure it could produce stress beyond design levels that could potentially weaken the vehicle structure and reduce the overall vehicle life. I wouldn't be at all surprised to learn that a suborbital abort with a max payload may exceed nominal aerodynamic design specs, but you know, they do it anyway, since they don't really have a choice. So, my guess is, the 14.5 t return payload is based on, "Carrying this payload through reentry and landing on every mission will not produce stress that will impact the projected operating lifespan of the vehicle," while the 29.5 t to orbit is based (at least in part) on, "Carrying this payload through any abort mode may exceed nominal design operating specifications, but will not produce stress that will result in a loss of the vehicle." Because planning your payload weights around having an abort sequence on every launch would be, well, kinda pessimistic. I remember, from back in my Canoe Club days, The GreenThing (USS Greenling, SSN614) had a "depth-excursion incident", and went well below her test depth, almost exceeding crush depth. After this was all done, they didn't decommission her or anything like that. They NDTed the hull to figure out exactly what damage had been done, sat down with their slide rules and metallurgy books, and rerated her hull. She had new depth limits and a new operating envelope calculated just for her. (Well aren't you special!) So I suspect that if one of the shuttles had ever had an abort or some other aerodynamic excursion that didn't result in a hull loss, a very similar process would have taken place. They would have NDTed the frame, calculated it all out, and then said, "Okay, this vehicle is now rated for X more flights, with these new payload restrictions." Quote Link to comment Share on other sites More sharing options...
tomf Posted January 31, 2022 Share Posted January 31, 2022 How would gravitational lensing be useful for a telescope? The Wikipedia page starts by saying that it doesn't act as a focusing lens at all and light from a point is smeared to a line but then talks about the solar gravitational lensing. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted January 31, 2022 Share Posted January 31, 2022 3 minutes ago, tomf said: How would gravitational lensing be useful for a telescope? https://www.universetoday.com/149214/if-we-used-the-sun-as-a-gravitational-lens-telescope-this-is-what-a-planet-at-proxima-centauri-would-look-like/ 6 minutes ago, TheSaint said: So, my guess is, the 14.5 t return payload is based on, "Carrying this payload through reentry and landing on every mission will not produce stress that will impact the projected operating lifespan of the vehicle," while the 29.5 t to orbit is based (at least in part) on, "Carrying this payload through any abort mode may exceed nominal design operating specifications, but will not produce stress that will result in a loss of the vehicle." I had same guessing, that 29.5 would be an "extreme overload causing the vehicle decommission". (But physically possible,) Quote Link to comment Share on other sites More sharing options...
Shpaget Posted January 31, 2022 Share Posted January 31, 2022 (edited) 1 hour ago, Hyperspace Industries said: Since water rockets lose pressure (and therefore thrust) as water (and therefore mass) is shot out the back, could you be able to tune a water rocket to have a constant thrust to weight ratio? What would you need to tune? The volume of pressurized air bubble. Edited January 31, 2022 by Shpaget Quote Link to comment Share on other sites More sharing options...
lrd.Helmet Posted January 31, 2022 Share Posted January 31, 2022 4 hours ago, kerbiloid said: It was built by 1985, long before the ISS, and even before the idea that Mir-2 and Freedom projects can be united. And it was developed as a replacement for all existing launch vehicles, to fly every two weeks. So, 29.5 t were for reasons. Yeah, but If you build something with enough dV to get 15t to a 400km orbit, because for whatever reason that's what you need it for. Then you get 30t to 200km. For example, falcon 9 was designed to bring x amount of cargo to LEO, thanks to the design of the rocket the first stage has enough dV to be an SSTO (a useless one, but still). It wasn't designed to be one and it wasn't a design requirement, but it was a consequence of other design decisions. It would be interesting to know what the original performance specification was for the shuttle. Quote Link to comment Share on other sites More sharing options...
RKunze Posted January 31, 2022 Share Posted January 31, 2022 (edited) 5 hours ago, Hyperspace Industries said: Since water rockets lose pressure (and therefore thrust) as water (and therefore mass) is shot out the back, could you be able to tune a water rocket to have a constant thrust to weight ratio? Maybe, but I doubt it (See below). 5 hours ago, Hyperspace Industries said: What would you need to tune? Assuming you don't actually fit a controllable throttle on the thing, the only parameters you can tune at all are the initial volume ratio of air to water (i.e. the volume of the air bubble), and the initial pressure. I'm not sure you can actually get it to be constant though. Haven't really calculated it, but basically to get a constant TWR you need to have T(t)/m(t) = const (with T(t) the thrust over time, m(t) mass over time), both are directly dependent on the mass flow m'(t), you don't have any control over the shape of m'(t) because mass flow is determined by the air pressure over time, and the formula for that (adiabatic expansion, for some reasonable assumptions in the water rocket case) does not look like it would balance out in the thrust to mass quotient simply by fiddling with the initial volume and pressure. Anyway, the question is kind of pointless, since a real water rocket (at the least the small single stage variants you can build out of plastic bottles) basically "burns out" (if that is the right expression here...) directly off the pad¹. If you want to calculate it, just model it as an instant impulse. ¹ real world experimental data my kids and I did with a simple water rocket built out of a 1 litre PET bottle: "Main engine cutoff" occurs at a height of about 1.5m above the launch pad after a "burn time" of less than 0.1 seconds, apoapsis is at roundabout 30m (a bit difficult to measure exactly), total flight time is around 10-15 seconds. Edited January 31, 2022 by RKunze Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 1, 2022 Share Posted February 1, 2022 (edited) 8 hours ago, lrd.Helmet said: If you build something with enough dV to get 15t to a 400km orbit, The delta-V is provided by the integrated launch vehicle, not by the spaceplane itself. (It just carries the core stage engines). The cargo is limited by the structural strength of the spaceplane cargo bay on overloads, of the wings on aerobraking, of the gear on landing. That's what I mean. Edited February 1, 2022 by kerbiloid Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted February 1, 2022 Share Posted February 1, 2022 16 hours ago, kerbiloid said: 1. The Shuttle was able to lift 29.5 t. 2. The Shuttle was able to return 14.5 t. 3. The Shuttle didn't have any flight abort option but separating and gliding to a runway. How can the Shuttle land with the 29.5 t heavy cargo on flight abort, when it was able to land just 14.5 t? (The abort modes included both atmospheric and suborbital options). Operational limits. An abort is a contingency scenario, where LoV is acceptable if it can save the crew. Who cares how hard it lands as long as it’s not smeared. Any landing you can crawl away from…. Quote Link to comment Share on other sites More sharing options...
lrd.Helmet Posted February 1, 2022 Share Posted February 1, 2022 (edited) 4 hours ago, kerbiloid said: The delta-V is provided by the integrated launch vehicle, not by the spaceplane itself. (It just carries the core stage engines). The cargo is limited by the structural strength of the spaceplane cargo bay on overloads, of the wings on aerobraking, of the gear on landing. That's what I mean. I might just be stupid, but if you never intend to go to low LEO and thus never exceed the 14t limit then the 30t capability doesn't matter. Apparently the heaviest payload was the Chandra x-ray observatory, at around 22,7t. During STS-93. So I stand corrected. Edited February 1, 2022 by lrd.Helmet I thought I knew things. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 2, 2022 Share Posted February 2, 2022 https://www.sarao.ac.za/media-releases/new-meerkat-radio-image-reveals-complex-heart-of-the-milky-way/ This thing in the middle is what we are revolving around. Isn't this frustrating? Quote Link to comment Share on other sites More sharing options...
Gargamel Posted February 2, 2022 Share Posted February 2, 2022 3 hours ago, kerbiloid said: https://www.sarao.ac.za/media-releases/new-meerkat-radio-image-reveals-complex-heart-of-the-milky-way/ This thing in the middle is what we are revolving around. Isn't this frustrating? Looks like a Rorschach test. Quote Link to comment Share on other sites More sharing options...
lrd.Helmet Posted February 2, 2022 Share Posted February 2, 2022 3 hours ago, kerbiloid said: https://www.sarao.ac.za/media-releases/new-meerkat-radio-image-reveals-complex-heart-of-the-milky-way/ This thing in the middle is what we are revolving around. Isn't this frustrating? these pictures made me wonder. You can see all those filaments and "clouds" and stuff, but that's just because it's so far away. If you were to be in one you couldn't actually see it right? Is it possible that we ourselves are in something that looks amazing from a distance or are we in just a very ordinary arm of the milky way where nothing really happens? Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 2, 2022 Share Posted February 2, 2022 (edited) Moon 1958+ and the real nature of the First Lunar Race. https://warspot-ru.translate.goog/15171-zavoevanie-luny?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru And the thing which probably devalued and cancelled the First Lunar Race, making any lunar outpost vulnerable for ridiculous price.(Actually from which I got the impression that it was not a stupid expensive flagplanting, and started seeking,) Spoiler Because Spoiler And then Spoiler Apollo-20 was cancelled before it, but -18 and -19 several months later. Several years later both parties have scrapped their lunar programs. Edited February 2, 2022 by kerbiloid Quote Link to comment Share on other sites More sharing options...
SunlitZelkova Posted February 2, 2022 Share Posted February 2, 2022 2 hours ago, kerbiloid said: Moon 1958+ and the real nature of the First Lunar Race. https://warspot-ru.translate.goog/15171-zavoevanie-luny?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru And the thing which probably devalued and cancelled the First Lunar Race, making any lunar outpost vulnerable for ridiculous price.(Actually from which I got the impression that it was not a stupid expensive flagplanting, and started seeking,) Reveal hidden contents Because Reveal hidden contents And then Reveal hidden contents Apollo-20 was cancelled before it, but -18 and -19 several months later. Several years later both parties have scrapped their lunar programs. As I have mentioned my previous posts, there are mountains of evidence against this. That said though, the stuff about the military Saturn Vs and ASAT Lunar Module derivative were interesting. Quote Link to comment Share on other sites More sharing options...
caecilliusinhorto Posted February 2, 2022 Share Posted February 2, 2022 Would it be possible to make a simplified fuel injector which mixed the two propellant with two pipes converging into one, sort of like a mixer tap, which then is injected into the chamber? This probably has lots of issues but would it actually work? Quote Link to comment Share on other sites More sharing options...
DDE Posted February 2, 2022 Share Posted February 2, 2022 4 minutes ago, caecilliusinhorto said: Would it be possible to make a simplified fuel injector which mixed the two propellant with two pipes converging into one, sort of like a mixer tap, which then is injected into the chamber? This probably has lots of issues but would it actually work? It wouldn't result in decent mixing, and would invite flame up into your injector. Some of the injector designs do feature something remotely what you're suggesting, but you're still looking at dozens of separate mixers. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 3, 2022 Share Posted February 3, 2022 Running into a mental block. Appreciate some maths help (re: spreadsheet) Just for fun, I'm trying to write a formula or rather create a spreadsheet that will tell me how long I've spent staring at the count-down timer for a certain game. The timer is always 30 seconds. I also have the total number of battles I've played - but I want to make it 'general' so that I can run how much time has been spent staring at that timer for a player who's played 10,000 battles, 15,000 battles and so on. I want the output to be in Weeks, Days, Hours and Seconds. Problem is, I can work out each of those separately - i.e. know that a player who's logged 20,000 battles has spent 6.94 days or 0.99 weeks of their life staring at that countdown timer; but that's not the output I hope to achieve. What I'd rather output is something that shows a player with 25,000 battles has spent 1 week, 1 day and 12 hours, 47 minutes and 30 seconds* of their life staring at the timer. So how do I set up the spreadsheet to run the numbers, round to the nearest whole 'week' or 'day' and then send the remainder to the next column? Bonus, if there is no 'whole' (i.e. week), I'd like it to be zero; just showing 6 days, 17 hours, etc.? Thanks in advance for anyone willing to help me out! *(not the actual numbers, shown for example purposes) Quote Link to comment Share on other sites More sharing options...
K^2 Posted February 3, 2022 Share Posted February 3, 2022 19 minutes ago, JoeSchmuckatelli said: Problem is, I can work out each of those separately - i.e. know that a player who's logged 20,000 battles has spent 6.94 days or 0.99 weeks of their life staring at that countdown timer; but that's not the output I hope to achieve. What I'd rather output is something that shows a player with 25,000 battles has spent 1 week, 1 day and 12 hours, 47 minutes and 30 seconds* of their life staring at the timer. The two functions you want are MOD and FLOOR. So if you want number of minutes that didn't make it into whole hours, that's MOD(FLOOR(seconds / 60, 1), 60) Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 3, 2022 Share Posted February 3, 2022 1 hour ago, K^2 said: The two functions you want are MOD and FLOOR. So if you want number of minutes that didn't make it into whole hours, that's MOD(FLOOR(seconds / 60, 1), 60) That worked perfectly - thanks! Quote Link to comment Share on other sites More sharing options...
magnemoe Posted February 3, 2022 Share Posted February 3, 2022 2 hours ago, JoeSchmuckatelli said: Running into a mental block. Appreciate some maths help (re: spreadsheet) Just for fun, I'm trying to write a formula or rather create a spreadsheet that will tell me how long I've spent staring at the count-down timer for a certain game. The timer is always 30 seconds. I also have the total number of battles I've played - but I want to make it 'general' so that I can run how much time has been spent staring at that timer for a player who's played 10,000 battles, 15,000 battles and so on. I want the output to be in Weeks, Days, Hours and Seconds. Problem is, I can work out each of those separately - i.e. know that a player who's logged 20,000 battles has spent 6.94 days or 0.99 weeks of their life staring at that countdown timer; but that's not the output I hope to achieve. What I'd rather output is something that shows a player with 25,000 battles has spent 1 week, 1 day and 12 hours, 47 minutes and 30 seconds* of their life staring at the timer. So how do I set up the spreadsheet to run the numbers, round to the nearest whole 'week' or 'day' and then send the remainder to the next column? Bonus, if there is no 'whole' (i.e. week), I'd like it to be zero; just showing 6 days, 17 hours, etc.? Thanks in advance for anyone willing to help me out! *(not the actual numbers, shown for example purposes) Is the countdown timer always 30 seconds? Now it could be for matchmaking reasons you want players at around the same level in an match but does not want to wait to long to find an perfect match and the scoring system is inaccurate anyway but for some matches you will be the last filling the group and you go at once as in you are an tank in an MMO But It could simply be the loading screen and the matchmaking is done on server while clients loads and its 30 seconds to get potatoes with slow drives loading the level so they don't start 20 second after the guys with fast SSD. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 3, 2022 Share Posted February 3, 2022 Just now, magnemoe said: Is the countdown timer always 30 seconds? Now it could be for matchmaking reasons you want players at around the same level in an match but does not want to wait to long to find an perfect match and the scoring system is inaccurate anyway but for some matches you will be the last filling the group and you go at once as in you are an tank in an MMO But It could simply be the loading screen and the matchmaking is done on server while clients loads and its 30 seconds to get potatoes with slow drives loading the level so they don't start 20 second after the guys with fast SSD. The countdown timer starts after the match is seeded. I think it's there so that potato-clock computer users have a chance vs the SSD crowd. Russian game: I'll give you one guess as to which one! Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 4, 2022 Share Posted February 4, 2022 This is possibly one of the coolest False Color images out there: The Milky Way’s center looks like contemporary art in this image | Science News Also: Earth has a second known ‘Trojan asteroid’ that shares its orbit | Science News Quote Link to comment Share on other sites More sharing options...
Shpaget Posted February 4, 2022 Share Posted February 4, 2022 9 hours ago, JoeSchmuckatelli said: Russian game: I'll give you one guess as to which one! Is it the one with all the lemming trains? Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 4, 2022 Share Posted February 4, 2022 (edited) 6 hours ago, Shpaget said: Is it the one with all the lemming trains? Oh yes... O very much so! SMH Edited February 4, 2022 by JoeSchmuckatelli Quote Link to comment Share on other sites More sharing options...
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