egg changed the topic of #principia to: Logs: https://esper.irclog.whitequark.org/principia | <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/ | <egg> calculating the influence of lamont on Pluto is a bit silly…
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<queqiao->
⟨kingparity⟩ how do you use the flight planner in scenarios where the engine won't activate unless it's at full throttle meaning you can't use the activate engines thing of it
<queqiao->
⟨test_account⟩ ⟪kingparity⟫ how do you use the flight planner in […] ⮪ With difficulty 😬
<queqiao->
Must set it to instant impulse and start the burn earlier than principia cutoff time
<queqiao->
⟨test_account⟩ * maneuver
<queqiao->
⟨test_account⟩ So I guess it's similar to how maneuvers are executed in stock
<queqiao->
⟨kingparity⟩ ah
<queqiao->
⟨kingparity⟩ rip
<queqiao->
⟨Bee Rights Activist⟩ we should make solid motors only ignite when throttled up so we can press activate engine for principia purposes
<queqiao->
⟨test_account⟩ it doesn't help when they are on the next stage, and they usually are
<queqiao->
⟨Gratak-⟩ It would be cool if principia optionally allowed manual thrust settings. initial twp, final twp and burn time would be all that is needed, right?
<queqiao->
⟨Gratak-⟩ * settings per maneuver.
<queqiao->
⟨Gratak-⟩ That would also allow planning a larger maneuver over multiple liquid stages
<queqiao->
⟨test_account⟩ But I don't think this is enough: "initial twp, final twp and burn time ". It needs to know not just TWR but also the mass ("W") and it doesn't because of staging.
<queqiao->
⟨Bee Rights Activist⟩ Or you could enter starting/final mass numbers and select the engine(s) you are using for the burn
<queqiao->
⟨test_account⟩ no, selecting anything from next stages is hopeless
<queqiao->
⟨test_account⟩ it needs to be simple
<queqiao->
⟨Bee Rights Activist⟩ ⟪test_account⟫ no, selecting anything from next stages […] ⮪ is there some weird thing in principle that doesn’t allow that
<queqiao->
⟨test_account⟩ no, it's just a nightmare to implement
<queqiao->
⟨test_account⟩ a lot of UI work that surely won't even be considered
<queqiao->
⟨Gratak-⟩ Why would you need mass? thrust per mass and time is all that is important. The only issue is that TWR is actually thrust per mass per current gravity and the latter changes with time and is also not relevant for the maneuver itself
<queqiao->
⟨Gratak-⟩ Selecting the engines manually would be a nightmare. Ideal would probably if you select the stage and principia somehow automatically gets the numbers that MJ has, but I guess that is hardly possible
<queqiao->
⟨Gratak-⟩ But if you would manually give him those 3 numbers from MJ it should work
<queqiao->
⟨test_account⟩ Both thrust and mass is necessary to calculate the maneuver
<queqiao->
⟨test_account⟩ Just TWR... how does it work if neither thrust nor mass is known?
<queqiao->
⟨Gratak-⟩ thrust per mass, not both separately. A craft with 100kN and 100kg behaves the same as one with 1kN and 1kg
<queqiao->
⟨Bee Rights Activist⟩ * principia
<queqiao->
⟨Gratak-⟩ (assuming the end state is again proportionally the same. As I said, start and end TWR are needed)
<queqiao->
⟨test_account⟩ ah ok, TWR basically the same as acceleration and it's all that is needed, yes
<queqiao->
⟨Gratak-⟩ yeah. acceleration is what is actually needed, but afaik that is shown nowhere in RO?
<queqiao->
⟨test_account⟩ on the navball 😛
<queqiao->
⟨Bee Rights Activist⟩ the TWR can be turned into acceleration simply by multiplying by 9.81
<queqiao->
⟨Gratak-⟩ No. Depends on where you are
<queqiao->
⟨Bee Rights Activist⟩ Well surely principia knows where you are
<queqiao->
⟨Bee Rights Activist⟩ the reference frame should tell it that
<queqiao->
⟨Gratak-⟩ Yes. But if you set up the maneuver while at LEO and execute it while at GEO the numbers have changes
<queqiao->
⟨Gratak-⟩ So Principia would need to auto update them with changing gravity. Which is fine, but confusing
<queqiao->
⟨test_account⟩ so TWR is not really a very good number to base it on
<queqiao->
⟨Bee Rights Activist⟩ No, the TWR is the same at GEO as at LEO right?
<queqiao->
⟨Gratak-⟩ Best would be you enter current TWR numbers and when you press ok principia stores them as acceleration
<queqiao->
⟨Bee Rights Activist⟩ exactly
<queqiao->
⟨Gratak-⟩ And if you later want to change them, it can compute them back to the TWR at that time
<queqiao->
⟨test_account⟩ What are the "current" TWR numbers? MJ shows then after selecting a planet and altitude
<queqiao->
⟨Gratak-⟩ ⟪Bee Rights Activist⟫ No, the TWR is the same at GEO as at […] ⮪ No. It includes the altidue. Gravity is much lower at GEO
<queqiao->
⟨test_account⟩ So they are not calculated for "current" conditions
<queqiao->
⟨Gratak-⟩ The ones in flight are current
<queqiao->
⟨test_account⟩ how do you know TWR in flight, for an engine that is not thrusting?
<queqiao->
⟨Bee Rights Activist⟩ the ones in flight take into account changing gravity due to distance?
<queqiao->
⟨Gratak-⟩ MJ dv window has them in flight. For all stages
<queqiao->
⟨Bee Rights Activist⟩ ⟪test_account⟫ how do you know TWR in flight, for an […] ⮪ copy the numbers from mechjeb, it can read future stages
<queqiao->
⟨Bee Rights Activist⟩ the TWR in flight take into account changing gravity due to distance?
<queqiao->
⟨Bee Rights Activist⟩ the TWR in flight takes into account changing gravity due to distance?
<queqiao->
⟨test_account⟩ yes, and MJ dV window doesn't show current numbers, if you are in LEO and select the moon it will show TWR at the moon? or does it work only in the VAB this way?
<queqiao->
⟨Gratak-⟩ MJ dv inflight doesn't let you select the reference. it's always current IIRC
<queqiao->
⟨Bee Rights Activist⟩ Then go back to the method of thrust/wet mass/dry mass
<queqiao->
⟨Bee Rights Activist⟩ Is there a problem with doing that
<queqiao->
⟨Gratak-⟩ Yeah. maybe. It's two more numbers but might be easier
<queqiao->
⟨test_account⟩ Tbh thrust/wet mass/dry mass is more transparent
<queqiao->
⟨Bee Rights Activist⟩ Getting the two mass values would be a bit of a hassle though
<queqiao->
⟨Gratak-⟩ Though thrust is only shown in the full dv window
<queqiao->
⟨Gratak-⟩ I usually don't have that active as it blocks too much space
<queqiao->
⟨Bee Rights Activist⟩ Wait does MJ show future stage wet/dry masses? It might be in the full delta v window in flight
<queqiao->
⟨Gratak-⟩ yes
<queqiao->
⟨Bee Rights Activist⟩ Good then, MJ shows all those numbers, now the question is "how tedious will it be to implement"
<queqiao->
⟨test_account⟩ one more button that opens one more window to enter these numbers and some changes to actually use these numbers in the calculations...
<queqiao->
⟨Gratak-⟩ I'd assume that the current implementation does just that. Compute those numbers and put them as an input. The one thing that is needed is now an inteface to input those numbers
<queqiao->
⟨Gratak-⟩ +instead
<queqiao->
⟨Gratak-⟩ +manually
<queqiao->
⟨test_account⟩ one more button that opens one more […] ⮪ Also some validation to make sure nothing crashes when the user enter nonsense 😬
<queqiao->
⟨test_account⟩ * enters
<queqiao->
⟨Gratak-⟩ That might already be in the function 😅
<queqiao->
⟨Bee Rights Activist⟩ I mean currently principia just integrates the rocket equation or something like that right, so the math shouldn't be too hard
<queqiao->
⟨Gratak-⟩ The math is easy as long as it assumes constant thrust as that is linear
<queqiao->
⟨test_account⟩ which is what MJ shows for solids, fortunately
<queqiao->
⟨test_account⟩ on the other hand, the result will still be approximate, but there is no way to take into account solids thrust curve...
<queqiao->
⟨Bee Rights Activist⟩ Would it be nightmarish to implement a thrust curve
<queqiao->
⟨test_account⟩ tbh I see now that I will not use this window for unguided moonshots, it will miss because of the thrust curve.
<queqiao->
⟨Bee Rights Activist⟩ baby sergeant thrust is relatively linear right
<queqiao->
⟨test_account⟩ well... i don't know
<queqiao->
⟨test_account⟩ but i have two stages of them so there is a weird "thrust curve"
<queqiao->
⟨Bee Rights Activist⟩ it looks linear to me when I used it, at least compared to something like GCRC
<queqiao->
⟨Gratak-⟩ But two stages would be two maneuvers you could set up ahead
<queqiao->
⟨Gratak-⟩ That should be pretty precise then
<queqiao->
⟨test_account⟩ well yes it's possible
<queqiao->
⟨Gratak-⟩ I've never done (and don't plan to) unguided moon shot so I can't say much there
<queqiao->
⟨test_account⟩ but if you don't precision you can just plan it as instant impulse?
<queqiao->
⟨Bee Rights Activist⟩ is there anywhere in the game files that the thrust curve exists
<queqiao->
⟨test_account⟩ +need
<queqiao->
⟨Gratak-⟩ I'd like the feature for a two stage interplanetary burn
<queqiao->
⟨test_account⟩ ah yes, can't plan the second stage with the current interface
<queqiao->
⟨test_account⟩ but you also have the "thrust curve" issue with that
<queqiao->
⟨Gratak-⟩ Why?
<queqiao->
⟨Gratak-⟩ All liquid engines
<queqiao->
⟨test_account⟩ first engine has TWR 1 --> 5, second has TWR 1.5 --> 7, overall TWR varies in weird ways
<queqiao->
⟨Gratak-⟩ But principia would correctly compute those
<queqiao->
⟨Bee Rights Activist⟩ can you just plot two burns back to back
<queqiao->
⟨Gratak-⟩ ⟪Bee Rights Activist⟫ can you just plot two burns back to back ⮪ Yes. But right now the second would be wrong if it uses a different stage
<queqiao->
⟨test_account⟩ no, you only have three numbers, wet mass at first stage ignition, dry mass at the end and "thrust" (which one)?
<queqiao->
⟨test_account⟩ ah i see, the numbers are for the second stage
<queqiao->
⟨Gratak-⟩ It would be two maneuvers
<queqiao->
⟨Bee Rights Activist⟩ ⟪Gratak-⟫ Yes. But right now the second would be […] ⮪ Then use the thrust wet dry method for the second
<queqiao->
⟨test_account⟩ hmm yes
<queqiao->
⟨test_account⟩ ok yes it can be done
<queqiao->
⟨Bee Rights Activist⟩ to make it easier just add a button to snap the start of the second burn to the end of the first
<queqiao->
⟨test_account⟩ no, you need time between the burns
<queqiao->
⟨Gratak-⟩ And I have had this case so often in my current career. I design a craft for Jupiter Moons. Then realise it will work just as well for Saturn moons and beyond. But then the departure stage is not strong enough and has to lend something from the capture stage
<queqiao->
⟨Gratak-⟩ I'm not designing a new craft in that case
<queqiao->
⟨Bee Rights Activist⟩ I have discovered the thrust curve for the GCRC and confirmed that the baby sergeant has no thrust curve
<queqiao->
⟨Bee Rights Activist⟩ it just does normal variance
<queqiao->
⟨test_account⟩ You can actually use one stage to raise apoapsis a bit, then replan and make a second burn after an orbit
<queqiao->
It's a lot of work and can create EC and boiloff issues though
<queqiao->
⟨Gratak-⟩ In that case I leave orbit with the first stage
<queqiao->
⟨test_account⟩ no, a weak first stage that has 2000dV at most
<queqiao->
⟨Bee Rights Activist⟩ ⟪test_account⟫ You can actually use one stage to raise […] ⮪ Just do the back to back burns and accept the inaccurate result, surely this is more accurate than instant impulse inertial
<queqiao->
⟨Gratak-⟩ And if you have people on bord you don't want to get back through the radiation belts...
<queqiao->
⟨test_account⟩ this is worse (
<queqiao->
⟨Bee Rights Activist⟩ If you have people on board you wouldn't be subjecting them to 11G by strapping solid kick stages to the back
<queqiao->
⟨Gratak-⟩ No solids. Two liquid stages
<queqiao->
⟨Gratak-⟩ Again, just that I can't plan the second
<queqiao->
⟨Bee Rights Activist⟩ variance of liquids is low compared to solids, I think it should still be accurate enough
<queqiao->
⟨Gratak-⟩ No. The wrong TWR makes it go off quite a bit
<queqiao->
⟨Gratak-⟩ It assumes that TWR just goes higher after the first stage runs out
<queqiao->
⟨Gratak-⟩ instead in goes down a lot
<queqiao->
⟨test_account⟩ There is no such thing as "accurate enough" for interplanetary... it's accurate or it's not
<queqiao->
⟨Gratak-⟩ There is. The question is how expensive you have to correct
<queqiao->
⟨test_account⟩ I don't want to correct for more than 100m/s!
<queqiao->
⟨Bee Rights Activist⟩ ⟪Gratak-⟫ instead in goes down a lot ⮪ then do the two burn method and enter thrust wet mass dry mass
<queqiao->
⟨Gratak-⟩ me neither. That's why I hope for this feature
<queqiao->
⟨Gratak-⟩ ⟪Bee Rights Activist⟫ then do the two burn method and enter […] ⮪ that is what I hope for, yes
<queqiao->
⟨test_account⟩ in fact, i often have less than 100m/s for corrections on unmanned probes.
<queqiao->
⟨egg⟩ Looks like the bridge is still up after nearly a week; but the screenshots noticeably eat into the available memory (more so than the cats!)
<queqiao->
⟨siimav⟩ Why does the bridge hold all the cats _hostage_?
<queqiao->
⟨egg⟩ Why does the bridge still call Starmincer Starmincer?
<paculino>
Why does the bridge not allow embeds when my client normally does?
<raptop>
So the bridge is saying that you should post cats instead of purple noodles?
<queqiao->
⟨kingparity⟩ what is the bridge?
<paculino>
The bridge is the magpies with joined wings going to the mockingbird's nest.