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…
<queqiao->
⟨butcher6994⟩ I just let my geo sats drift, they don't tend to get that far out before becoming obsolete anyway
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⟨kuzinat0r⟩ Not if your surface are coverage margins are thin. Australia-UK connection is quite sensitive
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⟨kuzinat0r⟩ * area
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⟨.popvapor⟩ Someone told me mechjeb would execute my manuevers, but it's blowing past them
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⟨.popvapor⟩ * flight plan manuevers, but it's blowing past them. What gives?
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⟨.popvapor⟩ For some reason the little bar to the right of the navbar that shows how far through your burn you are isn't depleting, even though I blew past the deltav of the burn while mechjeb had me pointed at the manuever node...
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⟨.popvapor⟩ * mechjeb blew past the deltav of the burn while it
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⟨.popvapor⟩ * the ship
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⟨kuzinat0r⟩ It just can't execute it perfectly. But you'll end up overshooting much more)
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⟨kuzinat0r⟩ Just accept the fact you're gonna need to correct your trajectory
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⟨.popvapor⟩ It's not that it's overshooting it a little, it's just not stopping
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⟨kuzinat0r⟩ That one is quite easy. It can't take staging into account. It only calculates the burn for a currently active engine
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⟨.popvapor⟩ The currently activated engine is the one it's using
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⟨.popvapor⟩ I manually staged ~15s beforehand to allow mechjeb to restart the engine
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⟨kuzinat0r⟩ You're firing 2 sets of solids...
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⟨kuzinat0r⟩ And why do you need to spin yourself with a guided stage?
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⟨kuzinat0r⟩ Also, even if I don't see this on video, but you should do all your staging before even planning the maneuver
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⟨.popvapor⟩ Yeah but those solids are staged after the engine that mechjeb is firing
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⟨.popvapor⟩ I literally can't
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⟨.popvapor⟩ I have to fire the red solids 10s before the main engine or the main engine won't start
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⟨ezsnack⟩ or you just ullage with rcs that you already have?
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⟨ezsnack⟩ this will never work if you dont understand why you need to read the wiki on how active engine works
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⟨ezsnack⟩ * engines
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⟨.popvapor⟩ How? forward RCS isn't working on the agena
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⟨kuzinat0r⟩ Ok, if you insist on this approach, then you should check "inertially fixed" and press "instant impulse". It wouldn't be very accurate, but still better
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⟨ezsnack⟩ ok so add 2 rcs only for forward control?
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⟨.popvapor⟩ Yeah because this is the cannonical build for the agena
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⟨.popvapor⟩ I don't understand what is meant by "tweaking the manuever" -- I didn't touch the manuever after creating it
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⟨ezsnack⟩ in that case mj wouldnt throttle up until ignition in principia flight plan goes to 0s
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⟨.popvapor⟩ Yes, that is what's happening
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⟨.popvapor⟩ Mechjeb is throttling up just fine, issue is that the deltav meter for the node isn't changing
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⟨.popvapor⟩ That's what i don't understand
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⟨kuzinat0r⟩ That's not the issue. That's an expected behavior
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⟨ezsnack⟩ i typed the opposite tho, mj should NOT throttle up before ignition = 0s
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⟨ezsnack⟩ +and you should be locked out from throttling up yourself too
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⟨.popvapor⟩ I was
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⟨.popvapor⟩ I did not throttle up myself...
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⟨.popvapor⟩ Mechjeb locked the throttle to 100 and blew past the manuever
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⟨ezsnack⟩ which means that you moved the manouver after clicking execute, which we cant tell for sure as the video starts with execute pressed already
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⟨kuzinat0r⟩ With this approach your best bet is an instant impulse maneuver
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⟨.popvapor⟩ Yeah but I want to understand why mechjeb is blowing past these manuevers
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⟨kuzinat0r⟩ That's why
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⟨.popvapor⟩ But again, the active engine when I created the manuever is the active engine when manuever executes
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⟨ezsnack⟩ _read the wiki_ you dont understand how it works
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⟨kuzinat0r⟩ Man, these solids increase your speed, and decrease your mass, so the main engine accelerates you even more
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⟨ezsnack⟩ you are both changing trajectory and weight, the prediction is meaningless at that point
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⟨ezsnack⟩ a rcs can ullage you for 300grams and keep the prediction relevant
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⟨ezsnack⟩ +.3dv
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⟨kuzinat0r⟩ You literally can't do maneuvers like that. It voids your warranty
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⟨.popvapor⟩ I literally can't do manuevers in the way this rocket was designed to in real life? That seems kind of asinine
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⟨kuzinat0r⟩ I didn't say it's impossible. Nut you're gonna need to calculate everything by yourself
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⟨kuzinat0r⟩ * But
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⟨.popvapor⟩ Calculate what though, that's what I'm not understanding...
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⟨.popvapor⟩ I can't find anything on the wiki that explains why mechjeb wouldn't cut the engines after reaching the parameters given by the node. I've checked:
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⟨vlood⟩ I have to ask why you're not just using fore rcs thrusters for ullage
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⟨kuzinat0r⟩ Because I doubt mechjeb knows anything about principia trajectories. I think all it knows is where to aim, when to throttle up, and when to throttle down
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⟨.popvapor⟩ It doesn't know when to throttle down, thats the issue!
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⟨.popvapor⟩ And i can't figure out why
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⟨egg⟩ Because it knows where to throttle down if it throttled up as planned.
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⟨egg⟩ Which is not what happened, because you did something unplanned.
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⟨kuzinat0r⟩ You won't be able to. Just don't do that
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⟨.popvapor⟩ So it's able to throttle up by magic, but can't throttle down?
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⟨.popvapor⟩ Principia has to be feeding it some information, because it's throttling up on it's own
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⟨egg⟩ You planned a manegg.robin.lro@gmail.comxuFJ7ne6eqei1hoDE3X1
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⟨.popvapor⟩ Why is principia telling mechjeb to throttle up but not to throttle down?
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⟨nazfib⟩ How MJ executes Principia nodes is this:
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- At T-{lead time}, it starts measuring dV expended
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⟨.popvapor⟩ Did you watch the video I posted?
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⟨.popvapor⟩ Mechjeb overshoots my node by all my remaining DV
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⟨.popvapor⟩ It activates the engine and just keeps burning until it's depleted
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⟨.popvapor⟩ 22m/s I can deal with no problem, 2400m/s is an issue
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⟨egg⟩ Principia is not telling MechJeb anything. You planned a manœuvre. It starts at a certain time, it ends at a certain time. MechJeb replicates that. If you do not start in the same conditions as the plan (which does not have the preceding solid burn), you are not executing the plan, and MechJeb does not know what you actually meant, only what you planned.
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⟨egg⟩ Wait, that is strange.
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⟨.popvapor⟩ Evidently it's not that simple -- because if it was the DV bar would deplete
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⟨kuzinat0r⟩ I also noticed it activated the engine well before the countdown reached zero. Probably, you've edited the maneuver after pressing "execute", or staged, or did something else.
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⟨egg⟩ No, that it will never do with Principia.
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⟨egg⟩ But MechJeb should know that it is executing a Principia manœuvre, cut off.
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⟨vlood⟩ Fairly sure that no longer works ever since vanilla dv readouts have been disabled
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⟨vlood⟩ * stock
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⟨clayel⟩ > our RCS is perfectly reliable, and we have perfect ullage informationin before the next testflight update adds rcs
<raptop>
Imagine doing the du thing for RCS
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⟨ezsnack⟩ seemingly stupid question but whats the recommended way to update principia? lol