JoeSchmuckatelli

So... Yes. And yes! While I haven't played KSP for a while, I've known that it's absolutely possible to keep a space object oriented however we want it. I've also presumed that orbiting objects maintain their inertial attitude. What I'm struggling with is more abstract. I saw the full eclipse this year. It got me to thinking about the Eddington experiment that confirms Einstein - Minkowski space time for most folks. Under this framework gravity isn't a force like magnetism but a curvature of spacetime where objects in space (including light) move along 4 dimensional geodesics. In other words, orbits around massive objects are defined /caused by the the curvature of spacetime. So... Okay. But. If this is truly correct... Why is it that things in orbit maintain the inertial attitude? The earth maintains its internal attitude around the sun (hence the seasons) just as a refrigerator would around the earth. If spacetime is truly curved - how is inertial attitude maintained at all? Why doesn't an orbiting object move more like a car on a track? (or orbital rate attitude?)

Thanks! Getting the terminology correct is always a better way to phrase a question (hell even finding out what the terminology is is crazy hard sometimes!)

Thanks! This part is what I was looking for. It makes sense. ... Although, when I started reading about Minkowski space my head twisted up and I began to wonder whether curved space would make an object in orbit follow the curve... Ah heck I can't describe what I was thinking! Gracias!

Thanks - that answers some of my questions. I guess what I want to know is how an orbiting object behaves differently from a plane. I know that a plane in suborbital flight is kept aloft by lift, and as it travels around the world its bottom will always be pointed 'down' / parallel to the surface (level flight). But a space craft is in a ballistic free fall, going fast enough to keep missing the planet. As such, I'm trying to figure out whether it would circle the earth like a plane (nose forward the whole time) or if it would maintain the orientation it had when it entered orbit - ie if it entered orbit with the belly towards the sun - would it keep that orientation throughout the orbit? Where you write 'depends on the orientation mode chosen' - I can infer that mission control could do whatever they wanted - but what is the 'natural state'? Or what would a defunct satellite or even a refrigerator do once in orbit? Would it be tidally locked or show the same face only when in the same part of the orbit?

I've read that as the shuttle orbited the earth it kept the bay doors toward the surface and the bottom of the shuttle toward the sun. I believe the reason for this was to keep the thicker shielded bottom of the shuttle between the crew and the giant radiation hazard we call the sun. Similarly, I've read that ISS cupola faces the earth to give the crew a view of home, and I've seen night and day pictures of the earth taken by crew of the ISS. The question I'm curious about is this: are the bay doors of the shuttle and the cupola of the ISS oriented on the surface during a full orbit? (i.e. Once in orbit, does the craft maintain its orientation to the surface like a plane in flight, and/or does it require gyros to keep the window /bay facing the surface?) The problem I have is that part about keeping the bottom of the shuttle between the crew and the sun. I'm wondering if the shuttle bay doors were open to the day side during the sunward part of the orbit, but open to the darkness of space while on the night side of the planet. Ultimately, what I would like to know is whether keeping one side of a spacecraft facing the surface requires gyros (or whatever), or whether, once in orbit a craft would 'naturally' fly 1/4 of the orbit backwards, then 1/4 nose to the earth, then 1/4 forward and the final 1/4 with the tail pointed to the earth. Thanks in advance for any info!

This relates to a couple of past threads where I learned about using Tylo or Laythe to get a Joolian orbit without massive expenditure of fuel. The clock has been ticking, and I'm getting ready to do my burn to achieve a Tylo encounter (for the second try). I've placed a maneuver node - and to get the proper encounter I need (using a NERV) a 25 second (73 m/s) burn - and the burn requires mostly Radial Out, a middling amount of Retrograde and a touch of Normal. This places the dark blue maneuver marker about 5 degrees off the Radial Out marker. On my first attempt I lined up on that marker and fired the engine for the required time... and completely lost the encounter. Now - what I did not do was follow the marker when it started to wander - just kept my orientation where it was originally. So - the reason behind the question - I've seen some guys manually 'feather in' their burns - firing aimed at the Radial Out for a while, then rolling to Retro for a squirt or two, then Normal and back to Radial Out to get the alignment they want, all the while zoomed in on the planetary system to see the effects of their burns. Seems fiddly - but it obviously works. The main question is - for a guy with a passing understanding of what is going on - is that a better method than 'aiming at the dark blue maneuver marker and hoping the computer lined me up correctly. And a final question: should I try to follow the blue marker when it wanders?

Grumble grumble grumble... I have a knuckle dragger solution that works. Now you guys are telling me my baby ain't as pretty as I thought she was! (Grin) Okay - back to the drawing board. I guess I'll play with some SRBs at lower stages as well - I've been burning liquid fuel + Ox at the cyclic rate. Thanks for the input folks - every time I post on here... I learn something new.

Well, I found this Thread where Frostiken explained the answer to my dilemma in This Post (above) (I assumed a radial 1.25 would be dramatically more draggy than the Thud - given the visual models): Without doing any math - I've always assumed a single 2.5m tank (which holds as much fuel as the four 1.25s) with two radial engines would be a better solution than cobbling together four tanks and four engines - turns out its not... and I'm going to have to play with a new lander design...

Hmmm. Okay - I can see how a single thruster underneath the fuel tank will have less drag - and I understand (I think) about the efficiency. But that doesn't answer why people use 4 symmetrical fuel tanks with small inline thrusters (which had to have been launched with higher drag than two Thuds...)

Been checking out other people's work, and I'm surprised I don't see my lander engine of choice used more often. In fact, what I usually see is something like 4 "Spark" engines on 4 FL-T800 fuel tanks (given 4-way symmetry). I typically just put two thuds on 2-way symmetry on a single X-200 type fuel tank. Is this a hold-over from the way things were done back in the day - or is there a good reason to not use "Thuds" in the current build? (B/C... you know... they do work after all.) (FWIW - my Thud's are typically used as the final thrust to SOI change, insertion Pe to gain orbit, land, take off and return to orbit then to orbit around Kerbin all in the final stage from Minimus / Mun (haven't gotten further afield yet).)

I've read that they do - but I cannot tell. Going to assume the problem is on my end, so here's where I'm at: I bought a new, base level engineer and flew him in a mining craft to the Mun (yeah I know) - and landed the craft next to another engineer I'd landed there previously. Started up the mining craft with the base level guy and checked the numbers. Then I brought over the other Engineer - thinking two on board would improve things. Didn't happen. The new engineer didn't change the numbers (either on the drill or the convertotron). So - is mining only dependent upon one engineer? Does stacking them do nothing? Both of them are in the ship - do I need them to be out? (And does the fact that I have a probe core controlling the ship affect anything?) The whole reason I took the ship to the Mun in the first place was to pick up the second engineer to make a Minimus mining mission more efficient... but that doesn't seem like a good idea now. What am I missing? Game is mostly vanilla (except for Alarm Clock and Real Burn Time mods) For what it's worth - Thermal efficiency is 100%, Batteries are full, three XL solar collectors active and sun at high noon. There's no problem with the ship - it's merely that I don't see any change from the mining or refining with one Engineer or two.

I have no idea what the right sub-forum would be for this, but thought I'd ask (in case anyone knows): Would it be possible to have an earth-like planet with two moons, where both moons are approximately the same apparent size when viewed from the surface - i.e. where both moons could eclipse the sun - as our moon does? I've figured out that the farther moon must be substantially larger than the near moon - but have no idea whether a system like this could be stable.

That's starting to sound like the way to do it... If I do it. As of right now it just seems easier to launch a fuel tank - then launch my mission package, and refuel from that tank. Thus far I haven't run into prohibitive costs in my Career mode game - but might just do a small mining operation at Minimus just to complete a contract (Initially I was thinking some over engineered huge mining ship). Unless someone can tell me it turns out to be cheaper to refine fuel at Minimus and ship it to Kerbin for example, I'm starting to wonder if there's any reason to do anything other than launch fuel from Kerbin.

I looked at this - but want to be sure I get it. Does this mean that for a Kerbin - Moho run, I should circularize a 700km orbit until the transfer window opens, then decelerate until I get a low Kerbin Pe, and then accelerate at Pe out of the system?

I don't have the maths to figure this out myself - but is there a significant difference in efficiency determined by where you start? Obviously, a LKO burn gives you higher initial speed - but then you're starting out having to fight all of Kerbin's gravity to escape - whereas with a Minimus burn you're starting from a lower gravity body... I presume if you start from Minimus you want to wait until the moon is going retrograde to Kerbin's orbit to go to the inner planets - but prograde to the outer - or does that matter? ... Where I am going with this is - trying to decide whether it's worth my time to set up a mining operation on Minimus to assist in exploring the rest of the system.

After reading this - I decided to go try the TT-38K (the small one) and it worked - catastrophically. The rocket design I am comfortable with (at my level of tech) has two 'Skippers' flanking a 'Mainsail' (the 3 engines are level with one another). The Skippers are supposed to burn approximately 3/4 of the Mainsail burn, then I drop them. I have - till now - used the Hydraulics almost exclusively - because they've never blown up my ship. Trying out the TT-38s resulted in detonation of the lower fuel canister and Mainsail engine upon separation. So I tried out the TT-70 with strut connectors - and that worked fine. Was a bit hairy - but no explosion - which is a good thing. Based on this - I may stick with the TT-70 for future builds. But I will say - there's something majestic and comforting with the way the Hydraulics eject the radial stages.

On a mission to recover a Kerbil and his scrap - got the Kerbil - but the scrap fell through the surface of Minimus (and keeps falling through, no matter whether I reload, shut down and reload, etc...). Now the contract is unable to be completed - can I cancel the contract and still get partial credit - or should I let it fail for the single missed element of the mission (recover the scrap...)? What to do?

So I had an Orange Body tank in LKO that I'd used as a fuel tanker for two other ships. After emptying it I used RCS thrusters to drop the Pe to ensure a reentry destruction of the empty (and now useless vessel) - and out of kicks watched its reentry to see when it would explode. It didn't. The craft was just an orange body, a grabber, two Thuds and an Octo with some RCS thrusters and tanks. NOTHING burned off of it - and I'm convinced that had I had a parachute (or even perhaps some more monopropellant) I could have landed the thing safely. How is it possible for the tank to survive reentry without a heat shield? Am I wasting weight using heatshields?

Learn something new every day. Thanks - that will come in handy!

Does anyone else do this? I just discovered it. I had to do another Minimus run to gain some cash for other missions - and goofed my initial burn. The correction burns I tried - kept over-correcting - either giving me too high a Pe or having me miss the encounter entirely. But rather than reverting to a previous save - just for kicks I thought I'd see what the RCS thrusters would do - and they gave me an almost perfect insertion Pe. I'm certain I'm not the only one who does it - but does anyone do this regularly? It seems to work very well. Especially where you've one ship with a lot of Dv that gives you fits trying to fine-tune an insert.

Delete this post - I was wrong...

I just literally had a moment of stunned realization. An epiphany. And not because I am any good at math - but because I am a carpenter. And I would have never known my love of carpentry would help me understand anything in physics. I had to read your post about 3 times to get it - but, holy frijoles, Batman! It's the Pythagorean theorem in action - and I had only a gist of what you were describing at first read - but now I'm getting it. (Carpenter's use a 'cheat' to know if something is square: we measure 3 feet in one direction from a corner and mark it, four feet in the other direction and mark it - and if the building is square... the space between the two marks should be 5 feet.) To think that my angular momentum after a gravity assist would end up being C2... I am stunned. Thank you!

At this point, assuming anything but that I'm 'certifiably cuckoo' is a questionable assumption at best. - but yes, I'll be orbiting prograde (whew!). Thanks for the answers guys! Hmmm. I 'get' it as far as the game goes - but have to ask; why does the ship's speed not even out? I.e. as the ship enters the moon's SOI, retrograde, shouldn't it be accelerated by the moon's gravity (as it falls toward the moon from the retrograde side) by the same or a similar amount as it reduces the ship's velocity by decelerating it as the ship climbs out of the moon's well on the prograde side? I know you've given me the correct answer - just idly wondering why the net effect isn't zero. I'm guessing that this has to do with the velocity transfer at Pe, but don't quite understand how it works.

I did a fabulous job of not explaining the context when I posted this. Snark subsequently posted the context; which was to create a unique thread (out of a discussion originating elsewhere) - for the benefit of myself and others - on how to use orbital mechanics rather than a ton of fuel to do an elegant insert into Jool. In my defense, it was late and whiskey was involved. (Grin!) Here's the link to that discussion: http://forum.kerbalspaceprogram.com/index.php?/topic/129741-nerv-rocket-use-stupid-from-low-kerbin-orbit-jool/ I found myself with a similar problem when I first started playing with maneuver nodes to attempt what you guys suggested in the other thread - specifically maneuver nodes bouncing from place to place and the entire thing being very jumpy; it was disconcerting to try to figure out the right way to do it with that happening... but I got the gist. What I'm a little unclear on is where I want my line in relation to the moons. @Snark wrote, "One is when you are still "descending" -- that is, you haven't reached Jool periapsis yet, your Jool altitude is still decreasing. In this case, you want your trajectory to cut right in front of Laythe (on its prograde side), so that it will slow you down." (emphasis mine) In one scenario that has popped up as I played with the maneuver nodes - the Laythe encounter had me coming 'inside the circle' of Laythe's orbit during my flyby, but it went past and crossed Laythe's orbital plane on the prograde side - is that 'cutting right in front of Laythe'? Or is 'cutting right in front of Laythe' done as Plusck shows in his first image where the line goes outside the orbital path and cuts back across the orbital path in front of the moon? Does it matter?

Having stumbled and been helped along the way into an upcoming Jool Encounter - I'm looking for tips to 'do it right the next time.' @Snark suggested this thread: Looking to send men and machines back into the fray - but with less risk / frustration. EDIT: This question relates to a discussion found in this thread: http://forum.kerbalspaceprogram.com/index.php?/topic/129741-nerv-rocket-use-stupid-from-low-kerbin-orbit-jool/ . We decided to post this as a unique thread to help me (and others) understand how to use orbital mechanics for an elegant insert that saves fuel - rather than the brute-force 5 minute retrograde burn I had planned.