Jool System Orbital Error

[GarrisonChisholm]

Good afternoon all.  The heading of this question was almost going to be "What did I do wrong", however that could hardly be descriptive of anything as it would start with what shoes I put on today.

I had read that approaching a planet in Front (by orbital rotation) of its orbit would subtract speed from your velocity and there-fore aid in your orbital capture.  I was sending a probe ship to Laythe, and so entered orbit on Jool's prograde side so it would help slow me down.  I managed to maneuver an encounter with Laythe without much difficulty, but when I entered its SOI i found my velocity was ~7500 m/sec.  I had no HOPE of arresting this with my puny ion engine.

It seems that logically, to subtract Laythe's speed I must approach from its Retrograde, yet will not Laythe act then to accelerate me?  It suddenly seems like I will need a very large breaking engine on my final stage, making for a very heavy rocket.  I am ruling out an aero-braking attempt as I have read too much about how dangerous and tricky they are.

So; 'what did I do wrong?'   :?

Edited January 4, 2016 by GarrisonChisholm

[Snark]

Screenshot of your trajectory in map view would be nice. 

So here's your problem:  You can't use a gravity assist from a body to help with your orbital velocity for other things in that body's SoI.  For example:  You can use a Jool reverse gravity assist if you're going to some other planet beyond Jool (none in stock, but hey, maybe you're running OPM), but not to go to a moon of Jool.  Once you're inside Jool's SoI, whether you're on Jool's prograde or retrograde side only matters to things outside of Jool's SoI.

If you want to get a gravity assist in the Jool system to capture to the Jool system, you need your gravity assist from one of the moons (generally Laythe or Tylo, because of their size)-- not from Jool itself.

The way this would work is that you do a flyby of Laythe or Tylo, which doesn't capture you to the moon but does slow your Jool-relative velocity down to the point where you're captured to Jool.  Then you can loop around and do more gravitational billiards on a subsequent pass, if needed.

For example, if you want to use a gravity assist from Laythe to slow down, there are two types of path that will work.

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.

The other is when you're ascending-- that is, you enter the Jool system, go to some Jool periapsis that's lower than Laythe's orbit, pass periapsis, then you encounter Laythe when you're on your way back "up" again.  Here, again, you want to cut in front of Laythe (on its prograde side), again so it will slow you down.

Edited January 4, 2016 by Snark

[GarrisonChisholm]

Ohhh!   ...Well, ...crap. LOL ...my mission is shot then.  I'm literally in a retrograde orbit  of Jool with my PE at Laythe's altitude above Jool and my AP 10 days out, I imagine beyond even Bop (though I am not home to confirm this).  My only plus side is my 3.1 ton probe (chance remembrance from before shut-down this morning) has over 2000 units of Xeon for its ion engine.

 

Thank you for such a swift reply, but I don't see how I can save this one.  It was supposed to orbit Laythe and dip in to sample its atmosphere.  I have a highspeed pass coming up tonight to attempt the sampling anyway.  I will try to grab some screen shots, though I still would need an IMGUR account.

[Snark]

1 hour ago, GarrisonChisholm said:

Ohhh!   ...Well, ...crap. LOL ...my mission is shot then.  I'm literally in a retrograde orbit  of Jool with my PE at Laythe's altitude above Jool and my AP 10 days out, I imagine beyond even Bop (though I am not home to confirm this).  My only plus side is my 3.1 ton probe (chance remembrance from before shut-down this morning) has over 2000 units of Xeon for its ion engine.

Thank you for such a swift reply, but I don't see how I can save this one.

So, you can still salvage this, I think.

First, you need to correct your retrograde orbit of Jool.  To do this, wait until you're out at your 10-day apoapsis, then thrust until you've reversed your orbital direction.  This shouldn't take a super lot of dV; when you're out that far, your orbital velocity is low.  So now you're in a Big Inconvenient Elliptical Orbit, instead of a Big Inconvenient Elliptical Orbit in the wrong direction. 

The next step is to lower your approach speed to Laythe.  To do this, you need to bring your Ap down to something approximating Laythe's.  What's your dV budget like?  Do you still have lots, or are you heavily constrained?

If you still have lots of dV, then just do a retrograde burn when you're at Jool periapsis to lower your Ap down to the height of Laythe's orbit, then when you get an encounter you match velocity with Laythe.

If you're heavily constrained on dV, you could use a reverse gravitational assist from Tylo or Laythe to lower your periapsis and save some dV.

 

1 hour ago, GarrisonChisholm said:

It was supposed to orbit Laythe and dip in to sample its atmosphere.  I have a highspeed pass coming up tonight to attempt the sampling anyway.

Be aware that this won't work.  You can't dip into the atmosphere during a high-speed flyby to sample it.  KSP was deliberately designed to prevent this:  if you're traveling faster than escape velocity, then all your science results will count as "in space near Laythe" rather than "in Laythe's upper atmosphere," even if you're actually physically in the atmosphere.  You'll get all the physical effects of heating, drag, etc. but no contract completion and no science.  The only way to get atmospheric science is if you're either on an orbital or suborbital trajectory, not on escape.

So you have to capture to Laythe to make this work.

 

1 hour ago, GarrisonChisholm said:

I will try to grab some screen shots, though I still would need an IMGUR account.

Note, you don't need any account to use imgur.com.  Just go to the site, choose "Upload Pictures," and drag 'em there.  Works just fine.  Quick and easy, no account required.

Edited January 5, 2016 by Snark

[FancyMouse]

5 hours ago, GarrisonChisholm said:

I managed to maneuver an encounter with Laythe without much difficulty, but when I entered its SOI i found my velocity was ~7500 m/sec.

It sounds like you entered at the exact opposite direction where Laythe orbital velocity adds to your velocity.

[GarrisonChisholm]

Just a follow-up, and thanks to Snark for his immediate and expert aid!

The orbit was reversed successfully, but the cost of lowering the Ap to Laythe was scary ( >2000 dV) so I did an aerobreaking pass through Laythe, and following my plane change (the aerobreaking made my eccentricity worse) I will see if I have the budget to lower Ap or if I need to design a Jool aerobreaking pass.

Thank goodness this probe was so over-supplied with Xenon, the dV of all my mistakes is enormous.  Down to 1500 units though for my 3 ton probe (not sure what that translates to- I think its at least double, but I don't want to find out the hard way).

[Snark]

29 minutes ago, GarrisonChisholm said:

Just a follow-up, and thanks to Snark for his immediate and expert aid!

The orbit was reversed successfully, but the cost of lowering the Ap to Laythe was scary ( >2000 dV) so I did an aerobreaking pass through Laythe, and following my plane change (the aerobreaking made my eccentricity worse) I will see if I have the budget to lower Ap or if I need to design a Jool aerobreaking pass.

Thank goodness this probe was so over-supplied with Xenon, the dV of all my mistakes is enormous.  Down to 1500 units though for my 3 ton probe (not sure what that translates to- I think its at least double, but I don't want to find out the hard way).

To calculate your remaining dV:

• Take the total mass of your ship, including fuel.
• Then take the "dry" mass (i.e. without fuel).
• Divide the total mass by the dry mass.  This is your mass ratio.
• Take the natural log ("ln" on your calculator) of the mass ratio.
• Now multiply by the Isp of your engine, and by Kerbin gravity (9.8 m/s²).
• This is your remaining dV in m/s.

So in your case,

• Total mass is 3 tons.
• Xenon mass is 1500 units times 0.0001 per unit Xe, or 0.15 tons.  So dry mass is 3 - 0.15 = 2.85 tons.
• Mass ratio is 3 / 2.85 = 1.052.
• ln(1.052) = 0.0513
• 0.0513 * 4200 sec (Isp for ion engine) * 9.8 m/s² = 2111 m/s.

So yes, you have enough, but not double enough-- conserve fuel.    But it looks like you can still do this.

In retrospect, given how much of your dV budget it cost to lower your Ap, it probably would have been a good idea to pick up a reverse gravity assist from Tylo or Laythe to shave a bunch off of that.  But oh well, what's done is done, and you can still do a lot with 2100 m/s.

This is the first time you've mentioned a plane change-- are you not in an equatorial orbit?  Plane changes can be pricey, especially at Jool.  It's best to avoid them if at all possible.  Sorry, I was assuming you were equatorial all the way, here-- if you have any plane changes to make, it would have been better to make them when you were way out at your 10-day Jool apoapsis, when it would have been cheap.  Plane changes are best made when your velocity is as low as possible, i.e. way out at high apoapsis.  Again, what's done is done, but if you have any remaining plane changes to make, it's best to do them at the slowest speed possible.  (Or, if you can manage another Laythe encounter, use Laythe's gravity to do the work for you.  Does your AN/DN around Jool lie on (or close to) Laythe's orbit?  If so, you can get Laythe encounters without needing a plane change.

 

[GarrisonChisholm]

No, its not your fault.  My original inclination was not significant enough to warrant bothering with, ( ~5*), but the aerobraking pass I made at Laythe (which took 6 days off my 10 day PE) was a last minute plan change (I had originally planned to dump the Ion to use the final stage Ant to capture, but managed enough guesstimation math to realize it wasn't going to work) and so a shoddy trajectory-  it increased my inclination to roughly 30*.

This is my first attempt in the playground/minefield of Jool, so I will congratulate myself on the foresight to send so much Xenon and just take everything else as a learning experience. 

I am getting sick of 20 minute "burns though", which because of low power I do at 1/3 thrust and then endure a 3-1 time delay due to my PC; 1 second of Game time takes about 2-3 seconds of clock.  It's a small part number on the probe, it's just an awful laptop for gaming.  One makes due though.

Tonight will be the plane change, then evaluation of what kind of aerobreaking I can get away with to try to match my AP to Laythe's 21m km (currently it is roughly 36m).

- I will check my AN, I seem to recall it *is* near Laythe...

Edited January 5, 2016 by GarrisonChisholm

[Snark]

1 hour ago, GarrisonChisholm said:

This is my first attempt in the playground/minefield of Jool, so I will congratulate myself on the foresight to send so much Xenon and just take everything else as a learning experience. 

Absolutely!  MOAR BOOSTERS XENON!  (At least with xenon, it's not so heavy to pack along some extra.)  By the way, don't know if you've noticed, but xenon fuel tanks have a hideously crappy mass ratio, i.e. the empty tanks are heavy relative to the xenon fuel.  So if you ever find yourself designing an ion ship with multiple xenon tanks in it, it's seriously worth considering adding decouplers so you can drop tanks as soon as they're empty, so you're not lugging around the dead weight.

In any case, "better bring extra fuel" is an excellent strategy when you're dipping your toe in the Jool pool.  Good job.

1 hour ago, GarrisonChisholm said:

I am getting sick of 20 minute "burns though", which because of low power I do at 1/3 thrust and then endure a 3-1 time delay due to my PC; 1 second of Game time takes about 2-3 seconds of clock.

Yeah, ion burns are dull.  At least they've added some pretty exhaust to look at!  Used to be they just glowed.

I've noticed that on computers that have trouble keeping up, sometimes things go faster if you switch to map view-- it appears to put a lower load on the graphics card, or something.  Might be worth a try.

By the way-- you do know that you can engage physics warp while ion-thrusting, yes?  That is, hold down the ALT key, then the "." to increase physics warp.  You can do that up to 4x, and get your ion burn done in 1/4 the wall-clock time.  I'm guessing you're already doing this, just want to make sure you're aware in case you're not.

1 hour ago, GarrisonChisholm said:

Tonight will be the plane change, then evaluation of what kind of aerobreaking I can get away with to try to match my AP to Laythe's 21m km (currently it is roughly 36m).

Well, good luck!  Just make sure to do your plane change before you drop your Ap, you'll save dV that way.  And if you can possibly manage it, try to get Laythe to do your plane change for you.  Those plane changes really eat up the dV.  And again, if you can make your AN/DN be right at the spot where your Pe crosses Laythe's orbit, then it may be best to just not bother with a plane change at all and plan your Laythe encounters so that they happen right at the node. Adjusting the position of AN/DN by a bit is a lot cheaper than trying to totally change your inclination.

(The above advice assumes that you don't care about what your orbit inclination is when you're finally captured at Laythe, i.e. any old orbit will do.)

Speaking of planning encounters-- do you know the maneuver-node trick so you can plan encounters multiple orbits in the future?

Edited January 5, 2016 by Snark

[GarrisonChisholm]

15 minutes ago, Snark said:

A) By the way, don't know if you've noticed, but xenon fuel tanks have a hideously crappy mass ratio, i.e. the empty tanks are heavy relative to the xenon fuel.  So if you ever find yourself designing an ion ship with multiple xenon tanks in it, it's seriously worth considering adding decouplers so you can drop tanks as soon as they're empty, so you're not lugging around the dead weight.

B.) Yeah, ion burns are dull.  At least they've added some pretty exhaust to look at!  Used to be they just glowed.

C) I've noticed that on computers that have trouble keeping up, sometimes things go faster if you switch to map view-- it appears to put a lower load on the graphics card, or something.  Might be worth a try.

D) By the way-- you do know that you can engage physics warp while ion-thrusting, yes?  That is, hold down the ALT key, then the "." to increase physics warp.  You can do that up to 4x, and get your ion burn done in 1/4 the wall-clock time.  I'm guessing you're already doing this, just want to make sure you're aware in case you're not.

E) Speaking of planning encounters-- do you know the maneuver-node trick so you can plan encounters multiple orbits in the future?

A) Thank you, that is good advice for the future!

B.) Mine still just glow (1.02 until 1.1!).

C) That's good to know, I'll give that a whirl!

D) ...

*bangs head repeatedly on desk to befuddlement & annoyance of co-workers*

E) Mm, no, but let me deal with this headache...

 

...there Really needs to be a "Quick Reference Card" for this game, or a keyboard short-cuts cut-out to layer over the keyboard.

[Snark]

23 minutes ago, GarrisonChisholm said:

B.) Mine still just glow (1.02 until 1.1!).

Seriously?  Should really upgrade to 1.0.5, it's fixed lots of stuff and added others.  But whatever works for you. 

In 1.0.5, the ion drive has a pretty glowing-blue flickering exhaust.  Makes the engine feel a lot more "real", even though real ion drives don't look like that.

25 minutes ago, GarrisonChisholm said:

*bangs head repeatedly on desk to befuddlement & annoyance of co-workers* ...there Really needs to be a "Quick Reference Card" for this game, or a keyboard short-cuts cut-out to layer over the keyboard.

yeah, the game is full of little non-discoverable nuggest like that.  I was playing for months before I discovered that you can turn on physics warp even when you're not in atmosphere by holding down the "alt" key.  All the while grumbling about it, "why the gosh-dang rattin-frattin heck don't they allow physics warp in vacuum, they should allow some way to turn it on..."

Ditto the fact that you can drag maneuver nodes back and forth along a trajectory by grabbing the white circle in the middle.  Ditto the automagical CoM compensation for RCS that happens when turning on fine control mode.  Ditto "absolute snap" mode in the vehicle editor.  Ditto lots of other things I can't recall at the moment.  KSP is a great game, but it has some serious issues with feature discoverability.
 

29 minutes ago, GarrisonChisholm said:

E) Mm, no, but let me deal with this headache...

Fair 'nuff.

The maneuver-node trick I mention is basically a handy planning and dV-saving technique, so that you can do things like "I'll make this tiny burn now so that the target and I will have a rendezvous half a dozen orbits from now" (or whenever).  It's useful in cases like yours, where you have an elliptical orbit that touches Laythe's in just one spot and you need to plan ahead for how to set up an encounter and it may not be practical to do so on the very next orbit.  Lemme know if your headache clears up and you're interested. 

 

[GarrisonChisholm]

11 minutes ago, Snark said:

 

Fair 'nuff.

The maneuver-node trick I mention is basically a handy planning and dV-saving technique, so that you can do things like "I'll make this tiny burn now so that the target and I will have a rendezvous half a dozen orbits from now" (or whenever).  It's useful in cases like yours, where you have an elliptical orbit that touches Laythe's in just one spot and you need to plan ahead for how to set up an encounter and it may not be practical to do so on the very next orbit.  Lemme know if your headache clears up and you're interested. 

 

*humor fail*

I was just trying to launch a witty rejoinder hearkening back to my *bangs head on desk* moment.     I am all ears Sensei, teach on! 

 

[Snark]

So here's the maneuver-node trick for multiple-orbit advance planning:

It relies on the fact that the little icons that get drawn on orbits in map view (e.g. the light-blue "closest approach" markers when your target is a planet) are always for the closest encounter after the last maneuver node.

For example, let's consider the common one-orbit-ahead planning that you're probably used to.  Let's say you're targeting Laythe, and you're in an elliptical orbit whose Pe is right at Laythe's orbit, but the Ap is way out somewhere.  You have no maneuver node set yet. You see a marker somewhere that shows the location of closest approach.  But then consider what happens when you drop a maneuver node at Pe:  if that happens to be after closest approach, then adding the node causes the closest-approach marker to jump to the projected post-maneuver orbit, showing the closest approach after the node.  And when you drag the prograde/retrograde markers on the maneuver node, you can watch how the closest-approach position slides around.  If you want an encounter, you can keep dragging the maneuver node until you get the closest-approach markers to line up.

But what if you can't?  What if Laythe is simply nowhere near where it needs to be, so that in order to get an encounter within one orbit of the maneuver, the maneuver would have to be too big and expensive?  Well, that's what this little trick is for.

Here's what you do to set up your Laythe encounter:

1. Drop a maneuver node right at Pe (or whever is the place you'd ordinarily want to do the burn), the same way you normally would.
2. Look at the projected orbit.  Is the closest approach with Laythe very close?  If so, you can just do a minor prograde/retrograde adjustment to the maneuver node to get them to match up, and then you're done. 
3. But suppose they're nowhere near each other.  So what you do is this:  Go somewhere further along your projected post-maneuver orbit (doesn't matter where, just pick somewhere that's out of your way, like out at Ap or something) and drop a second maneuver node.  This one is just a dummy placeholder; you're not going to give it any dV at all.  Its only purpose is to stake out a time.
4. Now click the "one-orbit-later" button on the dummy maneuver node that you just dropped.  (You know the one I mean, yes?)  Note that when you do this, the closest-approach marker jumps around.  This is now showing you what your closest approach will be one orbit in the future.
5. So... is it reasonably close now?  If so, go back to your real maneuver node (the first one you dropped), and drag its prograde/retrograde handles to adjust the orbit.  Look!  When you do this, the closest-approach marker moves twice as fast as it did before!  That's because you're now making an upcoming maneuver to get an encounter an extra orbit into the future, so that any changes you make to your orbital period will have twice as long to catch up to your target planet.  So what this means is that if you can get an encounter now, you can do so with only half the dV.
6. But let's say that it's still not very close.  Well, you can keep going!  Click the dummy node's "one-orbit-later" button again.  Now you're looking three orbits ahead, and dragging the primary node's prograde/retrograde handles will give you triple-speed adjustment.
7. ...And you can keep doing this, moving one orbit into the future, again, and again, until you get an encounter that you like.  The farther in the future you go, the more sensitive the position of the closest-encounter markers will become to any adjustment you make to the "real" maneuver node.  In theory you can go an unlimited distance into the future; in practice, there's a practical limit at which the maneuver node gets so sensitive that tiny errors in dV make huge differences in encounter locations, and it becomes impractical to control.  But going up to half-a-dozen or so orbits into the future is no problem, and in practice, that's generally always enough.

The nice thing about this approach is that not only does it let you reliably get your Laythe encounter for a very cheap expenditure of dV (no matter how unlucky the current moon alignment is), but it also lets you see any upcoming problems, i.e. you're stepping forward one orbit at a time as described above, and you see "oh crap, on orbit 3 I'm going to encounter Tylo!"  And then you can either turn that to your advantage, or tweak your orbit so that you miss Tylo.

 

[GarrisonChisholm]

45 minutes ago, Snark said:

So here's the maneuver-node trick for multiple-orbit advance planning:

It relies on the fact that the little icons that get drawn on orbits in map view (e.g. the light-blue "closest approach" markers when your target is a planet) are always for the closest encounter after the last maneuver node.

For example, let's consider the common one-orbit-ahead planning that you're probably used to.  Let's say you're targeting Laythe, and you're in an elliptical orbit whose Pe is right at Laythe's orbit, but the Ap is way out somewhere.  You have no maneuver node set yet. You see a marker somewhere that shows the location of closest approach.  But then consider what happens when you drop a maneuver node at Pe:  if that happens to be after closest approach, then adding the node causes the closest-approach marker to jump to the projected post-maneuver orbit, showing the closest approach after the node.  And when you drag the prograde/retrograde markers on the maneuver node, you can watch how the closest-approach position slides around.  If you want an encounter, you can keep dragging the maneuver node until you get the closest-approach markers to line up.

But what if you can't?  What if Laythe is simply nowhere near where it needs to be, so that in order to get an encounter within one orbit of the maneuver, the maneuver would have to be too big and expensive?  Well, that's what this little trick is for.

Here's what you do to set up your Laythe encounter:

1. Drop a maneuver node right at Pe (or whever is the place you'd ordinarily want to do the burn), the same way you normally would.
2. Look at the projected orbit.  Is the closest approach with Laythe very close?  If so, you can just do a minor prograde/retrograde adjustment to the maneuver node to get them to match up, and then you're done. 
3. But suppose they're nowhere near each other.  So what you do is this:  Go somewhere further along your projected post-maneuver orbit (doesn't matter where, just pick somewhere that's out of your way, like out at Ap or something) and drop a second maneuver node.  This one is just a dummy placeholder; you're not going to give it any dV at all.  Its only purpose is to stake out a time.
4. Now click the "one-orbit-later" button on the dummy maneuver node that you just dropped.  (You know the one I mean, yes?)  Note that when you do this, the closest-approach marker jumps around.  This is now showing you what your closest approach will be one orbit in the future.
5. So... is it reasonably close now?  If so, go back to your real maneuver node (the first one you dropped), and drag its prograde/retrograde handles to adjust the orbit.  Look!  When you do this, the closest-approach marker moves twice as fast as it did before!  That's because you're now making an upcoming maneuver to get an encounter an extra orbit into the future, so that any changes you make to your orbital period will have twice as long to catch up to your target planet.  So what this means is that if you can get an encounter now, you can do so with only half the dV.
6. But let's say that it's still not very close.  Well, you can keep going!  Click the dummy node's "one-orbit-later" button again.  Now you're looking three orbits ahead, and dragging the primary node's prograde/retrograde handles will give you triple-speed adjustment.
7. ...And you can keep doing this, moving one orbit into the future, again, and again, until you get an encounter that you like.  The farther in the future you go, the more sensitive the position of the closest-encounter markers will become to any adjustment you make to the "real" maneuver node.  In theory you can go an unlimited distance into the future; in practice, there's a practical limit at which the maneuver node gets so sensitive that tiny errors in dV make huge differences in encounter locations, and it becomes impractical to control.  But going up to half-a-dozen or so orbits into the future is no problem, and in practice, that's generally always enough.

The nice thing about this approach is that not only does it let you reliably get your Laythe encounter for a very cheap expenditure of dV (no matter how unlucky the current moon alignment is), but it also lets you see any upcoming problems, i.e. you're stepping forward one orbit at a time as described above, and you see "oh crap, on orbit 3 I'm going to encounter Tylo!"  And then you can either turn that to your advantage, or tweak your orbit so that you miss Tylo.

 

I am amazed.  O.O  - I've been playing for 7 months, and feel like such a noob!

I am grateful for these tips, and the time you spent sharing them (which was not insignificant).  I now feel Laythe will not only be orbited, but orbited tonight.

[FullMetalMachinist]

Sorry to butt in, but I had some input on this comment:

6 hours ago, GarrisonChisholm said:

...there Really needs to be a "Quick Reference Card" for this game, or a keyboard short-cuts cut-out to layer over the keyboard.

I believe that this thread is what you were hoping for. As I'm just a newbie, I don't presume to know anything that Snark doesn't, so I'll just assume that he missed that small aside. But several of the 'hidden' features of KSP that were mentioned are visible on that map. Hope this helps!

[GarrisonChisholm]

Wow! Thanks for the tip!  I've wanted something like that.

 

Very kind of you! 

[Snark]

2 hours ago, FullMetalMachinist said:

Sorry to butt in, but I had some input on this comment:

I believe that this thread is what you were hoping for. As I'm just a newbie, I don't presume to know anything that Snark doesn't, so I'll just assume that he missed that small aside. But several of the 'hidden' features of KSP that were mentioned are visible on that map. Hope this helps!

lol, nobody knows everything in this game.  I sure don't.  Thanks for pointing out that thread!

(and welcome to the forums!)

[GarrisonChisholm]

Garbage- and can't delete it.

 

Ok, well, I had pictures but I can't take the time at work to figure out what-the-heck I need to do to post them.  However! The upshot is the attempt failed.  I will try to learn from this, and ensure that all of my Jool-system capture attempts occur at Hohman points.

Edited January 7, 2016 by GarrisonChisholm
Sanity via LaytheDragon

[Plusck]

On 4/1/2016 at 11:54 PM, GarrisonChisholm said:

...

I had read that approaching a planet in Front (by orbital rotation) of its orbit would subtract speed from your velocity and there-fore aid in your orbital capture.  ...

 

The way it is supposed to work is that if the heavy orbiting body catches up with you, you get dragged around it and then thrown out forwards along its orbital path - thus theoretically adding the body's original orbital speed to your own. If you catch up with it, you get pulled around and thrown backwards - thus subtracting its orbital speed from your own.

However, in KSP it hardly ever works exactly like that because with few exceptions (Eve, Jool), moons and planets are not massive enough to make such a huge change in your trajectory if you are travelling at interplanetary speeds.

So what you want to do is benefit from the most useful part of that phenomenon to help you out. No moon is heavy enough to spin you right round, but many of them are heavy enough to give you a quarter turn or so. So you cut in front of the moon at an angle so that it accelerates you backwards, or you cut behind it so that it accelerates you forwards.

And because of the way they form, solar systems are naturally set up to help you out. When you transfer up from Kerbin to Duna, and assuming that you have made the absolute minimum transfer to get an intercept, Duna will be going faster than you and will therefore catch you and throw you forwards after you pass behind it. The opposite should happen for Eve : you catch up with Eve just at the edge of its SOI, so you pass in front of the planet and are thrown back at a slower speed along its orbital path when you return to Kerbol SOI. And the same is true of the moons - when Jool is catching up with you at your Ap from a Kerbin-to-Jool transfer, the closest moons to you should be the ones on the inner edge of the Jool system, and their speed relative to you should therefore be slower than the Jool system as a whole.

[LaytheDragon]

5 hours ago, GarrisonChisholm said:

Garbage- and can't delete it.

 

Ok, well, I had pictures but I can't take the time at work to figure out what-the-heck I need to do to post them.  However! The upshot is the attempt failed.  I will try to learn from this, and ensure that all of my Jool-system capture attempts occur at Hohman points.

Look in the URL bar while the album is opened on Imgur. At the end of the URL, there should be a random assortment of letters and numbers. This is the album's "ID". Copy the album's ID. Then, click the edit button at the bottom of your post, and delete the broken album within your post. To delete it, try clicking right behind (to the left) of the first word after the album in the post. Click backspace until it deletes (should be once or twice). Then, click the Imgur Album button, and paste the album ID that is the random assortment of numbers and letters from the URL bar on the album's page. The album should embed properly now.

Alternatively, you can just put a link to the album in your post, by pasting the full URL (which you probably accidentally put into the embed Imgur Album prompt instead of the album ID) into your post. This won't embed it within your post, though.

Once your album is displaying properly, more advice/help can be given. If your difficulty settings allow it, you could have made frequent separate quicksaves that you could revert to if something were to go wrong (I usually use the regular F5 quicksaves, in addition to quicksaves -9 through 9, and also a few named quicksaves, using alt+F5). If you did make quicksaves recently, you do not have to give up unless you are satisfied with the results.

[GarrisonChisholm]

1 hour ago, LaytheDragon said:

Look in the URL bar while the album is opened on Imgur. At the end of the URL, there should be a random assortment of letters and numbers. This is the album's "ID". Copy the album's ID. Then, click the edit button at the bottom of your post, and delete the broken album within your post. To delete it, try clicking right behind (to the left) of the first word after the album in the post. Click backspace until it deletes (should be once or twice). Then, click the Imgur Album button, and paste the album ID that is the random assortment of numbers and letters from the URL bar on the album's page. The album should embed properly now.

Alternatively, you can just put a link to the album in your post, by pasting the full URL (which you probably accidentally put into the embed Imgur Album prompt instead of the album ID) into your post. This won't embed it within your post, though.

Once your album is displaying properly, more advice/help can be given. If your difficulty settings allow it, you could have made frequent separate quicksaves that you could revert to if something were to go wrong (I usually use the regular F5 quicksaves, in addition to quicksaves -9 through 9, and also a few named quicksaves, using alt+F5). If you did make quicksaves recently, you do not have to give up unless you are satisfied with the results.

Thank you for so patiently helping a frustrated stranger.  I thought I was fed-up with it.

My orbits should be visible, but most people will just find it amazing that I failed to achieve orbit with so much dV on-hand.  I don't think I will re-load, I prefer to let "life happen", and just learn from failure. I *am* however interested in learning from this failure.

I think my next attempt will not rely on such tiny engines for one thing, just for my sanity's sake...