Jump to content

How can I achieve sepratron symmetry with asparagus staging?


Recommended Posts

For a long, long time now, I've really wanted to see vertical snap integrated, so that achieving symmetry would generally be easier. Alas, I've never found anything close to that, neither in mods nor settings. A lot of people recommend Editor Extensions Redux, but that doesn't actually provide for vertical snap, but rather allows you to align things on the vertical axis, but only to the center of the parent module. This is often not what I want, and is in fact rather useless when I need a lot of the same part on two sides of a rocket... for example when designing a rocket with asparagus staging.

So, of course I need a bunch of sepratrons on my 6 outer rockets in my asparagus staging. I have however found it impossible to make them actually symmetric on the vertical axis.

How do you do it?

Link to comment
Share on other sites

Having a hard time visualizing what you are saying, a picture may help?

Also, not judging your build or anything but asparagus isn't as important as it used to be back in the old atmosphere, don't feel forced into using it, most don't anymore.

Also, also, let me know if you have questions about getting a pic up here.

Edited by Rocket In My Pocket
Link to comment
Share on other sites

Teekin,

 I align my stuff visually, using a line on the parent's texture as a guide. Not really any other way to do it that I know of.

If you attach the decoupler high and secure the bottom with a couple struts, you won't need to use sepratrons.

Best,
-Slashy

Link to comment
Share on other sites

Objects snap to grid on all three axes if you try to offset them with snap on.

Unfortunately, that will often cause a surface-mounted item to sink into the surface. Some items (the narrow-band scanner, the Gigantor solar array) are extremely annoying since they cannot be offset at all (they sink irrecuperably into the part, and refuse to be offset back to the surface), but most things can then be brought back to the right place with snap off in a consistent manner just by eyeballing it.

If I need to use a Separatron, I usually just use one on top of the nosecone of the booster or tank in question, pointing slightly up and towards the core of the craft. I've never had a problem with it burning anything vital in the extremely brief time its jet touches the core of the craft. And vertical alignment is not an issue.

For asparagus or onion designs, I try to avoid use of Separatrons altogether: (a) radial decouplers well above the CoM of the booster, and strut(s) holding the bottom end tight, and/or (b) fin at the bottom of the booster, assisting early stability and adding a touch of drag on the outside that makes the booster peel away gently.

Finally, you can build one booster with vertical alignment perfected (maybe aligned to a feature on the surface texture), then alt-click it to copy it to your other boosters.

edit: oh snap. OK Slashy has said much the same thing in a fraction of the word-count :wink:

Edited by Plusck
Link to comment
Share on other sites

1 hour ago, GoSlash27 said:

Plusck,

 More in- depth explanations are always welcome :D

Best,
-Slashy

Very kind of you :D

However, I forgot to mention the other option to obtain vertical symmetry: use mirror symmetry.

It's a bit finicky, but you need to use the R (switch between radial and mirror) and F (switch between parent part and craft) key bindings.

Basically, you should start by building a single booster on one of the four cardinal points around the vessel. Then use R and F to place the separatrons with mirror symmetry on the booster itself. Then go back to radial, craft symmetry and grab the decoupler to place pairs of the booster assembly on the craft.

If that doesn't work right, start by building your boosters as normal, and stick a separatron on it at the right place. Then make sure that your craft has an open node at the top. Remove and set aside the engine and any fuel tanks below the one which attaches to the decoupler. Then take off the remaining upper stump of booster and attach it to the top of your craft. Re-attach the separatron booster as a pair using radial symmetry (key R). Then once you're done, place it back on the radial decoupler and reattach the bottom section you set aside earlier.

Finally, you can do much the same thing by building the booster separately and saving as subassembly or as a separate craft that you then "merge" in. Again, the part of the booster that attaches to the radial decoupler needs to be the "operative" part, i.e. root part of the saved vessel that you merge in, or part attached to the root part that you hive off to save as subassembly.

Edited by Plusck
Link to comment
Share on other sites

3 hours ago, Teekin said:

A lot of people recommend Editor Extensions Redux, but that doesn't actually provide for vertical snap, but rather allows you to align things on the vertical axis, but only to the center of the parent module.

Actually there is two way to do it with EEX:

1.build with symmetry then strip it (SHIFT+ALT+Click), adjust staging sequence and fuel flow.

2.Master snap. LCONTROL+Click to select master part, hover over a part and hit V/H to snap it vertically/horizontally relative to the master part. Click on a empty space to deselect master part.

Link to comment
Share on other sites

I'm having trouble understanding what the problem is, i.e. why is this even an issue, and why do editor extensions or other mods even enter into the discussion?  Symmetry works just fine with asparagus, I'm using it all the time.  I'm wondering whether I'm misunderstanding the OP's problem?

On 12/3/2017 at 2:41 AM, Teekin said:

So, of course I need a bunch of sepratrons on my 6 outer rockets in my asparagus staging. I have however found it impossible to make them actually symmetric on the vertical axis.

I'm confused-- why is this a problem, and why do you need vertical snap?

If I'm understanding correctly, you're building an asparagus-staged rocket with sixfold radial symmetry around the central core, yes?

So... that means everything is sixfold symmetry.  Right?  So you don't need vertical snap because everything's part of a single sixfold symmetry group, so that keeps the vertical placement of every symmetrical part rigidly and perfectly aligned with its symmetry counterparts.  Building an asparagus rocket looks like this:

  1. Build central core.
  2. Set radial symmetry mode to six-fold.
  3. Attach radial decouplers to core.  (There are six of them in one symmetry group.)
  4. Attach fuel tanks, engines, etc. to the radial decouplers.  (Still sixfold symmetry.)
  5. Attach sepratrons to the radial stages.  (Still sixfold symmetry).
  6. Do the usual tinkering with the staging UI to split each of your group-of-six items into three separate stages (I'm assuming you're ditching your radial stages in pairs).  You do this once for the radial decouplers and once for the sepratrons.
  7. Set up asparagus fuel flow (either by adding fuel ducts, or by enabling crossfeed on the radial decouplers.)
  8. Done!

Everything works just naturally and automatically in the stock vehicle editor.  No need to have any special editor mods installed.  No need for vertical snap, or working with the translate/rotate widgets at all (unless you need to fine-tune the position of something manually).  It "just works."

Clearly you're having some difficulty with this, but I'm having trouble understanding from your description where you're encountering issues.  Can you elaborate?  Which of the above steps is causing problems?

Link to comment
Share on other sites

6 minutes ago, Snark said:

I'm having trouble understanding what the problem is...

It sounds very much like OP is placing pairs of separatrons on the boosters, one on each side.

Incidentally, if you try placing boosters with sixfold symmetry, will that not make it impossible to set fuel flow correctly with crossfeed enabled? Or require you to place each fuel duct singly? Personally, I always do it with twofold and alt-click to copy/paste each pair.

Link to comment
Share on other sites

35 minutes ago, Plusck said:

It sounds very much like OP is placing pairs of separatrons on the boosters, one on each side.

Ah, okay.  Well, if that's the case, that's not an asparagus problem, that's a general radial symmetry problem.  I rarely encounter this in my own play, mainly because 1. I rarely use sepratrons, and 2. in those rare cases where I do use them, I only put one per booster, not pairs.

But if I were to want to do that, I'd just make the sepratrons radially symmetric around the booster rather than around the ship.  Problem solved.  (Or, even more simply, just visually align them against some bit of texture on the parent, as has been suggested here.)

35 minutes ago, Plusck said:

Incidentally, if you try placing boosters with sixfold symmetry, will that not make it impossible to set fuel flow correctly with crossfeed enabled?

Actually, quite the opposite:  it makes it impossible not to set fuel flow correctly.  The fuel flow will be perfectly correct by default, automatically.  You don't need to tinker with the fuel flow at all:  it just automatically does exactly what you want.

Why does this work?  Because of the automatic "stage offset" for fuel flow.  The fuel flow priority of every tank is actually composed of the sum of two components:

  • A "stage" component.  This is not under the player's control.  It equals the number of the stage in which the tank is located, multiplied by 10.
  • A "manual" component.  This is what the player manually adjusts by clicking the +/- buttons to adjust priority.  It adjusts in increments of 1, and can be positive or negative.

The important thing to understand is that the stage component is automatic, and automatically re-adjusts itself whenever the part's "stage number" changes.

So, for example, say you add six radial tanks, sitting on six radial decouplers, all with sixfold symmetry.  They will all have equal fuel flow priority.  However, as soon as you use the staging UI to break the decouplers into three separate stages... that will automatically update the fuel flow priority of all the tanks.  And it does it in exactly the way you would want:  the first-jettisoned tanks will have the highest priority.

It works perfectly.  And it even works together with the manual component exactly how you'd want.  The manual component keeps its sixfold symmetry.  So, for example, suppose that each of your radial boosters has two fuel tanks stacked vertically one atop the other, and you want to make it so that the bottom tank drains first.  Simple!  Just click the "+" button for the bottom tank, and you're done.  All six of those bottom tanks will have a +1 relative to the six top tanks, so each bottom tank will drain before its corresponding top tank.  But because the manual adjustment is just a +1 whereas the stage adjustment is +10 (per stage), that means that each pair of boosters will completely drain (both top and bottom) before the next pair of boosters starts draining at all.

In short, it automatically does exactly what you want.  It's a brilliant piece of game design-- IMO they totally nailed it, I'm very impressed.

 

35 minutes ago, Plusck said:

Or require you to place each fuel duct singly?

That it does, if you use fuel ducts.  Ever since they gave us the fuel-priority options and crossfeed-enabled decouplers, I mostly don't bother with fuel ducts anymore, because they're tedious to add and easy to accidentally get wrong.  The fuel-crossfeed thing works automatically with a minimum of hassle, so I nearly always use it now.

That said, I  do occasionally use fuel ducts in special cases.  And I used them all the time, before the fuel-crossfeed approach was available.  And, yes, it's kind of tedious to place the fuel ducts manually.

However... personally I would far rather manually place the fuel ducts than manually place all the entire boosters as separate symmetry groups.  I find the latter to be an impossible hassle, much worse than placing the fuel ducts manually.

My reasons for that in spoiler section, since it's getting away from the topic.  (I'm not trying to claim that my way is "better"-- clearly there are folks who prefer it the other way.  Just that this way works better for me, personally.)

Spoiler

So, let's consider building an asparagus rocket, using fuel ducts to handle the fuel flow.  There are a couple of ways to do this:

  • Option 1:  The N radial boosters are all in one single symmetry group.  Need to place N fuel ducts manually.
  • Option 2:  The N radial boosters are in N/2 different symmetry groups.  Need to place fewer fuel ducts manually, since they benefit from symmetry.

I overwhelmingly prefer option 1 to option 2.  My reasons for this:

Rockets, in my experience, need tinkering.  Getting the rocket stability "just so" takes a certain amount of trial-and-error.  Even if I get it "right" the first time, I may need to change the design for reasons unrelated to performance-- e.g. I pick up an extra contract and need to add some additional components to the ship, or something.

The boosters themselves are highly "consequential".  They're giant, they're massive, they exert heavy thrust.  It's really important that they be very precisely aligned and balanced.  And they need frequent editing-- I may need to add some components, or change the fuel amount, or adjust their exact positioning.  They need this frequent editing precisely because they're so consequential.

So, for the boosters:  the fact that they're "consequential" means two things.  First, I have to edit them fairly frequently after initial placement and during rounds of testing.  Second, it's important that I get the alignment exactly precisely right every time I move them.

Overwhelmingly, the easiest way to slay both of those dragons is simply to put the radial boosters all in one symmetry group.  That keeps them always rigidly, precisely aligned with each other.  And if I need to add or remove any pieces, I only have to do it once, not try to duplicate the actions across many symmetry groups.

Whereas, in the case of fuel ducts:  those are trivially inconsequential.  Relative to the mass of the rocket itself, they're tiny to the point of utter insignificance.  They have very low mass, and very low drag.  And they don't exert any thrust.  As long as they're approximately (i.e. mouse-and-eyeball) symmetrical, they're good enough-- a few centimeters of vertical positioning error one way or the other won't make any difference to the ship.  And once they're placed, they don't need tinkering, generally speaking:  as long as they go from the correct tank to the correct tank, that's all they need.

I've tried it both ways, in the early stages of my KSP career.  I quickly concluded that, for me at least, it was tremendously less hassle to set up the fuel ducts one-by-one than it was to split my asparagus stages into separate symmetry groups.

In any case, it's now a mostly moot point for me anyway, since fuel ducts are now largely superfluous and I can quickly/simply build an asparagus ship without any fuel ducts at all.  It's great.  :)

 

Link to comment
Share on other sites

4 hours ago, Snark said:

I'm having trouble understanding what the problem is, i.e. why is this even an issue, and why do editor extensions or other mods even enter into the discussion?  Symmetry works just fine with asparagus, I'm using it all the time.

Correct. EEX is not more than a 'quality of life' mod, that allows the player to do exactly that same that can be done in stock, just in a different way. Not much different but may be preferred by the player and, if he is dog it often, can become significant for his enjoyment of the game.

In any case, the OP mentioned that mod, and apparently was unaware of one or two of its functionalities.That info may be useful for him to decide to use it or not.

 

4 hours ago, Snark said:

 However, as soon as you use the staging UI to break the decouplers into three separate stages... that will automatically update the fuel flow priority of all the tanks.

That is something I was unaware to be possible in stock(in part because I don't play stock). Was under the Assumption that whatever was placed under symmetry needed to be staged with symmetry.

Link to comment
Share on other sites

48 minutes ago, Spricigo said:

That is something I was unaware to be possible in stock(in part because I don't play stock). Was under the Assumption that whatever was placed under symmetry needed to be staged with symmetry.

Yes, I didn't realise this either because I didn't even think it could work, so never tried it.

That's because you cannot make individual changes to the settings of any item placed using symmetry. So once you've launched your craft, if you change fuel flow by adding +1 priority on one tank, it will do the same thing on all tanks linked via symmetry (so six of them with sixfold symmetry).

I didn't realise that by splitting those tanks in the VAB, it automatically sets priority to the staging number. Sure, if you add +1 to one of those tanks it'll add +1 to all of them, but they'll keep their different stage-based multiples of 10 for fuel flow priority.

Link to comment
Share on other sites

3 hours ago, Spricigo said:

That is something I was unaware to be possible in stock(in part because I don't play stock). Was under the Assumption that whatever was placed under symmetry needed to be staged with symmetry.

Yep, turns out that staging is the one thing that symmetry groups don't enforce.  You can split the staging with no trouble at all.

2 hours ago, Plusck said:

That's because you cannot make individual changes to the settings of any item placed using symmetry.

Yep.  Except for staging.  :P

2 hours ago, Plusck said:

I didn't realise that by splitting those tanks in the VAB, it automatically sets priority to the staging number. Sure, if you add +1 to one of those tanks it'll add +1 to all of them, but they'll keep their different stage-based multiples of 10 for fuel flow priority.

Exactly.  It's the sort of thing that I know I probably wouldn't have thought of, if I'd been designing the feature myself... which is part of why it impresses me so.  "Just make everything work the way one would expect."

I guess I happened to notice it right off the bat, myself, because I was already in the habit of splitting symmetry groups into separate stages.  If one is in the habit of doing that, the staging behavior of fuel flow becomes a lot more obvious.

So I guess the real "discoverability hole" here is the fact that "you can split symmetry groups by stage."  I can totally see how someone could play KSP for years without realizing that.  I try to think "how did I discover or find out that feature, myself" ... but so much water has gone under the bridge since then that I honestly have no clue how or when I first found this out.  Dunno if I discovered it myself accidentally, or read about it in the forum, or what; it's just one of those things that I've "always done".

Link to comment
Share on other sites

Heh, I actually think the reasons for my myopia on this are tied to when I really started with the "main game" (1.0.5 I think). You could do things indivdually to parts (like lower landing gear), but then 1.1 (I think) broke that and since then I've been fixated on the "placed in symmetry = all do the same thing".

Still, to be perfectly honest, when I go beyond 2x symmetry it's because I'm creating an unholy monstrosity that by all rights shouldn't fly. Not even Krikkit One. More like Krikkit 0.9.1.v3. So I'm probably not looking for elegant solutions at that stage.

Link to comment
Share on other sites

On 12/3/2017 at 5:41 AM, Teekin said:

So, of course I need a bunch of sepratrons on my 6 outer rockets in my asparagus staging. I have however found it impossible to make them actually symmetric on the vertical axis.

How do you do it?

First off, I don't use Sepratrons. I don't actually remember the last time I used them. In those rare instances that aerodynamics doesn't do the job for me of keeping the dropped boosters heading away, I help it along with the smallest fins available twisted slightly outward.

ksp_sepratron_fins.jpg

To align them perfectly vertically with each other, I use the Move Tool (Hit '2' to activate it) with Snap turned ON, and align them vertically which is very easy with snap ON. If this makes them sink into the ship, I just turn snap OFF and pull them out a bit, because doing so will retain vertical alignment. The same technique should work fine for your sepratrons. Incidentally, to rotate those fins I use the rotate tool (Hit '3' to activate it).

Editor Extensions is a great mod, but I almost never see the need to install it anymore.

Link to comment
Share on other sites

14 hours ago, Plusck said:

Heh, I actually think the reasons for my myopia on this are tied to when I really started with the "main game" (1.0.5 I think). You could do things indivdually to parts (like lower landing gear), but then 1.1 (I think) broke that and since then I've been fixated on the "placed in symmetry = all do the same thing".

Heh, fair 'nuff.  But FWIW, I'm pretty sure that this feature (i.e. "stage-breakable" symmetry groups) has been around since forever.  Certainly since before 1.0, because I know I was using it in the crappy old aero all the time, because the old aero was especially friendly to asparagus (since there wasn't any drag penalty for building "fat" rockets).

Link to comment
Share on other sites

On 12/4/2017 at 12:29 PM, Snark said:

It adjusts in increments of 1, and can be positive or negative.

Unrelated to discussion but feel like chiming in - increments of 1 normally, increments of 10 holding the modifier key (in windows ALT).

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...