The Korolev Crunch.

[Vanamonde]

A phase of most KSP launches. 

[cantab]

It's just neighbourly. Making sure the boosters explode in the air so they don't fall on the ground.

[linuxgurugamer]

Only of the decouplers are improperly placed. Oh, wait. This is KSP, not rocket science

[Superfluous J]

I like to put the tiny fins on my side boosters, rotated one shift-rotation (I think it's 5 degrees?) outward. Makes the boosters fly away in a most satisfying way.

But I know what you're talking about. When my boosters fly inward on separation and miss each other, I feel a bit robbed.

Edited May 20, 2019 by 5thHorseman

[Long Finger]

I like to use Sepratrons. That way your boosters fly off like fireworks and explode in a nice pattern on the ground.

[Snark]

Oh! Saw the thread title, had assumed the thread would be about kerbals' favorite breakfast cereal.

I've always assumed that the reason for this common sight is the presence of the decoupler stuck to the "inside" side of the booster, which generates quite a bit of drag there.

I mostly don't try to do anything about it myself, except in the occasional cases where the ship design is such that there's risk of their hitting the central stack. Doesn't come up often. When it does, I usually use the angled-fin approach that 5thHorseman describes.

[Xurkitree]

If this happens and the it crashes into my ship, I just offset them far enough that they dont crash anymore. Looks weird, but it does the job.

[Geonovast]

I just imagine the shockwave from the explosion gives you an extra 0.1 m/s of dV.

I do try to avoid it now though.  Got into the habit when I started building shuttles.  Ejection management there is pretty crucial.

[RealKerbal3x]

Just now, Geonovast said:

I do try to avoid it now though.  Got into the habit when I started building shuttles.  Ejection management there is pretty crucial.

Yes, in my various attempts to build shuttles, I've learned that if you lose your wings at booster separation, you will not come back from space today.

[Mikki]

...I often realize i messed up "something" after hitting the launch button and

a: lost control about basically everything or -
b: feel the first stage pushing weirdly on the unluckily dettached upperstage or -
c: hit frantically "abort" if i`ve built in any launchescape system or -
d: drop my jaw in wonder about the beauty of prematurely staged uncontrolled solid boosters or -
e: close said jaw when watching said boosters colliding with the rest of my beloved rocket or -
f: feel amazed about the huge fireball where the rocket was supposed to fly seconds before or -
g: get uncomfy while significant parts of my rocket fall off without permission or -
h: launchclaps decide to disengage before any thrust has built up or -
i: wonder why my rocket tips nicely over towards the sea due to excessive ... umm (insert educated guess here) or -
k: ...

...then, i feel in best company visiting this forum. 

Edited May 21, 2019 by Mikki
typo:D

[MisterKerman]

I use 2 outward facing separatrons located at the dry CoM of the spent booster and stage once spent.

[MaverickSawyer]

I usually put the decoupler further up the booster with the displacement widget so that the initial kick is to tip the nose out into the airstream, rather than just kicking the entire booster outwards. They may collide again later, but it's usually more than a kilometer behind the rest of the rocket... perfectly safe.

[Pthigrivi]

1 hour ago, MaverickSawyer said:

I usually put the decoupler further up the booster with the displacement widget so that the initial kick is to tip the nose out into the airstream, rather than just kicking the entire booster outwards. They may collide again later, but it's usually more than a kilometer behind the rest of the rocket... perfectly safe.

This is what I do. I find it doesn't have to be very high up on the booster, just forward of its dry COM so it kicks out with a bias. If its up too high they tend to rotate around and collide at the engine bells. I'll occasionally use sepratrons the same way on really huge boosters. 

[MaverickSawyer]

1 hour ago, Pthigrivi said:

This is what I do. I find it doesn't have to be very high up on the booster, just forward of its dry COM so it kicks out with a bias. If its up too high they tend to rotate around and collide at the engine bells. I'll occasionally use sepratrons the same way on really huge boosters. 

Yep. But, with seperatrons, you can usually trim the fuel supply down to a fraction of normal. you don't need five seconds of burn time. Even half a second is usually enough.

[Superfluous J]

3 hours ago, MaverickSawyer said:

I usually put the decoupler further up the booster with the displacement widget so that the initial kick is to tip the nose out into the airstream, rather than just kicking the entire booster outwards. They may collide again later, but it's usually more than a kilometer behind the rest of the rocket... perfectly safe.

I find just placing the booster as far down the decoupler as I can is enough, and in those rare cases it's not the fin trick is all I need.

[katateochi]

7 hours ago, Snark said:

Oh! Saw the thread title, had assumed the thread would be about kerbals' favorite breakfast cereal.

Squad really needs to step up their merchandising game; I'd buy Korolev Crunch!

8 hours ago, Snark said:

I've always assumed that the reason for this common sight is the presence of the decoupler stuck to the "inside" side of the booster, which generates quite a bit of drag there.

That could be a factor. Also, there was a thread a day or two ago, about the aerodynamic properties of the slanted nose cone. That suggested that the slant is more than just aesthetic and does actually have the aerodynamic impact you'd expect from the slant. So in this case that could also be pushing the boosters together.  If one was prepared to sacrifice looks, and put the cones on the "wrong" way, facing out, then maybe that alone might give a clean separation? 

[Snark]

7 minutes ago, katateochi said:

Squad really needs to step up their merchandising game; I'd buy Korolev Crunch!

Yeah, but don't eat too much or your breakfast may achieve escape velocity. 

8 minutes ago, katateochi said:

Also, there was a thread a day or two ago, about the aerodynamic properties of the slanted nose cone. That suggested that the slant is more than just aesthetic and does actually have the aerodynamic impact you'd expect from the slant. So in this case that could also be pushing the boosters together.

Except that I observe the Korolev Crunch even when not using the slanted cones.  (I tend to just use the basic nose cone on my SRBs, since they get jettisoned before I'm going seriously hypersonic anyway.)

[Chryssalid 8492]

Generally I just use seperatrons on the slanted nose cones to prevent then whacking the ship.

[Kerbart]

8 hours ago, RealKerbal3x said:

Yes, in my various attempts to build shuttles, I've learned that if you lose your wings at booster separation, you will not come back from space today.

Oh, you will get back. It’s more that the landing will be a once-in-a-lifetime experience.

[Loskene]

6 minutes ago, Kerbart said:

Oh, you will get back. It’s more that the landing will be a once-in-a-lifetime experience.

Haven't lived until you've tried to recover a one-winged shuttle. It's enough to make you start designing your launchers so that at the very least, both wings will get taken out in a booster strike.

[Chryssalid 8492]

9 hours ago, RealKerbal3x said:

Yes, in my various attempts to build shuttles, I've learned that if you lose your wings at booster separation, you will not come back from space today.

Shenanigans You just need a boat load of RCS and a little luck

 

Edited May 22, 2019 by Chryssalid 8492

[Kerbart]

10 hours ago, Loskene said:

Haven't lived until you've tried to recover a one-winged shuttle. It's enough to make you start designing your launchers so that at the very least, both wings will get taken out in a booster strike.

https://theaviationist.com/2014/09/15/f-15-lands-with-one-wing/

[KerikBalm]

On 5/20/2019 at 2:11 AM, 5thHorseman said:

I like to put the tiny fins on my side boosters, rotated one shift-rotation (I think it's 5 degrees?) outward. Makes the boosters fly away in a most satisfying way.

^This^

Aerodynamic separation forces are super reliable, they are often what cause the crunch to start with, so a solution to the crunch is to alter the aerodynamic forces.

Of course, sepratrons can be cool too... but 1-2 basic fins are super cheap and lightweight.

[Nich]

I have always found reducing thrust to 10% at separation makes the boosters behave much more nicely and not take out the center stack.

[sgt_flyer]

i generally use various techniques depending on the boosters

one is to use downward facing separatrons (or even RT5s instead of separatrons when the boosters are big enough ^^) close to the core stage on the booster. the resulting assymetry of thrust will make the booster veer nicely away from each other. (don't try this with forward facing separatrons on the outside of the booster, it generally ends with the booster's tail colliding with each other )

another way with two sets of separatrons, is having one set above the dry COM the other below the COM, with the bottom ones configured with less solid fuel, but same thrust - gives a nice two phase decoupling sequence - the boosters go away vertically from the core stage, then once the bottom separatrons are spent, the still firing topmost separatrons make the boosters go in a tumble nose away from the rocket.

Edited May 23, 2019 by sgt_flyer