Separating two vessels in suborbital: Still unable in KSP?

[juvilado]

Hi, im not sure if a core problem KSP had in earlier versions is still in 1.1.3.

In earlier versions we couldn't separate one vessel from another on suborbital and go on ascending with one while the other slowly descended. There was a point (i think it was related to distance between them) where the non active vessel just vanished. Is it already solved?

[ForScience6686]

No.  The distance did increase to some 20km or so, not sure of the exact distance.  So it is better, but I don't see it ever going away.

[juvilado]

Sadly, it is an obstacle for an entire line of rocket designs...

[Signo]

The "active separation" between crafts is now based (as far as I understand) on atmospheric pressure  - when pressure is below 1% of total sea level the crafts are allowed to be. 

So if you separate the crafts above 23000m on Kerbin you will be able to keep both flying. 

[ForScience6686]

There is always more than one way of completing a task.  This game is all about engineering challenges.  Not sure of what exactly you are going for here though.  But there are a lot of bright people here that can help figure out a solution.

Beyond that, there's a mod for just about everything...

[juvilado]

4 minutes ago, Signo said:

The "active separation" between crafts is now based (as far as I understand) on atmospheric pressure  - when pressure is below 1% of total sea level the crafts are allowed to be. 

So if you separate the crafts above 23000m on Kerbin you will be able to keep both flying. 

You mean now i can decouple the 1st stage at 23Km, activate the parachutes and trust in its safely landing for further recovering while im ascending with the upper stages? that couldn't be done before, as the 1st stage just used to vanish...

[ForScience6686]

Pretty sure it will still vanish once out of physics range, especially since it is in atmosphere.  Anything below a certain altitude threshold, dependant on body, will be eliminated.

[Reactordrone]

19 minutes ago, juvilado said:

You mean now i can decouple the 1st stage at 23Km, activate the parachutes and trust in its safely landing for further recovering while im ascending with the upper stages? that couldn't be done before, as the 1st stage just used to vanish...

You have to be in command of the landing part until it touches down and then switch back to the orbital section. You can usually manage to control the apoapsis of the orbital section by locking off fuel tanks but you're never going to get a particularly low apoapsis due to the time it takes to land the first stage.

[Signo]

1 hour ago, juvilado said:

You mean now i can decouple the 1st stage at 23Km, activate the parachutes and trust in its safely landing for further recovering while im ascending with the upper stages? that couldn't be done before, as the 1st stage just used to vanish...

Actually, to be safe, the "second stage" must be outside the atmosphere while landing the "first stage" - i.e. give you first stage an ascending path and an attitude that could keep it above 23000m while you manage orbit with your "spaceship two".

However I am pretty sure there are several different ways to complete the mission. 

[Spricigo]

There is also a mod,  if you feel stock mechanics not good enough.  FMRS

 

[pincushionman]

I'd like to point out that ships despawning at >1% atmosphere pressure while not in focus isn't "an issue to be resolved," it was a deliberate design decision. Aerodynamics calculations are costly, and calculating for what is almost always discarded stages frees the calculation for what's actually important - the active vessel.

Now, in 1.1, the constraints that drove this decision are less severe - individual vessels can have their own physics threads, and there has been a general improvement in performance. So it may not be out of the question to re-think this, at least for items that require no control, like those with parachutes.

Edited August 30, 2016 by pincushionman

[Corona688]

On the other hand, increasing KSP's performance requirements isn't always viable.  This may be mod territory.