[0.24] If a Booster Has Enough Parachutes On It, Count it as "Recovered"

[r4pt0r]

Snip-

So you go either SSTO, or you lose money.

i wouldnt say lose, id say spend extra. its a business expense not a loss.

[Strikerklm96]

For parts of your ship that fall inside the atmosphere, you should either get some % back always, or get some % back if there is a parachute on it.

[cpast]

For parts of your ship that fall inside the atmosphere, you should either get some % back always, or get some % back if there is a parachute on it.

Why should you get some back at all?

[ixolate industries]

You should get some funds back so long as your booster has enough parachutes to land safely and doesn't experience reentry heat or land on a mountain. Those parts wouldn't just vanish normally (excluding reentry) and you do deserve a bit if you put in money to recover them.

To those of you who land your boosters vertically; Why? Putting parachutes on just one side would allow you to land horizontally with a lower center of mass and less chance of tipping over. A safe landing may not be a unlikely as some believe.

[Jouni]

To those of you who land your boosters vertically; Why? Putting parachutes on just one side would allow you to land horizontally with a lower center of mass and less chance of tipping over. A safe landing may not be a unlikely as some believe.

It's not a matter of belief, when you can easily try it yourself. Build a launcher for some nontrivial payload (100 tonnes, for example), and see what it takes to reliably recover each spent stage.

[Technical Ben]

Powered landings are very successful...

With the new vernor rockets, this is more possible:

http://youtu.be/sSF81yjVbJE

Currently KSP will destroy both those reusable stages if you attempt it in game...

[edit]

WAIT... What? I just tested it... KSP now lets you fire ships out on ballistic trajectories in the atmosphere, and keep them alive?!

I'm SOOOO making that grasshopper reusable rocket now... Although I still need to get perfect timing between craft, as it's going to drift quite some way without power (as it's outside sim range).

Edited July 20, 2014 by Technical Ben

[JAKKAT]

Title says it all.

Another reason is that it's annoying to see your spaceplane just vanish when you fall out of it.

[technicalfool]

From what I'm aware there's a couple of people working on mods to fudge their way around the issue. I've had a little go myself and managed to make a little headway, however finding the right fudge factor to decide whether the vessel would be going slow enough to land safely versus be damaged (and by how much) versus be destroyed, is not actually all that trivial.

I would suggest "watch this space". Stuff is afoot.

[tntristan12]

I think they could just run physics for 're-entering objects with some limitations. Think about when objects are 're-entering. In the vast majority of times it is a dropped lower stage on ascent, a payload module that is 're-entering with the controlled vessel, or an upper stage that is 're-entering after some on-orbit maneuver. In all three of these cases the relative distances and velocities are small.

What I would do? If the controlled vessel is in the same SOI as the 're-entering object, pop up some kind of notification saying "--- is 're-entering Kerbin's atmoshphere." It doesn't have to be a full sim, but could look to see if any parachutes are deployed and look at the average heat tolerance to determine whether the object would burn up or not. If there are no deployed parachutes (as in the vast majority of upper stages) or there are no heat shields on board then the object is destroyed and disappears like it does now. If there are parachutes then the drag to weight ratio is analyzed to determine the velocity at landing. Then loop over all parts on the object to check if the impact speed is greater than that at which the object would survive. If so, then plop the object down onto kerbin and allow the player to recover it later.

That's how I'd do it. Personally I think anything is better than the current model. Especially now that there is no reason you shouldn't be able to recover things with enough parachutes on them.

[cpast]

I can think of such a reason - letting you recover all stages by slapping on parachutes means there is no longer such a need to minimize staging. It's harder to use fewer stages; doing so should be rewarded by any sensible budget system. I've still never seen a very good reason upper stages *should* be recoverable.

[tntristan12]

I can think of such a reason - letting you recover all stages by slapping on parachutes means there is no longer such a need to minimize staging. It's harder to use fewer stages; doing so should be rewarded by any sensible budget system. I've still never seen a very good reason upper stages *should* be recoverable.

Parachutes still cost money, and the bigger your stage the more parachutes you need. If you have the expendable income why should the game restrict you from doing what's obvious? As it stands there is no reason to instanuke anything that's in the atmosphere not being controlled, but would otherwise survive just fine.

Besides, what about manned return pods? Are you telling me that the only reason one pod survives and the other doesn't is because one had the focus on it and the other didn't?

[Kegereneku]

Anything that isn't focused on by the player and is in the atmosphere outside the 2km sphere where physics is computed, is Erased.

The game work like that certainly because it would be to complicated to keep applying aerodynamic-physics to many object too far apart.

For a time KSP had problems when computing physics for rocket too far from the "point of origin", it was solved by making this origin move with players-focus.

The best I can suggest to get around this and recover at least the last stage is to achieve orbit fast and higher, and get back to the falling stage before it reach the atmosphere.

Edit : However as a suggestion I wonder if it wouldn't be possible to make a special part that get another "sphere of physic" for as long as it take for it to reach a stable situation like "landed" or "splashed down"

Edited July 21, 2014 by Kegereneku

[Seshins]

Or it could just be a random figure say 40-90% of the parts value is recovered to simulate unforeseen re-entry damage.

[Jouni]

We'll probably get multi-threaded and/or GPU accelerated physics engine eventually, and that will solve the problem. Except for one thing. We obviously can't time warp when the physics simulation is running, which can get quite annoying, if the game simulates objects flying in an atmosphere far away from the active ship.

Meanwhile we'll just have to wait.

[Kegereneku]

I'm really not in favor of an abstract "just act as if I recovered that".

I would prefer to wait until the game become stable enough that it can try to apply physics to those part at least until they land/splash, after what the game would go back to "on-rail".

[Clockwork_werewolf]

Parachute recovery, as technicalfool said is not simple. Firstly what part is landing when it reaches ground? Is it a high impact part like landing legs or a very low impact part? How does the game know which part it is landing on without fully physics calculating it? Are the parts ripped apart by the parachute openings? Since recovery savings are relative to distance from KSP, where will the parts land? What angle landscape are the parts landing on? If they are landing on a 45 degree mountain then in reality they would tumble and possibly be destroyed.

You could in fact set up some fudges to ignore some of these questions and simplify others. You could assume always flat surfaces. You could average all part impact tolerances and use that as impact tolerance. Ignore parachute opening force. You could do a simple trajectory calculation that ignores atmosphere to work out landing site. Lastly use all this to work out if it survives and from landing location cost saved. Automatically recover costs rather than landing the parts so that you don't need to simulate its landing.

You could end up paying more for parachutes than you get back from recovery though at which point the whole mod is a bit useless. I'm having fun trying to get costs down or make things reusable. Good luck to those working on mods though, I know I have at least one friend trying these mods out.

[technicalfool]

Edit : However as a suggestion I wonder if it wouldn't be possible to make a special part that get another "sphere of physic" for as long as it take for it to reach a stable situation like "landed" or "splashed down"

Detecting whether a vessel is on rails and is about to be destroyed due to being too low in an atmosphere is not the hard part. Or at least, not the hardest part. From there, it's easy enough to check that the vessel's current celestial body is Kerbin, and force the game to do a "Vessel.load()" in order to count the number of parachutes. It would be unnecessary to track the vessel with full physics all the way to ground level.

The trick is, finding a fudge factor that's accurate enough to say "well this vessel would be doing X m/s at sea level", and have it accurate against what the vessel would actually be doing at sea level if you were to switch to it and follow it down. Then you have to fudge the amount of damage that the vessel might suffer. Plus the various other things already mentioned such as coming down in a mountainous region, fudging the numbers accurately is the name of the game here.

Edited July 21, 2014 by technicalfool

[Tuareg]

Anything that isn't focused on by the player and is in the atmosphere outside the 2km sphere where physics is computed, is Erased.

The game work like that certainly because it would be to complicated to keep applying aerodynamic-physics to many object too far apart.

but it doesnt need any physics to be calculated on falling back stuff, it just need simple decisions to be made explained by many above. its just incompetency or they simply dont care enough to write a 10 lines code...

[Jouni]

but it doesnt need any physics to be calculated on falling back stuff, it just need simple decisions to be made explained by many above. its just incompetency or they simply dont care enough to write a 10 lines code...

Determining whether something can land intact requires full physics simulation. The workarounds mentioned in this thread (and in many others) are bad game design, because they make recovering ships easier, when the player isn't looking.

[Tuareg]

Determining whether something can land intact requires full physics simulation. The workarounds mentioned in this thread (and in many others) are bad game design, because they make recovering ships easier, when the player isn't looking.

yes, because simply erasing the parts you dont look after continuously is the right mechanism... valid. really. i want a BIG LOL smile!!! it doesnt need ANY physics just like 90% of this game already doesnt have.

[Jouni]

yes, because simply erasing the parts you dont look after continuously is the right mechanism... valid. really. i want a BIG LOL smile!!! it doesnt need ANY physics just like 90% of this game already doesnt have.

Booster recovery isn't such a big deal. We'll probably get it properly implemented in a year or two, when KSP can handle multi-threaded physics. What we don't need are poorly justified, easily exploitable temporary mechanisms for it.

[Kerbart]

Title says it all.

Another reason is that it's annoying to see your spaceplane just vanish when you fall out of it.

Whenever you find a shortcoming in the game, ask yourself a few questions.

• Why did they do it that way?
  
• What would happen if that limitation wasn't there
  
• Would I like the new version?

It is safe to assume that in-game limitations are there for a reason, and not put in by the developers to troll us. For recovery it is indeed annoying that individual parts that spawn off your ship (booster rockets, etc) simply vanish. Ok, so let's run those four boosters in their own little physics bubble. Surely it will slow down gameplay, but hey, now you can build recoverable boosters. Ain't that cool!

And then you launch a whackjobian contraption that dumps 36 first stage boosters in the first 2000m of your ascent. Frame rates crawl to a halt...

Wait! It gets worse! Two of those boosters crash into each other, causing an explosion which spawns off 60 parts splattering all over in all directions, and of course crashing into other spent boosters. A chain reaction follows and now there are 684 parts flying around that the game has to keep track off, each in their own little physics bubble.

"Well don't put them in different bubbles"

How would you merge the bubbles? How much calculation time is allowed to be spent on that?

"Simply increase bubble size"

To what? 100km? Whatever the size is, it's always going to be not enough and it's quickly going to be too big for your computer to handle.

The problem with most suggestions is not that they're bad; they work very well for the intended scenario. The problem the developers are facing is that they have to make their code work for every scenario we, as users, can come up with. And we come up with a lot... As a result we end up with a lot of limitations that seem arbritary, yes even silly. But it's pretty safe to assume they're there for a good reason.

Edited July 21, 2014 by Kerbart

[Kegereneku]

As true as is your speech you forget a very basic way to keep this from happening :

Limiting the sphere bubble to parts that have a control-part like the ones which were specifically done to be used as launcher.

Sure, some thoses with absurdly powerful PC will try to challenge that but at least it won't be accidental.

In any case like Jouni I wouldn't like a poor abstract recovery system that do not actually make use of KSP physics engines.

.. and I'm not saying that because someday I hope to make a SpaceX main stage with landing gear.

[Tuareg]

As true as is your speech you forget a very basic way to keep this from happening :

Limiting the sphere bubble to parts that have a control-part like the ones which were specifically done to be used as launcher.

Sure, some thoses with absurdly powerful PC will try to challenge that but at least it won't be accidental.

In any case like Jouni I wouldn't like a poor abstract recovery system that do not actually make use of KSP physics engines.

.. and I'm not saying that because someday I hope to make a SpaceX main stage with landing gear.

but you like a poor abstract orbiting system that do not actually make use of KSP physics engines

[Kerbart]

As true as is your speech you forget a very basic way to keep this from happening :

Limiting the sphere bubble to parts that have a control-part like the ones which were specifically done to be used as launcher.

Sure, some thoses with absurdly powerful PC will try to challenge that but at least it won't be accidental.

Yes, I did not consider that option. BUT... this would mean that every part with a control unit would constantly be inside an "active" physics bundle. The minute you say "well deactivate them after landing" you're just going to get other complaints by users who find that their plan of bomb-dropping probes all over the place isn't working.

Ok, so we keep 'm active*. Keep in mind that you're stuck in Physics Acceleration until all of those spawned off units have been resolved. And since you're running a handful of them (or more), Physics Acceleration at maximum speed probably means realtime. At best. More likely your simulation will be running at half-speed. Or quarter speed. "So what?" Well, you're going to be stuck with that for the full 500m those items are floating down on their chutes at a leisurely 7.5 m/s - That's about 1m gametime, and if you're running at quarter speed that's 4m of real world time. And that assumes you can keep track of them until they land and hit "recover" to speed things up. Let's hope your launch vehicle doesn't need attention in the meantime.

I'm not saying it's impossible. But it involves adding a lot of features to make it happen, possibly dramatically impacting framerate performance. It's a lot easier to say "design wisely. Boosters spent are boosters spent and won't be recovered. If you don't like that, start working on those SSTO skills"

What I do suspect in future versions is that some boosters will have some auto-recover flag. After all, the KD25K description already states "This super heavy booster is designed to be recovered after jettisoning. Once recovered, it is refurbished and refueled for another launch."