How should rockets flex?

[Meecrob]

So to sum it all up, the "wobbliness" of KSP1 is the absolute baseline for what us players would consider playable? I'm asking to get a consensus. I agree we are all kinda arguing our own nitpics and its taking us around in circles.

[Dakitess]

KSP1 with a few AutoStrut is fine though I'd like to see something else coming along to avoid the dead-ends, the known issues, the performance hit.

It would really be nice to get something more... "intelligent", being able to deal with long structural assembly that are only because of non-procedural construction. Come on, we all know that 3 tanks stacked are just meant to be one big "rigid" tank. This is why we use AutoStrut to tell the game that yup, this end is structurally connected to this one, without flew in between.

[PDCWolf]

On 7/11/2023 at 1:46 PM, LoSBoL said:

Apart from the 'we want full rigidity' arguments you won't find many people that argue differently, including Nate. What we have now needs to be fixed, it's even in the arguments Nate shared, did you read what pdcwolf shared, it's full of nuances on the 'Nate thinks it's fun' take.

There's a very different profile, as evidenced by this thread, between people that look at wobble as a bug and nuance, versus people that think it's part of the Kerbal experience. When talking about wobble Nate is looking to tune a feature, not to squash a bug. That's why a lot of us are concerned with this matter. There's an even harder divide when you consider the divide to be "wobble is fun" vs "wobble is a bug/nuisance" which are polar opposites.

On 7/11/2023 at 7:30 PM, Meecrob said:

So to sum it all up, the "wobbliness" of KSP1 is the absolute baseline for what us players would consider playable? I'm asking to get a consensus. I agree we are all kinda arguing our own nitpics and its taking us around in circles.

For me, rocket wobble in KSP1 (without abusing autostruts) is already past the limit of what's tolerable. This is different to wobble on wings, which can look correct but is still incorrect in the sense that doesn't respond to any structure-relevant simulation, but rather "did you make long wing with 1 part or many part".

[kdaviper]

17 minutes ago, PDCWolf said:

There's a very different profile, as evidenced by this thread, between people that look at wobble as a bug and nuance, versus people that think it's part of the Kerbal experience. When talking about wobble Nate is looking to tune a feature, not to squash a bug. That's why a lot of us are concerned with this matter. There's an even harder divide when you consider the divide to be "wobble is fun" vs "wobble is a bug/nuisance" which are polar opposites.

For me, rocket wobble in KSP1 (without abusing autostruts) is already past the limit of what's tolerable. This is different to wobble on wings, which can look correct but is still incorrect in the sense that doesn't respond to any structure-relevant simulation, but rather "did you make long wing with 1 part or many part".

Personally, I am conflicted when it comes to this subject. The wobbliness itself isn't fun, but it does present a challenge that is satisfying to overcome. 

I have watched gameplay of Juno where the entire ship is simulated as a rigid body and while that method does offer a clear advantage in predictability and performance, the gameplay seems sterile and boring. 

If there is an alternative method of providing structural feedback that doesn't lead to slithery noodly craft and doesn't take a worse toll on performance I would be unironically interested in seeing it. 

[Alexoff]

On 7/11/2023 at 7:46 PM, LoSBoL said:

Can it be that your assumptions are the cause of the discrepancies? Noone is arguing that rockets should sway in the wind like trees. If that's want you are debating against you might just be tilting at windmills.

As for the 'wobling like in real life', are you maybe taking that to literal? If KSP mimic that literally, you are not going to see wobbling in the game. Could it be that people, when they vote for 'like in real life' expect to see just a little wobbling in the game? 

And what is your opinion? Maybe I'm wrong, do you believe that the developers will manage and do everything tip-top?

[PDCWolf]

7 hours ago, kdaviper said:

 it does present a challenge that is satisfying to overcome.

I look at that challenge the same way I look at most (if not all) life support mods: If you're challenging me to use +1 part in my design to solve the issue (or in the case of KSP1, right click > autostrut) was there really any challenge to begin with?  SRBs wobble? 1 strut from main core into booster nosecone. Payloads wobble? autostrut to heaviest or grandparent. Docked station wobbles? get an engineer out with a single strut.

Sorry, but I fail to see it as a challenge, and continue to see it as a nuisance and an excuse to waste parts and thus performance. A punishment to the player for completing the """"challenge"""".

[cfds]

The real problem with this discussion is that the devs should have had it five years ago. Even looking from the outside, it was clear that the main problem with KSP 1 development was the constant uphill battle against Unity physics. It was a mess of band aids, cludges, and hacks, and tended to break in surprising (and difficult to test) ways. That they still decided to go with it shows that they either did not believe that they could find a better solution or that they actualy believed the idea that KSP is a lolplosion simulator first and foremost. Neither is good news for the more serious players.  Unfortunately, there are probably more than enough people perfectly happy to spend 50€ to spend a few hour crashing stuff around the space center to validate this approach...

[LoSBoL]

On 7/13/2023 at 9:25 PM, Alexoff said:

And what is your opinion? Maybe I'm wrong, do you believe that the developers will manage and do everything tip-top?

I thought I'd shared but I didn't. I vote for a little flex like in real life. With the mindset that that flex would be visible in the game when building unstable builds. I've always assessed KSP's wobbly rockets as feedback and part of the engineering 'Build' part of the game. KSP is Build, Fly, Dream to me. Current wobbling is way to much, as acknowledged.

With that said KSP2 should be able to deliver what KSP1 does as a minimum, and be able to launch monstrosities, in that way an Autostrut feature or join reinforcement feature would be completely fine by me to be able to do so. 

I'm confident in them finding the right solution, they basically have to considering what they need to achieve in the future with massive colony and interstellar builds. They also acknowledged they have to face the performance reality in the solution and act accordingly to have the game playable. Without insights in what is possible in development and how developers take up this challenge I have no base to be dismissive in their abilities. PDCWolf posted a good eleboration in their communication about the wobbly rockets;
 
https://forum.kerbalspaceprogram.com/topic/214187-how-should-rockets-flex/?do=findComment&comment=4301264

 

 

On 7/13/2023 at 6:16 PM, PDCWolf said:

There's a very different profile, as evidenced by this thread, between people that look at wobble as a bug and nuance, versus people that think it's part of the Kerbal experience. When talking about wobble Nate is looking to tune a feature, not to squash a bug. That's why a lot of us are concerned with this matter. There's an even harder divide when you consider the divide to be "wobble is fun" vs "wobble is a bug/nuisance" which are polar opposites.

I think you hit the nail here in explaining the different viewpoints. The polar opposites in this won't convince each other, and it's best to agree to disagree. I can certainly imagine you're concerns.

Edited July 15, 2023 by LoSBoL

[MechBFP]

8 hours ago, LoSBoL said:

think you hit the nail here in explaining the different viewpoints. The polar opposites in this won't convince each other, and it's best to agree to disagree. I can certainly imagine you're concerns.

They are hardly polar opposites. The level of wobble in KSP2 is absolutely a nuisance in some builds, as you can literally make spaghetti rockets right now without them breaking apart. That doesn’t mean a much more appropriate design that still includes flex isn’t desired either. 

[Dakota]

Going to again reaffirm that we see wobbliness as a major issue and the team is actively working towards solutions - both addressing physics bugs that cause instability, as well as having design discussions building off of Nate's comments from the Calvinball Dev Update.

It's an issue that is severely affecting the playability of the game for many people and we recognize that. Nate recognizes that and has been a lead organizer in these discussions to resolve this issue. We're also working with external partners to get more of an understanding of our potential options to address this within the game's engine.

On community fixes - changing physics variables have cascading effects all over the game. Resolving this issue isn't as simple as changing those variables, it's a very complicated process, which we plan to have one of our engineers, David (TriggerAU), dive deep into in a future dev blog/interview, once it's resolved.

[LoSBoL]

27 minutes ago, MechBFP said:

They are hardly polar opposites. The level of wobble in KSP2 is absolutely a nuisance in some builds, as you can literally make spaghetti rockets right now without them breaking apart. That doesn’t mean a much more appropriate design that still includes flex isn’t desired either. 

If you read PDCWolfs elaboration on viewpoints on which I reacted they are absolute polar opposites, you might be making the mistake that the current amount of wobbleness is seen as preferable to anyone, it's not, it's like you say a nuisance, way to much and needs to be corrected, no matter which stance anyone has, that's (probably) agreed upon by everyone.

Edited July 15, 2023 by LoSBoL

[Periple]

I can’t see how there are polar opposites in this discussion. There are different opinions about how much flex and wobble there ought to be, ranging from “none” to “some but a fair bit less than now.” I’m quite sure there’s a compromise there that will make most people happy, and that the technical problems are surmountable.

[MechBFP]

20 minutes ago, LoSBoL said:

If you read PDCWolfs elaboration on viewpoints on which I reacted they are absolute polar opposites, you might be making the mistake that the current amount of wobbleness is seen as preferable to anyone, it's not, it's like you say a nuisance, way to much and needs to be corrected, no matter which stance anyone has, that's (probably) agreed upon by everyone.

For any serious gameplay, yes. 
It is fun for a few minutes though to purposefully abuse it and make dumb things lol. 

[pipe]

On 7/13/2023 at 6:43 PM, kdaviper said:

Personally, I am conflicted when it comes to this subject. The wobbliness itself isn't fun, but it does present a challenge that is satisfying to overcome. 

I have watched gameplay of Juno where the entire ship is simulated as a rigid body and while that method does offer a clear advantage in predictability and performance, the gameplay seems sterile and boring. 

If there is an alternative method of providing structural feedback that doesn't lead to slithery noodly craft and doesn't take a worse toll on performance I would be unironically interested in seeing it. 

I disagree. It was never fun for me to have to deal with rockets that act like they're made of gelatine, nor was it satisfying when I finally got them to behave like actual rockets. It was nothing but an annoyance. What we're talking about here is essentially a small building made out of titanium with rocket engines attached to the bottom. Things like this don't wobble. If I didn't find out about autostrut I think it's safe to say I wouldn't even be playing this game by now.

Edited July 15, 2023 by pipe

[Alexoff]

I don't remember the wobble problem in KSP1 causing me any inconvenience at all. A couple of struts holds the two parts tightly together, if something wobble, then I forgot to add a strut. My very first rocket for Mun in 0.90 was an absolute nightmare, there were about 10 stages, there were solid propellant boosters on the 5th stage, I flew in a straight line, because I did not understand anything about orbits, I descended from a height of 200 km for a very long time and with monstrous costs fuel. But even this monster did not oscillate like almost any my rocket in KSP2.

[softweir]

I agree that the current level of flexing is excessive!

However, some flexing is realistic - there is video out there (but I'm darned if I can find it a second time) of an internal view of the ISS bending like a train on curved tracks, back when a faulty software update to Zvezda caused excessive, laggy attitude corrections.

Which brings me to an associated issue:- getting the auto-stability feature well-tuned is a significant part of allowing our rockets to bend realistically. If the autopilot is laggy and heavy-handed then it will make make the flexibility look worse. If the rockets are over-rigidified to compensate for poor auto-stability, then we lose the fun!

Of course flexing was a problem back in the early days of KSP 1: I remember, back in the day, old KSP player that I am, when not only did rockets bend, but the joints would slide weirdly  back and forth - because Unity was using a PhysX implementation that could only join objects at their centres of mass! At least we don't have that in KSP 2!

[RocketRockington]

10 hours ago, Dakota said:

It's an issue that is severely affecting the playability of the game for many people and we recognize that. Nate recognizes that and has been a lead organizer in these discussions to resolve this issue. We're also working with external partners to get more of an understanding of our potential options to address this within the game's engine.

If that's the case, why's it listed as just in 'design discussion'?   Have the designers been so busy for the last 5 months - or frankly since 2019 when this was visibly a problem in the "gameplay" video - that they couldn't figure out that the discussion should have been over about it now?  What's the debate that's happening?

[Klapaucius]

On 7/16/2023 at 5:59 AM, Alexoff said:

I don't remember the wobble problem in KSP1 causing me any inconvenience at all. A couple of struts holds the two parts tightly together, if something wobble, then I forgot to add a strut. M

In KSP1, I just stopped with struts altogether on rockets and used rigid attachment for everything--which you could do with advanced tweakables.  But it was a nuisance becuase you had to do it individually for every part.

One thing in KSP1 that was interesting (and that is not necessarily a good thing):  rigid attachment worked fine in rockets, but no flex whatsoever tended to cause aircraft to shatter on landing. 

[Lisias]

On 7/15/2023 at 2:59 PM, Alexoff said:

I don't remember the wobble problem in KSP1 causing me any inconvenience at all. A couple of struts holds the two parts tightly together, if something wobble, then I forgot to add a strut. 

And that's the difference between a "Modelling Dough" model from a "Lego" one. You need to respect the bricks limitations, otherwise where would be the challenge?

 

On 7/16/2023 at 12:12 AM, softweir said:

I agree that the current level of flexing is excessive!

On KSP2, for sure!

 

I find hard to believe that people really want to dumb down the game to the point in which a 7.5M wide, 220M tall rocket being able to even take off is… "realistic". That damned thing would not even manage to get on its feet on real life, what to say take off?????

Spoiler

More on : https://imgur.com/a/dngY6GJ

Nothing wrong on Juno by allowing this, but I prefer to play KSP¹ for a reason!

Where is the "STEM promoting" thing of the game?

Edited July 17, 2023 by Lisias
Hit "Save" too soon.

[cfds]

2 hours ago, Lisias said:

I find hard to believe that people really want to dumb down the game to the point in which a 7.5M wide, 220M tall rocket being able to even take off is… "realistic".

Where does KSP take aspect ratio into account? Flexing is just a function of number of joins, not the length of the parts.

[MechBFP]

8 hours ago, Lisias said:

I find hard to believe that people really want to dumb down the game to the point in which a 7.5M wide, 220M tall rocket being able to even take off is… "realistic". That damned thing would not even manage to get on its feet on real life, what to say take off?????

Exactly. 
What you showed is ridiculous, however this is also ridiculous.  So definitely needs to be some middle ground here. 

[PDCWolf]

On 7/16/2023 at 12:12 AM, softweir said:

However, some flexing is realistic - there is video out there (but I'm darned if I can find it a second time) of an internal view of the ISS bending like a train on curved tracks, back when a faulty software update to Zvezda caused excessive, laggy attitude corrections.

"2 or 3 mm over a hundred meters". That's, in terms of a game engine, negligible.

On 7/15/2023 at 1:48 PM, Dakota said:

Going to again reaffirm that we see wobbliness as a major issue and the team is actively working towards solutions - both addressing physics bugs that cause instability, as well as having design discussions building off of Nate's comments from the Calvinball Dev Update.

There's peace talks between warring nations and other conflicting groups that have taken less time, and we've been kept better updated about.

1 hour ago, MechBFP said:

Exactly. 
What you showed is ridiculous, however this is also ridiculous.  So definitely needs to be some middle ground here.

What you see there is the result of 3 mechanics:

1. Joint weakness, which allows joints to have elastic properties between them, to separate, bend and compress together.
2. A lack of part to part collision. To allow parts to do the "le funny" bend into each other thing without the parts in question exploding (this also had to be patched in at some point back on KSP1 as bigger parts were randomly exploding)
3. A disregard for structural simulation. As, if made of metal, that construct's individual parts should've collapsed into themselves and/or broken off into pieces way before any perceptible bending.

If anything, it's a very good example of why KSP's wobble is not a proper display of how to assess structural integrity, or build structurally sound stuff.

[Alexoff]

11 hours ago, Lisias said:

You need to respect the bricks limitations, otherwise where would be the challenge?

It seems to me that there are quite a lot of challenges in KSP2 without it. For them, it would be possible to add achievements in steam, but to make this is a challenge for developers, apparently...

[Lisias]

5 hours ago, MechBFP said:

Exactly. 
What you showed is ridiculous, however this is also ridiculous.  So definitely needs to be some middle ground here. 
 

I agree.

 

4 hours ago, PDCWolf said:

1. A disregard for structural simulation. As, if made of metal, that construct's individual parts should've collapsed into themselves and/or broken off into pieces way before any perceptible bending.

There're some on KSP¹, very minimalistic and even naive - but better than nothing. It's the auto-struts.

The auto-struts can also be seen as a tool for structural reinforcement. My problem with it is it being dirty cheap - using auto-struts should tax the user both on Funds and Weight on every part affected by it.

Using your ISS example (that bends 2 to 3 millimetres each 100 meters), you can bet your Slide Rule it costed NASA a lot of money in reinforcements, that by their turn taxed the whole structure with mass.

 

4 hours ago, PDCWolf said:

If anything, it's a very good example of why KSP's wobble is not a proper display of how to assess structural integrity, or build structurally sound stuff.

But still better than nothing!

 

11 hours ago, cfds said:

Where does KSP take aspect ratio into account? Flexing is just a function of number of joins, not the length of the parts.

Where I'm saying it does? I'm pinpointing how ridiculous would be a 220 meters, 7.5 meters wide rocket standing on the launchpad to be considered "realistic", as the people advocating for the plain removal of the wobble are telling.

But since we are here, let's put your claims on check:

Spoiler

The following picture is a contraption mande with two columns of Mk0 Fuel Tanks (filled).

The "Left" one is the ordinary stock one, the "Right" one is made with a hacked version of it where the Attachment Nodes' sizes were set to 2 (this setting is known to cause influence on drag, perhaps it would influence stiffness too?)

Well, nope. Both columns wobbled the same.

--------

So I hacked the Mk0 hacked part to include breakingForce and breakingTorque to 5000 to see if anything changes:

Nope. Same thing.

---------------------------

So I gave up and set AutoStrut to Root on everything:

And yep, we have an oscillation but it's because the joint between the first Mk0 and the base is overstressed.

So you have a point, but it's (frankly) irrelevant to this discussion because it didn't impeded me from doing something more or less similar from what we would do on real life: reinforcing the structures.

In a way or another, my argument stands: KSP¹ behave way more similar (or less dissimilar) to Real Life™ than Juno:New Origins, the model that some people is willing to see KSP2 taking.

My complain about the AutoStruts being dirty cheap, however, still holds - reinforcing the MK0 parts should had taxed me on Funds and Mass.

 

2 hours ago, Alexoff said:

It seems to me that there are quite a lot of challenges in KSP2 without it. For them, it would be possible to add achievements in steam, but to make this is a challenge for developers, apparently...

Perhaps, but so what would be the difference between KSP2 and Juno:New Origins? Real differences, not the sugar coating that rich game publishers use to make up simple, lousily designed  dumbed down games.

— — — — 

It essentially boils down to what kind of game we want: a KSP¹ sucessor, with the building challenges improved; or a glorified, sugar coated, gold plated (and way more expensive and buggier) Juno:New Origins clone. (that Lego versus Modelling Dough paradigm I had talked about).

On a side note, Juno:New Origins is already on the market, it's cheaper, it's fun enough and it runs perfectly fine on my current rig (not to mention being way better reviewed on Steam - they just released an update with propelled craft, by the way!!!). If KSP2 is going to be a Juno rip off, why bother buying it and still wait months and months until be able to play it?

Edited July 17, 2023 by Lisias
Damn. Think on a thing, wrote another. (sigh)

[Alexoff]

1 hour ago, Lisias said:

Real differences, not the sugar coating that rich game publishers use to make up simple, lousily designed  dumbed down games.

The real difference that Juno is working out seems to be 7 people. KSP2 is being developed by more than fifty people + developers from Squad. And another difference in positioning, since in KSP2 the game of the millennium was promised, and Juno was not positioned like that - no colonies, no multiplayer. The disadvantages of Juno are that you can make any procedural rocket with any procedural engine, which removes KSP challenge, where you need to make something unusual from the available parts.

1 hour ago, Lisias said:

I'm pinpointing how ridiculous would be a 220 meters, 7.5 meters wide rocket standing on the launchpad to be considered "realistic", as the people advocating for the plain removal of the wobble are telling.

It seems to me that in real life such a rocket will collapse under its own weight, and will not bend like a sausage. But in the KSP, it seems there is no such feature as the ultimate pressure on the part.