The Claw and Fuel Transfer

[SofusRud]

I am, like most of you, really excited about the upcoming updates. One of the more interesting parts coming up is the Claw, a part that allows us to "dock" with docking-port-free objects like asteroids, but also other craft. I fully recognize its function, necessity and general coolness.

However, one of the features of the claw does make me a bit concerned: the fuel transfer thing.

From a game standpoint it follows quite naturally: Fuel can be transferred from any two tanks in the same craft, when two craft dock they merge into one craft, and as the Claw allows us to "dock" this follows. This creates a few issues/raises some questions in my opinion. The way I see it, these issues/questions can be grouped into two categories: gameplay and realism. From the realism perspective you have the fact that having a grappling object that grapples onto another crafts' fuel tank, punctures it and sucks the fuel out seems unrealistic. The importance of realism varies from person to person, so the importance/validity of this complaint is subjective.

In my opinion the more important question has to do with gameplay balance. Does The Claw render docking ports obsolete? Is it overpowered? I personally subscribe to the idea that any part that is significantly superior to similar parts in a certain way should be countered by being significantly worse in another way. For example, The Claw could be excessively heavy (say 10 to 20 times heavier) compared to the regular docking ports, be exclusively radial attached, require large amounts of power, be fragile, have no docking magnetism, be highly asymmetrical, or a combination of some or all of these flaws.

This line of thinking got me to look at the way fuel transfer works in KSP at the moment. The fact is that if you have a craft with a fuel tank attached to an I-beam attached to another fuel tank, then the transfer between the tanks works perfectly fine, despite it having to go through a solid block of metal with no transfer capability. I would like to see this system altered. What I propose is a different type of fuel line. The regular fuel line is directional, indicating to an engine that it needs to take fuel from a tank not stacked on top of it. This new fuel line would be a "transfer fuel line, imagine it looking like the regular fuel line but a different colour and without the arrows on. In the previous example of TankA=>I-beam=>TankB, placing the "transfer" line on TankA and attaching it to TankB would allow fuel transfer between the two, but not act like a regular line otherwise. So if we had Engine=>TankA=>I-beam=>TankB with a transfer line between the tanks, then the engine wouldn't use fuel from TankB unless there was a yellow fuel line as well.

The way I see it, this would only have an effect with regards to using parts that can't let fuel flow pass, like I-beams, structural panels and the like, but could also mean that we could have a Claw that could attach and "merge" with a craft, but not siphon off its fuel, which I think would be a good alternative to what we are expecting.

What do you guys think?

[Kasuha]

I am also concerned what will the Claw do with fuel transfer, but in a different way. I don't mind that you can transfer fuel between any two tanks in a single ship regardless of what is in between them and I don't like the idea that you would need to add parts to keep the functionality we now have by default.

My concern is more about what changes will "docking" using the Claw cause on either of the two ships. Because it is known that even normal docking can cause (irreversible) changes that affect how fuel is used. But the example I linked is artificial, you don't usually build ships this way. With the claw, though, nobody prevents you to grapple any part of the other ship and the chance you'll starve the part of fuel is much more real.

[SofusRud]

I agree that it is an imperfect solution. It came primarily from realizing that in order to remove the fuel transferability properties of the claw, given that IMO it would otherwise be way OP from a gameplay standpoint, the whole way in which fuel transfer works would have to be overhauled/altered. It would however have the advantage of making the whole fuel transfer thing seem more "realistic", for those of you who care about that.

[Red Iron Crown]

I don't understand why the claw can transfer fuel, just about any scenario where I want to transfer fuel could be served by a docking port. There must be some use case that came up in testing, I guess. Maybe some asteroids will have harvestable fuel in them?

We'll have to see how it actually works when we get it.

[SofusRud]

I don't understand why the claw can transfer fuel, just about any scenario where I want to transfer fuel could be served by a docking port. There must be some use case that came up in testing, I guess. Maybe some asteroids will have harvestable fuel in them?

We'll have to see how it actually works when we get it.

Its because docking works by merging the crafts, so if you grapple onto another craft, then the two become one and you can siphon off the fuel. It seems to me that it wasn't the goal the devs had in mind but merely a coincidence stemming from a combination of the fuel transfer system and the way docking works.

So in a sense, when you latch your craft onto an asteroid, you really now have a craft with a large, heavy boulder part attached

[Alex_Leonardo]

In Kerbal attachment system mod (KAS) they have a "claw" but it just doesn't group the two things into one object.

I think you guys think that when they said "like a docking port" it had the literal capabilities of a docking port.

[Red Iron Crown]

Its because docking works by merging the crafts, so if you grapple onto another craft, then the two become one and you can siphon off the fuel. It seems to me that it wasn't the goal the devs had in mind but merely a coincidence stemming from a combination of the fuel transfer system and the way docking works.

So in a sense, when you latch your craft onto an asteroid, you really now have a craft with a large, heavy boulder part attached

I understand that, but it seems to me that the claw should have fuel transfer permanently disabled. I can't really speak to how difficult that would be to implement as I'm not familiar with the inner workings of KSP and I'm not a programmer.

I foresee fuel piracy becoming an issue in multiplayer.

[CaptRobau]

My two cents:

1. The claw was devised as a way for spacecraft to connect themselves to asteroids. At first glance fuel transfer makes no sense in that regard, if it's just about connecting craft to world. So I have the feeling the fuel transfer option was added to cover some other gameplay advantage that we can't think of or is introduced in the ARM update.

2. The way fuel transfer is handled is fine, so not a big fan of OPs fuel line idea.

[Kasuha]

If the Claw will make it possible to send rescue missions to refuel stranded ships with no docking ports then I'm all for it. There should be some kind of disadvantage in using the Claw so it doesn't replace docking ports but as last resort it's fine IMO.

[Red Iron Crown]

Heh, that's one of the reasons I put a docking port on every manned ship, even if I have no plans to dock with anything.

I would imagine that the claw will be significantly heavier than a docking port, but that's just a guess.

[Javster]

I'd think the lack of magnetism makes it suitable for asteroids but not stations.

[SofusRud]

The fuel-line idea itself isn't really that important to me to be honest. While it would make more sense, it also doesn't add anything useful to gameplay.

The whole point of that idea was a way to get around the big issue i have with the Claw. Once you have a part that can attach to another craft and transfer fuel you essentially have a docking port. in this case a docking port that doesn't need another docking port on the target craft in order to dock with it. Then where does that leave the regular docking ports? Where does leave the difficult but ultimately very rewarding process of learnig how to properly dock, with allignment and stuff? It will be relegated to a less important niche is my point.

If anyone else has a way to solve this perceived imbalance, then i very much welcome it.

[CaptRobau]

Well the advantage of docking ports is that they favor symmetry far more than the Claw as it has been described. The Claw is a docking node that attaches to everything. That means it's not going to be accurate. If you spear a craft without pinpoint accuracy, you'll probably have a craft that's not aligned with the thrust vector, meaning it'll drift off course. That's not an ideal situation.

[Sandworm]

(1) The fuel transfer in KSP is a total fiction. Moving liquid fuels between spacecraft is extremely difficult. I'm not sure it has happened, certainly not with cryogenic fuels. At a minimum it would require very specialized tanks (bladders) and equipment (pumps) demanding extensive pre-launch preparations.

(2) What does nasa think of "the claw"? I really doubt anyone at nasa would attempt to claw a spacecraft full of explosive fuels. There was talk of harpooning satellites, but only for purposes of deorbiting. Imho any object kerbal-built that has been 'clawed' should explode immediately upon de-clawing.

[coolitic]

Claw doing fuel transfer is a bit unrealistic (unless it's 2 claws attaching to each other), and the drawback of it is less stability and more break-ability.

[Kerbart]

I foresee fuel piracy becoming an issue in multiplayer.

You say tomato, I say tomato... I foresee multiplayer becoming a lot more... fascinating

As for using the claw as an alternative to docking... My take on that is that it should leave the "clawed" fuel tank with a capacity of zero, as it now has a gaping hole in it. But really, we're speculating on the functionality of a part we haven't even seen a screenshot from.

[architeuthis]

Claw doing fuel transfer is a bit unrealistic (unless it's 2 claws attaching to each other)

I don't think fuel transfer via claw requires any more elaborate handwaving than KSP's laughably unrealistic fuel transfer system does already. Even if a satellite (or some other spacecraft) wasn't originally designed to be serviced, it will still have a fill/drain valve somewhere on its propellant tank. We can just assume that the claw refueling tool is able to autonomously locate the valve, and bypass its seals, and has a universal adapter to interface with it. There is a RL precedent for this technology.

[Kasuha]

I foresee fuel piracy becoming an issue in multiplayer.

Not any more than using docking ports. If docking (in any form, including claw) of ships of two different players will be possible at all in multiplayer, I doubt it will be possible without consent of both players. Because both docking and "clawing" means two ships will become one, controlled by one player.

[6.forty]

You say tomato, I say tomato... I foresee multiplayer becoming a lot more... fascinating

As for using the claw as an alternative to docking... My take on that is that it should leave the "clawed" fuel tank with a capacity of zero, as it now has a gaping hole in it. But really, we're speculating on the functionality of a part we haven't even seen a screenshot from.

This is what I'd like to see, since it seems like a bit of a brute force tool.

[Dodgey]

Perhaps in order to undock the claw you have to physically detach it from the parent spacecraft. That seems very balanced to me.

[Red Iron Crown]

Not any more than using docking ports. If docking (in any form, including claw) of ships of two different players will be possible at all in multiplayer, I doubt it will be possible without consent of both players. Because both docking and "clawing" means two ships will become one, controlled by one player.

Assuming unilateral docking is possible (and I agree that is a big assumption), the claw would be much easier to hook a hostile ship with, given that it doesn't require precise alignment like a docking port.

I consider it highly unlikely that docking between two players will not be possible in multiplayer, I would think that docking is one of the more desirable interactions between players. How the game decides who controls what afterward remains to be seen.

[CaptainKipard]

I understand that, but it seems to me that the claw should have fuel transfer permanently disabled. I can't really speak to how difficult that would be to implement as I'm not familiar with the inner workings of KSP and I'm not a programmer.

Neither am I but I have a basic understanding of object-oriented programming concepts. There's something to be said for robust code. It seems to me that this whole Claw debacle smacks of either laziness or poor object design (in a programming sense). Seriously it just seems like they took the docking port code and added surface attachment behaviour. For gods sake, KAS has a much more reasonable grappler, and it's made by a fan! I ranted about this in the latest asteroid article comments so I wont go on.

Heh, that's one of the reasons I put a docking port on every manned ship, even if I have no plans to dock with anything.

Same here. I consider doing this just part of the game, afterall not all of my creations require a docking port, or a KAS fuel port.

(1) The fuel transfer in KSP is a total fiction. Moving liquid fuels between spacecraft is extremely difficult. I'm not sure it has happened, certainly not with cryogenic fuels. At a minimum it would require very specialized tanks (bladders) and equipment (pumps) demanding extensive pre-launch preparations.

Something like this is already being worked on.

I don't think fuel transfer via claw requires any more elaborate handwaving than KSP's laughably unrealistic fuel transfer system does already.

Just, wow.

Even if a satellite (or some other spacecraft) wasn't originally designed to be serviced, it will still have a fill/drain valve somewhere on its propellant tank.

Refuelling would require specialised multiple valves, not just a simple drain valve. It should be a separate part. This is off topic anyway.

We can just assume that the claw refueling tool is able to autonomously locate the valve, and bypass its seals, and has a universal adapter to interface with it. There is a RL precedent for this technology.

This is what makes me wut the most. Arguments like this which aim to dance around the core issue by making excuses like "Well just use your imagination". Erm, no. KSP is a product. It's a game specifically, i.e. something designed for escapism. Why in hell should any reasonable person have to put effort into maintaining the illusion? Creating an immersive experience is the job of Squad.

[Dodgey]

Ok. How can anyone give realistic criticism without using the claw for yourself. I just don't get it.

[Red Iron Crown]

Neither am I but I have a basic understanding of object-oriented programming concepts. There's something to be said for robust code. It seems to me that this whole Claw debacle smacks of either laziness or poor object design (in a programming sense). Seriously it just seems like they took the docking port code and added surface attachment behaviour. For gods sake, KAS has a much more reasonable grappler, and it's made by a fan! I ranted about this in the latest asteroid article comments so I wont go on.

I think it's a bit premature to call it a "debacle". I'm inclined to at least wait and see how it's actually implemented before criticizing it too harshly.

KSP is unusual in that it doesn't fit any of the "standard" game types very well. If Squad was making a first person shooter, for example, there are many existing examples of that sort of game with varying features, and players' expectations of how those games should work are pretty clearly defined. A sandbox spacecraft building game is different; there's no modern precedent to compare it to, and players' expectations of how things should work vary greatly.

KSP has evolved as it has developed, sometimes in directions that I suspect the developers hadn't imagined or planned for. And they've had to wrestle the Unity engine into performing in a style of game which I think the engine's designers hadn't anticipated (distances in gigameters!?). So I think we should cut them a bit of slack if their early release versions aren't as polished or perfect as we wish they were.

Now, that's not to say that they're above criticism, or that we should hold back negative feedback when part of the game doesn't work well or the way we think it should. That's part of the deal with early release software. But accusing the devs of laziness or bad programming practices without evidence is poor form, and is likely to get your suggestions ignored.

[CaptainKipard]

Ok. How can anyone give realistic criticism without using the claw for yourself. I just don't get it.

Because it's already been described in the Asteroid article. What don't you get?