Should KSP have a Delta-V readout?

[John FX]

So you're asking 9 out of 10 people (near as damn it) to go through extra work, lose time playing KSP, and be generally shafted, so the tenth doesn't have to click a box in the options?

It seems that 85% of the people that care enough to vote in the poll on the forum want a Dv readout. The people that don`t haven`t really come up with any good counter arguments.

Without some form of Dv readout I would have stopped playing ages ago. I suspect this lack of information would limit the long term appeal of the game appeal for the majority of players.

"Oh, I exploded again? I`ll play fallout"

Whatever your feelings, Squad is a business and there is a bottom line. If they can keep more players interested and attract more new players with a Dv readout, well you don`t have to be Einstein to figure out what they are going to do...

Edited April 26, 2014 by John FX

[regex]

Yup, then you are able to keep the noobs down and have mysterious knowledge and maintain your position on the forum instead of the game getting wider appeal and people having the information they need to be able to build rockets properly.

It'd be really nice if we could have these discussions without insulting people or insinuating that they hate new players.

The people that don`t haven`t really come up with any good counter arguments other than the fact they already know how to build rockets and want to stay ahead of the noobs TYVM.

I still have trouble believing that writing a delta-V display that works with all player craft, including Apollo-style and all the other weird things people come up with, is a trivial task given the fact that MechJeb and Engineer still choke on certain things I build, even after Padishar's excellent work. It's not a question of having more information; the code to get masses and such is easy to get at.

Fact is, a feature like the delta-V indicators we have now don't hold up as a stock feature; it would need to be much better. Which means a lot of development time. This isn't a game like Orbiter where the craft is well-defined, this is a Lego set and that comes with its own complications.

Edited April 26, 2014 by regex
Grammar, maybe?

[Creature]

I'm with the yes crowd too. I can appreciate the "magic" statement to an extent, but it feels like it was given in the context of a game where we'd have only Kerbin, Mun and Minmus and no other planets. I don't see the magic in attempting a complex Laythe-mission (which I haven't done yet myself at all) dozens of times just to get the return stage's dV right, there's only frustration there. If it was just about getting a lander to Minmus and back, I might agree.

Also, I'm convinced that if you'd give the dV of the craft, it wouldn't drive away anyone. It's a simple concept in the end, it just tells you what's the maximum speed your rocket achieve before it runs out of fuel. Anyone who finds a single number to be too mathy and intimidating isn't going to play the game anyway for long. They're not gonna find the magic in figuring out the concept of dV from wikipedia, possibly learning logarithms (not everyone understands them) and calculating it with excel. They just quit. Heck, they wouldn't even know what to google for since they don't even get to orbit to see the two letters from a maneuver node.

Ranting aside, the "no crowd" has a valid point, but you can just add a difficulty options when you start a save. "Show vessel dV yes/no" "Show detailed orbital data yes/no" "IVA only yes/no (Warning, recommended for hardcore players only)"

[Hans Dorn]

I voted yes.

Squad should have an easier job at determining dV, since they can look at the actual fuel routing code instead of having to guess.

[John FX]

It'd be really nice if we could have these discussions without insulting people or insinuating that they hate new players.

Fair enough. The KSP community is generally very good but there are people who seem to be trying to keep the game only for the obsessive.

[Creature]

I still have trouble believing that writing a delta-V display that works with all player craft, including Apollo-style and all the other weird things people come up with, is a trivial task given the fact that MechJeb and Engineer still choke on certain things I build, even after Padishar's excellent work. It's not a question of having more information; the code to get masses and such is easy to get at.

Fact is, a feature like the delta-V indicators we have now don't hold up as a stock feature; it would need to be much better. Which means a lot of development time. This isn't a game like Orbiter where the craft is well-defined, this is a Lego set and that comes with its own complications.

That's a fair point and I agree that it would have to be good and not choke up easily. But if you present it in a simple manner, it should become intuitive that it's just one indicator and if you go very complex with docked parts and multiple engines and action groups, the indicator's reading isn't very accurate anymore. You could use the same argument against anything really and in a way you could say that maneuver nodes and apo/periapsis markers are already like this. They're good, but they do choke up when you have something as simple as a circular orbit, maneuver nodes can still be a pain sometimes and burn time indicator can give flat out false readings sometimes. I still wouldn't want to be without them.

[Red Iron Crown]

I still have trouble believing that writing a delta-V display that works with all player craft, including Apollo-style and all the other weird things people come up with, is a trivial task given the fact that MechJeb and Engineer still choke on certain things I build, even after Padishar's excellent work. It's not a question of having more information; the code to get masses and such is easy to get at.

Fact is, a feature like the delta-V indicators we have now don't hold up as a stock feature; it would need to be much better. Which means a lot of development time. This isn't a game like Orbiter where the craft is well-defined, this is a Lego set and that comes with its own complications.

That's an interesting point. I'd have thought that Squad would have an easier go of it than the modders, given that they have full "underhood" access to the game engine and the little gotchas like the newly massless parts, but I certainly could be wrong as I'm no programmer or rocket scientist.

I think you may be setting an impossible standard for new features, though. I'm not sure it's reasonable to expect a stock dV calculator to be completely perfect and bug-free in its first iteration. That said, KER and MJ work very well for the vast majority of designs. You really have to do something odd with staging or fuel flow to stump them, IME. I think most of the people looking for an in-game dV readout would be happy with one that functioned as well as either of those mods.

[regex]

Fair enough. The KSP community is generally very good but there are people who seem to be trying to keep the game only for the obsessive.

I applaud how you apologized while dropping yet another insult. Well done!

Yeah, no. As one of those who voted no, and is against this idea for several reasons already stated, I reject your statement that I want to keep this game only for the obsessive, or that I hate new players. Please refrain from further insults and blanket insinuations.

[FallsBrewer]

At a minimum I'd love to see deltaV and thrust to weight ratio. I've used Mechjeb and Engineer Redux to give redout information and they weren't available I doubt I would still be playing this game. In fact I didn't really get into it until I downloaded Engineer.

For me the fun of the game is in working things out and to do that you need data. However you can just as easily say the fun for you is in trial and error and that's where the problem lies. Different people enjoy the game in different ways and we're lucky that the devs support modding so much allowing us to do that.

The maneuver node system does show that there is a need for and enjoyment of, calculation in the game so I hope we do see some more numbers in stock. I'm not too worried about the quote either, the devs have changed their mind before and nothing is set in stone.

I completely agree with this. Without Engineer Redux and Alarm Clock I think I would have stopped playing shortly after getting to the Mun. Go ahead and put "Advance Instrumentation" a few levels deep on the tech tree and let players decide if they want it on their ship but it absolutely should be present in stock. Interplanetary missions require a big step up in design skill and orbital mechanics knowledge, I think the stock game needs to provide more helpful information to reduce people quitting in frustration or boredom after getting into orbit or landing on the Mun.

Tom

[regex]

That's an interesting point. I'd have thought that Squad would have an easier go of it than the modders, given that they have full "underhood" access to the game engine and the little gotchas like the newly massless parts, but I certainly could be wrong as I'm no programmer or rocket scientist.

The information needed for calculating delta-V is very easy to get at, including whether a part is massless, what resources it has, etc...

I think you may be setting an impossible standard for new features, though. I'm not sure it's reasonable to expect a stock dV calculator to be completely perfect and bug-free in its first iteration. That said, KER and MJ work very well for the vast majority of designs. You really have to do something odd with staging or fuel flow to stump them, IME. I think most of the people looking for an in-game dV readout would be happy with one that functioned as well as either of those mods.

I'm speaking from what I consider a "realistic" vision of how bugs in a video game are treated. How do you think it would look if the delta-V calculator in this game were like Engineer right now, great as it is? I think there would be a fair amount of adopters like yourself, and I, who would consider it "more than adequate", but at the end of the day it would be considered a sore spot by a lot of people ("If only the devs could write a proper delta-V calculator, amirite? They can't do anything else right..."). You know they type, and they are vocal. I just don't think it's going to be well received unless it's well-polished, and I also maintain that it's going to take several iterations to get it right, and that it will require a lot of new GUI elements to support "strangely-built" craft. Letting the player define delta-V sections to support those odd craft, as previously suggested, adds a whole new level of complication on use, even if done simply (I have an idea on how it could be done).

If anything, this should be a consideration after all the main features of the game are done and it requires some thought.

[sanoj688]

What I want to see before a Delta-V readout, is an Apoapsis readout! And periapsis while we're at it. It's super easy to code and pretty handy when trying to make orbit (don't need to switch to map view)

I didn't both reading 11 pages of comments but I really don't think there is a good reason NOT to want THE POSSIBILITY of a Delta-v readout.

The only downside is that it takes time to code, but that shouldn't be a reason not to want it! I don't need the stock delta-v readout (or ap/per) any time soon, but I do feel like this needs to be in the final game.

[Red Iron Crown]

I'm speaking from what I consider a "realistic" vision of how bugs in a video game are treated. How do you think it would look if the delta-V calculator in this game were like Engineer right now, great as it is? I think there would be a fair amount of adopters like yourself, and I, who would consider it "more than adequate", but at the end of the day it would be considered a sore spot by a lot of people ("If only the devs could write a proper delta-V calculator, amirite? They can't do anything else right..."). You know they type, and they are vocal. I just don't think it's going to be well received unless it's well-polished, and I also maintain that it's going to take several iterations to get it right, and that it will require a lot of new GUI elements to support "strangely-built" craft. Letting the player define delta-V sections to support those odd craft, as previously suggested, adds a whole new level of complication on use, even if done simply (I have an idea on how it could be done).

People are going to complain either way. Don't implement it, and you get threads like this one. Implement it, and people will complain about the implementation or bugs. Address those concerns in an update, and people will complain that they've ruined the old dV calculator with the new version. Fear of criticism cannot be the deciding factor here as they're going to be criticized one way or the other. I personally think KER is polished enough for integration into the core game, but maybe I'm just so used to it that I don't see its flaws as clearly anymore. What are the things in KER that you think would need fixing?

If anything, this should be a consideration after all the main features of the game are done and it requires some thought.

I respectfully disagree. A rocketry game that doesn't calculate delta-V is incomplete, in my book. It's like a shooter with no ammo counter, or an RTS with no resource counters.

[sanoj688]

A rocketry game that doesn't calculate delta-V is incomplete, in my book. It's like a shooter with no ammo counter, or an RTS with no resource counters.

Amen brother.

[regex]

I personally think KER is polished enough for integration into the core game, but maybe I'm just so used to it that I don't see its flaws as clearly anymore. What are the things in KER that you think would need fixing?

Have you ever built an Apollo-style craft or anything else highly modular? Certain combinations of parts can trip it up and certain staging configurations can do the same. There needs to be a simple way to handle that sort of thing through the GUI. Unfortunately that adds a lot of complications to use.

I respectfully disagree.

Yeah, we're going to disagree on this one. I think the mods we have right now do the job just fine and I also appreciate the learning and discovery inherent in not having that information.

[Red Iron Crown]

Have you ever built an Apollo-style craft or anything else highly modular? Certain combinations of parts can trip it up and certain staging configurations can do the same. There needs to be a simple way to handle that sort of thing through the GUI. Unfortunately that adds a lot of complications to use.

My usual interplanetary mission profile from LKO is:

Transfer stage + return stage + lander

Detach transfer stage

Detach lander, descend, ascend (may be some staging in here depending on destination)

Rendezvous and dock with return stage

Return

The only place the dV calculators I've used trip up on this is if I use the return stage to do the rendezvous with the lander (and even then, it's calculating correctly, I'm just not sure if I'll be able to make it home until I'm docked). I haven't run into trouble with particular parts combinations, though I generally use only stock parts. Maybe I've just been lucky in not stumbling onto one of the bad combinations?

There are definitely some unusual staging arrangements that confuse them, though. They're unusual enough that I would consider them edge cases.

[Alchemist]

I'm speaking from what I consider a "realistic" vision of how bugs in a video game are treated. How do you think it would look if the delta-V calculator in this game were like Engineer right now, great as it is? I think there would be a fair amount of adopters like yourself, and I, who would consider it "more than adequate", but at the end of the day it would be considered a sore spot by a lot of people ("If only the devs could write a proper delta-V calculator, amirite? They can't do anything else right..."). You know they type, and they are vocal. I just don't think it's going to be well received unless it's well-polished, and I also maintain that it's going to take several iterations to get it right, and that it will require a lot of new GUI elements to support "strangely-built" craft. Letting the player define delta-V sections to support those odd craft, as previously suggested, adds a whole new level of complication on use, even if done simply (I have an idea on how it could be done).

If anything, this should be a consideration after all the main features of the game are done and it requires some thought.

That's probably the main point why it's not implemented yet - no algorithm can calculate true Dv for really complex setup without taking in account mission profile, and having the display that follows some rules could be considered as "play by these rules, or you won't have the Dv display".

Of course, I can imagine how even a relatively simple Dv calculator could be used to properly calculate Dv of a mothership that detaches several landers at different points, but that's so much work in the VAB (detaching parts and changing fuel levels) that most of us would go "screw it, let's just ensure it's a sure overkill".

Yes, precise Delta V calculations is how real world space agencies work. But they also have big teams of engineers, a bunch of time for mission planning and extreme costs of bringing extra payload up there (especially, given that real launch vehicles aren't scalable, so going just out of capacity means big problems), so everything is maximally simulated at early stages of planning and recalculated at each iteration. In KSP there's almost no border between simulation and flight.

I think, Delta v display (even a simple one) wouldn't hurt anybody. As for ultra complex mission profiles... if you invented your unique grand tour scheme, it's up to you to invent how to use given tools to estimate it's capabilities. There have been oversimplifications in many features, but in the end there are not too many complains about that (and the people who want ultra realism or advanced options in such aspects just make and use mods) so the devs should be free to make it as they can and as they think fit.

[Tarmenius]

... I wouldn't have a problem with it being stock if ... [it] took no effort on the part of the programers (which it will not).

Indeed, it would be wonderful if code could implement itself.

Expect to see a lot of "I have 200,000 Delta-V is that enough to get to the Mun because I keep missing it when I burn straight towards it" Posts.

The only difference between that and the kinds of posts we see already is that in your example, the question is more informed. Is that really such a bad thing?

... it will require a lot of new GUI elements to support "strangely-built" craft.

You make an excellent point here. KSP does tend to inspire some wildly unconventional designs, and getting a delta-v indicator to work with them could prove more difficult than any of us can anticipate. If that turned out to be the case, then you may be right in suggesting that it wait until the game is more complete before being officially considered. Which would put the feature in the category of "things the developers haven't gotten to because of time constraints" and would rightly be left to the modding community.

As a side note, this discussion has been very interesting to follow, with excellent points made on both sides. I would be really curious to know whether it has at all changed the development team's view of the topic.

[sanoj688]

We would be doing the developers and everyone else a favor if we would make an inventory of all the strange cases that would cause problems with a delta-v system.

I think a common one is where you have a stage where the engines are pointing upwards and it gets counted as negative Delta-v. It would be beneficial to have all the problem cases written down. There can't be *that* much cases, and I'm sure the community as a whole can put their heads together to come up with solutions, instead of bickering about could go wrong.

[m4v]

edited: nevermind.

[Adslegend]

Would be nice to have so that you don't have to guess if you have enough fuel to complete the mission.

[Seret]

Fact is, a feature like the delta-V indicators we have now don't hold up as a stock feature; it would need to be much better.

I disagree. I think KER and Mechjeb generally do a good job. The fact that there are a few corner cases doesn't preclude something from being good enough to be stock. There are plenty of stock parts and features that behave oddly in a small number of situations. Having something that gave a figure in the right ballpark for TWR and ÃŽâ€v in the VAB/SPH would be a huge improvement. I could live without ÃŽâ€v readings once in flight and docking things together, but getting it right for the first few stages of a launch vehicle isn't hard.

[TMS]

We would be doing the developers and everyone else a favor if we would make an inventory of all the strange cases that would cause problems with a delta-v system.

But that's not nearly as much fun as moaning about things from the sidelines though.

Incidentally, Padishar has asked people to submit crafts that trip KER up to the development thread.

[Superfluous J]

You make an Apollo-style craft and as soon as you put a docking port on it, a little /!\ icon appears next to the dV reading. You click that or hover and it says:

"You've added docking ports to your craft. Note that docking, undocking, transferring fuel and supplies and otherwise modifying your craft in-flight could make these dV predictions inaccurate."

And then a checkbox for "Never alert me of this again" next to the OK button.

[Padishar]

Warning: wall of text approaching...

I personally think KER is polished enough for integration into the core game, but maybe I'm just so used to it that I don't see its flaws as clearly anymore. What are the things in KER that you think would need fixing?

I'm going to have to chime in here, I reckon. First off, thanks for the positive appraisal of KER, however, there are still a number of issues that would need to be "fixed" before I would say it is good enough to be integrated:

1. The simulation code doesn't cope correctly when a decoupler is the root part of the ship or is attached to its parent the "wrong" way round. This is a flaw in the code that simulates the decoupling action, basically the entire ship gets decoupled so the next stage(s) effectively doesn't exist and no calculations are done for it. It currently removes the decoupler and all children of it from the vessel, but if it is the root part then this removes the whole vessel. The decoupling code needs to be changed to only discard those parts that are "under" the decoupler. The same "issue" can be seen in the core game, with the staging of the decoupler causing a vessel switch (complete with messages about focus and timewarp) that doesn't normally happen when staging a decoupler.

2. The in-flight display needs a mode that ignores the staging of the vessel and simply shows the deltaV available with the engines that are currently active, e.g. it will burn the engines until they run out of fuel and then stop. This will enable people that activate and deactivate engines outside of the staging process to get a readout of deltaV for the current state of the vessel.

3. Something needs to be done to account for the velocityCurve of jet engines while in the SPH/VAB so the user can see the thrust/TWR at various airspeeds and a control to adjust the atmospheric pressure to intermediate settings would also be useful (you can currently switch between sea level and vacuum but you may want to know figures for your spaceplane in high altitude flight).

I plan to fix these in the simulation code (and make various other tweaks/optimisations) in the near future and Cybutek is working on a substantial UI rewrite that should result in an even more "polished" KER.

I respectfully disagree. A rocketry game that doesn't calculate delta-V is incomplete, in my book. It's like a shooter with no ammo counter, or an RTS with no resource counters.

I agree with this. The message from Squad is somewhat contradictory, with the "kerbal" comical way on one side and the "we're partnering with NASA" serious way on the other. The only reason I can see to vote no to this poll is if you feel really strongly that there are other things the devs should be working on first (and then you should actually vote "not yet"). Adding various KER style readouts to the stock game in an optional way and defaulting them to off would have no impact on players who don't want them but would make the (apparently large) majority of current users happy. I would suggest an in-game training scenario "Introduction to rocket science" so users that want to can have Wernher vonKerman introduce the basic concepts of TWR, ISP and deltaV and introduce the readout displays along with showing how various edits to the vessel affect the numbers. Running this tutorial would automatically enable the readouts and Wernher would explain that they can be turned off again in the options if desired.

As for saying it would take a large development effort to implement, if I were working on KER full time, the changes I have done so far would have taken less than two weeks and the changes I still plan to do would take about another week. If I were a dev working for Squad, most of the issues caused by the recent 0.23.5 update would simply not have happened, they would have been fixed almost instantly as soon as the underlying change was made (e.g. changes to struts making them transfer fuel in the simulation, the flow changes for monoprop and xenon etc). Other recent fixes to work with various mod engines would also not have been necessary as, with access to decent documentation or the core code, it would have been written "correctly" in the first place.

I only started playing KSP about 6 months ago. I had heard about it a couple of years back but never got around to trying it. I checked out the demo and initially I enjoyed it a lot but I very quickly came to the conclusion that it wasn't practical (read fun) to design a rocket for a purpose without, at least, readouts of TWR and deltaV. It just involved too much trial and error and restarting your missions several times because you haven't added enough fuel to get home gets discouraging very quickly. I had basically decided to not buy the full version but, luckily, I happened to watch a video where someone was using KER and the availability of that mod was what changed my mind...

(Wall? More like a cliff )

Edited April 26, 2014 by Padishar

[Red Iron Crown]

Warning: wall of text approaching...

*snip*

Padishar, that post really gives us common players some insight into what goes into an informational tool like KER, thanks for taking the time to write it.