Should KSP have a Delta-V readout?

[Sereneti]

there is no downside on a dv readout...

 

[ValleyTwo]

To be honest I am kind of surprised this question needs to be asked.

 

[Wjolcz]

11 hours ago, blorgon said:

For what it's worth, I think players should know how to do the calculation manually.

I'm fully in the 'yes' column, but maybe the happy medium here is a tutorial-style way to introduce new players to the concept of Delta-V—show them how to manually calculate it, how important it is. Once the tutorial has been completed, poof, you've got your Delta-V readout.

Yes, I agree. Simply having the dV equation in the KSPedia would work well too.

[Frybert]

I voted for no, not because I don't like the idea, but because I think its time for the devs to stop adding new features and simply work on fixing bugs. On the other hand, if they insist on adding new features this should be at the top of their list.

[awfulhumanbeing]

If estimated, yes. Because in real life you'd have to guess more or less.

[blorgon]

12 minutes ago, awfulhumanbeing said:

If estimated, yes. Because in real life you'd have to guess more or less.

What? Where'd you get that idea? You think they guessed at how much fuel they'd need to put humans on the moon and get them back?

Didn't mean to be so rude, sorry. It's actually a surprisingly simple equation. It gets a little more complicated when transitioning between atmosphere and vacuum, but not much more so.

Edited May 21, 2016 by blorgon

[Plusck]

I voted no, because

(a) you dont need it to start with at all, career mode is designed to introduce you to parts gently and get a feel for what gets you where, and it's perfectly possible to go everywhere in the system without knowing your exact dv

(b) delta-v calculations are guaranteed to be wrong for any complicated craft. If you have SRBs and LF engines firing together, the calculation is wrong as soon as you touch the throttle. If you use dual-mode jets they are simply impossible to get right. If you have a jet engine and an LV-N on the same craft, there is simply no way to know what its dv might be. If you go through the atmosphere, the dv calculation will be wrong. If you use drop tanks, the dv calculation will be complicated and possibly wrong. If you have to lock tanks for mass-balancing or other reasons, the dv calculation will be wrong. If you separate your craft into two independent parts, the dv calculation will be wrong.

So sure, get a mod, install the mod, understand that it's a mod therefore not "official" and therefore that you can't complain if it gets the dv calculations wrong.

[awfulhumanbeing]

11 minutes ago, blorgon said:

What? Where'd you get that idea? You think they guessed at how much fuel they'd need to put humans on the moon and get them back?

Didn't mean to be so rude, sorry. It's actually a surprisingly simple equation. It gets a little more complicated when transitioning between atmosphere and vacuum, but not much more so.

I mean, ksp is far less realistic anyway, and an average KSP player isn't a rocket scientist and they would have to guess really. So yeah, I wasn't really right, rocket scientists figure out dV without any problems, I'm sure, but if a KSP player was about to design a moon rocket, they would need a scientist to get all the stats.

[Gaarst]

12 minutes ago, Plusck said:

I voted no, because

(a) you dont need it to start with at all, career mode is designed to introduce you to parts gently and get a feel for what gets you where, and it's perfectly possible to go everywhere in the system without knowing your exact dv

(b) delta-v calculations are guaranteed to be wrong for any complicated craft. If you have SRBs and LF engines firing together, the calculation is wrong as soon as you touch the throttle. If you use dual-mode jets they are simply impossible to get right. If you have a jet engine and an LV-N on the same craft, there is simply no way to know what its dv might be. If you go through the atmosphere, the dv calculation will be wrong. If you use drop tanks, the dv calculation will be complicated and possibly wrong. If you have to lock tanks for mass-balancing or other reasons, the dv calculation will be wrong. If you separate your craft into two independent parts, the dv calculation will be wrong.

So sure, get a mod, install the mod, understand that it's a mod therefore not "official" and therefore that you can't complain if it gets the dv calculations wrong.

So you're saying Squad shouldn't add an essential feature to the game because it might not work ? Do you really want to start talking about all the things that were added in 1.1 which don't work ?

Also, you're not getting anywhere past Minmus without a dV readout or experience. You need either one of them, but to acquire experience without launching dozens of bound-to-fail missions, you need a dV readout, so...

And you should try KER (or MJ), while it might not be precise to the tenth of m/s, its dV indications are pretty accurate.

Edited May 21, 2016 by Gaarst

[Plusck]

5 minutes ago, Gaarst said:

So you're saying Squad shouldn't add an essential feature to the game because it might not work ? Do you really want to start talking about all the things that were added in 1.1 which don't work ?

Also, you're not getting anywhere past Minmus without a dV readout or experience. You need either one of them, but to acquire experience without launching dozens of bound-to-fail missions, you need a dV readout, so...

No, I'm saying they shouldn't because it will always be wrong, to a greater or lesser degree.

I got landers down on Ike, Gilly and Duna before I felt the need to install KER. I had a couple of failures but they were more about getting transfer windows than about running out of fuel.

[r_rolo1]

6 minutes ago, Plusck said:

No, I'm saying they shouldn't because it will always be wrong, to a greater or lesser degree.

Well, by that logic, we should also take the burn time of the game, because that thing will spit nonsense numbers a lot of times, when it simply does not throw a N/A on you ...

I really, really, don't get the whole " if it can't be perfectly accurate, better don't have it" line of thought some people showed in this thread. RL doesn't work like that and TBH, games also don't work like that ... and in case of KSP it is even worse because the whole game is built on top of a not so accurate representation of orbital mechanics that will always get things wrong

[blorgon]

16 minutes ago, Plusck said:

No, I'm saying they shouldn't because it will always be wrong, to a greater or lesser degree.

What exactly do you mean, 'wrong'? KER does a fantastic job—I've double checked my results with my own manual calculations dozens of times. It doesn't show transition delta-V, but that's usually not much of a gain anyway (almost always < 400 m/s in my experience).

I really don't understand why this is such a contested issue. Do you really think most new players are going to have the patience to do it your way? Why would you fight tooth and nail for something you think people don't need? Why do people on this forum consistently insist theirs is the only way to play the game? This is about providing a tool. You don't have to use it. Other people don't have to use it. But for the new players that don't know how to install mods, or are scared they'll mess their save games up, this is an absolute no-brainer.

Delta-V isn't the ONLY consideration in mission design, by the way. I think the most satisfying trial-and-error aspect of the game is tweaking your design to meet certain mission specifications and personal goals, not wondering whether you'll have enough fuel to even get there. I'm all about pursuing ultra-efficiency, because I find elegance in those kinds of solutions. Everybody plays the game differently, though. There are mission-design oriented players, there are flight-sim oriented players, and much more. You are not the exemplary KSP player, because there isn't one.

Missions are time-consuming. I'd be willing to bet that on even a Mun landing, a new player would get discouraged enough after playing for 20 minutes and discovering they can't get back off the Mun. I've had my fair share of times I spent hours getting somewhere and messed up because I didn't have enough fuel. If I weren't an utter space-nut, I'd have dropped this game in a heartbeat back in 2013 when I first started playing. The learning curve for non-science/engineering-oriented peoples is VERY steep. A delta-V readout would make it LESS steep. Get over yourself.

Edited May 21, 2016 by blorgon

[Gaarst]

53 minutes ago, Plusck said:

No, I'm saying they shouldn't because it will always be wrong, to a greater or lesser degree.

I got landers down on Ike, Gilly and Duna before I felt the need to install KER. I had a couple of failures but they were more about getting transfer windows than about running out of fuel.

Why should it be wrong ? KER works.

[Knaapie]

14 minutes ago, Gaarst said:

Why should it be wrong ? KER works.

I think he's referring to his previous post about complicated builds where you have multiple engine types on action groups to turn on and off at specific maneuvers, which use the same fuel tanks. This mainly happens with ssto's and multiple landers that reconnect to the main craft. I've had problems with LV-N engines paired with ION engines when activated at the same time (some time ago though).

KER still does work though. You sometimes need to change stages in the VAB or SPH in order to see the effects. And then it depends on how empty a liquid fuel tank is in space, for how much dV you're actually getting from your ION engines in interplanetary transfers. This where you need to guesstimate, KER can't predict when your less efficient engine is being used and when your high efficient engine is activated.. 

[blorgon]

25 minutes ago, Knaapie said:

I think he's referring to his previous post about complicated builds where you have multiple engine types on action groups to turn on and off at specific maneuvers, which use the same fuel tanks. This mainly happens with ssto's and multiple landers that reconnect to the main craft. I've had problems with LV-N engines paired with ION engines when activated at the same time (some time ago though).

KER still does work though. You sometimes need to change stages in the VAB or SPH in order to see the effects. And then it depends on how empty a liquid fuel tank is in space, for how much dV you're actually getting from your ION engines in interplanetary transfers. This where you need to guesstimate, KER can't predict when your less efficient engine is being used and when your high efficient engine is activated.. 

I'd argue these are pretty rare use-cases though. The majority of players that would benefit most from a delta-V readout probably aren't building this kind of stuff until later, when they know what they're doing. Maybe not though.

Either way it's a crap argument. 

Edited May 21, 2016 by blorgon

[Plusck]

1 hour ago, blorgon said:

...Why would you fight tooth and nail for something you think people don't need? Why do people on this forum consistently insist theirs is the only way to play the game?

...

Get over yourself.

I'm not the one getting upset here.

Forgive me for having an opinion.

Sorry but I couldn't be bothered reading a word of what you wrote between the quotes.

31 minutes ago, Gaarst said:

Why should it be wrong ? KER works.

KER gets it wrong, for all of the reasons that I gave.

It's easy to check how wrong it can be - simply enable staging and disable crossfeed on a set of docking ports (tried just now, from 3900m/s for the final stage after a docking port, it decided its dv was 1000m/s). That means you have to add a decoupler during the build to get the right figures. I haven't yet found out whether it still gets droptanks completely wrong, but it did in 1.0.5 - you had to add an engine such as an Ant during the build to get the right figures. And the other reasons I gave are self-evident reasons why it cannot be correct.

So KER gives merely a ballpark figure until you're actually in your final, single-stage configuration. Some people obviously think that this is necessary, and some rabidly so, but it's also the configuration where you can work it out with a single equation, and where minimal experience will give you a rough idea of what is possible anyway.

[blorgon]

4 minutes ago, Plusck said:

Sorry but I couldn't be bothered reading a word of what you wrote between the quotes.

K.

[Gaarst]

49 minutes ago, Knaapie said:

I think he's referring to his previous post about complicated builds where you have multiple engine types on action groups to turn on and off at specific maneuvers, which use the same fuel tanks. This mainly happens with ssto's and multiple landers that reconnect to the main craft. I've had problems with LV-N engines paired with ION engines when activated at the same time (some time ago though).

KER still does work though. You sometimes need to change stages in the VAB or SPH in order to see the effects. And then it depends on how empty a liquid fuel tank is in space, for how much dV you're actually getting from your ION engines in interplanetary transfers. This where you need to guesstimate, KER can't predict when your less efficient engine is being used and when your high efficient engine is activated.. 

 

8 minutes ago, Plusck said:

KER gets it wrong, for all of the reasons that I gave.

It's easy to check how wrong it can be - simply enable staging and disable crossfeed on a set of docking ports (tried just now, from 3900m/s for the final stage after a docking port, it decided its dv was 1000m/s). That means you have to add a decoupler during the build to get the right figures. I haven't yet found out whether it still gets droptanks completely wrong, but it did in 1.0.5 - you had to add an engine such as an Ant during the build to get the right figures. And the other reasons I gave are self-evident reasons why it cannot be correct.

So KER gives merely a ballpark figure until you're actually in your final, single-stage configuration. Some people obviously think that this is necessary, and some rabidly so, but it's also the configuration where you can work it out with a single equation, and where minimal experience will give you a rough idea of what is possible anyway.

If you know how to use it (ie: change staging to get accurate dV numbers) it works. A dV readout (or KER in this case) is a tool: if you know how to use it, then use it; if you don't, then learn.
I'm playing a RSS save, with Real Fuels (ie: dozens of different fuel configurations possible) and I still make it to space (and to wherever my mission is headed).

OfC, if you expect to just build your 12 RAPIER + 5 Nukes + 523 Ions SSTO and have your dV given to you without doing anything, then neither a dV readout nor anything else can help you.

If you know how to workaround these "issues", KER is accurate, so can be any dV readout.

Edited May 21, 2016 by Gaarst

[Pthigrivi]

Easy guys. Its possible for something to miss some edge cases and still be useful, and its true that misleading information is worth thinking about. Both can be right.

[Plusck]

2 hours ago, r_rolo1 said:

Well, by that logic, we should also take the burn time of the game, because that thing will spit nonsense numbers a lot of times, when it simply does not throw a N/A on you ...

I really, really, don't get the whole " if it can't be perfectly accurate, better don't have it" line of thought some people showed in this thread. RL doesn't work like that and TBH, games also don't work like that ... and in case of KSP it is even worse because the whole game is built on top of a not so accurate representation of orbital mechanics that will always get things wrong

Burn time estimates are often wrong because the previous burn was at reduced thrust. However it's a self-correcting system that ends up being more-or-less right within seconds. A dv calculation that is "stock" and supposed to be correct, but which only ends up being correct when you drop the last stage two years (game-time) down the road is going to get people - especially the noobs that you're trying to help - quite upset.

And I'm not saying there aren't unforgivable bugs in KSP as it is (such as, specifically, constant recalculations of orbits compounding rounding errors) - but within the limitations of the SOI system the orbital mechanics themselves are perfectly correct.

All I'm saying is (a) you don't need it to start with and (b) it gets increasingly wrong as you adopt more sophisticated strategies, so therefore it doesn't ever comply with the basic premise of what stock is supposed to be about. It's mod territory and rightly so (imho).

[Red Iron Crown]

I should really write a tutorial on how to work around KER/MJ giving inaccurate numbers for complex mission profiles. It certainly can be worked around, by "simulating" the mission in the VAB through tweaking fuel tanks and connecting/disconnecting modules.

At any rate, the simple, serially-staged case is fairly easy to get correct, and that's the one that is most important to new players who will benefit most from having it calculated for them. Trial and erroring through missions that are mathematically excluded from succeeding before the spacebar is pressed is not the better alternative here.

[basic.syntax]

What I learn from failure, is to overbuild  

[steve_v]

5 minutes ago, Red Iron Crown said:

the simple, serially-staged case is fairly easy to get correct, and that's the one that is most important to new players who will benefit most from having it calculated for them

Pretty much what I was about to say.
 

By the time the player gets to designing monstrosities that will confuse a dv calcultor, they are likely to have aquired a pretty good understanding of why it gets it wrong... at which point it becomes a non-issue.

While a lot of KSP is about trial-and-error, doing dv calculations by-hand every time you change something is only adding gratuitous grind. Learning that you need to do this by having missions fail (possibly hours into said mission) is, IMO, artificial difficulty, and borderline wanton cruelty to newbs.

[insert_name]

This would make my life so much easier 

[Knaapie]

15 minutes ago, insert_name said:

This would make my life so much easier 

Download KER, use it NOW !