Stock Game not very fun without Delta-V & TWR readout

[GoSlash27]

1 hour ago, Bill Phil said:

True. Even so, it's worth adding in. The potential problems from having delta v be innacurate already exist to some extent in maneuver nodes.

I agree with you in principle, but in practice perhaps not (at least from their perspective). It's one thing to have a free mod spitting out incorrect answers, but an entirely different situation when it's software people are paying you for. Perhaps they prefer to let this sleeping dog lie because a mod is available?

Best,
-Slashy

[Cpt Kerbalkrunch]

Seven pages now. If we keep at it, think we have a shot at Thread of the Month? 

[basic.syntax]

It's a fascinating collection of opinions on where the gameplay and challenges in KSP should be. 

[Just Jim]

32 minutes ago, basic.syntax said:

It's a fascinating collection of opinions on where the gameplay and challenges in KSP should be. 

Yes, there is... and I think in the end this is what it comes down to.

If and when the devs consider adding in any mod, which this more or less is, it should be in a way that satisfies as many players as possible, because there are so many different opinions and styles of playing. 

Edited March 24, 2018 by Just Jim

[sh1pman]

I had huge, multi-segmented mobile mining and refueling bases on most stock planets, tankers, orbital depots and transport ships flying around the Kerbol system before I installed the first mod. The game is definitely playable without delta-v and TWR readouts, given enough time and dedication. Sure, the rockets were far from optimal, but, ironically, that’s the very reason why I had to build this whole network of mining and refueling infrastructure, while also developing rendezvous and pinpoint landing skills in the process. What I’m trying to say is that if I had all the numbers from the start, I’d probably just build a couple of perfect rockets that can easily fly where I send them, land and take off on the first try, and return home safely. And that would probably be the game finished for me. Trying to overcome constraints like those we have in stock can make you learn and adapt, coming up with things that you’d miss otherwise.

Now, for the record, I’m in the camp “add the readouts to stock, but make them toggleable”. It’ll suit everyone’s taste, I guess. 

[Gargamel]

9 hours ago, Cpt Kerbalkrunch said:

Seven pages now. If we keep at it, think we have a shot at Thread of the Month? 

The previous thread we had (last week?) deserves it more than this one.  I linked it on the first page of this one I believe.    Very little if any personal arguments, and the cavemen showed up in force to give us some good lessons on easy ways to play the game their way. 

But I think the consensus would be happy with that Dv readouts should be in stock, if only because the consoles can't use mods, and if it does exists, it needs to be a toggleable option. 

[GoSlash27]

Another complication that I was just reminded of:

KER is incorrect every time it attempts to calculate the DV of a launch stage, even when it's the simplest possible launch stage.
 Atmospheric t/w will be correct, but neither atmospheric *nor* vacuum DV will be right, since the launch stage doesn't spend it's time purely in either condition. If it's a SSTO rocket, it's mean atmospheric density will be much lower than if it's a short burn SRB just to get things moving. KER has no way of knowing and any answer it gives will be incorrect.

 This gives rise to another problem: What is the "correct" DV of a stage in varying atmospheric density? The KER vacuum value? The "true" value, which is uncalculable? The closest estimate based on it's starting and ending atmosphere?

Best,
-Slashy

 

 

[Cpt Kerbalkrunch]

28 minutes ago, GoSlash27 said:

Another complication that I was just reminded of:

KER is incorrect every time it attempts to calculate the DV of a launch stage, even when it's the simplest possible launch stage.
 Atmospheric t/w will be correct, but neither atmospheric *nor* vacuum DV will be right, since the launch stage doesn't spend it's time purely in either condition. If it's a SSTO rocket, it's mean atmospheric density will be much lower than if it's a short burn SRB just to get things moving. KER has no way of knowing and any answer it gives will be incorrect.

 This gives rise to another problem: What is the "correct" DV of a stage in varying atmospheric density? The KER vacuum value? The "true" value, which is uncalculable? The closest estimate based on it's starting and ending atmosphere?

Best,
-Slashy

 

 

I've seen suggestions before to only show vacuum Delta V. To have the running calculations disabled during atmospheric flight. It would then recalculate when you land or return to vacuum. This is obviously not the greatest solution, but it sounds like it would work. If landing on another world, calculations would stop when you hit the atmosphere, but you'll know what you had when you got there, and it would recalculate when you land, so you know what you have left. It could also keep a running total of Delta V used during atmospheric flight for the entire mission. Also recalculating every time it detects a staging. This could help you figure out what is being used in flight and how much savings you gain through creative staging.

None of this would help planes, so I don't know if it's feasible. And I've also only seen screenshots of KER and MJ, so I'm not sure if they already do this or not.

[GoSlash27]

1 hour ago, Cpt Kerbalkrunch said:

I've seen suggestions before to only show vacuum Delta V. To have the running calculations disabled during atmospheric flight.

Cpt. Kerbalkrunch,
 So then it wouldn't display in the VAB? Or would it continue to provide 2 alternative incorrect answers?

Best,
-Slashy

[AVaughan]

31 minutes ago, GoSlash27 said:

Atmospheric t/w will be correct, but neither atmospheric *nor* vacuum DV will be right, since the launch stage doesn't spend it's time purely in either condition. If it's a SSTO rocket, it's mean atmospheric density will be much lower than if it's a short burn SRB just to get things moving. KER has no way of knowing and any answer it gives will be incorrect.

 

You might have an R7 style booster, without fuel lines but with the decouplers setup with crossfeed enabled, and fuel priority set to drain the radial boosters first.  KER has no way of knowing when you will detach those radial boosters.  (You might be planning to use them until you are sure the core will have enough TWR without them, by which time the core might be half empty).  You might also have an LES.  Again KER has no way of knowing when you will ditch it as no longer necessary.  The best any deltaV system can do is make assumptions and display numbers based on that assumption.

[blakemw]

The difference between Vac and atmospheric DeltaV is *for the most part* inconsequential. In fact usually deltaV charts just give the vacuum deltaV requirements even for launch from places like Kerbin and Eve, and make certain sensible assumptions about what engines people are using, like these dV numbers would be wildly wrong if you tried to use vacuum engines (in fact 3400m/s is quite wrong for Swivel, due to the Swivels abysmal ASL performance), and are bit exaggerated if you're using ASL engines with a flat ISP curve, but they are good enough as a guide. What's more by the time you're over 10km on Kerbin it is basically a vacuum for ISP purposes.

OTOH atmospheric TWR is more important than Vac TWR because it's what determines if your rocket can get off the launchpad. It's not a huge deal having only the Vac TWR though because it's a super simple calculation to adjust for, you can just subtract 5% for good launch engines, up to 20% for bad launch (but still launch-capable) engines and be close enough for purposes of getting off the pad.

Edited March 24, 2018 by blakemw

[Cpt Kerbalkrunch]

19 minutes ago, GoSlash27 said:

Cpt. Kerbalkrunch,
 So then it wouldn't display in the VAB? Or would it continue to provide 2 alternative incorrect answers?

Best,
-Slashy

That's where the problem seems to lie. It has to be displayed in the VAB, or else what's the point? You would need a caveat that says this is a close approximation; but things get difficult there. If you want info displayed, you want it to be precise. This is why I'm not sure if we'll ever see it in stock. Can it ever be exact? Accounting for all situations?

[AVaughan]

2 minutes ago, Cpt Kerbalkrunch said:

Accounting for all situations?

It can't, for the reasons I mentioned a few posts ago.  

Another situation it can't properly calculate is an Apollo style mission, where it can't know when the lander will be detached, and hence when the service module will stop having to push that extra weight.

[GoSlash27]

1 hour ago, Cpt Kerbalkrunch said:

Can it ever be exact? Accounting for all situations?

No, it definitely can't. Both due to what I pointed out and what @AVaughan said. The calc will never know exactly what constitute a "stage" or where (or if) it will be used.

Still... it may be useful even if it's wrong, as @blakemw points out.

Best,
-Slashy

[blakemw]

Everyone should be familiar with real life examples where you get an approximation that won't be accurate. Say you're using Google Maps and want directions from A to B, Google Maps will give you an estimated travel time and distance - the distance is actually precisely correct, but the travel time is based on some assumptions. Or if you're driving a modern electric car it'll give you an estimated range, although the driver will know that the estimated range isn't actually how far they can drive because it depends on speed, whether you're going uphill or downhill and so on, but it's still a really useful guide.

DeltaV is actually a precise number because it's produced by an equation - I mean yeah, atmosphere messes with the first 500m/s or so, but not by a very large amount, you might lose like 50m/s to the lower atmospheric efficiency, it's really not much. But how far that deltaV will actually take you, well that depends on how you use it. Some will be lost to aero drag, gravity drag and so on, you can massively multiply it via gravity assists, or waste it doing radial burns. It's not complicated. There's an exact number produced by a formula, deltaV, and then there is how far it'll take you which depends on how you use it. Lots of parallels in real life, should be perfectly intuitive to most people.

Edited March 24, 2018 by blakemw

[Cpt Kerbalkrunch]

13 minutes ago, AVaughan said:

It can't, for the reasons I mentioned a few posts ago.  

Another situation it can't properly calculate is an Apollo style mission, where it can't know when the lander will be detached, and hence when the service module will stop having to push that extra weight.

 

12 minutes ago, GoSlash27 said:

No, it definitely can't. Both due to what I pointed out and what @AVaughan said. The calc will never know exactly what constitute a "stage" or where (or if) it will be used.

Still... it may be useful even if it's wrong, as @blakemw points out.

Best,
-Slashy

Agreed. Which is why I don't see it in stock anytime soon. I think most players would realize that this is a close approximation and can never be exact, but others will expect precision and be angry if it's incorrect.

[GoSlash27]

1 hour ago, blakemw said:

DeltaV is actually a precise number because it's produced by an equation - I mean yeah, atmosphere messes with the first 500m/s or so, but not by a very large amount, you might lose like 50m/s to the lower atmospheric efficiency, it's really not much.

Actually, this understates the problem.

 The penalty for operating a "vacuum" stage in atmosphere can be quite severe, depending on how inefficient the engine is when clogged. See Poodle, Nerv, Dawn, Etc. Far more examples exist for Eve lifters, where only a few engines will work at all.

And DV isn't a precise number at all when it comes to atmospheric flight. Ditto for calculating the requirement to achieve orbit. It's easy when you have an airless body; simply calculate orbital velocity at sea level +/- surface rotation, then add the vis- viva to attain the desired orbit. Atmospheric numbers quickly devolve into guesstimates.

Best,
-Slashy

[AVaughan]

Well if the developers added a dV display, they could always label it "estimated vacuum dV".  That at least implies that there might be some approximations.  (And neatly sidesteps the in atmosphere approximations, where vacuum numbers for dV are normally "good enough".  As @blakemw mentioned, I find sea level TWR to be a much more important stat than sea level dV).   For maximum usefulness a stock dV display needs to be a per stage listing (like KER and mechJeb), rather than a just single number for the entire rocket.

[Cpt Kerbalkrunch]

8 minutes ago, blakemw said:

Everyone should be familiar with real life examples where you get an approximation that won't be accurate. Say you're using Google Maps and want directions from A to B, Google Maps will give you an estimated travel time and distance - the distance is actually precisely correct, but the travel time is based on some assumptions. Or if you're driving a modern electric car it'll give you an estimated range, although the driver will know that the estimated range isn't actually how far they can drive because it depends on speed, whether you're going uphill or downhill and so on, but it's still a really useful guide.

DeltaV is actually a precise number because it's produced by an equation - I mean yeah, atmosphere messes with the first 500m/s or so, but not by a very large amount, you might lose like 50m/s to the lower atmospheric efficiency, it's really not much. But how far that deltaV will actually take you, well that depends on how you use it. Some will be lost to aero drag, gravity drag and so on, you can massively multiply it via gravity assists, or waste it doing radial burns. It's not complicated. There's an exact number produced by a formula, deltaV, and then there is how far it'll take you which depends on how you use it. Lots of parallels in real life, should be perfectly intuitive to most people.

We're in agreement here, but I think it's not just atmospheric pressure that's the problem but drag as well. I put some pretty unwieldy beasts in the air. With the new fairings, I may start using them, but I always hated them and never bother. Part of this is because I despise autostrut and refuse to use it. As a result, I always have struts and strut connectors all over my ship; as well as blunt edges. This results in horrible drag, but I make sure to compensate for it (even on Eve ascent). Not sure if a  calculator can account for a hardheaded engineer. 

[GoSlash27]

1 hour ago, AVaughan said:

 For maximum usefulness a stock dV display needs to be a per stage listing (like KER and mechJeb), rather than a just single number for the entire rocket.

I agree, but again... "per stage" assumes that the calculator knows what a "stage" is. This cannot be assumed.

Best,
-Slashy

[klgraham1013]

16 hours ago, Cpt Kerbalkrunch said:

Seven pages now. If we keep at it, think we have a shot at Thread of the Month? 

Funny thing is, it's been talked about so much, and the truth is dV readouts will probably never be added anyway.

[Cpt Kerbalkrunch]

1 minute ago, klgraham1013 said:

Funny thing is, it's been talked about so much, and the truth is dV readouts will probably never be added anyway.

All good things come to those who wait...for KSP2. 

[Kobymaru]

2 hours ago, GoSlash27 said:

Snip

The answer is: vacuum dV. It's perfectly correct in space and on/around most of the bodies, it's almost perfectly correct in the upper atmosphere (for second stages) and it's still a reasonably good estimate for first stages because even those don't  spend much time in the lower atmosphere.

And please, stop succumbing to the perfect solution fallacy, where the absence of a perfect solution for every single player somehow prevents a big improvement for the majority of players.

 

Perfect is a bit better than imperfect, but imperfect is a lot better than nothing.

Edited March 24, 2018 by Kobymaru

[klgraham1013]

1 hour ago, Cpt Kerbalkrunch said:

All good things come to those who wait...for KSP2. 

Spot on, my friend.

[GoSlash27]

3 hours ago, Kobymaru said:

And please, stop succumbing to the perfect solution fallacy, where the absence of a perfect solution for every single player somehow prevents a big improvement for the majority of players.

Kobymaru,

 Perhaps you'd like to volunteer to explain that to all the people who complain when the software *they paid money for* doesn't work right?

 

Edited March 24, 2018 by GoSlash27