Incorrect burn time

[Dhafeuwst]

Hello,

I have a problem with burn time calculation. I have searched around the forum before posting this, but didn't find any workaround.

KSP Version: 1.0.4.861 (WindowsPlayer) Steam on Windows 7 64bits

What Happens: Burn time is always incorrect even without staging

Mods / Add-Ons: None, then KerbalEngineer - 1.0.18.0 (same problem before and after installing the mod)

Steps to Replicate:

Create any manoeuver node

Result:

Estimated burn time is always mere seconds or not estimated at all, even after some burn applied after the last stage release, and even for burns of several minutes.

Other Notes/Pictures/Log Files:

I have seen somewhere else that you need to burn a little moment before the estimated time is calculated correctly after a stage release. This does not change the figures.

Thanks !

[Gaarst]

It's not a proper bug, but a known and annoying issue. It is the game's way to calculated manoeuvres that is the problem, it has nothing to do with your install and it will happen on every install you make.

As a solution, I'd suggest using exclusively KER for your burn times (IIRC, the manoeuvre readouts are in the "orbital" category, but not in the preset, you'll have to add them yourself for them to display: go to Edit on the KER bar, and add whatever readout you want). You'll still have to set the manoeuvre in map view though.

[Superfluous J]

Hm. My burn time is always wrong until I do a bit of burning (like in your Notes) and then it's as accurate as can be expected. I've never seen it not go up once you start burning.

I don't even know if log files would help in this case, as I doubt "how much you're thrusting" and "how long the node says it will take" are logged under any circumstances.

[Dhafeuwst]

@ Gaarst : thanks for the workaround. That will help me a lot, since I'm new and can't estimate the burn time properly out of experience yet.

@ 5thHorseman : how long do you have to burn before the burn time goes up ? I guess if my stagings have very different thrusts, that time might be quite long, depending on the "adjudtment" mechanics of the game. I will pay attention to this next time.

[Claw]

First off, welcome to the forums!

Secondly, thanks for using the bug report template. (Another )

I have seen somewhere else that you need to burn a little moment before the estimated time is calculated correctly after a stage release. This does not change the figures.

Thanks !

This is indeed the case. The burn time estimate only calculates after the engines have run for a second or two (it doesn't take long), and it will calculate based off your current acceleration. So if you only turn the throttle up a little, the estimated time will be a high estimate compared to running at full throttle. KSP's built in burn time estimate is really (really) basic. It won't remember previous calculates after certain events (such as saving and reloading), and it won't take into account things such as staging to a new engine stack, or dropping fuel tanks along the way. (I think most of that might have been said already...)

Personally I use MechJeb for burn time estimates, but KER works just as well for that too (personal preference for how information is presented). I think these are the two primary add-ons that provide that sort of information.

Cheers!

~Claw

[Alshain]

They need to fix this already. The game should be able to do this more accurately I would think.

I've noticed it has gotten increasingly inaccurate too. It used to be it would get pretty close after a burn. Now I find even after a burn it can be 1 second for every 5 seconds of burn off, and that is assuming you split the node (the proper way).

Edited September 26, 2015 by Alshain

[Superfluous J]

@ 5thHorseman : how long do you have to burn before the burn time goes up ? I guess if my stagings have very different thrusts, that time might be quite long, depending on the "adjudtment" mechanics of the game. I will pay attention to this next time.

To be honest, I'd have to test (I use KER and its readouts are far more useful, so I usually don't even look at the navball readout anymore) but it seems that if I hit shift, then X immediately (far less than 1 second later) the timer is pretty accurate. I recall in the past having to hit Z then X (again, immediately) to get a good readout, but that can be dangerous with large, spindly ships.

One thing KSP doesn't do is guess ahead based on fuel consumption or staging. It goes based of how much thrust you have, possibly also with some calculation based on percentages (If you thrust at 33%, it multiplies it by 3. This would explain why I can just hit shift and then X and get a good readout) but I'd like to test that before saying anything for sure. What I mean by it not guessing is, is if you've got 20m/s² of thrust and need to go 2000m/s, it will say you need to thrust for 100 seconds, regardless of the fact that your TWR (and therefore thrust) will increase as you burn fuel.

[Dhafeuwst]

Now I find even after a burn it can be 1 second for every 5 seconds of burn off, and that is assuming you split the node (the proper way).

Yep, that's quite the behavior I seem to have too. Since I now use KER's figures, I can focus more on what is wrong and less on mistiming catastrophies, and it seems to become accurate after some time.

I landed my first rover on Minmus tonight thanks to this. It can't steer with its wheels because I failed somewhere assembling the rover to the launcher, but it can bounce thanks to the reaction wheel in a rather controllable manner.

[Crashgroan]

I figured it out.  The same thing happened to me when I was flying my SSTO and all of the engines were in the same stage and I would just activate and inactive them whenever.   You have to separate the engines to a different stage. 

For example, I had all of my RAPIER engines in one stage and the Necular engine in the same and it was showing the burning time if I used both of the engines.  All you have to do is to move the engines to different stages so when I did was move the nuclear engines to the first stage and the RAPIER engines to the last.

[Chel]

3 hours ago, Crashgroan said:

I figured it out.  The same thing happened to me when I was flying my SSTO and all of the engines were in the same stage and I would just activate and inactive them whenever.   You have to separate the engines to a different stage. 

For example, I had all of my RAPIER engines in one stage and the Necular engine in the same and it was showing the burning time if I used both of the engines.  All you have to do is to move the engines to different stages so when I did was move the nuclear engines to the first stage and the RAPIER engines to the last.

Welcome to the forums, @Crashgroan, unfortunately this thread has been dead for 3 years, so you might want to start a new topic instead