[1.3.0] Kerbal Engineer Redux 1.1.3.0 (2017-05-28)

[Galenmacil]

Just now, Padishar said:

That is entirely up to cybutek, but I certainly won't be implementing it.  Given the almost total un-usefulness of a terminal velocity readout, regardless of whether FAR is installed or not, I would actually vote for it to be completely removed instead.  I would, however, quite like to see some of the values that FAR allows other mods to have access to be displayed in KER, though even that would come quite low down on my list of things to do...

Uh? What do you mean by "totally un-usefulness". I strongly and respectfully disagree with you...

[Padishar]

Just now, Galenmacil said:

Uh? What do you mean by "totally un-usefulness". I strongly and respectfully disagree with you...

Then describe a use case...

[Galenmacil]

Basically, terminal velocity indicate the speed at which the current vessel drag will start to overcome its aerodynamic properties. If it were to free fall, that would be the speed it would reach. When ascending into orbit, you can calculate a ship "atmospheric efficiency ratio" by dividing the current speed by the terminal velocity. Going above 1 will result in increased fuel consumption for a proportionally reduced increase in speed. In other word, you want to stay as close to 1 as possible for optimal fuel efficiency...

So, considering this, this is of great importance.

Edited May 12, 2016 by Galenmacil
fixed typos

[Padishar]

1 hour ago, Galenmacil said:

Basically, terminal velocity indicate the speed at which the current vessel drag will start to overcome its aerodynamic properties. If it were to free fall, that would be the speed it would reach. When ascending into orbit, you can calculate a ship "atmospheric efficiency ratio" by dividing the current speed by the terminal velocity. Going above 1 will result in increased fuel consumption for a proportionally reduced increase in speed. In other word, you want to stay as close to 1 as possible for optimal fuel efficiency...

So, considering this, this is of great importance.

I've seen this argument made before on this forum but have yet to see any remotely rigorous proof that it's correct for a normal ascent profile.

The current vessel drag is determined by its aerodynamic properties.  Terminal velocity is the velocity at which the drag force is balanced by the weight force.

It requires so much thrust to keep any reasonably sane rocket anywhere near terminal velocity that you will be better off using a smaller engine, hence less dry mass, hence less fuel mass required.  The rocket will be much cheaper overall for exactly the same payload to orbit.  The fact it expends slightly more deltaV is irrelevant, it needs to burn less fuel to do so in a launcher that costs significantly less.

[Galenmacil]

We have different opinion on this matter. Arguing on it's validity is not my intention. "Terminal Velocity" is a factor "real rockets scientists" use in their works. Does it apply the same way in KSP? That leave to be proven. Perhaps if you could include it in future KER update, I would start testing whether or not respecting the terminal velocity in an ascension makes a difference or not.

Edited May 12, 2016 by Galenmacil

[Jacke]

3 hours ago, Galenmacil said:

We have different opinion on this matter. Arguing on it's validity is not my intention. "Terminal Velocity" is a factor "real rockets scientists" use in their works. Does it apply the same way in KSP? That leave to be proven. Perhaps if you could include it in future KER update, I would start testing whether or not respecting the terminal velocity in an ascension makes a difference or not.

Real rocket scientists only use terminal velocity when finding out what speed a falling object will approach.  For rocket performance and ascent profiles (initial vertical climb, programmed turn, gravity turn, coast, orbital insertion), they model the whole thing and find out what the performance is for small changes.  Real rocket engines usually don't have much throttle range so they can't use fancy throttle control like what is common in KSP.  There's only changing the propellant load and changing the timing of the orbital insertion.

Except for very high thrust rockets like some surface-to-air missiles, most real rockets don't accelerate fast enough to get to the point where reducing engine thrust will improve performance or avoid damage from overheating.  Again KSP can be different, but terminal velocity isn't useful here, drag accel and Q are.  I saw that in Mech Jeb's Ascent Guidance where using terminal velocity limits resulted in substandard performance.

The previous use of terminal velocity in KSP as an efficient ascent guide was based on an analysis that only works for a rocket that ascended vertically.  That sort of worked for some of the ascent in KSP before new aero, as rockets often had a large initial vertical climb.  With new aero or using FAR, even with Kerbin's 10% size compared to Earth, rockets are best flown with the programmed turn starting around 100m and 100m/s, perhaps just a bit higher.  They quickly get to close to flying horizontally, which completely breaks the usefulness of terminal velocity as a guide.

[Galenmacil]

I see your point Jacke. In previous version, when terminal velocity was displayed by KER I tended to avoid getting past it... But i never really compared if it did make a difference or not. So you both changed my opinion on the subject: I agree with Padishar now, if it is of no use then it should be removed.

[Fwiffo]

Hi folks, just wondering if anyone has a patched recent KER dll I can try to fix the bug with crossfeed from decouplers being ignored in deltaV calcs.  I've had this problem forever (since pre KSP 1.0.5) and saw some stuff about it on the thread about it today.  Presently using KSP 1.1.2 64-bit and KER 1.1.1.

Edited May 13, 2016 by Fwiffo

[Padishar]

3 hours ago, Fwiffo said:

Hi folks, just wondering if anyone has a patched recent KER dll I can try to fix the bug with crossfeed from decouplers being ignored in deltaV calcs.  I've had this problem forever (since pre KSP 1.0.5) and saw some stuff about it on the thread about it today.  Presently using KSP 1.1.2 64-bit and KER 1.1.1.

You will need to provide more details about exactly what isn't working.  Stack decouplers with enabled crossfeed should work correctly.  The best thing is to provide a craft file (that's preferably totally stock unless the problem is with specific mod parts), a screenshot of your KER window (in all stages mode in VAB), a description of what you think is wrong and, if possible, an output_log.txt/player.log file after you have done a "Verbose simulation log" (in the VAB settings or you can add a special readout in flight).

[Fwiffo]

Thanks @Padishar.  Turns out the scenario I was experiencing was caused by my own stupidity; I forgot to resequence the staging.

Thanks for patiently laying out the instructions on what you need for a bug report, and apologies for the red herring.

[Streetwind]

Hi all, I have a bit of an odd question...

I'm aware that KER in career mode works by requiring an Engineer Kerbal or a dedicated part onboard to see the readout in flight, until you have a level 3 tracking station. But, is there any way for me to switch this to require a Pilot Kerbal instead?

The reason I ask this is because pilots are severely underused. The one special ability they have gets rapidly rendered redundant by probe cores. Meanwhile, scientists are always useful, due to the MPL and the resetting of one-use experiments as well as some mods (like the KIS/KAS surface science pack). Engineers are also always useful - even more so than any other class, you could argue, with KIS/KAS being built on top of them, UKS and Extraplanetary Launchpads being built on top of them, and even stock KSP letting them give huge bonuses to resource mining.

I'm just looking for as many ways as I can find to make pilots a bit more useful in my next playthrough. And mind you, I'm not asking for KER to be rewritten to do this for everyone. If there was a way for me to do it myself, I would be happy already

[Padishar]

26 minutes ago, Streetwind said:

But, is there any way for me to switch this to require a Pilot Kerbal instead?

Not at the moment.  It is fairly trivial to change if you don't mind building it yourself.  Simply change the following line:

https://github.com/CYBUTEK/KerbalEngineer/blob/master/KerbalEngineer/Flight/FlightEngineerCore.cs#L123

It should also be fairly trivial to make it switchable by putting the class of kerbal in a string in the config.  Adding a control to the settings UI would be more involved but also not really necessary...

[Streetwind]

"...if I don't mind building it myself."

It's not so much that I mind, really, and more that I have no idea how I would do it. As a guess, it would probably require me to set up a development tool/compiler thingy? In that case, I'll probably pass, as I wouldn't know where to begin.

Still, thanks for the answer!

[Padishar]

14 minutes ago, Streetwind said:

"...if I don't mind building it myself."

It's not so much that I mind, really, and more that I have no idea how I would do it. As a guess, it would probably require me to set up a development tool/compiler thingy? In that case, I'll probably pass, as I wouldn't know where to begin.

Still, thanks for the answer!

Try this: https://www.dropbox.com/s/4qhbbdfizu4h8jn/KerbalEngineer_Streetwind.zip?dl=0

Just replace the DLL in your version with this one. The only change from 1.1.1.0 is that line now says Pilot (which I'm assuming is correct).

[Streetwind]

38 minutes ago, Padishar said:

Try this: https://www.dropbox.com/s/4qhbbdfizu4h8jn/KerbalEngineer_Streetwind.zip?dl=0

Just replace the DLL in your version with this one. The only change from 1.1.1.0 is that line now says Pilot (which I'm assuming is correct).

I just downloaded and tested this - it works perfectly! Many thanks!

[Padishar]

21 hours ago, Streetwind said:

I just downloaded and tested this - it works perfectly! Many thanks!

Since three members (including two rather high-profile ones ) have liked the post above, I will see about a PR to make this properly configurable.  Given it might be nice to use a different setting in different saves, it would make most sense for this setting to actually be stored in the save rather than the KER settings, so you don't have to remember to set it correctly for the save that you play.  I'm not actually sure if KER stores anything similar in the save so I'll have to investigate that and, if it proves to be difficult (or, more importantly, time-consuming), then I may just put it in the KER settings for now...

[SteveD80]

Not sure if the developer(s) care, but I managed to design a rocket that exceeds some limit.  With a standard ion engine pushing 9857 tons with 29063 delta v, it gives me 0 seconds of burn.  

I do not expect this issue to be addressed. I was just struggling to design a rocket with a lot of delta v and decided to see what it would look like with an ion.  I do not want to use a rocket with a twr of 0.01 and I doubt that anyone else would either.

Edited May 17, 2016 by SteveD80

[dewin]

13 minutes ago, SteveD80 said:

Not sure if the developer(s) care, but I managed to design a rocket that exceeds some limit.  With a standard ion engine pushing 9857 tons with 29063 delta v, it gives me 0 seconds of burn.  

I do not expect this issue to be addressed. I was just struggling to design a rocket with a lot of delta v and decided to see what it would look like with an ion.  I do not want to use a rocket with a twr of 0.01 and I doubt that anyone else would either.

KER bases dV calculations on the root part, so if your root part or staging are wrong you may get wrong results.

Also, did you have enough electrical power to run the ion engine?  It's possible that's factored in to burn times.

[SteveD80]

Just now, dewin said:

KER bases dV calculations on the root part, so if your root part or staging are wrong you may get wrong results.

Also, did you have enough electrical power to run the ion engine?  It's possible that's factored in to burn times.

Plenty of power and staging was fine.  I had a nuke in place first and it did not come close to the delta/v I needed so I swapped the fuel with xenon and stuck on an ion.  I'm pretty sure that it just choked on the amount of time it would take to burn 179200 units of xenon.  As I stated I don't think anyone would want to fly the rocket.  My hand calcs indicate that it would take 4.26 days (real time) to burn all the fuel.

[Padishar]

1 hour ago, SteveD80 said:

Plenty of power and staging was fine.  I had a nuke in place first and it did not come close to the delta/v I needed so I swapped the fuel with xenon and stuck on an ion.  I'm pretty sure that it just choked on the amount of time it would take to burn 179200 units of xenon.  As I stated I don't think anyone would want to fly the rocket.  My hand calcs indicate that it would take 4.26 days (real time) to burn all the fuel.

Did you save the craft file?  Because Xenon drains from all the tanks (in the same stage) at the same time and the ion engine only drains at a low rate anyway, I suspect that the rate that each tank was being drained at was below the minimum value that can be accurately simulated.  Is there any staging involved?  You will get better deltaV if you arrange your Xenon tanks in stages so you can drain just a few at a time and then drop their dry mass (which is considerable).  This will also mean fewer tanks are being drained simultaneously which will allow the simulation to work correctly.

[SteveD80]

I did not save, but I made the fuel tank with modular fuel tanks.  I just filled a  Rockomax X200-32 Fuel Tank with xenon.

And the rocket I ended up building was a waste of time to build.  I'm going to put in a request for a mod to alert me next time I build something so expensive.  But if you want that craft file you can have it.  It's got 12 k/s delta v at sea level + mach 1 but the bottom needs some work.  I wanted to send 6 Kerbals to low solar orbit for science and xp, but with the contracts I had it was far from worth the 3 Mil+ price.

Edited May 17, 2016 by SteveD80

[Padishar]

2 hours ago, SteveD80 said:

I did not save, but I made the fuel tank with modular fuel tanks.  I just filled a  Rockomax X200-32 Fuel Tank with xenon.

And the rocket I ended up building was a waste of time to build.  I'm going to put in a request for a mod to alert me next time I build something so expensive.  But if you want that craft file you can have it.  It's got 12 k/s delta v at sea level + mach 1 but the bottom needs some work.  I wanted to send 6 Kerbals to low solar orbit for science and xp, but with the contracts I had it was far from worth the 3 Mil+ price.

3 hours ago, SteveD80 said:

With a standard ion engine pushing 9857 tons with 29063 delta v, it gives me 0 seconds of burn.

What were you pushing that was 9857 tons?  Or is that the total launch mass?  Can you do a screenshot of the KER window in the VAB with the "Show all stages" button pressed?  Also, click the Settings button in the KER window and click the "Verbose simulation log" button and then upload your output_log.txt file...

 

[ExtremeSquared]

It may have been fixed by now, but a couple versions ago, the core game couldn't handle a TWR below a certain level, most likely due to FP inaccuracies. Acceleration would round to 0 when pushing asteroids with a single ion, and the xenon would drain away for 0 delta V.

[FélixBachiller]

Hello! I have some suggestions to add two important values to the mod that are missing. They are critical for manual orbit calculations, and I have a lot of problems because I can't find out them.

These values are the flight path angle or the angle between the horizon and the velocity vector and the geocentric inertial coordinates, those are like normal geographic coordinates but they don't rotate with the planet, but stay aligned to the stars. The X axis is the vernal equinox vector and the Z axis is the spin axis of Earth. Maybe the last one is impossible because KSP has a different reference system.

[dewin]

6 minutes ago, FélixBachiller said:

Hello! I have some suggestions to add two important values to the mod that are missing. They are critical for manual orbit calculations, and I have a lot of problems because I can't find out them.

These values are the flight path angle or the angle between the horizon and the velocity vector and the geocentric inertial coordinates, those are like normal geographic coordinates but they don't rotate with the planet, but stay aligned to the stars. The X axis is the vernal equinox vector and the Z axis is the spin axis of Earth. Maybe the last one is impossible because KSP has a different reference system.

Heh!  Coincidentally, I've been working on a bunch of orbital math myself using kOS -- there's a long series of steps on how to convert from position and velocity to the 6 Keplerian elements -- and some of my earlier work essentially finds the flight path angle indirectly (when realizing that the radial vector is not just a line from the planet out passing through your ship, but is instead perpendicular to prograde).

KSP uses a left-handed coordinate system though, so your +z is -y and I'm not sure which part of the xz equatorial plane is the vernal equinox vector. (Though +x is probably correct).