How to do thrust curves in stock ksp?

[Kartoffelkuchen]

Hey guys, I knew there was a thread covering this already, but I'm unable to find it, so i ask here again. How do i do stock thrust curves?  Thanks for any help!

[martinezfg11]

 

[Kartoffelkuchen]

7 minutes ago, martinezfg11 said:

 

Yes, I know that thread, but there was a thread dedicated entirely to the new thrust curve feature in KSP 1.1, which I am looking for. Thanks for your help though!

[heliobyte]

Is this what you are looking for? 

 

[Kartoffelkuchen]

Thanks @heliobyte, that was what I was looking for. There unfortunately isn't an example yet - could somebody make a small tutorial? I am not sure if I understood this all correctly. :/

[heliobyte]

4 minutes ago, Kartoffelkuchen said:

Thanks @heliobyte, that was what I was looking for. There unfortunately isn't an example yet - could somebody make a small tutorial? I am not sure if I understood this all correctly. :/

If there is indeed an actual thrust curve feature  in 1.1.+ I think summoning @NathanKell would be your best bet for answers.

[nli2work]

thrustCurve keys ratio of fuel remaining to control flow rate, in turn controlling actual thrust. easiest example is SRBs

thrustCurve
        {
            key = 1 1           // full fuel, full flow rate.
            key = 0 0           // 0 fuel remaining, 0 flow rate
        }

fuel ratio should never be more than 1, as your tanks can't hold more than maximum amount. setting flow rate to values higher than 1 will produce initial spike in thrust (and heat production and the rest), which Jeb will leverage for unintended uses I'm sure.

There's a lot more to this I'm sure... the above is just from experimenting with an SRB in game. Using the simple curve above never burns all the fuel, the engine flames out when flow rate hits ~1% of max. NathanKell will hopefully explain in clearer terms.

Edited May 2, 2016 by nli2work

[NecroBones]

 

If I'm understanding correctly, then the normal behavior for an SRB without a thrust curve would behave the same as:

 

thrustCurve
        {
            key = 1 1           // full fuel, full flow rate.
            key = 0 1           // 0 fuel remaining, full flow rate
        }

.. Since it would be 100% flow rate from beginning to end. And then something like this would allow a tapering off of thrust in the last 10% of fuel:

 

thrustCurve
        {
            key = 1 1           // full fuel, full flow rate.
            key = 0.1 1         // 10% fuel remaining, still full flow rate
            key = 0 0.1         // 0 fuel remaining, 10% flow rate.
        }

 

Do I have this right? I'm thinking of using something like this in my packs, like SpaceY. A flat thrust curve, tapering off at the end is something reasonably easy for people to understand, and slightly more realistic than the hard cutoff we get now. I'd probably change the actual values though. Maybe last 5% of the fuel for the tapering range, or something.

 

 

[nli2work]

That's a good starting point. I'd run it through the curve editor to make sure there's no unintended spline overshoots. A big dip/spike in thrust is much more noticeable than a dip/spike in ISP. Multi-propellant engines with big variance in fuel ratio like air engines will take more tinkering. I still don't understand why there would be fuel remaining with a simple 1-0 curve.

A tweakable thrust curve in Editor would be really useful especially for SRBs where it burns just fast enough for TWR>1 for lower atmosphere, then faster burn rate for higher thrust in upper atmosphere.

[Kartoffelkuchen]

Thanks guys @nli2work and @NecroBones! That really cleared things up! I'll experiment a bit with it now.

[NecroBones]

22 hours ago, nli2work said:

I'd run it through the curve editor to make sure there's no unintended spline overshoots.

 

Curve editor? How do I not know about this? It sounds useful.

[swjr-swis]

On 5/1/2016 at 8:01 PM, heliobyte said:

Is this what you are looking for? 

 

No permission to see it. I've had this happen on several quoted threads lately.

Is there a problem with the forum software, or is NDA information being discussed in public sections?

[Stone Blue]

18 minutes ago, NecroBones said:

Curve editor? How do I not know about this? It sounds useful.

Another unbelievable, excellent sarbian creation:
 

 

[NecroBones]

Just now, Stone Blue said:

Another unbelievable, excellent sarbian creation:
 

 

 

Thanks! I'll check that out. Sarbian is my hero these days.

[heliobyte]

51 minutes ago, swjr-swis said:

No permission to see it. I've had this happen on several quoted threads lately.

Is there a problem with the forum software, or is NDA information being discussed in public sections?

It's fine, Kartoffelkuchen saw the link before it spazed out.

[Foxxonius Augustus]

whoopsie wrong thread

Edited May 5, 2016 by Foxxonius Augustus

[CobaltWolf]

psst @Foxxonius Augustus you posted in the wrong thread.