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is use AtmCurve broken??


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so im making an engine that has high isp at sea level and tapers off to a lower vacuum isp for space travel.. im trying to avoid this engine being a hybrid engine like the rapier. also this engine only uses liquidfuel as propellant and its not a jet engine.

so here is my problem, i want this engine to have around 1000 kn of thrust at vacuum.. no problem right? so i key in the max thrust at 1000, the isp, 3000 for 1 and 1000 for 0.. this puts me at 1000 kn at isp of 1000 for vacuum with a decent fuel usage.. but it puts me at 3000 kn for 3000 isp at sea level.. i guess this is how the game works for isp.. 

so to fix this i need to lower the thrust % at sea level.. the only way i know to do this is the atmcurve.. 

so i put like this..

        useAtmCurve = True
        atmCurve
        {
            key = 0 1
            key = 1 0.3
        }

this SHOULD put me at 100% thrust at 0 vacuum, and 33% thrust at 1 sea level.. but its not working.. 

 

any ideas?

 

ive tried the atmchangeflow to both true and false.. setting it to true makes the engine do like 5000 kn of thrust around 10,000m

 

 

edit, not sure what i did but after reloading the game like 20 times and changing numbers around it seems to be working.. ? ? 

Edited by aaronsta1
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As a noobish modder, Id suggest you to go to squad file in gamedata, use the .cfg for engines, copy and paste the relevant stuff for engine ISP into your part .cfg. Remember to change the details.

If I remember correctly, more like 

useAtmCurve = True
        atmCurve
        {
            key = 0 1000
            key = 1 3000
        }

i hope I did the right stuff here...

Max thrust should not increase?

 

Edited by Xd the great
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@aaronsta1, atmosphereCurve is the Isp (seconds) vs. pressure (atmospheres).  So if you want the Isp to be 1000 at sea level and 3000 in a vacuum, you need something like this:

atmosphereCurve
{
	key = 0 3000
	key = 1 1000
	key = 1.5 0.001
}

That will make the Isp 1000s at 1 atm pressure, and 3000s at 0 atm pressure.

maxThrust is the thrust in a vacuum (kN).  So if you set maxThrust = 1000, then with the curve above, you should get 1000 kN thrust in a vacuum and 333 kN at sea level.

 

Edited by OhioBob
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1 minute ago, OhioBob said:

@aaronsta1, atmosphereCurve is the Isp (seconds) vs. pressure (atmospheres).  So if you want the Isp to be 1000 at sea level and 3000 in a vacuum, you need something like this:


atmosphereCurve
{
	key = 0 3000
	key = 1 1000
	key = 1.5 0.001
}

That will make the Isp 1000s at 1 atm pressure, and 3000s at 0 atm pressure.

maxThrust is the thrust in a vacuum (kN).  So if you set maxThrust = 1000, then with the curve above, you should get 1000 kN thrust in a vacuum and 333 kN at sea level.

 

yeah but i want it backwards, i want the isp to be 3000 at sea level.. putting it that way the 1000 kn at vacuum turns to 3000 at sea level.. but i think i got it working with the atmcurve.. i dunno why but it didnt work at first but its working now.

the too tip still says the engine has 3000 kn of thrust, but its limited to 930 with the 0.3 on the atmcurve

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1 minute ago, aaronsta1 said:

yeah but i want it backwards, i want the isp to be 3000 at sea level.. putting it that way the 1000 kn at vacuum turns to 3000 at sea level..

OK, well then just flip the numbers in atmosphereCurve.  And if you want the thrust at sea level to be 1000 kN, the set maxThrust = 333.333.

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15 minutes ago, OhioBob said:

OK, well then just flip the numbers in atmosphereCurve.  And if you want the thrust at sea level to be 1000 kN, the set maxThrust = 333.333.

well yeah but then when im in vacuum it will only be 333.333 :/ 

is there a switch that makes the game ignore isp vs thrust? ive tried to set ignoreforisp true but that didnt work.. i think it doesnt work for liquidfuel.

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43 minutes ago, aaronsta1 said:

well yeah but then when im in vacuum it will only be 333.333 :/ 

is there a switch that makes the game ignore isp vs thrust? ive tried to set ignoreforisp true but that didnt work.. i think it doesnt work for liquidfuel.

Huh. I am going crazy for a new module.

Or using dry/wet mode like the panther afterburning engine. Manually toggle it. Or somehow make it auto switch when in atmo.

I am calling in the experts. @linuxgurugamer @SpannerMonkey(smce)

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5 hours ago, Xd the great said:

Huh. I am going crazy for a new module.

Or using dry/wet mode like the panther afterburning engine. Manually toggle it. Or somehow make it auto switch when in atmo.

I am calling in the experts. @linuxgurugamer @SpannerMonkey(smce)

Not in this.  @OhioBob is one (he replied above), and there are others as well

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7 hours ago, aaronsta1 said:

well yeah but then when im in vacuum it will only be 333.333 :/ 

is there a switch that makes the game ignore isp vs thrust? ive tried to set ignoreforisp true but that didnt work.. i think it doesnt work for liquidfuel.

I guess I don't understand what you want.  You want the Isp to be 3000s at sea level and 1000s in a vacuum, correct?  What do you want the thrust to be?  Do you want it 1000 kN at both sea level and vacuum?  If so, that doesn't make any sense.  Thrust is equal to the Isp times the mass flow rate.  So as long as the fuel flows at a constant rate, the thrust is going to be proportional to the Isp.  The only way to keep the thrust constant while the Isp changes is the alter to fuel flow rate.  You have a throttle for that.

It sounds to me like the game is doing what it is suppose to do.
 

Edited by OhioBob
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