[1.0.5] Advanced Jet Engine v2.6.1 - Feb 1

[VentZer0]

Does the velocity curve even matter for this mod or does it just say: Ok disregard vel-curve. Your engine should consume so much fuel, you are going with X% of max rated speed for this engine, when X% gets near to 1 then overheat engine? (I assume thats vastly oversimplified ^^ but I would like to know how it actually works). In reality engines dont overheat when you get close to their max speed, do they? I am not sure about it, but afaik they produce just less thrust the faster you go, so making them overheat is just a way of workaround? However, I know that engines irl can very much overheat too.

I googled the engine specs - took some time, I had to rely on guessing for some of the specs on the the F119, F135, and the AL41F1S because those are state of the art engines where people seem to be very hush hush about the specs alone, didnt even find bypass ratios for one engine. In the mod the F119 is shown with a thrust of 250kN, in reality that is ~100kN less actually, the TWR and Thrust are known for the F135 and F119 engines, they are essentially the same engine with some modifications to it (F35 non STVOL version).

Well I know that the its physically speaking not complete, but it might help. I dont think you would get any specific Thrust to Altitude data on legal ways about those engines, I would assume they are OPSEC stuff i.e. top secret.

I know the website where OP got that velocity to thrust plot from, read that myself on my research for this, because I have incomplete data I turned to use a sigmoid curve to model the velocity curve for KSP. It depends on the individual aspects of the engine, specific impulse, thrust, SFC, BPR, weight, ..etc the formula is shown in the PDF. It might not be accurate for serious aeronautics but at least balances the engines against eachother depending on their performance you would derive from their specs.

In any case we need a third curve definition for KSP especially for Jetengines, thrust to altitude.

[camlost]

Take your time to use NASA EngineSim, play with this mod, read the code and cfg, or try AJE Tester.exe that's included. I trust that you can figure it out since you did this research and fitted the data to a curve.

In short, what you did is actually incompatible to the existing approach. It's easier for you to try it than for me to blab here.

I dont think you would get any specific Thrust to Altitude data on legal ways about those engines,

True, but thrust and Isp MUST BE two-variable functions nonetheless, hence they need maps instead of curves. The difficulty is why I chose NASA EngineSim code in the first place.

[blowfish]

You're correct that the velocity curve and other default engine parameters don't matter under AJE. The piece you're missing is that AJE calculates thrust and SFC based on thermodynamic equations coming from the various pressure ratios and other engine parameters rather than fitting some curve.

[VentZer0]

You're correct that the velocity curve and other default engine parameters don't matter under AJE. The piece you're missing is that AJE calculates thrust and SFC based on thermodynamic equations coming from the various pressure ratios and other engine parameters rather than fitting some curve.

Thats why I was asking how it works in the background. Basically, I started at zero, I have no knowledge of how Unity works or how to do something like AJE for KSP, I have basic IT know how. So I saw the config files for engines and played around, googled the rest and wasted a day trying out. I even had chat with my physics professor (yep, I study physics) about Isp and other things. It soon was clear that vanilla KSP doesnt let you apply any realworld physics approach to model jet engines. So I just fitted some curve

[VentZer0]

Take your time to use NASA EngineSim, play with this mod, read the code and cfg, or try AJE Tester.exe that's included. I trust that you can figure it out since you did this research and fitted the data to a curve.

In short, what you did is actually incompatible to the existing approach. It's easier for you to try it than for me to blab here.

True, but thrust and Isp MUST BE two-variable functions nonetheless, hence they need maps instead of curves. The difficulty is why I chose NASA EngineSim code in the first place.

Yes. I realize that, I saw that you did something completely different when I saw the standard vel and atmo curves in the cfg-files. Since I just went ahead with my limited knowledge and basically just tweaked the curves, you did something else.

I just thought that you could implement the data I gathered into your mod - not the curves I created - you know moar engines!

But I see that AJE Tester has a lot more things to input than I have data about the engine. Oh well.

[djnattyd]

For some completely unknown reason all the props in the KAX pack have suddenly developed a thrust output of 5.0. Even with Hack Gravity turned on, they can't move anything.

[NathanKell]

AJE needs to be recompiled every time FAR updates.

[Guest]

When is the next AJE version expected? Aside from a FAR recompile, Camlost is sitting on some RetroFuture engine configs that would be really handy for me.

[djnattyd]

When is the next AJE version expected? Aside from a FAR recompile, Camlost is sitting on some RetroFuture engine configs that would be really handy for me.

You think that's bad? I've got a long haul prop-driven plane designed to complete a ton of FinePrint survey contracts that's gonna have to be grounded until the recompile arrives

[blowfish]

The most recent commit on GitHub is a recompile from 12 days ago - 2 days after the most recent version of FAR was released. I'm not sure if that was included in the recompile but there's a fair chance it was.

[camlost]

I don't have any new engines configured. Usually I only make configs when and if I want to play it. I haven't played with propellers for a while so I didn't even notice the incompatibilty with FAR.

That said, you guys need to participate more. What's the point of being open-source?

[Guest]

I don't have any new engines configured.

Well, what I've seen here: http://forum.kerbalspaceprogram.com/threads/100553-Advanced-VTOL-Control-System-v0-1-Nov-18?p=1549719#post1549719 seems to imply otherwise You've got at least the lift fan and F-35 engine configured, this is not in the current release.

[djnattyd]

...That said, you guys need to participate more. What's the point of being open-source?

I'd love to contribute but I don't know enough about either modding KSP or engine profiles to be of use.

[camlost]

I'd love to contribute but I don't know enough about either modding KSP or engine profiles to be of use.

I didn't know anything about it a year ago.

[blowfish]

That said, you guys need to participate more. What's the point of being open-source?

For me, I think a lot of the barrier is not knowing what the parameters mean/what they affect. Part of that has been a Java issue which prevents me from using EngineSim (and by extension its built in documentation). I've been over the cfgs and much of the codebase multiple times, and I've got a few ideas for additions I'd like to make, but not understanding how everything interacts is a barrier to implementation.

One of the features I've been thinking about is variable bypass engines (similar to the YF120/proposed ADVENT engine). It looks like it would be pretty easy to vary the core area/bypass ratio, but would some compressor parameters also have to change as well?

[blowfish]

Also, is there a formal process for proposing cfg additions?

[camlost]

There's no formality, just post or push on github whatever you have

[aikixd]

Is it ok that the engines give around three more times thrust than before? My plane that was taking of after around 20 seconds from the start now takes less than 10 seconds and goes supersonic a few seconds later.

[blowfish]

Is it ok that the engines give around three more times thrust than before? My plane that was taking of after around 20 seconds from the start now takes less than 10 seconds and goes supersonic a few seconds later.

I think it's normal. You get a lot more thrust at sea level but the thrust drops off very quickly with altitude.

[Guest]

Yeah, this is especially good news for jet VTOLs, which now get a lot more thrust to spare. It makes spaceplanes harder, though, as thrust drops off very rapidly with increasing altitude.

[aikixd]

I also noticed many new engines appeared in the tech tree with different thrusts. Comparing the weight to thrust ratios with real planes made sense. It's just the engines that were installed on the 15 ton plane converted into 14000+ kg/s engines, which made me wonder.

[BNSF1995]

Will this mod allow Realism Overhaul to work with just the DLL? Or do the parts need to be installed as well? I ask because I don't want any parts I don't need sucking up my memory (and memory is something I'm seriously watching).

[Camacha]

I think it's normal. You get a lot more thrust at sea level but the thrust drops off very quickly with altitude.

Is there a particular reason for this change? Was the model flawed before?

[NathanKell]

Yes. Jets don't get magicair in real life. Think about what a jet does: it compresses and burns the ambient air. When you go higher, and there's less air to burn, you get less thrust. Except in KSP.

[Hodo]

Yes. Jets don't get magicair in real life. Think about what a jet does: it compresses and burns the ambient air. When you go higher, and there's less air to burn, you get less thrust. Except in KSP.

Unless you are going faster and managed to maintain the same dynamic air pressure for the craft at the new altitude.