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

[Genius Evil]

Unfortunately, the problem persisted after removing those modules. The drag coefficient seems to be almost random for each engine -- 0.06 for the R-2600, 0.13 for the Griffon, and 0.18 with the Liberty L12. I'm going to try re-installing AJE and FAR, and if that doesn't work I'll decrease the surface area of my engine's FARBasicDragModel.

[blowfish]

Purely out of curiosity, I plotted the TPR curves for the AJE inlets.

Of course, the interpolation is linear rather than KSP's float curves, so don't take any exact values too seriously (except for the marked points), but you can generally get a pretty good idea of how different inlets behave at different speeds.

[Genius Evil]

Reinstalling AJE, FAR, and Firespitter didn't change anything. Decreasing the surface area from 14.5 to 1 in the FARBasicDragModel decreased the zero-lift Cd to ~0.95. I'll try a clean install with just AJE, FAR and Firespitter tomorrow.

[Van Disaster]

Just got round to trying this - went back a few pages but didn't find anything concrete, I presume my SABRE Ms should not be hitting 2.1MN thrust on the runway...

[Genius Evil]

Okay, I got the drag issue sorted out. I copied "Twin Cyclone.cfg" (I chose this one because it displayed a reasonable Cd value in game) and replaced the name, title, description and AJEpropeller module. It appears that there was some sort of problem with the R-2800's cfg, since it also exhibited the extremely high drag coefficient. Anyway, when I re-engined my Corsair with the R-4360 it had a zero-lift Cd of ~0.01-0.02. It was able to reach 720km/h at 2000 meters, so it's performing properly now.

[NathanKell]

Awesome!

I haven't gone through those configs since ferrram update FAR's drag code, so I'm not sure what's wrong.

That said, if you want spot-on Cd0, go to the Stability / Stats tab of analysis, set density to something high, and calculate.You might also want to lower mach. That'll approximate the Cd0 with pretty good precision. (And thank ferram for adding Cd display to it )

[Genius Evil]

I did use a low mach number, but I didn't think of increasing the density -- thanks for that tip. I actually couldn't find a single difference between the cfgs; they were the same letter-for-letter as far as I could tell. I have absolutely no idea why one had normal drag and the other extreme drag. I'll go through all the engines tomorrow and see which ones are broken, then fix those.

I've been thinking about how poorly the Firespitter models represent the real engines and propellers. I'm going to mock up some propellers, spinners, and radial engine fronts, and see if I can use cfg welding and FSTextureSwitch to make fully customizable engines. The cfg for one would look something like this:

	MODEL
	{
		model = customprops/4blade
		scale = 1.5, 1.5, 1.5
		position = 0.0, 1.1, 0.0
                texture = cproptex/dark
	}
        MODEL
	{
		model = customprops/radialbody1
		scale = 1.3, 1.3, 1.
		position = 0.0, 1.1, 0.0
                texture = cengtex/radial1.
	}

MODULE
 {
	name = FStextureSwitch
	moduleID = 0	
	textures
	{
		Planetex/Green
                Planetex/Red
                Planetex/Blue
	}
	objects
	{
		name = Engine_Body
	}

[NathanKell]

That would be great! Nli2work made me a set of generic spinner+prop that I meant to get working but never did. They might be of use to you. PM her/him (and mention me), maybe?

[Genius Evil]

It was available for download from the RetroFuture thread. Having this means I don't have to figure out how Firespitter props work by trial and error! Thanks for mentioning it! I don't think FSMeshSwitch will be able to do what I need though, since it can't rescale meshes.

[Genius Evil]

Just an update on the custom prop project. Tests showed that Firespitter props made from multiple models are possible, so I can definitely do it -- it's just a matter of getting the models done. I've started working on some, but I probably won't have anything complete until after final exams.

[icecubecookie]

btw is there any conflict between FAR ver 14.4 and AJE v1.6.5 or is the simulated thrust by the thrust calc provided not updated?

right now when i'm making planes, they are underpowered for 1:1 TWR, when i use the thrust values provided by the in game parts, and when i use the calc, the thrust values are different from the given values in game, and are also pretty different from actual in flight values

eg. 1000m alt, 300m/s test speed, 100% full afterburner, gross thrust was around 10% lower than the calc's value, useful thrust even lower than that (normal), intakes are in excess, so no intake area requirement shortage.

edit* :whoops i see the problem

did not see the TPR differences for intakes

might want to have something added to the mod to calculate the thrust levels with respect to intakes

sorry for the false heads up >.<

Edited November 30, 2014 by icecubecookie

[camlost]

Needs some opinions on the engine in this mod http://forum.kerbalspaceprogram.com/threads/97525-WIP-Large-Diameter-Space-Plane-Parts-V1-4

@icecube, also Kerbin's atomosphere density and temperature is different from the earth, that makes some difference too

[blowfish]

Needs some opinions on the engine in this mod http://forum.kerbalspaceprogram.com/threads/97525-WIP-Large-Diameter-Space-Plane-Parts-V1-4

That one's tough, especially since the description and stats aren't really based on any real engine. The obvious starting point is a beefed RAPIER, but that's not particularly interesting. What sort of variation does AJE allow beyond the prat3 curve?

[Guest]

I think it should be a heavy, bimodal jet. A very advanced one, it looks SF-ish, so perhaps it should behave like this (while not really being outside the realm of possibility).

[camlost]

More specific suggestion is appreciated, as always

[blowfish]

Maybe something resembling a cross between the J58 and the RAPIER? Although again I'm not quite sure what major benefit it would have over the pure RAPIER - an afterburner thrust boost and better low-mach efficiency?

[NathanKell]

You might consider using a much more agressive prat3curve than the SABRE, as otherwise you'll top out below Mach 5--you need the final CPR to be 1.0 for full turboramjet effect.

[Ph34rb0t]

Can this be used without the MM configs? Or does anyone have configs tailored around other engines? Or does this even work with NEAR (aka FAR minus supersonic stuff)?

I'm really trying to like this mod as it fixes the very weird jet engine behaviour of stock KSP, but the included engines are just much too overpowered for my purposes.

My 14.5t sciencejet (straight wings) still accelerates with two wee J85s limited to 60% and throttled to 70% while flying more than 500m/s (mach 1.8).

[NathanKell]

If you play without mach effects, expect high supersonic speeds. There really isn't much that can be done about that: if you remove high supersonic drag, then you remove what prevents you from going really fast.

What do you mean by "without the MM configs"? Then you won't have the AJE modules added to any engines...

[Guest]

I've just had an idea. It seems that there is a "precooled" flag in the engine config. How about making a new "precooler" module that, if present on a part the engine is attached to, would set this flag on that engine? The flag should still be there, for example for engines with an integrated precooler, but for most, it'd be handled by a separate part. Also, I don't think this would need any fancy flow logic, just a simple attachment check.

[blowfish]

Needs some opinions on the engine in this mod http://forum.kerbalspaceprogram.com/threads/97525-WIP-Large-Diameter-Space-Plane-Parts-V1-4

May I recommend also including the engine from this mod? In this case a beefed RAPIER is precisely what is needed.

[camlost]

I've just had an idea. It seems that there is a "precooled" flag in the engine config. How about making a new "precooler" module that, if present on a part the engine is attached to, would set this flag on that engine? The flag should still be there, for example for engines with an integrated precooler, but for most, it'd be handled by a separate part. Also, I don't think this would need any fancy flow logic, just a simple attachment check.

That flag doesn't do anything. Also I don't understand the mod makers' minds, would an engine that's supposed to have a precooler, still function without it? That's not really a design choice.

[VentZer0]

I would like to contribute something to this, since I am more into Airplanes than Space, I built a lot of Jets in KSP. The problem with the engines bugged me alot aswell. So I got to work on some turbojets and turbofans myself. I Researched the specs of a couple of engines namely the GE F110 series 100/129/132/400, PW F119-100, PW F135-100, PW F100-229, Saturn AL31F/FM/FP/AL41F1S, so F16,F14,F15,F22,F35,Su27/34/33/38,Su50.

How would I need to incorporate the specs to your mod?

https://drive.google.com/file/d/0BwXhQ9I28t2tRFBmWGhqdGpzX2s/view?usp=sharing

This is the PDF I made in excel to have a velocity thrust curve that balanced the engines against eachother, the specs determine the curve and soon, the actual equation is in the PDF.

[blowfish]

The F100, F119, and F135 are already included.

[camlost]

I would like to contribute something to this, since I am more into Airplanes than Space, I built a lot of Jets in KSP. The problem with the engines bugged me alot aswell. So I got to work on some turbojets and turbofans myself. I Researched the specs of a couple of engines namely the GE F110 series 100/129/132/400, PW F119-100, PW F135-100, PW F100-229, Saturn AL31F/FM/FP/AL41F1S, so F16,F14,F15,F22,F35,Su27/34/33/38,Su50.

How would I need to incorporate the specs to your mod?

https://drive.google.com/file/d/0BwXhQ9I28t2tRFBmWGhqdGpzX2s/view?usp=sharing

This is the PDF I made in excel to have a velocity thrust curve that balanced the engines against eachother, the specs determine the curve and soon, the actual equation is in the PDF.

How did you find the data? This mod uses a different method from defining thrust curves etc. Instead, the engine is defined by components like turbine temperature and compressor ratio. Then calculate the engine performance with thermodynamics.

Even if a numerical method is applied, your data is still incomplete for serious aeronautical simulation. As explained in OP, both thrust and SFC depend on altitude and speed at the same time.