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

[MAKC]

This was all the info I could find after trawling through obscure Russian sites with Google Translate:

D-30F6

Military thrust (H = 0, M = 0, tn = 15 º C, ÃÆ’ in = 1.0)

Thrust: 9500 kgf (~93 kN)

Specific fuel consumption, kg / kgf h: 0.72

Full afterburner mode (H = 0, M = 0, ÃÆ’ = 1.0 input)

Thrust: 15500 kgf (~153 kN)

Specific fuel consumption, kg / kgf h: 1.9

Max airspeed: M2.83 (before risking damage to compressor, should be possible to go higher with risk of overheating)

Max turbine inlet temperature: 1386 C

Dry weight: 2.416 t

Low-pressure compressor:

Stages: 5

Compression ratio: 3.00

Bypass ratio: 0.57

High-pressure compressor:

Stages: 10

adjustable stator blades of the first stage,

the degree of compression of air 7.05 total pressure ratio of 21.15.

The combustion chamber 12 trubchatokoltsevaya gas pipes.

High pressure turbine: 2 steps, Tt = 1367 ° C, cooling air is taken from the blades 5 and 10 compressor stages.

Low pressure turbine 2 stage.

Edited March 22, 2014 by MAKC

[MAKC]

Why was the requirement for air intakes removed? Will it ever come back?

[Guest]

Would that be possible to add precooler simulation? Basically, a part that would greatly increase the temperature at which the compressor overheats, by cooling the intake air down. Also, why did you remove the intake requirement? Are you going to implement them in some way later? B9 has a lot of interesting ones, I'd like to be able to use them.

I have an idea how to implement both, actually. With intakes, make each engine require a certain intake area. Exceeding it should not cause a performance increase, but not meeting it would cut into the maximum fuel flow you can introduce into the engine. Each intake has to be connected to the engine via a structural part (i.e. not a wing or a fuel tank).

Now, precoolers. They'd have to be located somewhere on the structural path from intake to the engine. Each precooler would reduce the engine heating by a certain factor (configurable in it's module), by cooling the air introduced into the engine. Their effects should probably stack, so make them heavy to compensate.

As for drag problems with intakes, just remove the stock intake module via MM and insert your custom one. It'd be nice if closing the intake only decreased drag on select B9 intakes that have an animation to go with it.

Edited March 22, 2014 by Guest

[camlost]

I removed intake requirement simply because it serves no purpose. The stock physical model uses intakes as some kind of operation ceiling, which is implemented by AJE in a much more realistic manner. The problem is, with the corrected fuel flow, you need a lot of intake air, and the engines will automatically throttle down when it is insufficient. So the air intake physical model serves no real purpose but a negative effect that is not wanted and hard to predict. In previous versions I tried to increase the intake area and resource of intakes, but for some high-altitude high-speed designs there's still the problem

Currently, intakes have no drag(both stock and FAR if you use v0.13) and no purpose, but you can still use them anyway you like. If inlets are to be modeled in a realistic manner, we must consider 1) total pressure recovery, which depends on Mach number and angle 2) drag, which includes friction drag and shock wave drag, mind you that the oblique inlets could have very complicated, multiple shock waves. Simply requiring a minimal area is 1) not realistic 2) too easy since they have no drag 3) this is a sandbox game that allows player to alter anything so there's no real banning of cheating behaviour

How do you decribe precoolers in exact terms? They are not magical energy black-holes. Seems to me they are simply moving heat/work from before the compressor to after the compressor, right? Wouldn't it be equal to an elevated compressor max temperature? Of course, the precooler part is just a placeholder.

[camlost]

@MAKC

If you replace AJEModule in the B9 turbojet for this, you should get something close to D-30F6

MODULE

{

name = AJEModule

IspMultiplier=1

defaultentype=2

defineenparm= true

acore=5.5

byprat=0

prat3=20

tt4=3000

tt7=6200

abflag=1

fhv=18600

eta7=0.8

tinlt=1300

tfan=1500

tcomp=2700

}

[Guest]

It could be very interesting (though no doubt hard to model) all the neat effect on the intakes. Especially during supersonic flight, it'd probably add a lot of depth to plane construction. You'd not only have to consider the amount of intakes, but also their placement and type.

How do you decribe precoolers in exact terms? They are not magical energy black-holes. Seems to me they are simply moving heat/work from before the compressor to after the compressor, right? Wouldn't it be equal to an elevated compressor max temperature? Of course, the precooler part is just a placeholder.

Yes, that's basically how I'd like them to work. A precooler mounted before the engine should raise the maximum temperature compressor by quite a bit. They're basically removing heat from the compressor and radiating it away, probably shunting some into fuel (it's cryogenic, so it's usually used as coolant), too.

[NathanKell]

camlost: Alas I am not an engineer. I thus have two questions for you (and a bonus non-engineer question).

1. is there a single parameter that will, roughly, scale thrust? It appears like maybe acore does this? (Trying to figure out the difference between the J47 and J85 configs).

2. Is there a way to emulate a J58, or, even better/also, a full-on turboramjet?

Bonus question: how do I go about swapping from ModuleEngines to ModuleEnginesFX? Do I just change the name of your module and change the underlying module(s) so they're like the ones in AJE.cfg, or is it more complex? (I'd like to do this for the B9 jet, which IIRC nazari already has a HotRockets config for, and the FS tailjet, which I guess I might make a config for).

[camlost]

camlost: Alas I am not an engineer. I thus have two questions for you (and a bonus non-engineer question).

1. is there a single parameter that will, roughly, scale thrust? It appears like maybe acore does this? (Trying to figure out the difference between the J47 and J85 configs).

2. Is there a way to emulate a J58, or, even better/also, a full-on turboramjet?

Bonus question: how do I go about swapping from ModuleEngines to ModuleEnginesFX? Do I just change the name of your module and change the underlying module(s) so they're like the ones in AJE.cfg, or is it more complex? (I'd like to do this for the B9 jet, which IIRC nazari already has a HotRockets config for, and the FS tailjet, which I guess I might make a config for).

1. acore is directly proportional to thrust, however allowing to change this is kind of cheap. The best thing is probably to change the compression ratio (prat3) and turbine temperature (tt4). These two affect thrust, isp and velocity curve. Also that's what happens in RL when, for example a better material is invented. Is there an API like RF's techlevel scaling but allows tweaking two parameters?

2. Not directly. The best thing I can think about is having two AJEModules, one is a turbojet and the other one a ramjet. Air flow needs to be distributed between them by some mechanism.

3. A turboramjet is mathematically equal to a turbojet with afterburner and low prat3 and tt4

4. Wait for the next version that's coming soon. The B9 turbojet seems fine. But does the f-119's smartgimbal module support FX? The two high-bypass turbofans requires firespitter.dll to animate and they shouldn't be having scorching exhaust anyway. That's why I'm not using FX yet. But with next version, you should be able to convert anything into FX by simply renaming AJEModule to AJEModuleFX.

[NathanKell]

1. There is not yet such a thing. On my long-term list is writing a "Generic TL module" that will change arbitrary values in other modules based on tech level, but I haven't done it yet.

2/3: Sorry, not sure what's answering what. First you say can't be done, then you suggest lowering prat3 and tt4? Let me re-ask if I might:

2. How might one simulate a J58 (SR-71 engine)? And/or other turbojets with adaptation for very-high-speed (Mach 3+) flight? (engines of MiG-25 or XB-70).

3. How might one simulate a true combined-cycle turboramjet?

4. Cool. (Gimbal modules operate independently of engine module type.)

[Hodo]

I look foward to what you two come up with here in the future. I really like this mod, even though I am not currently use it, and I agree 120% KSP jets are WAY to powerful.

[Justin Kerbice]

I'll try your work camlost, as I don't like how stock engine use more fuel when our plane is higher (AFAIK, real life plane need to go higher to suffer less from drag AND save fuel, in KSP, we should better fly at sea level ).

I just wonder why HotRockets! FX plugin is a requirement (it's just "cosmetic", isn't it ?)

[InfinityArch]

Is the overheating simulated by this distinct from the overheating caused by KSPI at high speeds due to ram pressure heating, and if not, are they compatible?

[camlost]

1. There is not yet such a thing. On my long-term list is writing a "Generic TL module" that will change arbitrary values in other modules based on tech level, but I haven't done it yet.

2/3: Sorry, not sure what's answering what. First you say can't be done, then you suggest lowering prat3 and tt4? Let me re-ask if I might:

2. How might one simulate a J58 (SR-71 engine)? And/or other turbojets with adaptation for very-high-speed (Mach 3+) flight? (engines of MiG-25 or XB-70).

3. How might one simulate a true combined-cycle turboramjet?

4. Cool. (Gimbal modules operate independently of engine module type.)

The J58 has a air-bleeding feature, that means its compression ratio is variable, which cannot be simulated by NASA engineSim directly. A turboramjet is basically a turbojet with a low compression ratio, at least mathematically it can be described with the same thermodynamic equations. So they are not the same thing. The engines for Mig-25 and XB-70 are basically just turbojets. Their problems were mostly regarding material.

[camlost]

Is the overheating simulated by this distinct from the overheating caused by KSPI at high speeds due to ram pressure heating, and if not, are they compatible?

I'm not sure what KSPI does.

I'll try your work camlost, as I don't like how stock engine use more fuel when our plane is higher (AFAIK, real life plane need to go higher to suffer less from drag AND save fuel, in KSP, we should better fly at sea level ).

I just wonder why HotRockets! FX plugin is a requirement (it's just "cosmetic", isn't it ?)

I think most of the KSP community is all about cosmetic things

I look foward to what you two come up with here in the future. I really like this mod, even though I am not currently use it, and I agree 120% KSP jets are WAY to powerful.

Is there any specific problems you are having?

[Hodo]

I'm not sure what KSPI does.

Is there any specific problems you are having?

I really like KSPI, but only the pre-cooler parts for the intake system for air breathing jet engines. I wish they could be implemented to the SABRE precooler structure part.

I currently have only one problem, not enough time. I am currently trouble shooting some plugin issues on my current install then fixing them and reinstalling them. Hopefully I will have it fixed tonight....hopefully.

If I can get everything, working I look foward to trying your mod again.

[NathanKell]

KSPI sets part eat each tick, so it clobbers the heat value anything else (engine heat production, DRE, whatever) applies.

camlost: ah, thanks! Given one can't model that aspect of the J58, how would you suggest going about configuring a (non-pure-ramjet) engine for Mach 3+ flight?

[camlost]

KSPI sets part eat each tick, so it clobbers the heat value anything else (engine heat production, DRE, whatever) applies.

camlost: ah, thanks! Given one can't model that aspect of the J58, how would you suggest going about configuring a (non-pure-ramjet) engine for Mach 3+ flight?

This

Or try the new J93. TET and CPR have great effects on the "velocitycurve".

TET: turbine entry temperature

CPR: compressor pressure ratio

[NathanKell]

Ah, cool! Thanks.

[Tidus Klein]

Coming over from FAR thread:)

i really think that an alternative MM confg, to skip real fuels would be great for this. and its not that hard, I just did it

PS still trying RF thou, I think im learning to like it.

I just had to relearn flight because now I cant go from 0 to mach 5:( all my SSTO's are borked now

Edited March 28, 2014 by Tidus Klein

[camlost]

@NathanKell,

AJEModule supports ME and MEFX now.

[NathanKell]

camlost: dang, you're updating nearly faster than I can keep track!

A suggestion if I might: I went ahead and did a bit of a switcheroo, using the B9 turbojet as the D-30F6 that it's IIRC supposed to be (using that config you posted), the stock advanced jet as the J93, and Taverio's ramjet as the ramjet. Does that make sense to you, or do you want to keep a ramjet accessible to all the stock players?

I've also tried to make an Avon and a Nene, but I don't know enough to change the pressure/heat/etc, so I just modeled them by changing the thrust of the J79 and J47 a bit. Also the J57 (which seems quite close in performance to the Avon). If you have better stats I'd love to see them.

A site that seems useful: http://www.jet-engine.net/miltfspec.html

I have to go through and rebuild all my old planes, too, now that AJE is in. For a taste, check out the last two here. The first is a mashup of a Voodoo (twin J57s), a Mirage, and who knows what; the second is a Voodoo's wings on a Starfighter. I'm wondering if the limit there is the compressor for the J79; it overheats well before Mach 2.5, which is IIRC the Zipper's max. Could also be the wings though.

[camlost]

Wow, you have an impressive fleet. Where did you get the cockpit for the last one?

A suggestion if I might: I went ahead and did a bit of a switcheroo, using the B9 turbojet as the D-30F6 that it's IIRC supposed to be (using that config you posted), the stock advanced jet as the J93, and Taverio's ramjet as the ramjet. Does that make sense to you, or do you want to keep a ramjet accessible to all the stock players?

First of all, the D-30F6 should have byprat=0.57. And what's the difference between that and F-100? In the future, I may make something to allow choosing engine parameters in the editor, very much like what PP does. It will save many engines in one xml probably. Then you can choose any afterburning turbojet/low bypass turbofan to replace the stock jet. I think the stock turbofan should remain some kind of ramjet, its nozzle 3d model is quite special. May be it should choose from ramjet, turboramjet, or scramjet if that's figured out. Any other ideas? Any ideas on the RAPIER?

But I'll be very busy for a few months. And I'm not a coder anyway. If somebody want to contribute I'll be happy to discuss about it.

I've also tried to make an Avon and a Nene, but I don't know enough to change the pressure/heat/etc, so I just modeled them by changing the thrust of the J79 and J47 a bit. Also the J57 (which seems quite close in performance to the Avon). If you have better stats I'd love to see them.

Seems to me completely copying historical airplanes can be futile. Even if you have the exact same engine thrust, you may not have the exact same size of fuselage and wings. Let along that 3rd generation and after fighters usually take advantage of induced vortices which FAR doesn't model. Also FAR has only one airfoil so some subsonic designs can be weak too.

Personally I like thinking like a designer. Set up goals for max speed, weight and range, then choose engines and geometry. From that viewpoint, engines from roughly the same era and same purpose are very similar. By "purpose" I mean CPR. A high-CPR (>20) favors subsonic thrust and efficiency, and a low-CPR favors supersonic thrust and efficiency. Ramjet as no CPR, and its best performance is >Mach 3. Generally you always want a higher TET, and that represents "era".

[NathanKell]

Thanks! That's from Mettworks, in the Dev forum. But it's clipped inside some stretchies such that only the canopy is showing.

I suggested D-30F6 because iirc that's what it was modeled on. And a turboramjet makes the most sense.

Oh, I definitely wasn't trying to exactly clone real craft--the only clone I've made was of the Sabre, and it flies just about right, although since FAR doesn't model the area rule and the need for it it out performs the real thing, going barely supersonic. But for RftS I want multiple nations' jets and at various tech and power levels, so...(Britain, US, Russia, Germany). Helpful re CPR!

[Dirt_Merchant]

Nice planes Nathan, you've given me some motivation to get my old stuff out and get it dialed. I'll now have to get crackin' on a collection of prop/turbo-prop engines for my general aviation planes, seaplanes, aerobatics, firebombers and cropdusters. Expect a PW pt-6a, and lycoming 540 engine config in the next couple days! I'll probably also include one for the garret t76/tpe331 turbine, and one for the good ole' wright radial 3350 for some Rare Bear radness;) Also Nathan do I notice a fstextureswitcher module on your pwings?

[NathanKell]

Thanks!

Aw yiss, F8F time. The Iron Works knew how to build 'em...

Yes, yes you do. I need to make ones for brushed aluminum and X-15-black. I also need to enable it for proc surfaces and proc wing ends.