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[1.5.1] Advanced Jet Engine v2.12.1 (Nov 11)


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@blowfish yes, we don't have a lot of data, because the engine is still in R&D! But with the config we currently have, the skylon is totally un-orbitable. According to REL, the S.A.B.R.E. should have great performance at a wide range of speed and altitude. Therefore it needs to have a not-too low thrust on the ground (as you said ~700kN) and then to rise to an higher thrust (~1900kN, still from wiki = 1.3 TWR in mid flight) between mach 1-2 and mach 5. After mach 5 the thrust should start to decrease and be almost null at mach 5.5.

 

For the ISP there is little to no data for the S.A.B.R.E. but there is data for the A2 : TSFC = 40.9kN.s/kg at Mach 5 and 96.0kN.s/kg at Mach 0.9. It don't know if this will help but the SABRE has probably similar performances.

By formula, this is between 4186s and 9473s.

EDIT: not sure at all of my calculation.

Edited by Zarbizaure
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Might not be realistic, as we can't even proper data to compare, but I don't think SABRE is too underpowered.
 It gives some different caracteristics compared to other engines, and if you understand them, SABRE can be quite usefull.

It have high mass, compared to other engines, but it is quickly compensated on larger crafts due to higher ISP, if you have a lot of fuel on board.
Next, you need to look at highest thrust and velocity where it is achieved. It is around 3.8 Mach IIRC. You need to design craft for a stability near 24-26 km, so you can achieve max speed in airbreathing mode (26 km is limit due to oxygen cut off). When RAPIER for example loose thrust rapidly near that velocity, SABRE achieve max, giving that so much needed push before switching to rocket mode.

Need to be carefull, though, as around 24-30 km you can't travel for a long on high velocity due to overheating, but it will give you that push to gain more vertical speed jsut before switching to rocket mode.

All in all, SABRE have it's own unique role in terms of gamebalance in KSP.

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in stock, the SABRE is not a problem. But with realism overhaul...if you don't have the right stats, an SSTO is impossible. I'm not asking to modify the part for stock, just for RO. My skylon is as close as possible to the original: 330T start mass, 55T dry mass, 6.8km/s in closed cycle mode...The only problem is the air-breathing part. Flying a monster like the skylon with only 2*450kN of thurst is REALLY hard. That's why we need realistics stats for RO.

And a longer runway too.

Edited by Zarbizaure
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@Zarbizaure So here's how things stand now

  • The Isp of the SABRE in AJE is almost certainly too low, I will be addressing this.
  • The thrust isn't as high as the real thing, but it's also a much smaller engine than the real thing.  In KSP it's 2.5m, the real thing is more like 3.8m at the intake and 5m at the nozzle.  It should probably be rescaled and up-thrusted but that's really RO's domain and not AJE's.
  • The mass is still unknown, and that's a very important stat, especially in RO.
  • If you look at REL's website, they have downrated the max takeoff mass to 275t.
  • The Skylon employs a lot of design characteristics that may not be possible in KSP.  It has very stubby wings which mean the takeoff speed is quite high (but drag is minimized), and it is probably aerodynamically unstable.
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I thinks the standard SABRE is good, but the RO SABRE only needs to be changed. I'll update my PR to change its size. (Really? it's 5m width?)

I just need some better configs for the AJE parameters.

About the wings: with FAR and B9 procedural wing, the design is really stable. It has a really high liftoff speed (about Mach 0.5 or 160m/s) but it fly well. The only problem I have in air-breathing mode is the lack of thurst. Even the canard wings work fine in RO and provide a good amount of pitch.

About the mass: yes, that's the unknow but important factor...it's set to 8T in RO, I suppose it's a bit high. A similar engine with the same thurst level would be the RS-25; and the RS-25 weights 3.2T. Even if it will have a higher mass with the precooler mass, it should be around 4-6T.

The 275T mass is for the skylon C1; the sylon D1 will be a bit heavier.

Edited by Zarbizaure
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@Zarbizaure It's about 5m at the nozzle, yeah.  But it's not constant diameter.

If you want to increase the thrust, you need to increase the Area parameter in ModuleEnginesAJEJet, and correspondingly on the intake (note that this is different than lower case area).

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Inlet. Each engine requires a minimum inlet area (see right click menu in editor). Make sure you have enough inlet till you see "Inlet Area:100%" in flight. Each inlet has a TPR(total recovery pressure) that is dependent on Mach number and angle of attack. Avoid TPR loss by facing the inlet to the freestream.

Is this still accurate? Right-clicking the part in-editor tells me nothing about it's air requirements, and right-clicking it in the parts list tells me e.g. "Intake Air: 10.114/sec. Max." but with no mention of "inlet area". The intakes, on the other hand, tell me "Intake Area" in square meters, "effective base speed" in m/s, "intake Atm amount" with no units and "intake air amount" with no units, but nothing in the same units as the "intake air" stat on the engine. I also can't see any in-game mention of "total recovery pressure" or "TPR" or any inlet area percentages.

Am I missing something? Because I'm really not understanding how you're supposed to work out if you have enough inlets...

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1 hour ago, baldamundo said:

Is this still accurate? Right-clicking the part in-editor tells me nothing about it's air requirements, and right-clicking it in the parts list tells me e.g. "Intake Air: 10.114/sec. Max." but with no mention of "inlet area". The intakes, on the other hand, tell me "Intake Area" in square meters, "effective base speed" in m/s, "intake Atm amount" with no units and "intake air amount" with no units, but nothing in the same units as the "intake air" stat on the engine. I also can't see any in-game mention of "total recovery pressure" or "TPR" or any inlet area percentages.

Am I missing something? Because I'm really not understanding how you're supposed to work out if you have enough inlets...

There should be an Area stat of the inlet, both in the part catalog and the right click menu.  You basically just need to have as much intake area as engine area.  If you click for more info in the part catalog, the intakes will also tell you what sort of speed range they're optimized for.

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  • 3 weeks later...

Changes to Firespitter directories have resulted in some AJE parts dependent on FS models not being created:

[ERR 23:59:41.573] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine/model' as model does not exist

[ERR 23:59:41.574] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.574] PartCompiler: Cannot compile model

[ERR 23:59:41.574] PartCompiler: Cannot compile part

[LOG 23:59:41.574] PartLoader: Compiling Part 'AJE/Parts/Props/M63/ShvetsovM63'
[ERR 23:59:41.578] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine2blades/model' as model does not exist

[ERR 23:59:41.579] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.579] PartCompiler: Cannot compile model

[ERR 23:59:41.579] PartCompiler: Cannot compile part

[LOG 23:59:41.580] PartLoader: Compiling Part 'AJE/Parts/Props/M82/ShvetsovM82'
[ERR 23:59:41.583] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngineElectric/model' as model does not exist

[ERR 23:59:41.584] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.584] PartCompiler: Cannot compile model

[ERR 23:59:41.584] PartCompiler: Cannot compile part

[LOG 23:59:41.585] PartLoader: Compiling Part 'AJE/Parts/Props/MercuryIX/MercuryIX'
[ERR 23:59:41.589] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine2blades/model' as model does not exist

[ERR 23:59:41.589] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.590] PartCompiler: Cannot compile model

[ERR 23:59:41.590] PartCompiler: Cannot compile part

[LOG 23:59:41.590] PartLoader: Compiling Part 'AJE/Parts/Props/MercuryXV/MercuryXV'
[ERR 23:59:41.594] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine2blades/model' as model does not exist

[ERR 23:59:41.594] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.594] PartCompiler: Cannot compile model

[ERR 23:59:41.595] PartCompiler: Cannot compile part

[LOG 23:59:41.595] PartLoader: Compiling Part 'AJE/Parts/Props/TwinCyclone/TwinCyclone-R2600-23'
[ERR 23:59:41.599] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine/model' as model does not exist

[ERR 23:59:41.599] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.599] PartCompiler: Cannot compile model

[ERR 23:59:41.600] PartCompiler: Cannot compile part

[LOG 23:59:41.600] PartLoader: Compiling Part 'AJE/Parts/Props/TwinCyclone7/TwinCyclone-R2600-7'
[ERR 23:59:41.604] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine/model' as model does not exist

[ERR 23:59:41.604] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.604] PartCompiler: Cannot compile model

[ERR 23:59:41.605] PartCompiler: Cannot compile part

[LOG 23:59:41.605] PartLoader: Compiling Part 'AJE/Parts/Props/TwinWasp94/TwinWasp-R1830-94'
[ERR 23:59:41.608] PartCompiler: Cannot clone model 'Firespitter/Parts/Engine/FS_PropellerEngine/model' as model does not exist

[ERR 23:59:41.608] PartCompiler: Model was not compiled correctly

[ERR 23:59:41.609] PartCompiler: Cannot compile model

[ERR 23:59:41.609] PartCompiler: Cannot compile part

Not familiar enough with FS to know for sure which engines go with which folders in the latest release, perhaps @RoverDude can remember.

Edited by Gaiiden
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Hmm.  @Gaiiden do you have the FIrespitter parts installed?  There is a pre-existing and longstanding issue in AJE where those errors will appear in the log if you don't, because those parts are created from scratch rather than editing the existing Firespitter parts with MM (no real way around that except to convert them).

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5 hours ago, blowfish said:

Hmm.  @Gaiiden do you have the FIrespitter parts installed?  There is a pre-existing and longstanding issue in AJE where those errors will appear in the log if you don't, because those parts are created from scratch rather than editing the existing Firespitter parts with MM (no real way around that except to convert them).

I have the latest firespitter installed - I made mention of the issue because when I checked in the FS directory I didn't see the folders referenced by the config errors

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Still trying to put the pieces together, but it looks like very old stuff we're dealing with here

  • FS_PropellerEngine and FS_PropellerEngineElectric were moved to legacy parts
  • FS_PropellerEngine2blades seems to only have ever existed in a zip file that was removed in the commit above

I'm tempted to remove those parts since no one could have actually been using them for quite some time.  Maybe those models have better equivalents in more modern versions of Firespitter but I really don't have time to hunt down those details right now.

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8 hours ago, theonegalen said:

Any plan to make AJE configs for the Airplane Plus mod? I really like the mod, but it doesn't work so well with FAR.

The ones who understand the propeller configs are @NathanKell and @ferram4, I'm not sure if they plan to work on adding engines at any point

10 minutes ago, the_machemer said:

Does tweakscaling engines mess up the calculations? 

AJE has configs that remove the Tweakscale module from any engines.  Or at least they should.

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Hey guys, quick question, How do I get your stuff to run on Jet-A, since it's all ModuleManager?  Or, can I get your MM to capture my own airbreathers?  Or, could I somehow apply your adjustments internally to my own cfg files?

Thanks.

Edit:  Using the debugger to hand-copy the modules to a blank text file.

Edit 2:  I'm not drunk enough for this...  I've got an -8C5 that wont create positive thrust...  FML...

Edited by Verran
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On 8/3/2016 at 2:53 AM, NathanKell said:

What engines are included in the mod? WWI engines should be fairly trivial to model, engines with supers and variable-pitch props are harder.

There are a few WW1 era props, but mostly WW2 engines. Packard Merlin, DB 605, Griffon, Sakae 21, R-2800 (F4U version), V-1710 (both P-38 and P-41 versions), etc. Very well modeled, nicely stockalike.

EDIT: actually, as I'm looking through the newest release of AJE, a lot of these engines were previously modeled with the Firespitter procedural engines. Perhaps those configs would work with the APP models?

Edited by theonegalen
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So, it looks like as of now, AirplanesPlus would need new configs for the  Hispano-Suiza 8Be (Spad VII), Oberursel Ur.II (Fokker Dr.I), Nakajima Sakae (21 and 12, I assume), and the  Klimov VK-105PF-2 (Yakovlev Yak-3) in order to be compatible with AJE.

Is there any good documentation for building one's own AJE piston engine configs?

Edited by theonegalen
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