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

[Hodo]

I take it there is nothing on the performance of the Pratt & Whitney F-100 engines? They are overheating at pretty low speed mach 2.06 maybe 2.075 when a pair of them can push a real F-15A Eagle over Mach 2.5.

[jrandom]

I take it there is nothing on the performance of the Pratt & Whitney F-100 engines? They are overheating at pretty low speed mach 2.06 maybe 2.075 when a pair of them can push a real F-15A Eagle over Mach 2.5.

You might be flying too low. It's my understanding that at those speeds in the temperature of the air being compressed as it enters the engine that causes this behavior with AJE. Either fly slower, or higher.

At least, that's my understanding of what's going on. I'm not 100% certain that it's correct.

[Hodo]

You might be flying too low. It's my understanding that at those speeds in the temperature of the air being compressed as it enters the engine that causes this behavior with AJE. Either fly slower, or higher.

At least, that's my understanding of what's going on. I'm not 100% certain that it's correct.

In the picture I posted, I was at 10.7km and climbing on RO Earth, so at an altitude of 35kft ASL. Which is a little bit higher then where the F-15A did the Mach 2.5+ run. When I tested again at 18km altitude, the engines overheated at mach 1.25. Which made NO sense to me.

Not explecting that aircraft to reach mach 2.5 but the engines shouldnt be frying due to speed when the real ones go a fair bit faster than that.

EDIT, for those to lazy to go back a page.

[jrandom]

Yep, that's the air heating up as it's compressed into the intake, so I'm guessing the config needs to be tweaked somehow (assuming it's possible to configure that) to better match reality. The higher you fly, the faster you can go before the air overheats upon compression, it's just happening lower than it should, I guess.

[Hodo]

Yep, that's the air heating up as it's compressed into the intake, so I'm guessing the config needs to be tweaked somehow (assuming it's possible to configure that) to better match reality. The higher you fly, the faster you can go before the air overheats upon compression, it's just happening lower than it should, I guess.

That is what I am thinking. It isn't a mod breaking problem it is just throws some designs off a bit.

[camlost]

Yep, that's the air heating up as it's compressed into the intake, so I'm guessing the config needs to be tweaked somehow (assuming it's possible to configure that) to better match reality. The higher you fly, the faster you can go before the air overheats upon compression, it's just happening lower than it should, I guess.

Just increase tcomp, tinlt and tfan a little bit, maybe by 100

[ThorBeorn]

I said I was gonna post the cfg for extra inlets, so here it is. It adds the module to 14 inlets, some of which AndrewATGB has already made a fix for. These include: The circular intake from AJE, all intakes from RftS, Cone intakes from Taverios Pizza and Aerospace and rescales of them in Rfts and the one intake from DaMichels parts, plus an oblong intake from FS. I think that's all. Let me know if you have any thoughts about it.

Link: https://www.dropbox.com/s/3ii9l3j7xijn6ha/Moreinlets.cfg

[NathanKell]

Ah. Um, RftS does include AJEInlet support now. Sorry I was so late with the commit. It's in the repo.

Also, camlost, after banging my head one too many times on YASim's crappy piston engine modeling, I rewrote most all of it, borrowing some from JSBSim but also modeling intercoolers and (to some extent) turbochargers.

https://www.dropbox.com/s/fjawbskq3zurcj5/AJENK.zip

To take advantage, the engine configs need to be changed a bit. Here are the changes I propose.

If you want more engines, you can grab the engines from here:

https://github.com/NathanKell/ReachingfortheStars/tree/master/RftS/Parts/Props

Note that I would request you not add the M82S, BMW801F, Fiat1600, Jumo222, and M85 to AJE as they are fictional RftS-verse engines.

Finally, if you would like to create more engines, you can use the AJEProps page of my Calcs.xls sheet, which contains instructions for matching engine performance.

Edited June 30, 2014 by NathanKell

[camlost]

Ah. Um, RftS does include AJEInlet support now. Sorry I was so late with the commit. It's in the repo.

Also, camlost, after banging my head one too many times on YASim's crappy piston engine modeling, I rewrote most all of it, borrowing some from JSBSim but also modeling intercoolers and (to some extent) turbochargers.

https://www.dropbox.com/s/fjawbskq3zurcj5/AJENK.zip

To take advantage, the engine configs need to be changed a bit. Here are the changes I propose.

If you want more engines, you can grab the engines from here:

https://github.com/NathanKell/ReachingfortheStars/tree/master/RftS/Parts/Props

Note that I would request you not add the M82S, BMW801F, Fiat1600, Jumo222, and M85 to AJE as they are fictional RftS-verse engines.

Finally, if you would like to create more engines, you can use the AJEProps page of my Calcs.xls sheet, which contains instructions for matching engine performance.

There's exhaust thrust, anything else is new?

[Hodo]

Camlost, about the Pratt& Whitney F100, I think I found a minor flaw in its heat range. It is overheating at a bit to low of speed at a decent altitude. I did a dozen tests before the new RO broke my install. I posted the pictures of a few of those tests back in post #553. The F100 is overheating at over 30kft at Mach 2.06 when it is rated to push the F-15A Eagle over Mach 2.5 at the same altitude. My test aircraft is lighter than the F-15A and should match the top speed but the engines are overheating long before it can get there. It isn't a drag related issue, it is a turbine overheat issue. Perhaps the engines are 5-10% to low on the heat scale?

[NathanKell]

camlost: anything else? Uh, the entire way horsepower is calculated for piston engines? Intercooler and ram air modeling? Multiple boost ratings and settable maximum manifold pressure?

[Frederf]

Why don't the stock intakes all have air intake areas?

[Hodo]

Why don't the stock intakes all have air intake areas?

Which ones don't? I haven't looked at all the stock ones yet.

Camlost, any plans on additional jet engines? Perhaps some other modern Russian, Chinese, and European jet engines?

[ThorBeorn]

Maybe some Mig-25/Mig-31 engines? Soloviev D30F6 and Tumansky R-15B.

[Hodo]

Maybe some Mig-25/Mig-31 engines? Soloviev D30F6 and Tumansky R-15B.

The D30 is in game, it is a modified jet engine from the B9 pack. One of my designes use it for a while, but I dropped it because it is MASSIVE.

[Frederf]

Which ones don't? I haven't looked at all the stock ones yet.

Camlost, any plans on additional jet engines? Perhaps some other modern Russian, Chinese, and European jet engines?

Engine nacelle for one.

[ZobrAA]

I have an issue.

Game stucks loading Squad/Parts/Engine/rapierEngine/part/RAPIER, deleting @PART[RAPIER]:Final {} from AJL.cfg solves the problem... What can be wrong?

Also I didn't notice AirIntake definition on Rapier AirBreathing module...

Edited July 6, 2014 by ZobrAA

[Hodo]

Engine nacelle for one.

Heh, I hadn't used that on anything yet. Good to know.

[NathanKell]

ZobrAA: Please install AJE cleanly (don't modify anything; nuke and reinstall if you did) and then run KSP until it hangs. Force quit it. Then:

Upload your output log (NOT ksp.log) to dropbox or something.

Windows: KSP_win\KSP_Data\output_log.txt

Mac OSX: Open Console, on the left side of the window there is a menu that says 'files'. Scroll down the list and find the Unity drop down, under Unity there will be Player.log Aka Files>~/Library/Logs>Unity>Player.log

Linux: ~/.config/unity3d/Squad/Kerbal\ Space\ Program/Player.log

==========

In other news I've put up my prop changes, my suggested cfg changes, and my beginning rework of AJESolver so variables have clearer names, to github. I need to go through the intakes and give them correct areas: for now I simply did a hack of 2x area. This is because acore (and thus intake area) is in square feet, but the values supplied in the original AJE cfg seem to be half the square footage they should be.

[Hodo]

==========

In other news I've put up my prop changes, my suggested cfg changes, and my beginning rework of AJESolver so variables have clearer names, to github. I need to go through the intakes and give them correct areas: for now I simply did a hack of 2x area. This is because acore (and thus intake area) is in square feet, but the values supplied in the original AJE cfg seem to be half the square footage they should be.

Where is this cfg change, is it in the OP or in the RO OP?

And how does it affect things over now?

[NathanKell]

I linked to the github repo in my post above yours. If you go there and click Download Zip, you can just nuke your old AJE folder and replace it with the AJE folder in the archive.

Note that it's compiled against the latest dev release of FAR, too. If you find things not working as expected, download the FAR repo and merge the GameData folder with your own to update your FAR.

Changes:

*Remove the IntakeAir resource from parts when AJE removes the ResourceIntake (this saves considerable mass--15 units of intake air is nothing to sneeze at for tiny prop planes!)

*Jets now report their gross as well as net thrust on right-click.

*Enforce engine response time when afterburner is requested but the engine is not yet at 66.7% throttle (AB threshold). As things were in 1.4, you could start the engine in full AB and it would instantly spool up, because once the *requested* throttle (not the actual throttle) is in the AB range, AJE disabled engine response time. Now it's smarter.

*Source improvements: in AJESolver rename some variables for legibility and remove some code that was only there for the webapp and useless to AJE

*Give intakes a flat 2x multiplier to area, until I go and actually set the areas appropriately. The existing AJE settings didn't make a lot of sense, since area should be the square footage of the intake opening, and intakes of different shape and size were sharing the same value.

It also includes a pretty much completely rewritten Piston Engine class, using some code from JSBSim (the other flight dynamics model that FlightGear uses; it also uses YASim, which AJE originally used for piston engine and prop modeling), as well as a good bit of original code from me to try to model boost pressure, intercoolers/aftercoolers, turbochargers, auto-switching of superchargers/turbochargers, and other fun things.

Example module:

MODULE
{
	name=AJEPropeller
	IspMultiplier = 1
	useOxygen = true
	r0 = 1.4859 // propeller radius, in meters
	v0 = 352 // reference velocity, in knots
	omega0 = 1867 // reference propeller RPM
	rho0 = 0.69 // reference air density, in kg/m^3
	power0 = 1440 // reference BHP
	fine = 0.2 // min multiplier to advance ratio
	coarse = 5 // max multiplier to advance ratio

	exhaustThrust = 0.0 // multiplier to exhaust thrust (carefully designed radiators and engine exhaust could provide thrust rather than drag; c.f. P-51, which has a normalized exhaustThrust of 1.0)

	displacement = 1829.4 // engine displacement in cubic inches
	compression = 6.7 // engine compression ratio
	omega = 1800 // 2700 RPM for the engine. Maximum propeller RPM (maximum engine RPM * gearratio)
	power = 1350 // BHP at maximum takeoff power (no ram air)
	gearratio = 0.666666666666667 // engine->propeller reduction gear ratio
	BSFC = 8.786E-8 // brake specific fuel consumption, in kg/kW-s. Conversion factor from lb/hp-hr = 1.68968E-07
	coolerEffic = 0.5 // efficiency of the cooler. Used as interpolation factor between ambient temperature and uncooled charge air temperature, with a minimum temperature in C of coolerMin
	coolerMin = 0 // minimum temperature for the charge air, in C
	ramAir = 0.4 // a multiplier to the effectiveness of using ram air to increase charge pressure. 0 means use ambient pressure absent any dynamic pressure increase; 1.0 means use the dynamic pressure rather than the ambient pressure as the pressure for the super/turbocharger intake.
	boost0 = 52 // rated boost 1 (maximum manifold pressure to be maintained), in inches of mercury
	rated0 = 3000 // rated altitude for boost 0, in meters. STATIC. Not ram air.
	boost1 = 52 // rated boost 1 (maximum manifold pressure to be maintained), in inches of mercury
	rated1 = 5000 // rated altitude for boost 1, in meters. STATIC. Not ram air.
	cost1 = 54.5 // the cost (in HP) of the boost 1 (i.e. high blower)
	switchAlt = 3600 // the altitude to switch from low blower (boost 0) to high blower (boost 1). Note that this is interpreted ingame as a pressure altitude, taking ram air multiplier into account. So if you're rated for 3km static for boost 0, you might well not switch to boost 1 until 5km if your speed (and thus ram air pressure) is high enough
	wastegateMP = 52 // maximum manifold pressure, in inches of mercury. Any charge pressure beyond this will be vented by the wastegate.
}

It *should* be backwards compatible with prior definitions of piston engines, assuming reasonable default values.

Edited July 9, 2014 by NathanKell

[ZobrAA]

ZobrAA: Please install AJE cleanly (don't modify anything; nuke and reinstall if you did) and then run KSP until it hangs. Force quit it. Then:

Oh

I've actually already fixed the problem by changing "Kerosene" and "LiquidOxygen" to "LiquidFuel" and "Oxidizer"... But anyway thanks for the great mod!

[Hodo]

Thanks Nathan for that.

And Camlost, I made some minor modernization changes to the P&W F100. Mainly because I found the answer to my question earlier on why the F100 was overheating at mach 2.05 instead of mach 2.5. The inlet temp was set for 1800, when the actual F100-229, has a max (released) temp of 2460. This is according to this source.

http://books.google.com/books?id=7SmeqapJ3tIC&pg=PA64&lpg=PA64&dq=F100+PW+inlet+temperature&source=bl&ots=c5lFithhjU&sig=-EtYWmJFZbXdXq3Xla6mrhVDXZE&hl=en&sa=X&ei=s1HoTtbTC8agiQLuufCfAg&ved=0CFQQ6AEwBg#v=onepage&q=F100%20PW%20inlet%20temperature&f=false

[NathanKell]

ZobrAA: cool. Although it's not my mod, it's camlost's!

Hodo: I'll make the AJE one the -229A, which seems the most recent, efficient, and powerful.

Here's a great reference btw: http://books.google.com/books?id=_5vA_5XK33sC&pg=PA584&lpg=PA584&dq=%22j57-p-20%22&source=bl&ots=oPRpSbDVr7&sig=-o3UmLH74DP1SwJ4O5eORtJ1Bfc&hl=en&sa=X&ei=wQ69U8_zF9DgsASgyYCACw&ved=0CDQQ6AEwAg#v=snippet&q=f100&f=false

[ZobrAA]

@NathanKell: Woops! Please forgive me my silliness ^_^" But you sir are also a great modder!

And I'm looking forward for AJE update anyway \_(^-^)_/