[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[Hodo]

Technically those are all turbofans, not turbojets, but then again, not even the TurboJet itself knows what it is.

Anyhow most of those engines explode into melty bits past about 7-800m/sec or so... The "TurboJet" is still spooling over nicely at 1600...

From the realism angle, none of the jets mounting those engines are capable of reaching space, let alone Mach 3.5. The Mig-31, with two D30s only goes Mach 2.83 at extreme altitudes, and 1.2 on the deck...

http://alpha.renegrade.net/NEAR/images/FAR-Kerbals-in-SPAAACE-thumb.jpg

That's a 100x100-or-so orbit with 1500dv left over (clicky for big version). I am not some ace pilot, nor an ace designer, and that's entirely stock.

Ferram, what if we changed the curve so that it starts off with a lot of static thrust for the TJ as well as the basic, but then falls off?

IE:

150kn base

0 speed - 100% (1.0)

400 speed - 50%

1700 speed - 0%

That's probably not very realistic in terms of engine performance from what I understand, but is it possible that would approximate the FLYING performance that FAR is trying to reach?

The thing is, if you want more realistic jet engine performance, download AJE by Camlost. It should not come in FAR as that is an additional item that really has nothing to do with what FAR does.

I use AJE on one of my installs and I love it for its realistic jet engines. But I also like the stock KSP jet engines for their overpowered nature in the basic KSP sized universe. If I wanted realistic jet performance in my stock sized KSP, I would use AJE or KIDS, but seeing as I have a full Realism Overhaul install on here also I do not want an additional realism overhaul light install from my FAR.

[sralica]

I have a problem with CoL shifted to the side. Explained in this thread.

I would appreciate your help.

[Themistocles]

Just wanted to do a quick shoutout to Ferram, for keeping this mod updated at lightning-speed! I honestly couldn't enjoy KSP without FAR. So thanks again for this incredible mod, and all your hard work maintaining it!!

[Gwincraft]

I very much agree with Hodo on this. FAR is a mod focused on making Aerodynamics realistic in KSP. AJE is a mod focused on making Jet Engines perform realistically in KSP. I have multiple installs so that I can play in multiple ways. While I understand that this change is probably due to Ferram being tired of people complaining that their spaceplanes rapidly disassemble at 5k altitude flying Mach 2.5, I feel that the proper response is to educate people, rather than play with values on air breathing engines.

Regardless, FAR is too good to not have. I'll just edit configs if the popular vote is to keep nerfed jets.

Edited July 25, 2014 by Gwincraft

[Wedgenet]

RAPIERS have a max thrust of 60kN now, but I never see more than 40kN on the runway.

Can someone please explain the curve to me? Is there anything I can do design wise to compensate for this?

[Hodo]

RAPIERS have a max thrust of 60kN now, but I never see more than 40kN on the runway.

Can someone please explain the curve to me? Is there anything I can do design wise to compensate for this?

Covered a few pages ago.

[Grunf911]

Hi @Renegade, @ferram4,

As promised here is the test gallery with recorded speeds at the end of the runway (more less)

Jet Engines Test

Edited July 25, 2014 by Grunf911

[Renegrade]

But I also like the stock KSP jet engines for their overpowered nature in the basic KSP sized universe.

Ah, in that case, edit away (note that the stock engines also have their own overrides in the file as well, specific to each engine, may want to edit those too).

The thing is, if you want more realistic jet engine performance, download AJE by Camlost. It should not come in FAR as that is an additional item that really has nothing to do with what FAR does.

AJE looks fairly computationally complex internally (I dearly hope none of those iterative methods are being called in real time). It's on my "to check out" list but I'm a bit worried about the impact it would have on framerate.

I'd be perfectly satisfied with a simplified version of AJE, which is pretty much what Nathan suggested during the initial concerns about infinijets crashing into the Mun came to light.

I very much agree with Hodo on this. FAR is a mod focused on making Aerodynamics realistic in KSP. AJE is a mod focused on making Jet Engines perform realistically in KSP. I have multiple installs so that I can play in multiple ways. While I understand that this change is probably due to Ferram being tired of people complaining that their spaceplanes rapidly disassemble at 5k altitude flying Mach 2.5, I feel that the proper response is to educate people, rather than play with values on air breathing engines.

Actually if you read this whole thread, a common theme is Ferram finding the stock jets to be massively silly in terms of overpoweredness. This isn't any new thing. Just recent changes have brought it to a head.

The real issue here is that changes to FAR in recent editions have resulted in massive speedups over previous (0.23.5/0.13.x) versions, as drag has fallen quite a bit. The same design that went Mach 1.4 at sea level (which is plenty of speed to tear it apart with any sort of un-gentle control input) now goes about 2.5-2.6. (sea level being 'around 300m altitude' as it's a bit hard to test at zero)

And for the record, I was more about having the drag fixed than engines. Apparently the new drag is more correct though.

NB: Previous versions of FAR already had jet engine correction in them, this isn't new either. 0.12 (the earliest version I could find lying around in my system) already has jet engine mods.

Reference: in stock aero, the same test plane goes around 239m/sec at "sea level", and about 341 at 4km, so older versions of FAR already have the same affect on planes as it does on rockets.

Just wanted to do a quick shoutout to Ferram, for keeping this mod updated at lightning-speed! I honestly couldn't enjoy KSP without FAR. So thanks again for this incredible mod, and all your hard work maintaining it!!

He definitely is the bomb. I just hope he understands we all get excited about things because FAR is fascinating and worth discussing, not because we dislike it or something.

[Wedgenet]

Covered a few pages ago.

Having reread the last few pages a couple times, I didn't find it, sorry.

Could you throw me a bone and at least give me the page it's on?

[Hodo]

Ah, in that case, edit away (note that the stock engines also have their own overrides in the file as well, specific to each engine, may want to edit those too).

AJE looks fairly computationally complex internally (I dearly hope none of those iterative methods are being called in real time). It's on my "to check out" list but I'm a bit worried about the impact it would have on framerate.

I'd be perfectly satisfied with a simplified version of AJE, which is pretty much what Nathan suggested during the initial concerns about infinijets crashing into the Mun came to light.

Actually if you read this whole thread, a common theme is Ferram finding the stock jets to be massively silly in terms of overpoweredness. This isn't any new thing. Just recent changes have brought it to a head.

The real issue here is that changes to FAR in recent editions have resulted in massive speedups over previous (0.23.5/0.13.x) versions, as drag has fallen quite a bit. The same design that went Mach 1.4 at sea level (which is plenty of speed to tear it apart with any sort of un-gentle control input) now goes about 2.5-2.6. (sea level being 'around 300m altitude' as it's a bit hard to test at zero)

Lets take this aircraft that I use in Realism Overhaul with AJE and FAR 13.3 as an example of how a real jet engine works.

Note it has a TWR of .9:1 which is about where most 4th Generation fighters sit.

It is powered by a Pratt & Whitney F100-229 which generates 129kn of thrust in afterburner at sea level.

It peaks a bit higher than that.

This craft at less than 2.5km (or 7kft) real alt tops out at Mach 1.05.

The engine peaks at 150.2kn of thrust.

The issue isn't power or drag, it is the scale. Which is not something FAR should mess with. FAR is Ferram Aerospace Research, or an AERODYNAMIC FIX FOR THE STOCK KSP ATMOSPHERE. Not Ferram Aerospace Research and Jet Engine Simulator.

[Hodo]

Having reread the last few pages a couple times, I didn't find it, sorry.

Could you throw me a bone and at least give me the page it's on?

Read the last few pages, it's been non-stop people complaining they were OP!!!!111one and Renegade having some suggestions.

And then ferram4 says in the changelog: I'm going with Renegade's numbers, blame her/him if you don't like it.

123546780char

[Wedgenet]

123546780char

My question was about the difference between the thrust in the part.cfg and what I observed in-game, not a question of why this was done. I'll let you get back to arguing with Renegrade about real jet engines. Thanks, bud.

[Renegrade]

As promised here is the test gallery with recorded speeds at the end of the runway (more less)

Ouch, 22 tons, heavy duty plane! It looks a lot lighter than it is.

I'd recommend either doubling the number of rapiers, or going the 'edit config files' route.

In FerramAerospaceResearch.cfg,

- stock engine thrust figures are on line 249, 264, and 140 for TurboJet, RAPIER, and Basic engines respectively (looks like "@maxThrust = 60")

- The entire part between 238 and 244 can be deleted.

Having reread the last few pages a couple times, I didn't find it, sorry.

Could you throw me a bone and at least give me the page it's on?

The curve for rapiers is:

			@key,0 = 0 0.7 0 -0.00098
			@key,1 = 170 0.63 0 0
			@key,2 = 400 0.7 0.00049 0.00049
			@key,3 = 1100 1 0 0
			key = 1700 0 -0.00098 0

(note that this uses cubic interpolation and is customized with some tangents so all numbers should be considered 'approximate')

The first two columns after the equal sign are the critical bits. "0 0.7" in the first line means that at 0m/sec, the engine develops 70% of thrust. The second line means that at 170 m/sec, it develops 63%, and so forth.

There's two ways of getting to or past 1100 - less drag, or moar engines. Less drag could be flying higher, or a sleeker airplane.

[Hodo]

My question was about the difference between the thrust in the part.cfg and what I observed in-game, not a question of why this was done. I'll let you get back to arguing with Renegrade about real jet engines. Thanks, bud.

Ah I misread what you were asking then, my fault.

[monstah]

I love this mod, but then I found NEAR and I love it even more. IMO, it should be linked to in the original post.

[camlost]

AJE looks fairly computationally complex internally

How do you reach this conclusion if you haven't tried it? It's not computationally expensive at all

[Renegrade]

(I missed this post somehow)

The issue isn't power or drag, it is the scale. Which is not something FAR should mess with. FAR is Ferram Aerospace Research, or an AERODYNAMIC FIX FOR THE STOCK KSP ATMOSPHERE. Not Ferram Aerospace Research and Jet Engine Simulator.

What do you mean by scale? The difference in pressure? 0.813 atm exists on stock Kerbin at about 1202m. n 14.1, I'm getting Mach 1.030 with the nerfed RAPIER engine on my orbital version of the Rapier test plane at 0.813 atmospheres of pressure. 59.172kpa, 0.025 Cd, 29.1m^2 reference area. 40.5kn / 0.7 TWR. (it went all the way around the world prior to that test, landed, took off, and performed that test, and still has like half fuel.. )

Anyhow, don't yell at me about engine changes existing in FAR, those predate me! They're just a bit more strict now, that's all.

EDIT: FYI, 0.24.2 is out, and addresses some UI issues. May help with the problem we've been collectively having.

How do you reach this conclusion if you haven't tried it? It's not computationally expensive at all

Well, I know you based it off of NASA models, and just about anything NASA is computationally expensive..

Kidding aside though, I peeked through the source as I was curious about how much it did, and I was a bit shocked (also impressed though!) by the level of simulation you're doing. It looked rather expensive to me. I didn't whip out the old profiler or anything so I could be mistaken.

Given that assurance though, I'd really like to try it out.. is it 0.24 friendly?

[Grunf911]

Ouch, 22 tons, heavy duty plane! It looks a lot lighter than it is.

I'd recommend either doubling the number of rapiers, or going the 'edit config files' route.

In FerramAerospaceResearch.cfg,

- stock engine thrust figures are on line 249, 264, and 140 for TurboJet, RAPIER, and Basic engines respectively (looks like "@maxThrust = 60")

- The entire part between 238 and 244 can be deleted.

..

I am afraid i will need to go the editing route, since the purpose of this plane (SSTO) was to get up to LKO and deploy satelites, and service the LKO space station i plan to build. With funds in the play, having a SSTO is vital.

Now, if i added 1 more rapier, I would essentially double the consumption, and therefore no longer be able to reach LKO with my ssto, so I would need more fuel... It's a vicious cycle.

Also i thought slimming it down, but if you think about it, it has ONLY 1 liquid fuel tank and only 1 liquid fuel / oxidizer tank for LKO, which i think is the bare minimum. Add to that 1x TAC life module, 1x battery, minimum monoprop for manuvering, and 4x intakes, and that is what i have essentially built. I am not sure if i can get it much lighter, and still have some payload. I did instruct Bob and Mating Kerman to take a pee before takeoff

I have every confidence that you and ferram will find the correct balance, just please note 1 thing. Unlike turbojets, and basic jets, RAPIER was meant to go to space. So if you nerf the thrust, please DO* increase fuel efficiency, so that I could in fact put 2 of them and get to at least LKO. I like that flying planes is easy, and getting to orbit is challenging.

Keep up the good work

Edited July 25, 2014 by Grunf911

[Hodo]

(I missed this post somehow)

What do you mean by scale? The difference in pressure? 0.813 atm exists on stock Kerbin at about 1202m. n 14.1, I'm getting Mach 1.030 with the nerfed RAPIER engine on my orbital version of the Rapier test plane at 0.813 atmospheres of pressure. 59.172kpa, 0.025 Cd, 29.1m^2 reference area. 40.5kn / 0.7 TWR. (it went all the way around the world prior to that test, landed, took off, and performed that test, and still has like half fuel.. )

Anyhow, don't yell at me about engine changes existing in FAR, those predate me! They're just a bit more strict now, that's all.

I wasn't yelling just highlighting a point.

And scale, Kerbin is roughly 1/3rd of the of Earth in every way.

Kerbin Atmosphere 69.1km deep.

Earth Atmosphere 180km deep.

When I fly something in RSS/RO at 1.2km with AJE, and that same engine is out performing the FAR nerfed engine, there is a problem with the nerf.

Just to sum it up, because you are admirably sticking to your guns, FAR should not be modifying jet engines to make them more realistic when there is already a mod that does all that and does it extremely well.

And 22 tons is not that heavy when talking about aircraft.

F-15C Eagle is 20 tons on take off with just fuel, and over 30 tons fully loaded.

Su-27 Flanker 23 tons on take off, and over 30 tons fully loaded.

F-16 Fighting Falcon AKA Viper 12 tons on take off, and nearly 20 tons fully loaded.

F-105 Thunderchief AKA Thud, 16 tons on take off, and nearly 24 tons fully loaded.

Edited July 25, 2014 by Hodo

[ferram4]

Version 0.14.1.1 is up with 0.24.2 compatibility, some attempts and bugfixing the UI, and some tweaks to the airbreathing nerf. In particular,y htey should make quite a bit more thrust static and on the runway, and only a little bit more in high-velocity flight.

@Grunf911: You know that fuel consumption does not work that way, since it's measured relative to thrust, right? Cutting the thrust of the engine in half results in it burning half the fuel, not making half the thrust for the same amount of fuel. Your only losses to efficiency would have been needing to carry more engines.

@Hodo: Yes, FAR shouldn't have to tweak jet engines.

But. Lots of users throw on FAR and don't include AJE. I'm also quite tired of going on reddit and seeing the "LOL FAR MAKZ DA PLANZ GO FASTA" kinda stuff. It doesn't affect AJE users, and it fixes something that was obviously balanced only against stock drag, so I think it's acceptable and (just barely) within scope.

[Wedgenet]

The curve for rapiers is:

I get it now, thank you. I'm torn between loving and hating the breathing engine changes in FAR 0.14.1. I don't want to remove the nerf entirely since the stock thrust is pretty absurd, so I might just play with the curve to find a flavor I like.

Thanks for the explanation.

Edit: or, why don't I just use AJE in my non RSS/RO game?.. derp.

p.s. Ferram, I want to have your Kerbal babies.

Edited July 25, 2014 by Wedgenet
derp

[Hodo]

So .5 nerf on them. That maybe more inline with the AJE engine performance levels.

Time to test.

Test complete.

Sp-1 used in test, single SABRE-S engine, time to orbit 24minutes. Unmodified engine time to orbit 8minutes. TWR .4 (modified).

I think .5 is pretty close to where it should be, maybe .55 but that maybe pushing it. The craft I used is only 27tons.

Edited July 25, 2014 by Hodo

[Renegrade]

Version 0.14.1.1 is up with 0.24.2 compatibility, some attempts and bugfixing the UI, and some tweaks to the airbreathing nerf. In particular,y htey should make quite a bit more thrust static and on the runway, and only a little bit more in high-velocity flight.

Damn, I've barely just installed 0.24.2 and already we have a brand new FAR! Thanks, Ferram!

You're an updating beast

@Grunf911: You know that fuel consumption does not work that way, since it's measured relative to thrust, right? Cutting the thrust of the engine in half results in it burning half the fuel, not making half the thrust for the same amount of fuel. Your only losses to efficiency would have been needing to carry more engines.

And mass, in FAR, is significantly less opportunity cost than it is in stock, thank goodness.

Just to sum it up, because you are admirably sticking to your guns, FAR should not be modifying jet engines to make them more realistic when there is already a mod that does all that and does it extremely well.

Well, ideally the stock engines wouldn't be quite so crazy... and then it wouldn't even be a problem at all. I have to say that I understand your viewpoint and that it does have merits. However, let me just say one more thing on the topic: At least the way Ferram has done the changes is very user-friendly. Not too hard to edit a ModuleManager file

Thanks for the explanation.

No problem. That curve system is similar to ones I've implemented myself.

So .5 nerf on them. That maybe more inline with the AJE engine performance levels.

Time to test.

I'ma testin' too!

Initial Results: The delta-wing turbo goes about mach 1.65 down at 300m (0.93+ atmospheres). It's not entering orbit on air breathers alone. UI seems much improved.

That's a bit faster than 0.13.x FAR, but only a bit. (it's quite a bit faster than stock, but stock atmosphere is as I said, a strange sort of transparent liquid lead)

The rapier goes about mach 1.22-ish in the same conditions. That seems good.

I haven't seen that "two sets of stats" stuff since, nor any problems. The only outstanding issue is that the FAR UI doesn't go away when the stock HUD is turned off (F2)

Edited July 26, 2014 by Renegrade

[Themistocles]

Version 0.14.1.1 is up with 0.24.2 compatibility, some attempts and bugfixing the UI, and some tweaks to the airbreathing nerf. In particular,y htey should make quite a bit more thrust static and on the runway, and only a little bit more in high-velocity

Thanks for updating so quickly!

[Gwincraft]

I'm pretty sure ferram is actually like... a team of people with how fast he responds to people/patches this project. Thank you!