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

[NathanKell]

Looks like the SABRE tops out about Mach 4.9; it has a final CPR (prat3) of 3, not 1, which means it will top out in terms of thrust under Mach 5.

[blowfish]

1. The thrust always depends on speed and altitude at the same time. They all 'lose' thrust when you climb up. I don't think the SABRE loses thrust over M2 in level flight

2. By default the engines have a 3% idle thrust

1) I was using a pretty shallow ascent profile. I know that these effects are somewhat normal but I was seeing a >50% drop in thrust even before I climbed out of the lower atmosphere.

2) Noted.

[blowfish]

Okay, you were right camlost . I tried a new ascent profile where I stayed just below the high dynamic pressure zone most of the time and had no trouble reaching mach 5. One of the fastest ascents I've ever done too. I didn't realize that altitude affected the engines so sharply.

Unrelatedly, some of the engines seem to be producing no thrust even after a reinstall (I've tested the JT8D, PW100, and CF6). Do I have something installed incorrectly?

[Hyomoto]

I'm having an issue which I'm not sure there is a solution for. Using Fine Print, there are some contracts you can take that have you observe way points around Kerbin. However, I've gotten a few now that need me to fly at altitudes of > 15km. However, no matter which stock variant engine I use, I cannot seem to find any that will let me fly that high. 15km seems to pretty much be the ceiling for all engines and intakes. Any advice?

[SSR Kermit]

I just wanted to leave some props for this mod.

It makes jets a lot more interesting in my opinion. Although in my case, it made spaceplanes even easier since I was already designing for semi-realistic jets-- without AJE they didn't have the right characteristics at the altitudes I designed for and would run into all kinds of problems (notably not using fuel quick enough!), especially on parts attempting to 'fix' that through fine-tuning the performance curves....

Also a question for the knowledgeable sorts:

I've managed to do some very efficient ascent profiles by quickly climbing to altitude (10km) and then doing a high-mach (as high as the engine can go) dive through the atmosphere (a sort of S-curve). I then ignite the rockets at about 20-30km (depending on the jet engine in use). I've come to call it "the fire dolphin", but I'm wondering if it already has a name. I am using DR untweaked and just stayed inside the thermal envelope. Also real fuels. It's critical that the mass of the vessel decreases smoothly, or the final ascent will flatten out inside the atmosphere. Should that still be considered OP in terms of the engines, or is that sort of semi-realistic at least in the KSP sense?

Edited October 29, 2014 by SSR Kermit
accuracy (fire!)

[blowfish]

I'm having an issue which I'm not sure there is a solution for. Using Fine Print, there are some contracts you can take that have you observe way points around Kerbin. However, I've gotten a few now that need me to fly at altitudes of > 15km. However, no matter which stock variant engine I use, I cannot seem to find any that will let me fly that high. 15km seems to pretty much be the ceiling for all engines and intakes. Any advice?

Maybe add a rocket engine for high-altitude maneuvers?

[launchpad_liftoff]

Excuse me for not checking ~90 pages of posts because the search feature sucks, but does this mod properly work with NEAR?

[NathanKell]

launchpad_liftoff: yes. I have no idea why it wouldn't; it doesn't add wings...

SSR Kermit: I don't know of a name for that, but that is what Skylon plans to do, and it was how the F-104 got up to speed most quickly and efficiently, so there's precedent.

[camlost]

Okay, you were right camlost . I tried a new ascent profile where I stayed just below the high dynamic pressure zone most of the time and had no trouble reaching mach 5. One of the fastest ascents I've ever done too. I didn't realize that altitude affected the engines so sharply.

Unrelatedly, some of the engines seem to be producing no thrust even after a reinstall (I've tested the JT8D, PW100, and CF6). Do I have something installed incorrectly?

Find the dev version on github

I'm having an issue which I'm not sure there is a solution for. Using Fine Print, there are some contracts you can take that have you observe way points around Kerbin. However, I've gotten a few now that need me to fly at altitudes of > 15km. However, no matter which stock variant engine I use, I cannot seem to find any that will let me fly that high. 15km seems to pretty much be the ceiling for all engines and intakes. Any advice?

There's no hardcap, just as the air is thin at 15km, which corresponds to ~24km on earth, all engines are weak. But with a reasonable design and choice of engine, it's still possible

I just wanted to leave some props for this mod.

It makes jets a lot more interesting in my opinion. Although in my case, it made spaceplanes even easier since I was already designing for semi-realistic jets-- without AJE they didn't have the right characteristics at the altitudes I designed for and would run into all kinds of problems (notably not using fuel quick enough!), especially on parts attempting to 'fix' that through fine-tuning the performance curves....

Also a question for the knowledgeable sorts:

I've managed to do some very efficient ascent profiles by quickly climbing to altitude (10km) and then doing a high-mach (as high as the engine can go) dive through the atmosphere (a sort of S-curve). I then ignite the rockets at about 20-30km (depending on the jet engine in use). I've come to call it "the fire dolphin", but I'm wondering if it already has a name. I am using DR untweaked and just stayed inside the thermal envelope. Also real fuels. It's critical that the mass of the vessel decreases smoothly, or the final ascent will flatten out inside the atmosphere. Should that still be considered OP in terms of the engines, or is that sort of semi-realistic at least in the KSP sense?

Diving is realistic actually. While in stock, you are rewarded for climbing up fast and level out at 20km or sth, which is not realistic. So AJE is always harder that stock.

[Hyomoto]

I've been able to get up that high, even maintain for short periods, and honestly the only way I see it working is to do a ballistic trajectory. At about 10km you can usually hit your highest mach, and a sharp, sudden climb at full afterburner might just allow me to punch up to 20km before I start falling again. That may suffice to complete a node on the contract, and who knows, maybe it's even a bit fun considering it actually IS a design and method challenge. However, I was sort of hoping that you wouldn't just tell me that reasonable design and engine choice can make it possible, but give me some pointers as to what kind of engine and intake choice may make it possible.

[camlost]

I've been able to get up that high, even maintain for short periods, and honestly the only way I see it working is to do a ballistic trajectory. At about 10km you can usually hit your highest mach, and a sharp, sudden climb at full afterburner might just allow me to punch up to 20km before I start falling again. That may suffice to complete a node on the contract, and who knows, maybe it's even a bit fun considering it actually IS a design and method challenge. However, I was sort of hoping that you wouldn't just tell me that reasonable design and engine choice can make it possible, but give me some pointers as to what kind of engine and intake choice may make it possible.

20km/0.7=28km on Earth. The only airplane flies that high I can think of is the Blackbird, which uses 2xJ58. There are some pictures of a Blackbird replica I made in this thread

[jrandom]

I've been able to get up that high, even maintain for short periods, and honestly the only way I see it working is to do a ballistic trajectory. At about 10km you can usually hit your highest mach, and a sharp, sudden climb at full afterburner might just allow me to punch up to 20km before I start falling again. That may suffice to complete a node on the contract, and who knows, maybe it's even a bit fun considering it actually IS a design and method challenge. However, I was sort of hoping that you wouldn't just tell me that reasonable design and engine choice can make it possible, but give me some pointers as to what kind of engine and intake choice may make it possible.

Fun thing about jets is that to go faster, first you have to go faster. Get to some decent altitude where you can still accelerate when flattened out. As you go faster, you'll find your acceleration increasing. Pitch up a tiny bit and keep climbing upwards w/out letting your velocity drop any. This should get you up to high altitudes at high speeds w/out having to go full afterburner.

[Hyomoto]

@camlot - I just remembered, are there any plans to officially fix the B9 engines? The particular part you suggested is the one I used to show off the CoM being WAAAAAAAAAAAAAAAY out of whack. You said it was a simple fix but there haven't been any updates to AJE. I found the fix was pretty simple: delete the parts. There are still desirable alternatives though.

[camlost]

@camlot - I just remembered, are there any plans to officially fix the B9 engines? The particular part you suggested is the one I used to show off the CoM being WAAAAAAAAAAAAAAAY out of whack. You said it was a simple fix but there haven't been any updates to AJE. I found the fix was pretty simple: delete the parts. There are still desirable alternatives though.

I checked there's only one engine, J57 has CoM setted wrong, all others are normal

[dreadicon]

Just wanted to drop back in and inquire briefly if Hypersonic engines are being considered, and to give a big motion of support for utilizing engines from more mods, such as Retro Future and BahamutoD's pack. The two shortfallings I have encountered so far functionally are the lack of propfans and SCRAM jet engines, despite real world statistics being available for both. And graphically, the mod could really use some variety....

[jrandom]

Just wanted to drop back in and inquire briefly if Hypersonic engines are being considered, and to give a big motion of support for utilizing engines from more mods, such as Retro Future and BahamutoD's pack. The two shortfallings I have encountered so far functionally are the lack of propfans and SCRAM jet engines, despite real world statistics being available for both. And graphically, the mod could really use some variety....

I second this notion. Right now, all we've got are some ramjets from TVPP. SCRAMJETs would be awesome to play around with.

[Guest]

I've posted a few propositions for RF engines about two pages back.

Also, I've got a proposition to further improve realism. I'd like to add engine bodies to each engine, in form of a fuselage from it's mod of origin, or a stock one should that be unavailable. It'd help to properly simulate different engine sizes and lengths. Some engines could be available in "dual" configuration (two of them on a bicoupler) if they're often found on dual-engine fighters. It'd both add realism and make for an interesting design challenge.

[camlost]

@dreadicon, the code from NASA simulates turbojets, turbofan and ramjets. There's no way to make a SCRAMJET, besides I don't think there is data of a SCRAMJET. So someone needs to show me the data, then I can think of incorporating BJE into AJE and make it.

Same thing goes for propfans and turboprops.

Besides, what is the BahamotoD's pack?

@Dragon01, no. That would break aerodynamics, besides I don't see anything of that sort no covered by TweakScale already.

[Guest]

@Dragon01, no. That would break aerodynamics, besides I don't see anything of that sort no covered by TweakScale already.

Break aerodynamics? I'm not sure what you're talking about. RetroFuture adds an engine which doesn't only consist of the nozzle, and it seems to work fine. What I'm proposing is to make the rest of the engines that way via MODEL nodes. And how would TweakScale help with that anyway? It does exactly nothing remotely relevant to my proposition.

Right now, I'm designing my planes with a structural fuselage (or a bicoupler) in front of each jet engine, because the compressor, burner and turbine all need to go somewhere. What I'm proposing would be essentially making this mandatory, and scaling the fuselage to actually match the size of a real engine.

Edited October 31, 2014 by Guest

[FreeThinker]

Help, my FireSpitter Folding Electric Propellers does not function! It Sais FSCoolant Deprived!

Yet according to the same window it sais it has 5.00 FSCoolant. They functioned fine before I installed AJE and have more than enough electric power. I installed the latest version of FAR and Module Manager. What could be wrong?

Edited November 1, 2014 by FreeThinker

[camlost]

Break aerodynamics? I'm not sure what you're talking about. RetroFuture adds an engine which doesn't only consist of the nozzle, and it seems to work fine. What I'm proposing is to make the rest of the engines that way via MODEL nodes. And how would TweakScale help with that anyway? It does exactly nothing remotely relevant to my proposition.

Right now, I'm designing my planes with a structural fuselage (or a bicoupler) in front of each jet engine, because the compressor, burner and turbine all need to go somewhere. What I'm proposing would be essentially making this mandatory, and scaling the fuselage to actually match the size of a real engine.

If every single engine use that, then you cannot use other aero parts to pretend the engine body is buried in the fuselage. If you force the engine fuselage to bury, then extra drag will occur, get it?

Help, my FireSpitter Folding Electric Propellers no longer function. It Sais FSCoolant Deprived!

Yet according to the same window it sais it has 5.00 FSCoolant. They functioned fine before I installed AJE and have more than enough electric power. I installed the latest version of FAR and Module Manager. What could be wrong?

Recent FS updates changes some propellers to another engine module that is not supported by AJE

[dreadicon]

@dreadicon, the code from NASA simulates turbojets, turbofan and ramjets. There's no way to make a SCRAMJET, besides I don't think there is data of a SCRAMJET. So someone needs to show me the data, then I can think of incorporating BJE into AJE and make it.

Same thing goes for propfans and turboprops.

Besides, what is the BahamotoD's pack?

@Dragon01, no. That would break aerodynamics, besides I don't see anything of that sort no covered by TweakScale already.

BahamutoD's "B Dynamics Pack", found here:

http://forum.kerbalspaceprogram.com/threads/82341-24-2-B-Dynamics-Retracting-vectoring-engines-etc-v1-1-1-%28Aug-11%29

The engines are beautiful and sleek, even if there are only 2 jet engines in it.

Concerning the X-51's technical specifications and performance (theoretical and otherwise):

(starting at slide 10) https://www.aiaa.org/uploadedFiles/About-AIAA/Press_Room/Key_Speeches-Reports-and-Presentations/RMutzman_and__JMurphy_X-51_Development_2011.pdf

I know it's not exactly a clean data sheet, and definitely still in prototype phases, but those are the real-world test results from the X-51A (a second flight has been made seince, but I could not find good data on it).

This is a whitepaper by Lockheed from 1987 that has more information about propfan engines than I think anyone would ever want:

http://cafefoundation.org/v2/pdf_tech/Noise.Technologies/NASA.1987.Prop.Noise.PropFan.pdf

And a much more recent and performance-oriented document from 2010:

http://dspace.mit.edu/bitstream/handle/1721.1/58080/639280401.pdf?sequence=1

Let me know if you need more info, and I can go digging. Or if it's just not feasible at this time to implement (too much work/time/effort). And thanks for at least considering these engines!

[Guest]

If every single engine use that, then you cannot use other aero parts to pretend the engine body is buried in the fuselage. If you force the engine fuselage to bury, then extra drag will occur, get it?

Ah, this. Well, I don't see that as a too big of an issue. Jet engines aren't "buried in the fuselage" all that often. They're either podded (not a problem), mounted in wings (also not a problem, you'll surf-attach the engine) or mounted inline, filling up an entire fuselage section. In the latter case, it'd cause some multicoupler problems, but with the introduction of B9 slim Mk2 bicoupler, I think it'd be dealt with easily enough by plane builders. Right now, despite the offset COM, there's no indication just how big those jet engines really are.

Perhaps the config could be optional, for better customization.

[blowfish]

Ah, this. Well, I don't see that as a too big of an issue. Jet engines aren't "buried in the fuselage" all that often. They're either podded (not a problem), mounted in wings (also not a problem, you'll surf-attach the engine) or mounted inline, filling up an entire fuselage section. In the latter case, it'd cause some multicoupler problems, but with the introduction of B9 slim Mk2 bicoupler, I think it'd be dealt with easily enough by plane builders. Right now, despite the offset COM, there's no indication just how big those jet engines really are.

Perhaps the config could be optional, for better customization.

I think a better solution, if you wanted to implement something like this, would be to just add a low-resolution, non-colliding internal engine body to each part. This would encourage the use of properly-sized nacelles. Of course, nothing would keep people from clipping them through fuel tanks, and you'd need something larger then Mk2 to accommodate two engines.

[dreadicon]

Regarding the idea of Jet Engines as their own parts, this sounds like a great idea to me personally. It would be a step towards modular/procedural engines, as you now have 3 parts of an engine to choose: intake, engine, and nozel. Even if the Nozel does little to nothing generally, it's still a factor in the overall implementation of the craft.