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

[camlost]

I'm thinking about configuring the B9 VTOL jet, and the two new propeller engines from FS. Any ideas guys?

[Dirt_Merchant]

maybe think about the vtol jet as the Rolls Royce Pegasus of av8b-harrier fame as a baseline system for the vtol jet, might make it part of a 4 part system like the harrier, maybe re-scale it to half size or something along side that. for the propellers, pt6a or tpe331 (preferably a high shaft horsepower variant) turboprops if not the Pratt & Whitney wasp major 4630 or Wright r-3350 dual cyclone.

[Bloodbunny]

There are two new Firespitter engines? Are you thinking of the Infinite Dice engines?

[camlost]

maybe think about the vtol jet as the Rolls Royce Pegasus of av8b-harrier fame as a baseline system for the vtol jet, might make it part of a 4 part system like the harrier, maybe re-scale it to half size or something along side that. for the propellers, pt6a or tpe331 (preferably a high shaft horsepower variant) turboprops if not the Pratt & Whitney wasp major 4630 or Wright r-3350 dual cyclone.

I can't find the turboprop you're talking about. It's not in the firespitter preview

I think it's also a good idea to change the electric propellers to some fuel-cell driven ones.

[NathanKell]

While you're adding configs, could you also support the (newly bumped) Taverio's Plane Parts pack? It has IIRC a radial jet, a small basic jet and advanced jet, and two sizes of ramjet. (I mostly use the ramjet model as an "early jet nozzle"...)

[Dirt_Merchant]

Snjo shared the files with us on my livestream yesterday. I'll see about getting a dropbox link at you two. Also, InfiniteDice might update the alternative engines after he's worked out things with skillfull, providing there is interest and time.

Edited April 10, 2014 by Dirt_Merchant

[camlost]

While you're adding configs, could you also support the (newly bumped) Taverio's Plane Parts pack? It has IIRC a radial jet, a small basic jet and advanced jet, and two sizes of ramjet. (I mostly use the ramjet model as an "early jet nozzle"...)

What things do you think suit best for them

[NathanKell]

For the small podded jet, something like the J85, really (in its civilian guise, maybe). For the small turbofan, maybe the RB199? Its diameter is in that range. For the small turbojet--well, what about the F404? With vectoring, a la X-31. That's the only reason I can think for it to look like that...

For the ramjets, two ramjets.

[camlost]

I think I found something interesting. Flightgear is an open-source flight simulator. YASim is one of the flight dynamic models Flightgear uses which provides codes for proper simulation of propeller, rotor, piston engine and turboprops. Their jet algorithm is not as good as NASA EngineSim.

So something more to steal from:) I'll try to rewrite AJEPropeller based on this

[jrandom]

Are there any engines that work as SCRAM jets for Mach 5+ operation?

[camlost]

Are there any engines that work as SCRAM jets for Mach 5+ operation?

The algorithm of NASA EngineSim doesn't support supersonic combustion. Unless someone re-write the physical model, or provide accurate performance data (who has it anyway?)

[jrandom]

The algorithm of NASA EngineSim doesn't support supersonic combustion. Unless someone re-write the physical model, or provide accurate performance data (who has it anyway?)

It's all described in a book I have called "Mechanics and Thermodynamics of Propulsion". Since my level of understanding after reading that book is around maybe 2%, I'm afraid I can't actually provide any advice.

Great book, though.

[camlost]

You finished that book in how long? I think I may need a year's time or so to finish this several-hundred-pages book.

[jrandom]

You finished that book in how long? I think I may need a year's time or so to finish this several-hundred-pages book.

Considering I lack a lot of the math (I am now shopping for math books), it took me two months of reading it every morning and evening on my 45-minute bus commute to/from work. I understand a lot of the basic principles/concepts and mechanics, I just can't do the actual specific math for calculations yet.

It's the only engineering book I've ever read that can be called "gripping". Absolutely fantastic.

[Pds314]

Tried this with B9 SABRE M (the 2.5-meter one that you upped to the realistic 2940 kN of thrust), let's just say that turning on SAS is a recipe for being instantly vaporized by hitting a wall of mach 5 air at sea level.

Also, not sure if you're aware, but 2 F-22 engines on an appropriate B9 fuselage and reasonable wings can, in-game, cruise supersonic at sea level, and hit mach 2 with full afterburner on at that altitude. Are you sure that is realistic? I know that the real F-22 has never been claimed able to reach such ludicrous speeds at sea level. Maybe I have smaller intakes than real ones?

Oh wow! I tried making a twin-engined "fighter" that uses the realistic SABRE Ms... 30 meters long, 20 meters in wingspan, extremely agile, only 25 tonnes with 5.2 tonnes of H2 onboard that can be burned through in well under a minute if necessary. 740 Billion Joules can be gone in a matter of seconds.

I then tried, in a single run, getting to 1670 m/s several times, reaching an altitude of 166 km, and flying 800 km to Northwestern Georgia on that tank of fuel. I also managed to get a 27-G maneuver...

Oh, speaking of which. 25 tonnes and a nominal maximum of 600 tonne-force of thrust gives the entire vehicle a comparable TWR to a stock mainsail.

During overthrust, for very brief periods, the thrust may be up to 2.5 times that, meaning it is accelerating at 720 m/s^2, again, only for brief periods. The pilot would probably have broken bones from that overthrust if they didn't absorb the force perfectly.

Of note: the dynamic pressure is a crushing 15 atmospheres. You want to know what Jool will do to something with a vacuum on one side? Put it on the front of this "fighter."

You know, come to thing of it, it might make a better ultra-low-altitude bomber than a fighter. Afterall, it is controllable enough that it could probably just fly through a city and kill anyone within a hundred meters and smash buildings due to sonic boom, or it could just kamikaze several tonnes of extremely flammable hydrogen into things, afterall, it has the equivalent of over 1% of a Hiroshima-destroying bomb worth of very easily vaporized and ignited flammables onboard and it is moving fast enough to autoignite on impact.

Edited April 16, 2014 by Pds314

[Pds314]

Oh yeah, so to clarify, does a copy of NASA enginesim run for each engine?

[camlost]

All the engine data (thrust and SFC) are from public data. Although they cannot be 100% accurate, I don't expect the error bigger than 10%-20% at any point. All your problems come from overall design instead of engine performance alone.

1. All airplanes have max dynamic pressure. F-22 cannot fly at M2.0 at sea level because its structure cannot take it, not because it lacks thrust. Maybe you should talk to DRE guys about implementing a "dynamic pressure" limit to wing parts.

2. The SABREs are supposed to push 300-tonnes off the runway and to the earth orbit. They have very high TWR by design. 25-tonnes is too light for two SABRE Ms and 5.2 tonnes of H2 is too little. The skylon is supposed to have 85% of the takeoff mass being LH2+LOx.

With FAR and AJE, I'm pretty sure that reasonable aircraft designs give reasonable performance and bad designs have bad performance.

Each engine has its own calculation.

[Dirt_Merchant]

Tried this with B9 SABRE M (the 2.5-meter one that you upped to the realistic 2940 kN of thrust), let's just say that turning on SAS is a recipe for being instantly vaporized by hitting a wall of mach 5 air at sea level.

Also, not sure if you're aware, but 2 F-22 engines on an appropriate B9 fuselage and reasonable wings can, in-game, cruise supersonic at sea level, and hit mach 2 with full afterburner on at that altitude. Are you sure that is realistic? I know that the real F-22 has never been claimed able to reach such ludicrous speeds at sea level. Maybe I have smaller intakes than real ones?

Oh wow! I tried making a twin-engined "fighter" that uses the realistic SABRE Ms... 30 meters long, 20 meters in wingspan, extremely agile, only 25 tonnes with 5.2 tonnes of H2 onboard that can be burned through in well under a minute if necessary. 740 Billion Joules can be gone in a matter of seconds.

I then tried, in a single run, getting to 1670 m/s several times, reaching an altitude of 166 km, and flying 800 km to Northwestern Georgia on that tank of fuel. I also managed to get a 27-G maneuver...

Oh, speaking of which. 25 tonnes and a nominal maximum of 600 tonne-force of thrust gives the entire vehicle a comparable TWR to a stock mainsail.

During overthrust, for very brief periods, the thrust may be up to 2.5 times that, meaning it is accelerating at 720 m/s^2, again, only for brief periods. The pilot would probably have broken bones from that overthrust if they didn't absorb the force perfectly.

Of note: the dynamic pressure is a crushing 15 atmospheres. You want to know what Jool will do to something with a vacuum on one side? Put it on the front of this "fighter."

You know, come to thing of it, it might make a better ultra-low-altitude bomber than a fighter. Afterall, it is controllable enough that it could probably just fly through a city and kill anyone within a hundred meters and smash buildings due to sonic boom, or it could just kamikaze several tonnes of extremely flammable hydrogen into things, afterall, it has the equivalent of over 1% of a Hiroshima-destroying bomb worth of very easily vaporized and ignited flammables onboard and it is moving fast enough to autoignite on impact.

This, for whatever reason was an extremely fun read lol. I like your style!

[Pds314]

This, for whatever reason was an extremely fun read lol. I like your style!

Thanks. You should see XKCD's "what if" section. I think my writing style is heavily influenced by it.

[Pds314]

All the engine data (thrust and SFC) are from public data. Although they cannot be 100% accurate, I don't expect the error bigger than 10%-20% at any point. All your problems come from overall design instead of engine performance alone.

1. All airplanes have max dynamic pressure. F-22 cannot fly at M 2.0 at sea level because its structure cannot take it, not because it lacks thrust. Maybe you should talk to DRE guys about implementing a "dynamic pressure" limit to wing parts.

2. The SABREs are supposed to push 300-tonnes off the runway and to the earth orbit. They have very high TWR by design. 25-tonnes is too light for two SABRE Ms and 5.2 tonnes of H2 is too little. The skylon is supposed to have 85% of the takeoff mass being LH2+LOx.

With FAR and AJE, I'm pretty sure that reasonable aircraft designs give reasonable performance and bad designs have bad performance.

Each engine has its own calculation.

On the contrary, the vehicle is barely half made of engines.

[Dirt_Merchant]

Oh yeah, "what if" is one of my favorite reads on the internet. Anyone ignorant to it is really missing out.

[plausse]

I went through most of the thread, but could not find my issue. If I missed it and it is in fact there, I do apologise. So:

I have latest version of FAR, Realfuels and HotRockets, I use the "stock" engine config for real fuels. The problem only occurs with AJE installed, and not with only the other mods. When I use either the RAMjet or the other 1.25m engine (using the stock enginemodel), I get smoke effects and flame out effects in the VAB. Also the engine does not show up in the staging sequence, and when I start a flight I immediately flame out even though the plane has intakes and is loaded with kerosene. All the B9 engines work great, as well as the firespitter prop engines, and the small turbojet (despite using the same model as one that does not work).

I have thought deep and hard but have no clue. Does it have anything to do with a plugin like Exurgent engineering or something? Are there 100 gnomes on my loft? What is going on? If anyone understands this and could help me, I would owe them an imaginary cookie...

[camlost]

I went through most of the thread, but could not find my issue. If I missed it and it is in fact there, I do apologise. So:

I have latest version of FAR, Realfuels and HotRockets, I use the "stock" engine config for real fuels. The problem only occurs with AJE installed, and not with only the other mods. When I use either the RAMjet or the other 1.25m engine (using the stock enginemodel), I get smoke effects and flame out effects in the VAB. Also the engine does not show up in the staging sequence, and when I start a flight I immediately flame out even though the plane has intakes and is loaded with kerosene. All the B9 engines work great, as well as the firespitter prop engines, and the small turbojet (despite using the same model as one that does not work).

I have thought deep and hard but have no clue. Does it have anything to do with a plugin like Exurgent engineering or something? Are there 100 gnomes on my loft? What is going on? If anyone understands this and could help me, I would owe them an imaginary cookie...

Thank you for your support of this mod. The issue you spoke of happens a lot when I'm debugging AJE. The problem is coming from multiple addons changing cfg files. Specifically, it happens when a part has "ModuleEnginesFX" but some plugin thought it uses the old "ModuleEngines" then trying to do something to it. And that plugin is not AJE, as it automatically recognizes ME or MEFX using a "EngineWrapper" class.

So to troubleshoot,

1.Make sure you have all the mods installed correctly and updated, including moduleManager, of which you should keep only one copy

2. See what happens if you remove HotRockets following the guide in OP. By removing HotRockets, all parts will be using the old ME thus eliminate compatibility issues.

3. If removing HR makes it work that's probably compatibility problem from Tweakable Everything, Throttle controlled avionics , etc.

4. If still doesn't work, open Debug, find PARTS->Stock/Parts/Engines/JetEngine.cfg and report what you see. You should either find one "ModuleEngines" or one "ModuleEnginesFX" depending on whether you have HR, and no other junk or multiple engine modules.

[Taverius]

As the balancer for B9 and major jet-nerd, I approve.

[Guest]

Have you seen this?: http://forum.kerbalspaceprogram.com/threads/24906-WIP-LLL-Lack-Luster-Labs-LLL-12-Pre-Release-Testing-SXT-12-19APR2014

There is a couple of jet engines in the SXT pack. Any chance of getting an AJE config for them?