Your Nation's Air Force Mark III: Best Korea Edition

[Pavelania]

So, alternative engines?

Yes by the looks of it I advise using the F135 if you can. That or develop your own engine. For most of our latest fighters we use the GE 404 for our FA-03A/B Leopard and FA-01M/N Fisker, but our newer FA-03 Super Leopard and Panther will use the upgraded GE F414 (the upgraded 20% more thrust variant used for the F-18 ASH) for the new powerplant instead of the F404. The upcoming Super Fisker and Vipe will use the GE F110 instead of the GE F404.

[Pavelania]

Oh ok.

If you have the ability to reduce the radar cross section of your aircraft with nothing more complicated then a coat of paint then you do it.

The USAF recently upgraded the SEAD variant of the F-16 with the same RAM paint used on the F-35.

Oh wow thats pretty cool!

[The Technocratic Syndicalists]

So, alternative engines?

you could use two F135s, they just wouldn't be ideal for supercruising with their 0.57:1 bypass ratio. If you want to supercruise then you want the F119 or better the F120. The F120 actually has about the same amount of dry thrust as the F135 (~125 kN). The downside is that the F119 and F120 have around 85% of the afterburner thrust of the F135 so your combat T/W ratio will be slightly worse. Fuel consumption for both at subsonic speeds is also slightly worse (due to the lower bypass ratio, around 0:31:1) so your subsonic cruise range would also suffer slightly.

[Pavelania]

So, alternative engines?

you could use two F135s, they just wouldn't be ideal for supercruising with their 0.57:1 bypass ratio. If you want to supercruise then you want the F119 or better the F120. The F120 actually has about the same amount of dry thrust as the F135 (~125 kN). The downside is that the F119 and F120 have around 85% of the afterburner thrust of the F135 so your combat T/W ratio will be slightly worse. Fuel consumption for both at subsonic speeds is also slightly worse (due to the lower bypass ratio, around 0:31:1) so your subsonic cruise range would also suffer slightly.

By the way whats better, the GE F110 or the P&W F100? Seems like the F110 has more thrust so I'm assuming its better.

[New Vihenia]

Is that an attempt at dazzle camouflage? IIRC the two-tone grey "Compass Ghost" used by the USAF and USN is the most effective camouflage paint scheme for aircraft. Blue is bad because it sticks outs quite a bit in clouds and in overcast weather conditions.

definitely not. i just slap US navy's uniform camo at there.

[Rich and Corporations]

if you want to learn about large caliber aircraft guns: http://www.quarryhs.co.uk/Grabin.htm

(with advancements in timed fuses, large caliber guns may have use once more)

[The Technocratic Syndicalists]

By the way whats better, the GE F110 or the P&W F100? Seems like the F110 has more thrust so I'm assuming its better.

The latest F110 variant, the F110-GE-132 (used on the latest F-16s) has more thrust than the latest F100 variant, the F100-PW-229 (145 vs 130 kN). For the F110-GE-129 it's about the same as the F100-PW-229. The biggest difference between the two is the bypass ratio. For the F110-GE-132 and F110-GE-129 is around 0.70:1 whereas for the F100-PW-229 it's much lower at 0.36:1. So the F100 will give you better high-end supersonic performance. As far as size, fuel consumption, and weight are concerned they're pretty much identical (the F110-GE-132 is about 100kg heavier than the F110-GE-129 and the F100-PW-229). The F110-GE-132 actually uses technology from the F120, F136, and F414 whereas the F100-PW-229 borrows a lot from the F135 and F119. Personally my recommendation would be the F110-GE-132 for a subsonic/transonic optimized fighter (F-16) and the F100-PW-229 for a mach 2+ high end supersonic fighter like an F-15.

Something to keep in mind is that judging engines based solely on their thrust rating can be misleading. The thrust rating for engines usually represents they're uninstalled sea-level static thrust. They basically take the engine, place it on a test stand, put in max afterburner and the measure how thrust it can produce with a given safe TIT and compressor RPM limit. When you're dealing with the engine under operational conditions things begin to change. With a turbojet or low bypass turbofan engine with zero bypasses thrust will decrease as you approach M0.5 then begin to increase as you go faster and faster. With a higher bypass turbofan thrust will continuously decrease as you go faster beyond static. So while a higher bypass turbofan may have better sea-level static thrust at cruise it's thrust may be worse than a lower-bypass turbofan with a lower sea-level static thrust rating. I'll give you an example: The British F-4K phantom with its sprey turbofans has more sea-level static thrust than the american F-4 phantom with its J79 turbojets yet the F-4K has a lower cruising speed and a lower climb rate. Why? At cruise the J79 produces more thrust because it's a turbojet with zero bypass while the F-4K is a turbofan with a moderate amount of bypass. On the other hand the sprey has a lower SFC so the range of the F-4K is slightly higher than the F-4s with the J79.

Now if you want the best of both worlds (ie higher bypass for better fuel efficiency, lower bypass for higher specific thrust) then you want a variable-cycle turbofan (sometimes refereed to as a VCE or variable cycle engine). Currently the only variable-cycle engine ever put on an operational aircraft was the J58 of the SR-71 which was a type of bleed-bypass turbojet. The GE F120, which competed in the ATF competition with the P&W F119, was a variable-cycle turbofan that had what can be roughly described as a simplified version of the J58's bleed-bypass system (it used these things called variable-area bypass injectors or VABIs along with a split-fan arrangement which allowed the engine to change its bypass ratio in flight). GE is currently working on another VCE called the "adaptive cycle engine" under the USAF's Adaptive Engine Technology Development (AETD) which is expected to be fitted to future blocks of the F-35. So if you want a fancy high performance engine for a modern fighter jet this is probably what you should be looking into.

[Theodosiya]

SO, for mah high end supe?

[Gallia-]

One paintscheme concept for our Shelenia Meia. Export fighter

(Image)

Is that an attempt at dazzle camouflage? IIRC the two-tone grey "Compass Ghost" used by the USAF and USN is the most effective camouflage paint scheme for aircraft. Blue is bad because it sticks outs quite a bit in clouds and in overcast weather conditions.

it isnt hue it's tone

grey just became fashionable because making it any other hue doesnt help (nor detract, either) and requires more work

a less saturated blue like air superiority blue would work fine

[Pavelania]

By the way whats better, the GE F110 or the P&W F100? Seems like the F110 has more thrust so I'm assuming its better.

The latest F110 variant, the F110-GE-132 (used on the latest F-16s) has more thrust than the latest F100 variant, the F100-PW-229 (145 vs 130 kN). For the F110-GE-129 it's about the same as the F100-PW-229. The biggest difference between the two is the bypass ratio. For the F110-GE-132 and F110-GE-129 is around 0.70:1 whereas for the F100-PW-229 it's much lower at 0.36:1. So the F100 will give you better high-end supersonic performance. As far as size, fuel consumption, and weight are concerned they're pretty much identical (the F110-GE-132 is about 100kg heavier than the F110-GE-129 and the F100-PW-229). The F110-GE-132 actually uses technology from the F120, F136, and F414 whereas the F100-PW-229 borrows a lot from the F135 and F119. Personally my recommendation would be the F110-GE-132 for a subsonic/transonic optimized fighter (F-16) and the F100-PW-229 for a mach 2+ high end supersonic fighter like an F-15.

Something to keep in mind is that judging engines based solely on their thrust rating can be misleading. The thrust rating for engines usually represents they're uninstalled sea-level static thrust. They basically take the engine, place it on a test stand, put in max afterburner and the measure how thrust it can produce with a given safe TIT and compressor RPM limit. When you're dealing with the engine under operational conditions things begin to change. With a turbojet or low bypass turbofan engine with zero bypasses thrust will decrease as you approach M0.5 then begin to increase as you go faster and faster. With a higher bypass turbofan thrust will continuously decrease as you go faster beyond static. So while a higher bypass turbofan may have better sea-level static thrust at cruise it's thrust may be worse than a lower-bypass turbofan with a lower sea-level static thrust rating. I'll give you an example: The British F-4K phantom with its sprey turbofans has more sea-level static thrust than the american F-4 phantom with its J79 turbojets yet the F-4K has a lower cruising speed and a lower climb rate. Why? At cruise the J79 produces more thrust because it's a turbojet with zero bypass while the F-4K is a turbofan with a moderate amount of bypass. On the other hand the sprey has a lower SFC so the range of the F-4K is slightly higher than the F-4s with the J79.

Now if you want the best of both worlds (ie higher bypass for better fuel efficiency, lower bypass for higher specific thrust) then you want a variable-cycle turbofan (sometimes refereed to as a VCE or variable cycle engine). Currently the only variable-cycle engine ever put on an operational aircraft was the J58 of the SR-71 which was a type of bleed-bypass turbojet. The GE F120, which competed in the ATF competition with the P&W F119, was a variable-cycle turbofan that had what can be roughly described as a simplified version of the J58's bleed-bypass system (it used these things called variable-area bypass injectors or VABIs along with a split-fan arrangement which allowed the engine to change its bypass ratio in flight). GE is currently working on another VCE called the "adaptive cycle engine" under the USAF's Adaptive Engine Technology Development (AETD) which is expected to be fitted to future blocks of the F-35. So if you want a fancy high performance engine for a modern fighter jet this is probably what you should be looking into.

Oh ok thanks for the info! Hate to admit it now but that was how I judged jet engines, by the amount of thrust. But now I know. Thanks!

So I might have my single engine mach 1 F-01 Super Fisker/Viper use the GE F110, while the twin engine mach 2 FA-03 Super Leopard/Panther might use the F414 or the F100-PW-229.

[The Technocratic Syndicalists]

Oh ok thanks for the info! Hate to admit it now but that was how I judged jet engines, by the amount of thrust. But now I know. Thanks!

Sea level static thrust is still important when sizing an engine for takeoff performance. It's just not the only thing you should look at when evaluating competing engines.

So I might have my single engine mach 1 F-01 Super Fisker/Viper use the GE F110, while the twin engine mach 2 FA-03 Super Leopard/Panther might use the F414 or the F100-PW-229.

That's basically what the USAF has with the F-16 and F-15E. If these are newer aircraft you could also use the F135 for the F-01 and the F119 or F120 for the FA-03. The F135/F119/F120 weigh about the same as the F100/F110 and are similar in external dimensions (they're slightly longer than the F100 and F110) but have the advantage of significantly higher thrust ratings and T/W ratios.

[Rich and Corporations]

Fuel efficiency is the most important statistic on an aircraft.

[The Technocratic Syndicalists]

Fuel efficiency is the most important statistic on an aircraft.

If that were true fighters would all use high bypass turbofans. Fuel efficiency is important for airliners, airlifters, and strategic bombers. For fighter jets the most important engine characteristics are specific thrust and thrust/weight. Fuel efficiency is still important, if it weren't we'd still be using turbojets, but it isn't the primary design driver.

The trend since turbofans have been introduced in fighter aircraft has actually been lower and lower bypass ratios (bad for fuel efficiency) with higher and higher pressure ratios (good for fuel efficiency). For what it's worth the F119 has a higher dry SFC than the F110 which itself has a higher dry SFC than the TF30, the first afterburning turbofan put into service (to be fair the F119 and F110 have a lower wet SFC than the TF30 although for the F119 it's still higher than the F110). So fuel efficiency overall hasn't improved much (or at all) in 30+ years of fighter engine evolution. On the other hand the F119 has a significant higher T/W and specific thrust compared to the F110 which in turn has a higher T/W and specific thrust than the TF30. So you can clearly see what's considered important when it comes to fighter jet engine design.

[The Akasha Colony]

SO, for mah high end supe?

Use F135/F136 or F119/F120. You haven't really demonstrated any need for higher thrust than those engines offer, which is already greater than what any other fighter engine offers.

[Laritaia]

Go Go RE Scimitar powered fighter.

[The Technocratic Syndicalists]

Go Go RE Scimitar powered fighter.

Air to air refueling with LH2 would be....interesting.

[Rich and Corporations]

Fuel efficiency is the most important statistic on an aircraft.

If that were true fighters would all use high bypass turbofans. Fuel efficiency is important for airliners, airlifters, and strategic bombers. For fighter jets the most important engine characteristics are specific thrust and thrust/weight. Fuel efficiency is still important, if it weren't we'd still be using turbojets, but it isn't the primary design driver.

The trend since turbofans have been introduced in fighter aircraft has actually been lower and lower bypass ratios (bad for fuel efficiency) with higher and higher pressure ratios (good for fuel efficiency). For what it's worth the F119 has a higher dry SFC than the F110 which itself has a higher dry SFC than the TF30, the first afterburning turbofan put into service (to be fair the F119 and F110 have a lower wet SFC than the TF30 although for the F119 it's still higher than the F110). So fuel efficiency overall hasn't improved much (or at all) in 30+ years of fighter engine evolution. On the other hand the F119 has a significant higher T/W and specific thrust compared to the F110 which in turn has a higher T/W and specific thrust than the TF30. So you can clearly see what's considered important when it comes to fighter jet engine design.

a tenth to a fourth of the mass of an aircraft is the fuel

the F119 is nearly two tonnes, a tenth of the weight of the aircraft

afterburning is good for evading anti air missiles, but after a certain point, you're going to end up with SR-71s firing anti air missiles after each other from 10,000 miles away.

there are real diminishing returns, and you need range for naval operations and for combat in the wastelands of a nation, where there is not many airports.

[Pavelania]

That's basically what the USAF has with the F-16 and F-15E. If these are newer aircraft you could also use the F135 for the F-01 and the F119 or F120 for the FA-03. The F135/F119/F120 weigh about the same as the F100/F110 and are similar in external dimensions (they're slightly longer than the F100 and F110) but have the advantage of significantly higher thrust ratings and T/W ratios.

I wouldn't mine choosing the F135, F119, or the F120, but I'm pretty sure they aren't available for export or development for any other fighters other than the F-35, F-22, YF-23. What I mean is that GE/P&W would only allow these engines for the fighter their meant for. Plus only 507 F119s have been built ONLY for the F-22, and the YF120 is not in development (YF120 would've been a hell of an engine), and the F135 seems to only be for the F-35.

[Pavelania]

Wow would've been awesome if the YF120 was chosen over the F119. Gosh the YF-23 is so gorgeous compared to the YF-22. Modern F-22 looks really awesome, but I wish they somehow could've chosen both in a way. On thing I have noticed about Northrop Grumman, is that they always have really advanced aircraft designs, like the YF-23, B-2, their 6th Gen fighter concept, while yes Lockheed Martin, especially Skunk Works, build and test advanced aircraft, but there 6th gen fighter concept is more traditional looking.

[Rich and Corporations]

That's basically what the USAF has with the F-16 and F-15E. If these are newer aircraft you could also use the F135 for the F-01 and the F119 or F120 for the FA-03. The F135/F119/F120 weigh about the same as the F100/F110 and are similar in external dimensions (they're slightly longer than the F100 and F110) but have the advantage of significantly higher thrust ratings and T/W ratios.

I wouldn't mine choosing the F135, F119, or the F120, but I'm pretty sure they aren't available for export or development for any other fighters other than the F-35, F-22, YF-23. What I mean is that GE/P&W would only allow these engines for the fighter their meant for. Plus only 507 F119s have been built ONLY for the F-22, and the YF120 is not in development (YF120 would've been a hell of an engine), and the F135 seems to only be for the F-35.

do what the chinese do and produce a knockoff

[Pavelania]

I wouldn't mine choosing the F135, F119, or the F120, but I'm pretty sure they aren't available for export or development for any other fighters other than the F-35, F-22, YF-23. What I mean is that GE/P&W would only allow these engines for the fighter their meant for. Plus only 507 F119s have been built ONLY for the F-22, and the YF120 is not in development (YF120 would've been a hell of an engine), and the F135 seems to only be for the F-35.

do what the chinese do and produce a knockoff

Yea we could do that but we don't want to be labeled copycats.

[Pavelania]

Plus we don't really have any engine manufactures, although if we were to do that, I guess PAC Aviation Systems could possibly manufacture the engine.

[Rich and Corporations]

well, NS is a libertarian world, I'm sure you can find someone to produce engines or similar engine designs for you.

[The Greater Siriusian Domain]

OOC: In regards to forward-swept wings, the tech demonstrators I've seen all had relatively long and narrow wings at an extreme angle. I've been experimenting with a FSW design in KSP that has a shallower angle with wide, somewhat shorter wings akin to a conventional fighter. It's been pretty promising.

http://images.akamai.steamusercontent.c ... AED459ED5/

[Pavelania]

well, NS is a libertarian world, I'm sure you can find someone to produce engines or similar engine designs for you.

Yea possibly. Although I would love a Variable Cycle Engine. My older F-01 Fiskers just had an open inlet similar to an F-86 or Mig-15/17, but the new Super Fisker will have a splitter-plate style inlet like an F-16, while the Viper variant will have a DSI Inlet. My FA-03 Leopard also currently uses a variable inlet like an F-4 Phantom, but I think the Super Leopard may keep it, but the Panther will get DSI inlets similar to an F-35.