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S. Korea’s New Stealth Fighter Design

by John Reed on October 21, 2011

Check out these pictures that Steve Trimble snapped of the latest stealth fighter design to hit the international market. They pics show Korean Aircraft Industries’ proposed stealthy next-gen fighter that was unveiled at the Seoul Air Show this week. South Korea plans to field the plane, dubbed KF-X, in the next nine years as a replacement for it’s Vietnam War-era F-4 Phantom IIs and F-5E Tiger IIs. Going from fighters that first flew in the late 1950s and 1960s to a stealthy design resembling some sort of twin-engined F-35 Joint Strike Fighter, as Trimble puts it, is quite the leap. In addition to KAI, Eurofighter is also bidding a design for KF-X. In an example of how stealth fighters will be all over the place by the 2020s, Indonesia is already a partner in the program and F-35-buyer Turkey may join the KF-X effort soon. Seoul wants the KF-X to carry locally developed air-to-air missiles, guided bombs and anti-ship missiles. That’s right, a new fleet of stealth jets with new weapons in just nine years.

Keep in mind that South Korea is also looking at buying 40 to 60 Sukhoi PAK FAs, F-35s or F-15SE Silent Eagles under its F-X program which is supposed to kick off next year.

Click here for more info on the jet.

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{ 83 comments… read them below or add one }

blight October 21, 2011 at 12:24 pm

Definitely ambitious. New weapons, new aircraft, and a 5B budget?

If they can get it done, maybe we should figure out what they're doing right and what we're doing wrong. Then again, we can still pitch our -35B's for the Dokdos, and if you have the -35B you may as well add the -A for your ground troops if you're in the market for a new air force.


ospreyluvr October 21, 2011 at 12:45 pm

It may be cheaper for them to buy this KF-X instead of the F-35A. Then again, having all your planes built off the same platform makes maintenance simpler. Has ROK had their very own plane in the past few decades?


blight October 21, 2011 at 12:51 pm

KT-1 and T-50 Golden Eagle. Possibly others.


wqedsd October 21, 2011 at 4:58 pm

even countries who are considered close allies to the US need to consider avoiding dependence. who knows what will happen in politics.


Tad October 24, 2011 at 11:01 am

I think that what they're doing right is they have a broad and growing industrial base with all the associated technical and engineering expertise that go with it. The US has a declining base and so is left with few people having the technical, engineering, manufacturing and associated administrative know-how.


ospreyluvr October 21, 2011 at 12:44 pm

Looks like a F-35 with hints of the F-16. I like it! I hope that ROK goes with either the F-35 or F-15SE for the F-X program, but it is great to see them working on developing their own stealth aircraft. I doubt the aircraft can compete with the likes of the F-35 or F-22, but it could be a cheap stealth alternative to the F-35. Looking forward to hearing more from this craft.


Zap October 21, 2011 at 12:51 pm

Turkey have already said they won't take part unless they are a equal partner


tiger October 21, 2011 at 1:16 pm

All those years of Selling Hyundai's is paying off….
Long term we seem to have a trend of 3rd tier nations like Iran, Pakistan & now South Korea domestically producing jets. Leaving the US & Mig with nobody to sell to.


So? October 22, 2011 at 3:03 am

MiG is kaput.


Hermeticus October 25, 2011 at 12:29 pm

I wouldn't describe South Korea as a 3rd tier nation. Seoul is the 2nd largest city in the world and very modern. I think they are 1st tier.


Dfens October 21, 2011 at 1:58 pm

Either they plan on these fighters going on a one way trip toward the enemy and not coming back, or they figure they'll be so badass they won't leave any threats behind. I'm thinking the former instead of the latter. But what the hell, you can probably buy a dozen for the price of an F-35.


melcyna October 23, 2011 at 7:11 am

somehow i don't think a country who is still in a state of war and has one of the most unpredictable and dangerous neighbor will do a project that doesn't give a solid result.


Dfens October 23, 2011 at 8:15 am

Too bad politics doesn't trump physics then, isn't it? Maybe they can do like the flying taco chip (A-12) was supposed to and never fly directly away from the enemy. It's just as great an idea now as it was then.


melcyna October 23, 2011 at 8:35 am

or a second possibility would be that they have internal bay alright, but still can mount external payload and the model shows both?

who knows, i mean technically since the country would most likely want 1 multi role fighter if possible that's not too far fetched.

internal payload only for the strike, then the following sorties or planes can be mounted with external payload for maximum ordnance delivery once there is a safe corridor.


melcyna October 23, 2011 at 8:38 am

either way though, for a country that's under constant threat and have been 'attacked' even in this stalemate condition several times now, whatever planes come out of this would have to be combat ready since aside of massive artillery the NK also have very dense air defense.


Joe October 21, 2011 at 2:29 pm

First impressions can be wrong, but this sort of reminds me of the Yak-38 Forger, the Soviet vertical take off fighter that could only carry 2200lbs of weapons. Sure it's stealthy, but what good will that stealth do if it can't carry any weapons behind enemy radar?


Lance October 21, 2011 at 2:48 pm

Looks more like a mini F-22 than a copy of a F-35. good for ROK. But do they have the resources to build such a complex thing as a stealth fighter? Other nations tried and failed to build such planes have to wait and see.


brianckramer October 21, 2011 at 2:59 pm

At least THEY were smart enough to put two engines in it… F35?


ospreyluvr October 21, 2011 at 4:03 pm

One engine can be just as good as two. F-16 anyone?


brianckramer October 21, 2011 at 4:11 pm

yeah…not really…


"The F-16 is known in Air Force circles as the “lawn dart” for its tendency to plunge back to Earth when its single engine flames out, and in most years, engine failure causes more accidents than any other factor."

"In the late 1990s and the early part of this decade, engine problems caused the number of F-16 Class A crashes to spike to as many as 18 in one year"


XYZ October 21, 2011 at 5:27 pm

Still one of THE best fighters ever made, so…

In any design, there are trade-offs that must be made. I'm not disputing your figures or logic, I'm just saying having another engine sacrifices in other areas.


brianckramer October 21, 2011 at 6:10 pm

Like what? All of our bombers and current gen fighters have multiple engines except f16/f35.

What's the tradeoff? What's the benefit of one engine over two? Don't say cost.

Josh October 21, 2011 at 3:31 pm

I can’t help but think all these new designs coming out of smaller countries are just 4th gen fighters Ina shiny new stealth lookalike body. The coatings,materials and tech needed for a truly stealth aircraft are immensely expensive. Plus electronics and an engine that’s capable of a good PtW ratio is a tall order for any military,especially a small one. I somehow see them buying F-15′s or F-35′s when this project runs over budget and behind schedule.


ospreyluvr October 21, 2011 at 4:05 pm

These aircraft won't have the stealth abilities that the F-22 and F-35 have. That seems pretty obvious. However, they are doing the best with what they have and are getting as close as they can within their budget. I agree, for the most part. The Russian PAK and J-20 are the only foreign stealth fighters I see as anywhere near as stealthy as the F-35


STemplar October 21, 2011 at 4:30 pm

As long as you can breathe while you're flying it or it doesn't bankrupt them it will be doing better than the F22/35 on a couple counts.


tiger October 21, 2011 at 5:15 pm

Hey they all read the same text books and likely go to engineering school in the USA. The world has caught up…. In 40 years China has gone from Nixon opening the place to building huge Dams & a space program.


Fluoro Ninja October 22, 2011 at 4:47 am

Sooo… instead of waiting for their own programs to potentially run over budget, they should sign up to one that already has, and jaw-droppingly so? The JSF has redefined what the term 'over budget' can mean.

As an Aussie I'm firmly with the Koreans on this one. If the US won't let it's most trusted friends and allies play with the best kit it makes (F-22) we really should be looking for alternatives to the grossly over priced and under performing JSF, now matter how politically insensitive that may be.

Then again, if L-M was prepared to sell the JSF at the originally quoted price of $60M USD I'd happily advocate for Aus to buy 200 of the things. At almost three times that price the correct number of airframes is zero.


Robert A. Fritts October 24, 2011 at 3:48 am

Do you really need "stealth" when you have a long common border with your enemy and your capital can be hit by Tube artillery North of that border. No you dont.
Reminds me of the USAF's astonishment that the Israeli Airforce wanted its own or to Modify to their specs the American Radars in the F-15. No need for long range super Radars when your country is 45 minutes from the closest enemy airfield by truck. We are so spec driven here in the USA. How mant aircraft(cars, motorcylces, boats, ships,etc) have had all the correct specs,but did not work. ROK wants to build its aerospace industry, good for them. Hopefully the USA wont barrow Chinese money and fund their ally's program.


tiger October 24, 2011 at 7:46 am

Why buy American? Congress puts strings on arms deals. That is part of the reason India passed on our jets.


Josh October 21, 2011 at 3:33 pm

FYI I’m not downing on the south Koreans,I feel all our allies should be striving for technology. But this is a very tall order. Best of luck!


Andrew M October 21, 2011 at 4:20 pm

External weapons defeats the purpose of stealth, they should just maximize maneuverability and aerodynamics and call it a day


blight October 21, 2011 at 10:12 pm

They're designing new missiles too: so if they opt for stealth casings and stealth mountings, it might not be so bad.


jakoye23 October 21, 2011 at 4:27 pm

Have they even built a plane before? Seems kind of a reach to building a stealth fighter from scratch.

I'll log this one up as a "dream machine" that never sees the light of day.


FormerDirtDart October 21, 2011 at 9:44 pm

Just a few. KAI built the KF-16, is responsible for 40% of the production & 25% of the assembly of the F-15K , they developed and build the T-50 Golden Eye. And, that's just the supersonic fighter/multirole aircraft.


So? October 22, 2011 at 3:12 am

20 years ago Korean cars were junk. Where there is a will, there is a way.


Mastro October 21, 2011 at 4:29 pm

Didn't they just start making the T-50?

Talk about ambitious-

If Taiwan and India have had so much trouble with their indigenous programs- I'm a bit skeptical about this on-

Maybe they are trying to mess with North Korea's minds? They are really being left behind- isn't half their airforce still MIG 17's?


Hurrah October 22, 2011 at 12:30 pm

I think South Korea is well aware that the problem with North Korea isn't their airforce.

It's the unless amount of 'stupid' artillery, and a few nukes. When you consider that, it seems like the billions designated for a stealth fighter are a waste. Better be working on unbeatable CRAM and anti-ballistic missile technology and deploy them massively.


melcyna October 23, 2011 at 7:21 am

defensive posture is never a long term solution in any war, in any conflict in general except to buy time for offensive or to increase offensive move effectiveness as a counter attack.

you have to strike, and strike hard if you want to stop a threat… it's good to have point defense and other defensive means to reduce damage to your infrastructure, but that doesn't help much if you can't strike back and just keep being pummeled.


roland October 21, 2011 at 6:06 pm

Just a taught while I am drinking my tea: Why wait nine years when they are already been threaten by North Korea 9 years past to present?


roland October 21, 2011 at 6:45 pm

They (SK) should have bought our (USA) F-35B, F-22,F-18, F15 eagle or YF-23 for their country's defense.


Robert A. Fritts October 24, 2011 at 3:50 am

Tell us why?


blight October 24, 2011 at 7:43 am

I'm surprised you don't advocate they buy both F-22 and YF-23 this time around. Bravo.


marvel October 21, 2011 at 7:36 pm

Looks like the F-35, F-22, F-18 and Su-27 had a baby.


Tee October 21, 2011 at 8:47 pm

Looks like the twin engine version of the Saab Stealth fighter the Saab and S. Korea went it to partnership with Indonesia to build. Here are a few links to testing of a 1:13 scaled demonstrator of a stealth fighter concept designed by Saab.

I'm looking for the other links to the twin engine


Dan October 21, 2011 at 11:46 pm

the first picture looks a lot like the xf-23 just without the triangular wings


Anthony October 22, 2011 at 1:31 am

Part of that new trade agreement with the USA I bet, eh? Maybe we are going to generate some income selling Stealth tech to S Korea. Bonus the increased military buffer against North Korea and China…Sounds Great! Lets see how their defense industry handles itself – what will they learn from the US…our groundbreaking technology or our greedy fatcats and politicians who allow Billions in cost overruns. Let the engineers lead the way, and S Korea could develop a thriving aviation industry. Good Luck!


Nick October 22, 2011 at 2:03 am

As others have said before, conformal weapons bays like SE. And centerline pod maybe? Could get out 3-6 missiles and then run?


Letsallbefriends October 22, 2011 at 3:42 am

At least it’ll come with a decent warranty.


EJ257 October 22, 2011 at 7:42 pm

Flying 600mph you'll be surprise how quickly you'll hit 100K miles ;)


oppervlakkig October 22, 2011 at 5:37 am

From above it's like a F-16 with a huge rear end :P


Roland October 22, 2011 at 5:46 pm

I guess with all this upgrades SK were pursuing, NK are still not move, simply because they knows the Chinese were in their back.


Michael October 22, 2011 at 9:34 pm

I think they could probably pull it off. Realistically, it wouldn't be up to the capabilities of the F-22 or the F-35, but I don't think that is their goal. I think they are trying to build something comparable to the F-15 Silent Eagle (ok, it probably won't have similar power to weight ratios though). Front the front, their design looks like it could be made to have a low radar cross section. They even have long angled air intake pathways, which significantly reduces reflection off the front turbine blades. I am assuming they will have non-metallic leading edges, similar to the F-117. No big secret, high-tech stuff there. Now, the rear turbine nozzles, on the other hand, are not low signature at all! And for the record, I am ignoring the fact that all of the armament is on external stores, another stealth no, no… It's possible they could put an internal weapons bay between the cockpit and the engines? Due to the way the design pictures are, it would only be stealthy when attacking?


blight October 23, 2011 at 8:56 am

As long as it has the range to deliver a bomb to Pyongyang and return…

Wonder if the United States keeps nuclear weapons in Seoul for this.


blight October 23, 2011 at 9:02 am

On a side note, what's everyone's opinion on their missile plans? Does the ROK make a number of indigenous missiles?

Other notes on F-15K: Larger parts and avionics imported for final assembly by Boeing in STL. Does this count as Korean-made?


STemplar October 23, 2011 at 6:27 pm

The US only stores nukes physically in Europe outside the US now, or so they say…

The SKoreans have a cruise missile variant but their ballistic missiles are limited to 300km range and 50kg payload.


STemplar October 23, 2011 at 8:15 pm



blight October 23, 2011 at 10:41 pm

They also keep them in aircraft carriers, but adopt Israeli-style nuclear ambiguity about it.

I'm sure they don't keep them in Japan, especially since some things are hard to keep secret, and keeping something like /that/ secret would totally blow away Japan's and the United State's working military relationship.


Robert A. Fritts October 24, 2011 at 3:53 am

Does not look as good as the Japanese Stealth Projects Model that came out last year. The Mitsubishi model looked very well finished. Dont know if they have continued on it. Still love the New Kawasaki P-2 and KC-2, awesome.


F35 Insane October 24, 2011 at 8:53 am

We need to put DoD in charge and stop this progress immediately!


Stratege October 25, 2011 at 6:37 am

What is "Russian copy cat method". PAK-FA is not near where copy of anything,
S.Korean KF-X on paper does not look like a clone of F-22 too.


roland October 21, 2011 at 6:24 pm

I agree. Hope they (Norks and Chicons) are thinking the same thing.


crackedlenses October 21, 2011 at 6:57 pm

Arjun is a decent tank, just badly overbudget…..


roland October 21, 2011 at 7:27 pm

Or they could build it or buy it from us in secrecy for their self defense against an attacking force in the future.


roland October 21, 2011 at 7:44 pm

South Korea is also looking at buying 40 to 60 Sukhoi PAK FAs, F-35s or F-15SE Silent Eagles under its F-X program


crackedlenses October 21, 2011 at 6:55 pm

Weight, perhaps? My understanding is that the F-16 was a product of the light-weight mafia….


mike j October 21, 2011 at 9:41 pm

LOL… Whatever you do, DON'T say the thing that it is! Going to have to disappoint you, sorry.

Col. John Boyd was the leader of the "fighter mafia." He was fond of saying "You pay for airplanes like you pay for potatoes, by the pound!" Two engines _might_ halve the chances that you lose the plane to engine failure, but it doubles the chances of engine trouble. It adds weight and complexity that must be compensated for, and ultimately must be paid for. I said 'might' because you can have a situation like an engine fire that destroys the plane before you can recover it.

The point of the light weight fighter was an exceedingly inexpensive airframe that was nonetheless more advanced in every way that mattered to the air-to-air fight, as the fighter mafia saw it. The airplane they conceived of was not the one we purchased with the F-16. Some will say that was for the best.


PMI October 21, 2011 at 9:59 pm

It's utterly a copy of a Chinese model that looks copied from the Raptor minus vectoring nozzles? Think the middle man in that chain might just be the imagination of sino fan boys?


PMI October 21, 2011 at 11:35 pm

@brian: What's the tradeoff? What's the benefit of one engine over two?
— Fuel efficiency, weight & yes like it or not cost. Not only in the airframe itself but in the entire logistics chain. Only needing to support half as many engines in a fleet is a hell of a lot cheaper.

ABC news non-withstanding the Viper hasn't been referred to as the lawn dart since the early 80's. Also only half of those 18 Class A mishaps in '99 were engine related. The F-16 fleet has averaged roughly 2 engine related Class A's per year over the past decade or so.

@mike: "Some will say that was for the best."

—Yes radars really are good things to have! :D


Hurrah October 22, 2011 at 12:27 pm

Doofus, you do actually believe they can survive outside that umbrella?

Obviously from the anti-US perspective an alliance with the PRC or Pakistan or god knows which awful military junta run country would be better.

It never ceases to amaze me that those who see the US as all-evil will get with these strange bed-fellows. Of course, PRC, Iran, Pakistan, Russia, are all countries with much better records on virtually every issue.



mike j October 22, 2011 at 1:15 pm

re:"Yes radars really are good things to have! :D"

Well yes… but. It was really a practical consideration that made the fighter mafia dump the radar to begin with. BVR engagements had pretty well proven to be fictional at the time they were designing the LWF. If the fight's going to end up in the merge anyway, better to just leave all the expensive black boxes and antennas on the ground or in an AWACS. It's clutter at that point; extra pounds, extra drag, extra inertia to overcome.

I think what's interesting now is that the advances in passive systems might make it viable to leave an active array off a future fighter. Does every kind of platform need to have one of its very own -whatever-? A few weeks back there was a story about AT-6Bs doing air sovereignty intercept tests v. slow targets, and they were receiving all of their cues offboard via datalink. Something to consider.

(sorry for going off topic)


blight October 23, 2011 at 10:44 pm

What aerospace industry? Asides from the Skunk Works out in Palmdale Plant 42 (which is government owned contractor operated) I imagine security would have to be good. Background checks and the like, and evil union laborers, not your undocumented workers turning in bounties on design draft documents for dollars a page.

Why steal from the trash when you can bribe an Indian engineer (as what happened with the B-2 design). Funny how we think foreign nations steal from our trash as if they were inferior servants or carrion dogs, when they have the money to buy our secrets.


Thomas L. Nielsen October 24, 2011 at 3:03 am

'Scuse me, but is there any reason to believe any of that drivel?

It appears to me to be the height of arrogance to go "Stealth fighter? Then they MUST HAVE BEEN stealing our (US) secrets!".

There are plenty of smart people outside the US.

Regards & all,

Thomas L. Nielsen


PMI October 24, 2011 at 2:22 am

I think it's more important to ask …if the ROK has managed to steal enough information to build a 'composite stealth fighter' why they are so desperately looking for foreign partners to help in development of KF-X, including ones from which they have presumably already stolen the necessary information.


blight October 24, 2011 at 2:39 am

The paranoid bunch will say "for the finishing touches". Easiest to reverse engineer complete aircraft than do a bunch of ground-up work, even with some design specs, or even in the best case, engineering samples.


Riceball October 24, 2011 at 12:52 pm

Not that I believe in the conspiracy theories but it's one thing to know how to do something but another entirely to be actually able to do so. Just because they got the plans doesn't mean they have the technical know how to actually carry them out.


dave October 24, 2011 at 4:31 am

If the Norks ever attacked the RoK, there would be a lot of civ casualties in the South, but quality would tell. RoK would be on the Yalu within 6 months, having liberated millions of their starving brethren in the meantime. You might argue that the PRC would come in, but what the hell for? It's not 1951 any more.


tiger October 24, 2011 at 7:43 am

They all ready did? Did you miss the news about sinking of the Cheonan last May? The bombardment of Yeonpyeong last November?


Dfens October 24, 2011 at 3:05 pm

True, Australia does have plenty to complain about as a customer, but they are more than that. They are a soveriegn nation. They have a responsibility to themselves and to subsequent generations to be able to defend their country. All they are doing in whining. They aren't actually doing anything. South Korea, on the other hand, has seen what's going on and is doing something about it even if it's not exactly impressive. Perhaps future iterations of this design will be better. There seem to be at least 2 designs shown in the pictures above, with the latter pictures looking better than the first 2.


DODAVATAR October 24, 2011 at 3:46 pm

We caught the S. Korean "agents", actually Korean nationals working for the "Honeland"! Many countries do this, Israel had their "students" who volunteered to assist college professors who were conducting research on U.S. Department of Defense concepts (before they were accepted and became classified). Sadly, the FBI SAC and another agent were corrupted by an affair with an Asian (Chinese agent) beauty and failed to act on many many referred cases.


DODAVATAR October 24, 2011 at 3:51 pm

Like most countries "friendly" to the U.S. there huge intelligence gathering efforts by these countries to obtain information, not necessarily critical technology, but piecemeal with "pieces of the puzzle" that eventually creates much of the prize. It may be just the frequency of the avionic package or even the source of parts used in the package. Asians have more patience and can gather gobs of data collected by sympathetic (U.S. citizen immigrants).


mike j October 24, 2011 at 4:05 pm

Apart from showing off your bigotry, what's your point? Everyone spies on everyone else. So what?


melcyna October 24, 2011 at 9:16 pm

Well if you put it that way, i guess you have a point…

but to slightly help aussie here, they had a new government in charge after the federal election and given the political pressure (the F35 increasing cost and concern was most likely used as a weapon to poke at the government as well) they had to do something to appease the public as well.

They are not exactly concerned that someone might invade them or exert strong arm in any foreseeable future nearby, but there were a lot of attention and concern voiced on F35 cost and performance so even if it was a show, one can understand why they did it… they are stuck in a rock and a hard place, they can't turn around since that would have serious repercussion with other F35 project participant (aussie is level 3) and also in their relationship with US but they have to show to their people that they are trying to do something about it.

South Korea on the other hand are not participant to the F35 project, and more to the point, they actually have a real threat looming just across their border, plus they actually have a functional local weapon industry. So they are not tied politically, and have a real need to have functional weapon in hand, plus the infrastructure to build it.


blight October 25, 2011 at 9:36 pm

Then the onus is on the professors doing research to have their students background checked if they're working on military projects, now isn't it? Especially if they're funded by grants from DoD and need to list all their employees and volunteers on the grant application. And this is before they enter classified need-to-know land.

Any specific names and cases?


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