KAI KF-21 Boramae (KFX Korean Indigenous Fighter program)

[VTOLicious]

Whatever the recess holes are for. I was referring to the grid structure beneath.

 

[robunos]

D'oh !!
I think that the difference in the grid pattern is to accommodate the difference in the stress / load patterns caused by the presence of the apertures. Compare the difference in the grid patterns in the image below . . . it's the same component . . .

cheers,
Robin.

 

[TomcatViP]

Exactly. That's why I was pointing to what I believe is the opening for the gun

 

[robunos]

In fact, I wouldn't be surprised if all this isn't done for you in the design software. Input size, outer mould line, what cut-outs you want, and where, what material to use, then plug in the predicted loads and stresses for the component, and the software lays out the optimum stiffener grid pattern and thicknesses, as a CAD/CAM file, ready for your CNC machine tools . . .

cheers,
Robin.

 

[Grey Havoc]

In fact, I wouldn't be surprised if all this isn't done for you in the design software. Input size, outer mould line, what cut-outs you want, and where, what material to use, then plug in the predicted loads and stresses for the component, and the software lays out the optimum stiffener grid pattern and thicknesses, as a CAD/CAM file, ready for your CNC machine tools . . .

cheers,
Robin.

There have been a number of attempts at that over the years. They've never quite worked out in practice though...

 

[litzj]

I saw some images of bulkhead structure of prototype.

Yes, ... but almost one year old already.

View attachment 627724

I just noticed that the left / right supporting struts are different. Might be just a test specimen... However, I don't know what the korean text says.

Korean words mean ceremony of KAI for the first bulkhead-production; meaningless for engineering aspect

There are many asymmetries mainly because of LRU, hydraulic system, electrics...
Gun will be located at upper fuselage, and it will not make significant asymmetry in bottom of the bulkhead.

 

[Mach42]

Gun?

If you are wondering, the roughly trapezoid-shaped cutout on the port side of the aircraft is indeed for the gun. Click through the following link:

쉘든의 밀리터리 : 네이버 블로그

blog.naver.com

 

[TomcatViP]

Thank you. Case closed it seems.

 

[Deino]

https://twitter.com/x/status/1238093689618079746

 

[stealthflanker]

On The KFX Radar Development

[단독] 말 많던 'KF-X 레이더' 감사했더니…"상응 조치 미흡"

저희가 단독 취재한 내용 하나 더 전해 드립니다. 첨단 한국형 전투기 개발, KF-X 사업이 한창인데, 이 사업의 성패는 'KF-X의 눈'이라고 할 수 있는 다기능 위상배열 'AESA 레이더'를 독자 개발하는 데 달려있습니다.

news.sbs.co.kr

The news reports that there are increase of development cost from 168 B Korean Won in 2016 to 213.4 B in 2019 and expected to increase more. The news reporter also argues about the performance of the prototype radar which does not correspond to what was promised.

----------
I think it's worth the effort to solve and iron out the problem as it will provide South Korea to the true ability to make AESA fighter radar, make it scalable then they basically can develop everything out of it.

 

[GARGEAN]

Any details on radar itself?

 

[stealthflanker]

Any details on radar itself?

Rather few but based on this interview :

Translation however is done by KR Military fanpage in facebook, some point being :

- Prototype KF-X AESA radar had around 1,088 Transmitter-Receiver Module (TRM). By 2023, the number is expected to increase by 20% to have around 1,200~1,300 modules. (F-22's radar has 2,000 and F-35's radar has 1,200)

- Maximum detection range is said to be around 200 km (unknown against which-sized target)

The full link to the translated version.

 

[stealthflanker]

For emitted power prediction however one could perhaps guess from this image :

This depict the antenna parts, from left to right :
-AESA antenna
-Power Supply
-Cooling Unit for the Antenna
-Antenna testing equipment.

The part of interest would be cooling unit which denotes 7.7 KW of cooling capacity. This directly impacts the amount of average power that can be emitted by the antenna.

With following assumption which typical for AESA TRM :

PAE of 33% (A Class module for linearity)
3 cm wavelength (0.03 m)
and 1088 as antenna element module

One can predict the average power limit which is about 1857 Watt. Assuming 25% duty cycle the peak power of the radar would be about 7.4 KW. Each module would then be having about 6.8 Watt of peak power and 1.7 Watt of Average power at 25% duty cycle. Other duty cycle is possible (e.g 10%) But the average emitted power can never exceed that 1.857 Watt without additional cooling capacity.

At that duty cycle and assuming 0.03 seconds of dwell time per beam, range can then be predicted to be about 181 Km for 3 Sqm target with detection probability of 90%. The variants with 1300 Modules can therefore reach about 220 Km against target of same RCS.

 

[Deino]

Not sure, how reliable this site is but the artworks - including a twin seater I did not know before - are the best I've seen so far:

한국항공우주산업 블로그 : 네이버 블로그

blog.naver.com

 

[stealthflanker]

I would say it's the official artwork of the KF/X itself. made by the KAI. You can compare with the one in their website :

KAI KOREA AEROSPACE INDUSTRIES, LTD.

 

[helmutkohl]

GE Delivers F414 engines to KAI which will soon install them on the KFX

I guess the airframe is done?

GE Aviation delivers first F414 engine to South Korea for KF-X program | GE Aerospace News

LYNN, Mass. – GE Aviation delivered the first F414-GE-400K engine in May to Korea Aerospace Industries Ltd (KAI) for South Korea’s next-generation indigenous fighter, known as the KF-X. Developed for the Republic of Korea Air Force (ROKAF), the F414-powered KF-X will deliver significantly...

www.geaviation.com

 

[totoro]

Are there any articles that mention Lockheed Martin aid or involvement of any kind (even if small) when it comes to actual research and development of the layout/airframe concept/systems subsystems integration for the KFX?

 

[helmutkohl]

Are there any articles that mention Lockheed Martin aid or involvement of any kind (even if small) when it comes to actual research and development of the layout/airframe concept/systems subsystems integration for the KFX?

Yeah they are partners and I believe Korea buying the F-35, resulted in Locky agreeing to give 2 dozen tech transfers of the F-35 for use in the KFX.

Its interesting since the KFX and the Chinese JF-31 both look like they could be what the F-35 was had it been twin engined.
the main difference is one is powered by the F414 and the other by RD-93s
asian cousins that might lock horns one day.

 

[helmutkohl]

almost done!
assembly to be complete this year

KAI to finalize assembly of next-gen KF-X fighter jet in H2

Korea Aerospace Industries said Wednesday it will finalize the assembly of its next-generation KF-X fighter jet in the second half of this year. South Korea’s sole aircraft manufacturer is currently assembling each of the top, middle and bottom parts of the fuselage of its fifth-generation...

www.koreaherald.com

 

[VTOLicious]

Not sure, how reliable this site is but the artworks - including a twin seater I did not know before - are the best I've seen so far:

한국항공우주산업 블로그 : 네이버 블로그

blog.naver.com

View attachment 631512View attachment 631513

Looking at those pics... Is it reasonable to say that KFX is based on the concept of the F-22A, but with relaxed stealth / agility (no internal weapons, no TVC), scaled down to a size similar to the F-35, but with better performance to be expected (2x F414, no VSTOL derivative)?

 

[helmutkohl]

Not sure, how reliable this site is but the artworks - including a twin seater I did not know before - are the best I've seen so far:

한국항공우주산업 블로그 : 네이버 블로그

blog.naver.com

View attachment 631512View attachment 631513

Looking at those pics... Is it reasonable to say that KFX is based on the concept of the F-22A, but with relaxed stealth / agility (no internal weapons, no TVC), scaled down to a size similar to the F-35, but with better performance to be expected (2x F414, no VSTOL derivative)?

It will have a weapons bay.
if you look at the first fueselage cut out a page back, you can see the provisional space for it

basically their plan is
block 1. semi recessed bay, a2a
block 2. a2g
block 3. internal weapons bay and full stealthy avionics suit

my question is.. why don't they include the full weapons bay from block 1?
are they that in a rush to get it out?

 

[TomcatViP]

It's probably linked to the lack of a full RCS treatment on the KFX Mk1. Instead of pouring money that won't get put in use, It sounds more reasonable to phase in the complexity of having a WB (think structural and separation testing) only when the airframe gets the appropriate level of Stealth.
In the meantime, they can work validating the airframe, systems and understanding its real structural behavior etc...

 

[Sundog]

Also, it might be that that space will be used for fuel in the block 1 and block 2, giving them longer range on internal fuel alone, as well.

 

[TomcatViP]

Range is less critical in the Korean peninsula.
But obviously, that space won't be left empty and fuel tank would make a great usage of it.

 

[Deino]

Still no new images?

 

[stealthflanker]

Not yet unless you want bunch of CGI's XD

 

[Deino]

Not yet unless you want bunch of CGI's XD

No, I only want the real deal!

 

[Mach42]

Are there any articles that mention Lockheed Martin aid or involvement of any kind (even if small) when it comes to actual research and development of the layout/airframe concept/systems subsystems integration for the KFX?

No direct tech involvement. LM engineers are working in an advisory role. This is just a single example but there have been continuous job listenings with basically the same template for every aspect of modern fighter design, use google and look for yourself:

Aerodynamic Performance Analysis Engineer, KF-X Program at Lockheed Martin Corporation

We are hiring for Aerodynamic Performance Analysis Engineer, KF-X Program in Fort Worth. Lockheed Martin. Your Mission is Ours.

www.lockheedmartinjobs.com

Not sure, how reliable this site is but the artworks - including a twin seater I did not know before - are the best I've seen so far:

한국항공우주산업 블로그 : 네이버 블로그

blog.naver.com

View attachment 631512View attachment 631513

Looking at those pics... Is it reasonable to say that KFX is based on the concept of the F-22A, but with relaxed stealth / agility (no internal weapons, no TVC), scaled down to a size similar to the F-35, but with better performance to be expected (2x F414, no VSTOL derivative)?

Look at this blog and you can see the KF-X was based on the F-35A in the beginning. It had F-35A dimensions and F-35 aerodynamic surfaces like a 460ft^2 wing area. Then aero optimisations caused things like the vertical stabilisers to become more F-22A like. https://blog.naver.com/jhst3103/221484299260

Not sure, how reliable this site is but the artworks - including a twin seater I did not know before - are the best I've seen so far:

한국항공우주산업 블로그 : 네이버 블로그

blog.naver.com

View attachment 631512View attachment 631513

Looking at those pics... Is it reasonable to say that KFX is based on the concept of the F-22A, but with relaxed stealth / agility (no internal weapons, no TVC), scaled down to a size similar to the F-35, but with better performance to be expected (2x F414, no VSTOL derivative)?

It will have a weapons bay.
if you look at the first fueselage cut out a page back, you can see the provisional space for it

basically their plan is
block 1. semi recessed bay, a2a
block 2. a2g
block 3. internal weapons bay and full stealthy avionics suit

my question is.. why don't they include the full weapons bay from block 1?
are they that in a rush to get it out?

That is fan art. There has been preliminary research on an IWB that will fit 4 AMRAAMs or 2 AMRAAMs and 2 SDBs. No concrete plans to actually produce such version (notional Block 3) yet, however.

Range is less critical in the Korean peninsula.
But obviously, that space won't be left empty and fuel tank would make a great usage of it.

I probably won't hold fuel. This is why the KF-X won't have the legs of the similar size and identical engined Super Hornet. But ROKAF considers the KF-X to be in the same class as the F-16 so KF-X's range meets the ROC.

Not yet unless you want bunch of CGI's XD

No, I only want the real deal!

Probably won't be much until the roll-out next year, or at least don't hold your breath. Maybe if we are fortunate there will be an in-progress picture before that but so far KAI hasn't done a lot of PR.

 

[helmutkohl]

^ what makes you think its fan art? (serious question because I also want to know of its authenticity)
found it here

KJCLUB - KFX

as for block 3 having a full weapons bay
it has been reported on various defense news sites

KF-X Fighter: Koreas Future Homegrown Jet

South Korea has been thinking seriously about designing its own fighter jet since 2008. The ROK defense sector has made impressive progress, and has become a notable exporter of aerospace, land, and naval equipment. The idea of a plane that helps

www.defenseindustrydaily.com

 

[Mach42]

^ what makes you think its fan art? (serious question because I also want to know of its authenticity)
found it here

KJCLUB - KFX

as for block 3 having a full weapons bay
it has been reported on various defense news sites

KF-X Fighter: Koreas Future Homegrown Jet

South Korea has been thinking seriously about designing its own fighter jet since 2008. The ROK defense sector has made impressive progress, and has become a notable exporter of aerospace, land, and naval equipment. The idea of a plane that helps

www.defenseindustrydaily.com

It was a submission in KAI's regular competition for aerospace research papers. It's called "항공우주논문상 공모전" and happens yearly. Here is the origin of the paper from 2013: http://bemil.chosun.com/nbrd/bbs/view.html?b_bbs_id=10040&pn=1&num=74395

And I'm not denying that a Block 3 exists, I'm just saying it isn't an official and sanctioned plan that has any funding and is more of a proposal from the company. Block 1 and Block 2 ideas pretty much line up with being IOC and FOC versions, while Block 3 is more of a future improved variant.

 

[helmutkohl]

AESA radar for KFX to be delivered next month!

Hanwha ready to ship first AESA radar for KF-X - Alert 5

South Korea is reported to have completed the first AESA radar to be tested on the KF-X fighter. The radar will be delivered to the customer next month. Press reports from the country says the radar was tested in Israel and earned praise from the Israelis for its performance. It has been...

alert5.com

so we got the engines and radar down!

 

[stealthflanker]

It starts to take shape.

 

[Deino]

It starts to take shape.

Thanks ... and what does it say?

 

[Sundog]

At this point, is this an all Korean project? Has Indonesia provided the funds that were supposed to be allocated at the beginning?

 

[Mach42]

It starts to take shape.

Thanks ... and what does it say?

With the KF-X Project Director, the Director of Operations, and other officials involved in KF-X's development in attendance, the company (KAI) held a ceremony in the main assembly hall on the 23rd of April, that celebrated the start of the assemble of the forward, centre, and rear fuselage sections. This signifies the final step of assembly in the development path of the KF-X prototype. What was only seen till now on the screen as a CATIA model now could be seen in person and its size, the speed of completion, and KAI's high level of technology could be appreciated. Everyone pledged to do their utmost to finish within the deadline of the April 2021 rollout.

A lot of fluff basically, no special details.

At this point, is this an all Korean project? Has Indonesia provided the funds that were supposed to be allocated at the beginning?

The PT DI engineers that were working at KAI have left due to Coronavirus and the fact that their wages were supposed to be paid with the money from Indonesia. The latest news is that payment is still delayed and negotiations between the two sides are still ongoing.

 

[helmutkohl]

The PT DI engineers that were working at KAI have left due to Coronavirus and the fact that their wages were supposed to be paid with the money from Indonesia. The latest news is that payment is still delayed and negotiations between the two sides are still ongoing.

I wonder how many Indonesia will order
based on their past history of acquisitions..
perhaps they will buy 10 KFXs
then later, 5 F-35s
and then 5 Su-57s
and no missiles for any of them.

 

[stealthflanker]

I wonder how many Indonesia will order
based on their past history of acquisitions..
perhaps they will buy 10 KFXs
then later, 5 F-35s
and then 5 Su-57s
and no missiles for any of them.

Well there were also 40+ Hawk order too in the past.

I would love if the orders remain at 48 as it was in plan. Therefore good for both side. Any reduction in the amount of order will directly impact the price of each aircraft, if Indonesia ever cancel or reduce the amount of builds... It will increase the price of the plane and that wont go well for the Korean.

Missiles is yes as they are of a separate contract. e.g we received our BVR Missiles for our Flankers in like 5-6 years after the first Su-27 and Su-30 arrived.

 

[helmutkohl]

I wonder how many Indonesia will order
based on their past history of acquisitions..
perhaps they will buy 10 KFXs
then later, 5 F-35s
and then 5 Su-57s
and no missiles for any of them.

Well there were also 40+ Hawk order too in the past.

I would love if the orders remain at 48 as it was in plan. Therefore good for both side. Any reduction in the amount of order will directly impact the price of each aircraft, if Indonesia ever cancel or reduce the amount of builds... It will increase the price of the plane and that wont go well for the Korean.

Missiles is yes as they are of a separate contract. e.g we received our BVR Missiles for our Flankers in like 5-6 years after the first Su-27 and Su-30 arrived.

serious question.. why is Indonesian arms acquisition so unusual?
lots of small acquisitions of a variety of aircraft. Flankers of two different types, Vipers, golden eagles, hawks.. all in low numbers?

 

[stealthflanker]

serious question.. why is Indonesian arms acquisition so unusual?
lots of small acquisitions of a variety of aircraft. Flankers of two different types, Vipers, golden eagles, hawks.. all in low numbers?

Hawk is not in small numbers. So does the Vipers. It boils down to how you define low numbers actually.

The thing that makes our acquisition looks small is because of no consistency of procurement (change of regime, even change of high ranked officer in the service can affect procurement)

Also the timeframe. By the time we desire to procure more Su-27's. There is no more Su-27SK around unless one wish to draw VVS Stock.. so we stick with Su-27SKM. When we desire to procure more Su-30MKK, no more of such type being made but we ended up having the improved but high commonality Su-30MK2.

Ideally even in "small number" procurement for same type should continue but that was unfortunately not the case.

 

[Deino]

https://twitter.com/x/status/1280162730155139074