KAI KF-21 Boramae
After the United States, Russia and China, South Korea was the fourth nation to develop a (nearly) fifth generation fighter with stealth technology. It is called KF-21 Boramae, and developed by Korean Aerospace Industries (KAI). Given the desire to minimise radar reflections, the external shape of the KF-21 is quite similar to that of contemporary airplanes. It has slightly cropped delta wings with leading edge root extensions over the wedge shaped air intakes. The entire front fuselage has a distinctive body line from the wings to the tip of the nose. The canopy looks like that of the F-35: mostly popping out, but the back is covered. At the back are outward canted vertical stabilisers, not swept and with a trapezium shape. In between are two closely spaced jet engines with round exhausts. The main gear is attached to the side of the fuselage, below the wings, and retracts forward. The nose gear is retracted rearward. It has a single gear door on the left side.
Six prototypes were built, of which two are two seaters with a tandem canopy. So far, it has no dedicated designation.
Like similar stealth fighters the KF-21 has a distinctive body line across the middle of the front fuselage. This photo also gives a good view on the single nose gear door and forward retracting main gear. (photo: Wikimedia)
Already in the prototype phase there are tandem seat versions of the KF-21. Note the shape of the vertical stabilisers and round exhausts. (photo: DAPA/Wikimedia)
How to recognise the different versions of the KF-21
The different versions of the KF-21 can be distinguished by looking at the shape of the canopy. There are no different designations yet though.
Similar aircraft
Some airplanes look so similar to the KF-21 that you may confuse them. Below you can read how to distinguish them.
Differences KF-21 & F-22 Raptor
Externally, the KF-21 is almost a copy of the F-22, although it is less capable. The main external difference is that the exhausts of the F-22 are rectangular. Furthermore, the canopy and nose have a slightly different shape. Also, the gear retracts differently: on the F-22 outward for the main gear and forward for the nose gear.
Differences KF-21 & FC-31/J-35
The Shenyang FC-31 & J-35 are also quite similar to the KF-21. Both have delta wings, round exhausts and outward canted trapezoid vertical stabiliser. The FC-31 has a large, single nose gear door as a key feature. Additionally, the air intakes of the Chinese fighters are facing inward, like on the the F-35. The J-35 has swept vertical fins with cutoff top rear corners and a forward opening canopy. (photo: wc/WikiMedia)
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Differences KF-21 & F-35 Lightning II
While similar to the KF-21 in some ways the F-35 Lightning II there are significant differences with the KF-21. Firstly, the F-35 has one engine, fed from inward facing air intakes. Moreover, the two vertical stabilisers are swept. Finally, the nose is shorter.
Differences KF-21 & Su-57
The Su-57 is the Russian counterpart of the KF-21. As the stealth technology more or less dictates the shape, the Su-57 and KF-21 are look-a-likes. The best ways to keep them apart are the large space between the engines and nearly triangular vertical stabilisers on the Sukhoi.
Differences KF-21 & TAI Kaan
The last in the category 'fifth generation stealth fighters' is the TAI Kaan, that also looks similar to the KF-21. Its air intakes are more forward than on the KF-21, below the canopy. Moreover, the swept vertical stabilisers are on top of the engines. The main gear is attached to the underside of the fuselage.