This new variant of the prodigious Flanker family made its first flight on 29 April 1999 from the airfield of Zhukovsky near Moscow.

Apparently designed to remedy the shortfall in carrier-qualified pilots of the single-seat carrier-borne Su-27K (also known as the Su-33) Flanker-D, the Su-27KUB (Korabelny Uchebno Boevoy – Shipborne Combat Trainer) features the same side-by-side cockpit as the Su-34 strike aircraft grafted onto the fuselage of the naval Su-27K.

As well as the more obvious cockpit, the Su-27KUB also has a new, bigger wing with span increased to 16.00 m. The new wing also has the wing fold line moved further outboard which results in the folded portion adopting a more vertical position when folded – although there have been no pictures yet published showing this feature. The wing also has what Sukhoi publicity called ‘adaptive leading edge flaps’. This refers to the slats which have some sort of flexible cover, so that when they are deployed, there is no gap between them and the wing leading edge. Again, I have yet to see a picture of this feature.

With the wing fold moved outboard, the horizontal tailplanes do not need to fold, so this feature has been deleted – but the tailplanes have been increased in area.

Also increased in area are the two rudders – although the fins are the ‘standard’ size. New, bigger canards are also fitted.

The first prototype has been flying – first from Zhukovsky and now from the naval base at Saki in the Ukraine, where it has been making carrier takeoffs and landings using the ski-jump ramp and arrestor wires that are fitted to a mock-up section of the runway that represents the carrier Kuznetsov.

The colour scheme is unusual – the centre fuselage is camouflaged in the blues and greys of a standard naval Su-27K, but the new parts – wings, taiplanes, canards and rudders are in etched chromate or zinc primer. I assume that it will be fully painted in some sort of naval scheme at some point.

Although intended as a naval carrier-landing trainer, there is some speculation in the western press that, given the conical nose radome, it could be turned into a naval strike aircraft to accompany the ‘fighter’ Su-27K in a Kuznetsov-based airwing.

As soon as I saw the first published pictures, I wanted to make a model of this new variant to go with my other Flanker models, but the pictures were only side-views, none of them showed the new wing. During a trip to the MAKS 99 airshow at Zhukovsky, I purchased the new Su-27 Flanker book by Andrei Fomin. Although in Russian, this book is a must for Flanker Freaks, with loads of photographs, sketches, diagrams and colour profiles. It is so up-to-date that it has all the so-far published photographs of the Su-27KUB, but best of all, a plan view showing the differences between the KUB and a standard Su-27K. Not a scale drawing – but enough information with which to start on a model.

Armed with the plan view, I modified some Su-27K drawings that I have to include the revisions I needed – new cockpit, new wings and tailplanes, new canards and bigger rudders.

As in all of my Flanker conversions, I use the Airfix Su-27 Flanker as I consider it to be the most accurate of all the 1:72 scale kits currently available. It is also the worst of the bunch when it comes to fit ! Starting at the front, the most obvious donor for the new side-by-side cockpit is the Italeri Su-34 kit. Unlike Sukhoi, who at least had a common airframe to start with, I had to combine two kits from different manufacturers, with all the attendant mis-matches in profile shape etc. The Italeri two-seat cockpit fits onto the Airfix single-seater – but only just !!

I can’t tell you where to make the saw cuts – I did it by trial and error, but I would recommend using the smallest section of the Italeri cockpit that you can get away with – the sill and windscreen decking being the most important. The removed cockpit section was test fitted to the Airfix kit and a similar section was removed from the single seater. There is a huge mis-match between the two, but by careful cutting and testing, you can get the Italeri cockpit section to perch on the Airfix fuselage. The biggest problem is the cockpit interior – the tub is too wide at the bottom to fit inside the Airfix fuselage. I had to carefully pare away the side consoles until it just sat inside the Airfix contours. I also had to shave away the plastic on the ouside of the Italeri cockpit section to get it to fit – the Su-27KUB retains the chine of the single seater all the way to the conical nosecone – unlike the Platypus-beaked Su-34.

The accompanying photographs show the surgery involved. With the benefit of hindsight, I think the cockpit on my model sits too low at the rear. It should have a bigger ‘hump’ with the lower side sills sloping down from tail to nose. Maybe I will get it right on my next model !

The new cockpit blends into the existing spine just in front of the dorsal airbrake – there is no large fairing as on the Su-34, just a sharply-raked smaller fairing that gives the Su-27KUB a distinct hump-backed appearance. I used scraps of plastic card added to the spine behind the new cockpit to build up the fairing . Later, I blended the whole lot in with copious amounts of Milliput shaped as close as possible with a wet finger before the Milliput hardened.

The new, bigger canards are mounted on large ‘shoulders’ that extend forward from the wing leading edge. These are made in a similar way to my Su-37 & Su-27K articles – large crescent shaped pieces of plastic card later bended in with Milliput.

  The new canards were made from the tailplanes of the Italeri Su-34 kit and added later.

Like its single-seat progenitor, the Su-27KUB has a revised tailboom that is shortened and raised above the centreline to avoid tailscrapes. Using the same method as on the Su-27K model, I cut away the existing tailboom and carved an 8mm dia. plastic knitting needle to shape before cementing it in place a blending it in with filler.

 Note that the naval Flanker does not have the prominent chaff/flare boxes of its land-based cousin – it just has thin fairings reminiscent of the early production Su-27.

The wings on the Su-27KUB have a greater span and revised wing fold. To represent this I used a combination of the wing roots from the Airfix wings to which were added the complete wings from the Italeri kit.

As a start I removed the outer sections from the lower Airfix wings – 30mm from the tip, leaving enough of a tab to fit into the corresponding slot in the Italeri wing plus 9mm .

A 9mm section was removed from the roots Airfix wings, 

which when combined with the Italeri wing gave a wing of the necessary increased span. The Italeri wings have a small tab at the root where the flap is. This was removed to provide a straight wing root to butt against the Airfix wing root. 

In order to get the trailing edge of the Italeri wing in the correct position, it is necessary to mount the wing slightly forward at the leading edge. This results in a mis-match at the front and a gap at the rear that were made good by sanding the leading edge back and adding plastic card to the trailing edge root 

At this point we now have a wing of the correct span and area and it is important to hide the joints and the old control surfaces completely with filler.

The new flap, slat and wing fold lines (38mm from the wingtip) were scribed on and the new wing sanded smooth.

 Considerable amounts of filler and plastic card plugs are required to blend in the wing undersides.

The Airfix rudders were cut away and new ones made from the Italeri tailplanes were added.

 The new rudder trailing edge is vertical in side view and meets the tailplane actuator further to the rear.

The new, bigger, tailplanes were cut to shape from the Italeri fins,

 sanded to a profile section and added to the mounting booms with a plastic rod pivot for strength. New, bigger, actuator covers were carved from plastic card and cemented in place.

With all the major components in place, the model was washed in warm soapy water to remove all the sanding debris and when dry, it was given a coat of grey primer to highlight any flaws. Once these were made good, final painting could begin. One thing that does need adding is the cannon barrel in the starboard wing root. This had been lost when the canards were added, so a new one was fashioned with a drill and sprue using an original kit as a guide.

The only pictures of the prototype Su-27KUB published so far show it in an interesting mix of blue/grey camouflage (presumably from a donor Su-27K airframe) and yellow primer.. The yellow primer is Humbrol 81 lightened with lots of white sprayed onto the wings, forward fuselage, taiplanes and rudders. I also undercoated the fins in primer.

The blue/grey camouflage pattern was airbrushed onto the centre upper fuselage, fins and underside engine nacelles.

Dark grey was used on the flaps and a section of wing just behind the slats. These are presumably the ‘adaptive wing’ flexible portions that fill the gap when the slats are deployed.

The rest of the airfame was ‘dirtied up’ with various mixes of darker yellows, squares of painted decal film. The fins in particular show signs of heavy paint flaking so the blue-grey camouflage was rubbed with a sanding block to reveal areas of primer underneath.

The nosecone is white and the dielectric panels on both fin tips and the leading edge of the starboard fin plus the fronts of the wingtip launch rails are dark grey.

The undercarriage comprises Airfix main legs and wheels plus the upper part of the Airfix noseleg married to a scratchbuilt lower section with the twinwheels from the Italeri kit. To be 100% accurate, the mainwheel legs should be thicker – they are ‘beefed’ up from their land-based counterparts – and the fairing behind that contains the locking pins should be bigger.

Final detailing comprises the addition of the IRST ball in front of the windscreen from clear sprue, an arrestor hook fashioned from square-section sprue, the retracted refuelling boom from the Italeri kit and the aerials, air dat probes and undercarriage doors from the Airfix kit. The two retracted lights used during aerial refuelling are represented by blue-painted circles of decal from the spares box. Here are the finished results:

This model is probably not totally accurate – there are no published drawings that I have yet seen. I based it on plans of the new wing shape and published photographs – but it is as near as I can get at this early stage of the aircrafts flight development. Anyway, by the time I do see a set of plans, the prototype will have been painted and had markings added – so I will have to make another one anyway – this time with the wings folded !

Ken Duffey January 2000