The following is an article I wrote for Scale Models magazine about how to scratch-build a Yakovlev Yak-141 Freestyle. It was published in the January 1993 issue of the magazine and I have scanned the text and photos from that issue - hence the poor quality of the photographs and drawings.
The real Yak-141 at Farnborough. Photo Gordon Millar.
First revealed to the western aviation press in the form of a video at the Paris Salon 1991, the first of two prototypes of the Yakovlev Yak-141 apparently made its maiden flight in March 1989 in the hands of test pilot Andrei Sinitsin. Allocated the NATO reporting name Freestyle, the aircraft is basically a larger and faster evolution of the Yak-38 Forger, which operated with the AVMF on the Kiev class anti-submarine carriers.
Like the Forger, the Freestyle has three engines - two mounted vertically
in the forward fuselage just behind the cockpit to provide vertical lift
and one mounted horizontally in the rear fuselage which provides both vertical
and horizontal thrust
Unlike the Forger, however, the main engine does not exhaust through swivelling bifurcated exhausts, but via a straight-through jetpipe, which is pivoted so that the thrust can be directed down. This method allows the main engine to be fitted with an afterburner, bestowing a supersonic performance of Mach 1.7— indeed the Freestyle is the world’s first supersonic V/STOL fighter, something the British aviation industry were near to achieving in the Hawker P-1154 which was cancelled in 1965.
The Yak-141 has broken a number of records already, including the Harrier’s time-to-height record for V/STOL aircraft. Whether the aircraft will enter service is in doubt following the disintegration of the Soviet Union and the subsequent withdrawal of funding. The Yakovlev design bureau were actively seeking foreign co-production and export customers — Spain and India being mentioned. However, the program suffered a further setback when one of the two prototypes crashed in November 1991. The aircraft was apparently making a test flights from a modified Kiev-class carrier, the Admiral Gorshkov, when it descended too rapidly on final approach, crashed into the deck and was destroyed in the ensuing fire. The pilot ejected safely.
I have enlarged and re-traced the existing three-view drawings making corrections where appropriate. I don’t claim that they are 100% accurate, but they are a combination of the best features of those published so far.
Provisional scale drawings. Span of real thing is 10.105m, Overall length 18.38m.
For a better set of drawings see Aerofax 'Yakovlev's V/STOL Fighters. (ISBN 1 85780 041 9)
Always on the look-out for the unusual — and particularly unusual Soviet
- aircraft, I was idly toying with the idea of scratch-building a Yak-141
and had scaled up the available general-arrangement drawings when the IPMS
Special Interest Group to which I belong, the Soviet Aircraft SIG, published
an article and drawings on the Freestyle and asked if anyone was contemplating
producing a model and if so, would it be ready for the IPMS Nationals in
Never one to shirk a challenge, I looked through my collection of kits to see if there was anything that vaguely matched the drawings that could be modified. I found one or two items, so what follows is a description of how I did it - fellow modellers may want to adopt a different approach and no doubt as soon as this article appears there will be an injection moulded kit available! In the meantime...
After casting around my kit collection for a suitable fuselage, I decided that the Hobbycraft kit of the two-seat Sukhoi Su-22 Fitter-E looked about the right diameter and shape at its rear end (the KP Su-7 could be substituted for the Hobbycraft kit). It was, of course, too wide at the front end, but this was remedied by first cutting off the fin and spine and then removing triangular sections from each fuselage half so that the width was reduced at the front end, (see Fig. 1).
The nose section of the Su-22 was also removed to bring the length to
that of the Yak-141 minus its radome. After lots of hacking, filing and
sanding the fuselage halves were cemented together to form a fuselage of
approximately the right dimensions with the rear cockpit opening of the
Su22 in the right place to form the Yak-141’s cockpit.
This opening was made wider by removing plastic from the sills and the former front cockpit of the Su-22 was filled in with scrap plastic and Milliput.
The nose radome came from the Reconnaissance pod supplied in the Matchbox Phantom kit. I used the UPPER halves of two pods cemented together and sawn off to the correct length. No doubt other spare radomes would do just as well — I just happened to have the recce pods in my spares box.
The radome was super-glued to the front of the modified fuselage and faired in with scrap plastic and filler. All the panel lines on the Su-22 fuselage were filled in and attention turned to the decking behind the cockpit Again a well-stocked attic came to the rescue in the shape of the old Heller SAAB AJ-37 Viggen kit. This comes in three versions and has different spines for each, so the spine for the two-seat trainer variant, the SK-37, was utilised, requiring only minimum modification to fit on the Su-22 fuselage. The spine was cemented in place and faired in at the rear to give a smooth top line when viewed from the side.
As an added complication, I wanted to show the Freestyle’s lift engines,
so I decided to use the parts from a spare Revell Yak-38 Forger kit. I
removed a section from the Viggen’s spine the same shape as the Forger’s
forward intake door and boxed in the resultant hole with plastic card.
The two lift engine faces from the same source were then added.
I also utilised the lift engine exhaust grilles from the Forger kit and cemented it in place in a cut-out in the bottom of the Yak-141 fuselage. Even more perverse was my decision to have the rear jetpipe rotated into the VTO mode with the cross-dam extended. There are, as yet, no published photographs showing how the jetpipe and doors work so I took my details from an article in Air International for August 1991. At this stage the rear fuselage was simply cut away on the underside to accept a jetpipe later.
Underside view of the finished model showing the lowered jetpipe with cross-dam in front of it.
With the fuselage gaps filled and the whole lot sanded smooth it was time to turn my attention to the intakes and side boxes. This time my kit collection let me down! I looked at all the kits that had wedge-shaped intakes from the Tornado to the F-15 and none were the right size or shape, so the only answer was to scratch-build them from plastic card, which proved easier than I had first thought.
I photocopied the main drawing and cut out the side, top and bottom shapes of the side ‘boxes’. These were then used as templates to create the faces of the boxes in plastic card. With rectangles of plastic card acting as bulkheads, the top and bottom pieces were carefully cemented in place on the outer faces. When thoroughly dry the three-sided box was offered up to the fuselage and sections were cut from the bulkheads so that the sides would fit snugly up against the fuselage — all very trial and error.
Once I was happy that I wasn’t going to get a better fit, I made the INNER faces of the box from plastic card, but this time only the front and rear ends. I also made the boundary layer splitter plate and attached it to the front inner face then cut holes for the main undercarriage bays and boxed in the insides, (see Fig.2). The rear ends of the ‘boxes’ are rounded in section so the extremities were removed and replaced with thicker plastic card laminations which were then carved and sanded to shape. The two side boxes were cemented in place and any gaps (and there were plenty) made good with scrap plastic card and filler.
The pen-nib fairings were built up from top and bottom sections, cut to shape from the main drawings, cemented to the inner faces of the boxes at the rear behind the jetpipe. The curved sections were made from thin plastic card, cut roughly to shape and bent to a curve before being cemented in place. Once the cement had dried the curved section was cut and sanded down to fit.
Rear pen-nib fairing.
Another raid on the spare kits collection provided the wings, this time from a Matchbox F-16 kit. With the wingtip missile rails removed and the trailing edge reshaped they are almost a perfect match. They are too short in span and require the addition of plastic card inner sections carved to the same aerofoil shape and Leading Edge Root Extensions (LERXs) made from plastic card cut and sanded to shape as per the drawings. The wingtip pods, which house the reaction control nozzles, were made from plastic card. Finally, the existing engraved panel lines on the F-16 wing were filled and new ones scribed on together with the outlines of the control surfaces.
F-16 wings - original at bottom, cut-down at top.
Fins and Tailplanes
The fins came from an old Airfix F-18 kit. They were simply cut down to shape and cemented on to dorsal strakes made from plastic card cut and sanded to shape. The horizontal stabilisers were made from plastic card cut to shape and sanded to an aerofoil section. A short length of Contrail rod was used to attach them to the fuselage.
As mentioned earlier, I wanted to show the aircraft in its VTO configuration despite the lack of firm data. Having already added the forward lift engines, they were painted and the intake door from the Yak-38 was cemented in place in the open position with two operating rams added from sprue. The cockpit was detailed and a white-metal Aeroclub KM-1 ejection seat added (this should be a K-36 seat but as there was not one available I modified the KM-1 to look like a K-36). The canopy came from the spares box —I don’t know the source but it was the right size and shape, I only had to add a little filler at its rear edge to get it to fit snugly against the spine.
I would have liked to show the canopy in the open position but I have yet to see a photograph showing which way it works, so in the meantime my canopy is firmly closed. Doors for the forward lift engine exhausts and the undercarriage were made from plastic card and cemented in place.
There are two lengthwise strakes along the bottom of the fuselage and there is some speculation that the port strake has a cannon muzzle at its front end. The strakes were shaped from plastic card and the muzzle came from Contrail tubing faired into the port strake. One of the prototypes is fitted with an avionics pod above the cruise engine exhaust (the other aircraft has what looks like the same sensor pod fitted to the rear extremity of the port tail boom). This pod was fashioned from a suitably sized bomb obtained from the spares box, cemented in place above the jetpipe.
With all the major components in place I gave the whole airframe a thorough wash in soapy water and when it was dry an overall coat of Halfords Grey Plastic Primer was sprayed on — after masking off the canopy and lift engines. Once I was happy with the overall appearance I was ready to continue.
The model was given a final spray coat of Grey Plastic Primer, which incidentally looks like a good match for the finish applied to the Yak-141, so it was left as the top coat! The fin tips were painted white and the radome Humbrol Panzer Grey to match the colour photographs in Air Forces Monthly for October 1991. This publication has photographs of both prototypes, Yellow 48— the subject of this article — and White 77 - which differs in having grey fin tips and a different avionics pod location.
With the paint dry I added the undercarriage and wing pylons from a Yak-38 Forger and the main engine exhaust nozzle made from a spare nozzle found in the spares box — again I don’t know what it originally came from but any exhaust of suitable diameter will suffice. It was cut down and cemented to two sections of tubing to form the swivelling nozzle, (see Fig.3). The whole assembly was cemented in place in the cut-away lower jetpipe. A cross-dam or deflector door made from plastic card was cemented to the fuselage underside just in front of the nozzle. Details of the above arrangement were obtained from the August 1991 issue of Air International, which has a short article on the Yak-141 together with speculative drawings of how the aircraft achieves VTO and STO.
Unfortunately there are no clear details of how the nozzle actually rotates and how the lower fuselage folds away to accommodate it, so my arrangement is pure conjecture. Decals came from the spares box and were applied after the model was given an overall coat of Johnson Wax Klear. A final coat of Klear sealed the decals in.
Finished model before update - see 'Addendum'.
So there you have it. It looks like a Yak-141 and is as accurate as the available data will allow — although in retrospect I am not too happy with the cockpit canopy, I have got the windscreen wrong so I might get round to changing it. With a little effort a reasonable replica has been produced and I am sure that fellow modellers could find a better way to reproduce the shape using different components —what you might call ‘Freestyle’ modelling!
The model was completed in time for the IPMS Nationals in November 1991 and was based on the then available data. The article was written and submitted for publication in the spring of 1992, since which time the subject has made an appearance at the Farnborough Air Show and more details have become available.
In the light of recently published photographs I decided to revise my
Yak-141 to bring it bang up to date....
The most serious inaccuracy lies in the lower forward fuselage which I had modelled as having a circular cross-section, whereas the published photographs of the Farnborough machine show a definite square section similar to the Tornado with a flat bottom surface and sides. To remedy this I removed the undercarriage and all the doors and rubbed down the fuselage underside from just behind the radome to the rear of the forward lift engine bay.
A rectangular piece of plastic card, tapering to a point at its front end and the same width as the fuselage in plan view, with cut-outs for the nose-wheel and lift engine bays, was then cemented into place to give a flat bottom surface. The fuselage sides below the canopy were then filled with Milliput to give flat vertical cockpit sides, the whole lot being blended into the radome and lower plastic card whilst still wet.
When all was dry it was rubbed down to give a square section with rounded corners blending into the circular radome — a glance at a Tornado will show the required shape. New wheel and lift engine bays were fabricated from plastic card and added.
Having been unhappy with my original canopy shape, I also took the opportunity to carve and plug-mould a new one. The windscreen was removed to allow the canopy to be cemented in the open position, a more detailed cockpit being fabricated at the same time using the newly available data. The open canopy also neatly gets round the problem of the fit of the home-made canopy!
The only other major revision is in the extremities of the two tail booms. These are now revealed to contain the air bleed ejectors for yaw control. I fashioned them on the model by first removing a section from the rear of each boom and adding a short length of large diameter Contrail tube cemented across each boom. The tubes were blended in with filler and the whole lot sanded to shape. Sections of smaller diameter tube were then added inside the larger tube to duplicate the appearance of the real thing.
I also removed the fins and re-cemented them at a less canted angle
—my front view drawing is inaccurate in this respect. The two underside
strakes were removed and a single one, made from circular section sprue,
added to the port side only. A cannon muzzle was added to its forward end.
The rear cross-dam in front of the main engine nozzle was reduced in width
and the two actuating arms removed — latest photos show the actuating arm
to be centrally mounted in a bullet fairing.
The aircraft has now sprouted two anti-blast strakes mounted horizontally just forward of the main undercarriage doors. These were fashioned from plastic card. Two retractable doors hinge down from their forward ends when the aircraft is in VTO mode so, again, these were added.
Finally, the aircraft at Farnborough has the avionics pod moved from
its central location above the jetpipe to the 11 o’clock position when
viewed from the rear. Its former position at 12 o’clock is now occupied
by a cylindrical brake parachute pod. Both of these changes were affected
by making new items from sprue and cementing them in their relevant places.
With all the aforementioned surgery filled and rubbed down the model was re-painted in its Farnborough colours of overall mid-grey with green camouflage blotches and Russian tail markings.
Revised and re-painted Yak-141 alongside Revell Yak-38.
Revised forward fuselage with square lower section and open canopy.
Footnote :- Since this article was written, I have had the opportunity
to visit Moscow and photograph the real thing in some detail.