A far more ambitious follow up aircraft type would be the YAK-141, that got NATO codename "Freestyle". This aircraft design started as early as 1975 as a single seat high speed fleet defense fighter. This required a straight but also a swivelling jet exhaust for the R79 engine, that was situated between two tail fairings. Two RD41 engines were installed to provide vertical thrust at the forward airframe section aft of the cockpit with ventral doors. 

First flight was in March 1987 and the first complete transition from vertical to high-speed flight and vertical landing June 1990. Testing on the carrier Admiral Gorshkov started in September 1991. A big accicent occurred during a carrier landing but the pilot ejected safely. 

After the fall of the Berlin wall and Iron Curtain, the political situation changed. Soviet Defense budgets were dramatically cut. The Yak-141 program progressed at a very slow pace, with two flying prototypes and ground test article. It did not really mature into an operational aircraft and in reality the program ended in 1992. 

ART model issued a YAK-141 kit  in 1/72 scale in 2012.  It costs about EUR 20,- (Spring 2012). 

There are 7 sprues in light grey plastic and a transparant sprue with the canopy and windscreen. Two resin parts are also in the kit for the K-36D seat and the jet exhaust pipe. Although the kit looks to be short run, the parts are very fine. Panellines are engraved. Parts for 2 types of missiles, the R73 and R27 are also in the kit. 

Option is to set the main jet exhaust in the cruise position or a vertical position with open ventral doors. 
A nice decal sheet comes with the kit for 4 schemes of grey aircraft, the buzz no "77" and "141" schemes are only shown on the instructions. 

The instructions are drawn in Computer graphics but are a bit unclear. Parts to be assembled are shown on the graphics but no clear arrows where they should go. Also, colour information is vague, numbers are indicated but I don't understand what they mean. 
 

OK, let's start modelling this kit.

Assembly does not follow the usual order in aircraft kit. To begin with, I opened up the engine air intakes area in part 20 bulkhead. The assembly of the side fuselage parts and lower and upper parts requires careful alignment and filling and sanding with putty. Take care here, it will save a lot of work later on.

In the tailboom fairings and tail (parts 11, 12) , I had to fill the shrinkage with putty.

The nose is separate from the rear fuselage. The kit cockpit is basic but small. The K-36 seat is nice being a resin part but this was installed later on. The cockpit interior I painted medium grey.

Filling and sanding was needed at various places but nothing hard and that can not be taken care off. I used ALABASTINE CAR FILLER, which is a white colour putty. This is a fine putty that is cheap, does not shrink a lot and is very fine.

The flying surfaces edges like the rudder and ailerons were sawed in for greather realism with a TIGER razorsaw. 

The vertical engines show a gap here, but the door will be set closed so no worries here.

After sanding, the overall model got a coat of base grey applied with the airbrush to check for any flaws. Some small work was still needed.

The overall scheme picked was for the "77". For the overall grey, Revell Aqua acrylic No.57 grey was used. Also the pylons were added at this stage to spray these as well with the Harder Steinbeck airbrush. The radar nose got a darker grey paint.

The vertical engines show a gap here, but the door will be set closed so no worries here.

Next the kit decals were added. They are fine. 

The one piece canopy was cut with the TIGER razorsaw to separate the windscreen. Note that the canopy hood swivels open to the right. The canopy framing was hand painted.  The seat got a lighter grey coat with painted details like a black headrest. 

Some details were added with straps made from blue decals.

The markings came straight from the kit with the decals. After decal application, these were protected by adding a couple op coats of of Johnson Future

The kit has parts for missiles, but I had an already painted spare missile from another kit, this was added. Some new small pitiot tubes were added from scratch below the nose. 

The result...
..

This model is very nice and the ART MODEL kit can be recommended. 
 

References:
http://en.wikipedia.org/wiki/Yakovlev_Yak-141

YouTube film:  http://www.youtube.com/watch?v=fGPLQN18Ej8