Its not every day that you get the chance to fly a direct descendant of a Russian World War II fighter plane. And, after 9,000 hours or so of rebuilding what started out as a pile of scrap, Mark Jefferies of Yak UK is justifiably protective of his pristine beauty, so I felt very honoured when he gave me the opportunity to have a fly of his C11. Even better was the news that we would be joined by a second C11 which would be turning up for the photo shoot.
The C11 cuts an impressive figure parked alongside the Cherokees and Cessna's on a typical flight line. The aeroplane has a beefy and brutish fuselage with uncharacteristically thin wings and tail surfaces, its WWII heritage is unmistakable. The construction is a mixture of steel tubing and metal skinning for the forward fuselage, with fabric covering aft of the mainplane. The wings and tail surfaces are skinned in metal and the ailerons, rudder and elevator panels revert to fabric. The Yak sits on a wide-tracked, inwardly-retracting undercarriage and a small, non-retracting tailwheel. The brakes have been modified from the standard pneumatic drums to a set of hydraulic Cleveland discs which originated in a Cessna 421 – the aircraft is based on an 800 metre strip and discretion is always the better part of valour.
The Yak 11’s 700 horse power, seven cylinder ASH 21 radial is hidden behind a tight fitting cowling with a cooling gill arrangement which will be familiar to anyone who has seen a Yak 52 from the front. Access to the cockpit is easy – simply climb up the trailing edge of the wing and push in the knob at the front bottom corner of the forward or aft canopy. The cockpit interior is relatively large for a military machine and, not surprisingly, devoid of luxury, although the seats themselves are comfortable. Cyrillic script makes everything alien to a westerner, although CAA-approved labels take care of the important bits. Needless to say that
a thorough check out is a necessity before you could even contemplate starting the engine, let alone taking this thing into the air.
Strapping in is one of the easiest bits of the conversion course but be careful
with the canopy – if you have flown a Yak 52 it would be easy to reach for the toggle above your head to close it. Unfortunately all that will do is release the canopy’s securing pins and allow the whole caboodle to fall of the back of the fuselage. Not good. Instead use the little knob at the forward corner and make sure that it is fully home before you try to take off. The canopies are allowed to be opened in flight, though.
The engine is turned over pneumatically. An ingenious priming device means that you don’t have to get someone to pull the prop through while you hit the plunger, as on typical radials (although the pull-through to clear the bottom cylinders of oil still has to be done if the aeroplane has been left standing for a few hours). Instead an internal priming cylinder is charged with fuel using a lever on the lower right of the cockpit before hitting the firing button on the left of the instrument panel. The venturi effect of blowing air over the top of the priming cylinder sucks just the right amount of fuel to be carried into each cylinder in turn. This mixture is ignited by a shower of sparks and the engine bursts into life, accompanied by a satisfying puff of smoke from the exhaust stubs. Not as easy as a light aircraft engine, but straightforward once you have done it a few times.
Anyway, successfully lighting a radial is a pretty cool thing to do….
Taxying the Yak C11 is a doodle after all that starting palaver. The aeroplane feels heavy on the ground but the toe brakes fitted to Mark’s aeroplane make steering easier. Power checks and pre take-off drills are pretty standard but, as in the newer Yaks, you do have to make sure that cowl flaps are open. There are two types of Yak pilots – the ones who have taken off with the cowl flaps closed, and the ones who haven’t yet but will do so in the future.
Lining up at Little Gransden the aircraft was allowed to run forwards a few feet to make sure that the automatic tailwheel lock had engaged with aft stick before full power was applied. The aeroplane didn’t swing particularly and the lack of action outside allowed a prolonged check of Ts and Ps before it was time to rotate. This Yak seemed reluctant to break free of the ground, instead wobbling alternately on the main wheels before lift off was finally achieved with a firm pull on the stick at 90 knots. Once airborne the gear was raised and the power brought back to 75% with the throttle and rpm lever for a leisurely climb at 135 knots. The
VSI will show 1,600fpm at max weight and max power. The cylinder head is less willing to climb towards the red line than with Vedeneyev-powered aeroplanes like the Yaks and Sukhoi.s familiar to western pilots. I was immediately impressed by the 11’s control lightness and harmony, spot on at low speeds, although the ailerons harden up considerably at higher velocity. Surprisingly, the roll rate was less than a Yak 52, perhaps 90 degrees per second at cruising speed compared to 120 degrees per second for the ’52. With hands off the aircraft exhibits positive stability in all directions – a good weapons platform.
The canopy affords a good lookout and the aeroplane feels natural in the air, not the viceful monster that you might imagine a WWII-derived Russian fighter might be. I was certainly aware of the high wing loading, though. The Yak 11 was going places quickly once the nose was lowered, and the wings cut through turbulence like a knife through butter as I turned towards Duxford for our rendezvous.
With the throttle left wide open the C11 records an impressive speed, 225kt TAS at 1,000 feet, for an equally impressive fuel burn, for the wrong reasons, of 50 gallons per hour. At 75% power the speed and fuel burn drops to a respectable 200 knots and 33gph, and the aeroplane becomes frugal at 140 knots, using just 16gph. It is no surprise that with the headset off the noise is pretty stupendous as sound insulation is nowhere to be seen on the inside of this aeroplane. Outside is a different matter, though – the Yak C11 is surprisingly quiet from the ground.
Aerobatics in the Yak 11 are a joy. Once you get the thing heading downhill the speed builds quickly, and loops 2,000 feet in diameter are easy to accomplish. The speed washes off quickly in the vertical and energy management is much more important than in higher powered warbirds such as the Spitfire. Having 700 horse power bolted onto an aeroplane which was designed for over 1,200 has an obvious result. Nevertheless, for the average PPL the Yak 11’s performance would seem impressive in any case.
The stall is interesting, to say the least. The aeroplane exhibited a pronounced starboard wing drop in all configurations and power settings, the severity of the wing drop dependent on the power applied. I would not be surprised if the flow over the wing is pretty much laminar – it is either flying or it isn’t and there isn’t much in the way of warning buffet when the G break is about to happen. Equally interesting is the aeroplane’s ability to flick into a steep, mind-numbing spin. Spin recovery is predictable, though, and the aeroplane always comes out cleanly within 90 degrees of rotation.
In the circuit the Yak C11 is typically difficult to slow down and it takes a while to get the airspeed low enough to meet the gear and flap limits of 163 and 135 knots respectively, even when the throttle is fully closed.
The best approach to make is a curved one as the visibility over the nose is poor – non-existent from the rear seat. I can imagine that Russian instructors had to be made of stern stuff when allowing their students to fly from the front seat. There’s not much for the rear seater to do on short finals other than close his eyes and say a prayer. The landing flare needs to be positive but, once on the ground, the aeroplane stays put. Directional control is adequate all the way down to a walking pace. The brakes are very powerful and the stick needs to be brought back to prevent a noseover before any large pressure is applied. The original
pneumatic brakes are more forgiving than Cleveland discs but less effective.
Eddie Coventry’s Yak C11 (our platform for the photo shoot) is for sale at the moment for £170,000, comparing favourably with Harvard prices – and that’s only half the aeroplane that the Yak 11 is. You get the buzz normally associated with aeroplanes such as Spitfires and Mustangs for between half and a third the purchase price and a quarter of the operating cost. A figure of around £250 per hour excluding hangerage would seem reasonable for a well utilised aeroplane. Spares are not too much of a problem – there are several small inventories in the UK and more overseas, especially in Russia and the USA.
For about half the purchase price and the same hourly charge as a Yak 11 you could run a JP3 on a UK permit and go a little faster in the process. You may not get to the opportunity to put your JP3 on the display circuit as there are plenty out there already, but if displays aren’t your bag you would probably be better off in the jet.
What about converting a Yak 11 back to its more agile ancestor the Yak 3? Don’t try it, someone just did. The job took over five years at the Yak factory and the cost was rumoured to be more than the original purchase price of the aeroplane. Could a PPL fly a Yak 11? No problem, but expect to spend as much as 10 hours converting onto the type depending on total flying hours and tailwheel experience.
As the end of the Second World War approached the Russian government announced plans for a new two-seater to replace its obsolete fighter trainers, the Yak 7 and U12. Part of the requirement for the new aeroplane was that it should have the same handling qualities as the fighter aircraft then in use. Yakolev’s initially simple answer to this was to convert one of its most successful fighter aircraft, the small but agile Yak 3, into a two-seater. The Yak 3’s big V engine was replaced with a lower powered radial and the forward fuselage was altered quite a bit to accept this change, but otherwise the original design was hardly altered. The new aeroplane flew for the first time in November 1945 and was a success although the government delayed signing an order straight away. Yakolev’s response was to fiffle and refine the basic aeroplane until a deal was finally struck a year later. By this time the aircraft featured an increased wingspan over the Yak 3, , non-retractable tailwheel and an increase in max take off weight. The max level speed had dropped to 250mph, down quite a way from the 300mph prototype, and the name had changed to Yak 11.
In addition to the 3,800 aeroplanes eventually built by Yakovlev (big numbers you’ll agree) a further 700 were built as C11s under license in Czechoslovakia. The aeroplanes made their way into the majority of the Warsaw Pack countries in the role of advanced fighter trainer until the early 1960s. The Yak 11’s ability to carry a 12.7mm machine gun in the nose plus two 220lb bombs made it desirable as a light attach aircraft and many third world countries used it as such. Egypt was one of these and this is where both Mark Jefferies’ and Eddie Coventry’s aeroplanes originate. Both aircraft were bought from French aeroplane trader Jean Salis before being extensively restored. The saga of Mark’s own rebuild would make a feature length story in itself, the aeroplane finally being unveiled to the public at the 1994 PFA Rally at Cranfield where it won the prize for Concours de Elegance. And deservedly so.
When Mark Jefferies purchased his Yak C11 from Jean SallisSalis in 1991 the aeroplane was something not much better than a pile of scrap metal – a £60,000 pile of scrap metal to be exact. The original aircraft had started life at the Let factory in Czechoslovakia in 1956 and saw service with the Czech Air Force before moving onto serve with the Egyptians (another Yak C11 force landed in Cyprus on its way to Egypt and impounded by the British, eventually ending up on the English register as G-AYAK). For the Jefferies Yak, years of dereliction followed before Jean Salis secured its purchase along with 41 other aeroplanes of varying degradation. Mark spent three years and 9,000 hours of labour restoring his aeroplane, accumulating a telephone bill along the way that would even make British Telecom blush. Many parts had to be made from scratch using the rusted originals as patterns and some Yak 50/52 components also made their way into the project. Vintage Engine Technology, also based at Little Gransden with Yak UK, took care of the engine rebuild. Considering the engine’s age surprisingly little remedial work was necessary once a new set of cylinders had been sourced. The aeroplane is now immaculate in every respect and its Concours de Elegance prize at the ’94 PFA Rally was no surprise to the people who have seen it at close hand. Mark Jefferies is now rebuilding a C11 for a German customer with an even higher specification.
70% 195kt Max t/o weight 2,150kg
Stall 83kt t/o run 575 metres
Wing span 9.53 metres Engine Ash 21, 700hp