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Yak52 plans are available from: Airborne Plans Service for AU$33.00 plus P&H2 (AU$3.00 within Australia). Plan No. 659
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Yak 52The Yak 52 is a two seat aerobatic aircraft derived from the single seat, tailwheel Yak 50.. The Yak 50 was developed in the USSR during the mid 1970's and was a winner at the World Aerobatic Championships in Kiev in 1976. Its strong, robust airframe powered by a huge radial engine made it possible to perform all manoeuvres with smooth precision.

Airborne's sport-scale aerobatic model captures the wonderment of this classic styled Russian aircraft with a simplified structure that ideally matches a good .46 - .52 engine.

The tricycle undercarriage makes for good ground handling. In the air the model is fast with crisp controls and will perform anything in the book. The Yak 52 is frequently seen at airshows throughout Australia sporting some very flashy colour schemes offering the avid modeller a good opportunity for scale detailing.

FLYING THE MODEL
To me, this is a nice flying model. The Yak takes off in around 15 metres.

At sea level it should do better than that, our model field is fairly high, with an altitude of 3300'.

Yak52 componentsAfter getting a bit of pace up the Yak climbs well. Manoeuvring needs to be smooth as the Yak tends to flick with abrupt movements with the airspeed too slow. My first flight with this aircraft was very short. Being used to flying slower aircraft, I tried to take-off too slow and with too much elevator movement and the aircraft flicked into a cartwheel. The damage was minor, a broken prop, engine mount, dented cowl (and pride) and a bit of bruising. After 3 hours repairing the next take-off was on low rates and successful.

I have only been flying models for around 1 year, having flown a low wing model the Yak wasn't that hard. The main trouble I had with this aircraft, was keeping up with it as it is fairly fast. After a couple of flights it seemed a lot more manageable. The Yak goes where you put it and stays there (1 think you call it neutrally stable).

When the aircraft has some speed up it doesn't move around much in the air. Some models bounce around, the Yak seems like it's on rails. Fast low passes are easy and look great. Rolls are subdued with the movements I have. The roll rate is around 90 degrees per second. Loops are big, if the airspeed is kept up the aircraft can manoeuvre tightly. Snaps or Flick rolls are quick, the aircraft spins well and stops instantly with the sticks neutral. A low big barrel roll looks impressive. Stall turns are easy with the big rudder and plenty of movement.

Something that looks good is dive to gain lots of pace, then pull up nearly to the vertical and pole over slightly so there is slight negative G, then do a negative flick (full forward with full right aileron and full right rudder). The Yak will do two or three somersaults, a book I have calls that a Lomcevak. ( a rolling tumbling thingy).

Yak52 WingLanding is easy, with a bit of breeze the Yak slows up well. On approach some power is needed as the cowl is very draggy. If the engine fails the nose has to be lowered quickly to keep the speed up. There is not much gliding range unless you have plenty of height. Ground handling is very good. Most of my flying has been on taildraggers, the tricycle makes ground work easy and taking off and landing straight forward. Generally an easy and predictable aircraft to fly.

BRIEFLY BUILDING
At the time I received the plans I was busy making a living, so my father Peter did all the hard work. I had the easy bit of covering and finishing.

FUSE
Build the fuse on the plan the same way your Hustler or Telemaster is built.

Yak52 Engine CowlFor the turtledeck, sheet as the plan or plank. The tailplane is straight forward and can also be built over the plan. For the cowl Airborne has a very detailed article in issue 147 September 1996 ( back issues available I hope). The only change we used from the plan with the cowl was 1.5mm ply for the rear panel instead of 3mm balsa. The balsa would have been lighter but for a pilot of my skills (or lack of) ply is more durable.

I have fitted a Rob Russon Pitts style muffler. The muffler is very well built, the engine has more power with only a small mcrease in noise and fits very neatly inside the cowl.

WING
The ribs are hard work as every rib is a different size. I read in an old magazine about photocopying the ribs off the plan then ironing the paper onto the balsa.(dry iron) This makes a good copy onto the balsa and saves the time and hassle of tracing. Assemble the ribs and spars over the plan upside down, using the building tabs to keep the wings square. Cyno makes a quick, light structure if you can put up with the smell. We used Aquadhere which slows the building a bit. After fitting the leading and trailing edge the wing doesn't have much rigidity. The leading edge sheeting helps this. For the sheeting lift the wing from the plan and do the topside first as this is flat and then it can be laid back on the plan for the bottom sheeting, this keeps the wing flat and rigid until the D-section is completed. The wing should now be straight and strong ready for trailing edge sheeting, capstrips and tips. The servo mount is simply a hole cut in the top sheeting with a ply square on top. The aileron torque rods are mounted in the trailing edge of the centre section.

CANOPY
Yak52 PaintedMy canopy is made with flat sheet, the windscreen is made of slightly thicker sheet. The little eyebrow window above the windscreen was made with a piece of moulded cover wrap from the kids toys. I then cut black contact into thin strips and covered the frames. The contact was a bit loose but shrunk well. (use a lower heat for the contact or it will melt instead of shrinking). I also used contact on the anti-glare panel on the cowl and in front of the windscreen (this was not shrunk).

FINISHING
Pushrods are used for elevator and rudder with snakes used for nosewheel steering and throttle.

I have covered the Yak in Profilm and found it very strong, easy to use and looks very good. You can use it for trim, the stars were easy to put on with no bubbles. With the enclosed engine I used a Dubro fuel valve. The tank is 300ml and lasts for 10 minutes at flat stick.

SUMMARY
Yak52 FlyingAfter the first couple of flights the engine showed signs of overheating. There was plenty of intake but not enough air coming out. To cure this I cut 5 sets of 1ouvers around the cowl like a Sukhoi 26 or a Yak 55, also an undercut at the bottom of the cowl. This has cured the problem.

There are a number of choices for building without changing the plan too much. The Yak 50 would make a good looking, lighter machine, or the Yak 53 a single place tricycle. I now have heaps of hours flying on the Yak, the more I fly it the easier it seems. I found my Yak fast and easy to fly, a very appealing aircraft that is a bit different.


SPECIFICATIONS Yak52

Type: R/C Scale Model
Wingspan:
1.45metre
Weight: 3.0 Kg
Engine:
.46 - .52 2 stroke
Radio:
4 function R/C required



Yak52 plans are available from:
Airborne Plans Service
AU$33.00 plus AU$3.00 P&H1

Plan No. 659

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This page was last modified on the 21-May-02