3D Hobby Shop YAK55, Assembly Manual, Page: 5 / 46

Wrinkles in the Covering
Your Yak was packed at the factory without any wrinkles in the covering. You may notice some wrinkles
now; more likely, you will notice a few in a day or two or the first time you take the plane out to the flying
field. These wrinkles are the result of wood shrinkage and/or expansion. Balsa wood changes size and
shape slightly as it is exposed to varying humidity in the air. Wood also shrinks when exposed to sunlight
under dark colors of covering. This is a natural property of balsa wood. As your airplane adjusts to the
weather in your part of the world, wrinkles may appear and disappear.
Wrinkles may be removed with the gentle application of heat to the covering material on your airplane,
using an iron and/or heat gun. Apply the heat gently: the covering material will shrink as you apply the
heat, and this will remove the wrinkles. BE CAREFUL! Too much heat applied too quickly can damage
the covering, either by causing it to pull away from the wood at seams and corners or even by melting it.
Wrinkles do not affect flight performance.
Covering Materials
Your Yak is covered with genuine OraCover material. If you need to repair larger sections, matching
covering is sold at most hobby stores under the “UltraCote” brand.
Assembly Order
Like many ARF’s, the assembly order for a plane like this one is flexible. Many people choose to put the
landing gear on the fuselage first and get the plane on its wheels on a build table. Others assemble the
plane on a stand and put the gear on last. You can choose to mount the engine first, or last. The same
holds true for the radio gear. The photos in this manual are only suggestions and you may alter some
steps to suit your style. Take your time and enjoy the build, no matter what order you choose.
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