LAST MONTH I took you through the assembly of the Scratch-One up to covering and finishing. This month I'll start Part Two with the covering and take you through the Scratch-One's first flights. The full-size plans were published with Part One in the November issue.

Covering and/or Painting: Whether you want to apply covering or paint is your choice. I opted to completely cover my Scratch-One with Carl Goldberg UltraCote Transparent Lite, which is an easy-to-use iron-on material. The wing must be covered since it is an open structure, so you don't have a choice in that regard.

A good source for learning about applying this material is available from Larry Sribnick of SR Batteries Inc. He has a technical newsletter series called R/C Techniques which is available for many hobby-oriented technical subjects. Volume R-13—Basic Covering Techniques—details the entire process of applying UltraCote Lite to a model aircraft.

I use two identical irons to apply the UltraCote. I learned that this material shrinks considerably at high temperatures, so I set one iron at approximately 30% power (low heat) and use it to tack the material to the wood surfaces. I set the second iron at roughly 80% power (much higher heat) and use it to make the final adhesion to the balsa surfaces and shrink out the wrinkles on the open bays of the wing. Using two irons it's unnecessary to keep changing the heat setting.

If this is your first time applying covering, be careful to remove the backing from the UltraCote. This will be a paper or a clear material, but it must be separated and peeled away from the covering. You must also realize that only one side of the UltraCote contains the adhesive, which is heat activated. If you try to apply the covering on the reverse side, it will fall off.

For your first time covering, you may want to concentrate only on doing the wing. The fuselage and tail surfaces can make do with a spray coat or two of Krylon clear or color paint.

Hinges: At this point you have a covered or painted fuselage and tail surfaces. These tail pieces have yet to be installed on the rear of the fuselage. This is a good time to add the control-surface hinges for the rudder and elevator.

The simplest technique is to use SR Batteries' Gapless Hinge Tape. It is basically clear, with a strong adhesive on one side. You cut off suitable lengths then press it into position. I usually space the elevator and rudder using a scrap piece of 1/16 balsa at the hinge line and some masking tape to hold it in place temporarily.

Keep in mind that this hinge material is not fuelproof; therefore, it cannot be used on fuel-powered models (another advantage of electric power!).

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