Troublesome activity, building profiles of the wing flying model aircraft. We have to count tens and hundreds of the coordinates of the ribs in accordance with the selected size of the chord. Using the usual linear, it is difficult to determine with sufficient accuracy the true value of a cross-section of the eye does not “catch” and a few tenths of a millimeter… And it is from these shares often depends on the manufacturing quality of the wing model and eventually its basic flight characteristics.

Using the proposed method, it is possible to build accurate cross-section of the ribs in the desired scale without special tools.

This is done so. On the sheet you need to draw a horizontal line on it to postpone a length of 100 mm. At the end restore the perpendicular height equal to one-tenth of the theoretical length of the rib. Through the beginning of the segment and the size of the normal conducting line. Received a right triangle is the basis for all further work.

From the beginning of the horizontal segments sequentially delay to 10 mm, corresponding to 1% of the chord of the profile of the future. Through the plotted points carry out a vertical line — the preparatory work ends.

Now let’s suppose you want to determine the size of the desired cross-section, corresponding to 5.5% of the chord length. From the left end of the horizontal delay of 55 mm. From the resulting point restore perpendicular to the intersection with the hypotenuse of the triangle, its length will be 5.5% of the chord. This size is transferred to the profile design. If any coordinate would be over 10%, extending the triangle to the right. For repeated use of such a large pattern it can be made not from paper but from thin scraps of aluminium, this will increase the accuracy of the sizing.

**I. Grigor’EV, Kazan, Russia**

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