There are numerous ways to make current, to the ball of yarn did not run away and not out somewhere. The easiest is to put it in a box, basket, or, as shown in the drawing, just the right size jar.
Recommend to read
IN THE AIR “SCHEMATICA”
Elegant appearance, ease of fabrication, lack in construction materials in short supply, good flight characteristics are qualities that distinguish a schematic model of the airframe...
UNDER THE NATO STANDARD
In early 70-ies of XX century views on the use of surface naval forces has changed significantly. In the West, only one country — the United States continued to rely on shock aircraft...
