Definition
A method of airframe construction in which the load-bearing structure is built as a welded framework (truss) of steel tubing, then covered with a non-structural fabric skin that is doped or otherwise treated to make it taut, weatherproof, and aerodynamically smooth. The steel tubes carry all flight loads; the fabric only forms the outer surface.
Plain English
The airplane's skeleton is made of welded steel tubes, and stretched fabric is wrapped over it to create the smooth outer skin. The tubes do all the work of holding the airplane together; the fabric just covers it.
Context Anchor
Seen when learning how an airplane’s fuselage, wings, or tail surfaces may be built and inspected.
Why Pilots Care
This construction is light, relatively simple to repair, and common in many training and vintage aircraft, affecting weight, maintenance needs, and handling qualities.
Analogy
Think of a rigid frame with a tight covering stretched over it. The frame gives the strength, and the covering gives the outside shape.
Intuition Check
Do not assume “fabric” means ordinary clothing material or a weak covering. In this construction, the fabric is aircraft covering material that is stretched, treated, and finished so it can safely form the airplane’s outer surface.
Example Sentence 1
The Piper J-3 Cub is a classic steel tube and fabric airplane, with a welded steel frame covered in doped fabric.
Example Sentence 2
Before flight, the pilot inspected the steel tube and fabric covering for any tears or loose areas.