Definition
A reference diagram used in composite material layup that shows the orientation of fibers in each ply relative to a primary axis, typically expressed in degrees (such as 0°, 45°, 90°, and -45°). It looks like a clock face with lines marking the angles fibers must follow when stacked into the layup.
Plain English
A small angle chart that tells the technician which way to point the fibers in each layer when building a composite part. It looks like a clock face, and each ply is laid down so its fibers line up with one of the marked directions.
Context Anchor
Seen in aircraft fabric covering inspection and repair, especially when checking fabric type, weave direction, or condition.
Derivation
Warp refers to the lengthwise fibers in a woven fabric — the main direction of strength. A warp clock pairs that idea with a clock face, so the angles of those primary fibers can be read off like clock positions.
Why Pilots Care
Composite parts get their strength from fibers being placed in the correct direction. If a repair ply is laid at the wrong angle, the part can be significantly weaker than the original, even if it looks identical from the outside.
Intuition Check
Do not read “warp” here as bending or twisting, and do not read “clock” as a timepiece. A warp clock is a fabric thread-count tool.
Example Sentence 1
The repair drawing included a warp clock showing the first ply at 0°, the second at 45°, and the third at 90°.
Example Sentence 2
Following the warp clock, zero degrees ran parallel to the fuselage longeron.