Definition
A very lightweight, low-density wood from the tropical balsa tree (Ochroma pyramidale), used in aircraft construction as a core material in sandwich structures and for filling lightweight components. It has a high strength-to-weight ratio for its density and is commonly bonded between layers of plywood, fiberglass, or metal skin to add stiffness without adding significant weight.
Plain English
A very light, soft wood used inside aircraft parts to add stiffness without adding much weight. It is often sandwiched between thin outer layers to make a strong but light panel.
Context Anchor
Seen in aircraft construction, repair, restoration, model aircraft building, and discussions of lightweight core materials.
Derivation
The word balsa is Spanish for 'raft,' reflecting the wood's traditional use for floats and rafts because it is so light it floats easily. That same lightness is why it ended up inside aircraft structures.
Why Pilots Care
Enables construction of light models that demonstrate fundamental principles of lift, drag, and balance during flight.
Intuition Check
Do not assume balsa is only for toys or models. Its main aviation value is being very light, and in the right design it can help make a part stiff without making it heavy.
Example Sentence 1
The mechanic found water damage in the balsa wood core of the floor panel and replaced the section before returning the aircraft to service.
Example Sentence 2
Balsa wood allows the fuselage to remain rigid yet light enough for gentle gliding flight.