Duramold
A heat-and-pressure molded wood composite developed for lightweight aircraft structures.
Duramold is a lightweight composite material created by Virginius E. Clark. The process involves soaking thin layers of birch or poplar wood in phenolic resin, then pressing and heating them together in a mold at 280 °F (138 °C). The result is a strong structural material similar to plywood. During World War II, when aluminum and steel were hard to come by, Duramold and a comparable material called Haskelite became vital substitutes.
Compared to metal, Duramold offers advantages in strength, weight, and ease of construction. For example, a Duramold cylinder under compression is 80% stronger than a duralumin cylinder of the same weight per unit length. More than 17 versions of Duramold were made, using different wood types in thin plies. Besides aircraft structures, the process was also used for radomes and missile bodies.
Clark developed Duramold for Fairchild Aircraft, working with George Meyercord of the Haskelite Corporation. Fairchild patented the process, built the first Duramold aircraft—the F-46—and formed the Duramold Corporation. Several aircraft used Duramold in parts, but the largest was the Hughes H-4 Hercules, designed by Howard Hughes and Glenn Odekirk, which was built almost entirely from Duramold, including very large sections. Hughes Aircraft bought the rights to use Duramold on aircraft over 20,000 lb, while Fairchild and Meyercord kept the rest. However, the material proved poorly suited for heavy aircraft.
The Duramold and Haskelite process first appeared in 1937. Later came Gene Vidal’s Weldwood and the Timm Aircraft Company’s Aeromold process, which bakes at a lower 100 °F (38 °C) for cutting and forming, then 180 °F (82 °C) for fusing sections after adding resins. In the United Kingdom, the De Havilland Aircraft Company used similar composite construction for aircraft such as the DH.88 Comet, DH.91 Albatross, Mosquito, and Vampire.
- Developer
- Virginius E. Clark
- Development partners
- Fairchild Aircraft, George Meyercord of the Haskelite Corporation
- First developed
- 1937
- Curing temperature
- 280 °F (138 °C)
- Strength claim
- A cylinder in compression made of Duramold is 80% stronger than a cylinder in compression of the same mass per unit length made of duralumin
- Varieties
- Over 17 varieties of Duramold were developed
- Largest aircraft using it
- Hughes H-4 Hercules
Lore & Background
Virginius Clark developed Duramold for Fairchild Aircraft, working with George Meyercord of the Haskelite Corporation. Fairchild patented the process, designing and constructing the F-46 as the first aircraft made using the Duramold process, and forming the Duramold Corporation. Several aircraft used Duramold in parts of their structure, the largest manufactured with the process being the Hughes H-4 Hercules designed by Howard Hughes and Glenn Odekirk, which was built almost completely with Duramold including very large sections. For this use, Hughes Aircraft bought the rights to the use of Duramold on aircraft exceeding 20,000 lb; Fairchild and Meyercord otherwise retained the rights, but the material was found to be poorly adapted to heavy aircraft.
The Duramold and Haskelite process was first developed in 1937, followed by Gene Vidal's Weldwood and later the Timm Aircraft Company's Aeromold process, which differs in that it is baked at a low 100 °F (38°C) at cutting and forming, and 180 °F (82°C) for fusing together sections after the resins are added. In the United Kingdom, the De Havilland Aircraft Company used similar composite construction for aircraft, including the DH.88 Comet, DH.91 Albatross, the Mosquito, and Vampire.
The material has some advantages over metal in strength, construction technique, and weight. A cylinder in compression made of Duramold is 80% stronger than a cylinder in compression of the same mass per unit length made of duralumin. Over 17 varieties of Duramold were developed, using various combinations of types of wood in thin plies. The Duramold process has also been used to make radomes for aircraft, as well as missile bodies.
Reader's Guide
Duramold's significance lies in its role as a critical substitute for aluminum alloys and steel during World War II material shortages. Developed by Virginius E. Clark for Fairchild Aircraft, the process allowed the construction of lightweight structural components from birch or poplar plies impregnated with phenolic resin and cured under heat and pressure. Its notable strength advantage—an 80% greater compressive strength per unit mass compared to duralumin—made it attractive for aircraft construction. The Hughes H-4 Hercules, built almost completely with Duramold, represents the largest application of the process, though the material was found poorly adapted to heavy aircraft. Over 17 varieties were developed, and the process was also used for radomes and missile bodies. The Duramold process was patented by Fairchild, which formed the Duramold Corporation and built the first Duramold aircraft, the F-46. Hughes Aircraft purchased rights for aircraft over 20,000 lb, while Fairchild and Meyercord retained other rights. The legacy includes influencing similar processes such as Gene Vidal's Weldwood and Timm's Aeromold, as well as De Havilland's composite construction in the United Kingdom.
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