Dymaxion Deployment Unit
Fuller's 1940 round, corrugated-steel emergency shelter—an adaptation of the grain-bin form mass-produced for wartime military use.
The Dymaxion Deployment Unit (DDU), sometimes also called a Dymaxion House, is a structure Buckminster Fuller designed in 1940: a 20-foot circular hut of corrugated galvanized steel resembling a yurt or the top of a metal grain silo. The interior was insulated and finished with wallboard, portholes, and a door, while the dome-like ceiling carried a ventilation hole with a cap—an application of the convection "dome effect" Fuller had studied in his grain-bin housing experiments.
The Chilling Dome Discovery (August 1940)
During a sweltering Kansas heat wave, a visiting business partner discovered the DDU interior remained surprisingly cool despite intense external temperatures. Fuller initially attributed the effect to Bernoulli's principle, but physicist Chris Weekes later identified more accurate explanations: "acceleration under conservation of energy; as well as adiabatic expansion" following first law thermodynamics.
The mechanism operates as a "reverse chimney effect": heat from sun-baked exterior walls drives convection updrafts on the dome's outer surface, drawing air from below through short wide openings at the base. Air is simultaneously drawn inward through the narrow top vent, where it accelerates — converting thermal energy into kinetic energy. Upon entering the lower-pressure interior, further adiabatic expansion produces additional cooling, analogous to air released from a compressor valve developing frost.
Design parameters: small inlet vents at top, larger outlet vents at base; darker dome coloring enhances performance (stronger solar absorption → stronger convection); stack tapering may increase velocity as cooling air contracts. Limitations: requires direct sunshine on exterior walls; non-functional at night or in shade; lateral breezes interfere with the vertical airflow pattern. Fuller incorporated this passive cooling into geodesic dome designs throughout his career, installing multiple lower-edge vents with greater total area than upper inlets, and envisioned computer-controlled electronic vents for seasonal management.
The DDU adapted an inexpensive, factory-made product for rapid emergency shelter. The Army Signal Corps commissioned Fuller in 1942 to produce 200 units as quickly as possible; they were manufactured by the Butler Manufacturing Company and shipped to military bases around the world in the early 1940s. Each unit cost about $1,250. The wartime shortage of steel, needed for armaments, led to cancellation of further production.
A cluster of DDUs survives at Camp Evans in Wall, New Jersey—now the InfoAge Science/History Learning Center—where roughly a dozen units remain and historic aerial photos show two dozen or more once stood between the base's large H-shaped buildings. Many concrete pads survive where units were later removed, having served for hazardous-materials storage and small shops.
See Also
- R. Buckminster Fuller — the central figure
- Dymaxion House — the related prefab dwelling and shared name
- Fuller and the Military — the broader military relationship that produced the DDU commission
- Passive Cooling Geometry (Passive Cooling Geometry) — the physics of dome cooling geometry
- Geodesic Dome (Geodesic Dome) — where Fuller applied DDU cooling lessons
- Geodesic Dome Passive Cooling (Geodesic Dome Passive Cooling) — the 1940 cooling discovery made in the DDU
Sources
- Dymaxion deployment unit (Wikipedia)
- Fuller's Chilling Domes Physics