Fu-Go was an incendiary balloon weapon deployed by Japan against the United States during World War II. It consisted of a hydrogen-filled paper balloon 33 feet (10 m) in diameter, with a payload of four 11-pound (5.0 kg) incendiary devices and one 33-pound (15 kg) high-explosive anti-personnel bomb. The uncontrolled balloons were carried over the Pacific Ocean from Japan to North America by fast, high-altitude air currents, today known as the jet stream, and used a sophisticated sandbag ballast system to maintain their altitude. The bombs were intended to ignite large-scale forest fires and spread panic.
Fu-Go balloon bomb
Fu-Go carriage, with labeled ring, electrical circuits, fuses, ballast, and bombs
Top view of carriage assembly, with control device removed
Altitude control device, with central master aneroid barometer and backups
An incendiary balloon is a balloon inflated with a lighter-than-air gas such as hot air, hydrogen, or helium, that has a bomb, incendiary device, or Molotov cocktail attached. The balloon is carried by the prevailing winds to the target area, where it falls or releases its payload.
Balloon launch for Operation Outward. Felixstowe, Suffolk, England
Re-inflated Japanese Fu-Go balloon bomb