Fan (machine) the airflow from the fans. Thus, fans may become ineffective at cooling the body if the surrounding air is near body temperature and contains high humidity. The punkah fan was used in India about 500 BCE. It was a handheld fan made from bamboo strips or other plant fibre, that could be rotated or fanned to move air. During British rule, the word came to be used by Anglo-Indians to mean a large swinging flat fan, fixed to the ceiling, and pulled by a servant, called the punkawallah. For purposes of air conditioning, the Han Dynasty craftsman and engineer Ding
Blown flap up room on the outside of the wing, which makes them unsuitable for use on a fighter. The principle of the jet flap, a type of internally blown flap, was proposed and patented in 1952 by the British National Gas Turbine Establishment (NGTE) and thereafter investigated by the NGTE and the Royal Aircraft Establishment. The concept was first tested at full-scale on the experimental Hunting H.126. It reduced the stall speed to only , a number most light aircraft cannot match. The jet flap used a large percentage of the engine exhaust, rather than compressor bleed air, for blowing. One