Kaye flapped his arms and clucked, giving the waiter an imitation of a chicken. At noon it flapped its wings and spread out its feathers. The wings were flapped by gunpowder charges activating a Bourdon tube. The wings during flight are flapped rapidly, and are frequently used during foraging. The candles flapped in the first warning gust of the monsoon. This allophone has been called "flapped" and "slapped". The wing is not flapped very far below the horizontal. It is particularly suitable for cross-country instruction and training to fly flapped gliders. Manufacturers started to exploit this potential by offering tip extensions for their flapped sailplanes. Flapped fricatives are theoretically possible but are not attested. The Rave broke new ground in the development of flapped foils and control systems. "Flapped" fricatives are theoretically possible but are not attested. Flapped fricatives are possible but do not seem to be used.