"the light, piping whistle of the low spreading daisy cutters"
Daisy Cutter
Public DomainDaisy Cutter - Credit: U.S. Air Force

"Daisy cutter" bombs had fuses designed to detonate just before they hit the ground, in order to increase blast radius and shrapnel velocity. They were first used in 1918, when the Germans attacked an airfield of the Royal Air Force at Bertangles.  

Such fuses are still in use today.