Grape Jelly

Grape Jelly (グレープゼリー) is the name used to refer to special fuel-air bombs used by England. They are first introduced in the 8th Shinyaku Toaru Majutsu no Index light novel, and was shown being used on the Sargasso of the North Sea near Iceland during the Anti-GREMLIN Alliance attack there along with the Mont Blancs.

Principles
The missiles are fuel-air bombs that are detonated 10,000 meters above their target area, as was the case during the attack on Sargasso. A special combustible substance packed in a metal case was chemically made to expand, turned into an aerosol, scattered over an effective range of several hundred meters, and ignited. This allowed the weapon to cover a broad area in flames and explosive pressure. It was classified as a normal weapon that did not use nuclear technology, but it was rumored to have the destructive power to produce a mushroom cloud if used on a large enough scale. In this case, a parent metal case produced several dozen child cases, each child case produced several dozen grandchild cases, and those finally scattered and detonated great amounts of the combustible material at just several dozen meters above the surface.