131,008. Hope, J. B. Nov. 23, 1917. Projectile fuses.-Relates to percussion fuses for bombs, which are armed by means of a wind-vane device as the bomb drops. According to the invention, the fuse comprises a firing- pin b having vanes d at the outer end, the pin being mounted so that it can rotate within a bush g, and having a safety sleeve c screwed on its inner end so as normally to protect the point. The bush is initially fixed by a shear-wire h. As the bomb drops, rotation of the firing-pin b, caused by the vanes, screws the sleeve c along the pin so as to allow the point to project. On impact, the wire h is sheared, the firing-pin, together with the parts g, c, being driven inwardly. A removable safetypin f, and a wire l for holding the vanes before use, are provided.