scope:

INTRODUCTION

The firing of aeroplane guns can produce significant shock and vibration loadings on the aeroplane structure and its equipment. An important load path arises from the gun blast wave propagating through the surrounding air and coupling with the adjacent aeroplane structure as a distributed pressure loading. This blast wave is created by the sudden expansion of the propellant gas from the muzzle after the projectile emerges.

This Leaflet describes the creation, characteristic and distribution of the pressure blast field arising from gunfire. The Leaflet also describes how the pressure blast field is affected by various parameters. This information is given under the following headings:

(i) Description of the Blast Field. A brief explanation of the source and characteristics of the gun blast pressure field is given.

(ii) The Effects of Aeroplane Speed and Altitude. Changes to the blast pressure field due to aeroplane velocity and altitude are described.

(iii) The Effects of Surfaces. The enhancement of the blast pressures arising from impingement of the field on surfaces is addressed.

(iv) The Effects of Gun Blast Suppressors and Deflections. The consequences of fitting gun blast suppressors and deflectors is considered.

Annex A of this Leaflet presents a method for estimating the severity of the pressure blast field arising from gunfire. The method is a simplified version of that detailed in References 1 and 2.