Downloaded from https://www.everyspec.com MIL-STD-81OC Wp = weight of projectile (lbs) muzzle velocity of projectile (ft/see) g= 32.17 ft/sec2 Table 519.2-IA is a general table which relates typical gunfire configurationsto aircraft types.. To facilitate identificationof the ballistic parameters that axe necessary to determine the gunfire vibration levels of 3.3, table 519.2-IB is provided. The table includes values of E, r, n and the muzzle velocity v; the table also ‘includesthe reference gun parameters of the M61. Table 519.2-IC is a repeat of this table using metric equivalents. Finally, a brief array of English-to-metricconver- sion constants are provided’as specified in table 519.2-ID.
3.3.2 Adjustments of Gos, Gor (primary structure). The two O dB parameters shall be adjusted to account for the following additional conditions: gun standoff distance (H), gun muzzle configuration (M), equipment depth.para- meter (R) and equipment mass loading (W). The adjusted‘valuesG:s and G~r are the final O dB values from which the magnitude of any point (Gs, Gr) is established on the prediction surfaces of figures 519.2-2 through 4. These values and the individual adjustments are expressed in decibel form as follows:
10 loglo G~s = 10 loglo Gos +A h+% rs rs +A+ARW (4) 10 loglo G~r = 10 loglo Gor ‘+Ah + rr,” rr +A+ARW (s] 10 loglo G~s= final, adjusted O dB value of the sine r 1 s surface; referenced 10 loglo G~r = final, adjusted O dB value, of the random i-r surface; referenced to rr Ah = reduction due to gun standoff distance (dB) ~ = reduction due to gun muzzle configuration (dB) AR= reduction due to depth parameter (dB) Aw = reduction due to mass loading (dB) k113TtOD” 519.2 519.2-4 /