Description of explosive payloads

Characteristics of the high explosive fillers follow:

Composition A: This is the newest service explosive load. It has a damage-power factor of gain over Explosive D in the 5-inch A.A. projectile of 1.6 to 2.0, thus greatly increasing the force of the burst. A mixture of 91% RDX and 9% wax, Composition A is press-loaded into projectiles. It is a stable, non-hydroscopic explosive with an ignition temperature of 200° C. Continued exposure to temperature of 135° F or higher may cause some exudation of the wax, but this exudate is not explosive. Compared to Explo-sive D, this filler has about the same impact sensitivity, but is more sensitive to mass de-tonation and armor-piercing ignition.

Explosive D (Ammonium Picrate): Explosive D is the standard main charge for ar-mor piercing-projectiles and all other Navy projectiles over 3-inch caliber. While its power and brisance are slightly inferior to TNT, it is much more insensitive to shock and will stand impact on armor plate without being deflagrated. Its melting point is too high for it is to be melted and cast; it is loaded by being pressed into cases by a hydrolic ram. It reacts with metals to form extremely sinsitive compounds. This is counteracted by co-vering the interior of the projectiles with acid-proof lacquer.

TNT (Trinitrotoluol) is the filler in 3-inch H.C. and A.A. and 40-mm A.A. projectiles. A powerful, brisant explosive, it is easy to load by casting, since its melting point is 80.2° C. It is stable under practically all stowage conditions and should stand even bullet im-pact when cast.

Tetryl (Trinitrophenylmethylnitramine): Tetryl, because of its combination of high power, brisance, and sensitivity, has been tried for main charge loads small caliber pro-jectiles but has proved too sensitive to withstand the set-back in all but 20-mm. The melting point of Tetryl, 130° C, is too high to allow it to be melted and cast. It is loaded by being mixed with small quantities of graphite or stearic acid, which serve to lubricate it while it is being pressed into pellets. Tetryl is quite safe to handle and is extremely stable in stowage. Exposed to loose tetrly should not be handled, as it may cause der-matitis.

Pentolite: Pentolite is a mixture of TNT and PETN, usually 50/50. (PETN is similar in characteristics to RDEX. Its color is white.) It is not as stable as TNT in stowage, and separation of PETN may occur. Efforts should be made to keep it cool. It is about the same sensitivity as tetryl in drop tests, and more sensitivie than Torpex to bullet impact. This explosive filler is now used only in 20-mm loads.

Qualities of High Explosive Fillers

"A"

"D"

TNT

Tetryl

Pentolite

Velocity of detonation
at density factor

27,000 f.s.
at 1.62

21,300 f.s.
at 1.48

22,300 f.s.
at 1.55

24,400 f.s.
at 1.55

24,000 f.s.
at 1.65

Laboratory impact
value

105

99

100

45

47

Bullet impact
value

100+

100+

100

61

48

Color

White
or buff

Yellow
or orange

Straw

Light yel-
low-gray
with graph-
ite

Sand

Black Powder: Not a brisant explosive, black powder is ixed with TNT in the 5-inch, 6-inch, and 8-inch common projectiles and in the "pounder" rounds. It is also the expell-ing charge in illuminating, W.P., and "window" loads. Sensitivity to friction, black powder varies in color from brown to black.