Broad Temperature Range Obturator Pad Materials.
WATERVLIET ARSENAL N Y
Pagination or Media Count:
It is important that obturator pads seal satisfactorily over a wide range of ambient temperatures. This is difficult to achieve at very low temperatures, where the elastomeric pad materials become stiff and fail to transmit pressure hydrostatically as they must for effective obturation. Furthermore, since the coefficient of thermal expansion of an elastomer is about 10 times that of steel, the pad shrinks much more than does its cavity in the breech assembly as the temperature falls. Methods were developed for evaluating these characteristics of candidate materials simply and inexpensively. The most promising elastomer was the castable polyurethane made from Adiprene L-42. Adiprene-fiber glass pads have sealed well in both the 175mm Gun M113A1 and the 155mm Howitzer M185 from 125 down to a temperature of -50F in climatic firing tests at Aberdeen Proving Grounds which corroborates these ideas on the design of obturator pads and the shop methods of evaluation.
- Laminates and Composite Materials