The new funds identified in the budget for the Op-03 sponsored Explosives Advanced Development program became available on 1 October 1977. This was the beginning of the new fiscal year. On 2 October 1977, the money was “zeroed-out” of the program. This occurred, apparently, because the new Naval officers assigned to OP-354 were not familiar with the program or with its goals. They believed that there was a more urgent need for the money in a weapon program, and redirected the funds to that effort. All of the EAD work stopped immediately. The next few months were spent writing “reclamas” and issue papers in an attempt to educate the new sponsor on the background of the program and get the funds restored.
As part of the effort justify the program and get the funding restored, I searched the NAVSEA Safety Office records (SAFEORD), the NAVSEA Explosives Branch, and the Laboratory files for data on the sensitivity of munitions to heat and bullet impact. At that time, slow cook-off, fast cook-off, and bullet impact tests were performed in accordance with WR-5036. This was the precursor document to MIL-STD-2105.37 The following table lists the data that were compiled in that search.
|REACTION||SLOW COOK-OFF||FAST COOK-OFF||BULLET IMPACT|
|LOW ORDER DETONATION||2||7||35|
|HIGH ORDER DETONATION||8||5||3|
|TOTAL TESTS PERFORMED||25||70||225|
|% VIOLENT REACTION||64||31||25|
Only reactions recorded as being more hazardous that burning was included in the computation for the percent violent reaction. The slow cook-off test consisted of the munition being placed in an oven and the temperature raised 6°F per hour until the destruction of the explosive load occurred. The fast cook-off test consisted in placing the munition either over a JP-5 fuel or a wood fire until a reaction occurred. The Bullet Impact test consisted of hitting the munition with a 20 mm AP projectile at service velocity and the results of the impact recorded.
The reactions recorded after the WR-50 tests were as perceived by the test directors. There were no standard Navy definitions for the observed reaction levels at that time. Though limited, the data demonstrated that for these three threats, slow cook-off, fast cook-off, and bullet impact, one could expect a violent reaction to occur a large percentage of the time with the munitions then issued to the Fleet.
|MUNITION||EXPLOSIVE||SLOW COOK-OFF||FAST COOK-OFF||BULLET IMPACT|
|MK-82 BOMB||H-6||NO DATA||10/37||8/33|
|ROCKEYE||75/25 OCTOL||1/1||2/2||NO DATA|
|STANDARD ARM||PBXN-101||NO DATA||2/4||2/2|
WR-50 Test results. Number of violent reactions/number of tests
Shortly before the funds for the Advanced Development program were recalled by OP-354, PBXN-101, the sensitive explosive in the SHRIKE and STANDARD ARM missile warheads was being replaced, respectively, with PBXN-106 and PBX(AF)-108. Both of these explosive belonged to the new class of tough rubbery insensitive compositions. WR-50 tests had been performed on munitions loaded with these two explosives and the results obtained supported our claims of improved safety with these materials.
Based on the above tables and on other information that soon became available, PBXN-101, Composition B, and Octol (HMX and TNT) were deleted from the list of “Explosives Approved for Navy Service Use”.38 PBXN-101, a sensitive 95% HMX and 5% polyester binder explosive composition, had been used in the SHRIKE missile warhead since 1956.
36WR-50, Naval Weapons Requirements; Warhead Safety Tests, Minimum for Air, Surface and Underwater Launched Weapons (Excluding Mine and Nuclear Weapons), Bureau of Naval Weapons, Washington DC, 13 February 1964.
37MIL-STD-2105B, Hazard Assessment Tests For Non-Nuclear Munitions, 12 January 1994.
38Ordnance Publication SW010-AG-ORD-010, List of Explosives Approved for Navy Service Use (Confidential).