Modern guided weapons have revolutionized air-to-ground warfare and there are remarkable improvements on the way. By the turn of the century, a single aircraft will have the capability to “drop bombs on multiple targets with little regard to release altitude or delivery maneuver. Planes and missiles will be able to deliver the new weapons on one pass in bad weather with great precision”.93 These will be costly weapons. Thus, the effort to make them as insensitive as possible is worth the effort both from the logistics and the operational viewpoint. Spending money now to make them meet the IM requirements will pay dividends later.
There is a strong commitment in the Navy to provide safe and insensitive munitions to the Naval forces without sacrificing combat readiness or effectiveness on target. This does not mean that all of the technical requirements for Insensitive Munitions must be met before a munition is accepted for service use. If there is an operational need, waivers will be granted pending the development of technology to solve the problem.
Incremental improvements in the sensitivity characteristics of munitions are desirable and achievable. For example, when loaded with PBXN-109, the MK-82 and MK-83 General Purpose bombs and PENGUIN missile warheads meet all of the IM requirements except sympathetic detonation. With H-6, the old fill, these warheads did not meet any of the IM requirements. Since there was no technology available to allow these large munitions to meet the sympathetic detonation requirement, a waiver was granted to allow the improved bombs to go into service. Meanwhile, new explosives are being developed in an advanced development program to address the problem.
Waivers are granted in cases where IM improvements are not available or not affordable. However, when a waiver is granted, there is a requirement that the munition sponsor initiate some action to correct the deficiencies, and the waiver is reviewed by the OPNAV Insensitive Munitions Council annually. At these reviews, the Weapon Program Manager must justify continuing to operate under the waiver.
There should be an honest attempt made by weapon program offices to introduce the best technology available to make munitions as insensitive to heat, shock, impact, and sympathetic detonation as possible. This includes using the least sensitive explosive materials available that will meet the operational and the on-target performance requirements specified for the weapon.
The application of IM technology to Navy weapons systems is a very important consideration in ship survivability. This fact was identified in two CNO Executive Board briefings, one on fire fighting and the other on surface ship survivability in combat. The fire fighting CEB addressed the fast cook-off problems on aircraft carrier decks, while the surface ship survivability CEB addressed the sympathetic detonation problem.
Both problems are important contributors to the survivability of Navy ships. Solving the cook-off problem alone does not solve the sympathetic detonation problem. There are other energy sources that can cause sympathetic detonation. Heat is only one of these sources. One must consider all of the other possible stimuli that can initiate an unintentional explosive reaction.
The best way to avoid sympathetic detonation is to use insensitive munitions. This would minimize the probability of having the first “trigger” munition detonate. This is why the ability of an explosive material to withstand heat, shock, and impact by bullets and fragments without reacting violently is important.
With all of the attention given to reducing the sensitivity of munitions, and all the new technology developed, some weapon program managers are still reluctant to consider Insensitive Munitions technology improvements for their weapons. Rather than learning from accidents in the past, they persist in their belief that the World War II TNT-based explosives like Composition B, H-6, and Octol are the cheapest and best explosives to use.
Some persons will not be convinced otherwise until there is another aircraft carrier fire or munition train explosion to demonstrate that munitions that meet the IM cook-off requirements do not detonate in fires.
In a recent article, CAPT. Arthur Smith, U.S. Naval Reserve, Medical Corps, provided a different perspective on the use of less sensitive munitions to reduce casualties during Fleet operations:
“Unfortunately, naval warfare always will be an exceedingly dangerous activity, whether ships are operating in blue or littoral water. The potential for catastrophic casualties in ships at sea is related both to the availability of modern, accurate, and powerful ordnance and to the propensity for secondary explosions and shipboard fires…. Even projected battle-casualty estimates for separate classes of U.S. Navy ships vary…. a thread of continuity runs through all of them: Large numbers of personnel can be killed or wounded by a relatively small number of successfully targeted and delivered munitions.”94
Some sensitivity problems remain — particularly with high energy rocket motors and large warheads used for underwater munitions. These remaining problems can be solved with a continued investment in the development of IM technology. Such an investment will pay large dividends in the future.
The U.K. Ordnance Board Proceeding 42657 summarized the potential benefits of Insensitive Munitions as follows:95
- “In Wartime.
- Improved survivability of weapon systems and platforms as a result of reduced levels of damage caused by enemy strikes or credible accidents.
- Reduced casualty rates and mission losses.
- Reduced losses of ammunition as a result of enemy strikes on, or credible accidents in, magazines and storage areas.
- In Peacetime.
- Reduced risks in storage leading to better utilization of and a probable reduction in both the number and size of storage areas.
- Reduced risks in handling and more economical use of transport.
- Reduced damage from accidents and hence, relaxation of restrictions applied to achieve an acceptable level of safety.”
Thus the U.S. Navy program, called the Insensitive “Ordnance” program by RAdm. Bulkeley in 1979 and renamed the Insensitive Munitions program by Adm. Watkins in 1983, and pushed over the top by RAdm. Meyer in 1984, has gained international Attention.
Virtually all of the U.S. allies have active programs or are monitoring efforts to reduce the sensitivity of munitions without sacrificing in on-target effectiveness. Australia, Canada, France, Germany, Italy, Israel, Norway, Spain, The Netherlands, and the United Kingdom are some of the Nations that have programs to develop insensitive Plastic Bonded Explosives (PBXs), LOVA gun propellants, and insensitive minimum-smoke solid rocket propellants.
All of these Nations recognize that the use of insensitive explosive materials is one of the most important factors to consider in designing Insensitive Munitions — munitions that can be used to minimize, if not completely eliminate disasters such as that suffered by the military forces in the last quarter century.
In 1995 the U.S. Joint Requirements Oversight Council, JROC, supported the Insensitive Munitions concept and as a result an IM policy statement was included in the revised DOD Acquisition document, DODI 5000.2.96 The story about the implementation of this directive I will leave to others. Suffice it to say that, as of this day, the concept is still alive and moving forward.
Are insensitive munitions worth the extra cost? You bet they are. As shown above, the cost is cheap when one considers the alternative.
Is this an acceptable alternative?
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Picture taken on the flight deck of the USS FORESTAL (CVA-59) on 29 July 1967 – Aftermath of flight deck fire and munition explosions. U.S. Navy Photo
93Chenevey, J. V., CAPT., U.S, Navy, “New Weapons…New Tactics”, Naval Institute Proceedings, September 1994, p.108.
94Smith, Arthur M., Naval Institute Proceedings, p. 65, October 1993.
95Ordnance Board Proceeding Op. cit.
96JROC Memorandum to the Under Secretary of Defense for Acquisition and Technology, JROC 148-95 of 6 December 1995.