O-008 New Ingredients and Propellants
To improve on the performance of currently used propellants by making the best use of the many, presently available, new energetic ingredients and propellant formulations. to provide a method for choosing the best propellants, and to know how to maximize efficiency in the search for the next generation of propellants using NIhllC's expenise and facilities to independently and objectively analyze the state of the art in new energetic materials.
The way we judge new ingredients and propellants has to be challenged. First, we must acknowledge that those in use today are not ideally suited for their task. For instance, ammonium perchlorate is bad for the environment and tends to respond badly to thennal aggression. Aluminum leaves its uail of smoke. The polymeric binders need noxious curatives, they cannot be reprocessed and they provide no energy. Ammonium nitrate has low performance, phase stability problems and is hygroscopic. New ingredients and propellants will not be perfect (immediately) either. They will be:
- new - there will need to be innovative answers to the unexpected challenges that will inevitably turn up;
- different - their drawbacks will not be the same as those from materials we know and have learnt to handle.
These facts need to be born in mind for the potential of recent advances in available materials to be realized.
It is now clear that there is no general relationship between performance and sensitivity. All propellants will be thermodynamically unstable, but it is easy to demonstrate that the bamer to reaction (the sensitiveness) is not related to the energy available from the system except within an narrow range of very similar materials. Therefore there is no reason from the sensitivity point of view why we cannot have more performance than older generations of propellants AND less sensitivity. There is not necessarily a relationship between component cost, cost/benefit, and system cost Without considering the implications of this obvious fact there is little chance new propellant ingredients will ever be used.
For the future, it can be shown that there is the possibility of making materials with far higher energy densities than those available in the past. Molecular modeling and computer added synthesis have reached a point in their maturation where they are tools that can be used for real materials not for only theoretical calculations. This will result in very high energy density materials being realized which may be very different from the highly nitrated hydrocarbon materials that we have seen in the past.
Consequently, there are materials available now that significantly improve on previous propellants. They will present different challenges in development into systems than those met on older systems. Cost and sensitivity need not be limitations to the development of the next generation of high performance propellant formulations. The biggest time saver in the development of new materials is prejudice. "It enables you to form opinions without having to get the facts".
AIAA - 32nd Aerospace Sciences Meeting and Exhibit Reno, Nevada - Jan. 10th 1994