Joint Services Environmental Management (JSEM) Conference

Transcription

1 Research, Development & Engineering Command Lead-Free Ballistic Modifier for Rocket Motor Propellants Joint Services Environmental Management (JSEM) Conference 24 May 2007 Darren Thompson Propulsion Technology Function Propulsion & Structures Directorate US Army Aviation & Missile RD&E Center

2 Problem Statement Current inventory of Tactical Missile propellants that utilize lead compounds to modify ballistic properties Tactical Missile use both composite and double-base propellants Composite propellants-hellfire,javelin,tow Double-base propellants-mark 66 Hellfire TOW Javelin 2.75 Why use lead ballistic modifiers? Controls burn rate Imparts plateau burning characteristics Reduces sensitivity of propellant to temperature

3 Problem Statement Lead health effects: Toxicity issues and regulatory constraints Permissible Exposure Limit (PEL) of 50 ug/m3 and action level of 30 ug/m 3 (29 CFR ) Worker and soldier exposure issues from propellant production and use (training, testing, combat) No lead-free alternative fully demonstrated (dem/val level testing) with castable or extruded propellants

4 History of the Development Army Lead-Free Solid Rocket Propellants Aviation and Missile Research, Development and Engineering Center (AMRDEC) has been formulating lead free propellants for evaluation since the early 1990 s AMRDEC participated with Navy/Indian Head, Maryland in a joint SERDP program called Green Missile from that investigated lead free formulations in minimum smoke propellants The results of Green Missile program have been transitioned to the present EQT Lead-Free Solid Propellant Project

5 Current Efforts Research, Development and Engineering Command (RDECOM) has been funding AMRDEC in the development of a castable lead-free propellant through the Environmental Quality Technology (EQT) program since 2005 ESTCP recently funded AMRDEC in a joint program with ATK-Radford and Navy/Indian Head for the development of an extruded lead-free propellant

6 Castable vs. Extrudable Propellants Why is it necessary to have a lead-free propellant in a castable and an extrudable version? Extrudable propellants can be made much cheaper than castable propellants However, extrudable propellant technology is limited to propellant grains that are less than six inches in diameter Therefore it is necessary to have lead-free formulations using both technologies to address all the weapon systems in the Army inventory

7 Propellant Requirements The chief reason the development of reduced toxicity propellants is such a time consuming process is that the propellant is required to meet many requirements simultaneously Requirements that often are mutually exclusive Advancements made in earlier years are often nullified by changes in propellant requirements in later years The following is a list of typical requirements (this list is not exhaustive): Performance Signature Sensitivity Aging Toxicity

8 Propellant Formulation Process Selection of Ingredients As part of the EQT and ESTCP projects, the Center for Health Promotion and Preventative Medicine (CHPPM) provides support in evaluating the toxicity of potential lead replacements Involving CHPPM early in development of the formulation ensures a successful toxicity clearance by CHPPM at the end of the acquisition process Laboratory Evaluation Once new ingredients are selected a pint size mix is made of the propellant formulation to evaluate properties: Processability Mechanical Properties Ballistic Properties Sensitivity to External Stimuli

9 Typical CHPPM Environmental Health Assessment = Likely Benign = Possible Problem = Probable Problem = Unknown Compound Persistence Transport Combustion Products Human Health Ecologic Data Gaps A B C D E F G H I J K L M

10 Propellant Formulation Process (cont d) Laboratory Evaluation (cont d) If the propellant goals are not met the formulation is altered and tested again and this step is continued until all the goals are met Small Scale Motor Evaluation The propellant mix is scaled up to a gallon mixer Often properties change as the mix size changes Therefore propellant properties are evaluated again and changes in the formulation are made to compensate Small motors (less than 200 grams of propellant) using the formulation are made to evaluate the ballistic properties on a larger scale by conducting static motor tests If the results meet ballistic property goals then development moves to the next phase If not, the formulation is altered until all property goals are met

11 Propellant Formulation Process (cont d) Analog Scale Motor Evaluation Propellant mix is scaled up to five gallon mixer Properties may have changed from the one gallon mixer results as the batch is scaled up Therefore propellant properties are evaluated again and changes in the formulation are made to compensate Analog motors (approx. 10 lbs. of propellant) using the formulation are made to evaluate the ballistic properties on a larger scale by conducting static motor tests If the results meet ballistic property goals then development moves to the next phase If not, the formulation is altered until all property goals are met

12 Formulation Transition At the conclusion of analog motor testing the formulation will have increased in technological maturity from a TRL 2 to a TRL6 Since the analog motor uses as much propellant as many fielded tactical missiles, PMs are often receptive to further developing the propellants that have reached this TRL Development after this point may include scaling up to larger batch sizes (20 gallon, 50 gallon, etc.), flight testing and final qualification Final qualification may require as many as 200 full scale rocket motors and cost on the order of millions of dollars

13 Transition from EQT Program An intermediate program step that is useful in the development beyond a propellant beyond a TRL level of 6 or 7 is the Advanced Technology Objective (ATO) ATOs are technology demonstrations that are directed at the development at a sub-system; so in the case of the development of the propellant an ATO would be directed at the development of a propulsion system that would use a particular propellant technology ATOs are useful for developing propellant technologies in situations in which a PM has not been found that would fund the full qualification of a novel propellant The ATO is useful in keeping the development of a particular propellant alive until a PM is willing buy-in to its qualification

14 Points of Contact Project Lead, AMRDEC Mr. Darren Thompson Navy/Indian Head Mr. Stephen Stiles ATK Mr. Jim Wedwick Environmental Acquisition & Logistics Sustainment Program (EALSP) Director Ms. Maryalice Miller, RDECOM ESTCP Program Manager Weapon Systems and Platforms Mr. Charles Pellerin Hughes Associates Mr. William Ruppert