1. High Temperature Aging Test Data for Double Base Propellant using an Advanced Stabilizer
May 15, 2018

2. Project Background
This project is a Phase II.5 SBIR project to develop a double base nitroglycerine/nitrocellulose propellant with high temperature ageing capability superior to the Mechanite 19 propellant currently in use in the F-18 DCAD/PAD devices
Chemring currently manufactures and supplies propellant grains to NACES seat manufacturer Martin Baker
Alternative propellant investigation initiated after a premature activation occurred at China Lake
Current operational life in an F-18 deployed at China Lake is 2 years
Program goal is to recover the operational life capability for a minimum of 4 years
ASRC/ASTS is partnered with BAE/Radford to develop the improved propellant in their production facility

3. Phase II Results
The Phase II SBIR evaluated several potential stabilizing candidates with N-Methyl-P-Nitroaniline (MNA) showing the potential to double the service life compared to the fielded 2-Nitrodiphenylamine (2-NDPA)
Increasing the stabilizer concentration also showed the potential to further increase the shelf life

4. Phase II.5 Plan
The propellant formulation used as a baseline is the AA-17 2-NDPA stabilized double base propellant developed by the Navy and Radford in 2010
The new propellants would replace the 2-NDPA in the AA-17 formulation with MNA at concentrations of 2, 4, 6, 8, and 10%
All formulations would be evaluated for processing, safety properties, burn rate, and stability
Acceptable propellants would be subjected to a 2 month 160°F high temperature short term (HTST) ageing study
Two propellant formulations down selected from the HTST ageing study are to be mixed in the Radford production facility
Propellant samples are to be placed in three ovens on and subjected to a variable 24 hour temperature profile that simulates the China Lake summer F-18 cockpit temperature profile for a maximum of 1 year
Mechanite 19 samples are also included in the ageing study
Upon completion of the China Lake ageing study the best formulation will be processed into propellant cartridges for motor testing by the Navy

5. China Lake Thermal Profile
Oven Temperature vs. Time
Peak operating temperature is 170°F
Average temperature is approximately 118 °F

6. Processing Evaluations
Mixing and processing trials eliminated the 10% MNA formulation as it was not able to be rolled
Burn rate additive mixing was evaluated and optimized to be added dry as a composite mixture
Strand burn rate results obtained were comparable to 2010 AA-17 propellant historical data

7. HTST Ageing Study Plan
1 g samples from each propellant formulation (4” X 5” sheet) individually wrapped in two layers of aluminum foil and placed into an aging oven at 160°F (71°C) for 57 days on 10/24/17
Samples removed from the oven on one week intervals
Baseline Propellant Testing
Burning Rate
Tensile Properties
Chemical Composition
Stability (German Test and Taliani)
Limited Safety Testing
Aged Propellant Testing
% MNA
Stability (Taliani)
Chemical Composition (End of Aging Only)
Burning Rate (End of Aging Only)

8. HTST Ageing Study MNA Depletion Results
2nd order polynomial regression analysis of the data models the data with at least a minimum .94 correlation
Regression analysis suggests that the 6% MNA formulation provides the longest time until the MNA is depleted
The data at 50 days for all formulations is suspect as it is inconsistent with polynomial trend line and was less than or stayed the same for all formulations as the data at 57 days
Retesting was not possible due to limited samples

9. HTST Ageing Study Stability Test Results
Taliani values increases for all concentrations slightly over time but does not appear to be following any pattern
The 6 & 8% MNA formulations have more scatter in their data
Limit for unacceptable ageing is 0.8 so all formulations remained stable over the duration of the ageing study
The German stability test done at the start and end of the study showed acceptable results

10. HTST Aged Propellant Burn Rate Results
Burn rate decreased as the MNA concentration increased suggesting an interaction of the burn rate additives with the MNA stabilizer
Burn rate for all the aged formulations increased compared to the baseline burn rates
The largest difference was at psi but decreased to the smallest percentage at 4500 psi
One possible explanation is the MNA depresses the burn rate and as the MNA is depleted it has less of an effect

11. Baseline Mechanical Properties
Stress increases 26% and strain decreases 56% for the 8% MNA formulations
Results were expected as the MNA concentration increased the corresponding Triacetin plastizer concentration decreases in each formulation

12. Baseline Safety Properties
DSC tests showed a very slight decrease in temperature as MNA increased for the 6 & 8% formulations
NOL Large Scale GAP Test (LSGT) showed a positive detonation result for the 2% MNA formulation
The 2% MNA formulation was eliminated from further study based on this result
NOL Large Scale GAP Test results for the other formulations was negative with the response decreasing with increasing MNA concentration
The Small Scale Burning Test showed negative results with burning only for all formulations
The 48 Hour Stability Test for all formulations was stable with no decomposition

13. HTST Ageing Study Summary
Propellant samples for 4 formulations with 2,4,6, & 8% MNA were aged for 57 day at 160°F
Increasing the MNA concentration had the effect of decreasing the propellant burn rate
The propellant burn rate for all formulations slightly increased at the end of the ageing study for unknown reasons
The 2% MNA formulation was eliminated from further study based on a positive NOL Safety test result
The 4 & 6% MNA formulations were down selected to be evaluated in the China Lake ageing study providing the best opportunity to extend the service life of the propellant with burn rate properties similar to the 2-NDPA AA-17 propellant developed in 2010 by Radford
The two formulations were mixed on 4/7/18
The China Lake ageing study was started on 4/11/18

14. Questions