The solid rocket propellant Deimos, previously called "Blue Voltage" in development, was developed for Project Medusa with initial mixing and testing in April 2023 and finalized in September 2023.
History and Purpose
After the successful manufacturing and launch of Phoenix in January 2023, the team created goals for the next Spaceshot rocket, Project Medusa. One of the Medusa goals are to get halfway to space (~185,000 feet). Due to the performance of Angry Goat in Project Phoenix, it was clear that a new propellant was necessary to fit the project's goals. Initial propellant formulas were developed in spring 2023, and characterization tests occurred throughout summer 2023. Lack of AP access slowed down the process in late summer 2023-mid winter 2024. Deimos is just barely pourable enough to be considered easily handled. Any more dense and it would not be pourable and would need to be packed.
Goals for this formula:
- Higher packing density than Angry Goat, but not so dense it becomes difficult to pour like Cherry Limeade
- Higher ISP than Angry Goat
Changes from previous propellant (Angry Goat):
- Use of smaller AP particles than Angry Goat
- Removed Magnesium
- Replaced HTPB with a new bonding agent to combine HTPB and Tepanol bonding agent
- Increase liquid content slightly to mitigate packed density
Formula
| Ingredient | % Mass |
|---|---|
| HTPB w/ CAO-5 & HX-752 | 11.369% |
| IDP | 5.344% |
| PDMS | .050% |
| 5 µ Al Powder | 9% |
| 200 µ Ammonium Perchlorate | 48.355% |
| 90 µ Ammonium Perchlorate | 24.178% |
| MDI | 1.704% |
Performance and Combustion Properties
Density: 0.059740 lbs/in^3
a: 0.020550 in/s
n: 0.376100
Typical ISP: 210s
Mixings
| Date | Designation | Motor(s) | Site | Result |
|---|---|---|---|---|
| 4/17/23 | Baja Blast | Characterization Motors | RT Lab | Resulted in too low pressures |
| 7/23/23 | Deimos | Characterization Motors | RT Lab | Acceptable grain; static fired and used for characterization |
| 12/5/23 | Deimos | Characterization Motors | RT Lab | Same result as 7/23/23 mix |
Static Fires & Flights
| Date | Propellant | Result |
|---|---|---|
| 7/1/23 | Baja Blast | 5 test motors integrated: 2 successful fires, 1 failure (igniter lodged itself inside the small nozzle opening), 1 didn't ignite (igniter was well at the bottom but the motor, 1 not attempted (nozzle was smaller than the failed motor, so even higher risk of repeating failure). Unfortunately, we couldn't use this data due to our pressure numbers for static fire being lower than expected (to the point that it's an issue). Likely issue was due to our load cell because hydrosttic test was successful (so no leaks). |
| 7/29 | Baja Blast | Two successful fires, but both motors had leaks, leading to substantial pressure loss. Location of leaks weren't clear until de-integration: the braces pushed the nozzle away from the carrier by a few thousandths, destroying the RTV seal. Decisions after this static fire: create new formulation for next characterization fire, and remove converging section of nozzle (make it a graphite puck). |
| 8/29 | Deimos | 5 test motors prepared, all successfully fired. Pressures are within good operating range (Nozzle A - 1779 psi, Nozzle E - 1249 psi, Nozzle I - 1283 psi, Nozzle, N - 808 psi, Nozzle S - 684 psi Interesting observations about all motors:
|