The solid rocket propellant [Name TBD] Deimos, previously called "Propellant XBlue Voltage" in development, was developed after the COVID-19 pandemic for Project Medusa with initial mixing and testing in May April 2023 and finalized in September 2023.
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History and Purpose
After the successful manufacturing and launch of Hermes III in February 2020, it was clear that our previous propellant, Cherry Limeade, did not fit the needs of our team. So a new propellant formula began to be developed. Unfortunately, the COVID-19 pandemic ceased work on the propellant for the rest of 2020, until it was picked up again in January 2021Phoenix 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 that first month and parameters to be tested were identified by the end of spring 2021. Due to a lack of mixing space access as a result of the pandemic, the development of the propellant did not begin until November 2021, concluding with the final characterization fire in February 2022. First used in flight on the Pheonix Test Launch in May 2022spring 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
- Experiment with increased aluminum levels using 5-micron aluminum instead of 30-micron
- Make a propellant that is easy to handle when mixing and handling to increase density
- Become a platform for future propellant formulas to be used on a space shot attempt eventually
Changes from previous propellant (
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Angry Goat):
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- Use of smaller AP particles than Angry Goat
- Removed Magnesium
- Replaced HTPB with a new bonding agent to combine
- Removed Castor Oil and Triton X100, since the propellant was already viscous
- Changed from 200-micron AP to 400-micron AP as the large particle in packing to increase pourability
- Replaced HTPB with an added bonding agent to separate HTPB and Tepanol bonding agentAdded magnesium to reduce excessive slag and raise the combustion temperature due to high Al content
- Increase liquid content slightly to mitigate packed density
Formula
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| Ingredient |
|---|
| Date | Designation | Motor(s) | Site | Result |
|---|---|---|---|---|
| 11/14/21 | X-1 | Characterization Motors | Firefly Lab | Density too low, grains rejected |
| 1/4/22 | X-2 | Characterization Motors | Firefly Lab | Good density achieved with a modified procedure and formula |
| 1/17/22 | X-3 | Characterization Motors | Firefly Lab | Good density achieved, virtually identical to the last mix |
| 2/1/22 | X-4 | Characterization Motors | Firefly Lab | Good density, textbook mix except mandrel got a bit stuck |
| 3/29/22 | BTL1 | Booster Test Launch SF | Firefly Lab | Even better density due to a larger mixing bowl, tepanol may not have been mixed correctly |
| 4/26/22 | BTL2 | Booster Test Launch Flight | Firefly Lab | Fixed tepanol issue, very similar to static fire motor as designed |
| 6/15/22 | ML1 | Main Launch Static Fire | Firefly Lab | Much denser than previous mixes, the booster mandrel could not be removed |
| 7/9/22 | BML1 | Booster Main Launch Remix | Firefly Lab | Mandrel still didn't come out, switching to an alternate design where the central core doesn't go all the way through |
| 10/8/22 | ML2 | Main Launch Static Fire | Firefly Lab | The mandrel was successfully removed this time, density was acceptable |
| 11/21/22 | ML3 | Main Launch Flight | 17-101 | Wrong Value of MDI added, Scrapped mix |
| 12/4/22 | ML4 | Main Launch Flight | 17-101 | Good density |
| % 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
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| 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:
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