The solid rocket propellant [Name TBD], previously called "Propellant X" in development, was developed after the COVID-19 pandemic with initial mixing and testing in May 2023 and finalized in September 2023.
History and Purpose
After the 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 2021. 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 2022.
Goals for this formula:
- 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 (Cherry Limeade):
- 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 agent
- Added magnesium to reduce excessive slag and raise the combustion temperature due to high Al content
Formula
Mixings
| 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 |
Static Fires & Flights
| Date | Propellant | Result |
|---|---|---|
| 1/16/22 | X-2 | Lost Data & Leakage |
| 1/22/22 | X-3; X-2 (leftover motor) | 5 Motors Fired; Slight Leakage & Low Pressures due to slag |
| 2/20/22 | X4 | Slight Leakage but propellant was characterized |
| 4/11/22 | BTL1 | Burn time higher than predicted (2.5 >> 3.3) and thrust was low |
| 5/8/22 | BTL2 | Same as the static fire, same burn time, motor overperformed despite predictions |
| 7/24/22 | ML1 (Sustainer Only) | CATO of motor from burn through on HEI; no data recovered |
| 11/11/22 | ML2 | Successful static fire of both motors, HEI burn through problem fixed, precautions taken to avoid "liftoff" |
| 1/21/23 | ML4 | Successful launch with both booster and sustainer performing as expected |