spaceshot 2024
MISSION ARTICLES
Following the successful launch and recovery of Aftershock II, the second of the USC Rocket Propulsion Laboratory’s Aftershock-series solid-motor vehicles, data from the on-board avionics unit was collected and used to reconstruct its flight path. After an internal review of the raw data, advanced filtering methods and reconstruction simulations were used to determine and validate an apogee of 470,400 ft ± 27,300 ft (3σ), breaking the amateur altitude record of 380,000 ft, previously set by CSXT’s GoFast rocket. USCRPL also determined a maximum speed of 5,283 ft/s, breaking the record of 5,019 ft/s also set by the GoFast rocket. This establishes Aftershock II as the fastest and highest amateur rocket of all-time.
Highest altitude achieved (Student + AMateur Rocketry)
Previous student rocketry record was held by ‘Traveler IV’ when it reached 339,800 ft (104 km). Previous amateur rocketry record was set in 2004 when ‘GoFast’ reached 385,800 ft (117.6 km). Aftershock II shattered this record by reaching 470,400 ft (143.3 km), which is nearly at the FAA limit for amateur rocketry at 492,000 ft (150.0 km).
Fastest Velocity achieved (student + Amateur Rocketry)
Previous student rocketry record was held by ‘Traveler IV’ when it reached 4,966 ft/s (1,513 m/s). Previous amateur rocketry record was set in 2004 when ‘GoFast’ reached 5,019 ft/s (1,530 m/s). Aftershock II broke both records by achieving 5,283 ft/s (1,610 m/s).
NEWS ARTICLES
TECHNICAL DETAILS
| Apogee | 470,400 ft (144,300 m) |
| Max Velocity | 5,283 ft/s (1,610 m/s) |
| Motor Designation | GEM8-R4000 |
| Max Thrust | 4,220 lbf (18,771 N) |
| Burn Time | 16.3 s |
| Total Impulse | 51,529 lbf-s (229,212 N-s) | Total Vehicle Mass | 322 lbm (146 kg) | Dry Mass | 127 lbm (57 kg) |
| Propellant Mass | 200 lbm (90 kg) |
*All Values are in Vacuum Performance
Structures
Case |
| Built entirely in-house, this structure serves both as the combustion pressure vessel and the airframe, making Aftershock II a minimum diameter rocket. Featuring USCRPL’s signature filament-wound carbon epoxy design with co-bonded insulation, this is the longest case the club has ever flown. A body length of over 110 inches gives space for the organization's biggest motor, making this the largest-ever amateur carbon-case motor to fly with solid propellant. Finally, in response to heavy erosion seen on Traveler IV’s trailblazing flight, Aftershock II employed an in-house developed silicone-based ablative thermal-protection system (TPS). |
Nosecone |
| Another one of USCRPL’s crown developments, an ablative cork TPS on the conical nosecone ensured the protection of avionics components from heat and structural failure. In addition to the case, the nosecone brings the total length of the vehicle to 13 feet. By bonding together fiberglass, cork, and metal in all the right ways, this structure withstood immense heat to give way to the vehicle’s recovery system at apogee. |
Nozzle |
| The nozzle is comprised of heat-resistant carbon phenolic prepreg and a graphite throat. These materials were selected to be as light as possible while maintaining their geometries over the course of the firing. Excessive erosion ruins the nozzle efficiency, but both graphite and carbon phenolic resisted the intense forces of the supersonic gases propelling the rocket. Bonded together with state-of-the-art metal retention components, this is the club’s lightest nozzle to date. |
Fins |
| Similar to the case, the fins on Traveler IV saw immense erosion. Aftershock II utilized USCRPL’s standard four carbon fiber fins, pressed to a precise thickness and held on with carbon fiber that reaches from the edge of each fin to the next. Additionally, this vehicle featured cutting-edge metal leading edges on the fins to ensure that their critical aerodynamic profile was not compromised over the course of flight. Tested on a previous vehicle, this was the first time this technology was used on a spaceshot and highly improved Aftershock II's ability to reach its designed altitude. |
PRopulsion
Propellant |
| USCRPL mixes and casts a custom ammonium perchlorate composite propellant (APCP) to propel its rockets. Using a formula developed by students in the club, each propellant grain is made by USCRPL starting from raw chemicals, setting the club apart from many other collegiate rocketry teams. With nearly 200 pounds of propellant, Aftershock's motor, comprised mainly of BATES-type propellant grains, will be the largest built by USCRPL. |
Avionics
Our flight computer HAMSTER consists of 5 PCBs we've designed and laid up in house.
Power Board |
| The first is our power board which delegated power throughout our system and bypassed the protective circuitry of our battery packs to allow HAMSTER to run significantly longer. |
Connector Board |
| The second is our connector board which interfaced with all of our 3rd party commercial off the shelf (COTS) components. |
Lightspeed Rangefinder |
| The third is our 'Lightspeed Rangefinder' transponder. It performed radio-based distance measurements between multiple points on the ground with the rocket as it ascended, allowing us to gather critical altitude information where systems like GPSs would lock out due to COCOM (read this for the original thesis paper: (https://engrxiv.org/preprint/view/1655/4292). |
Guidestar GNSS Reciever |
| The fourth is an in-house developed 'Guidestar' GNSS reciever, which used the existing GNSS systems to locate the rocket's position and altitude. Since it is built in-house it is not subject to the same CoCom limitations as typical commercial units. |
Sensor Board |
| Fifth on our stack is our sensor board which, as the name implies, gathered data on sensors (acceleration, temperature, barometric, and GPS). It also executed our flight software. |
Integrator Board |
| Finally we have our integrator board that performs sensor fusion on magnetometer, gyroscopic, and acceleration data. It takes this information in the inertial frame and uses it for live integration to determine parameters such as burnout velocity. |
Recovery
Single-deployment System |
| A single deployment recovery system was used to ensure safe landing at roughly 65 ft/sec. The nosecone was ejected at apogee using a punctured CO2 canister. The nosecone and airframe separation passively deployed the parachute, and inflation began once it entered the atmosphere. In addition to a robust parachute, a 360 camera and GPS were also connected to the tether for post-flight footage and recovery operations. |