After four and a half years of study, discussion, testing, and demonstration, the Tripoli Board of Directors has unanimously approved the use of bi-propellant liquid motors at Tripoli-sanctioned launches, effective January 1, 2026.
The updated Tripoli Unified Safety Code (TUSC) will be posted next week, but the following summarizes key provisions:
Approved Liquid Motor Configurations
1. Oxidizer
2. Fuel
-
Isopropyl alcohol (isopropanol)
-
Ethyl alcohol (ethanol)
-
Mixtures containing at least 70% isopropanol or ethanol by volume. These mixtures may include other hydrocarbons, dissolved solids, gasoline, or water, provided they are not hypergolic or pyrophoric.
System Requirements
Flight Tanks
-
Constructed from aluminum, composite, or composite-overwrapped aluminum shells.
-
Pressurized only by the vapor pressure of nitrous oxide.
-
Must passively depressurize in the event of a remote dump system failure.
Remote Operations
Combustion Chambers
-
Made of non-ferrous ductile metals such as 6061 aluminum alloy.
-
Single-piece chambers may use injectors, nozzles, and nozzle throat inserts of graphite, composite, or non-ferrous metals.
-
Multi-piece chambers may use appropriate materials for nozzles, injector bells, plates, and throats rated for expected pressures and temperatures.
Oxidizer and Fuel Systems
-
All nitrous oxide components upstream of the remote fill valve must be oxidizer-compatible, clean, and rated above maximum expected pressure.
-
Fuel system components must be compatible with the chosen fuel.
-
No active throttle control is permitted during flight.
Further details will be included when the updated Tripoli Unified Safety Code (TUSC) is released.
Questions may be directed to the Tripoli Forums (Rocket Motor section).
Special thanks to the Tripoli Research Committee, the testing and demonstration participants, and to the organizers of BALLS 32 and AirFest 31 for hosting Tripoli’s liquid motor evaluations.
Bob Brown
President, Tripoli Rocketry Association