The Air Force Office of Scientific Research (AFOSR) and NASA recently launched the first test rocket using an environmentally-friendly, safe propellant comprising nanoscale aluminum powder and water ice (ALICE).

The ALICE flight-vehicle assembled on the launch rail. It consists of an all-carbon-fiber, minimum-diameter high-power rocketry kit. (Credit: Dr. Steven F. Son, Purdue University) Click to enlarge.

ALICE has the consistency of toothpaste when made. It can be fit into molds and then cooled to -30 °C 24 hours before flight. The propellant has a high burn rate and achieved a maximum thrust of 650 pounds during this test.

Using ALICE as fuel, a nine-foot rocket soared to a height of 1,300 feet over Purdue University’s Scholer farms in Indiana earlier this month. ALICE is generating excitement among researchers because this energetic propellant has the potential to replace some liquid or solid propellants. When it is optimized, it could have a higher performance than conventional propellants.

Penn State and Purdue University researchers presented a paper on an investigation of ALICE propellants at the 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit earlier this month in Denver, Colorado.

They found that the pressure exponent for ALICE was 0.73, which is approximately a factor of two larger than Al/water mixtures. Three sizes rocket motors ranging from internal diameters of 0.75 to 3-in. ALICE propellants successfully ignited and combusted in three different lab-scale rocket motors, generating thrust levels above 223 lbf for expansion ratios of 10 and center-perforated grain configurations (3-in length). For a 3-in motor, combustion efficiency was around 70%, while the specific impulse efficiency was 64%.

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