“LightingThe Candle” Of A Wax Fueled Rocket

Since 2001, NASA’s Ames Research Center has been testing a new rocket fuel made from–believe it or not–paraffin candle wax. Arif Karabeyoglu, who developed the theory behind paraffin-based rocket fuels, is currently a research associate at Stanford University’s Aero Fluid Mechanics Lab. He figured out a way to make paraffin burn three times faster than had ever been achieved before–fast enough to serve as rocket fuel. In his design, the paraffin burns in the presence of pure oxygen gas. This alone causes it to burn much hotter than it does in air, which is only about 21% oxygen. That much had been done before; Karabeyoglu’s new innovation was to blow the oxygen past the melted surface of the paraffin fast enough to “whip up” this surface, like the ocean’s choppy surface on a windy day. The “sea spray” of paraffin droplets that this kicks up burns very rapidly, tripling the combustion rate of the fuel. More than 40 test firings by the Stanford-Ames collaborative project have shown that the idea works as advertised.

Two advantages of paraffin rockets over conventional solid fuel rockets would be safety and environmental impact. The new paraffin-based fuel is less expensive, non-toxic and non-hazardous. In flight, “A hybrid rocket equivalent to the Space Shuttle’s solid rockets would be about the same diameter, but would be somewhat longer,” said Stanford University Professor Brian Cantwell. “Hybrid rockets, using the paraffin-based fuel, can be throttled over a wide range, including shut-down and restart. That’s one reason why they could be considered as possible replacements for the Shuttle’s current solid rocket boosters that cannot be shut off after they are lit.” Also, the by-products of combustion from the new paraffin fuel are carbon dioxide and water. In contrast, the Solid Rocket Boosters (SRBs) on the Space Shuttle produce 68 tons of hydrochloric acid per launch – which NASA insisted ten years ago doesn’t harm the ozone layer.