The Wright stuff

In 1902, the Wright brothers sent out a request for bids to several engine makers for an 8-hp, "vibration-free," gas-fueled engine that would weigh no more than 200 lb. No one took them up on the offer. Having successfully built a one-cylinder, 3-hp, cast-iron engine the year before to power their machine shop, the brothers decided to design and build the engine for their aircraft as well. They finished it eight weeks later with the aid of Charles Taylor, a mechanic and machinist, but without drawings. The 12-hp, four-cylinder engine weighed 170 lb, including the radiator, water and fuel tanks, and 1.5 gallon of gas. It had no throttle. The four-stroke engine always ran at about 1,000 rpm. But output could be somewhat controlled by retarding or advancing the spark timing. Other engine features included:

• Noninterchangeable components. Each was hand fitted. A piston, for example, only fit in the cylinder it was built for.
• The crankcase, cylinder water jacket, mounting lugs, and part of the intake manifold were cast as a single piece of aluminum.
• Valves were cold-rolled steel and of the poppet type. Piston suction opened the inlets and exhaust valves operated on a bicycle chain and sprocket-driven camshaft.
• Fuel dripped into the intake manifold where it was vaporized by the hot water jacket and sucked through the inlet valve and into the cylinders.
• Time between overhauls was about 12 hr.

The brothers also had to design their own propeller. They initially thought they could use information on maritime props, but found little useful data. Besides, they needed a prop with 66% efficiency, and ship props were considered acceptable if they were 50% efficient. So the brothers developed a theory of prop design in which the prop is thought of as a rotating airfoil. They designed an 8.13-ft propeller that was later found to be 66% efficient.

The Wright Brother's Flyer relied on this four-cylinder engine they built themselves. By 1910, they were using a V8 in their "Baby Gran

It Really Does Take a Rocket Scientist to Make Jet Fuel

Since 2000, rising oil prices, concerns over running out of oil, greenhouse gas emissions, and instability in the Middle East have pushed interest in biofuels - a renewable energy source derived from recently living organisms and their metabolic byproducts.

From left Centia reactor under development, biofuels systems, jet engine, fuel produced. Photo courtesy Diversified Energy Corp.

Then, last year fuel costs in the aviation industry exceeded labor costs, sending airlines looking for alternatives to petroleum-based fuel. However, traditional biodiesel fuel properties such as combustion and viscosity don't match the requirements for jet fuels. "Jet fuel travels at 25,000 to 35,000 feet where temperatures can reach −70° F, so it needs to flow better in colder temperatures," says a researcher.

The airlines may have their answer, thanks to researchers at North Carolina State University. They recently developed technology that turns fat into jet fuel. "We produce one-and-a-half billion gallons of animal fats annually, about half the amount of vegetable oil produced," says one researcher. Made from lipid-based feedstock or raw materials with a fat source, the process allows researchers to make almost any type of fuel. Feedstock typically costs 30% less than using corn or canola oil to make fuel. According to the researchers, they are not competing with the food supply, like ethanol-based fuels made from corn, but rather offering another alternative. The fuel created from Centia process burns cleaner and produces no soot or particulate matter. The process can also be used to make additives for cold-weather biodiesel fuels and, unlike most biodiesel processes, the Centia process uses its own byproducts. For example, the researchers found that the byproduct glycerol burns clean and provides energy for the fuel-making process.

The technology, called Centia and licensed by Diversified Energy Corp., Gilbert, AZ, is 100 percent green, using no petroleum-derived products. The Centia process has four steps - the first two are always the same with the last two changing based on the type of fuel. First, the engineers use high-temperatures and high-water pressures to strip off the free-fatty acids from the accumulated feedstock of oils and fats. Next, the fatty acids are placed in a reactor for the removal of carbon dioxide (decarbonoxylation). Depending on the type of feedstock, scientists are left with alkanes, or straight-chain hydrocarbons of either 15 or 17 carbon atoms. The last two steps consist of the breaking up the straight chains into molecules with branches, making them more compact and charging their chemical and physical characteristics.