Combustion is a disorganized molecular process. Its product molecules fly around vigorously at random, as hot gas. A heat engine, usually a complex and inefficient piece of machinery, can extract a little of this energy as useful work.

Daedalus is now seeking a better way. In a common model of enzyme action, the reagent molecules sit neatly on the active site of the enzyme, in just the right positions to react. When the last bond of the product molecule is formed, the molecule changes shape, no longer fits, and springs off the enzyme surface, leaving the site free for further reagent molecules. This spring, says Daedalus, must represent a large part of the energy of the reaction. And it is not liberated as heat, but as molecular velocity in a specific direction. Only later, as the product molecule slams into others nearby, is it degraded to heat.

So DREADCO chemists are seeking the equivalent phenomenon on surfaces that catalyse combustion. A well-ordered surface might well fire off the final CO2or H2O molecules vigorously and directedly, as they take their final shape and cease to fit the surface. In a low-density gas environment, they would travel some distance before hitting any other molecule. The catalytic surface would feel the full reaction force of their departure.

The obvious application is to aircraft propulsion. So the researchers are taking their most promising catalytic materials, and vacuum-evaporating them onto model gliders. The evaporation directions are cunningly chosen so that the deposited catalytic crystallites acquire exactly the right orientation to the local wing surface. Each glider is then being flown in a dilute, non-explosive mixture of air with a fuel gas, such as hydrogen or ethylene. With the right catalyst, the products of surface combustion will not be disengaged as hot gas, but will be ejected directionally downwards and backwards. Their reaction will give lift and thrust. In its novel atmosphere, the glider will speed and soar indefinitely.

A realistic aircraft, however, has to fly in pure air on liquid fuel. The fuel will be pumped through porous regions on the catalytic surfaces, to diffuse over them as a monolayer. The new craft will be propelled by its whole surface. It will be utterly silent, free of heavy and expensive engines, and powered with greater than Carnot efficiency. It will transform aviation. Sadly, its owners will have to forego the usual tasteless painted colour-schemes.