Darracq—2 to 14 cylinders, water cooled; 30 to 200 horse power; weight of smallest 100 pounds.
Wright—4-cylinder, water-cooled; 25 horse power; weight 200 pounds.
Antoinette—8 and 16-cylinder, water-cooled; 50 and 100 horse power; weight 250 and 500 pounds.
E. N. V.—8-cylinder, water-cooled; from 30 to 80 horse power, according to bore of cylinder; weight 150 to 400 pounds.
Curtiss—8-cylinder, water-cooled; 60 horse power; weight 300 pounds.
Average Weight Per Horse Power.
It will be noticed that the Gnome motor is unusually light, being about three pounds to the horse power produced, as opposed to an average of 4 1/2 pounds per horse power in other makes. This result is secured by the elimination of the fly-wheel, the engine itself revolving, thus obtaining the same effect that would be produced by a fly-wheel. The Farcot is even lighter, being considerably less than three pounds per horse power, which is the nearest approach to the long-sought engine equipment that will make possible a complete flying machine the total weight of which will not exceed one pound per square foot of area.
How Lightness Is Secured.
Thus far foreign manufacturers are ahead of Americans in the production of light-weight aerial motors, as is evidenced by the Gnome and Farcot engines, both of which are of French make. Extreme lightness is made possible by the use of fine, specially prepared steel for the cylinders, thus permitting them to be much thinner than if ordinary forms of steel were used. Another big saving in weight is made by substituting what are known as "auto lubricating" alloys for bearings. These alloys are made of a combination of aluminum and magnesium.
Still further gains are made in the use of alloy steel tubing instead of solid rods, and also by the paring away of material wherever it can be done without sacrificing strength. This plan, with the exclusive use of the best grades of steel, regardless of cost, makes possible a marked reduction in weight.