TO describe a new high-antiknock fuel that is well suited for the modern high-output aircraft engine and potentially available in large quantities, is the object of this paper. The high-octane blending agent used is isopropyl ether.
Results of full-scale multicylinder engine tests with this material and iso-octane each blended with aviation gasoline to give a 100-octane fuel with 3 cc. of tetraethyl lead, and with iso-octane blended with aviation gasoline to give a 92-octane fuel with 3 cc. of tetraethyl lead, indicate that:
Minimum specific fuel consumption of the isopropyl-ether 100-octane blend is lower under cruising conditions than the 92-octane, but higher than the 100-octane, iso-octane blend; the lower economy of isopropyl ether may be overcome by going above 100-octane number; and the 100-octane blends of isopropyl ether and iso-octane are equal in power output and consumption under high-power conditions.
The material easily meets water-tolerance specifications showing only slight solubility in water. Low gum content and satisfactory resistance to oxidation of these blends indicate the storage stability proved by storage tests.
Single-cylinder engine tests show that isopropyl ether has a blending value slightly superior to technical iso-octane and less lead is necessary to meet a given octane number for equivalent percentage concentrations.
A recent survey of the supply of propylene, the raw material, indicates enough of it available to produce 850,000,000 gal. per year of 100-octane fuel - more than sufficient even in a National emergency.