The prototype tanker version of the Neptune, known as the "Firestar" (N701AU ex-Buaer 145920) entered service in 1988. Conversion involved removal of the Neptune's Westinghouse J34 auxiliary turbojet engines and other military equipment, and the installation of a fire retardant delivery system consisting of a 2,000 US gallon capacity tank weighing 700 lbs and two computer controlled, electro-hydraulically actuated dispersal doors. This arrangement allows for the delivery of precisely metered flow rates from 50-700 US gallons per second. Computerized digital logic allows the pilot to select the retardant coverage level and quantity to produce the required drop pattern, resulting in drops that are continuous and uniform in density, with no overlaps or gaps. Aero Union converted three additional airframes (140963 Tanker #16, 147964 Tanker #18 and 147967 Tanker #03) bringing the total number of Firestars to four.
Close up views of the tank installation on 147964
Tanker #18 looking forward(above) and Aft(below).
Aero Union maintains a number of airframes for spares. These photos were taken at Chico, Ca.
These images graciously provided by Bill Kistler.