Northrop Delta / RT-1
While the Gamma was being developed, Northrop was working on a nine-seat transport, which was basically a new fuselage married to Gamma wings. Unfortunately for Northrop, the US 1926 Air Commerce Act was amended to prohibit the use of single-engine aircraft for carrying passengers by night, or over rough terrain where emergency landings could not be made. Consequently, airline use for its intended role was nonexistent in the USA, although three had been sold before the new regulation was announced. Eight others were used as executive transports, and one was bought by Swedish AB Aerotransport, which subsequently acquired a second.
The US Coast Guard operated a Delta under the designation RT-1, as the Secretary of the Treasury's personal aircraft.
The last Delta was supplied to Canada as a pattern aircraft for assembly in that country by Canadian Vickers, who built 20 of various marks with both wheel and float landing gear. Deltas were flown with various engines, including the 529kW and 548kW Wright SR-1820, 485kW, 492kW and 522kW Pratt & Whitney Hornets.
Northrop Delta 1D NC13777 s/n 28