Although the idea of developing an enlarged version of the Dove was conceived in 1945, detailed design work did not get underway until 1949. Designed from the outset to be a simple, rugged aircraft capable of economic operation from the most rudimentary of airstrips, the Heron had no complicated hydraulics, its engines were ungeared and not supercharged, and initially it even featured fixed landing gear. Performance, even of the later Heron 2 with retractable gear, was said to be “leisurely”, due to a lack of engine power. This led to several re-engining programmes, most notably that by Riley Aeronautics which had also offered a similar programme for the Dove.
First flight: 10 May 50 (c/n 10903, G-ALZL)
Production: 149 in the UK, comprising 8 at Hatfield and 141 at Hawarden; and 1 in Canada by Saunders at Gimli, MB.
First delivery: 1 Apr 52, to New Zealand National Airways (c/n 14001, ZK-AYV)
Last delivery: 5 Jun 64, to Falcks Flyvetjeneste (c/n 14147, OY-AFO)
Variants: Heron 1 - initial production version powered by 4 De Havilland Gipsy Queen 30 Mk.2, with fixed undercarriage and accommodation for up to 17 passengers (52 built, including the eight at Hatfield);
Heron 2 - developed version with retractable gear (97 built). Higher weight versions of both were also produced, designated Heron 1B and Heron 2B respectively.
ST-28 - new-build version of ST-27 optimised for US market with detail improvements (1 built, first flight 18 Jul 74).
Conversions: Riley Turbo Skyliner - Heron 2 re-engined with Lycoming IO-540-G1A5 turbo-supercharged six-cylinder engines (unknown number converted at Fort Lauderdale, FL, and from kits by Connellan Airways at Alice Springs, NT, and the Sri Lanka AF at Colombo-Katunayake in 1972);
Prinair Heron - Heron 2 re-engined by Puerto Rico International Airlines with Continental IO-520s; one was further modified by addition of a 17ft. fuselage ‘stretch’;
Tawron - Heron 1 re-engined with Continental IO-470Ds by Shin Meiwa for Toa Airways (6 converted);
ST-27 - stretched, re-engined Heron 2 with accommodation for up to 23 passengers, powered by 2 United Aircraft PT-6A-27 turboprops (12 conversions, comprising 1 by Atlantic Aviation at Dorval, QC and the remaining 11 by Saunders at Gimli, MB; first flight 28 May 69).
Comments