de Havilland Heron
|de Havilland DH.114 Heron 2 of Cambrian Airways at Manchester Airport operating a scheduled service in April 1958|
|First flight||10 May 1950|
|Primary users||Garuda Indonesian Airways; Prinair
|Developed from||DH.104 Dove|
The de Havilland DH.114 Heron was a small propeller-driven British airliner that first flew on 10 May 1950. It was a development of the twin-engine de Havilland Dove, with a stretched fuselage and two more engines. It was designed as a rugged, conventional low-wing monoplane with tricycle undercarriage that could be used on regional and commuter routes. 150 were built, exported to around 30 countries. Herons later formed the basis for various conversions, such as the Riley Turbo Skyliner and the Saunders ST-27 and ST-28.
Design and development
Immediately after the Second World War, the aircraft manufacturer de Havilland developed the DH.104 Dove, a small two-engined passenger aircraft intended as a replacement for the earlier Dragon Rapide, and which soon proved to be successful. As a further development, the company basically enlarged the Dove; the fuselage was lengthened to make room for more passengers or freight, and the wingspan was increased to make room for two more engines. The Heron was of all-metal construction, and was laid out as a conventional design; the resulting aircraft could use many of the parts originally designed for the Dove, thus simplifying logistics for airlines using both types.
The emphasis was on rugged simplicity to produce an economical aircraft for short to medium stage routes in isolated and remote areas which did not possess modern airports. The Heron was designed with a fixed undercarriage and reliable ungeared unsupercharged Gipsy Queen 30 engines.
The Heron prototype registered to the de Havilland Aircraft Company, Hatfield, UK as G-ALZL undertook its first flight with Geoffrey Pike at the controls on 10 May 1950. The aircraft was unpainted at the time, and after 100 hours of testing was introduced to the public on 8 September 1950 at the Farnborough Airshow, still glistening in its polished metal state. By November, the prototype had received its formal British Certificate of Airworthiness and had flown to Khartoum and Nairobi for tropical trials.
The prototype was then painted and fitted out as a company demonstrator, and was tried by British European Airways in 1951 on their Scottish routes. Following the successful completion of the prototype trials as a regional airliner, series production of the Heron began. The first deliveries were to NAC, the New Zealand National Airways Corporation (later part of Air New Zealand).
Basic price for a new Heron in 1960 was around £60,000 minus radio.
The first Heron, Series 1A suffered deficiencies, as NAC soon discovered. Firstly, the aircraft was generally underpowered. Its quite heavy engines (weighing about 882 lb/400 kg each), had an output of only 250 hp (190 kW) each. By comparison, later modifications or rebuilt aircraft had as much as 50% more power (in the case of the Saunders ST-27). Unlike the Dove, the Heron came with a fixed undercarriage and no nosewheel steering, which simplified maintenance, but reduced top speed. Secondly the lightweight aluminium alloy wingspars were prone to constant cracking due to the heavy loading on the wing caused by the overweight engines and rough landings on non paved runways at the time. NAC resolved this by replacing the aluminium spars with heavier steel spars, reducing the performance of the Heron Series 1A (re-classified 1B) to uneconomic levels for the services required of them in New Zealand. NAC disposed of them in 1957.
After 51 Series 1 aircraft had been built, production switched to the Series 2, featuring retractable landing gear, which reduced drag and fuel consumption, and increased the top speed marginally. The 2A was the equivalent of the 1A, the basic passenger aircraft while the 1B and its successor the 2B had higher maximum takeoff weight, the 2C featured fully feathering propellers, the Heron 2D had an even higher maximum takeoff weight, while the Heron 2E was a VIP version.
In service, the Heron was generally well received by flight crews and passengers who appreciated the additional safety factor of the four engines. At a time when smaller airliners were still rare in isolated and remote regions, the DH.114 could provide reliable and comfortable service with seating for 17 passengers, in individual seats on either side of the aisle.
With its larger fuselage, passengers could stand up whilst moving down the aisle and large windows were also provided. Baggage was stored in an aft compartment with an additional smaller area in the nose. A few peculiarities cropped up; passengers who filled the aft rows first would find that the Heron gently "sat down" on its rear skid. Pilots and ground crews soon added a tail brace to prevent the aircraft from sitting awkwardly on its tail.
Performance throughout the Heron range was relatively "leisurely", and after production at de Havilland's Chester factory ceased in 1963, several companies, most notably Riley Aircraft Corporation, offered various Heron modification "kits," mainly related to replacing the engines, which greatly enhanced takeoff and top speed capabilities. Riley Aircraft replaced the Gipsy Queens with horizontally opposed Lycoming IO-540 engines.
One U.S. airline that carried out Riley conversions was Prinair, of Puerto Rico, which replaced the Gipsy Queens with Continental IO-520 engines. Prinair also considerably stretched Heron 2 N574PR to allow extra passengers to be carried.
Connellan Airways also converted its Herons, using Riley kits. When available aircraft reached the end of their service lives, the engine conversions gave the elderly airliner a new lease on life as a number of examples were converted in the 1970s and 1980s including N415SA, a Riley Heron still flying in Sweden as of 20 May 2012 and a Riley Turbo Skyliner, tail number N600PR currently registered in the United States (this example appeared in the 1986 movie Club Paradise).
The most radical modification of the basic Heron airframe was the Saunders ST-27/-28, that basically changed the configuration as well as the "look" of the whole aircraft with two powerful turboprop engines replacing the lethargic four-engine arrangement, the easily recognisable "hump" over the cockpit disappearing, the shape of the windows changed and the wingtips being squared instead of rounded.
A Riley Turbo Skyliner variant was used in the 1986 US comedy film Club Paradise
- Heron 1: Four-engined light transport aircraft. Fitted with fixed landing gear.
- Heron 1B: This model had an increased take-off weight of 13,000 lb (5,897 kg).
- Heron 2: Four-engined light transport aircraft. Fitted with retractable landing gear.
- Heron 2A: This designation was given to a single Heron 2, which was sold to a civil customer in the USA.
- Heron 2B: This model had the same increased takeoff weight as the Heron 1B.
- Heron 2C: Redesignation of the Heron 2Bs, which could be fitted with optional fully feathering propellers.
- Heron 2D: Four-engined light transport aircraft. This model had an increased takeoff weight of 13,500 lb (6,123 kg).
- Heron 2E: VIP transport aircraft. One custom-built aircraft.
- Heron C.Mk 3: VIP transport version for the Queen's Flight, Royal Air Force (RAF). Two built.
- Heron C.Mk 4: VIP transport aircraft for Queen's Flight, RAF. One built.
- Sea Heron C.Mk 20: Transport and communications aircraft for the Royal Navy. Three ex-civil Heron 2s and two Heron 2Bs were acquired by the Royal Navy in 1961.
- Riley Turbo Skyliner: Re-engined aircraft. A number of Herons were fitted with 290 hp (216 kW) Lycoming IO-540 flat-six piston engines. The modifications were carried out by the Riley Turbostream Corporation of the USA.
- Saunders ST-27: The fuselage was lengthened by 8 ft 6 in (2.59 m), to accommodate up to 23 passengers. It was powered by two 750 shp (559-kW) Pratt & Whitney Canada PT6A-34 turboprop engines. Twelve Herons were modified by the Saunders Aircraft Corporation of Gimli, Manitoba, Canada.
- Shin Meiwa Tawron: Conversion by Shin Meiwa of Japan for Toa Airways with 260 hp (194 kW) Continental IO-470 engines replacing the originals.
- Gulf Aviation
- Ivory Coast
- New Zealand
- Puerto Rico
- São Tomé and Príncipe
- Saint Lucia
- Sierra Leone
- United Kingdom
- United States
Accidents and incidents
- On 18 April 1955, Union Aéromaritime de Transport F-BGOI, crashed into a Kupe Mountain Cameroon. 12 out of 14 passengers and crew died in the crash.
- On 7 November 1956, Braathens SAFE LN-SUR, crash landed in heavy snow on the mountain Hummelfjell in Tolga, Norway. The pilot and one passenger were killed, whilst the remaining crew and passengers survived. The Hummelfjell accident was Braathens SAFE's first fatal accident.
- On 28 September 1957, British European Airways G-AOFY, on an air ambulance flight, crashed on approach to Glenegedale Airport, Islay, in bad weather. The three occupants, two crew and one nurse, were killed.
- On 14 April 1958, Aviaco EC-ANJ, crashed into the sea off the coast of Barcelona Spain all 16 passengers and crew were killed in the crash.
- On 14 October 1960, Itavia I-AOMU crashed on Mount Capanne, Italy killing all 11 on board.
- On 17 August 1963, Fujita Airlines JA6159 crashed just after take off into Mount Hachijō-Fuji, Hachijōjima, Japan; the accident killed all 19 passengers and crew in the worst disaster suffered by the de Havilland Heron.
- On 27 January 1968, Air Comoros F-OCED flight hit the runway at Moroni, Comoros and overran the runway then crashed into the sea. 15 passengers and crew died but 1 person survived the accident.
- On 24 June 1972, Prinair Flight 191 crashed near Ponce, Puerto Rico killing five people out of 20 passengers and crew.
- On 23 October 1975, VH-CLS performing Connair Flight CK1263 crashed in a cane field at Holloways Beach after a missed approach to Cairns Airport, Queensland, Australia during a storm. The 3 crew and 8 passengers were all killed.
Specifications (Heron 2D)
Data from De Havilland Aircraft since 1909 
- Crew: two (pilot and co-pilot)
- Capacity: 14 passengers
- Length: 48 ft 6 in (14.79 m)
- Wingspan: 71 ft 6 in (21.80 m)
- Height: 15 ft 7 in (4.75 m)
- Wing area: 499 ft² (46.4 m²)
- Empty weight: 8,150 lb (3,705 kg)
- Max. takeoff weight: 13,500 lb (6,136 kg)
- Powerplant: 4 × de Havilland Gipsy Queen 30 Mk.2 6-cylinder inverted inline air-cooled piston engine, 250 hp (186 kW) each
- Cruise speed: 159 kn (183 mph, 295 km/h)
- Range: 795 nmi (915 mi, 1,473 km)
- Service ceiling: 18,500 ft (5,600 m)
- Rate of climb: 1,140 ft/min (5.8 m/s)
- Related development
- Aircraft of comparable role, configuration and era
|Wikimedia Commons has media related to De Havilland Heron.|
- Jackson, A.J. British Civil Aircraft Since 1919, Volume 2. London: Putnam & Company, 1973. ISBN 0-370-10010-7.
- "FAA Supplemental Type Certificate SA1685WE." faa.gov. Retrieved: 13 August 2008.
- Ebert, Roger. " 'Club Paradise' Review". Roger Ebert.com. Retrieved: 1 April 2007. Note: The Riley Heron is integral to the plot as it unloads planeloads of unsuspecting tourists at a ramshackle resort.
- "FAA Supplemental Type Certificate SA1368WE." faa.gov. Retrieved: 13 August 2008.
- Taylor 1965, p. 107.
- "Congo, Part 1; 1960-1963". ACIG. 2003. Retrieved 2013-08-09.
- Accident history for HAC at Aviation Safety Network
- Jackson 1987, p. 494.
- Bain, Gordon. De Havilland: A Pictorial Tribute. London: AirLife, 1992. ISBN 1-85648-243-X.
- Green, William. Macdonald Aircraft Handbook. London: Macdonald & Co. (Publishers) Ltd., 1964.
- Jackson, A.J. De Havilland Aircraft since 1909. London: Putnam, Third edition, 1987.
- Taylor, John W. R. (editor). Jane's All The World's Aircraft 1965-66. London: Sampson Low, Marston, 1965.