de Havilland Heron

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DH.114 Heron
de Havilland DH-114 Heron
Type Airliner
Manufacturer de Havilland
Maiden flight 10 May 1950
Introduced 1950
Primary users British European Airways
See Operators
Number built 150
Developed from DH.104 Dove
Variants Saunders ST-27
Image:Heron Panel.jpg
DeHavilland Heron Instrument Panel

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 de Havilland Dove, with a stretched fuselage and two more engines, for a total of four. It was designed as a rugged, conventional low-wing monoplane with tricycle undercarriage that could be utilized on regional and commuter routes. One hundred and fifty 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.

Contents

[edit] 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; lengthened the fuselage in order to provide room for more passengers or freight, and increased the wingspan to make room for two additional engines. The Heron was of all-metal construction, and was laid out as a conventional design; the resulting aircraft was able to use many of the parts originally designed for the Dove, thus simplifying logistics for airlines employing both types.

The emphasis was on rugged simplicity in order 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 [1]. 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 Air Show, still glistening in its polished metal state. By November, the prototype had received its formal British Certificate of Airworthiness and had embarked to Khartoum and Nairobi for tropical trials.

The prototype was then painted and "prepped" as a company demonstrator, undergoing a trial in 1951 with British European Airways on their Scottish routes. Following the successful completion of the prototype trials as a regional airliner, the Heron began series production. The first deliveries were to NAC, (later part of Air New Zealand).

[edit] Operational service

The first Heron, Model 1A suffered from a number of deficiencies, as NAC soon discovered. First of all, the aircraft was generally underpowered. It was powered by four quite heavy engines (weighing approximately 400 kg each), providing as little as 250 hp. By comparison, later modifications or rebuilt aircraft (such as the Saunders ST27) had more power in one engine than the Heron had in total! Unlike the Dove, the Heron came with a fixed undercarriage and no nosewheel steering, which simplified maintenance, but reduced top speed.

After 51 aircraft had been built of models 1A-D, production switched to the Model 2, featuring retractable landing gear, which reduced drag and fuel consumption, and increased the top speed marginally. The Model 2A was the equivalent of the 1A, the basic passenger aircraft while the Model 1B/2B had higher maximum takeoff weight, the Model 2C featured fully-feathering propellers, the Heron Model 2D had an even higher maximum takeoff weight, while the Heron Model 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 DH114 was able to provide reliable and comfortable service. With its larger fuselage, customers could stand up and seating for 17 passengers, with a single row of seats on either side of the aisle, featured large windows. Baggage was stored in an aft compartment with an additional smaller area in the nose. A few peculiarities cropped up; customers who filled the aft rows first would find that the Heron gently "sat down" on its rear skid. Pilots and flight crews soon added a tail brace to prevent the aircraft from sitting awkwardly on its tail.

Performance throughout the Heron range was "leisurely" resulting in many operators contemplating engine conversions including switching to four horizontally-opposed Lycoming engines, which greatly enhanced takeoff and top speed capabilities. After production ceased in 1963, several companies, most notably Riley Aircraft Corporation, offered various Heron modification "kits," mainly related to engine swaps. 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 as of 2005 and a Riley Turbo Skyliner, tail number N600PR currently registered in the United States (this example appeared in the 1986 movie Club Paradise[2]).

The most radical modification of the basic Heron airframe was the Saunders ST27/28, 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.

[edit] Variants

Image:Tawron03.JPG
DH114 Tawron（Japanese）
  • 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-lbs (5897-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-lbs (6123-kg).
    • Heron 2E: VIP transport aircraft. One custom built aircraft.
  • Heron C.Mk 3: VIP transport version for the Queen's Flight, 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 2.59m (8ft 6in), to accommodate up to 23 passengers. It was powered by two 750-shp (559-kW) Pratt & Whitney Canada PT6A-34 turboprop engines. 12 Herons were modified by the Saunders Aircraft Corporation of Gimli, Manitoba, Canada.
    • ST-27A and ST-27B : The original designations of the ST-28.
    • Saunders ST-28: Improved version of the ST-27. One prototype built.
  • Tawron: Toa Domestic Airline(Japan); Continental IO-470s replaced the original engines.

[edit] Operators

See also: List of De Havilland Heron operators

[edit] Military operators

[edit] Civil operators

[edit] Specifications (Heron 2D)

General characteristics

  • Crew: two (pilot and co-pilot)
  • Capacity: 14 passengers
  • Length: 48 ft 6 in (14.78 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 (3,700 kg)
  • Max takeoff weight: 13,500 lb (6,100 kg)
  • Powerplant: 4× de Havilland Gipsy Queen 30 Mk.2 6-cylinder inverted inline piston engine, 250 hp (186 kW) each

Performance

[edit] References

Notes
  1. ^ Jackson, A.J. British Civil Aircraft Since 1919, Volume 2. London: Putnam & Company, 1973. ISBN 0-370-10010-7.
  2. ^ Ebert, Roger. Club Paradise Review. Roger Ebert.com. [1] Access date: 1 April 2007. Note: The Riley Heron is integral to the plot as it unloads planeloads of unsuspecting tourists at a ramshackle resort.
Bibliography
  • Bain, Gordon. De Havilland: A Pictorial Tribute. London: AirLife, 1992. ISBN 1-85648-243-X.

[edit] External links

[edit] Related content

Related development

de Havilland Dove

Designation sequence

DH.110 - DH.112 - DH.113 - DH.114 - DH.115 - DH.121 - DH.125

v • d • e
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