De Havilland Heron

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The correct title of this article is de Havilland Heron. The initial letter is shown capitalized due to technical restrictions.

DH.114 Heron

de Havilland DH-114 Heron, recently restored to flying condition by a private individual; photograph taken at the EAA Rocky Mountain Regional Fly-in c. 2005
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

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 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.

1 Design and development
2 Operational service
3 Variants
4 Operators
- 4.1 Civil operators
- 4.2 Military operators
5 Specifications (Heron 2D)
- 5.1 General characteristics
- 5.2 Performance
6 References
7 External links
8 Related content

[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. 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 deficencies, 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 peculiarites 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. As the aircraft reached the end of its service life, a number of conversions and modifications were made available including switching to four horizontally-opposed engines Lycoming engines, which greatly enhanced takeoff and top speed capabilities.

After production ceased in 1963, several companies offered various conversions, with the most extreme being the Saunders ST27/28, that basically changed the look of the whole aircraft; it was reduced to two turboprop engines, the easily recognisable "hump" over the cockpit disappeared, the shape of the windows were changed, and the wingtips were squared instead of rounded.

Trivia: a Heron, tail number N600PR, appears in the 1986 Robin Williams/Harold Ramsey movie Club_Paradise, approximately 20 minutes in. However, it appears to have been converted from the four "Gipsy Queen" in-line six-cylinder engines to four horizontally-opposed engines; possibly the Lycoming (TI?)O-540 six-cylinder.

[edit] Variants

Heron 1 :
- Heron 1B :
Heron 2 :
- Heron 2A :
- Heron 2B :
- Heron 2C :
- Heron 2D :
- Heron 2E : VIP transport aircraft. One built.
Heron 3 : VIP transport version for the Queen's Flight, RAF. Two built.
Heron 4 : VIP transport aircraft for Queen's Flight, RAF. One built.
Sea Heron C.Mk 20 : Transport and communications aircraft for the Royal Navy.
Riley Turbo Skyliner :
Saunders ST-27 :
Saunders ST-28 :

[edit] Operators

[edit] Civil operators

Australia

Butler Air Transport
Connellan Airways

Belgium

SABENA

Indonesia

Garuda Indonesia

Japan

All Nippon Airways
Toa Domestic Airline

New Zealand

National Airways Corporation

Norway

Braathens SAFE: 8 aircraft from 1952 to 1960

Puerto Rico

Prinair

United Kingdom

British Airways
British European Airways
Cambrian Airways
Jersey Airways
West African Airways Corporation (joint venture between Nigeria, Gambia, Sierra Leone, and Ghana)