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Subject: de Havilland Heron
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https://en.wikipedia.org/wiki/De_Havilland_Heron
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, also exported to about
30 countries. Herons later formed the basis for various conversions, such as the
Riley Turbo Skyliner and the Saunders ST-27 and ST-28.
Immediately after the Second World War, the aircraft manufacturer de Havilland
developed the DH.104 Dove, a small twin-engined passenger aircraft intended as a
replacement for the earlier Dragon Rapide, 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.
Role
Airliner
Manufacturer
de Havilland
First flight
10 May 1950
Introduction
1950
Status
Retired
Primary users
Garuda Indonesian Airways
See Operators
Number built
150
Developed from
de Havilland Dove
Variants
Saunders ST-27
The first Heron, Series 1A suffered deficiencies, as NAC soon discovered. First,
the aircraft was generally underpowered. Its quite heavy engines (weighing about
880 pounds (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 unpaved 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.
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.
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.
Specifications (Heron 2D)
General characteristics
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)
Empty weight: 8,150 lb (3,705 kg)
Max. takeoff weight: 13,500 lb (6,136 kg)
air-cooled piston engine, 250 hp (186 kW) each
Performance
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)
*
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