Heinkel HD 27

Heinkel HD 27
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Type:	Mail plane
Design country:	German Empire
Manufacturer:	Heinkel
First flight:	March 1925
Commissioning:	1925
Number of pieces:	1

The Heinkel HD 27 was a German mail plane developed in the 1920s by Ernst Heinkel Flugzeugwerke in Warnemünde .

history

The contract for the construction was given to Ernst Heinkel on February 14, 1925 by Cox-Klemin . The American company had already ordered two Heinkel types with two HD 17s in 1923 and was now looking for an airplane to transport mail with a payload of 570 kg in a very short time . Since mail flights were carried out almost exclusively at night during this time, the model should also be able to be used in this way. Due to the urgency, the Warnemünde-based company was given a development and construction time of just six weeks. Heinkel, known for the quickest possible implementation of customer requests, began immediately with the creation of the drafts and two weeks after the order was placed with the construction phase of the sample known as HD 27. Four weeks later, the aircraft with the serial number 226 was completed as requested and could be flown in by the works pilot Hans Leutert. The HD 27 was designed to be easy to repair and quickly dismantled for transport. Following the trial phase, it was brought to Hamburg at the end of the month and shipped from there to the United States. There she was successfully used as Cox-Klemin "Night Hawk" for three years in the service of the US Air Mail Service , until in 1928 she and the hangar in which she was parked fell victim to a tornado . Heinkel further developed the HD 27 into the HD 39 in 1926 .

construction

The HD 27 was a tensioned, single-handle double - decker in conventional wooden construction . Her hull consisted of four with transverse frames connected longitudinal bars with a square cross-section and semicircular curved fuselage. The engine mount was clad with sheet metal up to the level of the upper wing leading edge, behind which a fire bulkhead was attached. The HD 27 was equipped with two cargo holds; the larger of these was 1.7 m³ and was located between the firewall and the front crew cabin. It could be loaded through two flaps on the upper and on the port side and was provided with a folding emergency seat at the rear. The two open crew cabins followed in tandem , followed by the second cargo hold with a side loading flap in the left fuselage curve. It was also possible to convert the front luggage compartment into a third, open cabin by removing the upper flap and installing another seat, so that the HD 27 was able to carry two other people in addition to the two crew members.

The wings were made of wood with two spars ; mostly covered with fabric and only covered with plywood on the lower sides between the stiles . The upper and lower wings were connected to each other with N-struts and crossed out with tensioning wires, the canopy of the upper middle section was also connected to the fuselage by N-struts. The tail structure was covered with fabric and was mostly made of wood, only the elevator , which was adjustable in flight , was made of tubular steel . All oars were balanced.

The HD 27 had a rigid main landing gear, profile steel tube with a two-part axle and disk wheels . At the stern there was a steerable grinding spur.

Technical specifications

Parameter	Data
crew	1-2
Passengers	2
span	13.6 m (top) 13.0 m (bottom)
length	9.2 m
height	3.92 m
Wing area	51.6 m²
Preparation mass	1275 kg
Payload	1055 kg
payload	570 kg
Takeoff mass	2330 kg
drive	a water-cooled twelve-cylinder - four stroke - V engine
Type	Liberty L-12A
Starting power nominal power continuous power	423 hp (311 kW) at 1800 rpm 400 hp (294 kW) at 1700 rpm 380 hp (279 kW) at 1600 rpm
Top speed	205 km / h near the ground
Cruising speed	190 km / h near the ground
Landing speed	81 km / h
Rate of climb	5.4 m / s
Rise time	4.0 min at 1000 m altitude 9.6 min at 2000 m altitude
Service ceiling	6500 m
Range	980 km (optimal)
Flight duration	5.0 h

literature

Volker Koos: Ernst Heinkel Flugzeugwerke 1922–1932. Heel, Königswinter 2006, ISBN 3-89880-502-6 , pp. 70/71.
Volker Koos: Aviation between the Baltic Sea and Breitling. Warnemünde sea and land airfield 1914–1945. Transpress, Berlin 1990, ISBN 3-344-00480-8 , pp. 60/11 and 66.