Hawker Hart

Key Facts

Main Role:

Two-Seat Light Day Bomber

Configuration:

Tractor biplane

Country:

United Kingdom

Current Status:

Out of Service, Out of Production




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Development

The Hawker Hart was possibly the most adaptable aircraft designed during the period between the two great wars. Designer Sydney Camm hit on a formula which originated as a two-seat day bomber that was easily adapted to the single-seat fighter role as well as being used as a seaplane, reconnaissance aircraft and indeed a dive bomber. The variants were given names such as Audax, Demon, Hardy, Hind, Osprey, Hartbees, Fury and Hector. At first glance all were look-alikes except for the Hector which had a Napier Dagger “H” type engine.

The Air Ministry specification 12/26 encouraged Camm to look into the advantages of the low drag water cooled in-line engine so as to gain an increase in speed over the other existing types. The engine chosen was the Rolls-Royce Falcon XI. The airframe of the Hart was to have the smallest frontal area possible but at the same time having 2 crew members, defensive armament and bombs.

A new approach for construction of the airframe was drawn up which constituted a steel tube primary fuselage structure. Also the wings having spars made with rolled steel tubes top and bottom linked with a light gauge metal web. The top wing having a mild sweep back. The aircraft was built to take either a cross axle undercarriage or twin floats. The float version having the larger fin and rudder of the Hawker Osprey so as to offset the added frontal area created by the floats.

The original mock-up was started in 1927 and the prototype (J9052) was first flown powered by the Rolls-Royce Falcon F.XIA and taken into the air by Gp. Capt. Bulman in June 1928. The first public appearance being at the Olympia Aero Show during July 1929.

Service evaluation of the Hart began at the end of 1928 at Martlesham Heath with as many as eight trials between that date and May 1929. The trials were held in competition with the Avro Antelope and the Fairey Fox Mk.2. The result being that the Hart outclassed its competitors with speed, handling & maintenance. The trials culminating with specification 9/29 for a production batch of 15 examples as pre-production aircraft. Twelve of this batch being issued to No.33 Bomber Squadron which was previously equipped with Hawker Horsleys. One example was sent to Risalpur, India, for tropical trials. This aircraft had a rather sad life. First it collided with a Vulture and then was burned out in a hangar fire, some reports indicating rebels as the culprits.

The entire British production of the Hart totalled 984, nearly half of which were trainers. The production being shared by Hawker, Vickers, Gloster and Armstrong Whitworth. In 1936 three out of every four new squadrons were equipped with Hart variants. Eight Harts were exported to Estonia and four Pegasus powered Harts were sent to Sweden, while another twenty-four were built by the Swedish State Aircraft Factory. A developed version know as the Hartbees was produced for the South African Air Force – four being supplied by Hawker and sixty-five built in Pretoria.

Various Harts were used as engine test beds, particularly G-ABTN which undertook trials with the Bristol Jupiter and Pegasus. Others were tested with the Armstrong Siddeley Panther, Bristol Mercury, Rolls Royce P.V.12, Rolls Royce Merlin F, Lorraine Petrel, Hispano-Suiza 12.X and the Napier Dagger, which became the Hawker Hector. The most interesting Hart was G-ABMR. This visited 15 European countries between 1930 and 1936. It wore wheel spats, an Audax hook, Osprey tail, low pressure tyres and a Hind tailwheel on different occasions. It was used for carrying press photographers to and from Brooklands and in full camouflage became used as a ferry pilot taxi during the war. After which it raced in Hawker colours (blue with silver and white trim) and gave appearances at various garden parties. Later it suffered damaged in a forced landing and was lovingly restored, ending up as a static display at the RAF Museum, Hendon. A Hart Trainer (K4972) is also preserved at Hendon.

Variants

Requirement Specification: 12/26 (development), 9/29 (production), 9/31 (Hart India), 8/32 (Hart Trainer)
Manufacturers Designation: –

Development History:
Hart project	The initial design for the Hart featured a split-axle undercarriage with pneumatic shock-absorbers and a gravity fuel system. I-shape wing struts.
Hart prototype	First prototype with F.XIB (Kestrel I) engine. Cross-axle undercarriage with Vickers oleo-pneumatic struts, pump-fed fuel system. N-shape wing struts.
Hart I	Standard production bomber version, with Kestrel IB engine of 525 hp.
Hart II	Alternative designation for Hart Trainer.
Hart Trainer (Interim)	Dual controls trainer conversion of bomber airframe. Kestrel IB engine. Armament removed, original wing retained.
Hart Trainer (Series 2/2A)	Production dual controls trainer version. Full second cockpit with windscreen. 2.5 degree wing sweep instead of 5 degrees to maintain cg position after removal of heavy gun-ring. Kestrel IB engine. Armament removed. Later aircraft with derated Kestrel X engine and tailwheel instead of skid. Retrofit with long exhaust pipes common.
Hart private venture	Four privately funded aircraft built for development and sales demonstrations. Various engines fitted, including Bristol Jupiter and Pegasus, RR Kestrel V, AS Panther.
Hart Two-Seat Fighter	Dedicated 2-seat fighter version for 23 Sqn RAF. Supercharged Kestrel IIS engine. Later developed into Hawker Demon.
Hart (Communications)	Version for 24 Sqn RAF for communications duties. No bomb gear or gun armament.
Hart (India)	Tropical bomber version with new breather vents in engine cowling, Kestrel IB engine, additional water stowage and supply container racks.
Hart S.E.D.B.	Single Engine Day Bomber – official designation for Mk I bomber. Kestrel IB engine.
Hart (Special)	Bomber version for Middle East use with lighter derated Kestrel X engine (515 hp), larger radiator and low pressure tyres with main wheel brakes.
Estonian Hart	Export version with 525 hp Kestrel IIS engine and interchangeable wheel and float undercarriage.
Swedish Hart	Export version for Sweden. 580 hp Bristol Pegasus IM2 radial engine. Hawker-built.
Naval Hart	Hart first prototype converted in 1929 for evaluation by Fleet Air Arm. Developed into the Hawker Osprey.
B 4	Redesignation of S 7A aircraft. 580 hp Bristol Pegasus IM2 engine.
B 4A	Swedish-built Hart with 580 hp Nohab Mercury VIIA engine.
B 4B	Version of B 4A with 755 hp Bristol Perseus XI engine.
S 7A	Initial Swedish designation for UK-built Swedish Hart aircraft – later B 4.

Estonian Hart 151 – note the long exhaust pipes. (photo, via author)	Estonian Hart 152. (photo, via author)

History

Key Dates:
May 1926		Specification 12/26 issued by Air Ministry
December 1926		Tender for bomber design submitted by Hawker
April 1927		Mock-up of Hart design completed
July 1927		Contract for one prototype placed with Hawker
? June 1928		Maiden flight of Hart first prototype (J9052)
December 1928		RAF evaluation begins
May 1929		First production order for 15 aircraft
July 1929		First public appearance at Olympia Aero Show
25 February 1930		First production delivery to 33 Sqn RAF
7 September 1931		Hart (India) first flight
early 1932		First export order placed by Estonia
20 April 1932		Hart Trainer prototype (K1996) first flight
March 1933		Hart enters service with Auxiliary Air Force
6 January 1934		Swedish Hart first flight
late 1935		RAF begins to replace Hart bomber in regular squadrons
1936		Hart bomber finally withdrawn from regular RAF squadrons
October 1936		Last UK-production Hart delivered
1938		Hart withdrawn from UK front-line service with Aux AF squadrons
July 1939		Last RAF Harts withdrawn from frontline service in India
1939		Hart Trainer replaced in the RAF training role by Harvard and Master
11 January 1940		Swedish Harts join Finland’s Winter War with Russia
1943		SAAF retires Hart from comms duties
1947		Last Swedish Harts retired from service
1972		‘J9941’ (G-ABMR) presented to the RAF Museum, Hendon

Operators

Military Operators

Canada – Air Force	(1 new build aircraft for trials)
Egypt – Air Force	(14 ex-RAF aircraft)
Estonia – Air Force	(8 new build aircraft)
Germany – Luftwaffe	(1+ captured)
South Africa – SAAF	(320+ Hart/Hart Special)
Southern Rhodesia – Air Force	(3 ex-RAF aircraft)
Sweden – Air Force	(46 new-build aircraft)
UK – Fleet Air Arm	(5 ex-RAF aircraft)
UK – Royal Air Force	(7 UK Sqns + 5 India/Middle East; 23 Flying Training Schools)
Yugoslavia – Air Force	(4 RAF aircraft on short-term loan)

Government Agencies

UK – A&AEE Boscombe Down

(Several used for test duties)

Civilian Operators

None

Specifications

Hawker Hart I/Hart S.E.D.B.
Role: Two-seat light day bomber
Crew: Two
Dimensions: Length 29 ft 4 in (8.94 m); Height 10 ft 5 in (3.17 m) tail down over propeller arc; Wing Span 37 ft 3 in (11.35 m); Wing Area 348.0 sq ft (32.33 sq m)
Engine(s): One liquid-cooled, 12-cylinder Vee, Rolls-Royce Kestel IB of 525 hp (392 kW) – or Kestrel XDR of 510 hp (381 kW).
Weights: Empty Equipped 2,530 lb (1148 kg); Loaded 4,554 lb (2066 kg)
Performance: Maximum level speed 184 mph (296 kph) at 5,000 ft (1524 m); Time to 10,000 ft (3,048 m) 8 min 20 sec; Service ceiling 21,350 ft (6,506 m); Range 470 miles (756 km); Endurance 2 hr 45 min.
Armament: One forward firing .303 in (7.7 mm) Vickers Mk.II or Mk.III machine-gun in port forward fuselage side; one 0.303 Lewis gun on ring mounting in rear cockpit with seven 97-round magazines; up to 520 lb (236 kg) of bombs under lower wings.

Hawker Hart (Trainer)
Role: Tandem two-seat advanced trainer
Crew: Two
Dimensions: Length 29 ft 4 in (8.94 m); Height 10 ft 5 in (3.17 m) tail down over propeller arc; Wing Span 37 ft 4 in (11.38 m); Wing Area 349.5 sq ft (32.47 sq m)
Engine(s): One liquid-cooled, 12-cylinder Vee, Rolls-Royce Kestel IB of 525 hp (392 kW) – or Kestrel VDR or XDR of 510 hp (381 kW).
Weights: Empty Equipped 3,020 lb (1370 kg); Loaded 4,150 lb (1882 kg)
Performance: Maximum level speed 168 mph (270 kph) at 3,000 ft (914 m); Time to 10,000 ft (3,048 m) 6 min 30 sec; Service ceiling 22,800 ft (6,950 m); Range 430 mls (692 km); Endurance 2 hr 30 min.
Armament: None.

Production

Design Centre

Head of Design Team: Sydney Camm
Design Office: H. G. Hawker Engineering Co. Ltd, Kingston-upon-Thames, Surrey. (Hawker Aircraft Ltd 1933+).

Manufacture

H. G. Hawker Engineering Co. Ltd (Kingston-upon-Thames, Surrey, UK.)
Version	Quantity	Assembly Location	Time Period
Hart proto.	1	Canbury Park Road	Oct 1927-May 1928
Hart Mk I	15	Kingston	June 1929-Feb 1930
Hart Experimental	4	Kingston	1930-1931
Hart Mk I	32	Kingston	Nov 1930-Jan 1931
Hart Trainer proto.	1 conv Audax	Kingston	early 1932
Hart 2-seat Fighter	6	Kingston	1930-1931
Hart India	50	Kingston	Sept 1931-April 1932
Hart India	2	Kingston	early 1934
Hart India	5	Kingston	early 1937
Hart Bomber	46	Kingston	Feb 1932-May 1932
Hart Communications	4	Kingston	Feb 1932-May 1932
Hart Trainer (Interim)	2	Kingston	early 1932
Hart Trainer	13	Kingston	Apr 1933-June 1933
Hart Trainer	21	Kingston	Feb 1934
Hart Trainer Srs 2	20	Kingston	Mar-Apr 1935
Estonian Hart	8	Kingston	1932
Swedish Hart (B 4)	4	Kingston	early 1934
Total:	234

Armstrong Whitworth Aircraft Co Ltd (Coventry, West Midlands, UK.)
Version	Quantity	Assembly Location	Time Period
Hart S.E.D.B	24	Coventry	July 1933-Nov 1933
Hart S.E.D.B	46	Coventry	Mar 1934-July 1934
Hart Communications	4*	Coventry	Mar 1934-July 1934
Hart S.E.D.B	18	Coventry	June-July 1934
Hart Communications	2	Coventry	July 1934
Hart S.E.D.B	59	Coventry	Jan-May 1935
Hart Trainer Srs 2A	167	Coventry	July 1935-Feb 1936
Hart Trainer Srs 2A	136**	Coventry	Mar-Oct 1936
Total:	456

* not 2 as given in some sources.
** not 146 as given in some sources.

Gloster Aircraft Co Ltd (Hucclecote, Gloucestershire, UK.)
Version	Quantity	Assembly Location	Time Period
Hart Special	16 conv Audax	Hucclecote	July-Aug 1935
Hart Special	30	Hucclecote	Nov 1935-Feb 1936
Total:	46

Vickers Aircraft Co Ltd (Weybridge, Surrey, UK.)
Version	Quantity	Assembly Location	Time Period
Hart S.E.D.B	65	Weybridge	18 Feb 1932-April 1933
Hart S.E.D.B	45	Weybridge	Feb 1934-April 1934
Hart Communications	2	Weybridge	Feb 1934-April 1934
Hart Trainer Srs 2A	114	Weybridge	May 1935-28 May 1936
Total:	226

ASJA (Trollhattan, Sweden.)
Version	Quantity	Assembly Location	Time Period
Swedish Hart (B 4A)	18	Trollhattan	1935-1936
Total:	18

Götaverken (Gothenburg, Sweden.)
Version	Quantity	Assembly Location	Time Period
Swedish Hart (B 4A)	3	Gothenburg	1935-1936
Total:	3

Central Workshops of the Air Force (CVM) (Malmo, Sweden.)
Version	Quantity	Assembly Location	Time Period
Swedish Hart (B 4A)	19	Malmo	1935-1936
Swedish Hart (B 4B)	2	Malmo	1935-1936
Total:	21

Total Produced: 962 a/c in UK + 42 a/c in Sweden = 1004 a/c, (incl. 474 trainers and 460 bombers).

Production List

To be added.

More Information

Books

‘Hawker Aircraft Since 1920’ [Order this book from Amazon UK]
by Francis K Mason
Published by Putnam Aeronautical Books, 1991 ISBN: 0 85177 839 9
* Detailed company history with a chapter on the Hart.

‘British Flight Testing: Martlesham Heath 1920-1939’ [Order this book from Amazon UK]
by Tim Mason
Published by Putnam Aeronautical Books, 1993 ISBN: 0 85177 857 7
* Includes a summary of the aircraft flight testing conducted on the Hart.

‘The British Bomber Since 1914’ [Order this book from Amazon UK]
by Francis K. Mason
Published by Putnam Aeronautical Books, 1994 ISBN: 0 85177 861 5
* Includes a section on the Hart.

‘No.5 – Hawker Hart & derivatives (Aeroguide Classics)’
by Ray Rimell
Published by Linewrights Ltd, May 1989 ISBN: 0-946958-34-3
* Excellent pictorial reference to the Hart.

‘The Hawker Hart: Profile No.57’
by Francis K. Mason
Published by Profile Publications Ltd, 1965 ISBN: n/a
* Concise well illustrated history of the Hart.

Magazines

Planes Spring 1983
Air Enthusiast No.96 Nov/Dec 2001 & No.97 Jan/Feb 2002
Aeroplane Monthly November 1980
Scale Aircraft Modelling February 1993

Links

wikipedia: Hawker Hart
(concise profile)

Hawker Hart
(British Aircraft of World War II: summary history)

Hawker Hart in Detail
(Close-up photos of Swedish Hart)

Hawker Hart
(British Aircraft Directory: summary of key info)

Hawker Hart
(RCAF use of Hart)

Shop

Flight Simulator Models:
To be added.

Scale Models:
To be added.

Scale Drawings:
Scale Aviation Modeller July 2004
Aviation NewsVol.8 No.5

Videos:

Hawker Hart
(1930s movie of Hart in RAF service)