In 1923, Hawker developed and patented a new system of primary structure assembly for aircraft which involved the use of predominantly metal in their construction. Lengths of steel and duralumin tubing were swaged to rectangular box section at their ends and then bolted together using fishplates and bolts to form a simple but strong framework, cross-braced with tensioning wires. The advantage was that the process was thought to be cheaper than previous wood construction methods and that the structure was more easily repaired compared to using welded joints.
As an experiment into this new construction system, Hawker designer Sydney Camm was put in charge of the development of a 'redesigned' version of the company’s succesfull Woodcock single-seat fighter, which had first flown in March 1923.
Although the resulting aircraft, named the Heron, looked broadly similar to the Woodcock (and indeed it originally started life as the third marque of the Woodcock) the differences in weight distribution and other elements led to quite a different machine in terms of design detail.
The wings, with no sweepback, incorporated twin spars of light-gauge steel tube to which wooden ribs were attached. These differed from those of the Woodcock in being of unequal span and increased stagger, with pronounced dihedral on the lower wings.
A more elegant fin and horn-balanced rudder arrangement replaced the Woodcock’s rather old-fashioned tail configuration and a 455 hp Bristol Jupiter VI nine-cylinder radial engine replaced the Woodcock I’s 360 hp Armstrong Siddeley Jaguar.
On completion of the prototype (J6989) Hawker Test Pilot F.P (Fred) Raynham took the aircraft aloft for its first flight in early 1925 and it made its public debut at the RAF Display at Hendon that June.
In December 1925, the sole Heron was sent to the Aeroplane & Armament Experimental Establishment (A&AEE) at Martlesham Heath where No.15 Sqn (the specialist armament unit at the A&AEE) used it for Gun Trials until the spring of 1927. Thereafter, it went to No 22 Sqn for handling and performance trials where it garnered positive reports from pilots for its 'good flying characteristics' and from groundcrew for its 'ease of servicing'.
Despite earning such praise throughout its trials programme and with Air Ministry Specification 25/24 having been issued to accommodate its construction and flight programme, no orders were forthcoming and it was struck off charge in May 1928.
Stripped of its armament, the Heron was purchased back from the Air Ministry by Hawker and given a civil registration (G-EBYC) as it was intended for it to be flown in the King’s Cup Air Race of 1928. Unfortunately, as Hawker pilot P.W.S. Bulman was taxying out to participate in the race on 27th July he ran into a Morris Oxford bullnose car, damaging both in the process.
The aircraft was eventually repaired but by then its Certificate of Airworthiness had lapsed and so it was retired from the civil register in January 1930.
Like several other Hawker types of the period, little appears to be known of its ultimate fate although it was reportedly kept in the Hawker Flight Shed at Brooklands until the outbreak of the Second World War but no one appears to know what happened to it after that.
Variants & Numbers
|Powerplant||One 455 hp Bristol Jupiter VI nine-cylinder air-cooled radial engine driving a Watts two-bladed wooden propeller; later fitted with Fairey-Reed metal propeller|
|Capacity and Armament||Single pilot; two fixed forward-firing Vickers machine-guns with Constantinesco “CC” synchronisation gear, 600 rounds per gun|
|Maximum speed||156 mph at 9,800ft|