The 1921 Avro 552 was a variant of the Avro 504N with a Wolseley Viper engine.

Engine: 1 x 180hp Wolseley Viper
Wingspan: 10.97 m / 36 ft 0 in
Length: 8.53 m / 28 ft 0 in
Height: 3.18 m / 10 ft 5 in
Wing area: 30.66 sq.m / 330.02 sq ft

1919

Avro 548
Engine: 1 x 80hp Renault
Take-off weight: 882 kg / 1944 lb
Empty weight: 607 kg / 1338 lb
Wingspan: 10.97 m / 36 ft 0 in
Length: 8.97 m / 29 ft 5 in
Height: 3.18 m / 10 ft 5 in
Wing area: 30.66 sq.m / 330.02 sq ft
Max. speed: 129 km/h / 80 mph
Cruise speed: 105 km/h / 65 mph
Range: 282 km / 175 miles

With the UK staging the first post-war Schneider Trophy contest in 1919, Avro decided to build and enter an aircraft, the Avro 539. In order to achieve the highest possible speed, it was the smallest practical single-engined aircraft that could be designed around the selected powerplant, a Siddeley Puma inline engine. An unequal-span biplane, with ailerons on both wings, it was of conventional construction with two single-step floats that were long enough to eliminate the need for a third float beneath the tail. First flown on 29 August 1919, only 12 days before the day of the race, the Avro 539 had performance that was considered to be generally satisfactory. However, when taking off from Cowes to take part in the seaworthiness trials, which were a compulsory preliminary to the speed contest, a float was seriously damaged by floating debris. Avro was given five days to repair, and used this time also to modify the tail unit. When the floatplane appeared again it carried the registration G-EALG, and because of the modifications was re-designated Avro 539A. When tested, its performance was not good enough to warrant selection for the speed contest, with the result it was delegated as the British reserve aircraft. The contest, held at Bournemouth on 10 September 1919 was a fiasco in foggy conditions and was abandoned.

The 539 was converted to a landplane and took part in the Aerial Derby of 1920, but force-landed with a fuel system leak. Then extensively modified, and with a 450 hp / 336 kW Napier Lion engine installed, it was re-designated Avro 539B. During tests before the 1921 Derby, the aircraft overshot on landing and was completely wrecked.

Avro 539
Engine: 1 x 240hp Siddeley Puma
Wingspan: Upper 25 ft 6 in / 7.77 m / lower 24 ft 6 in / 7.47 m
Length: 6.50 m / 21 ft 4 in
Height: 2.97 m / 9 ft 9 in
Wing area: 18.12 sq.m / 195.04 sq ft
Take-off weight: 962 kg / 2121 lb
Empty weight: 758 kg / 1671 lb

Early post-war pleasure flying was booming and a batch of Avro 504Ks were modified at the company’s Hamble factory. The fuselage was widened 9 in / 22.8 cm to accommodate four passengers in two pairs in the rear cockpit. The first conversion flew at Hamble in April 1919 and was later fitted with floats, the only such floatplane.

In all, 25 Avro 536s were built. 10 at Hamble, 12 at Manchester, and three at Croydon, where Surrey Flying Services undertook assembly.

A considerable amount of joy-riding was undertaken with these open-cockpit aircraft, and one was completed as a two-seater with a long range fuel tank. The last 536s were withdrawn from use at the end of 1930, these being the Surrey Flying Services machines, which had been fitted with 130 hp / 99 kW Clerget engines when Bentley rotaries became unavailable.

The Last Hamble-built Avro 536 was finished as the Avro 546 four-seat cabin biplane. The pilot was seated outside, I a cockpit above the three-seat cabin. Registered in December 1919, the 546 flew very little and its registration was cancelled 12 months later.

Avro 536
Engine: 1 x 130hp Clerget or 150hp Bentley B.R.1
Wingspan: 11.20 m / 37 ft 9 in
Length: 8.97 m / 29 ft 5 in
Height: 3.18 m / 10 ft 5 in
Wing area: 31.12 sq.m / 334.97 sq ft
Take-off weight: 1011 kg / 2229 lb
Empty weight: 650 kg / 1433 lb
Max. speed: 145 km/h / 90 mph
Cruise speed: 113 km/h / 70 mph
Ceiling: 3658 m / 12000 ft
Range: 306 km / 190 miles
Seats: 5

After WW1, A.V.Roe entered the light aircraft field with the Avro 534 Baby, a low-powered lightweight single-seat biplane. At the time, the only suitable engine was a 35 hp / 26 kW Green, which was modified by the makers. Designed around this machine, the Baby first flew on 39 April 1919, Just two minutes after take off it crashed at Hamble, the pilot having inadvertently switched off the ignition.

A second Baby flew on 10 May 1919, powered by the original engine, salvaged from the first aircraft, and this machine proved to have reasonable performance.

Records indicate that about nine Babies were built at Hamble, several achieving fame in notable flights.

Bert Hinkler was awarded the Britannia Trophy for 1 650 mile / 1046 km Croydon to Turin flight in 9 hr 30 min, while the third Baby won the 1920 Aerial Derby. One was sold to Russia, but the longest surviving example was probably the first production aircraft, which went to Australia and remained on that country’s civil register until 1936.

Variants

Avro 534A Water Baby
Twin-float seaplane flown in October 1919. Crashed in September 1921

Avro 534B
Version with plywood covered fuselage and shorter span lower wing.
Only one built. Crashed in August 1920.

Avro 534C
Version with reduced span wings for the 1921 Aerial Derby. Crashed in September 1922.

Avro 534D
Special version with modifications, to the order of Colonel E. Villiers, who used it for business trips around Calcutta until 1929.

Avro 543
Two-seat version with forward fuselage lengthened by 2 ft 6 in / 0.76m. later re-engined with 60 hp / 45 kW A.D.C. Cirrus engine and used until 1934.

Avro 554
Photo-survey version mounted on twin floats for the 1921 Shackleton-Rowett South Polr Expedition. Powered by an 80 hp / 60 kW Le Rhone rotary.

Avro 534
Engine: 1 x 35hp / 26 kW Green
Wingspan: 7.62 m / 25 ft 0 in
Length: 5.33 m / 17 ft 6 in
Height: 2.31 m / 7 ft 7 in
Wing area: 16.72 sq.m / 179.97 sq ft
Take-off weight: 395 kg / 871 lb
Empty weight: 280 kg / 617 lb
Max. speed: 129 km/h / 80 mph
Cruise speed: 113 km/h / 70 mph
Service ceiling: 12,000 ft / 3660 m
Range: 322 km / 200 miles