Vickers Viastra

Vickers

Industry	Aerospace
Founded	1828 in United Kingdom
Products	Aircraft

Template:Infobox aircraft The Vickers Viastra was a high-wing monoplane constructed entirely from metal, designed to carry twelve passengers. It was produced in several engine configurations including single, twin, and tri-motor versions. Two twin-engine Viastras were operated commercially in Australia between 1931 and 1936, while another example served as an official Royal transport.

Development

The construction technique employed in the Viastra was derived from the patents of Michel Wibault, who began collaborating with Vickers in 1922. This method enabled the manufacture of an all-metal airframe using straightforward, unmachined metal components covered by very thin corrugated light alloy sheets approximately 0.016 inches (0.4 mm) thick. The skin panels were riveted both to each other and to an underlying framework; however, the wing skins were not load-bearing. Vickers' initial use of this approach was on the licensed-built Wibault Scout. The first original Vickers design applying this method was the Vickers Vireo, followed by the third design, the Viastra, which combined aspects of both Wibault and traditional Vickers construction practices.

Conceived as a commercial aircraft capable of operating with either one or three engines, the Viastra was intended to accommodate ten passengers and was designed particularly for use in regions with limited ground transportation infrastructure. Several variants were produced by Vickers that were largely similar except for their powerplants; ultimately, models featured one, two, or three engines. These were high-wing monoplanes with wings of constant chord and square tips, employing a thick Raf 24 airfoil section. Like the rest of the aircraft, the wings were covered with corrugated skin and equipped with balanced ailerons and outboard slots. The tail assembly was a biplane configuration consisting of two narrow-chord horizontal surfaces—the lower attached beneath the fuselage and the upper positioned well above it. The main rudders were narrow vertical fins located at the wingtips; single- and tri-engine variants also included a small triangular central fin housing an auxiliary rudder and supporting the upper horizontal tailplane. In contrast, most twin-engine models replaced this central fin and rudder with tubular bracing.

The fuselage featured a square cross-section that remained parallel through the passenger cabin before tapering toward the tail. Six rectangular windows lined each side of the passenger compartment, while the crew occupied an enclosed cockpit situated ahead of the wing leading edge. Each wing was supported by a pair of parallel struts connecting to the lower fuselage; the forward strut also served as a mounting point for a main undercarriage leg reinforced by additional bracing. On twin- and tri-motor versions, outer engines were installed just below the wings and enclosed within narrow-chord Townend ring cowlings. Conversely, central engines on tri-motor models and single-engine variants were left uncowled.

Operational history

The initial Viastra, bearing the registration G-AAUB and equipped with three 270 hp (200 kW) Armstrong Siddeley Lynx Major 7-cylinder radial engines, completed its maiden flight on 1 October 1930. Subsequently, two Viastra II models were introduced and operated on the Perth to Adelaide route by West Australian Airways starting in March 1931. One of these aircraft was lost due to a landing mishap in 1933, while the other remained active until 1936. Both were configured to seat twelve passengers and initially powered by a pair of 525 hp (390 kW) Bristol Jupiter XIF radial engines. However, they occasionally flew with one or two Jupiter VI engines because the more powerful XIF variants exhibited reliability issues. The Australian experience revealed that the twin-engine Viastra II lacked sufficient power to maintain altitude on a single engine. This limitation was verified by Vickers when they replaced the Lynx engines on G-AAUB with Jupiter VIFM engines, resulting in the aircraft being redesignated as the Viastra VIII. One of the two West Australian Airways planes was temporarily converted into a Viastra IX, featuring engines mounted 15 inches (380 mm) lower before being reverted back to a Viastra II configuration. West Australian Airways also placed an order for a single-engine Viastra powered by a Jupiter XIF; however, this order was canceled—likely due to concerns over engine reliability—and the aircraft remained in the United Kingdom.

Between its periods powered by tri-motor Lynx and Jupiter engines, G-AAUB operated briefly as a twin-engine Viastra III fitted with Armstrong Siddeley Jaguar VIc radial engines (470 hp / 350 kW, 14-cylinder), sharing similarities with the Viastra II. The Viastra X, registered G-ACCC, was a unique twin-engine model powered by Bristol Pegasus IIL3 nine-cylinder radials, constructed as an opulent "Royal barge" for the Prince of Wales. This aircraft featured a spatted landing gear, an under-fuselage pannier, and a central fin and rudder arrangement typically seen only on odd-numbered engine variants. It first flew in April 1933 but saw limited use as a royal transport. The aircraft participated in the 1934 Hendon RAF display adorned in royal colors and was subsequently used until 1937 for airborne radio testing, providing wireless operators with an unusually luxurious environment.

An additional Viastra was produced incorporating a newly designed lightweight wing by B. E. Wallis. This model was delivered to the Royal Aircraft Establishment at Farnborough for structural evaluation; however, there is no evidence it ever achieved flight. It was not assigned an official Viastra variant number.

Variants

Viastra I (Type 160)

Prototype ten-passenger model featuring three Armstrong Siddeley Lynx V engines; one unit built registered as G-AUUB, later converted into a twin-engine Viastra III and subsequently reverted to a three-engine configuration as the Viastra VIII.

Viastra II (Type 198)

Twelve-seat passenger version intended for West Australian Airways powered by two Bristol Jupiter XIF engines; two units produced.

Viastra III (Type 199)

Conversion of the original Viastra I fitted with two Armstrong Siddeley Jaguar VIc engines; later modified back into a three-engine setup designated as Viastra VIII.

Viastra VI (Type 203)

Single-engine cargo variant equipped with a Bristol Jupiter XIF engine; one built but never delivered.

Viastra VIII (Type 220)

Modification of the Viastra III featuring three Bristol Jupiter VIFM engines.

Viastra IX (Type 242)

Short-term alteration of a Viastra II with lowered engine mounts.

Viastra X (Type 259)

Seven-passenger VIP configuration for the Prince of Wales powered by two Bristol Pegasus radial engines; one unit constructed registered G-ACCC.

Wallis-Viastra (Type 256)

Incorporated new wing design by B. E. Wallis; possibly never flown; one built.

Specifications (Viastra II)

File:Vickers Viastra 3-view NACA Aircraft Circular No.129.jpg

Three-view illustration of the Vickers Viastra from NACA Aircraft Circular No.129

External links

• Vickers "Viastra I", Flight, 26 September 1930