Armstrong Whitworth Ensign

The Armstrong Whitworth Ensign was a British four-engine airliner built during the 1930s for Imperial Airways. It could seat 40 passengers and was designed for European and Asian routes, connecting Britain with further seaplane flights to Australia and South Africa.

In the Second World War, they were used for transport duties to and from the area of Middle East command. After the war, they were withdrawn from service but - with no buyers forthcoming - scrapped.

Design and development
Armstrong Whitworth Aircraft started on the A.W.27 Ensign in 1934 after receipt of a specification from Imperial Airways for a monoplane airliner with four Armstrong Siddeley Tiger engines. Government policy was to send all first-class mail by air and Imperial Airways were increasing their fleet. The first aircraft was ordered in September for a cost of £27,000 (design) and £43,300 (manufacture) of that year, with delivery expected in 1936. Eleven more (at £37,000 each) were ordered in May 1935. An order for a further two aircraft (£40,000 each) in December 1936 brought the total to 14.

The Ensign was a high-wing cantilever monoplane of light alloy construction and an oval, semi-monocoque fuselage with a conventional tailplane. The wings aft of the single box spar were fabric covered as was the tailplane and fin. It had retractable landing gear and a castoring tail wheel. The main landing gear was hydraulically operated and retracted into the inner engine nacelles. The cockpit had side-by-side seating for two pilots with dual controls; there was also accommodation for a radio operator. The fuselage was divided into separate cabins, either four cabins with accommodation for 40 passengers or three cabins with room for 27 by day or 20 at night with sleeping accommodation.

Production of their Whitley heavy bomber for the Royal Air Force was a priority, and work on the Ensign proceeded slowly. Construction took place not at the main Coventry factory, but at the production line of Air Service Training Ltd (another member of the Hawker-Siddeley group) in Hamble. Constant changes were requested by Imperial, slowing production further. As a result, the Ensign's maiden flight did not take place until 24 January 1938. The first flight showed a problem with applying full rudder that was cured by modifying the servo. On the second, the undercarriage was retracted for the first time. The prototype then went on for more exhaustive tests before passing to the A&AEE for Air Ministry testing. On her fourth flight, the engines cut out due to incorrect settings of the fuel cocks and it had to be glided down to RAF Bicester where it made a perfect "dead-stick" landing. Imperial Airways named the prototype "Ensign" and as such the "Ensign class" was applied to the whole fleet. The aircraft were fitted out for either Empire routes (eight aircraft) or European routes (four aircraft). The former carried 27 passengers in three cabins or 20 sleeping; the latter 40 passengers across three cabins and a four-person "coupe" aft of the third cabin. The only difference in crewing was a "flight clerk" replacing one of the two stewards on Empire routes.

Despite being underpowered, the aircraft was certified, and full airline service began between Croydon Airport and Paris, France in October of that year.

Operational history
Three more Ensigns - Egeria, Elsinore and Euterpe - were completed by Christmas 1938, and were dispatched to Australia with the holiday mail. All three suffered mechanical problems and did not reach their destination; consequently, all five Ensigns were removed from active airline service and returned to Armstrong for improvements. Reliability was improved, and more powerful (935 hp) Armstrong Siddeley Tiger IXC engines aided performance somewhat. The aircraft were delivered back to the airline starting in June 1939 along with the sixth to be built.

The plan to use four Ensigns with Indian Trans-Continental Airways operating from Calcutta did not come to pass due to the modifications and the onset of war although registrations and new nmes had been made and in one case painted on the aircraft.

Eleven aircraft were in service at the outbreak of the Second World War, with a 12th following soon after, and all were withdrawn in October 1939; they were to be camouflaged before flying a new route from Heston Aerodrome to Le Bourget Airport, Paris. The aircraft remained in service after formation of BOAC that November but instead of being taken up for military service remained civilian under direction of National Air Communications. Their first duties following the German invasion of the Low Countries was ferrying supplies to France. This was followed by evacuation before France capitulated in June. Despite operating away from their maintenance base for weeks at a time, Ensigns managed 100% availability and impressed with their short take-off run even when fully loaded.

Three Ensigns were destroyed by enemy action in 1940 (G-ADSX Ettrick and G-ADSZ Elysian in France, and G-ADTC Endymion at Bristol Whitchurch in November 1940). G-ADSX Ettrick, which had been abandoned at Le Bourget after being damaged by bombs on 1 June 1940, was rumoured to have been used by the Germans, and later given Daimler-Benz engines. This is considered by most experts on the Luftwaffe to be a myth which may have its roots in a Flight article by P.W. Moss in 1957.

As the aircraft were found to be lacking in performance, it was decided to give the remaining eight aircraft Wright Cyclone G.102A engines.

The final two aircraft that had been ordered by Imperial in 1936 were equipped with more powerful Wright Cyclone geared radial engines and completed as A.W.27A Ensign Mk 2s. The new engines significantly improved performance and allowed the Ensign to be used in hot climates and at high altitude. At the same time other modifications were incorporated and the prototype Mark 2, Everest first flew in June 1941, with Enterprise following at the end of October.

All eight surviving airframes were upgraded with these newer engines in 1941-43, as they were completed they were transferred to the Middle East and worked for BOAC on Africa to India routes.

Ensigns flew throughout the war. On a ferry flight to west Africa, following trouble with her engines "Enterprise" made a force landing in the desert in French West Africa (at that point under Vichy France control) about 300 miles short of their destination. Codebooks and other paperwork on board was destroyed except that required to show the crew were civilian. They were picked up by an RAF Sunderland flying boat and taken on to Bathurst in Gambia. Enterprise was found by the French authorities, repaired and used as a hospital plane at Dakar before being flown to Vichy France. After the German occupation of Vichy France, she was taken by the German Air Ministry and tested before being used as transport for officers. It was scrapped in Toulouse in 1943. Several were broken up for spare parts to support the remaining fleet.

From 1944 under the end of their service, the Ensigns were used between Cairo and Calcutta. When taken out of use for their Certificate of Airworthiness overhauls, the camouflage dope - which in combination with the heat had been rotting the fabric surfaces - was removed and thereafter the Ensigns were in a "natural" finish.

After the end of the war, due in part to their performance and the problematic maintenance of the fabric services, it was decided eventually to remove the Ensigns from service and to return them to the UK. Euterpe which had been out of use since February 1945 was sacrificed to make repairs to the others.

The final Ensign passenger flight took place in June 1946 when Eddystone flew from Cairo to Hurn via Marseille; she had been delayed in the Middle East by repairs. Conversion of the Ensigns was considered and they were offered for sale but the projected costs were too much for those who showed interest. The aircraft were broken up at Hamble in March and April 1947 and removed to Cowley, Oxford where they were reduced to scrap.

Accidents and incidents

 * On 23 May 1940, G-ADTA Euryalus crash-landed at RAF Lympne and was damaged. The aircraft was one of six that escaped after a Luftwaffe raid on Merville Airfield, France. The intended destination was Croydon. Approaching the English coast, first, she lost her port inner engine and the pilot set course for RAF Hawkinge. A short time later, her starboard inner engine also had to be shut down. The pilot changed course for Lympne. On landing, the starboard undercarriage was not fully down, causing the wing to scrape the ground and the aircraft to go through a fence as no braking was attempted. Euryalus was flown to RAF Hamble in June, but it was decided to cannibalise her to repair G-ADSU Euterpe which had been damaged in an accident at Bonnington on 15 December 1939. Euryalus was officially written off on 15 November 1941 and scrapped in September 1942.

Variants

 * A.W.27 Ensign I
 * Four-engine medium-range transport aircraft. Powered by four 850 hp (630 kW) Armstrong Siddeley Tiger IXC radial piston engines.


 * A.W.27A Ensign II
 * Four-engine medium-range transport aircraft. Powered by four 950 hp (710 kW) Wright GR-1820-G102A Cyclone radial piston engines.

Civil operators

 * Air France
 * British Overseas Airways Corporation (BOAC)
 * Imperial Airways
 * British Overseas Airways Corporation (BOAC)
 * Imperial Airways

Military Operators

 * 🇫🇷 Vichy France
 * Armée de l'Air de Vichy
 * Royal Air Force
 * No. 24 Squadron RAF
 * No. 24 Squadron RAF