Tag Archives: Roy Chadwick

9 January 1941

BT308, the Avro Lancaster prototype, at RAF Ringway, 9 January 1941. (Avro Heritage Museum)
Captain Harry Albert (“Sam”) Brown, O.B.E. (Photograph courtesy of Neil Corbett, Test & Research Pilots, Flight Test Engineers)

9 January 1941: Test pilot Captain Harry Albert (“Sam”) Brown, O.B.E., (1896–1953) makes the first flight of the Avro Lancaster prototype, BT308, at RAF Ringway, Cheshire, England, south of Manchester.

Throughout World War II, 7,377 of these long range heavy bombers were produced for the Royal Air Force. The majority were powered by Rolls-Royce or Packard Merlin V-12 engines—the same engines that powered the Supermarine Spitfire and North American P-51 Mustang fighters.

The bomber was designed by Roy Chadwick, F.R.S.A., F.R.Ae.S., the Chief Designer and Engineer of A. V. Roe & Company Limited, based on the earlier twin-engine Avro Manchester Mk.I. Because of this, it was originally designated as the Manchester Mk.III, before being re-named Lancaster. Chadwick was appointed Commander of the Most Excellent Order of the British Empire, 2 June 1943, for his work.

The first prototype, BT308, was unarmed and had three small vertical fins.

Avro 683 Lancaster prototype BT308, shortly after the first flight at Manchester, 9 January 1941. (A.V.Roe via R.A.Scholefield) Photograph used with permission.
Avro 683 Lancaster prototype BT308, shortly after the first flight at RAF Ringway, Manchester, England, 9 January 1941. (A.V.Roe via R.A.Scholefield) Photograph is from The R.A. Scholefield Collection and is used with permission.

With the second prototype, DG595, the small center vertical fin was deleted and two larger fins were used at the outboard ends of a longer horizontal tailplane. DG595 was also equipped with power gun turrets at the nose, dorsal and ventral positions, and at the tail.

Avro Lancaster DG595, the second protoype of the Royal Air Force four-engine heavy bomber. This armed prototype has the twin-tail arrangement of the production aircraft. (Unattributed)
Avro Lancaster DG595, the second protoype of the Royal Air Force four-engine long range heavy bomber. This armed prototype has the twin-tail arrangement of the production aircraft. (Test & Research Pilots, Flight Test Engineers)
Air Ministry clearance form for Avro 638 Lancaster BT308. Shown on page 1 are the aircraft's engine type and serial numbers.
Air Ministry clearance form for Avro 683 Lancaster BT308. Shown on page 1 are the aircraft’s engine type and serial numbers.
Air Ministry test flight clearance form, Page 2.
Air Ministry test flight clearance form, Page 2. This form is signed by the airplane’s designer, Roy Chadwick, 5 January 1941.

The first production model, Lancaster Mk.I, was operated by a crew of seven: pilot, flight engineer, navigator/bombardier, radio operator and three gunners. It was a large, all-metal, mid-wing monoplane with retractable landing gear. It was 68 feet, 11 inches (21.001 meters) long with a wingspan of 102 feet, 0 inches (31.090) meters and an overall height of 19 feet, 6 inches (5.944 meters). The Mk.I had an empty weight of 36,900 pounds (16,738 kilograms) and its maximum takeoff weight was 68,000 pounds (30,909 kilograms).

BT308 and early production Lancasters were equipped with four liquid-cooled, supercharged, 1,648.96-cubic-inch-displacement (27.01 liter), Roll-Royce Merlin XX single overhead camshaft (SOHC) 60° V-12 engines, which were rated at 1,480 horsepower at 3,000 r.p.m. to 6,000 feet (1,829 meters). The Merlins drove three-bladed de Havilland Hydromatic quick-feathering, constant-speed airscrews (propellers), which had a diameter of 13 feet, 0 inches (3.962 meters), through a 0.420:1 gear reduction.

DG595 was used for performance testing at the Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down. The Mark I had a maximum economic cruise speed of 267 miles per hour (430 kilometers per hour) at 20,800 feet (6,340 meters), and a maximum speed of 286 miles per hour (460 kilometers per hour) at 20,000 feet (6,096 meters) at a gross weight of 45,300 pounds (20,548 kilograms).¹ Its service ceiling was 20,000 feet (6,096 meters) at 64,500 pounds (29,257 kilograms). It had a range of  2,530 miles (4,072 kilometers) with a 7,000 pound (3,175 kilogram) bomb load.

The Lancaster was designed to carry a 14,000 pound (6,350 kilogram) bomb load, but modified bombers carried the 22,000 pound (9,979 kilogram) Grand Slam bomb. For defense, the standard Lancaster had eight Browning .303-caliber Mark II machine guns in three power-operated turrets, with a total of 14,000 rounds of ammunition.

According to the Royal Air Force, “Almost half all Lancasters delivered during the war (3,345 of 7,373) were lost on operations with the loss of over 21,000 crew members.”

Only two airworthy Avro Lancasters are in existence.

The Royal Air Force Battle of Britain Memorial Flight Avro Lancaster Mk.I, PA474. This airplane was built in 1945 by Vickers Armstongs Ltd. at Broughton, Wales, United Kingdom. (Battle of Britain Memorial Flight)
The Canadian Warplane Heritage Museum’s Avro Lancaster Mk.X FM213, flies formation with an Royal Canadian Air Force CF-188 Hornet. The bomber is marked VR A and nicknamed “Vera.” FM213 was built by Victory Aircraft Ltd., Malton, Ontario, Canada. (Canadian Warplane Heritage Museum)

¹ Speeds shown are True Air Speed (T.A.S.)

© 2019, Bryan R. Swopes

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17–22 November 1946

Avro Lancastrian C.1 VH742 after installation of Rolls-Royce RB.41 Nene Mk.I gas turbine engines. The inboard Merlin engines have been shut down and their propellers feathered. (Royal Air Force)

17 November 1946: A modified Avro 691 Lancastrian C.1, VH742, under the command of Rolls-Royce’s chief test pilot, Captain Ronald Thomas Shepherd, O.B.E., flew from London Heathrow Airport (LHR) to Aéroport de Paris – Le Bourget (LBG) for 17th Salon de Aviation (Paris Air Show) with two Rolls-Royce RB.41 Nene Mk.I turbojet engines for propulsion. The airplane’s two Rolls-Royce Merlin V-12 piston engines were shut down, except for takeoff and landing, and their three-bladed propellers were feathered to reduce drag. It was the first-jet-powered passenger transport to fly from one country to another.

A contemporary aviation industry news article described the event:

The Nene-Lanc, Flies to Paris

THE flight of the Nene Lancaster from London to Paris last Monday, to play its part in connection with the exhibition, may be said to have marked a historic part in British aircraft development, for it constituted the first time that any jet-powered airliner had flown from one country to another. Moreover, since this particular aircraft has been flying fairly regularly since round about the time of the Radlett exhibition, the flight to Paris was no special performance, but merely one more public demonstration of its inherent reliability.

In the hands of Capt. R. T. Shepherd, chief test pilot for Rolls-Royce, the “Nene-Lanc” landed at Le Bourget at 10.58 a.m., G.M.T., after a 50-minute flight from London Airport, giving an average speed of 247.5 m.p.h. [398.3 kilometers per hour] Two passengers were carried in addition to the crew; they were Mr. Roy Chadwick, the Avro designer, and Mr. R. B. William Thompson, Chief Information Officer of the Ministry of Supply.

Capt. Shepherd said that he was very pleased with the aircraft’s performance and added that, but for having to circle Le Bourget Airport Twice before landing, the flight would have been completed in 43 minutes.

FLIGHT and AIRCRAFT ENGINEER, No. 1978. Vol. L., Thursday, November 21st, 1946 at Page 561, Column 2.

Five days later, VH742 flew back to England:

Return Trip

THE return of the Nene Lancastrian on Nov. 22nd, direct from Le Bourget to Heathrow, was made in only 49 min, including landing, actual flying time from point to point being 41 min—an average speed of 322 mp.h. [518.2 kilometers per hour] This remarkable performance was in spite a beam wind and the dead weight and drag of the two inboard Merlins, which are only used for takeoff and landing.

Passengers of the return trip included Mr. Roy Chadwick, chief designer and a director of A. V. Roe and Co., Air Comdre. Kirk and Air Comdre. Pike.

FLIGHT and AIRCRAFT ENGINEER, No. 1979., Vol. L., Thursday, November 28th, 1946 at Page 588, Column 1.

Avro Lancastrian (nene engine test bed). © IWM (ATP 14764B)
Avro Lancastrian C.1 VH742 with Rolls-Royce Nene engines. © IWM (ATP 14764B)

The Rolls-Royce RB.41 Nene engine first been run in October 1944. It  installed in a Lockheed YP-80A Shooting Star, 44-83027, and the engine was first flown 18 July 1945 with Rolls-Royce test pilot Wing Commander John Harvey Heyworth, A.F.C., in the cockpit. The Nene-powered P-80 had made approximately 30 test flights when it was damaged beyond repair at RAF Syerston, 6 December 1945. With test pilot Andy McDowall flying, a fractured fuel pipe caused the engine to flame out from fuel starvation. McDowall tried to glide to a landing but another airplane was on the runway. He touched down on the grass but the landing gears were pushed up through the Shooting Star’s wings.

The jet fighter had been too small to allow for adequate test equipment. A larger aircraft was needed. The R.A.F. assigned VH742 the role of test aircraft.

The new Lancastrian arrived at the Rolls-Royce Flight Test Establishment at Hucknall Aerodrome, Nottinghamshire, 30 October 1945. The modification was engineered and the airplane was modified. The Lanc’s two outboard Rolls-Royce Merlin V-12 engines were removed and two Nene Mk.I engines were installed in underslung nacelles. The wing flaps were shortened by 3 feet, 4 inches (1.016 meters) and the ailerons by 10 inches (0.254 meters) to provide clearance from the jet engines’ exhaust. Sheet steel was installed on the lower surfaces of the wings as protect against the heat.

Three fuel tanks were installed in each of the Lancastrian’s wings. The center tank contained gasoline for the Merlin engines, while the inner and outer tanks, plus two auxiliary tanks in the fuselage, carried kerosene for the jet engines. Fuel capacity was 760 gallons (2,877 liters) of gasoline and 2,420 gallons (9,161 liters) of kerosene.

In the Lancastrian’s cockpit, additional instruments were installed for the turbojets: tachometers reading from 0–20,000 r.p.m.; oil pressure gauges, 0–80 p.s.i.; exhaust gas temperature, 400˚–750 ˚C., and exhaust gas pressure.

The first flight of the modified VH742 took place 14 August 1946, with Ronnie Shepherd in the cockpit. Running on the jet engines alone, the airplane was extraordinarily quiet and vibration free. Like all early turbojets, the Nenes were slow to accelerate from low r.p.m. Test pilots had to use caution. Jim and Harvey Heyworth also flew VH742 during the last half of August.

RB.41 Nene. (Rolls-Royce)
RB.41 Nene. (Rolls-Royce)

The Rolls-Royce RB.41 Nene Mk.I was developed from the earlier RB.40 Derwent.¹ It was considerably larger and produced nearly double the thrust. It was a single-stage centrifugal-flow compressor/single-stage axial-flow turbine, rated at 5,000 pounds of thrust (22.24 kilonewtons) at 12,400 r.p.m. for takeoff.

A second Nene-powered Lancastrian was added to the test fleet at Hucknall the following year. Last Nene flight took place in August 1949.

VH742 had been ordered by the Royal Air Force during World War II as an Avro Type 683 Lancaster B. Mk.III, a very long range heavy bomber, and assigned identity markings PD194. With the end of World War II in Europe, orders for hundreds of Lancaster bombers were cancelled. The partially completed PD194 was modified on the assembly line as a Lancastrian C. Mk.I passenger transport and renumbered as VH742.

The Avro Type 691 Lancastrian was a four-engine civil transport based on the World War II very long range heavy bomber, the Avro Lancaster. The airliner was operated by a flight crew of four and carried one flight attendant. It could carry up to thirteen passengers. The Lancastrian was 76 feet, 10 inches (23.419 meters) long with a wingspan of 102 feet (31.090 meters) and overall height of 19 feet, 6 inches (5.944 meters). The empty weight was 30,220 pounds (13,707.6 kilograms) and gross weight was 65,000 pounds (29,483.5 kilograms).

The Lancastrian Mk.III was powered by four 1,648.9-cubic-inch-displacement (27.04 liter) liquid-cooled, supercharged, Rolls-Royce Merlin T24/2 single overhead camshaft (SOHC) 60° V-12 engines producing 1,650 horsepower and turning three bladed propellers.

The airplane a cruise speed of 245 miles per hour (394.3 kilometers per hour) and a maximum speed of 315 miles per hour (506.9 kilometers per hour). The service ceiling was 25,500 feet (7,772 meters) and the range was 4,150 miles (6,679 kilometers).

Rolls-Royce test pilots (left to right) Wing Commander John Harvey Heyworth, AFC; Squadron Leader Alexander James Heyworth, DFC and Bar, FRAeS; Captain Ronald Thomas Shepherd, OBE; Wing Commander Andrew McDowall, DSO, AFC, DFM; and Herbert Clifford Rogers, OBE, DFC; with Merlin 632/ Avon-powered Avro Lancastrian C.2 VL970, circa 1949. Each one of these men served as Chief Test Pilot for Rolls-Royce. (Rolls-Royce)
Rolls-Royce test pilots (left to right) Wing Commander John Harvey Heyworth, A.F.C.; Squadron Leader Alexander James Heyworth, D.F.C. and Bar, FRAeS; Captain Ronald Thomas Shepherd, O.B.E.; Wing Commander Andrew McDowall, D.S.O., A.F.C., D.F.M.; and Herbert Clifford Rogers, O.B.E., D.F.C.; with Merlin 632/ Avon-powered Avro Lancastrian C.2 VL970, circa 1949. Each one of these men served as Chief Test Pilot for Rolls-Royce. (Rolls-Royce)

91 Avro Lancastrians were built, including modified Lancaster bombers. The transport variant first flew in 1943. In addition to the Royal Air Force, commercial Lancastrians were operated by British European Airways, British Overseas Airways Corporation and British South American Airways. The last one was retired in 1960.

Rolls-Royce built more than 1,100 RB.41 Nene engines. It was licensed for production by Pratt & Whitney as the J42. Forty Nenes were sold to the Soviet Union under the condition that they would not be used for military purposes. These were reverse-engineered and produced as the Klimov RD-45 which powered the Mikoyan-Gurevich MiG-15 fighter.

¹ While Rolls-Royce named its piston-driven aircraft engines after birds of prey, the turbojet engines were named for rivers.

© 2018, Bryan R. Swopes

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