Rolls-Royce Eagle II / H-24

This was the last of the line of reciprocating, liquid-cooled units. The initial design project was conceived toward the end of 1942 as the necessity for a higher-powered engine was foreseen. The Rolls-Royce design team realised that producing a scaled-up version of their Griffon V-12 engine would lead to excessively large combustion chambers and problems with detonation.

Considerations of aspiration and flame travel set a more or less effective limit of about 6 inches to bore size, and with cylinders of this order it has been established that 12 pistons per crankshaft is about the practical limit and considered an X-24 design. This layout had previously caused unreliability with the Rolls-Royce Vulture due to the need to fasten four connecting rods in a complicated arrangement to a common big end bearing.

The designers finally settled on an ‘H’ layout with two crankshafts and ‘blade and fork’ connecting rod attachments, the crankshafts being connected through the propeller speed reduction unit. Sleeve valves were decided upon in view of the fact that they offer advantages over poppet valves from the aspect of maintenance and obviation of adjustment.

The case is split vertically into port and starboard halves of cast light alloy, the front wall carrying the tail bearings for the timing gears uniting the crankshafts. Cylinder blocks are also examples of sandcasting technique in light alloy, the upper and lower rows of cylinders on each side being formed in one casting. Each cylinder is ventilated with three inlet and two exhaust ports, the latter ports of each vertical pair of cylinders discharging to a common pair of ejector stacks.

Sleeve drive is by a worm shaft on each side commonly serving top and bottom rows of sleeves, each shaft running in six split plain bearings.

A two-speed, two-stage supercharger and intercooler were used to compress then cool the air-fuel mixture, following Griffon and Merlin practice. Starting was by Coffman starter. An auxiliary shaft driven by the lower crankshaft operated the main coolant pump, intercooler coolant pump, pressure and scavenge oil pumps and a fuel injection pump. Piston ring failures and cylinder head sealing problems were experienced during early flight testing.

Rolls-Royce Eagle 22

It was designed and built in the early-1940s and first ran in March 1944. The Eagle was never fitted to a production front-line fighter, as it was overshadowed by a new wave of turbojet engines, such as the Rolls-Royce Derwent and turboprops such as the Dart and Armstrong Siddeley Python. Fifteen Eagle 22s were produced to power the prototypes of the Westland Wyvern fighter / torpedo bomber as its intended powerplant, the AS Python was late in development.

Early Eagles (I and II) drove a single airscrew, but the Eagle 22 was arranged for contraprops in view of its application to the Westland Wyvern T.F.1 deck-landing strike fighter. In M. S. gear the Eagle delivered 3,415 h.p. at 3,500 r.p.m. for take-off. The maximum power rating in M. S. gear was 3,500 h.p. at 3,250 ft, and in F. S. gear, 3,020 h.p. at 15,250 ft.

Variants:
46H Eagle I
(1944) – Compression ratio 6.5:1

46H Eagle II
(1944) – Modified Eagle I

46H Eagle (20 srs) 22
(1946-1949) – Increased compression ratio (7:1), Fifteen engines produced at the Derby Rolls-Royce factory. First flown in a Westland Wyvern on 16 December 1946.

Specifications:
Eagle 22
Type: 24-cylinder liquid-cooled H-type aircraft piston engine
Bore: 5.4 in (137 mm)
Stroke: 5.125 in (130 mm)
Displacement: 2,807 in³ (46 L)
Length: 135.5 in (3442 mm)
Width: 43.4 in (1,102 mm)
Height: 50.0 in (1,270 mm)
Dry weight: 3,900 lbs (1,769 kg)
Valvetrain: Sleeve valves
Supercharger: Two-speed, two-stage supercharger, maximum boost +18 lb
Fuel type: 115/150 Octane petrol, DERD 2476
Cooling system: Liquid-cooled, 70% water, 30% ethylene glycol
Reduction gear: Geared spur, 0.2985:1 reduction ratio. contra-rotating right-hand/left-hand tractor
Power output: 3,200 hp (2,387 kW) at 18 lb (124.1 kPa) of boost at 3,500 rpm
Specific power: 1.13 hp/in³ (51.7 kW/L)
Compression ratio: 7:1
Power-to-weight ratio: 0.82 hp/lb

Rolls-Royce Eagle

Eagle VIII

The Eagle was designed by Henry Royce in collaboration with his chief assistant, A. G. Elliott. It set the pattern for the smaller Falcon and the larger Condor, and in improved forms continued in service from 1917 until the 1930s.

Though designed for only 200 h.p., the first example was run in October 1915 (less than six months after work on the drawings had been started at Derby) at a brake horsepower of 225.

By March 1916 the new engine was delivering 266 b.h.p.; by July 284 h.p.; and by December 322 h.p. By September 1917 the figure had risen to 350 h.p.; in Feburary 1918 it had reached 360 h.p. An official Rolls-Royce instruction book dated December 1917 ascribes the following outputs (at normal r.p.m.) to the various series: Eagle 1, 225 b.h.p.; Eagle If, 266; Eagle Ill, 284; Eagle IV, 284; Eagle V, 322; Eagle VI, 322; Eagle VII, 322; and Eagle VIII, 350. These variants differed in the type and number of carburettors, in jet size, in the pattern of inlet pipes and pistons, and other details. By far the most famous among them was the Eagle VIII, which powered such fine aircraft as the Phomix Cork, Felixstowe F.3 and F.5, the D.H.4, 9A, 9B, 10B and IOC, the Fairey IIIC and IIII), the Handley Page 0/400 and V/1500, the Short Shirl, and the Vickers Vimy and Vernon. Other military installations were made in the Wight seaplane, F.E.2D, REA, R.E.7, Porte Baby, F.2, Felixstowe Fury (F.4), D.H.10, Fairey F.16 and F.17 Campania, Handley Page 0/100 and Vickers Vim. Civil applications included the D.H.16 and Handley Page W.8b.

Irrespective of series number, the Eagle was a twelve-cylinder, water-cooled, 60-deg vee of 20.32 litres capacity. Each cylinder, with its water-jacket, formed a separate unit; the barrel, machined from a steel forging, was retained by a base flange and studs. Inlet and exhaust ports were machined from solid forgings, welded-in at opposite sides of the head, and the water-jacket was fabricated from steel pressings, welded in place.
There was one inlet and one exhaust valve for each cylinder, and a single camshaft, carried in a casing along each bank of cylinders, operated both. There were two sparking plugs per cylinder, served, on the earlier engines, by four six-cylinder magnetos and on the later series by two twelve-cylinder magnetos.

A contemporary Rolls-Royce description continues: “The oil consumption should be taken as 1 gallon per hour. . . . The lubrication system is of the type in which one oil pump supplies pressure oil to the main bearings and other parts, while one scavenger pump evacuates the accumulation of oil in the crankcase to the oil tank. . . . The quantity of water carried in the cylinder water-jackets, water pipes, and pump is 3.1 gallons…. The Rolls-Royce carburettors are fitted with a control so that the delivery of petrol may be adjusted from the pilot’s seat. This not only serves as a means of correcting the effects of decreasing atmospheric pressure with increasing altitude, but can also be used to obtain extremely economical running, and also to obtain a rich mixture for starting…. All controls, e.g., throttle, altitude, and magneto, are brought to one common location on the engine, to facilitate connection to the plane…. The carburettor throttles are fitted with springs, which, in the event of a breakage of the control, are intended to open the throttles to the full extent.”

A special feature of the Eagle was the epicyclic reduction gear, for which the advantage was claimed that it imposed far less strain on the crankcase than would spur gearing. The gear was of fixed sunwheel type, in which an annulus, or internally toothed gearwheel, on the crankshaft meshed with three small spur gearwheels on the extremities of three arms formed integrally with the airscrew shaft. The three small gears were connected to three pinions which meshed with the fixed sunwheel, and the airscrew shaft was bolted to the three-armed spider which carried the planet pinion cage. An Oldharn coupling provided the anchorage of the sunwheel to the gear casing and allowed the gears to be perfectly aligned.

Late in 1922 Flight reported: “A recent model introduced by Rolls-Royce, Ltd., is the Eagle IX, which is generally similar to the famous Eagle VIII but differs from that type in certain details. The new model has been designed to be equally suitable for peace and war purposes, and to that end the following improvements have been effected: Two carburettors are fitted instead of four, so that tuning is considerably facilitated. The placing of the carburettors low down allows of using directgravity feed; the float feeds have been redesigned. The engine will now function satisfactorily with a ‘head’ of only 8in above the centre-line of the crankshaft. In view of the tendency m modern commercial aircraft of employing direct-gravity petrol feed from the main tanks in order to avoid pumps, piping, etc., this should be a great advantage, and should help to ensure for the Eagle IX as great popularity as that enjoyed by the previous model.”

In the Eagle XV the epicyclic gear was further modified by the insertion of an additional friction clutch and gearwheel in the train, making the existing friction anchorage into a manually controllable clutch and converting the gear from a single-speed to a two-speed type. In the absence of a variable-pitch airscrew this arrangement gave a considerable advantage.

The following data for the Eagle VIII are taken from Rolls-Royce Aero Engine Instruction Book, Eagle Series I – VIII and Falcon Series I, II and III. Air Board Technical Department Book No. 244, December 1917: Dry weight, 847 lb; normal r.p.m., 1,800; max. permissible r.p.m. (5 min only), 2,000; gear ratio, 0.60; b.h.p. at normal r.p.m., 350; petrol consumption in gal/hr, at sea level, normal r.p.m. and normal b.h.p., 23; carburettors, four R.R. C.H. (Rolls-Royce, Claudel Hobson), 42 mm; magnetos, four Watford; pistons, high compression, four rings (one at bottom).

In 1925 a little-known Eagle development-the 16-cylinder, 500 h.p. Mk XVI-made its appearance. It had a stroke of 441n instead of 61in. The Mk XX was a projected scaled-up version, but was never built.

Rolls-Royce Crécy

Sir Henry Tizard, Chairman of the Aeronautical Research Committee (ARC), was a proponent of a high-powered “sprint” engine for fighter aircraft and had foreseen the need for such a powerplant as early as 1935 with the threat of German air power looming. It has been suggested that Tizard influenced his personal friend Harry Ricardo to develop what eventually became known as the Rolls-Royce Crecy. The idea was officially discussed for the first time at an engine sub-committee meeting in December 1935.

“The Chairman remarked that if it was the desire of the Air Ministry to develop a type of sprint engine for home defence….there was the question as to how far fuel consumption could be disregarded. Mr Ricardo had raised this point in a recent conversation by enquiring whether a high fuel consumption might not be permissible under certain circumstances, for if so, an investigation of the possibilities of the two-stroke petrol engine appeared to be attractive.”
—Henry Tizard, The Rolls-Royce Crecy

Previous experience gained between 1927 and 1930 using two converted Rolls-Royce Kestrel engines through an Air Ministry contract had proven the worth of further research into a two-stroke sleeve-valved design. Both these engines had initially been converted to diesel sleeve-valved operation with a lower power output than the original design being noted along with increased mechanical failures, although one converted Kestrel was subsequently used successfully by Captain George Eyston in a land-speed record car named Speed of the Wind. The second engine was further converted to petrol injection which then gave a marked power increase over the standard Kestrel.

Single-cylinder development began in 1937 under project engineer Harry Wood using a test unit designed by Ricardo. Although originally conceived as a compression ignition engine, by the time Rolls-Royce started serious development, in conjunction with the Ricardo company, the decision had been taken by the Air Ministry to revert to a more conventional spark-ignition layout, although still retaining fuel injection.

The first complete V12 engine was built in 1941, designed by a team led by Harry Wood with Eddie Gass as the Chief Designer. Bore was 5.1 in (129.5 mm), stroke 6.5 in (165.1 mm), compression ratio 7:1 and weight 1,900 lb (862 kg). The firing angle was 30 degrees BTDC, and 15 lbf/sq.in (100 kPa) supercharger boost was typical. First run on 11 April 1941, in bench-testing it produced 1,400 horsepower (1,000 kW); however, there were problems with vibration and the cooling of the pistons and sleeves. The thrust produced by the exceptionally loud two-stroke exhaust was estimated as being equivalent to a 30% increase in power at the propeller on top of the rated output of the engine. The power of the engine was interesting in its own right, but the additional exhaust thrust at high- speed and altitude could have made it a useful stop gap between engines such as the Rolls-Royce Merlin and anticipated jet engines. Serial numbers were even, Rolls-Royce practice being to have even numbers for clockwise rotating engines when viewed from the front.

The reciprocating sleeve valves were open-ended rather than sealing in a junk head – the open end uncovered the exhaust ports high in the cylinder wall at the bottom of the sleeves’ stroke, leaving the ports cut into the sleeve to handle the incoming charge only. They had a stroke of 30% of the piston travel at 1.950 in (49.5 mm) and operated 15 degrees in advance of the crankshaft. The Crecy sleeve valves were of similar construction but differed in their operation compared to the rotary sleeve valve design that was pioneered by Roy Fedden, and used successfully for the first time in an aircraft engine, the Bristol Perseus, in 1932.

Unlike most two-stroke engines, supercharging was used rather than crankcase compression to force the charge into the cylinder – this also allowed for a conventional oil lubrication system instead of the total-loss type found in many two-stroke engines. Stratified charge was used where the fuel was injected into a bulb-like extension of the combustion chamber where the twin spark plugs ignited the rich mixture. Operable air-fuel ratios of from 15 to 23:1 were available to govern the power produced between maximum and 60%. The rich mixture maintained near the spark plugs reduced detonation allowing higher compression ratios or supercharger boost. Supercharger throttling was used as well to achieve idling. The supercharger throttles were novel vortex types, varying the effective angle of attack of the impeller blades from 60 to 30 degrees. This reduced the power required to drive the supercharger when throttled, and hence fuel consumption at cruising power.

Later testing involved the use of an exhaust turbine which was a half-scale version of that used in the Whittle W.1 turbojet, the first British jet engine to fly. Unlike a conventional turbocharger the turbine was coupled to the engine’s accessory driveshaft and acted as a power recovery device. It was thought that using the turbine would lower fuel consumption allowing the engine to be used in larger transport aircraft. This was confirmed during testing however failures due to severe overheating and drive shaft fractures were experienced.

Test summary
The following summarises the test running programme, hours run, and highlights some of the failures experienced.

Crecy 2

11 April 1941
First run. One-piece cylinder block/head. Testing stopped due to piston failure.
Hours run: 69

October 1942 – December 1942
Three rebuilds during this period, testing stopped after 35 hours due to piston seizure.
Hours run: 67

February 1943 – July 1943
Converted to Mk II configuration (separate cylinder heads), three rebuilds during this period. Air Ministry acceptance test passed.
Hours run: 38

March 1944 – July 1944
Five rebuilds during this period. Equal length injector pipes fitted, modified supercharger drive. Two failures, sleeve valve seizure and supercharger drive failure.
Hours run: 82

August 1944 – November 1944
Successful type test passed (112 hours). Post run inspection revealed cracked big-end bearings, pistons, reduction gear housing and sleeve valve eccentric drive bearing.
Hours run: 150

March 1945 – April 1945
Attempted endurance test, piston failure after 27 hours. Two rebuilds during this period.
Hours run: 49

(Total hours: 461)

Crecy 4

November 1941
No report available.
Hours run: 55

July 1942 – August 1942
Three rebuilds, successful 50-hour test, second 50-hour test abandoned after cylinder block failure due to cracking.
Hours run: 80

September 1942 – October 1942
Two rebuilds. Completed 25-hour test successfully, second test halted after four hours running due to sleeve valve failure.
Hours run: 55

(Total hours: 293)

Crecy 6

July 1943 – February 1944
First engine built as Mk II. Eight rebuilds during this period, failures included supercharger drive failure and sleeve valve eccentric drive bolt fracture.
Hours run: 126

May 1944 – September 1944
Four rebuilds. Supercharger flexible drive failure and sleeve valve seizure.
Hours run: 93

November 1944 – February 1945
Three rebuilds, main bearing failure, piston failure.
Hours run: 128

June 1945 – August 1945
One rebuild, endurance test halted after 95 hours due to sleeve valve drive failure, 40 hours run with a propeller fitted.
Hours run: 132

(Total hours: 481)

Crecy 8

September 1943 – March 1944
Eight rebuilds, endurance test successfully completed.
Hours run: 207

April 1944
Supercharger drive failure.
Hours run: 73

June 1944 – September 1944
Five rebuilds, no failures reported.
Hours run: 32

October 1944 – December 1945
Two rebuilds, piston failure, engine fitted with exhaust turbine.
Hours run: 22

(Total hours: 336)

Crecy 10

August 1944 – February 1945
Six rebuilds, melted inlet manifold after seven hours, sleeve valve seizure after a further four hours. Two injector pump failures.
Hours run: 53

March 1945 – June 1945
One rebuild, piston failure.
Hours run: 30

July 1945 – September 1945
Two rebuilds, exhaust turbine fitted, some running without supercharger. Sleeve valve and supercharger drive failure.
Hours run: 82

(Total hours: 166)

Crecy 12

January 1945 – October 1945
Four rebuilds, exhaust turbine fitted. Turbine failure, piston failure and sleeve valve drive failure.
(Total hours: 67)

The progress of jet engine development overtook that of the Crecy and replaced the need for this engine. As a result work on the project ceased in December 1945 at which point only six complete examples had been built, however an additional eight V-twins were built during the project. Crecy s/n 10 achieved 1,798 horsepower (1,341 kW) on 21 December 1944 which after adjustment for the inclusion of an exhaust turbine would have equated to 2,500 horsepower (1,900 kW). Subsequent single-cylinder tests achieved the equivalent of 5,000 brake horsepower (3,700 kW) for the complete engine. By June 1945 a total of 1,060 hours had been run on the V12 engines with a further 8,600 hours of testing on the V-twins. The fate of the six Crecy engines remains unknown.

If the Crecy had flown it would have done so using a Hawker Henley, L3385 which was delivered to Hucknall for conversion on 28 March 1943. This aircraft remained at Hucknall until 11 September 1945 when it was scrapped without ever having the engine fitted.

Two years prior to the Hawker Henley’s arrival (Summer 1941) a Supermarine Spitfire Mk II, P7674 had been delivered to Hucknall and was fitted with a Crecy mock-up to enable cowling drawings and system details to be designed. It had also been agreed that the first production Spitfire Mk III would be delivered to Hucknall in early 1942 minus its Merlin engine for fitment of an airworthy Crecy; this delivery did not occur however. A Royal Aircraft Establishment report (No. E.3932) of March 1942 estimated the performance of the Spitfire fitted with a Crecy engine and also compared this to a Griffon 61-powered variant of the type. The report stated that the Crecy’s maximum power output would be too much for the Spitfire airframe but that a derated version would have considerable performance gains over the Griffon-powered fighter.

Crecy
Type: 12-cylinder supercharged liquid-cooled 2-stroke aircraft piston engine
Bore: 5.1 in (129.5 mm)
Stroke: 6.5 in (165.1 mm)
Displacement: 1,536 cu.in (26 lt)
Dry weight: 1,900 lb (862 kg)
Valvetrain: Crankshaft-driven reciprocating sleeve valves
Supercharger: Gear-driven centrifugal type supercharger with variable angle of attack of the impeller blades providing up to 24 psi (165 kPa) of boost.
Turbocharger: Three engines fitted with exhaust turbine (50% scale version of Whittle W.1 turbine)
Fuel system: Direct fuel injection, 2 x CAV 6-cylinder pumps
Fuel type: 100 Octane petrol
Oil system: Gear pump
Cooling system: Liquid-cooled
Reduction gear: 0.451:1 (Left-hand tractor)
Power output: 2,729 hp (2,035 kW)
Specific power: 1.77 hp/cu.in (78.2 kW/L)
Compression ratio: 7:1
Fuel consumption: 85.4 gal/hr (388.2 L/hr) at 2,500 rpm
Specific fuel consumption: 0.55 pints/hp/hr at 1,800 rpm (with exhaust turbine)
Power-to-weight ratio: 1.43 hp/lb (2.36 kW/kg)

Rolls-Royce Condor

Condor I

When it first appeared, in August 1918, the Condor followed very closely the pattern of the Falcon and Eagle, though it was of larger (35 litres) capacity. The Condor Series I was designed for 550/600 h.p., and the larger cylinders necessitated four valves per cylinder instead of two. The valves on each bank were operated by a single camshaft. There were only two carburettors and these were mounted low down on each side of the crankcase in line with the centre bearing. The water pump was transferred to the centre of the engine and an electric starter could be provided.

In succession to the Series I came the IA, wherein the normal output was raised to 650 h.p. at 1,900 r.p.m. There is no record of the Condor II but the Series III, which differed considerably from its predecessors, developed 650 h.p. at 1,900 r.p.m., though it weighed nearly 300 lb less. The Series III was fitted with a single-spur reduction gear, carried in a housing bolted to the front end of the crankcase. This changed the outline of the engine and made for improved cowling lines. The makers nevertheless recognized that higher stresses were set up in the crankcase than with the old epicyclic type. In the new gear a flange was formed on the front end of the camshaft and to this was bolted an internally toothed ring, the teeth of which engaged with similar teeth on the end of a short hollow shaft. The opposite end of the shaft was formed with splines to transmit the torque to a hollow pinion mounted in roller bearings. Thus, any transverse loads were prevented from being transmitted to the crankshaft from the gearing. The pinion engaged with a toothed wheel mounted on, and keyed to, the airscrew shaft, which was supported on roller bearings and was fitted with a ball-and-thrust bearing to take the thrust of the airscrew. The engine was cleared to use a metal airscrew and an efficient diameter was about 16ft.

Another point of difference between the Condor and the earlier Rolls-Royce engines was in the design of the connecting rod assembly: in the former engines articulated rods had been used, the Condor had forked rods.

Condor III

Engines of the Condor III series varied from one another in certain respects, but an Air Ministry description in a publication of 1926 remarks that the various pumps serving the engine had been built into a single unit bolted beneath the crankcase lower half. This unit comprised three oil pumps, a water pump and a petrol pump, the last-named being a unit not previously fitted to any Rolls-Royce engine as a standard component. The description went on: “the carburettor has been redesigned and the altitude control valve is of an entirely new design. Owing to the desire to reduce weight, no hand starting device has been provided, but provision has been made for starting by means of the Bristol gas starter. To this end a gas distributor is provided and is driven from the mechanism contained in the wheelcase.”

The Condor IV was a direct-drive engine intended for fighters, and was extensively flown in the Hawker Hornbill, the fastest fighter of its day. The absence of the reduction gearing saved about 80 lb in weight. Normal output was 650 h.p. at 1,900 r.p.m., and dry weight 1,250 lb.

An experimental Condor was fitted with a turbo supercharger running at 26,000 r.p.m., and giving an induction pipe pressure of 13.5 lb/sq in at a height of 2,000 ft. It was never flight tested. The Series VIII, specially designed for internal installation in a projected Supermarine flying-boat, was another development which was not air-tested.

During 1932 it was announced that a compression-ignition version of the Condor had passed the Air Ministry’s civil-engine type test of 50 hr and that flight trials were then under way at Farnborough in a Hawker Horsley. The C.I. Condor gave 500 h.p. and weighed, with spares and accessories, 1,504 lb. Conversion was initiated by the Air Ministry and the engine was developed at the Royal Aircraft Establishment with the co-operation of Rolls-Royce, Ltd.

British aircraft powered with the Condor included the Beardmore Inflexible, Avro Aldershot, Ava and Andover, Blackburn Iris I. II and III, D.H. Derby, Fairey Atalanta, Titania and Fremantle, Handley Page Handcross, Hawker Horsley, SaundersRoe Valkyrie, Short Cromarty and Singapore, Vickers Vixen and Vanguard, and Westland Yeovil.

A total of 327 engines were recorded as being built.

In 1932 the Air Ministry initiated a conversion of the Condor petrol engine to the compression ignition system. The conversion was developed at the Royal Aircraft Establishment, Farnborough, with the co-operation of Rolls-Royce Ltd. Engine layout, bore, and stroke remained the same as for the petrol version; the compression ratio increased to 12.5:1. The more robust construction required to withstand the increased stresses increased the engine weight to 1,504 lbs (682 kg). At its maximum 2,000 rpm the engine developed 500 hp (373 Kw), giving a power/weight ratio of 0.33 hp/lb.
The engine passed the 50-hour civil type test for compression ignition engines, being only the second British engine to do so. The only previous engine to pass this test was the much larger Beardmore Tornado fitted to the R101 airship. The diesel Condor was experimentally flown in a Hawker Horsley to explore the practical operation of a diesel engine in flight.

Variants:
Condor I
(1920-1921) 600 hp, 72 built at Derby.

Condor IA
Alternative designation for Condor II.

Condor II
(1921) 650 hp, revised propeller reduction gear ratio, increased compression ratio (5.17:1). 34 built at Derby.

Condor III
(1923-1927) 650/670 hp, compression ratio 6.5:1, Re-designed connecting rods. 196 built at Derby.

Condor IIIA
(1925) 650/665 hp. Improved main bearing design and material.

Condor IIIB
(1930) 650 hp, 0.477:1 reduction gear, re-designed crankcase and crankshaft.

Condor IV
(1925) 750 hp. Direct-drive, modified engine mounting. 13 built at Derby.

Condor IVA
(1927) 750 hp. Nine built at Derby.

Condor V
(1925) As Condor IIIA with two-stage turbocharger. Run but not flown, one built at Derby.

Condor VII
Direct-drive Condor IIIA, two built at Derby.

Condor C.I.
(1932) 480 hp, compression ignition (diesel), two engines tested and flown.

Applications:
Avro Aldershot
Avro Andover
Avro Ava
Beardmore Inflexible
Blackburn Iris
Bristol Berkeley
de Havilland DH.27 Derby
de Havilland DH.54 Highclere
de Havilland DH.14 Okapi
Fairey Fremantle
Fairey N.4
Handley Page Handcross
Hawker Hornbill
Hawker Horsley
R100
Rohrbach Ro V Rocco
Saunders Valkyrie
Short Singapore
Vickers Valentia
Vickers Vanguard
Vickers Vixen
Vickers Virginia
Westland Yeovil

Specifications:
Condor III
Type: 12-cylinder liquid-cooled 60 deg. Vee aircraft piston engine
Bore: 5.5 in (139.7 mm)
Stroke: 7.5 in (190.5 mm)
Displacement: 2,137.5 in³ (35.03 L)
Length: 69.3 in (1,760 mm)
Width: 41.1 in (1,044 mm)
Height: 43.2 in (1,097 mm)
Dry weight: 1,380 lb (628 kg)
Valvetrain: Overhead camshaft
Fuel system: 2 x Claudel-Hobson carburettors
Fuel type: Petrol
Cooling system: Liquid-cooled
Power output: 670 bhp (500 kW) at 1,900 rpm
Compression ratio: 5.1:1

Rolls-Royce Buzzard / H Srs

The Rolls-Royce Buzzard (also referred to as the H engine) was a British piston aero engine of 36.7 litres (2,240 cubic inch) capacity that produced about 800 horsepower (600 kW). The Buzzard was developed by scaling-up the Kestrel engine in the ratio of 5:6. Designed and built by Rolls-Royce Limited it featured 12 cylinders in a ‘V’ configuration of 6 inch bore and 6.6 inch stroke, and the engine was supplied as standard with a medium supercharger capable of being used to its fullest extent on the ground, so as to give the maximum possible take-off power, first run in June 1928.

The Series I, II and III engines had reduction gear ratios of 0.632, 0.553 and 0.477 respectively, and the normal power was 825 h.p. at 2,000 r.p.m. at sea level. At 2,300 r.p.m., 955 h.p. was available at sea level. The dry weight was 1,540 lb.

Buzzards were installed in the Blackburn Iris V and VI (Perth), MA/30 and MA/30A, Handley Page H.P.46 (MA/30), Hawker Horsley, Short Singapore I, K.F.I and Sarafand, and Vickers M.1/30.

The total production of Buzzard engines 100.

It was manufactured in the late 1920s, but only 100 were sold. A further development was the Rolls-Royce R Schneider Trophy engine.

Variants:
Buzzard IMS, (H.XIMS)
(1927), Maximum power 955 hp (712 kW), nine engines produced at Derby.

Buzzard IIMS, (H.XIIMS)
(1932-33), Maximum power 955 hp (712 kW), reduced propeller drive ratio (0.553:1), 69 engines produced at Derby.

Buzzard IIIMS, (H.XIVMS)
(1931-33), Maximum power 937 hp (699 kW), further reduced propeller drive ratio (0.477:1), 22 engines produced at Derby.

Applications:
Blackburn Iris
Blackburn M.1/30
Blackburn Perth
Handley Page H.P.46
Hawker Horsley
Kawanishi H3K
Short Sarafand
Vickers Type 207

Specifications:
Buzzard IMS
Type: 12-cylinder liquid-cooled Vee aircraft piston engine
Bore: 6 in (152.4 mm)
Stroke: 6.6 in (167.6 mm)
Displacement: 2,239.3 in³ (36.7 L)
Length: 75.7 in (1,923 mm)
Width: 30.6 in (777 mm)
Height: 44.4 in (1,128 mm)
Dry weight: 1,140 lb (517 kg)
Valvetrain: Overhead camshaft
Supercharger: Single-stage supercharger
Fuel type: 73-77 octane petrol
Cooling system: Liquid-cooled
Power output: 800 hp (600 kW)
Specific power: 0.36 hp/in³ (16.3 kW/L)
Compression ratio: 5.5:1
Power-to-weight ratio: 0.7 hp/lb

Rollason Beta

Rollason / Luton Beta B2

In 1964 Rollasons and the Tiger Club sponsored a competition for a midget racing aircraft which could be used for Formula One air racing. The winner was the Luton Group’s Beta, and after the prototype was attempted by that group, the design was taken over by Rollasons.

Beta B2A G-AWHV Continental C90

The Beta is a single seat sporting monoplane of all wood construction. The wing employs an NACA23012 aerofoil section and consists of a rectangular centre section and tapered outer panels. The wing is made up of a single main spar and auxiliary rear spar, wood ribs and plywood covering. The mass balanced wooden ailerons are fabric covered. Flaps are optional. The fuselage is a semi-monocoque structure consisting of elliptical wooden frames and plywood covered. The cantilever tail unit has a ply-covered fin and tail plane and fabric covered control surfaces. The fixed undercarriage has rubber in compression shock absorbers on early models, but spring steel legs on later models. Fuel capacity is 10.5 Imperial gallons. Four versions of the Beta are available, the basic difference being the engine fitted.

Beta B4 G-AWHW at Sywell 1975. Continental O-200-A

Beta B1
Engine: Continental A65, 65 hp
Wing span: 20.05 ft
Length: 16.08 ft

Beta B2
Engine: Continental C-90, 90 hp

Beta B2A
Engine: Continental C-90, 90 hp
Undercarriage: spring steel

Beta B3
Engine: Ardem 4C02 Mk.V, 55 hp

Beta B4
Engine: Rolls-Royce 0-200-A, 100 hp
Span: 20’ 5”
Length: l6’8”
Wing Area: 66 sq. ft
Empty Weight: 575 lb
Loaded Weight: 866 lb
Max. Speed: 200 mph
Cruise Speed: 166 mph
Stall Speed: 60 mph (less flaps)
Initial Climb: 1,800 fpm
Range: 300 miles