Designed by František Adolf Barvitius in 1934, the Walter Atom was an air-cooled horizontal (flat) two-cylinder engine used on light aircraft and gliders.
It was the smallest engine in the Walter air-cooled range built between the world wars, and was markedly atypical in that it was a flat, horizontal engine. It was originally intended as a suitable power unit for motorized gliders. It is also interesting that on the “eve” of World War II, amateur pilots in Aeroclubs began to use motorized gliders. Pavel Beneš counted on it for the first such glider (Be-500 “Bibi”) from the Beneš-Mráz aircraft factory in Choceň, Pavel Beneš – Jaroslav Mráz. However, this plan was not implemented, but the design preparation of the type Beneš-Mráz Be-500 Bibi was used in the construction of subsequent types Be-501 and Be-502. However, they used more powerful Walter Mikron and Walter Minor 4 engines.
The two-piece motor housing was cast from Hiduminium and was closed on both sides with electron lids. Ribbed aluminum alloy heads with bronze seats and valve guides were mounted on the ribbed steel cylinders. The cylinder heads were removable and were attached to the housing along with the cylinders by four through bolts. The head and the cylinder itself were surface protected by galvanic cadmium plating.
The steel crankshaft was made of machined forging and was housed in a housing in two bronze plain bearings, which were cast with bearing metal, and in one pressure ball bearing, which absorbed the axial forces from the propeller. The propeller head was mounted on the tapered end of the crankshaft and was secured with a wedge and nut. The H-section connecting rods were forged from aluminum and the pistons were cast. The pistons had two sealing rings and one wiper ring. The lubrication was a pressure circulating (wheel pump) with an oil tank at the bottom of the engine case.
There was one Amal carburetor with a corrector on each cylinder. The ignition was double, Bosch-type magnets that were mounted on the rear bonnet.
The Walter Atom engine was created in 1934, went into small-scale production in 1935 and reached a maximum take-off power of 20 kW (28 hp), which in turn was not so small for a two-cylinder with a capacity of 1.1 liters. The arrangement of the engine with the cylinders facing each other was chosen so that the operation of the engine did not strain the construction of the machine (aircraft, glider).
The Atom was manufactured by Walter Joint-Stock Company, a car and aircraft engine factory, since 1935.
In April 1936, the MLL sail department at Walter built the ŠP2 glider, on which the two-cylinder Atom was to be mounted. However, the main application was the conversion of the classic glider EL-2-M “Gray Wolf” to a motorized version. The designation was created as standard: EL are the initials of the designer (Elsnic Ludvík) and 2-M means two-digit. According to other sources, the “M” in the designation referred to the possibility of mounting the engine on a glider.
The first motorized Gray Wolf (EL-2-M) was a glider built by the sailing department of the Masaryk Aviation League (MLL) in Moravian Ostrava. The new Walter Atom engine from 1935 was used here for the first time. The engine was on a tubular pyramid above the canopy of a wing with a propeller. It was mainly used as a two-seater for training students of gliding who have already passed the “B” exam.
Enthusiasts from the active branch of the Masaryk Aviation League (MLL) in Humpolec are behind the most well-known application on a motorized glider. At the beginning of 1937, they built a motorized, single-seater glider, which was actually a slightly redesigned school two-seater glider EL-2-M Gray Wolf with an auxiliary engine Walter Atom. The designer of the Gray Wolf, Ludvík Elsnic, the chief pilot of the MLL, flew and tested this modified glider on April 11, 1937.
Walter Atom and the motorized glider Humpolec EL-2-M Gray Wolf (Early 1938)
The numbers of engines produced 1935-1939 are not reported in official sources, apparently only as units.
After the Second World War, a similar, small engine, in-line two-cylinder Walter A (type designation M-100) designed by Bohuslav Šimůnek (1946) was created in the Walter factory. It had a rated power of 16 kW / 22 hp at 2,500 rpm and was also designed to power motorized gliders.
In the National Technical Museum, a preserved Walter Atom engine is on display in the transport hall.
Atom Type: Horizontal 2 cylinder air-cooled Bore: 85 mm (3.35 in) Stroke: 96 mm (3.78 in) Displacement: 1.09 L (66.5 cu in) Total piston area: 437 cm² Length: 510 mm (20.08 in) Width: 815 mm (32.09 in) Height: 409 mm (16.10 in) Dry weight: 40 kg (88.2 lb) Nominal, rated power: 25 hp (18.4 kW) at 2600 rpm Maximum (take-off) power: 28 hp (20.6 kW) at 3000 rpm Power / volume ratio: 22.7 k / l (16.7 kW / l) Valvetrain: 1 inlet and one exhaust valve per cylinder Lubrication: pressure, circulating Oil consumption: 15–20 g · h − 1 · k − 1 / 20.4-27.2 g · h − 1 · kW − 1 Fuel system: 2 Amal carburettors Fuel type: 68 octane Fuel consumption: 260–270 g · h − 1 · k − 1 / 354–367 g · h − 1 · kW − 1 Cooling system: air Distribution: OHV, one intake and one exhaust valve per cylinder Ignition: 2 Bosch magnets Power output: 21 kW (28 hp) at 3000 RPM Compression ratio: 5.2:1 Power-to-weight ratio: 2.14 kg/kW (3.52 lb/hp) at cruise Power to weight ratio (specific weight): 0.62 k / kg (0.46 kW / kg) Specific performance: 1.6 kg / k (2.14 kg / kW)
Originally the Walter turbo prop was designed for the harsh Russian environment with limited field maintenance. The engine does not require a hot section inspection, and requires only an inspection every 300 hours. First run in 1967, the Walter M601 is a turboprop aircraft engine produced by Walter Aircraft Engines of the Czech Republic. The company’s first turboprop, the M601 is used in business, agricultural and military training aircraft.
The turboprop was designed for use on the Let L-410 and the M601 first ran in 1967. It was not suitable for the prototype L-410 and the company developed an upgraded version, the M601A, with a slightly wider diameter.
Variants: M601A Initial production variant for early version of the Let L410.
M601B Production variant for the Let L410UVP.
M601D Developed for the Let L410UVP.
M601D-1 Agricultural variant for high-cycle operation, used on the PZL Kruk and Ayres Thrush.
M601D-2 Special variant for paradrop aircraft, used on the Do 28 and some Finist conversions.
M601D-11 Agricultural and paradrop variant with a higher Time Between Overhaul of up to 1800 hours.
M601D-11NZ Downrated variant for use in the FU-24 Fletcher.
M601E Developed for the Let L410UVP-E.
M601E-11 General use engine with sub-variants of differing TBO.
M601E-11A Variant of the 11 for use at higher operating altitudes and modified with a low pressure bleed air system for pressurised aircraft.
M601E-21 Variant for the L410-UVP-E used for hot and high operations.
M601F Variant intended for use on the L420-UVP.
M601FS
M601F-11
M601F-22
M601F-32
M601FS
M601T Aerobatic variant for use on the PZL Orlik.
M601H-80 now the GE Aviation Czech H80
M601Z Agricultural variant for use on the Z-37T.
Applications: Aerocomp Comp Air 10 XL Aerocomp Comp Air 7 Ayres Thrush Dornier Do 28 Lancair Propjet Let Z-37T – TurboČmelák (AgroTurbo) Let L-410 Turbolet Let L-420 Myasishchev/SOKOL M-101T PAC FU-24 Fletcher Progress Rysachok PZL-106 Kruk PZL-130 Orlik
Specifications: Take off rating: 690 shp / 515 kW Prop speed: 2080 rpm Interturbine temp: 710 deg C Max continuous: 606 shp / 452 kW Gas generator speed: 36,080 rpm Prop speed: 1800-2000 rpm Interturbine temp: 690 deg C Max reversing rating: 413 shp / 308 kW Weight: 420 lb / 190.5 kg
M601D-1 Type: Turboprop Length: 1675 mm Diameter: 590 mm Dry weight: 197 kg Compressor: 2-stage axial compressor and 1-stage centrifugal compressor Combustors: annular Turbine: 1-stage high-pressure and 1-stage free Maximum power output: 544 kW, 490 kW continuous (740 hp, 657 hp continuous) Turbine inlet temperature: 690°C Specific fuel consumption: 0.62 lbs/shph Power-to-weight ratio: 2.76:1 (kW:kg)
The Walsh Seaplane itself lasted only 15 months before being dismantled and parts from it were used in the building of an improved flying boat known as “The Roberts”.
The business syndicate, displeased with Vivian’s seemingly excessive caution, took possession of the Manurewa; soon after, it crashed and was damaged beyond repair. Recovering from this setback, Leo, with Vivian’s help, began to design a flying boat of the American Curtiss type which he thought would suit New Zealand conditions. The brothers gained the financial and practical assistance of R. A. Dexter, an American engineer and motor dealer in Auckland, who was to be a consistent supporter.
Fifteen months’ spare time work went into the construction of this aircraft; all the work was carried out by the Walsh brothers, Leo and Vivian, with the exception of the steel fittings which were manufactured by Mr R.A. Dexter, an Auckland engineer who was backing the project.
The hull planking was cedar with ash stringers and mahogany ribs; the hull weighed 305 lbs. Aluminium decking was provided on the forward portion of the hull and the after portion was covered with a special cloth stretched over cedar battens. Seven watertight compartments were built into the hull. The two mainplanes (each 41 ft 6 ins long) had front and rear spars of ash with cedar rib. The fabric covering the wings and the tailplane was doped with cellulose. The aircraft was powered by a 10-cylinder 4-stroke Anzani engine fitted in a special housing at the rear end of the top mainplane. An 8 ft laminated walnut and mahogany propellor with brass tips was fitted.
The aircraft was constructed at the Walshs’ home in Remuera and when completed was dismantled and carried to Bastion Pt, Orakei. After re-assembly the aircraft was launched on January 1, 1915. After taxiing trials and final adjustments, Vivian Walsh took off in the flying boat for a short test flight around Bastion Pt. Many practice flights followed and on March 14 carried its first passengers (covering a distance of five miles). Even with the light weight of this aircraft (1,200 lbs) the 80 hp Anzani radial engine was only just sufficient to keep the aircraft flying and many hours of work by Leo Walsh were required to keep the engine tuned.
In March 1915 Vivian took the first of many passengers on a flight of five miles. The flying boat itself lasted only 15 months before being dismantled and parts from it were used in the building of an im¬proved flying boat known as “The Roberts”.
Leo and Vivian Walsh helped to lay the foundations for both military and civil aviation in New Zealand. Leo (Austin Leonard) Walsh was born on 5 February 1881 at Bradford, Yorkshire, England, the eldest child of Jane Mary Towler and her husband, James Austin Walsh, a tobacco manufacturer. Leo’s sister Veronica Agnes was born in 1883 and soon afterwards the family emigrated to Auckland, New Zealand. There Vivian Claude was born on 6 November 1887, and Doreen Monica in 1895. Their mother died in 1904.
Both Leo and Vivian showed an early interest in engineering and, encouraged by their father, Austin Walsh, they established a mechanical engineering and motor importing business in Auckland. Fascinated by accounts of aviation experiments in Europe and America, with other enthusiasts they formed the Aero Club of New Zealand in 1910. The brothers were determined to build and fly an aeroplane and succeeded in obtaining financial backing from Auckland businessmen A. N. and C. B. Lester and A. J. Powley. They then bought the plans for a British Howard Wright biplane together with materials and an eight-cylinder engine, worth about £750 in total. It took about 5½ months for the brothers to assemble the aircraft at their family home in Remuera. They were helped by fellow enthusiasts, and their sisters Veronica and Doreen, who machine-sewed hundreds of yards of material for the wings. The finished aircraft, named the Manurewa No 1, bore an inscription ‘The Walsh Aeroplane Co. Aeronautical Engineers Constructors Auckland’. Beneath this was a crest and the words ‘Aero Club New Zealand’.
Walsh Brothers aircraft Manurewa
The Manurewa was dismantled and transported to Glenora Park, a private racecourse at Papakura, where it was reassembled for flight. Vivian was the first to fly the plane, and, being careful, made several taxiing tests on the ground before his first successful flight of about 400 yards at a height of 60 feet in early February 1911. The flight was witnessed by a small group of local residents, Aero Club members and a proud family, and was to be followed by many more. Vivian kept detailed records and gradually built up knowledge of the controls and performance of the aircraft. Leo did not attempt to fly the plane as he feared his reactions were too slow, but he was a skilled designer and organiser. The brothers’ different talents made them a formidable team.
The business syndicate, displeased with Vivian’s seemingly excessive caution, took possession of the Manurewa; soon after, it crashed and was damaged beyond repair. Recovering from this setback, Leo, with Vivian’s help, began to design a flying boat of the American Curtiss type which he thought would suit New Zealand conditions. The brothers gained the financial and practical assistance of R. A. Dexter, an American engineer and motor dealer in Auckland, who was to be a consistent supporter. After more than a year in construction the new aircraft was completed in November 1914 and transported to Bastion Point on the Waitemata Harbour. Here Vivian took it for its first flight on 1 January 1915. It was the first flying boat designed and built in the southern hemisphere and proved a great success. In March 1915 Vivian took the first of many passengers on a flight of five miles.
With the outbreak of the First World War the military use of aircraft was soon recognised, and many would-be pilots in New Zealand wrote to the Defence Department asking how they could qualify to join the Royal Flying Corps. The Walsh brothers also received letters of enquiry and were eager to set up a training school. With some difficulty they persuaded the New Zealand government to back the idea and approach the British authorities. The response was very encouraging: the RFC asked for as many candidates as could be trained and agreed to issue an aviator’s certificate by cable to each trained pilot, provided the qualifying flight was witnessed by official military observers.
The New Zealand Flying School was formed by the Walsh brothers and began training pupils in October 1915. Headquarters were established first at Orakei, and in November on the foreshore at Mission Bay. Leo Walsh was managing director, Vivian Walsh was chief pilot and superintendent, R. A. Dexter was director and Austin Walsh was secretary. Both Doreen and Veronica Walsh were involved in the practical running of the school. As well as providing flying instruction, the school built and maintained aircraft, so various other staff including engineers and mechanics were taken on. Some ex-pupils later became flying instructors.
In February 1916 the school gained Imperial recognition which brought with it the official involvement of the New Zealand Defence Department, and elements of military training were incorporated into the school’s programme. The first pilot’s certificate was issued to Vivian Walsh on 13 July 1916. The school obtained its second aircraft in November 1915 and other planes, including the first two Boeing float planes constructed, were acquired later. Over 100 pilots were trained during the war; most saw combat and many gained honours and decorations. The most famous was Keith Logan Caldwell, one of the original three pupils. Vivian, who had set high standards for training, was forced to give up flying in 1919 because of ill health and instead helped Leo to manage the school.
At the end of the war it seemed that the New Zealand Flying School might no longer be needed, but the Bettington Report (1919) on aviation recommended that this and the Canterbury (NZ) Aviation Company’s flying school be maintained. In 1920 the government voted £25,000 to keep the schools in existence, but only a small proportion of this was advanced to the New Zealand Flying School. Nevertheless, it served to keep the hopes of the Walsh brothers alive.
Meanwhile, they became involved in other projects. In late 1917 Vivian had given demonstration flights at Napier showing the potential use of aircraft for passenger and mail services. In 1919 Leo raised with the government the possibility of establishing an airmail system, and on 16 December that year the first official airmail flight in New Zealand took place between Auckland and Dargaville. Other experimental mail flights to Thames, Whangarei and Dargaville were arranged, and a regular service between Auckland and Whangarei was introduced on 9 May 1921. This lasted only a short time as it proved to be uneconomic; regular passenger flights did not start for many years for the same reason. With Arthur Upham as pilot, Leo Walsh carried out survey flights for the Fijian colonial government in July 1921 in an attempt to demonstrate the use of aircraft in communications.
Very soon the financial burden of operating the flying school became onerous. Leo and Vivian Walsh struggled to keep the school in existence by offering pleasure flights and undertaking charter work. By 1923 they had exhausted their resources and asked the government to take over the school. In October 1924 the government bought the assets of the New Zealand Flying School for about £10,500 – insufficient, Leo Walsh noted, to give any return to shareholders in the venture. Bitterly disappointed, Leo and Vivian Walsh gave up all involvement in aviation and returned to their engineering business, which from the late 1920s was located in Hobson Street, Auckland. Vivian died on 3 July 1950 and Leo on 16 July 1951; neither had married. While the brothers received no official recognition during their lives, in 1952 the Auckland Branch of the New Zealand Division of the Royal Aeronautical Society initiated the Walsh Memorial Fund to further the interests of aviation and to perpetuate the names of two aviation pioneers.
In its original configuration (with nose wheel); the modern looking monoplane devised by Charles Francis Walsh, who had founded the San Diego Aeroplane Manufacturing Company the previous year. The machine, with its massive wing, would probably have flown but was severely handicapped by its underpowered Cameron automobile engine of only 29 hp.
