Praga E.114
Encyclopedia
The Praga E.114 was a single-engine sport airplane, designed and manufactured by the Czechoslovakia
Czechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...
n company ČKD-Praga
CKD-Praga
ČKD-Praga was a Czechoslovakian aircraft manufacturer. The company was founded in 1915 as an engine manufacturing company, under the designation Praga. The company started designing aircraft in 1930–31 when the designers Pavel Beneš and Miroslav Hajn came to ČKD-Praga from Avia. Their first...
. Due to its light weight it was also called Air Baby.
Design and development
The Praga E.114, first flown in 1934 and designed by Jaroslav Šlechta, was a high wing, cantileverCantilever
A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...
monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...
seating two in a side-by-side cabin. It was an all wood aircraft with a two spar
Spar
In sailing, a spar is a pole of wood, metal or lightweight materials such as carbon fiber used on a sailing vessel. Spars of all types In sailing, a spar is a pole of wood, metal or lightweight materials such as carbon fiber used on a sailing vessel. Spars of all types In sailing, a spar is a...
single piece wing; the spars and ribs were built from pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
and plywood
Plywood
Plywood is a type of manufactured timber made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured...
and the wing plywood covered. The wing section was reflexed at the trailing edge
Trailing edge
The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge rejoins. Essential control surfaces are attached here to redirect the air flow and exert a controlling force by changing its momentum...
. The wing had a constant chord centre section with taper on the trailing edge outboard and rounded tips. The aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
s were plywood covered and unbalanced
Balanced rudder
The balanced rudder was an innovation in warship construction used as early as 1862 in the USS Monitor, one of the Union's first ironclads during the American Civil War...
.
Its fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
was a pine framed, plywood covered hexagonal box, with the straight edged fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...
an integral part. The rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
was rounded and horn balanced
Balanced rudder
The balanced rudder was an innovation in warship construction used as early as 1862 in the USS Monitor, one of the Union's first ironclads during the American Civil War...
. Though the rudder was wood framed and covered, the tailplane, mounted just above the fuselage and externally braced from below, had a tube steel structure and was fabric covered
Aircraft fabric covering
Aircraft fabric covering is a term used for both the material used and the process of covering aircraft open structures. It is also used for reinforcing closed plywood structures, the de Havilland Mosquito being an example of this technique....
. The elevators
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...
were balanced by an elastic rope
Bungee cord
A bungee cord , also known as a shock cord, is an elastic cord composed of one or more elastic strands forming a core, usually covered in a woven cotton or polypropylene sheath...
to the control column.
Early in the design process the E.114 had been envisaged as an open cockpit aircraft but by the time of construction there was an enclosed cabin. The first prototype had rather crude glazing constructed from plane panes. The absence of doors made entry somewhat challenging, with the side panels hinged down and the upper pane, together with part of the wing leading edge
Leading edge
The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one....
hinged upwards. The second prototype added a lower fuselage foothold to ease the process, as well as fitting less angular glazing. The undercarriage
Undercarriage
The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...
, which was also used as a first step into the cabin, was of the divided type with faired legs hinged on the lower fuselage, assisted by struts from the centre line to the wheels. The wheels contained rubber shock absorbers and were optionally spatted
Early aircraft were powered by a 29 kW (36 hp) Aeronca air-cooled flat four engine mounted in the extreme nose with its cylinders exposed. Early production aircraft replaced the US-built Aeronca with a Czechoslovakia
Czechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...
n version of it, also built by Praga, called the Praga B. Later the similar but more powerful Parga B-2 was fitted and from 1936 this was replaced in turn by the Praga D
Praga D
The Praga D was a four-cylinder, air-cooled, horizontally opposed aircraft engine first produced in Czechoslovakia in 1936 but which enjoyed its greatest success after World War II due to the explosion in popularity of sports flying.-Specifications :...
. This was another flat four, producing 49/55 kW (65/74 hp), with each pair of exposed cylinders merged into a single housing for lower drag. Aircraft with this engine were referred to as E.114D.
As well as benefiting from more power, the E.114D had other enhancements. The ailerons were balanced, improving the stall characteristics; the vertical surfaces were increased in area and given a more angular profile with a non-balanced rudder.
The last E.114 variant involving an engine change was the E.114M, fitted with a 49 kW (65 hp) Walter Mikron III
Walter Mikron
|-See also:-References:* Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9-External links:*...
four-cylinder inverted inline engine. The full cowling changed the look of the nose considerably and increased the length by 510 mm (20 in). The E.114M was the heaviest of the series, with an empty weight of 415 kg (915 lb); the E.114D weighed 330 kg (728 lb). The wing carried noticeable dihedral and the E.114M was the only one of its type to have a tailwheel rather than a skid. It was the fastest of the type, with a maximum speed of 185 km/h (115 mph).
The E.115 appeared in 1937 with significant changes to the wing. The span was only slightly reduced (by 200 mm or 7.9 in) but continuous taper reduced the area by 20%. The ailerons were fabric covered. It could be powered by either the Praga B or D and was noticeably faster than earlier variants, even with the smaller engine. The E.115 also had a revised undercarriage, with single, streamlined steel struts hinged to the lower fuselage braced by rods to the centre section. The wheels were spatted and the legs sprung with bungee cord
Bungee cord
A bungee cord , also known as a shock cord, is an elastic cord composed of one or more elastic strands forming a core, usually covered in a woven cotton or polypropylene sheath...
inside the fuselage.
The E.117 of 1937 had major alterations. The wing was the same span as that of the E.114 but was given a straight taper, resulting in a small (3.3%) decrease in area. For the first time flaps (of the split type) were fitted. The wing remained wooden but a steel framed, fabric covered fuselage was used and the fin and elevator were similarly constructed. The new fuselage construction allowed the E.117 to have cabin doors for the first time, as well as a more generous interior. It had cantilever undercarriage legs, with wheels in fairings and a tailwheel in place of the skid used by most of the E.114s and E.115, though one of the only two E.117s built flew for a time with a tricycle undercarriage, its mainlegs moved rearwards and with a faired nosewheel assembly.
The E.214, which appeared in about 1936 or 1937 was essentially an E.114 with a 56 kW (75 hp) Pobjoy R
Pobjoy R
|-See also:-Bibliography:* Guttery, T.E. The Shuttleworth Collection. London: Wm. Carling & Co, 1969. SBN 901319-01-5* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
seven-cylinder radial engine
Radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders point outward from a central crankshaft like the spokes on a wheel...
. The structure was the same as that of the E.114 and the wings had the same dimensions. With a length of 7.15 m (23 ft 5½ in), the E.210 was a few millimetres longer than the E.114M, despite the latter's much longer engine and the extension provided space for a second pair of seats behind the first, making the E.210 a four-seater. The new seats were accessed via a side door, though the front pair retained the side window route of the earlier aircraft. A trim tab on the elevator replaced the elastic rope balance and the undercarriage was also new, each side having an oleo
Oleo
Oleo is a term for oils. It is commonly used to refer to a variety of things:* Margarine* Oleic acid* Oleo , A type of shock absorbers on airplane landing gear* Oleo , a bebop composition by Sonny Rollins...
leg fixed to the lower fuselage longeron
Longeron
In aircraft construction, a longeron or stringer or stiffener is a thin strip of wood, metal or carbon fiber, to which the skin of the aircraft is fastened. In the fuselage, longerons are attached to formers and run the longitudinal direction of the aircraft...
and braced at its lower end by a V-form strut, hinged on the fuselage centreline. At 420 kg (926 lb), its empty weight was close to that of the E.114M. Maximum speed was 170 km/h (106 mph).
Operational history
The first Air Baby prototype flew for the first time in September 1934 and appeared at the Czech National Flying Club Competition. After several demonstration flights within EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
it was displayed at the 1934 Paris salon.
The Praga was produced before World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
both both by ČKD-Praga
CKD-Praga
ČKD-Praga was a Czechoslovakian aircraft manufacturer. The company was founded in 1915 as an engine manufacturing company, under the designation Praga. The company started designing aircraft in 1930–31 when the designers Pavel Beneš and Miroslav Hajn came to ČKD-Praga from Avia. Their first...
in Prague
Prague
Prague is the capital and largest city of the Czech Republic. Situated in the north-west of the country on the Vltava river, the city is home to about 1.3 million people, while its metropolitan area is estimated to have a population of over 2.3 million...
and, under licence as the Hillson Praga, by F. Hillson & Sons Ltd of Manchester
Manchester
Manchester is a city and metropolitan borough in Greater Manchester, England. According to the Office for National Statistics, the 2010 mid-year population estimate for Manchester was 498,800. Manchester lies within one of the UK's largest metropolitan areas, the metropolitan county of Greater...
in the UK. The numbers of E.114s produced in Czechoslovakia in this period and into the war are uncertain because of probable gaps in the constructor's number (c/n) run. 156 is the probable maximum number built, but the size of the gaps is not known. Hillsons built 28 Pragas. After the war production resumed at ČKD until 1948, when about 110 E.114D and E.114M had been made. Another 26 E.114Ms were built by the Rudy Letov Co. in Czechoslovakia. Including the various non-E.114 variants, these figures suggest a maximum production of 324.
In 1938 the E.115, then powered by a Praga B engine, set a class speed record at 171.5 km/h (106.6 mph) over a 100 km (62 mi) course. In May 1936 one was flown from the UK to South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
in a new record time of 16 days and 4.5 hours. No South African sales followed and this aircraft was later converted into a glider.
Two E.114s participated in the Sternflug to the 1936 Summer Olympics
1936 Summer Olympics
The 1936 Summer Olympics, officially known as the Games of the XI Olympiad, was an international multi-sport event which was held in 1936 in Berlin, Germany. Berlin won the bid to host the Games over Barcelona, Spain on April 26, 1931, at the 29th IOC Session in Barcelona...
in Berlin. The two E.114 pilots, Fuksa and Polma, took the first two places ahead of competitors, equipped with aircraft with more powerful engines.
Before the war some Czech built E.114s were exported to other European countries including Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
and Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
. The first Hillson Praga was exported to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. Demand for the type in the UK was subdued and over half went to flying clubs, including a batch of ten to the Northern Aviation School & Club (NAS&C), set up at Barton Aerodrome
Barton Aerodrome
City Airport is a general aviation airport in the Barton-upon-Irwell area of Eccles, in the City of Salford, Greater Manchester, England. Formerly known as both Barton Aerodrome and City Airport Manchester...
near Manchester by the manufacturers for this purpose. The NAS&C also trained prospective pilots of the Civil Air Guard
Civil Air Guard
The Civil Air Guard was a 1938 scheme in which the UK government subsidized training fees for members of flying clubs, in return for future military call-up commitments.-History:...
. The Praga B engines manufactured in the UK by Jowett Cars Ltd proved unreliable and at least five were replaced by the much heavier 30 kW (40 hp) Aeronca JAP J-99 flat twin. A Hillson Praga won the Manx Air Derby, flying three circuits of the Isle of Man
Isle of Man
The Isle of Man , otherwise known simply as Mann , is a self-governing British Crown Dependency, located in the Irish Sea between the islands of Great Britain and Ireland, within the British Isles. The head of state is Queen Elizabeth II, who holds the title of Lord of Mann. The Lord of Mann is...
on 1 June 1936 at 144 km/h (89.5 mph).
Post-war Czech built E.114Ms were exported to France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, Italy, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
, Romania and the Saarland
Saarland
Saarland is one of the sixteen states of Germany. The capital is Saarbrücken. It has an area of 2570 km² and 1,045,000 inhabitants. In both area and population, it is the smallest state in Germany other than the city-states...
. Used as tourers and trainers, they also acted as glider tugs. Five Hillsons survived the war but only two flew again. One crashed in Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
in 1946 and the other in Italy in 1957.
In 2000 there were two surviving E.114s, both in Switzerland. One of these had a 67 kW (90 hp) Continental C90-12F engine. The 2010 Swiss register shows only HB-UAF, an E.114M, but it is not known if it is still active.
Variants
All variants apart from the E.115 had the same dimensions. Data from Air Britain Archive No.3 (2011), p.129E.114 (Praga B)
- 30 kW (40 hp) Praga B flat four engine.
E.114 (Praga B-2)
- 36 kW (45 hp) Praga B-2Praga B2|-See also:...
flat four engine. As specifications.
E.114 (Praga D) or E.114D
- 49-59 kW (65-79 hp) Praga DPraga DThe Praga D was a four-cylinder, air-cooled, horizontally opposed aircraft engine first produced in Czechoslovakia in 1936 but which enjoyed its greatest success after World War II due to the explosion in popularity of sports flying.-Specifications :...
flat four engine. Maximum speed 150 km/h (93 mph).
E.114M
- Marked dihedral on wing. 48 kW (65 hp) Walter Mikron III four-cylinder inline engine. Maximum speed 185 km/h.
E.114C
- At least one E.114M was modified to accept a 49 kW (65 hp) Continental flat four sometime after 1952 and this was registered as an E.114C.
E.115
- Span decreased to 10.8 m (35 ft 5 in), wing area to 12.15 m² (130.78 ft2); length increased to 6.8 m (22 ft 4 in). 36 kW (45 hp) Praga B-2 flat four engine. Maximum speed of 173 km/h (108 mph). Only one built.
E.117
- Changes to wing and fuselage. Flaps added. Wing area 14.75 m² (158.77 ft2). 49-59 kW (65-79 hp) Praga D flat four engine. The fastest Praga engined Air Baby, with a maximum speed of 216 km/h (134 mph). Only two built. One flew for a while with a tricycle undercarriage.
E.214
- E.114 variant with a 56 kW (75 hp) Pobjoy RPobjoy R|-See also:-Bibliography:* Guttery, T.E. The Shuttleworth Collection. London: Wm. Carling & Co, 1969. SBN 901319-01-5* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6....
seven-cylinder radial engine, lengthened fuselage and seating for four.