Tatra 77

Tatra 77 Tatra 77a
Overview
Manufacturer	TATRA, a. s.
Production	1934-1935 Tatra 77 1935-1938 Tatra 77A 249 produced[1] (+ 4 pre-serial in 1933) [2]
Assembly	Kopřivnice, Moravia, Czechoslovakia
Designer	Hans Ledwinka Erich Übelacker
Body and chassis
Class	4-door sedan
Body style	limousine (Finned Fastback)
Layout	RR layout
Powertrain
Engine	3.0L Tatra 77 V8 (T77) 3.4L Tatra 77a V8 (T77a)[1]
Transmission	4-speed manual[1]
Dimensions
Wheelbase	3,150 mm (124.0 in)[1]
Length	5,000–5,200 mm (196.9–204.7 in) (T77) 5,300–5,400 mm (208.7–212.6 in) (T77a)[1]
Width	1,650 mm (65.0 in) (T77) 1,660 mm (65.4 in) (T77a)[1]
Height	1,420–1,500 mm (55.9–59.1 in) (T77) 1,600 mm (63.0 in) (T77a)[1]
Curb weight	1,700 kg (3,700 lb) (T77) 1,800 kg (4,000 lb) (T77a)[1]
Chronology
Predecessor	Tatra V570
Successor	Tatra 87

The Czechoslovakian Tatra 77 (T77) is the first serial-produced truly aerodynamically designed automobile. It was developed by Hans Ledwinka and Paul Jaray, the Zeppelin aerodynamic engineer. Launched in 1934, the Tatra 77 is a coach-built automobile constructed on a central tube-steel chassis and is powered by a 75 horsepower (56 kW) rear-mounted 3.4-liter air-cooled V8 engine. It possessed advanced engineering applications such as overhead valves, hemispherical combustion chambers, dry sump, fully independent suspension, rear swing axles and extensive use of lightweight magnesium-alloy for the engine, transmission, suspension and body. The average drag coefficient of a 1:5 model of Tatra 77 was recorded as 0.2455. The later model T77a has a top speed of over 150 km/h (93 mph) due to its advanced aerodynamics design which delivers an exceptionally low drag coefficient of 0.212,^{[3][4][5][6][7]} although some sources claim that this is the coefficient of a 1:5 scale model, not of the car itself.^[8][9]

History

The Tatra Company began manufacturing cars in 1897 in Kopřivnice, Moravia, today's Czech republic, making it the third oldest still existing automobile manufacturer in the world. Under the direction of Hans Ledwinka, the company employed many genius minds of automotive history, including Erich Übelacker and consultant Paul Jaray, who all designed the Tatra 77.^[10]

Paul Jaray and Tatra V570

Paul Jaray first worked at Luftschiffbau Zeppelin (LZ) where he gained experience with aerodynamic design of airships. He used his access to LZ's wind tunnels and subsequently established the streamlining principles for car design. In 1927 he founded a company specializing in developing streamlined car bodies and selling issuing licenses to major vehicle manufacturers. Tatra was the only manufacturer to incorporate Jaray streamline principles into their series car production, starting with the Tatra 77.

Before designing the large luxurious T77, Jaray designed an aerodynamic body for the Tatra 57, a mid-range model. This prototype was not further developed and failed to reach production. Instead, Jaray constructed two prototypes for a concept designated as the Tatra V570, which more closely conformed to his aerodynamic streamlining principles, featuring a beetle-shaped body.

Decision to make luxurious state-of-the-art car

However, at the time Tatra already had a cheap well selling car in its production range, which was moreover popular due to its continuation of simple and ultra-reliable tradition started by model Tatra 11. Although the management saw the advantages of Jaray's concept, they believed that the new model will be only an additional model with limited production, which meant that it should be aimed at the top of automobile market. The Ledwinka's team subsequently stopped work on V570 and concentrated on designing large luxurious cars. Tatra aimed at making state-of-the-art cars that would be fast, stable, nearly silent, economical and built to the most rigorous engineering standards, as well as reflect modern aerodynamic research.^[11]

Public response

Hans Ledwinka was the chief-designer responsible for the development of the new car, while Erich Übelacker was responsible for the body. The development was very secretive until the last moments of the official presentation on May 3, 1934 at Prague motorshow. The car was demonstrated on the road from Prague to Karlovy Vary, where it easily reached 145 kilometres per hour (90 mph) and amazed newspapermen with great handling and comfortable ride at speeds of about 100 kilometres per hour (62 mph). That same year the T77 was presented at the Paris motorshow, where it became the center of attention not only due to its atypism, but also due to its performance. There were even demonstration rides after the ability of the car to reach 140 kilometres per hour (87 mph) with a mere 45 kilowatts (60 hp) of engine power to reach was doubted, as normally at the time for a car to reach such a speed required about twice as much horsepower. Director Maurice Elvey was so amazed by the looks of the car that he used the T77a in his science-fiction movie The Transatlantic Tunnel.^[9][12]

"It is a sensation when it comes to its construction, to its appearance and to its performance. However, it isn't a sensation that would just fall down from the skies, but a logical continuation of the road, which Hans Ledwinka took thirteen years ago. The ideological principle of the new Tatra is an understanding, that the car is moving at the dividing line between the ground and the air. ... The car maintained 145km/h, it has astonishing handling, it drives through the curves with speeds that are both mad and safe, and it seems, that it is only floating on whatever road. ... It is a car, which opens new perspectives to the car construction and automotive practice."
Vilém Heinz, Motor Journal, 1934 ^[13]

"That is the car for my highways!"
Adolf Hitler to Ferdinand Porsche ^[4][10][14] See Volkswagen controversy

Notable owners

The Tatra 77 was the particular favourite of Tatra design engineer Erich Übelacker, who owned and used a T77 himself since 1934. Other famous owners of T77s were Milos Havel, the proprietor of the film studios in Prague who bought a T77 in 1935, Austrian car designer Edmund Rumpler, who designed the aerodynamic Rumpler Tropfenwagen in 1921, Edvard Beneš, the 1930s minister of Foreign Affairs and later president of Czechoslovakia, who both owned a T77a.^[15]

Design

A number of designers around the world were trying to construct an aerodynamic car at the time, but Tatra was the first one to successfully introduce it into serial production. There were numerous reasons why Tatra designers took such a revolutionary approach to the conception of the new car: First of all it was the aim to reduce drag, mostly air-drag, which increases with the square of speed. A car with a common body shape of the era needed a very powerful engine to reach higher speeds. The Tatra's new body shape was wind tunnel tested. However, the new type of coach building required a change of the whole car's concept.

The requirement of a small front face area limited the car's height, which in turn required the use of a flat floor. That led to putting the engine in the rear of the car, directly above the driven axle. Subsequently there was no more need for a floor tunnel with a drive shaft and exhaust pipes, which contributed to weight loss. As the designers wanted to reduce the rolling resistance, they did their best to produce an engine as light as possible – an air-cooled V8 with a crank case made from elektron, a magnesium alloy. The transmission box was made from elektron as well and it was positioned in front of the rear axle and engine.

The rear position of the engine was favourable for the air cooling, while the oil cooler, battery and spare wheel were positioned in the front of the car. The frameless body was characterized by the central frame member, which was firmly welded to the floor panels and which covered the linkage to the brakes, gears, etc.

The front of the car has basically a rectangular cross section and it is rounded at the front to the height of the floor. The front bumper covers the front rounded fenders, while the lower half of the lights is embedded in the front bonnet. The rear of the car has a continuous dropping form, and it is divided by a vertical fin, which starts at the rear end of the roof and ends almost at the rear end of the car. The rear wheels have aerodynamic covers. The door handles are embedded into the door panels, from which only the door hinges stood out, if also not by much. The car had no rear window, and rear visibility was fairly limited, and only possible through slots on the sheet metal.

The first prototype of 1933 had a split windshield, while other prototypes had a one piece windshield or even one formed by three separate pieces of glass, with one large central piece and two side parts angled sharply and flowing into the sides of the body.

The air was directed to the engine by rectangular ventilation inlets behind the side windows and it left the engine compartment through the rear exit vents. At the time, Tatra registered numerous patents regarding the air flow to the rear engine compartment.

Later the rear part of the body was widened so that both the rear fenders and door hinges were embedded into the bodywork itself. The air now flowed through transversal inlets, which raised above the rear rounded roof. The trailing edge was raised.^[16]

Tatra 77a

In 1935 the T77 was updated and improved, which resulted in the T77a. The capacity of the V8 was increased to 3.4 L (207 cubic inches). This accomplishment was achieved by enlarging the bore diameter from 75 to 80 mm (3.0 to 3.1 inches). The new motor increased output to 75 hp (56 kW) and maximum speed to 150 km/h (93 mph). The front now had three headlamps of which the central unit was linked to the steering on some models, making it possible to turn the lamp while steering. Some T77s and T77as were also equipped with canvas Webasto roofs. The smooth body of the T77a gave a coefficient of aerodynamic drag of 0.212, an incredibly low value even for today's cars, as only a few modern prototypes are able to achieve this figure although some sources confirm that this figure is based on a 1:5 model test.^[8][9]

Versions

The Tatra 77 was a hand-built car with leather interior. Some cars had a glass partition between the front seats and the rear seats. A sliding roof was available.

An interesting feature equipped on a few of the T77 models was the steering wheel in the centre of the dashboard. The front seat passengers were seated on either side of the driver and the seats placed slightly back, as on the modern day McLaren F1. All other T77's had the steering wheel on the right hand side as Czechoslovakia, like various other European countries, drove on the left before WWII.

The unique car pictured here is the two-door coupé prototype used by Erich Übelacker. This one also had the more powerful engine from the latter Tatra 87.

Further development

Ledwinka was not entirely satisfied with the T77's handling, caused by its rather heavy rear. He started work on a successor to the T77, which was to be less heavy and with an improved weight distribution. Tatra achieved just that with the now famous Tatra 87^[17] that was introduced in 1936.

See also

• Tatra (car)
• Rumpler Tropfenwagen - aerodynamic car from 1921, of which about 100 units were built
• Chrysler Airflow

References

External links

Wikimedia Commons has media related to Tatra 77.

• Jay visits John Long at Pebble Beach to get a close-up look at his rare Tatra 77a
• Tatraclub.at: Tatra 77a riding (video)
• Tatraclub.sk: Contemporary T77 materials
• Tatraworld.nl: List of T77s known to exist today
• Original brochure (czech)
• Gallery of beautifully restored silver T77a

Tatra models Cars NW Präsident NW A NW Elektromobil NW B NW C NW D NW E NW F NW J NW L NW S NW T NW U 10 11 12 17 20 26/30 26/52 30 30/52 31 52 52 Sports 54 57 57A 57B 70 70A 75 77 77a 80 87 87-603 97 600 Tatraplan 603 2-603 613 623 700 Civilian trucks: NW First Truck NW TL-2 NW TL-4 13 22 23 24 25 26 27 27B 28 43 49 50 51 72 74 79 81 85 85A 86 92 111 114 115 128 138 141 147 148 158 Phoenix 163 Jamal 400 500 700 805 810 813 815 815-2 816 Beta Military trucks: 57K 72 82 93 111 805 809 810 813 815 815-2 816 DANA OT-62 OT-64 OT-810 V750 V799 V809 Prototypes and racing cars: NW Rennzweier 12 Targa Florio 30 Sport 84 90 107 116 118 130 131 137 157 201 401 600 Diesel 601 Convertible 601 Monte Carlo 602 Tatraplan Sports 603A 603 B5 603 B6 603 MB 603 Monte Carlo 603 X 604 605 607 607-2 625 803 804 806 Baghira Dolphin JK 2500 microbus MTX V8 Prezident V570 V855 Jamal Evo