Tatra Streamline: Tatra T77

English customers and engineering firms were extremely conservative and observed developments on the continent with some degree of disdain. In February 1935, 'The Autocar' provided their readers with an evaluation of the new Tatra T77. It is interesting to note that while the authors do not believe the Tatra or similar vehicles will appeal to English customers, overall they are extremely positive about the car's technical development and performance. Again - and I am always stressing this based on the contemporary documentation - the authors comment on the car's excellent handling, especially over rough, pot-holed ground. No mention at all about rear-end instability and tricky handling.

This Year, Next Year...

Probably Not, in Any Large Numbers for Motorists in This Country: But the New V8, Air-cooled, Rear-engined Tatra is a Design of Great Interest, and Embodies in Principle the Ideals of Many Designers

Those who follow the international design and development of cars more than superficially often find it interesting, even if not profitable to think ahead and try to form some idea of what shape and construction the car of a few years hence will follow.

There is a great deal of truth in the statements sometimes made that owners in this country, and therefore the manufacturers who attempt to interpret the demands of their clientele, are apt to regard with a degree of suspicion any machine which breaks very drastically away from the shape and kind of car to which we have been accustomed basically for a considerable number of years. As is clear from designs which have appeared, and, still more important, which have sold to the public, the position on the Continent is decidedly different. Quite a number of departures from orthodox practice have gained acceptance among car users in France, and particularly in the Central European countries.

Designers all over the world are experimenting with features which they consider to be desirable. These include (1) independent springing, already adopted by some British manufacturers for the front wheels and by certain Continental firms on all four wheels; (2) rear engines, again something which is not entirely new; (3) air cooling, a type of engine from which the Franklin Company has never departed; (4) distortionless frames, a problem tackled by most designers by stiffening existing designs; (5) streamlining, a question which has been left mainly to the body designer; (6) passenger load within the wheel centres. All these things have been done, but very few designs incorporate each of these ideals.

A manufacturer to be instanced as having steadily pursued a policy of building cars entirely different in such important matters as frame construction, suspension, and body outline, is Tatra, a Czechoslovakian firm with works at Prague. The latest model from these works does embody all the points enumerated.

A good many people in this country are acquainted with the small air-cooled Tatra cars embodying independent suspension of all four wheels in conjunction with a tubular "backbone" type of frame, ordinary frame side-members being eliminated. Now there comes a development of the main principles of this design in a larger car known in its own country as the Tatra 77 with a V eight-cylinder engine, also air-cooled, which as a whole is a vehicle of considerable overall size and impressive appearance.

lt is to be looked at from two standpoints in this country. First, it is of undoubted technical interest, a proposition which is unconventional, but has experience behind it, and which must be taken seriously. Secondly, one has to admit. the limited selling potentialities of a vehicle of this nature in England in view of ideas generally at the present time and bearing in mind a price necessarily raised by import duties and so forth. That having been said, one can proceed to examine the design from the aspect of a complete breakaway from orthodox practices, as an example of carefully developed streamlining, and as a car built for use in conditions on the Continent which, as regards road surfaces and distances to be covered, are markedly different from those obtaining here.

To start with, the general appearance demands notice. A first impression is not of a vehicle aggressively different in appearance for the mere sake of being so; its shape, which would be described at very first sight by most people as being streamlined, seems to be part of the general conception and therefore to fit in naturally with the scheme of things.

Then comes the layout of the various components, a good idea of which can be gathered from the accompanying partially broken-away view, the main features being the independent wheel suspension, the use of a tubular frame-member of square section running down the centre of the car, to which the body is attached, the rear position of the engine, and the fact that that engine is a V eight-cylinder and air-cooled.

The idea behind the car is that it shall be fast and exceedingly comfortable, a maximum in the region of 90 m.p.h. being possible, but, above all, that its cruising and average speeds shall be high, that it shall work easily by virtue of a high top gear, and the wearing parts therefore possess an unusually long life.

The engine itself, disclosed by lifting a hinged lid which forms the tail of the car, is a remarkably compact unit, in external appearance unlike almost any other existing type of car engine.

Two banks of four cylinders are set at an angle of 90 degrees one to the other, but the V construction is not immediately apparent. Overhead valves are operated directly through long fingers or rockers from a centrally situated camshaft, the crankshaft has three main bearings. The engine being air-cooled, the actual cylinder barrels are visible on looking into the details, and they are provided with fins for cooling purposes. The cylinders are surrounded as a whole by a jacket which, broadly, is open on the one side to the entry of cooling air delivered under pressure from a sirocco fan, and at the other side to permit the exit of the heated air after it has done its work.

In the cowling which covers the engine unit - the bonnet in effect - there are louvres facing forward in the air stream, through which cool air is admitted to the pump or fan casings, each block of cylinders having its own fan, driven at engine speed by a belt direct from the crankshaft. Engine bore and stroke, by the way, are 75 by 84 mm. (2,970 c.c.). and the rating here is 27.9 b.p.

The engine auxiliaries are neatly and accessibly arranged. At the rear of the unit is an AC diaphragm type of petrol pump which draws fuel from the very large tank placed at the front of the car. Bosch electrical equipment is used. At the centre of the engine block is a Zenith down-draught carburetter.

In conjunction with the carburetter there is a hinged metal hood or slide which has three positions and which can be regulated so as to control the admission of air to the intake. It is possible to arrange either that fresh cold air enters the carburetter after coming into the engine compartment, or that the carburetter be shut off entirely as regards the external atmosphere and receives only heated air rising from the cylinders.

Lubrication of the engine is by a dry sump system, oil being held in a reservoir on the off side of the crank case and passing in its circuit under pressure through the engine into radiators exposed to the cool air stream.

Points to Remember

lt is necessary to bear in mind the general construction of the car in appreciating the fact that there is no ordinary frame, and that axles of the normally understood type are not used either, the rear wheels being sprung by a wide transverse spring. Towards the rear, the " backbone " frame ceases, and thence rearwards extends a forked construction of tbe frame to receive, first the gear box, then the final drive housing, and the clutch casing, to the flange of which is attached the engine unit itself. The unit as a whole is mounted at three points, one in front, the other two consisting of the extremities of a cross-tube attached in rubber to the fork.

The engine overhangs what is in effect the rear axle, but is compact to such an extent that the amount of this overhang is not more than about 25in., balanced very closely on the forward side of the "axle" line by the final drive and gear box casings.

Between the rear and front wheels there is no mechanism whatsoever except for the control links, and the tubular frame extends forward to the point where the front wheel suspension, again consisting of a transverse spring, and the steering gear are mounted.

The throttle, clutch, gear, and handbrake controls pass through the central tunnel to the rear of the car. Helically toothed pinions in constant mesh are employed in the four-speed gear box for second, third and the direct top gear, but a synchromesh or other form of easy gear change is not employed. The gear ratios are, on top 3.75 to 1, third 5.92 to 1, second 10.12 to 1, first 15.52 to 1. The engine speed at 60 m.p.b. is approximately 2,700 r.p.m., whilst the power output reaches a maximum of 60 b.h.p. at 3,500 r.p.m.

Remarkable Carrying Capacity

Apart from the very real mechanical interest of the car, the whole point of it from the riding aspect is the manner in which the special construction of the chassis permits a remarkable ratio of carrying and load capacity in relation to the car's wheelbase. One is immediately struck by the extreme width of both front and rear seats; the rear seat will very genuinely accommodate three adults, the front also is sufficiently wide to take three, but there is the complication of the central gear and brake levers. Apart from the by no means serious intrusion of the central frame-member, the back compartment floor is left clear and unobstructed; on either side of the tunnel is an area some 25 in square, and leg room is exceptionally good.

Rough measurements showed that the interior capacity effective dimensions are equivalent almost exactly to the overall length of the car (17ft. 1in. overall, with bumpers).

The style of the interior, with leather upholstery and good detail equipment, is very pleasing; there is luggage space behind the back seat squab, shut off from the interior of the car by an apron.

The windscreen, it will be noticed, has a marked inclination from the vertical; the side panels which it incorporates increase width of vision, and these are made of curved safety glass. In the centre of the screen at the top is a small, rectangular opening controllable by a flap that can be hinged from inside. The object of this is to give ventilation to the interior without it being necessary to open the windows in bad weather.

lt is most noticeable, sitting in and driving the car, that the windows occupy a considerable proportion of the side area, and thus a light interior and excellent vision are obtained.

In the nose are carried two spare wheels and the larger tools, such as the jack and its appurtenances, also the reservoir for the one-shot lubrication and the hydraulic brake system. Warmed air is led from the engine to the front compartment, the supply being regulated by a shutter.

The head lamps are not recessed entirely flush with the body, but from the streamlining point of view the tail is treated as mattering more than the front, and there is the important point that the underside of the Tatra presents a smooth, flat surface unbroken by any excrescences, still retaining a ground clearance of nine inches.

Road Experiences

On the road the car proved to be most interesting to drive, and considering the weight, 33 cwt., and the size of the engine, 3 litres, it had a good turn of speed, and was not unduly sensitive to changes in gradient. The riding was most comfortable, and a demonstration at speed down a hill abounding in potholes and such obstructions as manholes standing high above the ground was, to say the least, astounding. None of the party of four in the car would have dared to have taken any normal car over the surface in question at half the speed. Yet inside the car very little shock was felt, and there was none of those disconcerting shocks which suggest that machinery is being ill-treated.

From English standards the engine and gears are noisy, but this is not apparent to the driver and his passengers.

The price put on the car here is 990 Pounds, and the concession for the British Empire is in the hands of D. Fitzmaurice, 122A, High Street, St. John's Wood, London, N.W.8; Airstream, Ltd., 83, Davies Street, London, W. 1, are distributors for London and the Home Counties.