Sunday, November 22, 2020

BIOS Final Report No 922 - Tatra Car, Type 87, V8 Air Cooled Engine at Rear


In the aftermath of the Allied victory over Germany in the Second World War, the western allies established an intelligence sub-committee to investigate and analyze German technology. Technicians and specialists delved into every aspect of German industry, from aeronautics, optics, electronics, radio, chemicals, mathematics and, of course, automobiles. The Americans had little interest in German automobile technology, but the British were very interested. Every type of German vehicle they could get their hands on were shipped to Britain and studied. Vehicles studied included the Auto-Union and Mercedes Benz Grand Prix cars, the DKW F9 prototype (the Werner car https://dkwautounionproject.blogspot.com/2017/07/1939-dkw-f9-prototype.html) and, most famously, the KDF Volkswagen. The Volkswagen was passed to the Rootes Corporation for evaluation. Rootes dismissed the Volkswagen as 'not meeting the minimum requirements of a motor vehicle' and the rest, as they say, is history. Assessing new technology and unorthodox designs was not a strong suit of the British auto industry, which remained wedded to traditional techniques and concepts.

Vauxhall Motors received a Tatra T87 former staff car for evaluation in 1945. The car was in terrible condition, with its suspension shot, engine out of tune and a different set of tyres and rims on each of the four wheels. The car not repaired but tested 'as is' and, consequently received a very poor evaluation. The Vauxhall report warned that the type was dangerously unstable at anything above a medium speed, concluding with the assessment that the T87 was effectively a bad design with nothing to be learned.

Many of the criticisms in the summary are niggardly and superficial, such as complaining about the floor mounted gear shift impeding the driver and front passenger from switching seats - this is inherent in all floor mounted gear shifts. Similarly the luggage compartment being behind the rear seat - again, a very common feature in cars from the 1930s which did not have an external opening boot. This only became a standard feature in the 1940s. These weak arguments reveal that the examiners were not really interested in learning from unorthodox.

If the British auto industry were really interested in evaluating the Tatra, they could have tested the T87 of Captain Fitzmaurice, who had owned one since the late 1930s. Fitzmaurice's car would have been maintained and performed as designed, but that was not the purpose of these reviews, which were propagandist in nature. There was nothing to be learned from the Germans and the British motoring industry could continue as it always had, free from new ideas.

I have been searching for years for a full copy of the BIOS Report No 922, but have never been able to get my hands on on. This is from a scan of three introductory pages. If anyone has a copy they would like to share or sell, please let me know.

Report on Rear Engined V8 Tatra Car Type 87

Foreword

Following arrangements made by the British Intelligence Objectives Sub-Committee and the S.M.M and T regarding material from Germany, the car was made available to this Company for trial.

Because of its unorthodox design, the Tatra possesses many features of interest, most of which have been commented on in this report.

The report is by no means exhaustive, as no attempt was made to carry out a strip-down, detailed weight analysis or bench test, but rather to check up and report upon the general effect from the user’s point of view of this rear-engined layout. The various specific tests included are those which we considered to be of interest and capable of execution in the time available.

M.A.Dean
Passenger Vehicle Experimental Engineer,
Vauxhall Motors Limited.
Luton
15th July 1946

Page No 4.

Summary and General Conclusions

The designers of this unorthodox car have produced a vehicle that is full of interest, having several very good features. Although the body is of striking design, this has not been accomplished at the expense of the passenger accommodation, on the contrary the front seats are of generous proportions and the rear will accommodate three persons in real comfort.

The weight distribution is of particular interest being 30% at the front and 62% at the rear (see page 14). The rear engine location gives the considerable advantage if maintaining an approximately constant ratio of front to rear wheel loading irrespective of the number of passengers carried. This advantage is however more than offset by the fact that under all load conditions the vehicle is inherently unstable at moderately high speeds. It is surprising to find this characteristic in a powerful streamlined car fitted with a high gear ratio and presumably intended to be capable of sustained high speed autobahn travelling.

Noise measurements inside the car show up very favourably when travelling above 30 m.p.h. in top gear, despite the fact that the engine was particularly noisy, (partially due to the fact that it was air cooled, aggravated by its poor general condition). This is one of the advantages of locating the engine in the rear. No doubt a water cooled engine so placed would result in a body exceptionally free from airborne engine noise, although any additional weight at the rear could not be tolerated.

One cannot help feeling that the benefits of some of the original ideas incorporated have been largely nullified by the adoption of constructional features rendering it impossible to take full advantage of the layout. For instance the adoption of an internally housed backbone frame has made it impossible to obtain a low flat floor, which is one of the great advantages that can be gained when the propellor shaft is dispensed with. The gear lever and handbrake are located on top of the backbone frame making it impossible to move readily from one front seat to another.

The forward driving position combined with the windscreen side glasses result in excellent forward vision. The front wheel arches protrude into the toeboard making it necessary to incline the legs inwards slightly, some people found this uncomfortable. In an effort to get some of the weight forward, the two spare wheels, the two batteries, and even the petrol tank have been placed in the front. With the front and the rear thus occupied the luggage accommodation has had to be situated behind the rear squad, limiting its capacity and adaptability, also making it necessary to disturb the rear passengers to obtain access to it.

A study of this rear engine car from the point of view of disposition of passengers and luggage, tends to confirm the view that the space available in a passenger car is more usefully employed when the engine is located between the front wheels, and the luggage, petrol tank, spare wheels etc., located in the rear.

The effortless motoring at medium speeds in top gear, good ride over rough roads, and silence at normal road speeds are worthy features, but must be remembered that the car is high priced coming well into the luxury class.

Description.

Engine:
The power unit is placed behind the read axle. The cylinders of the V.8. air cooled engine are arranged at 90 degrees. The cylinders are separate, each assembly consisting of a cast iron cylinder barrel with machined fins and an individual light alloy head having cast fins. Light alloy pistons with two compression and one scraper ring are fitted.

The engine compartment is divided up so that cool air is sucked in viz. each side scoop and drawn past the cylinders into the inner chamber and from thence blown out through the back louvres.

The two air cooling blowers are belt driven, one from a V. pulley on and extension of the crankshaft and the other from a pulley off the timing gear drive. Belt adjustment is obtained by moving the actual blower motors outward in their casings, the adjustment nuts are at the rear of the engine and reasonably accessible. The two overhead 5 bearing camshafts are chain driven from the rear of the crankshaft.

On the front of the left camshaft is a pulley driving the dynamo by means of 2 V. belts while the other camshaft drives the distributor.

For more of Tatra posts check out my dedicated Tatra blog: https://tatrat600.blogspot.com/