4 replies to this topic

[Henk]

In the 1980s, I was involved in some research related to the chemistry of Buna-S and other early rubber substitutes used in tyres of WWII aircraft. Rather to my surprise, I now learned from the report in the Austrian newspaper Reichspost covering Rosemeyer’s accident, that … to some extent he owed his big successes also to the performance of the German synthetic rubber ”Buna”, which is very heat-resistant and was therefore less affected by the frictional heat at top speeds than natural rubber.

Rubber was the weakest factor in the efforts of Nazi Germany to attain economic self-sufficiency and complete independence of imports of essential raw materials in time of war. In 1933, with gouvernment funding, IG Farbenindustrie initiated an intensive programme to produce Buna-S in large quantities. Developed and patented by Walter Bock and Eduard Tschunkur, mass-production of raw Buna started in 1937 in Schkopau and Leverkusen.

IG Farben had also the patent rights for Buna-based tyres. In 1933, German tyre manufacturers were still reluctant to experiment with Buna compounds. But Farben mobilized the Ministry of Economics to make clear to the management of Continental Gummiwerke that effective cooperation was expected of them. Also smaller German firms, such as Deka and Metzler, became involved in experiments with Buna.

In 1936, tyres made from Buna-S were put on display at the Berlin Motor Show, while Deka started limited commercial production. Yet, as far as I know, it took considerable time before German tyre industry had fully converted their production lines to the use of synthetic rubber.

But apparently Continental considered the properties of Buna-S to be good enough for immediate application in racing tyres.

Perhaps Silberpfeil-experts can shed some more light on the Why, When and Where of Buna-based racing tyres?


Reichspost 29-01-1938:

[Holger Merten]

What happend. This interesting thread had no response?
Interesting material Henk. I have to check my sources about your informations. I'm interested in any kind of more information (e-mail?). Tyres and aerodynamics are very interesting technical topics from that time.

[Henk]

Holger - Apparently pre-WWII application of synthetic rubber is still a little-explored aspect of motor sports history….

On the web I traced a few references that at least confirm the use of Buna in 1937…

Leif Snellman's pages:
http://www.kolumbus....llman/gp371.htm

28-29 APRIL 1937: Daimler-Benz and Auto Union conducted a second test session at AVUS. Mercedes used a 1936 GP car and a new streamliner with the 5.58 litre V-12 engine. Auto Union came with a streamliner that had the present GP chassis and engine but the fully enveloping body . These three cars put in many laps over the next two days doing aerodynamic tests and finding out about handling, tires and fuel. […] The tyres caused the main problem, with the wear highest on the left rear. The latest 24" tyres from Continental, made of synthetic Buna-rubber only surviving four laps at top speed by von Brauchitsch.

South-African pages on DKW and Auto Union history:
http://www.dyna.co.z...rs/history2.htm
http://www.dkw.co.za/history.html

In 1937 these cars were also racing in South Africa. Extracts from the newspaper reports read as follows: "...on East London's Prince George Circuit, they flabbergasted spectators with lap speeds of 115 mph and a fantastic 180 mph top speed." At the Pollsmoor Circuit in Cape Town the following was said: "Although the great white cars started more than half an hour behind half the field and had to make several pit stops to change their synthetic rubber tyres, they took the first two places.... "

The AUTO UNION racing team arrived in South Africa by ship after some weeks with all their spare parts, tools, fuel, oil, tyres, etc. in order to tackle the competition, the climatic conditions and the local rules in the three race series. The local racing fundis of those days commented on the “bad quality” of the German Continental synthetic rubber tyres while they were lasting only 12 laps. Berndt Rosemeyer requested the fitment of the “best” available tyres which could be found locally. After only 4 laps, the 500 hp 16 cylinder supercharged power plants wore them down to the canvas. This changed the tunes of the so-called fundis.


Perhaps a related question….
Today, early synthetic compounds such as Buna-S are still widely utilized in racing tyres.
I wonder if there is any information on the re-introduction of synthetic rubber after WWII.

When? - In the 1960s? Or perhaps already in the 50s?
Who? - Dunlop? Or perhaps Goodyear and/or Firestone who, after Pearl Harbor, had already been deeply involved in the production of Buna-based tyres?

[dmj]

Originally posted by Henk
[I]In 1937 these cars were also racing in South Africa. Extracts from the newspaper reports read as follows: "...on East London's Prince George Circuit, they flabbergasted spectators with lap speeds of 115 mph and a fantastic 180 mph top speed." At the Pollsmoor Circuit in Cape Town the following was said: "Although the great white cars started more than half an hour behind half the field and had to make several pit stops to change their synthetic rubber tyres, they took the first two places.... "

Why white???

[Henk]

Originally posted by dmj
Why white???

Apparently, Silberpfeile were like chameleons, ever changing their colour to fit in any local environment….


I just came across this note about the ‘golden’ one in Prague:

Sam Beckwith, for The Prague Post

Among the jewels of the collection is a beautiful Mercedes Benz W154/M163 Grand Prix model from the late 1930s. The car, raced by Italian-German driver Rudolf Caracciola, is the only one of its kind still in its original condition. While a preservative has been applied to the peeling golden paintwork to prevent any more deterioration, every other aspect of the car is as it was on the starting grid. According to museum director Karel Zeithammer, "Even the air in the tires is from the 1930s."

Air from the 1930s seems a somewhat exaggerated claim in support of the car’s original condition.

Although it could be argued that application of Buna had improved resistance to atmospheric aging of Continental racing tyres, air-tightness of inner tubes may be a different story.

Because of relatively high permeability to air, deflation of inner tubes made of natural rubber cannot be prevented. Only after 1943, pressure loss in tubes could be reduced by applying the butyl rubber, developed at Standard Oil of New Jersey by Robert M. Thomas and William J. Sparks. Permeability to gases of this synthetic compound is significantly lower than that of natural rubber.

Air of the 1930s should have already disappeared as the car was roaming around through the collapsing Third Reich, before getting to the Prague museum.

But this is all theory, so I would appreciate to hear about experiences with air-tightness of prewar tubes.