Mercedes T80: The fastest car in the world–if it were ever finished
by Peter Brock
The years just before World War II were some of the most exciting and technically interesting for motorsports enthusiasts everywhere. A handful of the most visionary minds in Europe and the U.K. were developing concepts that would remain dominant in the field for years to come.
One particular hotbed of innovation was the battle for the worlds land-speed record being waged among several wealthy privateer sportsmen in England. The Germans had the tantalizing potential to defeat them, armed with the technical superiority and financial backing of the rising Nazi regime, but they had other priorities.
The Germans were on a quest for Grand Prix dominance against the tenacious Italians within Maserati and Alfa Romeo. At the same time, Germany’s two Grand Prix teams, Auto Union and Mercedes-Benz, were locked in a surprisingly intense internal rivalry for road racing superiority.
One man, however, pushed for a change in focus. Famed racer Hans Stuck wanted to use those government resources and technology to bring the prestige of the land-speed record to Germany.
In 1936, Stuck was determined to be the fastest human on Earth. He was among the elite few capable of taming the powerful mid-engine Auto Union Grand Prix racers of the era, and he began using his considerable influence to convince personal friend Adolf Hitler and several high-ranking members of the German government that his land-speed dream was feasible.
He and Dr. Ferdinand Porsche had already been working together at Auto Union since 1934, when Stuck used one of Dr. Porsche’s specially prepped 4.4-liter, mid-engine Gran Prix racers to run a 134 mph average on the Avus circuit. This particular Type A racer was actually capable of some 174 mph, but the tight turnaround at one end of the Avus track limited Stuck’s record speed. Still, this feat was considered of great propaganda value in Europe.
With government approval and financing of his land-speed record plan, Stuck then approached Mercedes-Benz’s cautious management to inquire if they might allow the use of one of their state-of-art, supercharged DB600 W16 aero engines, then being tested for the Luftwaffe’s Messerschmitt Bf 109 fighter planes. At that time, the DB engine’s 33.9 liters produced some 2500 brake horsepower.
Mercedes agreed, then hired on Dr. Porsche to the project; his contract at the manufacturer’s archrival, Auto Union, had just expired. Equipped with the powerful aircraft engine and Dr. Porsche’s imaginative design genius, the Porsche-Stuck collaboration was expected to easily top British contender Malcolm Campbell’s then-current record of 301.129 mph.
Fighting Physics
Simple physics decrees that the speed of any object passing through the air is limited by aerodynamic drag. In fact, drag is squared whenever the speed doubles. Even more daunting, going twice as fast requires the engine power to be cubed.
By the late 1930s, it was readily apparent to those chasing land-speed glory that reducing their vehicles’ aerodynamic drag was vital. As a result, they abandoned their open-wheel racers for absolute record-setting attempts. Dr. Porsche, Hans Stuck and Mercedes-Benz hoped to make their racer the fastest car on the planet, but it didn’t quite go as planned. Prix-style machines suffered from tremendous aero drag, half of which was created by the stark frontal area of their wheels and tires.
Dr. Porsche wisely analyzed the competition and determined another factor that would give his effort the edge: limiting total vehicle weight. The mass of the existing British cars, coupled with 1930s tire technology, would eventually limit their terminal speeds. Their treaded tires could barely support all that weight while enduring the destructive centrifugal forces that come with speeds above 400 mph.
“Their treaded tires could barely support all that weight while enduring the destructive centrifugal forces that come with speeds above 400 mph.”
Stuck’s vision for his record attempt hinted at divisions that were becoming apparent at the top of the German government. He had highly nationalist fantasies of a car designed and manufactured in Germany, riding on German tires, with a German at the wheel, making land-speed history on German soil.
But Dr. Porsche, an engineering realist, knew the last part of Stuck’s plan was impractical and dangerous. Only the broad expanse of Bonneville was suitable for the speeds they envisioned, so he quietly assumed their mission would take them to America. And when a colleague died during a 1938 record attempt on the Autobahn, Stuck shifted to Dr. Porsche’s point of view. They agreed to set their sights on the salt flats.
Soon after, Dr. Porsche, Stuck and renowned aero expert Joseph Mickl began designing an innovative shape for their collaboration with Mercedes-Benz. The new project was designated the T80. Hitler named it Der Schwarzer Vogel, the black bird emblem of the Nazi regime.
Of course, the team’s 350 mph goal had become obsolete and was getting more dated by the passing months; they’d not yet realized that the English teams were already poised to exceed 350 mph. Once the team realized the need to reassess and adjust their target speed, Dr. Porsche, Stuck and Mickl recalculated the possibilities for their existing design. Their findings? They’d need more power. They requested that Mercedes engineers build a very special 44.5-liter, supercharged, 3000-horsepower version of their DB aero engine to power the T80, which Dr. Porsche now projected would run at an incredible 466 mph.
Big speeds required big power: some 3000 horsepower courtesy of 44.5 liters.
Unaware of what the Germans were planning and undaunted by Eyston hitting the 350 mark, Cobb again returned to the salt in August of 1939, just as World War II was dawning. He clocked an impressive 369.74 mph.
Days later, the outbreak of WWII halted land-speed competition for almost a decade, killing any possibility of the German T80 vehicle competing in Bonneville. In fact, the super-secret land-speed racer was hidden away for the duration of the conflict.
Had the war not interfered with the Germans’ plan to capture the record from the British, Dr. Porsche’s radical Mercedes-Benz T80 could have topped Cobb’s final attempt. Even today’s official wheel-driven record of 437.183 mph, set by American George Poteet in his Speed Demon, is still well short of Dr. Porsche’s predictions for the T80. If this vehicle, conceived some 80 years ago, were completed today to Dr. Porsche’s original specifications, it could likely run to 460 mph and beyond.
THE T80’s ADVANTAGES
Light Weight
Instead of the 5-to-7-ton weight of the British-built cars, Dr. Porsche had wisely set a “light” target weight of some 2.5 tons for the T80. He did so to both relieve the pressure on the car’s four driven tires and allow better acceleration on the possibly less tractive salt.Early Downforce
To offset the “unknown” conditions of Bonneville (no German had yet raced on the salt, and traction actually did change from year to year depending on moisture), Dr. Porsche and aero consultant Joseph Mickl integrated two large inverted airfoil wings midship. These wings would increase downforce as speed increased.Traction Control
A clever traction-control system would theoretically eliminate any wheel spin from the four driven wheels. The system used a pair of flexible cables, similar to those found controlling a speedometer. One ran from the rear driven wheels while another was connected to a non-powered front wheel; the cables met at a differential device on the engine’s fuel-injection pump. If the system sensed that the driven wheels were spinning faster than the fronts, the injector pump would detect the difference and cut fuel flow to the engine.Slipstream Shape
The futility of trying to increase speeds with open-wheelers finally convinced Mercedes-Benz’s eternally shrewd team manager, Alfred Neubauer, that full-envelope bodies were required to top 250 with any sense of safety.Narrow Body
The main body of Dr. Porsche’s T80 would also be much narrower at just 69 inches. His six-wheeled, mid-engine creation was an amazing 26 feet, 8 inches in length, with the supercharged engine taking up most of the room.Exotic Power
The Mercedes-Benz 44.5-liter engine, a special variant of the basic DB design, was expected to deliver some 3000 brake horsepower on an exotic mix of methyl-alcohol, benzine, ethanol, acetone, nitrobenzene and av-gas-with a slight amount of water added to prevent detonation. Supercharging this huge engine was, of course, necessary to offset the deleterious effects of thinner air at Bonneville’s 4219-foot altitude.
The Records
MARCH 29, 1927
203.79 mph
On the sands of Daytona Beach, Henry Segrave becomes the first person to break 200 mph in his Sunbeam-powered Mystery. This marks the beginning of an intense period of land speed battles among British drivers.
MARCH 7, 1935
276.00 mph
Malcom Campbell posts a record in his Blue Bird on Daytona Beach. He realizes the conditions there are too unstable for higher speeds, so he plans his next assault for the Bonneville Salt Flats.
SEPTEMBER 3, 1935
301.13 mph
Campbell finally breaks through the “triple” at Bonneville.
NOVEMBER 19, 1937
311.42 mph
Captain George Eyston takes on Bonneville in his huge, eightwheeled Thunderbolt, propelled by 5000 horsepower from a pair of Rolls-Royce engines.
AUGUST 27, 1938
345.49 mph
Eyston ups the ante. Afterward, he cagily claims that he’s “retiring from competition,” hoping his record will stand.
SEPTEMBER 15, 1938
350.20 mph
It doesn’t. John Cobb hits the salt and boosts the mark with his Railton Special, equipped with two supercharged 23.9-liter Napier Lion engines.
SEPTEMBER 16, 1938
357.50 mph
Eyston retaliates within 24 hours in his 7-ton monster, then finally sails back to England.
AUGUST 23, 1939
369.74 mph
Cobb and his Railton Special return to land an impressive official two-way speed.
SEPTEMBER 1, 1939
WWII begins
Hitler invades Poland, setting in motion a conflict that both prevents the Brits from traveling to Bonneville and ends the German T80 challenge effort.
SEPTEMBER 16, 1947
394.6 mph
After the war, Cobb returns to the salt flats with his Railton for the final time and breaks his 8-year-old record.
AUGUST 5, 1963
407.45 mph
First to 400: American Craig Breedlove and his three-wheeled, jet-powered Spirit of America mark the transition from wheel-driven to jet- and rocket-powered vehicles.
JULY 17, 1964
403.10 mph
Donald Campbell, Malcolm’s son, arrives at Australia’s Lake Eyre and elevates the wheel-driven record in his CN7 Bluebird, an all-new design with revolutionary gas turbine propulsion.
OCTOBER 15, 1964
526.28 mph
At Bonneville, Breedlove and Spirit of America are first to breach 500 mph.
NOVEMBER 12, 1965
409.28 mph
American hotrodders Bob and Bill Summers buck the aeromotive trend, raising the wheel-driven record in their Goldenrod streamliner powered by four fuel-injected Chrysler Hemis.
NOVEMBER 15, 1965
600.60 mph
Breedlove topples another barrier at Bonneville, this time in Spirit of America Sonic I.
from:
https://classicmotorsports.com/articles/mercedes-t80-land-speed-car/
