18 replies to this topic

[Dennis David]

Rosemeyer in describing his record setting run stated that "... at about 240 mph the joints in the concrete road surface are felt like blows, setting up a corresponding resonance through the car, but this disappears at a greater speed. Passing under bridges the driver receives a terrific blow to the chest, because the car is pushing air aside, which is trapped by the bridge. When you go under a bridge, for a split second the engine noise completely disappears and then returns like a thunderclap when you are through.

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Regards,

Dennis David
Grand Prix History

Life is racing, the rest is waiting

[Ray Bell]

Mercedes built a car to try to take the world LSR in the outright category. I read about it some 36 or 37 years ago and have never seen anything on it anywhere else. It had petrol aircraft engine(s) and had a form of traction control, and I think also anti-lock brakes...
Hitler wanted the job done on one of his Autobahns, so they were up against it compared to the room available at Bonneville.
Anyone got anything more on that one?
The attempts I really liked were those from the Summers brothers and Mickey Thompson, hot rodders to the end!

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Life and love are mixed with pain...

[buddyt]

Frank Lockhart had been clocked at 198.29 mph by the AAA officals on his previous southbound warmup pass. Lockhart's small body was flung from the car at the wrecks end like a bunch of rags. It landed in a crumbled mound at the feet of his horrifed wife. Shortly after celebrating his 26th birthday Lockhart was dead. Frank Lockhart had put all of his funds into building the car "Black Hawk" and his pursuit of the world speed record. He died completely penniless. Area residents responded with a large sum of money which speed week organizers gave to the newly-widowed Mrs. Lockhart. She promptly left town with the money, leaving her dead husband's body in a Beach Street mortuary. The body of Lockhart lay there while promoters passed the hat a second time. Again, funds were gathered. Finally, after several months, young Lockhart's body was shipped home to California....... From the book DAYTONA the quest for speed, telling of Frank Lockhart's April 25th 1928 land speed record attempt.

[Leif Snellman]

I recently added a speed record section to my homepage and yes, the 44 1/2 litre Mercedes-Benz T80 LSR car is included (see under 1940).

The address is:

http://www.kolumbus....ellman/reco.htm

[Ray Bell]

Thanks, Leif... long time no information!

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Life and love are mixed with pain...

[Michael M]

Some more information about this project. Hans Stuck in 1936 had the idea to break Campbell's land speed record in. He was still one of the top drivers of Auto-Union, but his position was endangered by young Bernd Rosemeyer, so he was in need of some publicity. He had good personal contacts to Professor Porsche, not only by their mutual work for AU, but Stuck was also investor when Porsche founded his own construction office at Stuttgart. Porsche was so enthusiastic about this idea that he offered to work on the project free of charge.

The main problem was the engine power, Campbell's Bluebird used a 2500 HP RR aero engine, and for reaching 500 km/h Porsche calculated 3000 HP to be necessary. Strongest engine available was Mercedes-Benz' DB 600 with 1000 HP resp. DB 601 (fuel injected) at 1300 HP. However, these engines had been available as prototypes only, ordered by Ministry of Aviation. Director of its procurement department was Ernst Udet, flying ace in WW1, and a close friend of Hans Stuck, and so it was rather easy to get Udet's agreement to receive 2 of these engines.

Next step was to find somebody to build the car, as Porsche was only able to do the theoretical work. Auto-Union was not interested, the project was too expensive, and they had enough to do with their GP cars. So Stuck went to his old friends at Mercedes-Benz. Director Kissel was not pleased that Porsche was involved in the project, because there was still some kind of rivalry between them dating back to Porsche's MB period. On the other side he was afraid that if MB is not doing the job, Stuck will take the 2 engines,which legally had been owned by Ministry of Aviation, to get the car build by one of their competitors. And of course this was not in the interest of Mercedes-Benz! So they finally agreed, under the condition that Stuck will find finance for the project. Based on Porsche's system of running project numbers, the car was the type 80, or T80. Expected delivery date was end of 1937.

Porsche started the construction, and also DB made some progress in engine development. The latest version of DB 601 was able to reach 2000 HP, and so Porsche proposed change of the concept, using only one engine instead of 2, saving considerable weight. Theoretical calculations gave a speed of 550 km/h after 5 kms, based on 2200 HP, or better 2500 HP. In November 1937 the team was shocked by the news that George Eyston with his "Thunderbolt" set the new mark at 502.1 km/h, claiming to have sufficient reserves for further increases. This delayed the project, because there was no way to achieve the now necessary higher engine power, and also the work on the new GP car, the W 154, set preferences. Late summer 1938, just when final assembly of the car started, the latest news came in: Eyston reached 556.0 km/h, increased by John Cobb with his "Railton Mobil Special" to to 563.5, only to be topped again by Eyston with 575.3 km/h!

Porsche had to revise the whole construction by setting the new target to 600 km/h, for which he calculated 3000 HP to be necessary. The new DB 603 aero engine was under development, and engineers believed they can reach this level. Work on the T80 chassis went on, and early 1939 an DB 603 engine was installed for the first time. It would go too far to describe all the technical details, but remarkably is that the T80 had 3 axles, with power transmission to the 2 rear ones. Also interesting is that the T80 most likely was the first car using reversed airkraft wings for achieving ground effect, a thing today we call "spoiler". Including bodywork, but without driver and fuel the car weighted 3024 kgs.

Problem was still the engine. The DB 603 in its strongest development version still had only 2800 HP, and as Cobb increased the record on August 22 to 595 km/h, this was considered not being sufficient. In october the car was tested on the Rennabteilung's testing bench, and all details which needed fixing and changing would need another month or so. However, due to the war the project was stopped, and later even mothballed. There had been intentions to continue after the war, but when John Cobb in 1947 set the mark to 634.4 km/h, they finally gave up.

[Roger Clark]

I'm not sure about the title of this thread, as I thought all the cars under dicsussion used alcohol based fuel..

Pedantry aside, it's amazing to think how close the German cars were to the absolute LSR. In March 35, Campbell set a record at 276mph. In January 1938, Caracciola did 268mph on a normal road. I know that Campbell and Eystin had moved things on a bit in the meantime, but it does make you wonder whether DB could have followed the Black Hawk Stutz/Goldenrod route and gone for the LSR with a "Bimotore" version of the W125.

[Michael M]

At least in the case of MB and AU it was no pure alcohol (Methanol), but a mix of alcohols, aromatics, and premium gasoline, similar to what they used in the standard GP engines. So one can still call it "gasoline". Believe Dennis' intention was to define Otto combustion engines from jet turbines which use Kerosene.

The amazing thing is not only that the German figures had been achieved on standard roads, but also with modified race cars only, and not with aero engined monsters. The "Bimotore" idea has to be seen under the specific circumstances of the time. Although in 1934 some records had been achieved by both - MB and AU - in class C (3-5 ltr), the real battle only started after Campbell set the mark at 444 km/h resp. 276 mph in 1935 (class A, > 8 ltr). Interestingly MB didn't use their M 25 8-cylinder engine, but the DAB V12, which had been developed as GP engine for the W125, but with its 300 kgs was too heavy for the 750 kg formula. This 5.5 ltr engine in 1936 had max. power output of 616 HP, compared to the strongest version of the M25C (4.3 ltr.) 402 HP end 1935, and 449 HP for the M25E / ME25 (4.75 ltr) in mid 1936.

All major record attemps of Mercedes-Benz and Auto Union had been in class B (5-8 ltrs), why they didn't compete in class C (3-5 ltr) with the M25 8-cylinder is not known to me. A twin-engined car on basis of the DAB V12 would have meant class A, but 2 downsized M25 engines would have been within the 8 ltr. limit of class B. However, DB had a power advantage with the DAB V12 against the only serious competitor in class B - AU -, so a "bimotore" M25 was not necessary. End 1935 Campbell set the new mark at 484 km/h / 301 mph, and as a DAB twin-engined car probably would have been able to reach the old record of 444 km/h / 276 mph (Caracciola reached in October 1936 367 km/h / 228 mph in class B), the new target was out of reach. The final stage of the DAB V12 had over 700 HP, but as Eyston meanwhile again increased to 502 km/h / 312 mph, and claiming considerable reserves, any idea of a twin-engined car - if there was one - should have been abandoned.

I'm sure that both companies made theoretical calculations on this topic, but rejected the idea also due to high costs. Don't forget, the record cars had only been modified GP cars, and for a bimotore a complete new construction would have been needed. Another hurdle on the way to the overall record had been the tyres. The special rubbers used by Campbell, Eyston, and Cobb were unsuitable for the Germans, not only by size, but also due to propaganda reasons requiring use of national brand. The Continental tyres used by MB and AU for their record runs had been improved versions of the standard race tyres, but always had been a critical focus. I really doubt that Conti was able to supply tyres suitable for speed of 500 km/h plus. Also during the 3 years development phase of the T80 the tyre question always was a cause of delay. Another major problem was the aerodynamic lift at high speeds. Already at 360 km/h the front axle lift was more than 200 kgs, meaning half of front axle weight pressure. With 1938 speeds of 429 km/h (AU) and 432 km/h (MB) most probably the front tyres nearly lost contact to the track, which in my opinion was also the reason for Rosemeyer's deadly accident - combined with side-wind. The lack of aerodynamic knowledge in those days is shown by Uhlenhaut's advise: "if you realize lifting, we have to put some lead in front".

However, major barrier for any higher speeds had been the rather narrow bredth of the Frankfurt-Darmstadt Autobahn, especially in combination with potential tyre failures and aerodynamic lift. The new track - a stretch of Autobahn near Dessau in East Germany - was only ready in 1939, and as class A record was now at 575 km/h / 357 mph, it was evident that any attack could only be successful with an aero-engined special like the T80.

By the way, if one of you is travelling in Germany by car on the A5 from North to South, take the first parking area after Frankfurt Airport, a few steps into the wood, and you will find the old Bernd Rosemeyer memorial, which marks the place of his fatal accident ...

[Roger Clark]

CAracciola reached 268mph with the DAB engined car (Jan 1938). Maximum speed varies with the cube root of engined power, so a twin engined version would have given him a 25% increase in speed, or 340mph, provided aerodynamic drag was not affected. This is close enough to the record (357mph) to be interesting, and centrifugal superchargers could have done the rest.

It would probably have been possible to maintain the same frontal area with a Bimotore, and the drag co-efficient should be unchanged.

Special tyres would be needed, but they would have been less of a problem than with the 2.5 ton T80. They would have had to go to Utah, but so would the T80

[Michael M]

This calculation is not quite correct, as not only aerodynamic drag must be unchanged, but also the weight. The DAB V12 was 300 kgs, plus some other extras like drivetrain, stronger gearbox, longer chassis and bodywork, would result in approx. 450 kgs additional weight. Based on the (dry) weight of 1185 kgs this would have been an increase of 38 %.

Centrifugal supercharger? The DAB had already 3 (!) Roots superchargers, producing already max possible boost in relation to loss of power needed for the compressor drive. Also don't overestimate Continental's ability to produce high speed tyres in those years. Due to lack of foreign currency there was no natural rubber available, they had to work with the newly developed synthetic stuff (BUNA), which was not equivalent in properties. And going to Bonneville?? My god, first one with this idea would have been put in jail by Himmler himself, German records must be achieved on German soil!! Especially for the T80 a special stretch of highway has been built near Dessau, completely paved including the middle stripe. In case of speed events the highway was closed, and the middle armco removed, so that a nearly 100 m bredth was achieved.

[Dennis David]

Yes my intention was to define Otto combustion engines which used a mixture which included gasoline from jet turbines which use Kerosene.

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Regards,

Dennis David
Grand Prix History

Life is racing, the rest is waiting

[buddyt]

I think now the land speed record is classed wheel driven and unlimited(jets, rocket whatever). So if you had a jet engine that could drive the wheels you could run for both records.

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"Speed cost money, how fast do you want to go?"

[Ray Bell]

The serious point of the T80 was its requirement to do the job on German soil. This was an intrinsic part of the story I read all those years ago, so Bonneville wa definitely not a part of the equation.

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Life and love are mixed with pain...

[Roger Clark]

I've been wrong before, but I thought that maximum speed ocurred where the power curve met the drag curve and was not affected by weight, assuming level ground and sufficient space to reach the maximum.

Secondly doesn't a centrifugal give a better combination of boost pressure, bulk and power loss, assuming you're not concenred about power at low revs. See D-B and other's aero engines, not to mention the V16 BRM!.

As for tyres, my point was that the problem would have been simpler for a lighter car than the T80.

I'll concede on location, but that problem was no worse thn for the T80.

[Michael M]

Hello Roger,
you're correct, the DB 600 series of aero-engines used centrifugal blowers. The additional power was mainly needed in air combat, where the engine revs are always rather high, for standard flight operations this was not really necessary. By the way, I found a drawing of this engine shown here below (hopefully):



Racing engines on the other side need full power over the whole bredth of revs, so for their automotive engines Mercedes-Benz always used roots blowers. The DAB V12 was developed originally for the W125, so roots superchargers had been obligatory. For speed records a centrifugal blower would be okay, but to re-design the engine would have been too expensive.
If one compares the V12 with the straight 8, it is obvious that principally the DAB was the better engine:
1936 ME25: 4479 cc and 449 HP = 94.7 HP/ltr
1936 DAB V12: 5577 cc and 570 HP = 102.2 HP/ltr (final version in 1938/39 even 700 HP = 125.5 HP/ltr).
This shows that the V12 in 1936 was state-of-the-art technology, but in 1939 it was outdated compared with the M163 and 160 HP/ltr. (3000 cc and 480 HP).

The power of the BRM V16 was enormous, but you will agree that nevertheless it was nearly undrivable due to the fact that power was available only at high revs and with a bang. A roots blower and somewhat less power, and it would have been a real winner.

Concerning tyres you are correct of course, the problems rise with the weight, but I believe the topic was not the load force, but the centrifugal force.

The location problem was a timing problem, and consequently a speed problem. Sounds confusing, but one has to consider the given facts. The target for 1936/37 was 500 km/h, but must be increased for 1938 to 550 km/h, and for 1939/40 even to 600 km/h. Already in 1936 it was obvious that the Frankfurt-Darmstadt autobahn was unsuitable for higher speeds, so the special autobahn stretch at Dessau was projected. However, this was only finished early 1939, and additionally it was shorter than projected. During construction a large lignite deposit was detected under the projected part, and given the specific situation of Germany in that period energy was more important than speed records. So the autobahn had to make a deviation, meaning a bend and consequent shortcut of the planned high-speed stretch. However, calculations confirmed that the remaining track was still sufficient for the T80. So, if Dessau had been available as early as 1936 or 37, a DAB twin-engined W125 would have been worth the idea to top 500 km/h, but when the track was ready, the new target stood at 600 km/h.

Anyhow, it is really a pity that we had never the chance to compare the T80 and the Railton in action. Size, weight, and power had been more or less identical, but the T80 had a considerable smaller front surface and lower drag coefficient, so my bet is the T80 ....!



[This message has been edited by Michael M (edited 05-04-2000).]

[Ray Bell]

And traction control to help it get speed up faster!

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Life and love are mixed with pain...

[Roger Clark]

Michael,
Thanks for the drawing. I've always liked the big aero engines, though I don't know much about them. I remember a description of the Napier Sabre engine on test. It was an H24 of well over 20 litres but it was being taken up and down the rev range like a 3 litre racing engine.

Years ago I read a book called "The Power to Fly" by Leonard Setright about the history piston aero engines but I believe it's long ago out of print.

I think you are a little unfair on the Mercedes Straight 8 engines. You would expect an engine designed for an umlimited capacity formula to be defficient in BHP/litre. BHP/sq inch of piston area is a better comparison, and on this basis the M125 (7.52) did better than the M163 (7.4. The 1936 version of the M25 would have been slightly worse. I don't have figures for the DAB.

Your right about the shourtcomings of the V16 BRM but the thought of that car with a sensible supercharger is like learning that your old girlfriend has taken up knitting.

[Ray Bell]

If you want to look at aero engines, and get some Setright knowledge, blast your brain with the first post in 'Other Oddball Engines' thread in the Technical forum. It's a doosy. There's more in that thread and in another similar thread... they were broken up because the cutaways and GIFs took too long do download.

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Life and love are mixed with pain...

[Roger Clark]

Thanks, Ray. I don't often get a chance to look at the Technical Forum because of the time this one, and the subsequent "research", takes. That Nomad would make a nice little engine for a Grand Prix car!