203 replies to this topic

[Stefan Roess]

https://www.traumauto.../html/6097.html

Quote

GERMAN:
Um die Wirkung der beileibe nicht überzeugenden Bremsen beim 300 SLR zu verbessern, kamen die Techniker bei Daimler-Benz auf eine sehr spezielle Lösung: Beim 24 Stunden-Rennen in Le Mans präsentierte man die hydraulische Luftbremse! Dabei handelte es sich um eine 0,7 Quadratmeter große Klappe hinter den Sitzen, die - am Heckteil des Rahmens befestigt - hydraulisch beim Bremsen aufgestellt wurde. Diese Klappe allein erlaubte eine Verzögerung von 3 m/s². Angenehmer Nebeneffekt war eine stabilisierende Wirkung des Hinterwagens beim Bremsen durch den erzeugten Abtrieb.

Quote

ENGLISH (Google translation):
In order to improve the effect of the brakes that are not convincing at the 300 SLR, the technicians at Daimler-Benz came up with a very special solution: the 24-hour race in Le Mans presented the hydraulic airbrake! This was a 0.7-square-meter flap behind the seats, mounted on the rear of the frame, hydraulically when braking. This flap alone allowed a delay of 3 m / s². A pleasant side effect was a stabilizing effect of the rear car when braking by the generated output.

[Stefan Roess]

https://blog.mercedes...0-slr-von-1955/

Quote

GERMAN:
In Le Mans machen die silbernen Zweisitzer später zunächst Furore mit unkonventionellen Bremshilfen. Zum einen lässt sich mit Hilfe von vier Knöpfen ein Schuss Öl in die jeweilige Bremstrommel sprühen, wenn ein Rad blockiert, was damals bei Fahrzeugen aller Marken verhältnismäßig oft passiert. Zum anderen reckt sich, vom Fahrer per Hand aktiviert, bei Bedarf am Fahrzeugheck eine zusätzliche Luftbremse in den Fahrtwind. Die Wirkung ist beachtlich: Er sei wie von einem Gummiseil zurückgehalten worden, erinnert sich John Fitch. Und: Bevor sie beim Herausbeschleunigen aus einer Kurve ganz in ihre Ruhestellung zurückgekehrt sei, habe sie die Traktion deutlich verbessert, merkt Moss an.

Quote

ENGLISH (Google translation):
In Le Mans, the silver Zweisitzer [double seater] later caused a sensation with unconventional braking aids. On the one hand, a shot of oil can be sprayed into the respective brake drum by means of four buttons if a wheel blocks, which then happens relatively frequently in vehicles of all brands. On the other hand, when activated by the driver by hand, an additional airbrake can be applied to the vehicle winch, if required, at the vehicle tailgate. The effect is remarkable: he was held back as if by a rubber rope, remembers John Fitch. And, before returning to the rest position, she had significantly improved the traction, as Moss explained.

-> also some interesting info here, that wheels blocked relatively frequently of all brands

[Stefan Roess]

Well not really new info here.
Still leaves the question open how strong was the fading?

Quote

GERMAN:
Buch "Ein Jahrhundert Automobiltechnik: Personenwagen" (1986)
... Aufsehen erregte der Jaguar-Sieg im 24-Stunden-Rennen von Le Mans 1953, errungen mit Girling-Teilbelag-Scheibenbremsen nach Dunlop-Lizenz. Die Piloten konnten die Kurven schneller anfahren, weil sie mit den wirksameren und fading-unempfindlichen Scheibenbremsen erst später zu bremsen brauchten als die Konkurrenten mit Trommelbremsen. Der Jaguar-Sieg verhalf der Scheibenbremse nach Jahrzehnten halbherziger Bemühungen der Bremsen- und Autofirmen zum Durchbruch im Renn- und später Personenwagenbau.

Quote

ENGLISH (Google translation):
Book "A Century Automobile Technology: Passenger Cars" (1986)
... The Jaguar victory in the Le Mans 24-hour race in 1953 attracted attention, with Girling part-plate disc brakes after Dunlop license. The pilots were able to accelerate the corners faster, because they only had to brake later with the more effective and fading-insensitive disc brakes than the competitors with drum brakes. The Jaguar victory helped the disc brake to breakthrough in racing and later passenger car construction after decades of half-hearted efforts by the brake and car companies.

Attached Files

•  Book Ein Jahrhundert Automobiltechnik Personenwagen - cover.jpg   350.79K   10 downloads
•  Book Ein Jahrhundert Automobiltechnik Personenwagen - brake fading.jpg   136.7K   11 downloads

[Alan Davies]

I still say that the green indicator is misleading after a few laps, encouraging you to attempt a pass into a braking area thinking you have cool brakes only to find that the merest touch of the brakes turns the indicator immediately red causing a crash.  Green should mean cool.  I appreciate that in life the brakes will remain heated so the indicator should stay yellow.  
What do you say?

[gliebzeit]

The bottom line is that you must change your way of driving .... drastically ...as if you've never driven a simulated 1967 F1 car.

Attached Files

•  Taruffi book excerpt.jpg   388.52K   31 downloads

[Border Reiver]

Alan Davies, on May 12 2017 - 04:12 AM, said:

I still say that the green indicator is misleading after a few laps, encouraging you to attempt a pass into a braking area thinking you have cool brakes only to find that the merest touch of the brakes turns the indicator immediately red causing a crash.  Green should mean cool.  I appreciate that in life the brakes will remain heated so the indicator should stay yellow.  
What do you say?

I think there is a misconception about what the colours indicate. Green shows that the brakes are currently colder than the temperature where they start to fade. It does not mean that the brakes are cold or that as soon as you touch them that they won't immediately return to yellow. Yellow indicates that the brakes are in the temperature range where they are starting to fade and so for full pedal deflection you will not longer get full pedal effect. Red indicates that the brakes are now fully faded and are only giving their minimum braking effect which I believe is equivalent to being 50% as effective as when they are totally cold.

The lights are to show which region you are in and what to expect when you start to press the pedal. This is linked to temperature but this is a non-linear scale. However, they can also be used helpfully to see when they change from one colour to the next. One way to think of the brakes is that you have a certain budget available per lap of how much they can be used and so the goal is to find a pace where every time you pass some point on each lap you have the brakes in the same state. This means that you will not become "overdrawn" and so stuck with red brakes. If you notice that lap after lap the light is changing from yellow to back green further and further along a straight then you are heading into braking debt and so you need to find a way to use the brakes less, probably by using more lift and coast and engine braking as per the description that Greg posted. If you only had a green light when the brakes were very cold, firstly you wouldn't know when the brakes were first starting to fade and giving reduced performance, but also you'd only ever see yellow or red lights after a couple of laps and so actually they would be less useful to work out your brake use budget. It is actually a pretty handy gizmo and worth keeping an eye on to see when the colour changes. If the green light has been on for a complete straight for instance, it should be pretty obvious you'll have a lot more braking capacity available than if it only flicked back to green 100 yards before you next stand on the brakes again.

Obviously in the actual car you would have a lot more feel of the resistance in the brake pedal changing to get this feedback so the light is a sort of best compromise to give the driver at least some indication of this feedback.

Rob

Edited by Border Reiver, May 12 2017 - 10:15 AM.

[gliebzeit]

[Gartner]

[Paddy the Irishman]

I hate having to keep on harping about brake fade because the 1955 mod is a most fantastic achievement and is wonderful to ‘drive’. When one reckons the man (person)-hours and varied skills that have been put into it my mind boggles. The historical research; the artistic skill; the technical skill; the testing etc; etc; etc….. Thank you very much team, it is just wonderful and I will continue to be delighted and astonished with the mod

But - Steffan, thank you for the references to braking on the Mercedes Le Mans cars, while there are many parallels those cars are not identical to the 196.
The Le Mans cars were heavier. Denis Jenkinson in’ Profile Publication #54’ (Ref 1) quotes 830kg for 300SLR; Michael Riedner in ‘Mercedes 196-The Last of the Silver Arrows’ (Ref 2 p 322) quotes 650kg for 196, 700kg for streamliner; [This does seem a very large difference, but when (Ref 2 p 124) tells us the relocation of the front brakes, inboard to outboard, alone saved 40kgs it begins to make sense].
Their engines had different power outputs 300SLR 3 litre @ 300bhp (ref 1) and 196 2.5 litre @ 260PS (R ysef 2), The SLRs were running for a considerably greater distance than a GP, about 8 times as far at Le Mans, 2 ½ times the Mille Miglia, so combating any ‘fade’ and lining wear would have been a greater need. If Mercedes had found the need for ‘air brakes’ on the GP cars they would surely have fitted them. Top speeds of the two cars were more or less the same the 300SLR reaching 187mph twice in the Mille Miglia (ref 1) The GP cars averaged 213.5kmh around Avus for 504 km in the Berlin GP in 1954, while not running flat out (Ref 1 p210)

Ref 2 p129- “In braking from 300kmh the temperatures of the drums rose by 150degrees C, at an ambient temperature [Would this be the ’running temperature’ of the brake drums ?] of 80 C, the final max values were 230 (inboard) and 275 (outboard). Even under conditions of constant harsh braking, the heat was dissipated rapidly thanks to the ventilation. The result was very low wear on the brake linings. 1955 saw the addition of a brake servo”.



[I do not think this implies that at these temperatures braking is very badly affected, but in fact were in accordance with design calculations, which would NOT have been planning for ultimate failure ]




As against all that an Article in “Supercar Classics” December 1988, “Fangio’s Powerbase” by Mark Gillies, describing having driven the W196 [fitted with the 3 litre engine and with the inboard brakes] on track for 100 miles says, - “ The only flaw is the braking. Tramp hard on the centre pedal and nothing happens for the first 50 yards, which is alarming when you’re hauling yourself down from close on 100mph for a tight hairpin. Eventually they start working, accompanied by the nauseous smell of burning Ferodo as it wafts into the cockpit while the front wheels weave gently as the shoes start to bite. The seeming shortage of brakes result from the fact that you’re entering corners so quickly, but even so they’re not as good as the 250F’s - by a long way.”
-- ‘Purple prose’ in places including that Mercedes ran ‘Textar’ brake material and not ‘Ferodo’ but other references do say that braking in those cars required up to 200lbs foot pressure on the pedal.


I think that it can be agreed that the braking performance would have been more or less the same on all cars but I still feel that the deterioration in the mod is too swift, Taruffi’s book, which you excerpt, is apposite, but remember that his car-driving career commenced in 1932 and this was advice for drivers in all areas and not just for drivers of those cars supposed to be at the peak of racing. For example Standard Jaguar XK120s were prone to brake fade when used in racing if not treated with great care, but Mercedes designed for GP racing ….?.

I still contend what I wrote in post 23 - the brake deterioration seems way too fast. At Aintree, even with the 'disc-braked' Vanwall, the brakes will go to red well before the end of an initial standing start lap. [Best (non-Standing start) lap 2.21 so I am not going very fast]. Another test, straight out of the pits, braking in 'normal' fashion saw me "in the red" by the Melling Crossing and staying that way for the rest of a very careful 2.38 lap. I have checked that my brake is fully off at calibration and my foot is well clear when driving. Further checking on the Mercedes show somewhat similar results (faster laptime though ).



HOWEVER THE MOD IS THE MOST ENORMOUS FUN and I am going to stop writing and continue driving, compensating my braking distances and character in accordance with the colours in my tach. Thanks again to the wonderful mod team


　
　
　Please excuse the change in type size I have tried but can't correct it
　
　
　

Edited by Paddy the Irishman, May 13 2017 - 03:47 AM.

[Michkov]

Bug
Locked wheels increase brake temperatures

Expected behaviour
When a wheel is locked during braking, that brakes temperature should not increase.

How to reproduce
Find a fast track with wide flat grass runoff (I recommend Bloodbath). Accelerate to terminal velocity, move onto grass. Stand on the brakes, locking all four wheels; keep sliding. Before the wheels will start to rotated again, the brake thermometer will be red.

Notes
Tried the experiment with both the Merc SL & D50. Should really try the Vanwall, but hadn't thought of it until now.
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Bug
Shift-R leaves brakes hot

Expected behaviour
Cold brakes

How to reproduce
Shift-R any car with red brakes

Notes
Could be just a programming limitation or intentional. I'm mentioning it because it goes against 17 years of experiencing a cold car after a Shift-R
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
Minor ramblings
Because someone mentioned it above, or in some other 55 thread. The suspension seems fragile, I think I bend a front linkage by going into a gravel trap. Maybe I hit something, so regard this as an anecdote.

[Michkov]

Alan Davies, on May 12 2017 - 04:12 AM, said:

I still say that the green indicator is misleading after a few laps, encouraging you to attempt a pass into a braking area thinking you have cool brakes only to find that the merest touch of the brakes turns the indicator immediately red causing a crash.  Green should mean cool.  I appreciate that in life the brakes will remain heated so the indicator should stay yellow.  
What do you say?

I feel that relying too much on what the light says is the wrong way of taking on the brake fade. Like tyre temps you are going to reach a steady state at some point, granted it takes longer but its the same method. Get the brakes to temperature and you'll get more predictable braking. It's still the worst braking ever if you ask for two hard braking events in short succession but at least you should expect the second one to have the braking effect of an oiled elephant on ice.

Like Rob said, use the thermometer as a rough estimate where your average brake temps tend to not the concrete braking performance you can ask from them.

[Lee200]

Michov, thanks for the tests, but those "bugs" were known before the mod was released.

Yes, the brake temperature continues to increase with locked brakes because the car's speed is used as a substitute for each wheel's rotation speed.  For simplicity, the brake fade patch does not compute each wheel's brake temperature based on how fast the wheel is rotating.  While not entirely realistic, it was done this way to simplify and speed up the patch which was already extremely complex.

The brake temperature is not reset with a ShiftR.  This could have been done, but the mod team's decision was not to do so as it rewards a player that uses ShiftR.  My personal view is that Papy should not have reset the tire temps with a ShiftR either.  If and when we have a '30s era mod when tire changes were necessary, then ShiftR tire temperature resets probably won't be allowed unless the player is making a pit stop.

I made the patch, but not the settings that the patch uses.  I don't plan on ever changing the patch itself and after four years of working on this beast have moved on to other projects.  So don't count on these "bugs" ever being fixed.

I won't comment on complaints from others about how much the brakes heat and cool other than to say it was a collective decision made by the mod team.  Again, don't expect this to change.  There will be a mod update that fixes a few graphics issues though.

My suggestion to all is to just enjoy the mod physics the way it is now.  

Edited by Lee200, May 12 2017 - 03:59 PM.

[gliebzeit]

[Iestyn16]

Border Reiver, on May 12 2017 - 10:08 AM, said:

Red indicates that the brakes are now fully faded and are only giving their minimum braking effect which I believe is equivalent to being 50% as effective as when they are totally cold.

To add to this, I think the final mod release came with red at 1/3rd braking, yellow you can probably imagine as 2/3rds. For those outside of the mod team, there were 5 final variations at least that were tested.

I think a lot of the confusion about this could be made clearer if those who can't grasp the driving style (I say that afraid of the fact that some of you were driving in this era!) could say where and how much they are using the brakes.

For example - try a lap at Buenos Aires only using the brakes in T1, T3 and the final corner and report back. Doing this in the w196, I can get 1:41.5, with extra taps of the brake in e.g. the penultimate chicane if you carry too much speed in as well (same for other corners, but this should be minimised to keep enough brakes for the final corner).

PS. My dad used to have a lot of old MGs, one of each type going back to the war. My first memory of being in a car is being in one painted orange and black . Sadly I never got to drive it, it would surely be my road car today if it was so.

[Bruce]

Stefan, thanks for all the references regarding your research....most appreciated and I can see that you have put a LOT of  work into trying to achieve a simulation of the real-life physics regarding the brakes.
However (or BUT! ), to my mind it is exaggerated and could be lessened.
It has taken a lot of fun out of the '55's for me and, as a result, I have stopped using them for now.

Edited by Bruce, May 13 2017 - 06:07 AM.