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Some Technical Notes: Tyres, Engines, Whatever.

Technical Notes Tyres Tires Engines Classic

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#1 Lord

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Posted Sep 25 2018 - 02:14 PM

Hi chaps:

I'm pretty sure that almost everyone of you knows the amount of work that is required to make a good quality mod: the very existence of this platform is in itself a proof of that.
The very issue of making such mods is the amount of research one (or a team) must do in order to give the best possible quality in the final product: we all know that perfect realism is impossible - whoever says the opposite is a madman and shouldn't be trusted - but we work and toil to have at least the best apporximation that we're able to do.

So, the idea of this thread is to collect the various notes, scripts, references and such that could be useful to any future modder, in order to make the research a little bit easier. Everyone can contribute, obviously: the more the info, the better it will be.

As far as I've worked out, most of the info I got comes from Costin, Berthon, Nye, Forghieri and Benzing.

//-----------------------------------------------------------------------------//

I) TYRES


This is specifically about the size and slip angles, more than anything: as reported by https://en.wikipedia.../wiki/Tire_code in "Historical Tyre Codes" (and as confirmed by Costin's "Racing & Sports Car Chassis Design"), tyres pre-1965 were made with a fixed 90% ratio: this allowed to write them as rim diameter by widest part of the tyre, for example 7,00"x16.
From the same source, tyre pressure followed this kind of range:

- Normal: 25-30 psi
- Fast circuits: 40-45 psi
- Heavy cars (Le Mans, for example) : 60+ psi
- Raining: -10% to -15% normal pressure.

According to Berthon, Nye and Benzing (especially the latter in his "Dall'Aerodinamica alla potenza in Formula 1"), Cross-Ply tyres had from 10° to 15° of slip angle, depending on how tight was the steel frame inside the rubber.




II) SUSPENSIONS

Even in the 1960's the suspension stiffness didn't change much since the very early '30s: according to Costin, one should've always looked for 70 cycles per minute in front and 80 in the rear, but this often proved difficult to achieve because of the steel used, what was then-called EN45A: the modern equivalent is the AISI 9260. Always according to Costin and Forghieri, at the time they used to calculate the stiffness of the suspensions by using an equivalent semi-cantilever leaf spring (a leaf spring that is free to swing at just one of the edges) and usually they counted a leaf thickness of half a centimeter. This explains why the cars were often very soft when compared to modern solutions.

When designing them, the designer had to account 3.5 inches of bump and maximum 3 inches of droop.

Castor/Caster usually is between 3° to 8°.

Braking ratios should go from around (Rear:Front) 40%:60% in a front-engined car to a 45:55 on a mid-engined one.



III) WEIGHT

According to Costin and Benzing, in order to have a good road-holding the car's weight distibution with no driver and all fluids (full fuel included) must aim for a 45% front and 55% rear, give or take a 5% more on the rear.




IV) ENGINES

About the eternal dispute between Italian horsepower and DIN/HP horsepower: before the introduction of the Kilowatt (1978) the CUNA (Commissione tecnica UNificazione dell' Autoveicolo, http://www.cuna-tech...strastoria.html ) used a measuring system that was even more barebones than the SAE Gross: the SAE Gross method measures the car with only the stuff it requires to actually run (so no filters and such), while the CUNA system allowed the engine to be measured without almost anything deemed useless like exhaust pipes, filters, radiator fans, dynamos... this allowed for a 15% power increase than the DIN standard and a 5% increase on the SAE Gross.

Edited by Lord, Sep 25 2018 - 02:24 PM.


#2 Iestyn16

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Posted Sep 25 2018 - 04:35 PM

Interesting post, Lord. He might be 86, but Enrico Benzing still updates his website after every race! http://www.formula1benzing.eu/

He says in particular that they are exceeding the maximum fuel flow in F1 and now reaching over 1,100 hp! So, it would be very interesting to read his writing about the GPL era.

In terms of original GPL cars, only the Brabham and Cooper fall under that weight distribution, with the other five being too rearwards (over 60%).

#3 Lord

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Posted Sep 26 2018 - 02:11 AM

View PostIestyn16, on Sep 25 2018 - 04:35 PM, said:

Interesting post, Lord. He might be 86, but Enrico Benzing still updates his website after every race! http://www.formula1benzing.eu/

He says in particular that they are exceeding the maximum fuel flow in F1 and now reaching over 1,100 hp! So, it would be very interesting to read his writing about the GPL era.

In terms of original GPL cars, only the Brabham and Cooper fall under that weight distribution, with the other five being too rearwards (over 60%).

When you love your work, you'll be working gladly until you're dead ;)

About the weight distribution, are we counting with or without a full tank of fuel?

#4 John Woods

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Posted Sep 26 2018 - 07:20 AM

Good idea Lord.
More is better.

Pirelli History of Tires

In Italian


Lately of the opinion tire design and innovation really is the critical technical history of racing.



:D

#5 Lord

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Posted Sep 26 2018 - 11:08 AM

View PostJohn Woods, on Sep 26 2018 - 07:20 AM, said:

Good idea Lord.
More is better.

Pirelli History of Tires

In Italian


Lately of the opinion tire design and innovation really is the critical technical history of racing.



:D

Thanks John, great finding there :D





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