Again, thanks to my friend for this article below…:
There has been a lot of discussion going on in various websites and forums about our proposed system, over the last couple of days. Sadly, most of this discussion has revolved around its legality and/or the impact of Mercury on the environment, rather than its merits and the technical reasons behind it.
We will leave it to the self-proclaimed “experts” on the different forums to argue about its legality, as we trust that finally the real experts (i.e. the FIA) will decide if it’s legal or not. Just an interesting observation. ScarbsF1’s report on the new McLaren MP4-27 mentions that he asked Paddy Lowe regarding the Lotus anti-dive brake system and he said that the team looked into it but dismissed it immediately because the engineers felt that it was illegal. However, when ScarbsF1 inquired with regards to interlinked systems, the team refused to comment…
Enough with that. In the meantime, we will try to explain over the next couple of days, to the few fans with an interest in the technical aspects of the sport, the idea behind the system, and more specifically:
1. Why it is not just another” interconnected /hydro-elastic suspension” – as some like to claim,
2. Why it is not “enough” to just “lock out” the front suspension under braking, and
3. Which specific characteristics of an F1 car, have been leading to the development of the Lotus –Renault “reactive ride height” system [now banned by the FIA] and our proposed system.
In order to do so, let´s first take a look at a “generic” F1 car according to the 2011 rules.
First, we will define, which loads we have in a hard braking manoeuver at top speed [5G deceleration] and we will later show what this means to the front ride height [front wing height over the ground] of the car.
We will show all the maths [no panic – it´s simple], and we will make some assumptions along the way. Now as is the case with every assumption, we can make some “wrong” assumptions, but this will not take away from the general principle or overall concept, nor will it render the final conclusion void. So, if you feel we have made some wrong (or inaccurate) assumptions in terms of overall downforce levels, centre of gravity [CoG] height, % of front downforce or tyre stiffness, we encourage you to do the calculations based on your own numbers, and to see what the end result looks like. We are confident, that it will not be night and day different from our final values.
So let´s look at some numbers:
To comply with the 2011 rules, a Formula 1 car must have a minimum weight of 640 kg including the driver. To complete a race distance of approximately 300 km without refueling, the car will need an estimated 160 kg of fuel. The weight distribution between the front and the rear axle is set by the rules to 45.5-46.7% front and 53.3-54.5% rear and we assume a maximum downforce value of 15000 N [1523 kgf] and a distribution of 43% at the front axle [feel free to use your own values here].
Therefore the fuel load changes the total weight of the car by approximately 25% between Qualifying and the start of the race. This in itself is already a great challenge when it comes to choosing the appropriate setup for the car. On top of this, the amount of downforce generated by current Formula 1 cars will change the load at the wheels by about 300% at the front and about 322% at the rear. For the suspension and the tyres, the car appears to be three times as heavy at high speeds, than it is at low speeds. Combine this 300% increase in vertical load with the very low ground clearance of a Formula 1 car, and you start to see, where the challenge for the race engineers lies. The lower the car can run to the ground, the more downforce it will produce, as long as a minimum clearance is maintained, and the skid block/plank does not get excessively worn.
During braking, load will be transferred from the rear axle to the front axle; the underlying calculation for the load transfer is:
Total load transfer = (total weight of the car x longitudinal acceleration x CoG height) / wheelbase
We use a car with a ½ full tank as basis for our calculations. Please see the graphics below for the results.
As you can see, from the calculations above, the weight on the front axle increases by +267 kg and decreases by -267 kg at the rear axles during the 5G braking maneuver in our example. What this means to our front ride height and front wing and splitter (tea-tray) height, we will explain in the next blog entry.