F1technical.net

Hey all,


The F1 rules specify bodywork locations relative to a reference plane.

Where is this reference plane! It's nowhere in the rules!!!

I think this is an excellent question. It's not in the definitions. You only have this as an approximate definition:

3.12 Bodywork facing the ground:
3.12.1 All sprung parts of the car situated more than 330mm behind the front wheel centre line and more than 330mm forward of the rear wheel centre line, and which are visible from underneath, must form surfaces which lie on one of two parallel planes, the reference plane or the step plane.

So, my interpretation is that the reference plane is the lower plane of the car facing the ground, which, by 3.12.1 must be a flat surface.

My interpretation is that the reference plane is the surface that the plank is attatched to.

So for example the underside of the plank is -10mm.


I think!!!

Edit: I have just looked at the technical regulations drawings.

If you look at drawing 2A, it explains it without doubt.

The lower suface of the step plane is the reference plane.

My unsderstanding is that it's the plane that is 50mm above the lower section of the floor, essentially the bottoms of the sidepods. My understanding is that all demensions are based off that surface.

The reference plane is indeed the part of the floor, that the planks attached to, i.e lowest part of the car (plank excluded). this is the part of the of the car that is used as a datum for all other measurements.
the upper section of floor flanking the central reference plane os the "step" plane.

There is an in depth analysis here:

http://www.cliptheapex.com/forum/viewto ... f=7&t=2121

Ciro Pabón wrote:I think this is an excellent question. It's not in the definitions. You only have this as an approximate definition:
...

I think Drawing 7, page 63 of 63, in the FIA Technical regulations makes it crystal-clear.

maybe a picture (or two) says more then words


http://i805.photobucket.com/albums/yy33 ... eplane.jpg


http://i805.photobucket.com/albums/yy33 ... plane1.jpg

To be technical about it ….ok, I admit this is pedantic …

The reference plane is not the floor, it is an arbitrary datum used for defining vertical dimensions of the car. Furthermore, there is no definition because it is impossible to define an arbitrary zero point.

However for simplicity, the rules locate the underside of the floor at the reference plane. This means the FIA scrutineers can sit the car flat on an inspection table (without the plank) and use the table surface as the datum to measure the height of the bodywork.

As a bit of background, it is not possible to measure height of bodywork from the ground because the cars move up and down with the varying suspension settings, tyre pressures and weight. You can’t even define the floor as horizontal because the car slopes (the rear is usually slightly higher than the front). Hence the simplicity of using an arbitrary plane independent of the ground in both height and slope.

xpensive - drawing 7 is on page 67 of 67 in my copy of the technical regulations, dated 23rd June 2010. What date is your copy? I wonder what was added to generate 4 extra pages?

August 19th, 2009, Richard. I will check out the new download.

the main point of interst here is:
Although the bottom of the car and the reference plane are drawn up as the same in the pics they are NOT in reality as the floor has considerable tolerance allowance in height e.g +/-5mm as a manufacturing tolerance..so effectively you could use a full 10mm of rake,curve, slope ,or kink still complying to the rules.You just need to put the reference plane were you need it really and work from there .Of course once you have decided just wher you position the referenc plane this will determine the step plane which is also allowed to have +/-5mm leeway for any measurement be taken from there. ...so in effect the whole regs open out the possibility to bottom and stepbottom not paralell at all...

This opens the posibility to rise the plank covered bottom a bit at the front and opens the possibility to design some rake into the stepbottom as well all fully legal. giving you 10 mm more rake and possibly downforce ..maybe a route that RB is pursueing...

I think this is why the rules say, the lowest point of the floor/part which holds the plank.
So if you lower your car, onto the "set up/scrutineering table" you may touch with your two lowest points (in longitudinal direction), this defines the reference plane for your car then, and all dimensions is relation to it, need to comply with the rules.
But I would agree, that the reference plane, due to the allowed tolerences you mention, from car to car can be slightly different to the ground plane.

scarbs wrote:The reference plane is indeed the part of the floor, that the planks attached to, i.e lowest part of the car (plank excluded). this is the part of the of the car that is used as a datum for all other measurements.
the upper section of floor flanking the central reference plane os the "step" plane.

so if i understood you correctly the step plane lays above the reference plane?

747heavy wrote:I think this is why the rules say, the lowest point of the floor/part which holds the plank.
So if you lower your car, onto the "set up/scrutineering table" you may touch with your two lowest points (in longitudinal direction), this defines the reference plane for your car then, and all dimensions is relation to it, need to comply with the rules.
But I would agree, that the reference plane, due to the allowed tolerences you mention, from car to car can be slightly different to the ground plane.

ermmm.just can´t find this piece ..would you please give a reference?
looking up the regs again it seems al measurement is taken in relation to the reference plane so the lleway is not 20 but just 10mm ,youre not allowed to add up the tolerances there.Of course the rule says :for manufacturing inaccuracies...so you need precise imprecision there..

marcush. wrote:the main point of interst here is:
Although the bottom of the car and the reference plane are drawn up as the same in the pics they are NOT in reality as the floor has considerable tolerance allowance in height e.g +/-5mm as a manufacturing tolerance..so effectively you could use a full 10mm of rake,curve, slope ,or kink still complying to the rules.You just need to put the reference plane were you need it really and work from there .Of course once you have decided just wher you position the referenc plane this will determine the step plane which is also allowed to have +/-5mm leeway for any measurement be taken from there. ...so in effect the whole regs open out the possibility to bottom and stepbottom not paralell at all...

This opens the posibility to rise the plank covered bottom a bit at the front and opens the possibility to design some rake into the stepbottom as well all fully legal. giving you 10 mm more rake and possibly downforce ..maybe a route that RB is pursueing...

Sorry MArcus, don´t follow you here.

Do you mean "open up" or " rule out" ??
"Open out" is a very specific term

However. the rules clearly state, that the "Step plane" has to be parallel to the "Reference plane".

3.12 Bodywork facing the ground :
3.12.1 All sprung parts of the car situated from 330mm behind the front wheel centre line to the rear wheel centre line, and which are visible from underneath, must form surfaces which lie on one of two parallel planes, the reference plane or the step plane.

and I think, here it allows for your said production tolerances, but at the same time rules out any too "smart" interpretation of the rules:

3.12.6 To help overcome any possible manufacturing problems, and not to permit any design which may contravene any part of these regulations, dimensional tolerances are permitted on bodywork situated between a point lying 330mm behind the front wheel centre line and the rear wheel centre line. A vertical tolerance of +/- 5mm is permissible across the surfaces lying on the reference and step planes and a horizontal tolerance of 5mm is permitted when assessing whether a surface is visible from beneath the car.