64 replies to this topic

[Formula-1]

Never knew what it's for.

[fuzzybunny]

Ok, it all started when Max Mosley's german timber company found the market had dropped to substantially under their capability to supply.
He needed a new market and fast.
The original proposals (wooden grooved tyres and then later mandatory on-board oars for wet races) were mooted by the council, so he proposed replacing the previous titanium(?) skid block with wood, along with the customary thin excuse. These pine planks could be sold to teams at a low cost of $148 000 each and would be ground to sawdust each race, thereby having to be replaced. Voila, a sustainable market.

Either that or it could be some sort of technical reason which I'm sure someone clever will explain to us...

[Riker!]

Isnt it to stop cars from bottoming out, instead of using metal (dangers with sparks maybe?) they chose wood........... in otherwords BEATS THE **** OUTTA ME KEMOSABE.

[A3]

fuzzybunny

Edit: Should rephrase that: The wooden plank is there to control ride height. If the plank wears too much, it means the car is running too low.

[Moanaman]

Originally posted by Riker!
in otherwords BEATS THE **** OUTTA ME KEMOSABE.

[Engineguy]

The wood used is usually jabrock, used because it's very tough and a thin (8mm?) piece will last through a race. It is not used to "control" ride height but as a sacrificial element to protect the carbon fiber tub from the inevitable bottoming on full tanks, in abrupt dips, etc.. Even with F1 budgets nobody is silly enough to allow the tub to get damaged by scraping... besides the cost, there are safety and changing torsional stiffness issues.

Until it was banned, titanium was all the rage in F1 for a couple of years (late '80s?) and made for spectacular roostertails of sparks under high speed brake application (at end of straight, speed is highest... therefore downforce is greatest, car at its lowest) for the first few laps with full fuel.

[baddog]

Originally posted by Engineguy
The wood used is usually jabrock, used because it's very tough and a thin (8mm?) piece will last through a race. It is not used to "control" ride height but as a sacrificial element to protect the carbon fiber tub from the inevitable bottoming on full tanks, in abrupt dips, etc.. Even with F1 budgets nobody is silly enough to allow the tub to get damaged by scraping... besides the cost, there are safety and changing torsional stiffness issues.

unfortunately you are entirely wrong. The plank IS used to force the teams to maintain a ride height. It IS checked after the race and if more than a specified amount was missing the car would be (and has been on more than one occasion) disqualified.

No team would ever ruin their undercar aero with such a thing.

Shaun

[daSilvium]

Yes it's 10mm thick i think and if more than 1mm is worn away across half or 3/4ers of the width of it, then the car will be fail post-race scrutineering.

Schumacher has been disqualified before for having the plank too worn.

It's nothing to do with protecting the bottom of the car - it's a ride height thing.

[Ruud de la Rosa]

Originally posted by Engineguy
The wood used is usually jabrock, used because it's very tough and a thin (8mm?) piece will last through a race. It is not used to "control" ride height but as a sacrificial element to protect the carbon fiber tub from the inevitable bottoming on full tanks, in abrupt dips, etc.. Even with F1 budgets nobody is silly enough to allow the tub to get damaged by scraping... besides the cost, there are safety and changing torsional stiffness issues.

Until it was banned, titanium was all the rage in F1 for a couple of years (late '80s?) and made for spectacular roostertails of sparks under high speed brake application (at end of straight, speed is highest... therefore downforce is greatest, car at its lowest) for the first few laps with full fuel.

Actually it is to control ride heights, if it wears to much (10mm?) you get dqed. From FIA.com

3.13 Skid block :
3.13.1 Beneath the surface formed by all parts lying on the reference plane, a rectangular skid block, with a
50mm radius (+/-2mm) on each front corner, must be fitted. This skid block may comprise more than one
piece but must :
a) extend longitudinally from a point lying 330mm behind the front wheel centre line to the centre line
of the rear wheels.
b) be made from an homogeneous material with a specific gravity between 1.3 and 1.45.
c) have a width of 300mm with a tolerance of +/- 2mm.
d) have a thickness of 10mm with a tolerance of +/- 1mm.
e) have a uniform thickness when new.
f) have no holes or cut outs other than those necessary to fit the fasteners permitted by 3.13.2 or those
holes specifically mentioned in g) below.
g) have seven precisely placed holes the positions of which are detailed in Drawing 1. In order to
establish the conformity of the skid block after use, it's thickness will only be measured in the four
50mm diameter holes and the two forward 80mm diameter holes.
h) be fixed symmetrically about the centre line of the car in such a way that no air may pass between it
and the surface formed by the parts lying on the reference plane.

Seealso picture http://www.fia.com/r...sins-2002-a.pdf (first one is the skidblock)

Ruudje

[A3]

Originally posted by Engineguy
... therefore downforce is greatest, car at its lowest) for the first few laps with full fuel.

A lighter car would go faster, therefor downforce would increase, no?


Great shot of Irvine's Jaguar bottoming out in Eau Rouge:
http://208.50.7.92/f...um/wp-10-hi.jpg

[Ali_G]

A3: Nope. A heavier car always has more grip than a lighter car. But a heavier car has more centrafugal force to deal with when going around corners hence a lighter car will corner faster.

The plank was put in place to do 2 things.

1. Maintain a decent ride heiht.
2. Make crap of the underfloor aerodynamics. Before insisting on the plank, every F1 car had a flat bottom. This stepped bottom approach lessens the downforce even more. I'm not sure but I think it was introduced after Imola 94 at either Spain or France. Can't remember.

Niall

[A3]

Originally posted by Ali_G
A3: Nope. A heavier car always has more grip than a lighter car.

Not talking about grip, but about downforce (straight line). Engineguy said that downforce would be greatest if it has a lot of fuel on board. But lose fuel and you gain top speed, so downforce improves.

[Gemini]

Originally posted by A3


Engineguy said that downforce would be greatest if it has a lot of fuel on board.

Not that I agree what Engineguy said about plank ,

...

but I can't see where he originally said what I quote from you above?

[fuzzybunny]

Originally posted by Ali_G
A3: Nope. A heavier car always has more grip than a lighter car.

You have figures to back that up? I'd be interested to see what they look like.
Always wondered what the speed/DF gain was from less weight.

Originally posted by Ali_G

But a heavier car has more centrafugal force to deal with when going around corners hence a lighter car will corner faster.

Centrifugal force is fictional.
The inertia increases with mass.

[A3]

Originally posted by Gemini


but I can't see where he originally said what I quote from you above?

Originally posted by Engineguy
... therefore downforce is greatest, car at its lowest) for the first few laps with full fuel.

[Gemini]

A3, why don't you quote what is in brackets, means to be read together, first:

(at end of straight, speed is highest... therefore downforce is greatest, car at its lowest)

he related downforce to speed not to weight
:

[A3]

You're right, I'm sorry. Damn, I hate monday mornings ! Where's my coffee?

[Gemini]

Originally posted by A3
Damn, I hate monday mornings !

[Ali_G]

Originally posted by fuzzybunny

You have figures to back that up? I'd be interested to see what they look like.
Always wondered what the speed/DF gain was from less weight.


Centrifugal force is fictional.
The inertia increases with mass.

?

Weight will do the same as downforce. It pushes the tyres harder into the track and hence better grip. Do you think a tractor could pull a trailer through a muddy field if it was very light ?


How in god is Centrfugal force frictional ?

Centrifugal force is the force that wants a body which is travelling in an arc to carry on straight. it is based on the principle that an object will always want to travel in a straight line. How in god is this frictional ? that makes no sense at all.

Niall

[fuzzybunny]

Originally posted by Gemini

he related downforce... ...to weight
:

Hence the problem!!!;)

Creative quoting is fun!!

With a little practice, we could go work for F1-live....

[baddog]

Originally posted by Ali_G


?

Weight will do the same as downforce. It pushes the tyres harder into the track and hence better grip. Do you think a tractor could pull a trailer through a muddy field if it was very light ?


How in god is Centrfugal force frictional ?

Centrifugal force is the force that wants a body which is travelling in an arc to carry on straight. it is based on the principle that an object will always want to travel in a straight line. How in god is this frictional ? that makes no sense at all.

Niall

in fact centripedal force is the straight-lining effect and is just inertia. centriFUGAL force is the effect seent hat leads one to imagine the object wants to go outwards from the cricle it is describing, and does not in fact exist (except in the practical 'kill you' sense of existing)

Shaun

[fuzzybunny]

Originally posted by Ali_G


?

Weight will do the same as downforce. It pushes the tyres harder into the track and hence better grip. Do you think a tractor could pull a trailer through a muddy field if it was very light ?


How in god is Centrfugal force frictional ?

Centrifugal force is the force that wants a body which is travelling in an arc to carry on straight. it is based on the principle that an object will always want to travel in a straight line. How in god is this frictional ? that makes no sense at all.

Niall

Chill, I'm not arguing your weight/speed/downforce point, I was just hoping you had some figures, cause I've always wondered what the effect would be. i.e. 1kg less weight = 4kmh more top speed at x point = x kg more downforce. Or vice versa.

I said fictional, not frictional.

[fuzzybunny]

Originally posted by baddog


in fact centripedal force is the straight-lining effect and is just inertia. centriFUGAL force is the effect seent hat leads one to imagine the object wants to go outwards from the cricle it is describing, and does not in fact exist (except in the practical 'kill you' sense of existing)

Shaun

Thanks, now I don't have to dig it up!!

[Ali_G]

Originally posted by baddog


in fact centripedal force is the straight-lining effect and is just inertia. centriFUGAL force is the effect seent hat leads one to imagine the object wants to go outwards from the cricle it is describing, and does not in fact exist (except in the practical 'kill you' sense of existing)

Shaun

Isn't Centripedal force the force that draws traveelin in an arc into the centre of the arc ?

Niall

[mikedeering]

It was introduced at Hockenheim 1994 in the wake of the carnage at Imola that year.

It's height of fame was in the aftermath of the Belgium GP of that year where Schumacher won the race (despite a mid race spin where he clattered over the kerbs) but was subsequently DQ'd as the plank was worn by more than 10mm.

Although Benetton protested and argued that the wear was due to the spin and no performance advantage was gained, the DQ stood, handing victory to Damon Hill in the Williams.

Since then, not much has been said about the plank.

As for the sparks issue - up until the end of 1987, the cars raced with titanium skid blocks on the cars that protected the underside of the car as it bottomed out - it was these which produced the fiery sparks from the cars. You watch the 1987 review tape and there are sparks all over the place - especially at a circuit such as the old Osterreichring. They were outlawed for the start of 1988 - not sure why - and with that the sparks disappeared. There are lots of brilliant photos from the likes of Paul Henri Cahier and others from this time period with F1 cars throwing up a ton of sparks.

[maclaren]

Originally posted by Engineguy
Until it was banned, titanium was all the rage in F1 for a couple of years (late '80s?) and made for spectacular roostertails of sparks under high speed brake application (at end of straight, speed is highest... therefore downforce is greatest, car at its lowest) for the first few laps with full fuel.

Actually they are riding on bumb rubbers down the straights so additional weight makes no difference.

[X-ray]

Originally posted by fuzzybunny


Chill, I'm not arguing your weight/speed/downforce point, I was just hoping you had some figures, cause I've always wondered what the effect would be. i.e. 1kg less weight = 4kmh more top speed at x point = x kg more downforce. Or vice versa.

I said fictional, not frictional.

I think it's important to add that top speed is still the same no matter the weight. Acceleration on the other hand is less the higher the weight is and vice versa. So in practice a car with a full fuel tank has a lower top speed at Les Combes for example than a light car because of less acceleration.

[Al.]

[QUOTE]Originally posted by Ali_G


Isn't Centripedal force the force that draws traveelin in an arc into the centre of the arc ?

Niall [/QUOTE]

Yes it is and as every force has an equal and opposite reaction ( some bloke called Newton ) centrifugal force is the equal and opposite reaction.

[QUOTE]Originally posted by X-ray
[B]

[QUOTE]I think it's important to add that top speed is still the same no matter the weight. Acceleration on the other hand is less the higher the weight is and vice versa. So in practice a car with a full fuel tank has a lower top speed at Les Combes for example than a light car because of less acceleration.[/QUOTE]

To recap a heavier car is able to corner at a higher speed because the weight is translated to a vertical force pushing the car to the ground, the higher the force the greater the grip, something that is taken further with aerodynamic downforce.

However X-ray hit the proverbial nail, in that more weight equals slower acceleration and I would also add harder to stop at the end of the straight.

As for the trade off, less weight almost always better. You can claw the cornering grip loss back with downforce. The cars only get anywhere near maximum downforce at Monaco.

[Locai]

A heavier car would have more grip IF it were driven in a straight-line AND if all other things were equal (tires, aero, etc.) The biggest thing you lose with a heavier car is speed.

The "wooden" planks aren't wooden anymore. They're a composite of some sort.

The purposes of the planks are to mandate a minimum ground clearance and to help prevent "ground effects" aerodynamics, such as CART and the IRL allow.

Banning "ground effects" coupled with the lightweight chassis requires that much of the downforce of the cars is supplied by the wings. The downside of this is that the cars lose so much of their downforce when they get into the "dirty air" of a car in front of them that it has made passing nearly impossible.

[daSilvium]

Originally posted by X-ray

I think it's important to add that top speed is still the same no matter the weight.

Yes, that's true IF the straight is long enough to attain the top speed of the car.

More weight equals lower acceleration (assuming the team hasn't changed the gearing of the car) and therefore at any point down a main straight, the heavier car should travelling at a slightly lower speed than a lighter car.

BUT, as you said, the heavier car will *ultimately* get to exactly the same top speed as the lighter car - it's just that it will take a little longer (a few seconds ?) to do so.
If the straight is long enough for both cars to attain max. speed, then fine.
If the straight isn't quite long enough then the lighter car may have hit top speed, but the heavier car may not quite have got there.

regds

[tony]

Are planks actually made of wood? I vaguely remember an announcer saying they just looked like wood because wooden planks were used when molding. I could be totally wrong. Does anyone else remember hearing this?

[Gemini]

Originally posted by tony
Are planks actually made of wood? I vaguely remember an announcer saying they just looked like wood because wooden planks were used when molding. I could be totally wrong. Does anyone else remember hearing this?

Earlier this year Jaguar presented some of its accounting records. It reads it's wood, expensive wood:

Underbody plank/skidblock (wooden)
$1,220 each, 60 used per year

http://www.dailyf1.c...nuary/07c.shtml

[Garagiste]

I will never forget Jimmy Greaves on a Sports discussion programme (paraphrase from distant memory) :
"So you're telling me you get this multi-million pound car, designed in a wind tunnel, made from exotic composties and then you screw a wooden plank to the bottom of it?

It takes a non-fan to remind us all how absurd our sport can be sometimes!

[Ali_G]

Originally posted by Al.



To recap a heavier car is able to corner at a higher speed because the weight is translated to a vertical force pushing the car to the ground, the higher the force the greater the grip, something that is taken further with aerodynamic downforce.

A heavier car is not able to corner at a higher speed than a lighter car. While a heavier car has more grip it also has a lot more side ways forces acting on it compared to a lighter car. hence a lighter car will always corner faster.

Niall

[DEVO]

Originally posted by Ali_G


A heavier car is not able to corner at a higher speed than a lighter car. While a heavier car has more grip it also has a lot more side ways forces acting on it compared to a lighter car. hence a lighter car will always corner faster.

Niall

With everything else being equal then yes.... (engine, tires, aero, etc...)... please read above statement about MASS... there is no such thing as sideway forces (in the scenario that you are describing).

[baddog]

Originally posted by Ali_G


Isn't Centripedal force the force that draws traveelin in an arc into the centre of the arc ?

Niall

yes you are correct I worded that all wrong.

centripetal force is the force needed to make the object turn. this leads people to imagine there is an equal force pulling the object outwards. this is not in fact the case however, the force that exists pulls the object in a straight line in its current direction of travel not outwards, the 'centifugal force' is merely an expression of that force in the effect it has on the object.

Shaun

[Tec Freak]

Originally posted by tony
Are planks actually made of wood? I vaguely remember an announcer saying they just looked like wood because wooden planks were used when molding. I could be totally wrong. Does anyone else remember hearing this?

Beginning in 2002, I believe, "the plank" no longer is made of wood. The previously quoted tech reg includes a phrase saying the skid block shall:

"be made from an homogeneous material with a specific gravity between 1.3 and 1.45."

water has a specific gravity of 1.00. Wood floats, and thus has a specific gravity of less than 1.00. There are a few types of exotic hardwoods with a specific gravity slightly above one, but I don't believe any reach 1.3. I believe the plank now is made of kevlar or, as Eddie J has so fondly put it, some supersecret form of "unobtainium"

[fuzzybunny]

Originally posted by X-ray

I think it's important to add that top speed is still the same no matter the weight. Acceleration on the other hand is less the higher the weight is and vice versa. So in practice a car with a full fuel tank has a lower top speed at Les Combes for example than a light car because of less acceleration.

Precisely why I said less weight = more speed [b]at point x[b]....

To recap a heavier car is able to corner at a higher speed because the weight is translated to a vertical force pushing the car to the ground, the higher the force the greater the grip, something that is taken further with aerodynamic downforce.

The extra mass also has to be accelerated sideways in a curve, effectively nullifying the downwards effect. Which is where aero downforce comes in. It adds vertical load WITHOUT the extra mass/inertia.

[maclaren]

Originally posted by DEVO
With everything else being equal then yes.... (engine, tires, aero, etc...)... please read above statement about MASS... there is no such thing as sideway forces (in the scenario that you are describing).

Yes there are, if we consider car being the cente of coordinates we use. There are forces to every direction ;)

[fuzzybunny]

Originally posted by maclaren

Yes there are, if we consider car being the cente of coordinates we use. There are forces to every direction ;)

From "The Cartoon Guide To Physics" by Larry Gonick.

"Recall the accelerometer ball we hung from Ringo's roll bar. It hangs backward when he accelerates, but why?

There are only two real forces on the ball: Gravity which pulls downward with magnitude mg, and the tension T on the string. When Ringo accelerates, the total of these two must point forward with magnitude 'ma', by Newton's second law - so the string must hang at an angle. But, Ringo in the car imagines a strange "acceleration force" pushing everything backwards! But there is nothing doing the pushing. The 'FORCE' IS FICTITIOUS, an effect of INERTIA resisting the car's acceleration.

All the sideways and back and forth forces you feel while driving are FICTITIOUS, the results of your inertia resisting acceleration "

Come on guys, this isn't subjective opinion, its kinda physics 101.

[DOHC]

Originally posted by baddog


yes you are correct I worded that all wrong.

centripetal force is the force needed to make the object turn. this leads people to imagine there is an equal force pulling the object outwards. this is not in fact the case however, the force that exists pulls the object in a straight line in its current direction of travel not outwards, the 'centifugal force' is merely an expression of that force in the effect it has on the object.

Shaun

The best post so far on centripetal/fugal effects.

There's a lot of confusion on this issue. A lot of people claim that there is no "centrifugal force." Even universities teach that, so that students will avoid making certain well-known standard mistakes in mechanics. There's a number of traps and pitfalls. Everybody makes them.

But centrifugal force certainly exists. To turn the car, a force must be applied to it (from the ground, via the way you turn the front wheels); this force corresponds to the centripetal acceleration. The car moves in a curved trajectory, hence even at constant speed its motion is accelerated -- acceleration is change of velocity; velocity is speed + direction; direction changes; hence velocity changes even if speed is constant in a corner; because velocity changes there is acceleration: centripetal acceleration. According to Newton's second law, there is a force corresponding to that acceleration. For simplicity we might call it lateral force.

But according to Newton's law of action and reaction, the car exerts the same force, but in opposite direction, on the road. This is the centrifugal force. It exists in a relative, accelerated (hence non-inertial) coordinate system attached to the car. It is perceived as a force, and exists as a force, only in this moving coordinate system. (Ask a driver, or tell him that centrifugal force doesn't exist -- he will laugh at you, he spends an hour and a half being thrown around in the cockpit because of centrifugal force.)

The statement that centrifugal force doesn't exist comes from the view that motion can only be described in an inertial frame of reference, or in some "magical" absolute coordinates. That's nonsense. There is (for practical purposes) an inertial frame of reference called the track, but there is an equally valid reality in a moving frame of reference called the car. As seen from the track, there is no centrifugal force, only centripetal acceleration, but as seen from the car, there is only centrifugal force.

[DOHC]

Originally posted by fuzzybunny
All the sideways and back and forth forces you feel while driving are FICTITIOUS,

Nonsense.

Originally posted by fuzzybunny
the results of your inertia resisting acceleration "

Correct.

Originally posted by fuzzybunny
Come on guys, this isn't subjective opinion, its kinda physics 101.

And that's the problem, because in Physics 101 you don't learn about non-inertial frames of reference. There's more to physics than the first course.

[baddog]

Originally posted by DOHC

. As seen from the track, there is no centrifugal force, only centripetal acceleration, but as seen from the car, there is only centrifugal force.

which was what I was driving at earlier when I said something like 'it only exists in the practical 'kill you' sense'

Shaun

[fuzzybunny]

Originally posted by DOHC

Nonsense.

Correct.

And that's the problem, because in Physics 101 you don't learn about non-inertial frames of reference. There's more to physics than the first course.

Might I suggest you refer you comments to the author of the book?
Since I merely was quoting from it.

Or try a search for "fictional forces" and argue with the people you find.
Or whatever.

Subject over?

[fuzzybunny]

Originally posted by DOHC
Even universities teach that

Aaah that'll be the problem, I was using that newfangled book-learning...;)
Seriously, though, "fictional force" is a term. Your beautiful explanation will not make it go away.
However It certainly clears things up a bit.
Perhaps I should have added:
Just cos a force is fictional, doesn't mean it doesn't exist...

If you get my lateral drift....

[maclaren]

Originally posted by fuzzybunny
Come on guys, this isn't subjective opinion, its kinda physics 101.

I'm not going to argue physics in english as I mainly had my physics courses (only basic UNI courses) in finnish.

[Pingu]

Originally posted by Tec Freak


Beginning in 2002, I believe, "the plank" no longer is made of wood. There are a few types of exotic hardwoods with a specific gravity slightly above one, but I don't believe any reach 1.3. I believe the plank now is made of kevlar or, as Eddie J has so fondly put it, some supersecret form of "unobtainium"

All the F1 cars use the same material: a densified wood laminate called "Jabroc."



Check out:

http://www.permalide....co.uk/hydu.asp

[fuzzybunny]

Originally posted by maclaren

I'm not going to argue physics in english as I mainly had my physics courses (only basic UNI courses) in finnish.

No arguments here.
I accept that my views are somewhat naive compared to yours and DOHC's knowledge.
Thanks very much for yours and DOHC's input, I am now a more complete armchair expert!

Besides, your knowledge of English beats the hell out of my knowledge of Physics.
I don't even want to think about what your Physics would do to my Finnish!

[DOHC]

Originally posted by baddog
which was what I was driving at earlier when I said something like 'it only exists in the practical 'kill you' sense'

Shaun

Yep I got that.

[DOHC]

Originally posted by fuzzybunny
Seriously, though, "fictional force" is a term.

Er, I don't think so. In physics, the qualifying word must always be properly defined with a unique meaning. How do you define fictional?

What you are thinking of is that centrifugal force does not exist in an inertial frame of reference. (Why of course, the frame of reference isn't accelerated!) But it exists and is as real as any in an accelerated reference frame. Maybe you know that there's tide on the side of Earth facing the Moon, but also on the side of the Earth facing away from the Moon? Go figure why! (Hint: Our Earth, although it might seem very inertial, is an accelerated reference frame -- nobody had that figured out before Newton, and most people still don't understand it.)

There are lots of forces, like inertial force, electromagnetic force, gravity [force], contact force, static force, constraint force, centrifugal force, friction force, reaction force, thrust [force], etc. There's even "down"force and "lateral" force ;) ! In all cases the qualifier has a precise meaning. But fictional force? No.

I'm sorry, but your Physics 101 course tricked you a bit, they use a simplified explanation, because things are a bit harder than they might at first seem. And putting in accelerated frames is something you can't do in 101. Go on to the next course...