Metric vs Imperial units

[xpensive]

We are going completely off topic here marcush, but I see two different problems here;

- The lack of technical focus in most threads.

- The poor attention to detail in posts, verbaly as well as edition-wise. I have to admit that I enjoy WB's contributions, while I rarely agree as he more often than not pisses me off big time, but he's got an xcellent vocabulary and cares about the editing side, the kind of professionalism I'm such a sucker for.

Anyway, one prominent bio-fuel plant in Sweden went belly up in the 90s, when they had metric tons confused with cubic meters in their business plan, after 20 years of being in the red.

[Just_a_fan]

It's actually a practical unit when discussing aerodynamic improvements among peers.

It has the benefit that teams can talk in public about improvements without telling their competitors the actual performance of their package. Because each car will have its own C, then CL is also unique to each design but points are relative between designs. Thus if both RB and McLaren declare they have 100 points of d/f it doesn't mean they both have the same d/f in terms of N. If each team claims a "3 point improvement" then they both know each is improving but neither team gives away exactly what the improvement is in terms of N.

It's the only way the teams can talk technically without giving away details that they need to keep secret. The only other option is for the teams to say nothing and that is not good for anyone.

[Tim.Wright]

That is the problem nobody knows what it is.
When these guys stand in front of the camera then they speak to millions of people and none of them knows this unit. It's just their very lame way to lie to the fans or simply just hide their lack of knowledge.
Then they come up with sentences like Redbull has twice the points of downfoce than we have or this idea from Hamilton improved the car by 3 points of downforce.
All just trash talk.
They should remember that they stay in front of this camera to say anything to the people out there.
Not to pleasure themselves or the journalist.
You either stay silent or you are honest and bring real figures.
Every technical minded fan or engineer should get very angry about that.

There is only one unit for downforce and this is NEWTON.
When you want to be exact you say you have xxx N downfoce at a speed of yyy m/s.
This is the only way to do it.

You can come up now and say points are common in F1.
I tell you something can be common but it doesn't change the fact that it is big bullsh!t.

Chill man. Its not the engineers duty to stand in front of the camera and say anything to you. Counting downforce in points is quite common, just because you dont understand it doent mean its BS. Its usually 0.1 of the coefficient which by the way is a perfectly acceptable measure for downforce. The whole point of the Cl value is that you dont need to know the velocity.

Team A saying they have -583kN of lift at 200km/h and team B saying the have -1312kN at 300km/h is only going to confuse people. How is that easy to understand? Do you really expect them to spill numbers like that anyway?

Tim

PS. By the way, Team A and Team B both have a Cl of 1.2

[marcush.]

I agree there ,especially with being too lazy with posting ,also from my side.
but i just have to add a funny thing related to someone completely missing the boat on a trivial every day conversion:
it was pre € days when I was planning a trip to britain and fancied some belgian francs(petrol stations are rare on the trip!) so I ordered the equivalent for 100 Deutschmark in my housebank and tell you what ...they called me by telephone and asked how I would collect the money...I did not understand in the first moment so I went over with a bag and was totally amazed by all the packs of francs I should receive for my 100DM.. Tell you what..the banker got the exchange rate crossed up or whatever he was thinking .. he had ordered Francs for 100.000DM...only after I insisted (!) that this could never be correct the clerk rechecked and his face colour was turning as red as it possibly could..

[mep]

Steve are you talking about the coefficient of lift with C_L?
This makes at least a bit more sense now but is still misleading.
When they want to talk about lift coefficient they should do so and name it so.
Coefficient of lift and drag is a common known term, points are worth noting.
There is no need to talk about points.
It's only to fool the listeners. Just because an improvement by 3 sounds better than 0.3.
Someone else on this forum said it’s referred to a on track improvement of a given time.
In the end we become misled because just very few people know about the meaning and we can't handle the figure so speaking about points to a camera is a very disrespectful behavior.

By the way a Lift coefficient improvement by 0,3 sounds very much to me for just adding a new wing. Frankly I don't believe it. It's the same as I don't believe Redbull has twice the downforce of McLaren.
I don’t see this to be proved on track.


Are you guys really defending the use of points?
Is it only me who is annoyed by this sort of trash talk.

Chill man. Its not the engineers duty to stand in front of the camera and say anything to you. Counting downforce in points is quite common, just because you dont understand it doent mean its BS. Its usually 0.1 of the coefficient which by the way is a perfectly acceptable measure for downforce. The whole point of the Cl value is that you dont need to know the velocity.

There is no need to divide the CoL by 10.
It's is not commonly known. Maybe in their team but when they talk to the camera they have to stick to common known units.
Where would we end up when everybody starts to make his own units?

[marcush.]

Steve are you talking about the coefficient of lift with C_L?
This makes at least a bit more sense now but is still misleading.
When they want to talk about lift coefficient they should do so and name it so.
Coefficient of lift and drag is a common known term, points are worth noting.
There is no need to talk about points.
It's only to fool the listeners. Just because an improvement by 3 sounds better than 0.3.
Someone else on this forum said it’s referred to a on track improvement of a given time.
In the end we become misled because just very few people know about the meaning and we can't handle the figure so speaking about points to a camera is a very disrespectful behavior.

By the way a Lift coefficient improvement by 0,3 sounds very much to me for just adding a new wing. Frankly I don't believe it. It's the same as I don't believe Redbull has twice the downforce of McLaren.
I don’t see this to be proved on track.


Are you guys really defending the use of points?
Is it only me who is annoyed by this sort of trash talk.

+1

[Just_a_fan]

@mep

I'm amazed that someone on a technical forum is annoyed at the use of a specialist technical term.

If you had your way regarding use of Newtons, the teams would either refuse to talk to the public or they would use made up numbers. Neither of which is an improvement.

[marcush.]

just to keep a bit off topic,I´m absolutely sure Hamilton has no idea of what sort of points he is talking of it is just filtered pseudoinfo nobody could ever derive useful information from that.
He would possibly not even know which components were responsible for the gains and what side effects led to the statement of added so and so much points.
AND ,rule No1 in everything life :
don´t assume anything !
so as long as he has not comfirmed that we are talking of fractions of percents the information is as god as if he said we have improved technically.

[xpensive]

On topic.
What perhaps surprised me the most when working in PA, was the wreckless use of "pounds", it took me quite a while to realize this could relate to either mass, force, torque or pressure, you never knew which. As JT said, "you just know".

[mep]

@mep

I'm amazed that someone on a technical forum is annoyed at the use of a specialist technical term.

It is not a special techincal term.

Is there any public declaration about points?
Is it a SI unit?
Will you find any paper about it?
Can you fing anything about it?
No!

Only Cl is. I have no problem when they us Cl.

[Tim.Wright]

...so speaking about points to a camera is a very disrespectful behavior.

I'm sure Adrian Newey, Ross Brawn etc aren't loosing any sleep over this. Perhaps you would prefer they say nothing?

Personally I think the reason they divde Cl by 10 (or 100 I can't remember now) is the same reason we speak in mm instead of m. Its easier to speak in whole round numbers.

Anyway, they can't use Cl. You said yourself its forbidden

There is only one unit for downforce and this is NEWTON...
...This is the only way to do it.

[mep]

I said this regarding the force.
In fact when you speak of downforce as they did then I am right they must use Newtons. When they talk about CL then they get around the speed problem and the force can be calculated from it. In fact mixing Cl and talking about force is not super correct and we don't know exactly the area they have.
Anyway I am not so super strict in this. They can talk about the Cl, I would even allow a driver or journalist talk about tons or kilograms of downforce.
I just don't accept points.

Personally I think the reason they divde Cl by 10 (or 100 I can't remember now)

hahahaha
you see even you got confused now and can't say for sure what it is.

I'm sure Adrian Newey, Ross Brawn etc aren't loosing any sleep over this. Perhaps you would prefer they say nothing?

When they speak to the camera they don't speak to Ross or Newey they speak to the fans. Never forgett this. And yes I prefer them to say nothing instead of fooling the audiance. What they do is a big bluff. People from other teams can figure out anyway what it is so its just to fool the audiance.
Its PR nothing else. Not technical minded people will believe their poor excuses.

[tok-tokkie]

From a thread of a March/April:

I agree with newbie and mistery steve.

Downforce=0.5*(air density)*(speed)^2*(reference area)*Cl

Usually you don't work with Cl, but with [reference area*Cl], namely SCl.
SCl has the dimension of surface, i.e. m^2 in SI; typical values are between 2 and 5.

1 point corresponds to SCl=0.01m^2:
if your car improves from SCl=4 to SCl=4.30 it has gained 30 points of downforce.

Working with points is easier because you work with numbers like 5, 7, 30 instead of 0.05, 0.07, 0.30.

If in the formula for downforce you substitute air density=1.22 kg/m^3 and take into account dividing by 3.6^2 (conversion for speed from m/s to kph) and by 9.81 (conversion from N to kg) you get

Downforce=0.0048*(speed in kph)^2*SCl

and finally with 1 point corresponding to SCl=0.01m^2

1 point [kg] = 0.000048*(speed [kph])^2

Thread: viewtopic.php?f=6&t=8286&view=previous

[Pup]

Engländer? Blasphemy, nothing less, marcush.

I wouldn't stand for it, X. Volvo may be Chinese, and Trollhätten a Dutch protectorate, but ceding your spanner technology to the British will be the end of the kingdom. For sure.

By the way, the proper term is "wrench", with the adjustable version called a "crescent wrench".

[xpensive]

Well again Pup, things come and go, but if the Germans starts calling hairy 70s porn anything less than "Ein Schwedenfilm", I will be seriously pissed off.

"British erotica" wouldn't fly, would it now?