For some time we have understood that the tyre temps are not able to be used very accurately for doing a car setup. With the release of the Maclaren for the WFG some very close scrutiny will be paid to putting a car setup together as the prize job at the end of it does require good knowledge in this area of the car. Also for some time adjustments I make to correct a specific characteristic of the cars handling do not always make sense with the outcome. With most suspension adjustments having the greatest effect during any time other than going straight weight transfer plays a major part of what goes on. What I struggle with is the car being 869 kg heavier when adding 114 Litres of fuel. I also struggle with the car being suddenly 1771 kg lighter when taking a right hand corner at 69kmh or the car suddenly being 1305kgs lighter when taking a right hand corner at 90kmh. There are also times that both left or right side wheels show zero load and the car becomes half the mass it was when all wheels are on the ground and the vehicle is static. According to the data the game spits out, when one wheel is off the ground what ever mass was being applied to that wheel when static, suddenly no longer exist. Mass can not disappear it must go somewhere. I realise that Newtons of force are applicable to Mass X Acceleration, however without the acceleration we are left with the mass which can be expressed in KGs. For what ever I have misunderstood or misinterpreted I apologise but what are the thoughts of others. Anyone else seen the same thing? This data is after driving out on track with first 10 Litres of fuel and doing an out lap then stopping just after the start finish line, then the same process after putting the full 125 litres of fuel in the tank. This data is while leaving the pits stopping in pit lane for a few seconds to establish a starting mass. This is loosing 1305 KG while taking a left hand corner. Suspension trace does not show the car running over any curb or any great disturbance of the suspension travel. This one is loosing 1771kgs after taking a right hand corner. Suspension trace does not show the car running over any curb or any great disturbance of the suspension travel.
There are 9.8 (approximately) Newtons (N) to a kilogram (kg). Your 'mass change' of 13915 from 13046 is actually a change of 869N, which is 88.7kg, which at the 'usual' 0.74kg/L is just under 120kg. The fuel mass per volume may be slightly different in this car (it can be set in the mod). As for dynamic loads, you can easily end up with totals all over the place as the car body can be moving upwards, downwards, side to side, end to end. The springs also store and release energy which can obscure things. *When doing Maths in i2Pro, you can choose both the Result Unit, and the Display Unit, for the new expression. In this case you're adding channels with values in N, so you'd leave that as the result unit, then if you wish you can change the Display Unit to kg. Then i2Pro does the conversion for you and your kg will be correct.
If you want to prove something regarding static condition you should be driving constant speed and turning radius over a flat surface. Driving over bumpy surfaces should make the total tire load oscillate around its mean value until dampers stabilize. You have selected time spots where the car is showing least total force. This is clear since in both cases one of the tire was flying over the track. If you had taken some tenths later when that tire lands again you would have found greater values compared to pitlane static ones. However, considering that the most basic thing as understanding that force and mass are something different seems beyond your knowledge, I would say that you are playing to be an engineer.
Thanks Lazza for the info that helps somewhat. No sparkis that is not the case next samples of the wheel on the ground the values do not exceed static value and it never does. Why the need to denigrate those of us that may less learned lessons than others. IF you don't like what you read simply do not reply. No need to be angry. I openly state my possible misunderstandings yet still put myself up for ridicule in the hope of finding new lessons, no need to bash me when I am down.
Here you can find telemetry in two different situations. The first one is under controlled testing conditions. The second is from WFG at Silverstone. The test track is completely flat. There you can see that total tire load never goes down below the values with the car at zero speed which is around 13200 N for the fuel level I was using while hotlapping for WFG. In a real track this value is very noisy as the car has to go through bumps and height changes. As you can see there is no missing mass. And tire load exceeds by a lot static value when the car is at high speeds. Your claims are completely unfounded.
If force is mass x acceleration then at speed the amount of newtons have to be greater than static because we have added acceleration. As farvas I see it that is not the same as comparing static values. I either compare moving values at the same speed or static values not a mixture of both.
The reason why tire load increases with speed is due to downforce. With inverted aero you would get less tire load at higher speed compared to static. Nothing related to your speed and acceleration comment which only proves that physics is not your specialty.
speed and acceleration are two different things. Acceleration is the rate at which speed changes. Just like speed is at the rate at which location changes. But one does not tell us anything about the other. So when you drive a car you have several force generators at work. Aero can add downforce or it can add lift. Aero is sensitive to ride height and pitch. Aero is both drag and lift. In sim you can create any kind of car you want. No drag and no lift is just about choosing the right numbers. Then you have dynamic forces. When turning to left or right you create lateral force acting on the car via tires. When you go over bump your springs and dampers compress which increases the vertical acceleration (at standing still it is 9.82m/s^2 or so). When you go over crest the reverse occurs and tire load is reduced. Dampers also add complexity. If your rebound is high the car can jack itself up in long corners. Arbs also add to this. In any kind of situation that involves the car rolling you load the arb which is a spring. Also tires are springs. A car with solid rear axle will also develop unequal tire loads despite going perfectly straight simply due the rear axle geometry. All this can momentarily make the wheel loads more or less. To get reliable reading you always want to make sure the numbers are measured exactly the same way. Same speed, same lat Gs, same longitudinal Gs, same aero, same ride height, same sus geometry, flat surface, time of day, track grip... Repeatability is the most important aspect of testing.
It sounds like some confusion between mass and force. I believe force recorded in this case is vertical force. Mass does not change. The magnitude and direction of the acceleration changes. In the static situation tire load/force in Newtons is generated by mass and acceleration due to gravity(vertical and essentially constant). In dynamic situations the vertical force on the corner of a car can change due to force transfer. The force transfer is caused by actual dynamic lateral, longitudinal and heave(vertical) acceleration. Some of the lateral and longitudinal acceleration is translated into a vertical acceleration and some remains as lateral or longitudinal acceleration due to physical/dimensional constraints. The force transferred to a corner then is due to the lateral and longitudinal acceleration translated to vertical, plus any other vertical acceleration. The forces transferred are also impacted by the effect on vertical acceleration by the dampers and springs. The acceleration due to gravity is always there, so the tire force it generates just gets added to or subtracted from it. In other words, force transfer not mass transfer. Added to this are aerodynamic forces(which is effectively equivalent to adding mass). It gets confusing I think because we tend to understand the dynamic force change conceptually as fundamentally equivalent to the impact of a mass change. This is because mathematically we can associate the dynamic force by dividing by the constant acceleration due to gravity to generate a normalized equivalent mass. Hope that makes some sense? Cheers
Mind you, speed does add mass. You just need to be a lot closer to the speed of light for it to become significant
Thanks guys appreciate your responses and passing on your knowledge. I guess my quandry comes from a logical point of view where if I stand on two scales the total of the scales equals my total mass lift one leg and all the mass is now on one leg. No loss of mass. How come I am unable to apply the same logic with the car.
Logic error... if you hop into the air, like a car suspension after a bump, then there's no weight on the scale.
Easy: when you weight yourself you are static in your bathroom, and not rolling at 200 km/h with wheels under your scales. A car can take of from the track and fly in the woods... can you do it on your scale? I hope not
On a more serious note, elaborating what emery said, you can easily score several tons of load on your scale if you jump high over them, and just before hitting them again you push violently your feet down.
Instantaneous forces are not static loads. Your brain can survive instant acceletation of several tens G's ... but your whole body would turn into a goo if constant acceleration of 70 80 G's would be applied for several seconds.
Your bath room scales measure weight which is a force not a mass. So when you move both feet to one scale you are redistributing your mass, but the scale still measures the change as an increase in force. Mass is measured with a mass balance which is a different device. We think of them the same but they actually are not. When you are on the moon your mass would be the same as earth, but your weight/ force you exert on the moon surface is less because the acceleration due to gravity is less on the moon.
