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The Car thread

eric strt6

eric strt6

Resident Curmudgeon
Sep 8, 2001
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directly above the center of the earth
kidwoo

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
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Squirtin ketchup n' mustard on charred flesh
stevew

stevew

resident influencer
Sep 21, 2001
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pulling 5g and cracking your ribs

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PogonainsuranceTV on Instagram: "Toyota tested its TS010 Group C car, which was powered by a 3.5L N/A V10, in February 1992 at Eastern Creek in Australia, now known as Sydney Motorsport Park, before the last season of the World Sportscar Championship and the 60th edition of the 24 Hours of Le Mans. Hitoshi Ogawa and Andy Wallace found themselves breaking their ribs going through Turn 1 at 307 km/h (191 mph) due to the sheer downforce of around 2850kg (well over 6000 pounds), causing the two drivers to experience in the neighborhood of 5G. "I went through the corner and just felt this massive crack, and two ribs were broken instantly from just driving the car," Wallace explained. #WEC #WorldEnduranceChampionship #FIAWEC #FIAWorldEnduranceChampionship #WorldSportscarChampionship #GroupC #GroupCProtoype #Prototypes #Toyota #ToyotaTS010 #EasternCreek #SydneyMotorsportPark #Australia #LeMans #LeMans24 #24HoursOfLeMans #Motorsport #PogonaInsurance #PogonaRacing"

270K likes, 1,195 comments - pogona_tv on December 19, 2023: "Toyota tested its TS010 Group C car, which was powered by a 3.5L N/A V10, in February 1992 at Eas..."
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Jm_

Jm_

sled dog's bollocks
Jan 14, 2002
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stevew said:
pulling 5g and cracking your ribs

www.instagram.com

PogonainsuranceTV on Instagram: "Toyota tested its TS010 Group C car, which was powered by a 3.5L N/A V10, in February 1992 at Eastern Creek in Australia, now known as Sydney Motorsport Park, before the last season of the World Sportscar Championship and the 60th edition of the 24 Hours of Le Mans. Hitoshi Ogawa and Andy Wallace found themselves breaking their ribs going through Turn 1 at 307 km/h (191 mph) due to the sheer downforce of around 2850kg (well over 6000 pounds), causing the two drivers to experience in the neighborhood of 5G. "I went through the corner and just felt this massive crack, and two ribs were broken instantly from just driving the car," Wallace explained. #WEC #WorldEnduranceChampionship #FIAWEC #FIAWorldEnduranceChampionship #WorldSportscarChampionship #GroupC #GroupCProtoype #Prototypes #Toyota #ToyotaTS010 #EasternCreek #SydneyMotorsportPark #Australia #LeMans #LeMans24 #24HoursOfLeMans #Motorsport #PogonaInsurance #PogonaRacing"

270K likes, 1,195 comments - pogona_tv on December 19, 2023: "Toyota tested its TS010 Group C car, which was powered by a 3.5L N/A V10, in February 1992 at Eas..."
www.instagram.com www.instagram.com
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5G is cracking their ribs? What are these guys made out of?
 
Jm_

Jm_

sled dog's bollocks
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Westy said:
Jerk


Hard initiation of a turn will have extremely high jerk values, so if one isn't literally clamped into a seat will basically create an impact. Being a wet bag of meat the human body isn't good at responding to jerk.
https://en.wikipedia.org/wiki/Jerk_(physics)
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Well ok, but that would be a hell of a lot more than 5G. Acceleration is change in V over time, so if it's a much smaller period of time...much higher Gs. Otherwise, pilots would be breaking ribs all the time and 5Gs is significant...but not bone-breaking. (yes, rare for pilots to be pulling more than a couple Gs outside of aerobatics, but I deal with aerobatics quite a bit-and military).
 
Westy

Westy

the teste
Nov 22, 2002
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Sleazattle
Jm_ said:
Well ok, but that would be a hell of a lot more than 5G. Acceleration is change in V over time, so if it's a much smaller period of time...much higher Gs. Otherwise, pilots would be breaking ribs all the time and 5Gs is significant...but not bone-breaking. (yes, rare for pilots to be pulling more than a couple Gs outside of aerobatics, but I deal with aerobatics quite a bit-and military).
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An airplane cannot transition into that 5G turn nearly as fast as a car. As not only does the control surface need to move, the aircraft requires secondary rotation to change the angle of attack to change the G rates. With a car that jerk is limited by just the rigidity of the chassis and tires. Basically a car can go from 0G to 5G much much faster than an airplane. This means nothing for a rigid body but means a lot for non rigid systems, especially those with "lost motion". One of the tricky things about concussions, the brain smacking the inside of your skull can see much higher G rates than the skull itself.

Think about driving with a cup of coffee in your car. You can enter a corner with a slowly decreasing radius and eventually hit 1g. The coffee will slowly move to one side of the cup and end up with the surface at 45 degrees. If you turn in as fast as you can into a 1g turn that coffee will move a hell of a lot more and slosh out of the cup.

Also an airplane may be able pull much higher Gs than a car, but that is primarily in the vertical axis The vertical stabilizer can generate a lot of rotational forces but very little lateral force.
 
Jm_

Jm_

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Westy said:
An airplane cannot transition into that 5G turn nearly as fast as a car. As not only does the control surface need to move, the aircraft requires secondary rotation to change the angle of attack to change the G rates. With a car that jerk is limited by just the rigidity of the chassis and tires. Basically a car can go from 0G to 5G much much faster than an airplane. This means nothing for a rigid body but means a lot for non rigid systems, especially those with "lost motion". One of the tricky things about concussions, the brain smacking the inside of your skull can see much higher G rates than the skull itself.

Think about driving with a cup of coffee in your car. You can enter a corner with a slowly decreasing radius and eventually hit 1g. The coffee will slowly move to one side of the cup and end up with the surface at 45 degrees. If you turn in as fast as you can into a 1g turn that coffee will move a hell of a lot more and slosh out of the cup.

Also an airplane may be able pull much higher Gs than a car, but that is primarily in the vertical axis The vertical stabilizer can generate a lot of rotational forces but very little lateral force.
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I don't think you are tracking here.

If you transition faster...it's not 5G, because the time is shorter.
 
Westy

Westy

the teste
Nov 22, 2002
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Jm_ said:
I don't think you are tracking here.

If you transition faster...it's not 5G, because the time is shorter.
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A rigid body can go from 0G to 5G in many different ways without ever exceeding 5G. There is a real difference between the rate in change of velocity and the rate in change of acceleration and the effects on the human body is real. I will happy to provide a mathematical example if necessary.

This is a real problem for CNC machines and other motion control systems. If you say are machining a square with radiused corners the machine literally cannot transition from a straight line into a smooth constant radius corner as the "jerk" is infinite and would require a system with an infinitely high rigidity or frequency response. To properly control the system a smoothly shaped acceleration profile must be part of the interpolated trajectory.
 
Jm_

Jm_

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Westy said:
A rigid body can go from 0G to 5G in many different ways without ever exceeding 5G. There is a real difference between the rate in change of velocity and the rate in change of acceleration and the effects on the human body is real. I will happy to provide a mathematical example if necessary.

This is a real problem for CNC machines and other motion control systems. If you say are machining a square with radiused corners the machine literally cannot transition from a straight line into a smooth constant radius corner as the "jerk" is infinite and would require a system with an infinitely high rigidity or frequency response. To properly control the system a smoothly shaped acceleration profile must be part of the interpolated trajectory.
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If the "jerk" is infinite, it's infinite Gs, so yeah. Ultimately it's a measure of acceleration, which is controlled change in velocity over time.
 
Jm_

Jm_

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Just one final question your honor, what happens to the acceleration when you decrease the time?
 
Westy

Westy

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Nov 22, 2002
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Jm_ said:
Just one final question your honor, what happens to the acceleration when you decrease the time?
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There is not enough information in that question to be answered.

Think of it like "turn in". In a car your constant cornering acceleration is pretty much solely based on the vehicle speed and steering angle.

so if you are driving at a constant speed in a straight line and slowly turn the wheel to 45 degrees, you will have slow turn in (jerk), into a constant G turn.

Do the same thing but turn the wheel to 45 degrees as fast as you can, you will have higher turn in and jerk, into a constant G turn.

You can try that in autocross, the faster turn in maneuver will feel a lot more violent and at some point you will exceed the car's capability despite never trying to exceed it's constant cornering acceleration limit. All else being equal, faster low speed damping in a car's suspension with affect it's turn in or jerk limits. Snap, Crackle, and Pop also come into play but that is even more complicated.
 
Jm_

Jm_

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Westy said:
Do the same thing but turn the wheel to 45 degrees as fast as you can, you will have higher turn in and jerk, into a constant G turn.
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But that right there is not a constant acceleration, and therefore not constant Gs, but much more.
 
Westy

Westy

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Jm_ said:
Does it matter? It's not 5G.
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It is the difference is how quickly you get to 5G. How quickly the change in force is applied and dynamic systems respond. Now because of that a person inside a car entering a 5G turn may experience more acceleration as their flesh may be able to handle 5g, it cannot respond to high jerk and will deflect and 'overshoot' causing an impact and higher Gs. It is actually more of a frequency response issue but I don't think that conversation will help.
 
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Pneuma

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Nov 5, 2021
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Westy is correct.
1703221773432.png

If an object has constant speed along this path the red portion experiences jerk. A changing radius = changing acceleration over time. Third derivative of position. It’s an interesting concept that I never think about but it is clearly used in road and rail design.
 
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kidwoo

kidwoo

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Pneuma said:
It’s an interesting concept that I never think about but it is clearly used in road and rail design.
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AND BREAKING BITCHES SPINES!


Is jerk what I experienced with a rapid change in acceleration with my own spine against a tree? I definitely called that tree some things, 'jerk' may have been one of them. Might have even been some fourth order swearing.
 
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Pneuma

Chimp
Nov 5, 2021
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I would guess your spine experienced snap (4th) crackle (5th) and pop (6th). All of which are beyond my grasp of understanding in the physical world.
 
Jm_

Jm_

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Pneuma said:
Westy is correct.
View attachment 205392
If an object has constant velocity the red portion experiences jerk. A changing radius = changing acceleration over time. Third derivative of position. It’s an interesting concept that I never think about but it is clearly used in road and rail design.
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Constant velocity in what direction? Velocity is a vector, no? It still seems to me that the velocity is changing far more over time in the red portion than any other, hence, more acceleration, vs the constant in the green circle.

The instantaneous Gs in that red portion will surely be above the steady state.
 
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