I was watching a car video and noticed that every time a car launches using launch mode, the front end of the car will rise a little just before the actual launch ([Example](https://youtu.be/opfbaluY7lc?t=150)). I understand why a car’s nose might rise during acceleration, but I don’t understand what happens during launch mode that causes this.
In: 3
When a car isnt moving then suddenly goes as fast as possible, it makes a lot of torque. That torque is being applied to the rear wheels trying to spin them as fast as possible. This creates an imbalance in the center of gravity, pushing it back, and as a result, the front end lifts a bit. Or a lot.
I watched your example video several times and didn’t see the nose rise at that time stamp. I’m on my phone, so maybe I’m just blind.
What I do see is the rear squatting down before the launch (not during). If these cars have an active suspension system, this could be done along with changing the damping to modify the amount of weight that transfers to the rear tires. The goal would be to maximize traction during the launch by using a suspension calibration which isn’t appropriate for normal driving.
You would probably not see the same behavior from a car which does not have a system allowing it to adjust it’s ride height (usually via air suspension), unless I’m misunderstanding what would cause this phenomenon.
Assuming a rear wheel drive and also a rear mounted engine, the front is quite light. As the power is applied the drive wheels push down and back on the tarmac, producing a torque in a clockwise direction if you are looking at the right hand side of the car. The opposite reaction force is anticlockwise, lifting the front or st least compressing the rear springs and extending the front ones.
if you try spinning a fairly heavy wheel with all your power using your hands, your body will more or less turn to the opposite direction of the spin. the same happens with the body of the car
Launch mode is a precisely timed group of events that maximize the starting torque power and speed to get the car off the line as fast as it can. When launch mode is on you hold down the gas all the way, but the car is drive by wire, so the throttle is electronic, so the cars computer doesn go full throttle but does rev. The breaks are applied to the car by the computer. The car gradually increases power to the rear wheels. Even though the breaks are applied on all 4 wheels the rear wheels will still turn forward ever so slightly this causes the back will to ride the back suspension down. You can achieve this simply by holding the break down in a rear wheel drive car and pushing the break down. You will notice the back rides down a bit and nose pops up. Because the computer is doing it is very gradual so it looks as it does in your vid. When the break is released and the car throttles forward the tongue pulls the nose up in a jerk.
This is for rear drive cars. If you look at a front wheel drive car, the car will squat slightly. Because the front wheels are slightly pulling away and dragging the card down a bit
Again if your in a normal front wheel drive car and hold the break and gas you will notice the car squat a bit.
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