Car Tuning Aerodynamics and Body Styling 5 — Questions and Answers
Question 1: What is 'pressure drag' (also called form drag) in automotive aerodynamics?
- Drag caused by tire deformation under load
- Resistance from the pressure difference between the high-pressure front and low-pressure wake behind the car (Correct answer)
- Friction between the underbody and road surface
- Aerodynamic resistance caused by spinning wheels
Correct answer: Resistance from the pressure difference between the high-pressure front and low-pressure wake behind the car
Pressure drag arises because high-pressure air at the front cannot fill the low-pressure wake at the rear fast enough, creating a net rearward force.
Question 2: Why do Formula D-style drift cars often run very little or no rear wing despite needing rear grip?
- Rear wings are banned by competition rules entirely
- High rear downforce would make oversteer harder to initiate and sustain (Correct answer)
- Rear wings add too much weight for performance
- Rear downforce has no effect on oversteer angle
Correct answer: High rear downforce would make oversteer harder to initiate and sustain
Excessive rear downforce plants the rear tires firmly, making it harder to break traction and hold a sustained drift angle.
Question 3: How does lowering ride height affect the aerodynamic performance of a car with a flat underbody?
- It reduces downforce by limiting underbody airflow volume
- It increases ground effect by accelerating underbody airflow through a narrower gap (Correct answer)
- It has no measurable aerodynamic effect
- It mainly reduces frontal area to cut drag
Correct answer: It increases ground effect by accelerating underbody airflow through a narrower gap
A smaller gap between the underbody and road forces air to accelerate more, lowering pressure beneath the car and increasing downforce through ground effect.
Question 4: What is the risk of 'bottoming out' the diffuser on a lowered car?
- The diffuser overheats and deforms from exhaust proximity
- Ground contact disrupts airflow, instantly destroying downforce and causing instability (Correct answer)
- It causes the fuel tank to pressurize
- It damages the rear axle differential mount
Correct answer: Ground contact disrupts airflow, instantly destroying downforce and causing instability
When the diffuser contacts the ground, the carefully managed airflow is catastrophically disrupted, causing sudden downforce loss and potential high-speed handling failure.
Question 5: What advantage does a 'swan neck' rear wing mount offer compared to traditional bottom-mounted struts?
- It is significantly lighter than bottom mounts
- It attaches from above, keeping the wing's lower surface unobstructed for better aerodynamic efficiency (Correct answer)
- It allows the wing angle to be adjusted while driving
- It provides a mounting point for brake lights
Correct answer: It attaches from above, keeping the wing's lower surface unobstructed for better aerodynamic efficiency
Swan neck mounts attach to the top of the wing, leaving the critical lower pressure surface clean and undisturbed for maximum downforce generation.
Question 6: In body styling, what is the purpose of a 'chargespeed' or wide-body conversion that adds 30–50mm per side?
- Solely to improve the car's appearance for shows
- To accommodate wider track, larger tires, and improve mechanical grip alongside styling (Correct answer)
- To satisfy legal requirements for aftermarket wheel offsets
- To reduce the car's polar moment of inertia
Correct answer: To accommodate wider track, larger tires, and improve mechanical grip alongside styling
A proper wide-body conversion allows fitting wider wheels and tires for more mechanical grip, with the broader stance also improving dynamic stability.
Question 7: What is 'aero wash' and how does it affect a closely following race car?
- Cleaning carbon fiber panels with specialized solvents
- Turbulent disturbed air in the wake of a leading car that reduces downforce on the following car (Correct answer)
- Water spray from wet roads that disrupts underbody airflow
- Wind buffeting caused by open windows at speed
Correct answer: Turbulent disturbed air in the wake of a leading car that reduces downforce on the following car
A leading car's turbulent wake reduces the quality of airflow reaching a following car's wings and underbody, cutting its downforce and grip.
Car Tuning Aerodynamics and Body Styling 5
What is 'pressure drag' (also called form drag) in automotive aerodynamics?