Movable Underbody Side Skirts for Downforce Without Drag

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Solution Overview

Problem

The installation of skirts on road-use passenger cars is made impossible by the multitude of humps, dips, depressions, and other asperities of urban or suburban roads, which can irreparably damage the skirts and violate static ground clearance regulations, while the presence of skirts increases aerodynamic drag and conflicts with the need for high vertical aerodynamic load (downforce) at high speeds.

Innovation Solution

A road-use motor vehicle with an underbody featuring side skirts that can vertically move between a fully lowered and raised position, controlled by an electronic system to adjust the distance from the ground based on vehicle speed, road conditions, and other parameters, using an inflatable structure to prevent air disturbance and protect against road impacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If skirts are installed on the underbody to increase downforce, then vertical aerodynamic load is improved, but aerodynamic drag increases

Engineering Contradiction:
Improvevertical aerodynamic load (downforce)VSAvoidaerodynamic drag
Core Design Contradiction:
ForceVSLoss of energy

Solution Approach 1:

The skirts are made movable rather than fixed, allowing them to dynamically adjust their position between a lowered configuration (for maximum downforce) and a raised configuration (for minimum drag). This dynamic adaptation resolves the contradiction by optimizing the balance between downforce and drag based on driving conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The underbody aerodynamic system is segmented into modular skirts that can be independently controlled and adjusted. This allows selective deployment of skirt sections to achieve the optimal balance between downforce generation and drag reduction without compromising overall vehicle performance.

Inventive Principle:
Principle #1Segmentation

2Force

If skirts are extended to graze the ground to prevent air disturbance, then downforce is improved, but reliability deteriorates due to road surface impacts

Engineering Contradiction:
Improvevertical aerodynamic load (downforce)VSAvoidskirt durability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The skirts are designed with movable capabilities, allowing them to dynamically adjust their height relative to the ground. When road asperities are detected or anticipated, the skirts can be raised to avoid impacts, thereby maintaining reliability while preserving the ability to generate downforce when conditions are favorable.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates sensors and control mechanisms that detect road surface conditions in advance, allowing the skirts to be positioned appropriately before encountering potential impacts. This proactive approach prevents damage before it occurs, maintaining both downforce performance and skirt reliability.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Force

If skirts are positioned to optimize aerodynamics, then downforce is improved, but ease of operation worsens due to ground clearance regulation compliance

Engineering Contradiction:
Improvevertical aerodynamic load (downforce)VSAvoidground clearance compliance
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The skirts are equipped with active control systems that automatically adjust their position to comply with ground clearance regulations when the vehicle is stationary or moving slowly, while allowing optimal aerodynamic positioning when the vehicle is traveling at higher speeds. This dynamic compliance eliminates operational restrictions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates sensors that monitor ground clearance conditions and provide feedback to the control system, which then adjusts skirt positioning accordingly. This closed-loop control ensures automatic compliance with regulations while optimizing aerodynamic performance when conditions permit.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution allows the skirts to maintain aerodynamic downforce without increasing drag, protects against road impacts, and ensures compliance with ground clearance regulations by dynamically adjusting their position, enhancing vehicle performance and safety.

Implementation Method 1

the flat shape of the underbody generates, beneath the passenger car, a depression (low-pressure air zone) which, in turn, generates a vertical force that tends to press the passenger car to the ground (downforce)

Methodology Applied
Scientific EffectAerodynamic downforce: Bernoulli Effect

Data Source

PatentEP4678519A1Road-use motor vehicle
Publication Date: 2026.01.14 FERRARI SPA
  • EP4678519A1 patent drawingFigure 1
  • EP4678519A1 patent drawingFigure 2
  • EP4678519A1 patent drawingFigure 3~4

AI summary

A road-use motor vehicle (1) comprising: a vehicle-body (2) provided with a plurality of ground-resting wheels (3, 4); a powertrain adapted to drive into rotation at least one of said ground-resting wheels (3, 4); an underbody (5), which is arranged to cover, or is integrated into, the lower part of the vehicle-body (2) so as to directly face the ground; at least one pair of side skirts (10) that extend cantilevered from the underbody (5), on opposite sides of a vehicle vertical midplane (M), and are structured so as to vertically move their lower longitudinal edge (10a); and an electronic control system, which is adapted to actuate said side skirts (10) so as to vary the ground distance (d) of said side skirts (10).