# Calculating Drag Increase with Airbrake: Semi Span

• Pulp
In summary, airbrakes are used on semi spans to increase drag and slow down the vehicle. The system works by using compressed air to activate the brakes on each wheel. Several factors affect the drag increase, including the size and design of the airbrake, vehicle speed and weight, and wind conditions. The drag increase can be calculated using a formula. However, there are also some disadvantages to using airbrakes, such as increased wear and tear on brakes and tires, and decreased effectiveness in wet or icy conditions.
Pulp
I need to calculate the increase in drag due to an airbrake, however the formula includes "semi span". I'm unsure if this is simply wing span/2 or is it the length of a wing in which case it would be (wing span - fuse width)/2. Any help would be good.

Semi span is half the wing span.

## 1. What is the purpose of using airbrakes on a semi span?

Airbrakes are used on semi spans to increase drag, which helps to slow down the vehicle and reduce its speed. This is especially important for large trucks and trailers when navigating steep or winding roads.

## 2. How does the airbrake system work?

The airbrake system on a semi span works by using compressed air to activate the brakes on each wheel. When the driver pushes the brake pedal, the air compressor releases air to the brake chambers, which pushes the brake pads against the wheels, creating friction and slowing down the vehicle.

## 3. What factors affect the drag increase with airbrakes?

The drag increase with airbrakes is affected by several factors, including the size and design of the airbrake, the speed and weight of the vehicle, and the wind conditions. The angle of the airbrake and the shape of the semi span's body can also impact the amount of drag increase.

## 4. How is the drag increase with airbrakes calculated?

The drag increase with airbrakes can be calculated by using the formula: Drag = 0.5 x ρ x V² x Cd x A, where ρ is the air density, V is the velocity of the vehicle, Cd is the drag coefficient, and A is the frontal area of the semi span.

## 5. Are there any disadvantages to using airbrakes on a semi span?

While airbrakes are an effective way to increase drag and slow down a vehicle, they can also cause increased wear and tear on the brakes and tires. Additionally, airbrakes can be less effective in wet or icy conditions, so it is important for drivers to still use caution and proper braking techniques when using airbrakes.

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