What Is an Air Cast?

Drop an item or person from an aircraft with an umbrella or other effective reduction gear.

According to the airdrop method of the airdrop system, the airdrop can be divided into traction continuous drop and gravity airdrop. The traction continuous drop is to pull the cargo out of the aircraft by the traction of the parachute, and the gravity airdrop is to pull the cargo out of the aircraft by the gravity. Traction airdrop is widely used because it is suitable for airdropping heavy cargo. This article mainly introduces the traction airdrop system. According to different traction methods, the traction airdrop system can be further divided into standard airdrop, low-altitude parachute traction airdrop, "MAISS" (main pipeline) traction airdrop and near-ground separation traction airdrop.

The airdrop capability of an aircraft refers to whether the aircraft can airdrop a specified weight and quantity of cargo in accordance with a prescribed airdrop method.

Airdrop system test

During the airdrop, the aircraft airdrop system worked according to a predetermined procedure. The test flight included the following items:

Through test flight, check the airborne environment adaptability, correctness of electrical and mechanical interfaces, correctness of system control logic, consistency of control and display, and equipment function and performance of personnel transportation, freight, airdrop, airborne, and mission management subsystems. Compliance with design requirements.

Check the completeness of the airdrop facilities.

Single, double and single continuous delivery of small pieces of cargo at selected heights. During the airdrop process of the cargo, check whether the logical control of the airdrop system meets the system control requirements, and whether the system display and light prompts meet the system use requirements. , Check the unlocking, directional movement, leaving the aircraft, opening the umbrella and the expected compliance with the design, provide video data of the airdrop process, and evaluate the safety of the cargo leaving the aircraft.

At the selected height, make a single shot of the middle piece cargo (weight is not greater than 10t). During the airdrop of the cargo, check whether the logical control of the airdrop system meets the system control requirements, and whether the system display and light prompts meet the system use requirements. Check the traction, unlocking, directional movement, departure of the cargo and the expected compliance with the design, and provide video data of the airdrop process. Assess the safety of cargo leaving the aircraft.

Mixed drop of people and goods at the selected height. Check whether the logic control of the system meets the system control requirements. The system's display and light prompts whether the system meets the requirements for use of the system, checks the traction, unlocking, directional movement, departure from the aircraft and the expected compliance, provides video data of the airdrop process, and evaluates the safety of personnel and the departure of the cargo.

In the process of cargo airdrop, check the cross-linking relationship of mission management subsystem, flight management subsystem and flight control system, as well as the correctness of data transmission, calculation of center of gravity and flight attitude control.

Combined with the flight test of the avionics integrated information processing sub-system, a preliminary assessment is made as to whether the mission solution accuracy of the system meets the design requirements, that is, whether the deviation between the actual cargo landing point and the intended landing point is within the required range.

Evaluate the impact of noise and vibration environment on the airborne work during airborne process (communication, communication, and safety of personnel in the cargo hold).

Check the consistency of system monitoring (video) and status prompts with the actual status of the cargo hold.

Check the electromagnetic compatibility of the system and evaluate the effectiveness of its electromagnetic environment control measures. ^[2]

Airdrop system composition

The airdrop sub-system of the aircraft is mainly composed of a central guide rail, an airdrop rolling track, a rod rolling track, an airdrop side guide, a traction parachute drop device, a mooring device, an auxiliary cargo bridge, an airdrop airdrop signal device, and an electric control device. The central guide rail is used to control the movement guidance in the airdrop cargo platform and lock or release the cargo platform. The air drop track is used to transport and support the equipment within the aircraft. The left and right outer rails are used to complete the movement guidance in the airdrop cargo platform and lock or release the cargo platform. The left and right auxiliary side guides are used to cooperate with the outer guides to complete the movement guidance in the airdrop pallet machine. Towing parachute drop device is used to suspend and drop the parachute.

The cargo platform system is mainly composed of a towing parachute system, a main parachute system, a landing disengagement lock, a suspension system, a cargo platform system, a traction lock and unlocking mechanism, a mooring binding device, a directional anti-rollover system, and an umbrella stand.

Towing parachute system is used to generate traction force when towing airdrop to pull cargo platform system out of the cabin. The main umbrella system is used to generate resistance. It consists of a landing disengagement lock, a suspension system, a cargo platform system, a traction lock and unlocking mechanism, a mooring binding device, a directional anti-rollover system, and an umbrella frame.

The normal working procedure of the standard traction airdrop is:

Before flight, the crew sets the Dingzhuo mode of the airdrop system according to the airdrop field location, the type of airdrop cargo platform and the airdrop method;

The plane enters the airdrop area according to the scheduled route;

The crew adjusted the attitude, speed and altitude of the aircraft according to the airdrop requirements;

When the aircraft reaches the airdrop point, the airdrop system sends an airdrop signal, and the crew presses the "airdrop" button;

The traction umbrella throwing mechanism throws out the traction umbrella, and the traction umbrella is straightened and full; ^[2]

List of airdrop systems

1. Low altitude parachute extraction system (LAPES: Low Altitude Parachute Extraction System)

When the transport aircraft is at a low altitude (for example, a C-17 transport aircraft can perform a low-altitude airdrop at a height of 3 meters above the ground), the parachute is thrown from the rear door of the cabin. After the parachute is inflated, the cargo is pulled out of the cabin to realize the delivery of heavy objects. The pulling force of the parachute is horizontal.

2.LVADS (Low Velocity Airdrop Delivery System)

At 500-700 feet or higher, pull out heavy objects from a low-speed aircraft, and the heavy objects are dropped into the ground by the parachute. During the landing, the pulling force of the parachute is in the vertical direction.