Guarding the Forest - Drainage device 5A / 15A

APUs are designed to extinguish forest fires from the air or to fill ground tanks with water in the area of ​​forest fires.

This is necessary if a forest fire operates in a place where there are no natural water sources or there is no way to deliver water by land transport.

Considering that manual labor is the main way to extinguish forest fires, especially in remote and inaccessible areas where equipment cannot pass, the delivery of water in a soft container is an important factor in the fight against forest fires.

The APU is filled with water by taking water in the hovering mode of the helicopter from a reservoir with a depth of at least 1.5 m for the VSU-5A and 3 m for the VSU-15A. Filling time from 10 to 17 sec. The water is drained at a rate of 900 liters per second.

The drainage device has the shape of a basket and consists of a technical polyamide fabric, a frame of two metal rings and a drain valve.

The upper ring of the frame is partially filled with lead shot - it quickly drowns the APU, so a few seconds are enough to take five tons of water. The APU is attached to the helicopter on an external sling with a 20-meter cable. Draining is performed by the pilot-observer using the control panel.

The practice of using these devices has revealed the following problem - even 15 tons of water discharged into a forest fire are not effective enough. Burning on the surface stops, but the high temperature dries it out quickly. A light breeze is enough, and the tree flares up again. Therefore, in addition to the APU, another system is used - the SDP (Foamer Adding System).

The technology for extinguishing forest fires using the APU is as follows ... The helicopter with the APU is on duty at the airfield and is called to extinguish the fire by a patrol aircraft. The observer pilot, having received the message, analyzes it and selects a reservoir suitable for work, closest to the fire.

To select tactics for extinguishing a fire, the observer pilot with the helicopter commander calculates the fuel refueling, the permissible load for the delivery of the airborne fire brigade and cargo, and the helicopter takes off for the fire. After the paratroopers-firefighters have landed from the air, a landing site for the helicopter is selected with the engine turned off and the APU installed from the transport to the operating position, after which the helicopter is sent to the reservoir for water intake.

Aimed water discharge is performed by the observer pilot, who sets the flight mode to the crew, indicates the edge for extinguishing. At a helicopter speed of 50-70 km / h, water is drained from a height of 15 m above the forest canopy, as a result of which a wetted strip with a length of 75 to 230 m and a width of 10 to 20 meters is formed, depending on the APU models. The APU is transported on the suspension system of the Mi-8 MTV, Mi-26 helicopters. The spillway device has different capacities: 5 and 15 tons. The VSU-5A is installed on the Mi-8 MTV helicopter, and the VSU-15A on the Mi-26.