The BRDM-1 (Bronirovannaya Razvedyvatelnaya Dozornaya Mashina, Бронированная Разведывательная Дозорная Машина, literally "Armored Reconnaissance/Patrol Vehicle" †) was an amphibious armored scout car used by Russia and the former Soviet Union. It was originally known simply as BRDM but when the BRDM-2 entered production and service with Soviet Army in 1962, it received the designation BRDM-1. The BRDM (also known as the BTR-40P) first appeared in 1957, and was in production until 1966. Total production was around 10,000 vehicles, less than 600 remain in the reserves of a number of countries.
During exploitation of the BTR-40 armoured personnel carrier by the Soviet Army it became apparent that the inability to cross water obstacles was a substantial problem on the modern battlefield. As a result in late 1954 work, led by designer V. K. Rubtsov, began at the A. Dedkov OKB design bureau on a new amphibious version of the vehicle. Intended simply to be an amphibious variant of the BTR-40 wheeled APC, it received the designation BTR-40P.
The design reused many components from the BTR-40, but as work progressed the design concept changed. The vehicle ended up being an amphibious armoured scout car. Consequently the vehicle was renamed to BRDM which was an acronym for Boyevaya Razvedyvatelnaya Dozornaya Mashina. The first prototype vehicle was completed in February 1956. Detailed trials were conducted in the Black Sea area, and it was accepted in service in 1957 with production beginning that year.
The vehicle's most unique feature are the four additional chain-driven belly wheels, which are lowered by the driver to allow trench crossing. The vehicle also has a tire pressure regulation system which later became standard in Soviet wheeled military vehicles. The initial version of the vehicle, the BRDM obr. 1957, had an open roof, but the next production model, the BRDM obr. 1958, added a roof with twin hatches over commander's and driver's station and two hatches at the rear.
The vehicle is a conventional 4x4 design, with a welded steel chassis, an engine at the front and crew compartment at the rear. The driver sits on the left, with the commander to his right. The vehicle is not fitted with an NBC system, and has no night-vision equipment by default. The vehicle has four infra-red driving lights and a single white light searchlight is mounted on the drivers side of the vehicle. When in combat BRDM-1's front windscreens are protected by armoured shutters with integral vision blocks. When the shutters are in their open position they protect driver and commander from being blinded by the sunlight and ensure that the windscreens won't be obscured by rain or snow. The GAZ-40PB V-8 gasoline engine is based on a US Dodge truck engine, and is coupled to a manual gearbox with four forward gears and one reverse with a single dry-plate clutch. The four additional belly wheels which can be lowered to improve the vehicles cross-country performance by reducing its ground pressure, and to allow it to cross trenches up to 1.2 meters wide. Tire pressure in the main tires can also be raised and lowered by the driver for better performance.
The vehicle is fully amphibious, a trim board is raised at the front of the vehicle before entering the water to improve vehicle's stability and displacement in water and prevent the water from flooding the bow. In the water the vehicle is propelled by a single rear-mounted water-jet. The water jet is powered by the main engine which drives a four-bladed propeller. The water jet outlet is protected by an armoured shutter while on land. This shutter must be removed before entering water. While the trim board in the front is in its travelling position it serves as additional armour.
The BRDM-1 has maximum armour thickness of ten millimeters which provides it with protection against small arms fire and small shell fragments but doesn't protect it against larger artillery fragments and a .50-calibre machine gun fire. The BRDM-1-series tires are not protected by armour. They are particularly vulnerable to puncture from fire of all kinds. The BRDM obr. 1959 was normally armed with a single 7.62 mm SGMB medium machine gun mounted at the front of the hull for which 1,250 rounds of ammunition were carried. The BRDM-2 obr. 1960 also had mountings for two more 7.62 mm SGMB medium machine guns on the sides of the roof however usually only one machine gun was mounted even though it was possible to mount machine guns in all three mounting points. Later the 12.7 mm DShK 1938/46 heavy machine gun or 14.5 mm KPV heavy machine gun replaced the 7.62 mm SGMB medium machine gun in the front while an additional 7.62 mm SGMB medium machine gun was mounted on the rear. It was still possible to mount the other two 7.62 mm SGMB medium machine guns on the sides of the vehicle.
The Soviet Army however disliked the vehicle for several reasons. The vehicle had no turret and to operate the armament the gunner had to open a hatch and expose himself to enemy fire. The vehicle also didn't have any kind of special sights which undermined its usability as a reconnaissance vehicle. These drawbacks encouraged the design team to create a new vehicle which would suit modern battlefield.