The BM-8-24 was a rather simplistic conversion of Soviet Army T-40 and T-60 light tanks to serve as rocket launcher carriers during World War 2. Once the tactical usefulness of the vehicles as direct-combat tanks was over (and eventually replaced by the arrival of the T-34 Medium Tank line), and to shore up stocks of rocket-projecting platforms, the tank hulls were selected for quick conversion in which their hulls, drivetrain, and general design remained unchanged and rocket launching hardware was added over the hull in place of the standard turret and its applicable main gun armament.
The Soviets went on to heavily favor rocket launcher carriers throughout the war in their march to Berlin and this was exemplified best by the classic "Katyusha" 6x6 wheeled trucks in the role. Reuse of the light tank chassis simply made the weapon system a tracked variant and, logistically, a very sound solution in both terms of manufacturing cost and availability. Additionally, performance specifications could remain largely unchanged, providing the needed cross-country, mechanized travel capability inherent in the compact tank designs when keeping up with the main fighting force.
The 82mm rockets used in the vehicles were officially designated as "BM-8" and they were adopted in August of 1941. The T-40 and T-60 light tanks converted for the rocket projecting role were then designated collectively as "BM-8-24". The "BM" in their designation marked them as ground-based, rocket projecting vehicles while the "8" marked the model of rocket in use ("BM-8"). "24" was used to signify the number of launch rails installed on the launcher component - this numbering twenty-four in all.
While not wholly accurate individually, the rockets generated tremendous saturation effect on a target area, particularly if multiple vehicles were used in launching several salvos. Not only were they a damaging component to infantry, dug in forces, and light vehicles, they provided a detrimental psychological effect on the receiver. Projectors could be used in unison with artillery support prior to a major offensive to help "soften up" enemy positions.
Conversions of T-40 tanks to rocket launcher carriers were handled from July to September of 1941 at the Kompressor plant in Moscow and some forty-four vehicles were converted for the role. T-60s were also converted during 1941.