BMP-1 with turbine track blades

One of the effective ways to improve the amphibious capabilities of a tracked propulsion system is to equip it with so‑called turbine blades. The leading edges of the blades face inward toward the track loop, and the trailing edges face the ground, which means they must not protrude beyond the supporting surface of the track. When the track rotates in water, the profiled surface of the blades generates hydrodynamic lift and horizontal thrust, the projection of which provides additional traction force.

Such a propulsion system was used in the early 1950s on the American LVTP‑5 vehicle, which demonstrated very high water speed (11.2 km/h) with an 18.9 kW/t (25.7 hp/t) power-to-weight ratio. This speed was achieved thanks to the large width of the turbine blades located in the middle part of the track links.

The principle of turbine blades can also be implemented, as done on the tracks of the Swedish IKV‑91 light tank, where small turbine blades were placed on both sides of the track, providing swimming speeds up to 8 km/h with a 20 hp/t power-to-weight ratio.

For comparison, the BMP‑1 with conventional tracks required a higher power output to reach 7.8 km/h, and additional measures were needed, such as installing a watertight casing, which worsened land‑operation conditions.

The track-mounted turbine blades were made of shaped plates measuring 70 mm wide and 160 mm long. The blades were mounted at a 44° angle. Various mounting configurations were tested: an intended layout of 84 blades (on every other track link) and 42 blades (mounted on every 2nd track link). In order to accommodate the new modification, the sideskirts and rear fenders had to be widened.

The vertical axis represents two variables: V km/h represents the nominal vehicle speed, and Рш/kN represents hydrostatic forces exerted by the tracks. 

The horizontal axis represents two variables: Vг,km/h represents track movement speed relative to the engine RPMs in 3rd gear.  

Line 1 and 4 - Standard BMP-1 track layout 

Line 2 and 5 - 42-blade layout 

Line 3 - 84-blade layout 

Based on the tested mounting layouts, the following results were achieved: 

At a steady track movement speed of 18km/h the 84-blade layout increases the vehicle's amphibious speed by 1,8-2,0km/h, while the 42-blade layout provides a speed increase of 1,5-1,8km/h. The exerted hydrodynamic force of the 42-blade layout is almost double that of the standard BMP-1's track metric. At a track speed of 27km/h the exerted force is roughly 14 kN, bringing this performance metric close to the PT-76's waterjet performance. 

Another improved metric is the amphibious turn rate. The 42-blade layout increased the traverse speed from 7°/sec to 10°/sec, resulting in an approximate 22-26% turn speed increase. 

Taken from: 

1. Вестник бронетанковой техники, № 1, 1980 - Гусеничный движитель с турбинными лопатками