STRV 122
DRONE DEFENSE

Why Tanks Need Drone Protection

The Strv 122 was designed in the 1990s against threats that approached horizontally — anti-tank missiles, sabot rounds, RPGs. Its frontal composite armor defeats all of these. But FPV drones attack vertically, diving onto the turret roof where armor is thinnest. The crew cannot see a drone approaching from directly above. The 120mm main gun cannot elevate to engage a target 50 meters overhead. The coaxial machine gun has a limited elevation angle. The tank's existing weapons are geometrically unable to address the drone threat. External protection is the only solution.

Layer 1 — Detect: RSP-72 Micro-Radar

RSP-72 is a frequency-modulated continuous-wave (FMCW) radar weighing 1.2 kg, drawing 45W, mounted on the turret bustle. It detects objects with a radar cross-section as small as 0.01 m² (a typical FPV drone) at ranges up to 2 km. The radar operates in all weather conditions — fog, rain, snow, darkness — where acoustic and visual sensors fail. It provides range, bearing, elevation, and radial velocity. When a target enters the detection envelope, Lisa 26 L1 generates an alert: "Inbound UAV, bearing 045, range 1.8 km, closing 80 km/h." The crew sees an orange symbol on their Lisa 26 tablet. No action required yet — the system is watching.

Layer 2 — Jam: FSG-J2 Omnidirectional

At 500m range, Lisa 26 L1 activates the FSG-J2 jammer automatically. The jammer radiates across 400-1200 MHz and 2.4/5.8 GHz simultaneously, covering the frequency bands used by DJI, analog FPV, and most military control links. Effective radius: 200m centered on the tank. The jammer does NOT affect the tank's own MANET radio because Silvus StreamCaster operates at 140-600 MHz with frequency-hopping — outside the jammer's primary bands and protected by FHSS even in the overlap zone. The jammer runs continuously when the tank is in a threat area. Power consumption: 35W from the tank's 28V system — negligible compared to the APU's 6 kW output.

Layer 3 — Intercept: Dual Canister Launch

If the incoming drone survives jamming — because it uses fiber-optic control, autonomous navigation, or a frequency the jammer does not cover — Lisa 26 L3 launches an interceptor. Two interceptor drones sit in sealed canister launchers bolted to the turret bustle. Launch sequence: canister lid blows (pyrotechnic, 0.3s), motors spin to flight speed (1.2s), Lisa 26 computes intercept vector from radar track (0.5s), interceptor accelerates to target (2-6s depending on range). Total time from launch command to impact: 4-8 seconds. Single interceptor probability of hit: 80%. With two launched simultaneously on divergent approach vectors: 1 - (0.2)² = 96%. The interceptor destroys the threat by kinetic collision — no warhead, no fragmentation risk to friendly infantry nearby.

Why Not the Crew Commander's Machine Gun

The Strv 122's Ksp 58 (7.62mm) and the commander's weapon station cannot reliably engage a 25 cm wide drone traveling at 80+ km/h. Ukrainian data from 2023-2024 shows crew-operated machine gun engagement success rate against FPV drones below 5%. The problem is reaction time: a human sees the drone, identifies it as hostile, traverses the weapon, aims, and fires — 8-15 seconds minimum. An FPV drone at 80 km/h covers 180-330 meters in that time. By the time the gunner fires, the drone is already inside the lethal envelope. Automated systems react in milliseconds. This is not a criticism of crew skill — it is physics.

The Stridsvagn 122 represents Sweden's primary main battle tank and its most valuable armored asset. Protecting each Stridsvagn from drone attack costs less than 0.2 percent of the Stridsvagn's replacement value. The Stridsvagn 122 drone defense package integrates seamlessly with the existing turret electronics.

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External source: Stridsvagn 122 – Wikipedia

Implementation

# Strv 122 CUAV System Configuration — Lisa 26 Integration
# RSP-72 Radar → Lisa 26 L1 → Jammer/Interceptor chain

# RSP-72 radar parameters
RSP72_CONFIG = {
    "freq_ghz": 24.0,           # K-band FMCW
    "range_max_m": 2000,         # 2 km detection range
    "rcs_min_m2": 0.01,          # Detect 0.01 m² (small FPV)
    "update_rate_hz": 10,        # 10 scans per second
    "power_w": 45,               # Continuous power draw
    "mount": "turret_bustle",    # Fixed to turret rear
}

# Lisa 26 L1 automatic response chain
def on_radar_detection(track):
    if track.range_m > 1000:
        lisa26.alert_cop(track)          # Orange symbol on all displays
    
    if track.range_m < 500 and track.closing:
        jammer.activate()                 # FSG-J2 omnidirectional ON
        lisa26.alert_cop(track, "JAMMING ACTIVE")
    
    if track.range_m < 200 and track.still_closing:
        # Jamming failed — fiber or autonomous drone
        interceptor.launch(track)         # L3 autonomous — no human delay
        lisa26.alert_cop(track, "INTERCEPTOR LAUNCHED")

Swedish Supply Chain

Related Chapters

Sources

Swedish Armed Forces Strv 122 public data. Ukrainian tank loss analysis (Oryx, 2022-2026). RSP-72 radar datasheet. FPV engagement success rates (Ukrainian General Staff, declassified 2024).