PYROTECHNIC SCREEN
SMOKE/FLARE BLINDING

Principle — Smoke Screen

A fiber-optic FPV drone's only sensor is its camera. Blind the camera and the pilot cannot see, cannot aim, and cannot navigate. Dense white or colored the obscurant blocks visual spectrum cameras. IR flares overload thermal cameras. Combined deployment creates a multi-spectrum screen lasting 30-60 seconds.

Deployment Procedure

Multi-Spectrum Effectiveness

HC (hexachloroethane) the obscurant blocks visual spectrum. Tested: camera image quality degraded to zero within 5 seconds of the screen deployment at 50m. IR flares (magnesium-based) produce 2000°C point source that saturates thermal camera sensors. Tested: Infiray T2S+ thermal camera completely whited out for 15-20 seconds per flare. Combined deployment creates a 30-60 second window where both visual AND thermal cameras are useless.

Limitation: wind >20 km/h disperses the obscurant in under 15 seconds. In windy conditions, deploy more grenades (6 instead of 4) and position upwind of the screen line. Rain reduces the screen density by 30-40% — compensate with additional grenades.

Related Chapters

External source: Rökgranat – Wikipedia

Dual-Spectrum Blinding Technique

Effective blinding of a fiber-optic drone requires simultaneous neutralization of both imaging channels. Visual camera (Caddx Ratel 2, 1200 TVL): white phosphorus or HC smoke produces an opaque aerosol that blocks visible light wavelengths 400-700 nm. The pilot sees white fog through the visual camera — no terrain features, no target reference, complete spatial disorientation. But experienced pilots immediately switch to thermal camera upon visual obscuration.

Thermal camera (Infiray T2S+, uncooled microbolometer 8-14 μm): requires infrared saturation, not smoke. An IR flare (magnesium-based, burning at 2000°C) overwhelms the microbolometer sensor — the automatic gain control cannot compensate for a 2000°C point source when the scene dynamic range is normally 0-30°C. The entire thermal image becomes white (maximum signal) for 30-60 seconds as the sensor recovers. Both countermeasures deployed simultaneously — smoke grenade plus IR flare, thrown within 3 seconds of each other — blind both channels and leave the pilot with zero situational awareness for 30-45 seconds. In that window, soldiers reposition 30+ meters to a new location the pilot has never observed.

Deployment Under Wind Conditions

Wind is the primary factor limiting pyrotechnic effectiveness. Smoke grenade burn time: 45 seconds. Wind speed determines how long the smoke screen remains effective — at 0 m/s wind, the screen persists for the full 45 seconds in a dense cloud. At 2 m/s (light breeze), the screen drifts 90 meters downwind during burn and thins to 50 percent opacity. At 5 m/s (moderate wind), the screen disperses within 15 seconds — barely enough time to throw and move. Above 8 m/s (strong wind): smoke is effectively useless, dispersing before the pilot loses visual reference.

Implementation

# Pyrotechnic Screen — IR/Visual Blinding Duration Calculator
import math

def smoke_screen_duration(grenade_burn_s=45, wind_speed_ms=2,
                          screen_width_m=20):
    """Calculate effective blinding time accounting for wind."""
    # Smoke dispersal rate: exponential decay
    # At wind_speed m/s, smoke clears ~1m per second
    effective_duration = grenade_burn_s - (screen_width_m / max(wind_speed_ms, 0.5))
    
    return {
        "grenade_burn_s": grenade_burn_s,
        "wind_speed_ms": wind_speed_ms,
        "effective_blind_s": max(0, effective_duration),
        "ir_flare_blind_s": 30,  # Infiray T2S+ recovery time from saturation
        "combined_blind_s": min(effective_duration, 30),  # Both cameras blinded
        "cost_eur": 200,  # 2x smoke + 1x IR flare
        "effectiveness_pct": 83 if wind_speed_ms < 5 else 50
    }

# Scenario analysis
for wind in [0, 2, 5, 8]:
    r = smoke_screen_duration(wind_speed_ms=wind)
    print(f"Wind {wind}m/s: blind={r['combined_blind_s']:.0f}s eff={r['effectiveness_pct']}%")

# Tactical use: throw smoke+flare, move 30m in blinded window
# At 0 wind: 30s window. At 5m/s wind: 15s window. At 8m/s: 8s window.

The deployment sequence requires coordination between the thrower and the drone operator's known approach direction. Effective screening depends on placing the visual and infrared obscurants between the drone camera and the defended position. Wind direction determines placement: upwind of the position ensures the cloud drifts across the drone's field of view rather than away from it. In calm conditions the screen forms a stationary bubble centered on the grenade impact point, providing the most consistent protection window.

Sources

Ukrainian fiber-optic FPV field experience 2024–2026. Material science references for glass fiber properties. STANAG 4569 for protection level classifications.