Anti-Shahed Technology: Removable Over-Wing DEP Module for Cessna Caravan C-UAV Platform

[wcrb66]

Title: Cessna 208B ESTOL Modification with Distributed Electric Propulsion (DEP) and AESA Radar
Dear Forum Members,
I would like to present a conceptual design for a rapid ESTOL (Extremely Short Take-Off and Landing) conversion kit designed for the Cessna 208B Caravan EX. This system is engineered as a non-invasive, bolt-on modification optimized for low-speed counter-UAV (C-UAV) and maritime border patrol missions.
The primary objective is to combine the payload capacity and endurance of a rugged turboprop airframe with ultra-low-speed loitering capabilities and extremely short field performance, without altering the aircraft's primary internal structure.

1. Airframe Integration & Aerodynamics (The DEP Module)
The core of this modification is a completely removable over-wing "exoskeleton" made of conformal composite sandwich panels. It clamps onto the rigid wing box externally using self-locking latches, requiring no structural modifications to the native airframe.

• Flap & Slat Integration: Special C-shaped cutouts within the pylon fairings anatomically match the kinematic path of the original Fowler flaps and slots, ensuring full operational deflection without any mechanical interference.
• The Coanda Effect: The module features eight 30 kW electric motors driving 1.40-meter fixed-pitch propellers. These motors generate a continuous high-velocity laminar flow over the upper wing surface. By blowing the wing, the maximum lift coefficient (\(C_{y}\)) is forced up to 3.2, reducing the take-off roll to just 65.5 meters under a 4.7-second acceleration.
• Deceleration & Recovery: During landing, the electric motors instantly provide 100% maximum electric reverse thrust, achieving a landing roll of 130 meters. The primary Pratt & Whitney PT6A turboprop remains at idle during this phase, which reduces its thermal cycling and extends its Time Between Overhaul (TBO) by an estimated 30–35%.
• Regenerative Braking: During descent from a 4,000-meter patrol altitude, the propellers enter autorotation mode, acting as aerodynamic brakes. This process regenerates up to 6.5 kWh of energy back into the localized batteries at an efficiency rate of 60–65%.

2. Weight Distribution & Power Architecture
To avoid running dangerous high-voltage DC lines through the main cabin or fuselage, the power architecture is completely decentralized and self-contained within the over-wing pods:

• Dry Weight of the Kit: 358 kg (includes 8 motors, inverters, composite structure, and battery pods).
• Distributed Battery Capacity: 11.2 kWh divided into local buffer modules located directly inside the over-wing engine pylons.
• Aircraft MTOW: 3,200 kg.
• Radar Payload Weight: ~30 kg.

3. Mission Payload & Tactical Capabilities (C-UAV Application)
The modification transforms the aircraft into an airborne early warning and control (AEW&C) platform specialized in detecting low-altitude, low-RCS threats in complex terrain or over water:

• Ultra-Low-Speed Loitering: Due to the continuous wing-blowing effect, the aircraft maintains stable, controllable flight at speeds as low as 110–120 km/h without risking a stall. This low speed expands the integration window for Doppler signal processing, allowing the radar to filter out ground clutter more effectively.
• Radar Performance: An AESA radar (such as the Leonardo Osprey 30 or RPS42 flat panels) is integrated into a low-drag composite over-fuselage fairing. Operating from a 4,000-meter ceiling, it bypasses the radar horizon constraints of ground-based air defense, detecting low-flying UAVs (with an RCS of ≈ 0.1 m², typical for Shahed-class loitering munitions) at ranges of 110–130 km.
• Active-Passive Cooperative Interception: The concept envisions operating these platforms in synchronized pairs. Every 30 seconds, the aircraft alternate roles between active transmission and passive reception. This cooperative bistatic/multistatic processing captures lateral specular reflections from the targets, increasing their effective RCS by 10 to 15 times (up to 1.5–2 m²). Furthermore, this alternate-switching tactic disrupts the tracking algorithms of hostile anti-radiation missiles (ARMs).

Я был бы признателен за ваши инженерные замечания относительно аэродинамического взаимодействия распределенного воздушного потока от винта с задней кромкой крыла, а также по вопросам терморегулирования децентрализованных аккумуляторных блоков внутри пилонов.

 

[wcrb66]

Analogues of Conformal Add-on Modules / Retrofitting
This architectural design, where the baseline wing requires no drilling or permanent modification but is instead "clasped" by a ready-made removable package, has precedents in both the military sector and patent literature:

• Conformal Fuel Tanks (CFTs) and Wing Pods: Fighter aircraft (such as the F-15E Strike Eagle and Eurofighter Typhoon) utilize conformal fuel tanks and electronic warfare pods that tightly conform to the fuselage or wing contours without altering the underlying load-bearing spar structure, securing instead to standard hardpoints.
• Patent US12240634B1 (Mission-adaptable aerial vehicle and methods for in-field modification): A cutting-edge patent (2026) describing modular modification of aircraft performance characteristics in field conditions. It allows an operator to augment the baseline wing with removable over-wing modules (in-wing pods / external sections), swapping the vehicle's propulsion system right before a mission to increase lift or operational range.

 

[wcrb66]

Project Abstract (English Version)
Title: Universal Conformal Coanda-Effect Distributed Electric Propulsion ESTOL Module
This project presents a scalable, non-invasive conformal add-on architecture designed to retrofit production airframes into Extremely Short Takeoff and Landing (ESTOL) platforms. Secured via external self-locking mechanisms without wing skin penetration (0:28), the module features deep C-shaped cutout arches that allow baseline high-lift devices to actuate unobstructed (0:37). Propulsion is driven by a capsular distributed energy architecture, encapsulating isolated 150 kW motors, inverters, and buffer batteries within individual rigid pylons to eliminate fuselage-routed high-voltage cabling (1:08).
By generating a high-velocity parallel flow over the wing extrados, the system leverages the Coanda effect to drastically accelerate lift coefficients, reducing takeoff ground roll four-fold (e.g., down to 462 m for a 75-ton airliner) (2:59). During cruise, two-blade propellers fold flush to achieve zero drag (1:46). During descent, they switch to a windmilling autorotation regime, acting as aerodynamic disc brakes and harvesting clean energy back into the localized batteries with a 60–65% efficiency (3:27). Upon touchdown, immediate 100% reverse thrust ensures ultra-short landing rolls (4:04). The system is engineered across three scaling dimensions: mainline jet airliners (Boeing 737) (4:22), regional/utility utility platforms (Cessna Caravan) with integrated AESA radar, and UAV carrier launch platforms for cargo gliders.