Military Reconnaissance UAV

Overview

A tactical reconnaissance UAV is an unmanned fixed-wing aircraft that loiters over an area of interest for half a day at a time, streaming stabilized day and thermal imagery to a ground station up to 100 km away. The class described here, aircraft in the 150–250 kg range such as the RQ-7 Shadow, Luna NG, and Hermes 90, sits between hand-launched squad drones and the much larger MALE aircraft that need runways and satellite links. A complete system is not one aircraft but a unit: typically three or four air vehicles, one Ground Control Segment, and spares, transported on two vehicles.

Airframe and propulsion

The Airframe is built for endurance, not speed. Each Wing Panel is a foam-cored composite structure of about 17:1 aspect ratio, glider proportions, that detaches at a spar joint for transport. The Fuselage pod carries the sensor payload in the nose, fuel at the center of gravity, and the engine at the rear; twin Tail Booms carry the inverted-V Tail Surfaces past the propeller disc. Six sealed Control Surface Servos move the surfaces.

Propulsion is a rear-mounted pusher: the Heavy-Fuel Engine, a twin-cylinder fuel-injected unit of about 28 hp, burns JP-8 so the system needs no special fuel in the logistics chain. The pusher layout keeps the nose hemisphere clear for the turret and puts engine vibration behind the payload, further isolated by the elastomer Engine Mount. The two-blade composite Pusher Propeller and tuned Muffler are both chosen for acoustic signature: at loiter altitude the aircraft should be inaudible from the ground. Fuel, roughly 55 L, sits in a Fuel Bladder Tank bladder at the center of gravity, fed by a redundant Fuel Pump, so trim does not wander over a 14-hour sortie.

Sensor payload

The reason the aircraft exists is the EO/IR Sensor Turret, a gyro-stabilized ball gimbal of about 25 cm diameter under the nose. Inside the sealed Gimbal Housing, a daylight zoom Lens Assembly feeds a visible-band CMOS Image Sensor while a second objective feeds the cooled MWIR Thermal Core, a 3–5 µm mid-wave thermal imager that resolves vehicles beyond 10 km at night. A Laser Rangefinder measures slant range so any pixel the operator marks converts to a target grid reference accurate to a few meters.

Stabilization is what makes the imagery usable: two Servo Motor drives with Encoder feedback steer the gimbal in azimuth and elevation, while the Gimbal IMU on the inner stage closes a rate loop that holds line-of-sight jitter below roughly 25 µrad, fine enough to keep a narrow field-of-view image steady from a vibrating piston-engine aircraft in turbulence.

Avionics and datalink

The aircraft flies itself. The Flight Control Computer, a redundant autopilot built around a Compute SoC Module with Microcontroller monitor channels, executes waypoint navigation, holds, and the landing flare, fusing the Navigation IMU, GNSS Receiver, and Air Data Probe. The operator commands intent (orbit here, look there), not stick inputs. If the link drops, lost-link logic flies a pre-briefed route home and lands autonomously. A IFF Transponder keeps the aircraft visible to friendly air traffic control.

The Datalink (Airborne) carries a low-rate command uplink and a several-Mbit/s compressed video downlink in C-band at about 10 W, both encrypted by the Crypto Module. Two Omni Antenna blades, top and bottom, ensure the airframe never shadows the link in a bank; at long range the ground end switches to the high-gain dish on the Antenna Tracker.

Electrical power comes from the engine-driven Alternator (about 900 W at 28 V), with an eight-cell LiPo Cell pack and BMS Board as backup. On alternator failure the Power Distribution Unit unit sheds the turret and keeps only autopilot and datalink alive, preserving enough battery to glide home under control.

Ground segment and operation

The Ground Control Segment is crewed by two operators: an air vehicle operator managing the flight plan and a payload operator steering the turret from the GCS Console. Three LCD Panel displays show the moving map, the sensor feed, and aircraft telemetry; the Ground Datalink Terminal and antenna tracker close the link. Takeoff and landing use the fixed Landing Gear on a 250 m semi-prepared strip, composite Main Gear Leg springs absorb landing energy without oleo struts, and the steerable Nose Gear handles taxiing. The fixed gear costs a few knots of cruise speed, a trade accepted for mechanical simplicity and sortie-rate reliability in the field.