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Background  — CF Mini-UAV  candidates —  Boeing/Insitu ScanEagle

Update DND now has a renewable lease contract with Boeing to provide contractor-supported ScanEagle SUAV (Small UAV) operations at Kandahar Airfield. With the end of CF combat operations in Afghanistan, that contract may not be renewed.  No CF designation for the leased ScanEagle was announced but a 2009 Directorate of  Flight Safety publication mentions a "CU165" –  likely a ScanEagle reference.

A Fish Story  with a 'Watchful  Eagle' In  Place
The Boeing-Insitu ScanEagle is based on a civil UAV (the SeaScan used  by commercial fishers). The ScanEagle layout  is the least conventional of CF mini-UAV candidates (the low aspect-ratio wings are swept with endplate vertical tails fitted to either tip).  The SeaScan's arrangement is not unique among UAVs –  the absense of conven- tional empennage allows for a pusher propeller – as it frees the nose for the placing of sensors. [1]

Originally, the ScanEagle followed the layout of Insitu's tuna-seeking SeaScan with its optical sensors in a clear acrylic nose-cap (right). The design has now been revised , with the sensor 'bubble' placed under the nose (allowing the military UAV to see where it has been as well as where it is going).  Like the larger Sperwer, Scan Eagle is launched by a pneumatic cata- pult (left, using a combination of cable pull and compressed air ).

Insitu Group is proud of its SuperWedge catapult but the ScanEagle distinguishes itself not during launch but in recovery. [2]  On either end of ScanEagle's 3.1m wingspan is a hook. The SkyHook Retrieval System is simply a suspended cable upon which the Scan Eagle can snag itself, catching the line with one or other of its wingtip hooks.  SkyHook works on land (using a vehicle-mounted extensible arm (right) or at sea drawing ScanEagle to the attention of the USMC and US Navy. ScanEagle deployed to Iraq in  2004 with  I-MEF and has been  tested on USN ships.

Data for ScanEagle:  wingspan 3.1m, length 1.2m, fuselage diameter 0.2m, max  takeoff weight 18kg, sensor payload 6kg, endurance 15-to- 20 hours, max speed 120 km/h, cruise speed 90 km/h, service ceiling 5000m to 5790m, camera range 100+ km, engine 3W  24i  (23 cc 1.1kW).

[1] The CF's Sperwer TUAV achieves the same benefit through its delta-winged pusher-propeller layout. But delta wings aren't especially stable at low speed (or even higher speeds, apparently: a later model, jet-powered Sperwer-HV (Haute Vitesse) has canard surfaces fitted).

[2] Many early UAVs (eg: Pioneer) recovered with nets (although the makers prefer descriptions like "energy absorbing device"). Today, parachute is the most common recovery method. But  this is poorly suited to shipboard recovery. With its sea-going heritage ScanEagle, addressed this problem from the outset. Complaining that this is a "single system" solution ,  the USN seems to prefer expendable UAVs.