The Design, Development and Testing of the CL-227 Unmanned Air Vehicle (Sentinel and Sea Sentinel)

The CL-227 is an advanced coaxial rotary wing vertical launch and recovery unmanned air vehicle (UAV) system which was conceived for surveillance and target acquisition. Standing 5.8 feet (1.77 meters) tall, powered by a gas turbine engine, the CL-227 air vehicle can reach speeds of up to 80 mph (130 km/hr) and can remain airborne for over 3 hours. This article summarizes the history and evolution of the CL-227 from its CL-84 tilt-wing aircraft origins through recent at-sea deployments using an autoland system. The Phase I vehicle development is discussed in some detail. System composition are discussed as well as the vehicle evolution. Wind tunnel results at the National Aeronautical Establishment (Ottawa) are presented as well as the preliminary tethered flight tests leading up to the first free flights. Emphasis is given to the maritime environment (offering the greatest challenge). The test plan and results of shipboard demonstrations are discussed highlighting system dynamic and mission performance. Considerable portion of the discussion concentrates on the USNavy shipboard deployments termed the Maritime VTOL UAV System (MAVUS) programs (I and II). The devices employed to recover the CL227 on ship automatically are discussed. Discussion is provided on the Common Automatic Recovery System which provided precision tracking and control for the recovery operation. Tethered and along-side flight testing results of the automatic recovery system are presented.