Course: Unmanned Aerospace Systems Operations and Payloads
Aircraft design is often driven by elements such as specified mission capabilities, performance characteristics, and derived requirements. It has been characterized by a relentless pursue of innovation, continuous improvement, and safety. These general tendencies observed throughout the design of manned aircraft can also be noticed with the development of Unmanned Aerial Systems (UAS). Enabling flight requires a reliable launch procedure and retrieving the flying vehicle necessitates a dependable recovery method. The simplest and most cost-effective launch and recovery methods for large UAS are wheeled take-off and landing (Atkins, Ollero & Tsourdos, 2017). This is exhibited by the General Atomic Predator C Avenger. What are the characteristics, advantages and disadvantages of the Avenger’s launch and recovery method?
The Predator C Avenger is an advanced Unmanned Combat Aerial Vehicle (UCAV) that is reportedly built for Intelligence, Surveillance and Reconnaissance (ISR) and precision strikes. The system exhibits optimum maximum speed and endurance capabilities (General Atomics, 2021). It is a fixed wing UCAV that is characterized by a wingspan of 20 m, a length of 13 m, and a maximum take-off weight of 8255 kg . It is powered by the Pratt and Whitney PW545B Turbofan and equipped with a 3-wheel landing gear system to accommodate launch and recovery (General Atomics, 2021).
The Avenger takes flight through a conventional take-off which is enabled by a 3 wheel landing gear system. It requires a runway or designated smooth area, thrust produced by the aircraft engine and a sudden acceleration of the vehicle until it reaches flight speed and the minimum lift required for take-off is generated. A critical parameter for conventional lift-offs is the minimum take-off distance. This parameter depends on system characteristics like total weight and wing area. The ambient density will also affect the minimum take-off distance (Anderson, 2016). ATA Chapter 32 provide further details on components of a landing gear system (Fielding, 1999). Although it is technically specific to commercial aircraft, it provides a significant reference for UCAVS. Landing gear systems are generally composed of a main gear (tailwheels) and doors, a nose gear (nosewheel) and doors, wheels and brake, position and warning sensors, a ground safety switch, supplementary gear like skis and floats, and mechanisms for extension, retraction, and steering (Fielding, 1999).
The Avenger recovery method constitute of a horizontal landing enabled by a its 3 wheeled landing gear system. This requires the aircraft to decrease power and thrust and descend from the air to the runway. The aircraft must then decelerate on the runway until it reaches a complete stop. The ground roll typically requires the application of system brakes and the use of flight control surfaces like flaps to decrease power and spoilers to decrease lift. Although specific system details were unavailable, the fact that it is equipped with a rather sizeable turbofan indicate that the aircraft shall possibly be equipped with a thrust reverser mechanism for deceleration during the ground roll (Anderson, 2016). It is important to note that a UAV control system and flight management system also contribute to systems launch and recovery (Valavanis & Vachtsevanos, 2014).
The advantages of Conventional Take-off and Landing (CTOL) is simplicity, familiarity, and cost-efficiency. It does not require significant innovations or the development of a complex new system hardware (Fahlstrom& Gleason, 2012). Wheeled systems are extremely reliable and provide the means for a well-balanced system to support the aircraft weight and components. The disadvantages of CTOL include an increase in overall system weight and the need for a landing site which often require significant preparation and coordination activities. It also requires a flight control and management system that enables and support take-off and landings. (Fahlstrom& Gleason, 2012).
Reference
Anderson, J.D. (2016). Introduction to Flight. New-York, NY: McGraw-Hill Education
Atkins, E., Ollero, A., & Tsourdos, A. (2017). Unmanned Aircraft Systems. ProQuest
Fahlstrom, P., & Gleason, T. (2012). Introduction to UAV Systems. ProQuest Ebook
Fielding J. P. (1999). Introduction to Aircraft Design. Cambridge University Press: Cambridge,
United Kingdom
General Atomics. (2021). Predator C Avenger. Retrieved from
Valavanis, K. P., & Vachtsevanos, G. J. (2014). Handbook of unmanned aerial vehicles
(1st 2015. ed.). Springer Reference.
Comments