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Command and Control
Published in R. Kurt Barnhart, Douglas M. Marshall, Eric J. Shappee, Introduction to Unmanned Aircraft Systems, 2021
While systems are fairly straightforward for small unmanned aircraft, launch and recovery becomes quite complex for larger systems. Besides having the automatic takeoff and landing systems integrated into the autopilot system itself, large unmanned aircraft sometimes have separate dedicated systems to handle this. These usually interface with the autopilot system, and are called automatic launch and recovery ALR systems. Some employ RTK GPS for precision landing. These systems may land the aircraft autonomously in the event of a communications system failure. An equipped aircraft sometimes includes a special transponder that a tracking system near the landing area locks onto. This is especially useful for approaches in high-dynamic landing situations such as shipboard operations and during hostile weather. Other ALS systems are primarily optically based, employing dual camera systems for landing terrain and precise target object tracking.
Lessons from the Hudson
Published in Erik Hollnagel, Jean Pariès, David Woods, John Wreathall, Resilience Engineering in Practice, 2017
While the notion is not commonly used in aviation safety language, one could recognise behind this hierarchy of responses a compact version of a classical ‘defence-in-depth’ strategy. For example, concerning bird hazard, the first line of defence is minimising the frequency of bird strikes. The second is the ability of the aircraft and its engines to hit some birds without damage. The third is the ability of the crew-aircraft system to continue flying and to reach a (possibly alternate) airport after impacting birds and losing one engine. The fourth is the ability of the crew-aircraft system to keep enough flight controllability after losing all engines to be able to glide towards a runway or any suitable crash-landing area. The last line of defence is the ability of the crew-aircraft system to land on unprepared terrain or ditch with minimum damage and to safely evacuate passengers.
Command and Control
Published in Douglas M. Marshall, R. Kurt Barnhart, Eric Shappee, Michael Most, Introduction to Unmanned Aircraft Systems, 2016
Besides having the automatic takeoff and landing systems integrated into the autopilot system itself, large unmanned aircraft sometimes have separate dedicated systems to handle this. These usually interface with the autopilot system, and are called automatic launch and recovery (ALR) systems. Again, some employ RTK GPS for precision landing. These systems may land the aircraft autonomously in the event of a communications system failure. An equipped aircraft sometimes includes a special transponder that a tracking system near the landing area locks onto. This is especially useful for approaches in high-dynamic landing situations such as shipboard operations and during adverse weather conditions. Other ALS systems are primarily optical-based, employing dual camera systems for landing terrain/precise target object tracking.
Failure Progression of Spur Gears during a Simulated Loss-of-Lubrication Event in a Rotorcraft Drive System
Published in Tribology Transactions, 2020
Kevin Radil, Stephen Berkebile
To address LoL, the Army requires all rotorcraft MRGBs to be capable of operating at minimum power during a LoL event for up to 30 min to provide adequate time for the pilot to maneuver the aircraft to a safe landing area (5). To meet this difficult but important mandate, rotorcraft manufacturers allocate a great deal of time and money to designing and developing strategies that will enable their MRGBs to operate without oil. Past strategies include designing reservoirs into the housings to store and drip feed oil to vital components (gears, bearings), oil wicks, and auxiliary lubrication systems. Additionally, thermal loading has been addressed by designing gearboxes with minimal gear meshes, larger gears for greater thermal absorption, and increased backlash (6). At this time, a popular solution to meeting LoL requirements is the installation of an auxiliary lubrication system, which is the most effective and reliable. However, this adds weight and complexity to the aircraft and increases maintenance and logistics costs. With a reduction in aircraft weight as a continued objective of the Army, designing more inherently robust MRGBs for LoL would eliminate the need for auxiliary lubrication systems and its associated penalties without sacrificing aircraft reliability and survivability.