UAS Integration into the NAS

Next Generation Air Transportation System (NextGen) is the transformation of the US national air transportation system to alleviate the current congestion in the air and airports and in anticipation of the demands on the national air transportation system in the future. The US Congress enacted NextGen in 2003 under President Bush, creating the Joint Planning and Development Office (JPDO) to manage the different agencies partnering to design and develop NextGen. The partnerships include private sector organizations, academia, and government agencies such as the Departments of Transportation, Commerce, Defense, and Homeland Security, as well as the Federal Aviation Administration, NASA, and the Offices of Science and Technology Policy and Director of National Intelligence. The goals of NextGen are to develop new technologies while leveraging legacy technologies to support the transformation; to create capabilities and the highly interdependent technologies that will change the operations of the air transportation system, reduce traffic and passenger congestion, and improve overall flying experience (Fact Sheet – NextGen, 2014).

NextGen programs include the Automatic Dependent Surveillance Broadcast (ADS-B), System Wide Information management (SWIM), NextGen Data Communications, NextGen Network Enabled Weather, and NAS Voice Switch. ADS-B is the backbone of the NextGen system, currently in use and will be required on all commercial and GA aircraft by the year 2020, it takes the sense and avoid capabilities of aircraft to the next level (Automatic Dependent Surveillance-Broadcast (ADS-B), 2014). ADS-B can significantly enhance UAS’ ability to detect, sense, and avoid other aircraft on the grid. Other benefits of NextGen technology include: “trajectory based operations allow pilots and dispatchers to select their own efficient flight paths instead of following the existing “interstate in the sky” type routs;” a collaborative air traffic management system between air traffic managers and flight operators; reduced weather impacts through information sharing, improved weather forecasting; higher density airports through new and improved surface movement with reduced spacing and separation requirements; and allowing flexibility in terminals and airports allowing increase in throughput by uncovering previously untapped system capacity (Fact Sheet – NextGen, 2014).

However, this technology comes at a cost and may not be applicable to all UAV categories at the moment. The equipment necessary to utilize ADS-B adds weight and power demands on the air vehicle. While these requirements may be negligible on medium range to MALE/HALE UAV designs, they are of note when incorporating into smaller unmanned platforms where space, weight, and power are at a premium. The effect of the additional demands on the system comes into consideration compared to endurance or payload capacity.

            Additionally, while NextGen technology paves the way for increase integration of UAS into the MAS UAS operators will still play a big role to prevent collisions with manned aircraft. As UAS pilots they must maintain situational awareness of their aircraft and also perform analogous air traffic control (ATC) functions in conjunction with other operators to maintain separation in segregated airspace. In non-segregated airspace, UAS operators must comply with local ATC instructions if they are to operate safely within the vicinity of commercial and general aviation aircraft. NextGen aims to provide a comprehensive solution for all involved to maintain a high level of reliability and safety.

In looking towards integration of UAS into the NAS, the US Air Force issued a request for information to technology vendors to build sense and avoid systems for its drones, called the Common-Airborne Sense and Avoid (C-ABSAA) Program (Cooney, 2013). The AF seeks alternatives to the Certificate of Authorization process to increase its mission options as military and commercial use of UASs expands. This, however, only addresses one issue of the many facing UAV integration into the NAS to include ensuring reliable command, control, and communications, failsafe actions in loss-link situations, network security and anti-jamming or anti-spoofing capabilities, and interference issues in saturated RF spectrum.

 

Reference

Cooney, M. (2013, September 23). Air Force wants technology that will let drones sense and avoid other aircraft. Retrieved from Network World: http://www.networkworld.com/article/2225425/security/air-force-wants-technology-that-will-let-drones-sense-and-avoid-other-aircraft.html

Fact Sheet – NextGen. (2014, June 17). Retrieved from FAA: http://www.faa.gov/news/fact_sheets/news_story.cfm?newsid=8145

 

AeroVironment Ground Control Station

      AeroVironment, Inc. (AV) develops and manufactures scores of unmanned aircraft and electric vehicle solutions. Amongst its family of unmanned aircraft systems (UAS) is a line of small UAS widely used in support of the war effort in Iraq and Afghanistan; these ruggedized, compact, and portable UAS provide excellent intelligence, surveillance, and reconnaissance (ISR) coverage in the battlefield while gaining popularity in civil applications (Imagination, Passion, and Persistence, 2014).
               

     All AV small UAS such as the Raven, Puma, Wasp, and Dragon Eye are controlled by a common ground control station (GCS) which provides the command and control (C2), communications, data and video link to the air vehicle. AV’s GCS is a small, lightweight, compact, dustproof, waterproof, and battle-tested GCS capable of displaying real time video capture from the air vehicle payload cameras. Operators are able to capture screen images, store, playback, and re-transmit video and metadata on the network. The GCS can be used as a remote video terminal (RVT) at remote command centers providing the same capabilities as the operator’s GCS. Capable of manual and autonomous C2 the AV GCS components fit in a small sack and take only a small portion of a typical small backpack (GCS - Joint Common Interoperable Ground Control Station, 2014).


Other features of the AV common GCS include:

• An intuitive user interface built on the company’s proprietary core operating system
• Storage for up to 80 image  captures and multiple preprogrammed missions
• Ability to operate as a remote video terminal
• Manual, Altitude-Hold, Navigate, Loiter, Home, Loss-of-Link, Follow Me, and Auto land modes of operation
• Operates on common military BA-5590/U (or similar) battery
• Has a fully-packaged weight of only 7.42 pounds
• Available options include a Panasonic Toughbook laptop, Falcon view software,  and an RVT Kit Antenna

                Although a single operator can work the AV GCS, a two-person team is more ideal and is the preferred mode of operation. A study at the Army Research Laboratory on Raven operations found that GCS operators are subject to high workloads in a typical 40-45 minute mission (Pomranky, 2006). Task saturation can lead to a loss in situational awareness. Manning, Rash, LeDuc, Noback, and McKeon (2004) states that a loss in situational awareness is a leading causal factor in aviation mishaps.  The same advantages which make the GCS a popular military tactical gear, such as its portability and small design, may also cause conditions which can be detrimental to maintaining situational awareness. The vehicle operator uses a handheld controller about the size of a typical seven inch tablet computer with user control and input buttons and knobs on either side of the screen. It lacks a map display (maps are resident on the Toughbook computer) which is invaluable in determining the air vehicle’s location. This is where multiple operators become valuable; mission tasks can be tackled more effectively when divided between two operators – one to operate the hand controller and the other to program and monitor the mission on the laptop.
                Also, because of its small screen size, the hand controller display contains a significant amount of flight information that can overwhelm the operator. Add to that the need for a hood to shroud the screen from bright sunlight and give the operator a better viewing experience. This may cause some disorientation when switching from a hooded view, causing a loss in situational awareness for a few seconds while the operator’s vision recovers in transition.
                Task saturation and issues with multifunction display and control systems’ design are common to manned aircraft and AV’s small UAS mentioned above. Both human factors can adversely affect the operator’s performance which may lead to a mishap.

Reference

GCS - Joint Common Interoperable Ground Control Station. (2014, June 10). Retrieved from AeroVironment, Inc.: http://www.avinc.com/downloads/AV_GCS_V10109.pdf

Imagination, Passion, and Persistence. (2014, June 10). Retrieved from AeroVironment, Inc.: http://www.avinc.com/

Manning, S., Rash, C., LeDuc, P., Noback, R., & McKeon, J. (2004). The Role of Human Causal Factors in U.S. Army Unmanned Aerial Vehicle Accidents. U.S. Army Aeromedical Research Laboratory.

Pomranky, R. (2006). Human Robotics Interaction Army Tehcnology Objective Raven Small Unmanned Aerial Vehicle Task Analysis and Modeling. Army Research Laboratory.

The Case Analysis Approach

 

As a final paper requirement for Embry-Riddle Aeronautical University's ASCI 530 course we used the case analysis method to address an issue or a problem relating to Unmanned Aerial Systems. Using the case analysis approach to complement the coursework enhances our comprehension of the topics we learned by applying them to existing, real time situations or issues within or outside the aviation industry to help in analyzing the problem, offering alternative solutions, and making recommendations to address the problem. As students our role in the case analysis work is to diagnose and size up the situation described in the case and then to recommend appropriate action steps. The primary objectives of the case analysis approach is to increase understanding of what should or should not work to achieve success, develop skills in organizational strengths and weaknesses assessment, practice conducting strategic analysis, evaluating alternatives, and preparing plans of action applicable in any environment, and to enhance the sense of judgment by exposure to different businesses and industries. The case analysis approach is a decision making and problem-solving tool used to thoroughly evaluate a problem or issue. It evaluates the cause, the potential consequences if no action is taken, the urgency of the situation and the priority of action, identifies solution alternatives, and establishes the reasoning behind the suggested or recommended action (Case Analysis Guidelines, 2014).

The military uses a case analysis approach called the Military Decision Making Process (MDMP). MDMP is an established and proven analytical process used in many aspects of military operations from training in peace time to war time situations. MDMP is an adaptation of the Army’s s analytical approach to problem solving typically used by commanders and staff in developing estimations and plans. The full MDMP is a time consuming, detailed, deliberate, and sequential process normally employed when ample time and adequate staff is available to thoroughly examine all courses of action. Its fundamentals, however, is essential for use in time-inhibited situations. Akin to the case analysis approach, MDMP analyzes multiple courses of action to identify the best solution; it creates integration, coordination, and synchronization for an operation and minimizes the risk of overlooking a critical aspect of the operation; and it results in a detailed operation order or operation plan endorsed as a consequence of the commander’s informed decision (Military Decision Making Process and Rehearsals Tool Kit, 2012).

Both the case analysis and MDMP approach is time-consuming and better suited for team or group work. Perhaps better results are possible if the final case analysis project for this course is assigned as a group project where members of the group can collaborate and exchange ideas derived from their multiple perspectives, opinions, and experiences resulting in a far superior end product. This is, in essence, the goal of the case analysis approach.

 

Reference

Case Analysis Guidelines. (2014, May 20). Retrieved from Embry-Riddle Aeronautical University Worldwide: https://erau.blackboard.com/bbcswebdav/pid-14470955-dt-content-rid-76772571_4/institution/Worldwide_Online/ASCI_GR_Courses/ASCI_530/From_Developer/ASCI_530_Case_Analysis%20Guidelines_Version4.pdf

Military Decision Making Process and Rehearsals Tool Kit. (2012, July 5). Retrieved from Stand-To!: http://www.army.mil/standto/archive/issue.php?issue=2012-07-05

HADR UAS

Humanitarian Assistance Disaster Recovery

In November 2013 Super Typhoon Haiyan ravaged several Philippine islands leaving 10,000 dead and displacing over 600,000 people in its wake. Haiyan’s destruction left survivors with no food, water or medicine. Relief operations were hampered because roads, airports and bridges had been destroyed or were covered in wreckage. An outpouring of support from many countries and agencies converged to help the victims but food and other aid were delayed because of the conditions (Mogato & Ong, 2013). In situations like this a cost-effective way of assessing the damage and surveying potential routes or avenues of approach for relief workers can be achieved through the use of man-portable unmanned aerial system (UAS). This request for proposal lays out the requirements for a small UAS to perform on-demand aerial surveillance. Timeline for system development is six months, ideally to have a low-rate initial production in time for typhoon season.

High Level Requirements

The UAS shall be transportable in a hardened transit case weighing no more than 50 lbs.; shall cost less than $100,000; shall be capable of flight up to 500 feet altitude above ground level (AGL) ; shall be capable of sustained flight (at loiter speed) in excess of one hour; shall be capable of covering an operational radius of one mile; shall be deployable and on station (i.e., in air over mission area) in less than 15 minutes; shall be capable of manual and autonomous operation; shall provide capture of telemetry, including altitude, magnetic heading, latitude/longitude; position, and orientation (i.e., pitch, roll, and yaw); shall provide power to payload, telemetry sensors, and data-link; shall provide capability to orbit (i.e., fly in circular pattern around) or hover over an object of interest .

Major Base Requirements and Derived Requirements

           

            Three major base requirements for this project are: transportability of the entire system, the air vehicle, and the payload. The transit case design will use hardened plastic material capable of withstanding drops from at least seven feet high, preferably from up to 10 feet high. Transit case shall secure all system components in its own compartments to prevent damage while in transport and through normal use. The air vehicle shall be designed for hand-launch, ease of assembly and disassembly, and easy operation by one person. The payload shall be mounted on the underside of the air vehicle, on a gimbal for stability, use air vehicle power, and capable of color and infrared video transmission. Derived requirements and testing for each major base requirement are:

              1.     Transportability

1.1  Transit case, fully filled with all system equipment, shall weigh less than 50 lbs

1.2  Transit case shall contain all necessary system components

1.3  Transit case shall have secure compartments/cutouts for each component

1.4  Transit case shall be durable to withstand damage when dropped from a height of seven feet

1.5  Transit case, when properly used and secured, shall provide protection for all components contained within

2.     Air Vehicle (UAV)

2.1 The UAV shall be capable of flying up to 500 feet above ground level

2.2 The UAV shall be capable of operating in excess of one hour

2.3 The UAV shall be capable of operating at a range of four miles

2.5 The UAV shall have an assembly time of less than 15 minutes upon unpacking

2.6 The UAV shall be capable of being recharged from universal vehicle 12volt power source

3.     Payload

3.1 The payload shall be capable of color daytime video operation up to 500 feet AGL

3.2 The payload shall be capable of infrared (IR) video operation up to 500 feet AGL

3.3 The payload shall be interoperable with C2 and data-link

3.4 The payload shall use power provided by air vehicle element

4.     Testing Requirements

4.1 Transportability

4.1.1 Storage

4.1.1.1 Inspect transit case compartments are suitable for component parts

4.1.1.2 Test fit all system components in transit case compartments

4.1.1.3 Weigh fully loaded transit case; ensure weight is less than 50 lbs

4.1.2 Durability

4.1.2.1 Perform drop test from height of seven feet

4.1.2.2 Verify transit case durability to withstand seven foot drop

4.1.2.3 Inspect system components for damage

4.1.2.4 Perform drop test from height of 10 feet

4.1.2.5 Inspect transit case and system components for damage

4.2 Air Vehicle (UAV)

4.2.1 Perform load/stress tests on UAV fuselage

4.2.2 Perform load/stress tests on UAV flight control systems

4.2.3 Perform load/stress tests on UAV power plant

4.2.6 Check for overheating

4.2.7 Check for security of connectors

4.2.8 Confirm acceptable performance of radio transmission and reception

4.2.9 Confirm optimal antennae location and position

4.3 Payload

4.3.1 Perform system interoperability testing with Ground Control System

4.3.2 Test color daytime video operation (ground test)

4.3.3 Test infrared (IR) video operation (ground test)

4.3.4 Test payload operations at operating altitude and range

            This is a fast development and delivery project of a high quality system at a low investment cost. An iterative type framework development such as the Rapid Application Development (RAD) approach is appropriate for this project because the aim is to build a high quality system quickly (six months) with key emphasis on fulfilling a business need. Risks are reduced by breaking the project into smaller segments and providing more ease of change during development. Subsystem design and development of the air vehicle, payload, power plant, GCS, and peripherals such as transit case can happen simultaneously. RAD is suitable for small to medium scale projects of short duration with a focused scope and a well-defined and narrow business objective (Selecting A Development Approach, 2005). A sample schedule for this type of project is shown on Figure 1.

           

Reference

Mogato, M., & Ong, R. (2013, November 10). Philippines storm kills estimated 10,000, destruction hampers rescue efforts. Retrieved May 8, 2014, from Reuters: http://www.reuters.com/article/2013/11/10/us-philippines-typhoon-idUSBRE9A603Q20131110

Selecting A Development Approach. (2005, February 17). Retrieved May 8, 2014, from Centers for Medicare & Medicaid Services: http://www.cms.gov/Research-Statistics-Data-and-Systems/CMS-Information-Technology/XLC/Downloads/SelectingDevelopmentApproach.pdf

UAS Over Our Moana

Enhancing Public Safety in Hawaiian Waters with UAS

            Hawaii welcomes over seven million visitors each year who partake in many activities throughout the islands. In a five year study at the Queens Memorial Hospital researchers found that almost 23% of the 8244 admitted patients had water-related injuries. Visitors comprise only 12.6% of the population at any given day but accounts for over 44% of total admissions in hospitals for water-related injuries, “water-related injury rates are significantly higher for Hawai'i's visitors than residents” (Ho, Speck, & Kumasaki, 2009). Although the Hawaiian Government, through its Ocean Safety and Lifeguard Services Division (OS&LSD), exerts great effort in ensuring coverage of the most popular swimming areas it cannot cover every stretch of beach or body of water. Some of the most popular swimming, snorkeling, surfing, boarding, kayaking, wind-surfing, and diving spots are beyond sight of manned lifeguard posts, a few that are completely off the beaten path attract some because of its seclusion and the challenge it brings to the adventurous spirit of others. Add to this the growing number of water-related companies catering to tourists and locals alike, the chances of incidents and accidents ebb and flow with the tide of tourists who come to enjoy the warmth and Aloha of Hawaii. Clearly there is a need to augment and help the OS&LSD perform its duties to ensure water safety for the masses. This is where unmanned aerial systems (UAS) come in.

            There are many discussions about the numerous uses of UAS outside the military. Civilian practical applications of UAS are growing; perhaps one area where UAS will be of benefit is to augment lifeguards. UAS can patrol lengthy coastlines and beaches beyond sight of lifeguard towers; it can issue warnings before swimmers get into dangerous situations, or even drop flotation devices to those in distress. One such design is a Pars UAS made by RTS Ideas. The Pars drone underwent testing at the Caspian Sea in August 2013. It can deliver a number of life vests or flotation devices it carries as payload; can fly for 10 minutes at a speed of up to 7.5 meters per second and at a range of about 4.5 km. The Pars is light and inexpensive; it uses bright LEDs for illumination and to make it visible during night operations. Launch and recovery is possible from land or from a boat. RTS hopes to make its drone available in the near future (Pars Tests at Caspian Sea, 2013).

            Surf Life Saving Australia is testing various UAS to aid in patrolling its vast coastline and beaches. Partnering with an Australian company, V-TOL Aerospace, various platforms are in consideration to help patrol Australia’s 11,000 beaches (World's first ’Eye in the sky’ boosts beach safety, 2014). V-TOL Aerospace’s 1m wingspan “mini-Warrigal” and its 2.1m wingspan “Warrigal Explorer” can provide surveillance search and rescue support to lifesavers. The V-TOL “Arrow” is a 5m long heavy lift VTOL platform capable of carrying 100kg payload such as advanced sensors or rafts and other lifesavers. V-TOL also has quad rotor and octocopters in its lineup of UAS platforms, all sold as a system consisting of the aerial platform, cameras and software, ground station with its associated software systems and a launcher. When used together with manned search and rescue platforms these UAS systems provide extended lifeguard coverage capable of dropping life saving devices, detecting watercraft accidents, spotting predators, and notifying lifeguards to respond to emergencies (Unmanned Aircraft Systems: Aerial Robotic Devices, 2014).

            Using UAS to safeguard the public is not without challenges. Considerations for financing, training, regulatory requirements and restrictions, legal and ethical use must be addressed before UAS can take to the skies. Procurement, training, maintenance, lifecycle management, and operational costs can be a major factor in employing UAS for lifeguard purposes which usually rely on local government funding. Will the benefits of using UAS outweigh the cost when compared to hiring more lifeguards and building more lifeguard towers?

            Lifeguards, or operators of UAS in lifeguard duties, must also carefully consider which role UAS will play in the performance of their duties, whether it is patrolling or surveillance duties only or limited lifesaving duties such as dropping life vests, to search and rescue missions using bigger UAS platforms. Safety considerations are always a factor when operating any machinery around people. Lifeguards must ensure flight paths are as far away as possible from general public or structures to minimize damages or injury in case of failure. Privacy concerns will also surface, most likely from private personal dwellings close to observation areas than from beachgoers. The possibility of vulnerability to hacking is also a concern in both catastrophic failure and privacy encroachment scenarios. Along with proper training and operations, secure encrypted communications and system reliability are vital in UAS to prevent legal ramifications from impeding its widespread use in public safety and lifesaving duties around our Moana.

References

Ho, H., Speck, C., & Kumasaki, J. (2009, December). Visitor Injuries in Hawaii. Retrieved from PubMed.Gov: http://www.ncbi.nlm.nih.gov/pubmed/20034256

Pars Tests at Caspian Sea. (2013, October 13). Retrieved from RTS Ideas: http://rtsideas.com/index.php?option=com_k2&view=item&id=7:pars-test-at-caspian-sea&lang=en

Unmanned Aircraft Systems: Aerial Robotic Devices. (2014, April 30). Retrieved from V-TOL Aerospace: http://www.v-tol.com/page/unmanned-aircraft-systems/default.asp

World first ’Eye in the sky’ boosts beach safety. (2014, April 30). Retrieved from Surf Life Saving Australia: http://sls.com.au/content/world-first-%E2%80%99eye-sky%E2%80%99-boosts-beach-safety

Detect, Sense, and Avoid

     Air traffic control centers (ATCC) take responsibility for managing, takeoff and landing, and separation of manned aircraft operating within the national airspace (NAS) using ground-based radars at terminal radar control (TRACON) and air route traffic control centers (ARTCC). Along with voice communications with pilots Traffic Alert and Collision Avoidance Systems (TCAS) aboard most aircraft help maintain safe distances to avoid potential collision dangers. In the middle of all these technology sits the human factor, pilots and Air traffic controllers (ATC), using their senses and brain computing power to maintain safe operations in the air and on the ground. ATCs have an unenviable, highly stressful, job of ensuring the safe operation of over 90,000 planes flying across the U.S. everyday (over 5, 000 aircraft flying overhead at any given time), according to the National Air Traffic Controllers Association. In spite of the increasing density of air traffic pilots and ATCs manage to effectively perform their jobs to monitor aircraft and maintain separation.

      UAS operators, in essence, must play both parts to prevent collisions. As pilots of UAVs they must have situational awareness of their aircraft’s surroundings using flight cameras and instrumentation readings, all from the vantage point far removed from the aircraft itself. They must also perform as quasi ATCs in conjunction with other operators to maintain separation in segregated airspace. In non-segregated airspace, though, UAV operators must comply with local ATC instructions if they are to operate safely within the vicinity of commercial and general aviation (GA) aircraft. Communications between all involved must maintain a high degree of reliability and incorporate failsafe measures on the UAV. This is particularly important on the mid to upper size categories of UAVs where the potential for catastrophic collisions increases proportionally.

     Automatic Dependent Surveillance-Broadcast (ADS-B), currently in use and will be required on all commercial and GA aircraft by the year 2020, takes the sense and avoid capabilities of aircraft to the next level (Automatic Dependent Surveillance-Broadcast (ADS-B), 2014). Augmenting transponders, which can serve as backup, ADS-B can significantly enhance the UAVs’ ability to detect, sense and avoid other aircraft on the grid makes an argument for allowing safe integration into the NAS. Yet, this technology comes at a cost and may not be applicable to all UAV categories. The equipment necessary to utilize ADS-B adds weight and power demands on the UAV. While these requirements may be negligible on medium range to MALE/HALE UAV designs, they are of note when incorporating into smaller unmanned platforms where space, weight, and power are at a premium. The effect of the additional demands on the system comes into consideration compared to endurance or payload capacity.

      In looking towards integration of its UAS into the NAS, the US Air Force issued a request for information to technology vendors to build sense and avoid systems for its drones, called the Common-Airborne Sense and Avoid (C-ABSAA) Program (Cooney, 2014). The AF seeks alternatives to the Certificate of Authorization process and increase its mission options as military and commercial use of UASs expands. This, however, only addresses one issue of the many facing UAV integration into the NAS to include ensuring reliable command, control and communications, failsafe actions in loss-link situations, network security and anti-jamming or anti-spoofing capabilities, and interference issues in saturated RF spectrum. These are just a few issues that the UAS industry and aviation and government agencies face with the challenge of integration of UAVs into the NAS.

Reference

Automatic Dependent Surveillance-Broadcast (ADS-B). (2014, April 16). Retrieved from Federal Aviation Administration: http://www.faa.gov/nextgen/implementation/programs/adsb/

Cooney, M. (2014, April 17). Layer 8. Retrieved from Network World: http://www.networkworld.com/community/blog/air-force-wants-technology-will-let-drones-sense-and-avoid-other-aircraft

Heavy UAV

A UAS is to be designed for precision crop-dusting. In the middle of the design process, the system is found to be overweight.
• Two subsystems – 1) Guidance, Navigation & Control [flying correctly] and 2) Payload delivery [spraying correctly] have attempted to save costs by purchasing off-the-shelf hardware, rather than a custom design, resulting in both going over their originally allotted weight budgets. Each team has suggested that the OTHER team reduce weight to compensate.
• The UAS will not be able to carry sufficient weight to spread the specified (Marketing has already talked this up to customers) amount of fertilizer over the specified area without cutting into the fuel margin. The safety engineers are uncomfortable with the idea of changing the fuel margin at all

 

 

In a requirements based design process such as in the scenario described above it is vital to break down high level requirements, such as those promoted by the marketing department and management, into more design-specific lower level instructions and be able to communicate them clearly to subsystem design teams (Loewen, 2013). The design must meet prescribed requirements without sacrificing performance or safety, which in turn set lower level design parameters not met by the two subsystem teams. Weight is an important factor in aviation; it affects all aspects of aircraft design from propulsion, aerodynamics, structure, capacity and load, performance, and endurance, to name a few. The weight of all aircraft components, to include fuel and payload, goes into consideration when calculating center of gravity and ensuring the designed aircraft limits are not exceeded.

 

As the Systems Engineer (SE) in this scenario it is important to plainly communicate the requirements of the project to the entire group, that requirements based design does not tolerate slip ups (Loewen, 2013). While the use of commercial off-the-shelf (COTS) equipment saved some cost it did not succeed in meeting design limitations. Clearly, both teams in question will need to get back to the drawing board. Subsequent research and development (R&D) can move a step further by searching for even lighter alternatives to other components of the UAV. For example, materials used for airframe have evolved from the use of wood and canvas to aluminum to titanium to composite materials (Unmanned Aircraft Systems Roadmap, 2005). In essence, using lighter and stronger materials for aircraft structures as weight-saving alternatives is preferred in aircraft design. The teams can also search for innovative weight-cutting alternatives for other components of the UAV. However, the priority is to meet initial requirements first and get the final product out the door, while saving product enhancements for later versions. For example, using the fuselage or wing as the antenna can cut almost the entire weight of a traditional antenna system. Reducing weight even further will net improvements in payload capacity, performance, and operational costs which can make for desirable “nextgen” versions.

Reference

 

Loewen, H. (2013). Requirements-‐based UAVDesign Process Explained. MicroPilot, 1-17.

Unmanned Aircraft Systems Roadmap. (2005). Washington, DC: Office of the Secretary of Defense.