UAS in the NAS

Currently, the most common form of tracking airplanes from the ground is the utilization of radar; although radar has many limitations. Radar is ineffective when an aircraft is flying over large bodies of water or flying at low altitudes. However, manned aircrafts do utilize other forms of technology that offer pertinent data such as Global Positioning Systems (GPS) and transponders. While GPS is a great tool, airlines typically use it for navigation and do not transmit the information to air traffic controllers. Transponders can emit a radio signal containing information about an aircrafts speed, altitude, and identification. However, the information is only transmitted when requested upon. It is evident that improvements can be made in order to increase efficiency and accuracy within the National Airspace System (NAS).

The Federal Aviation Administration (FAA) has developed a proposal for a new and improved system named The Next Generation Air Transportation System (NextGen) to be implemented in stages between 2012 and 2025 (FAA, 2007). The concept is to convert the United States’ air traffic control system from a ground based system to a satellite based system. In order to accomplish this task, the introduction of Automatic Dependent Surveillance-Broadcast (ADS-B) to aircrafts will broadcast the aircraft’s position from satellite navigation over a radio frequency. There are many types of certified ADS-B data links, but two are the most popular 1090MHz and 978 MHz (FAA, n.d.). In order to alleviate congestion, the FAA has requested that all aircraft operating below 18,000 feet use the 978 MHz link (FAA, n.d.).

This technology can be implemented into the unmanned aircraft industry in order for manned aircraft to know the location, identification, and type of unmanned aerial vehicle (UAV) in their proximity. While the FAA will most likely set restrictions upon which UAV group can fly in specific airspace, along with sensor technologies onboard the UAV, the ability for manned and unmanned aircraft to relay data between one another is crucial to integrating UAVs into the NAS. Since UAVs have the ability to fly a fully autonomous flight plan, the data transmitted between the two aircraft using ADS-B will reduce the need for pilots to interrogate other aircraft transponders.

Certain considerations need to be made in regards to communication between pilots and UAV operators. UAV operators that are flying beyond line of sight are strictly relying on their sensor data to fly the UAV. If the data being relayed is inaccurate, the communication link between operator and pilot is essential to both parties safety. However, other technologies like Sense and Avoid are being researched in order to help assist in avoidance maneuvers/alerts; which will probably also be implemented into manned aircraft at a later time.

References 

FAA. (2007, February 14). Fact Sheet – NextGen. Retrieved April 20, 2014, from faa.gov:http://www.faa.gov/news/fact_sheets/news_story.cfm?newsid=8145 

FAA. (n.d.). Surveillance Broadcast.Retrieved April 20, 2014, from faa.gov:http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/surveillance_broadcast/general_information/

Weeding Out a Solution

In the development of a precision crop-dusting UAS, two subsystem teams (Guidance, Navigation & Control, along with Payload delivery) have decided to purchase off-the-shelf hardware in an attempt to save costs. In result, both teams have ended up going over their originally allotted weight budgets. Each team suggests that the other team reduce the weight to compensate. At this point, the UAS will not be able to carry sufficient weight to spread the specified amount of fertilizer without cutting into the fuel margin. The safety engineers are uncomfortable with the idea of changing the fuel margin at all.

In playing the role of a Systems Engineer, I would go about resolving this issue in a few different ways. First a Systems Engineer has to acquire all the current information about the dilemma in order to fully gauge the situation (Platt, 2011). I need to compare the customers’ requirements and the design/assembly capabilities of the company to where the current development of the UAS is at. The engineer will need to listen to both subsystem teams in order to hear all of their concerns (Platt, 2011). Communication is vital to fully understanding the two teams conflicting requests.

Once all of the information is gathered, potential solutions need to be addressed. It is important to annotate and research every possible solution that is brainstormed. Sometimes even an idea that seems like a waste will evolve into something that is worthwhile. A Systems Engineer needs to develop a list of priorities to tackle in order to create a set timeline as to not get off track (Platt, 2011).

In regards to this case, I believe there are multiple solutions that should be considered and researched further. The biggest issues with this dilemma are that neither team wants to compromise in their weight allowances and we’re not able to change the fuel margin. Since both teams have agreed to use off-the-shelf components, I would suggest that further research goes into what components are available.

One of the easiest ways to reduce the weight of a product is to build it with different (lighter) materials (Qantas, n.d.). Instead of a fiberglass or metal airframe, a carbon fiber construction may prove worthwhile.Even though the typical costs associated with more advanced materials are higher, the production costs could potentially be offset by a decrease in development costs. Additionally, I would research the engine/fuel components. A more efficient motor or propeller design may reduce weight and fuel consumption (Qantas, n.d.). Future generations may even have the capability to implement a hybrid type engine that utilizes a battery system during reduced throttle operation (Oliver, 2012). The weight of the batteries might offset the weight of the fuel needed and could potentially reduce operating costs at the same time.

Depending on how far along in the design/development phase the company is in, modifications to the airframe may be the future roadmap for the next generation of the UAS. Advanced aerodynamic engineering would contribute to less wind resistance, allowing the aircraft to cover more area. Also, an assisted launch mechanism could be implemented in order to reduce the fuel consumption of the aircraft trying to reach cruising speed from a standstill takeoff.

There are many potential solutions that an engineer will not be able to make an educated decision on which is best until they have reviewed all of the data pertaining to the solution in question. I think the most important thing is to prioritize the process by each step necessary and work each problem in collaboration with the whole design team. Just because these two systems are the ones in question, does not mean that modifications made to them will not affect other components of the UAS. Good communication between all parties is the best way to come to a compromise that will still produce acceptable results.

References 

Oliver, S. (2012, August 3). Take A Multifaceted Power Approach To Reduce Your UAV’s Weight.Retrieved April 6, 2014, from electronicdesign.com: http://electronicdesign.com/power/take-multifaceted-power-approach-reduce-your-uav-s-weight 

Platt, J. (2011, November). Career Focus: Systems Engineering.Retrieved April 6, 2014, from todaysengineer.org: http://www.todaysengineer.org/2011/nov/career-focus.asp 

Qantas. (n.d.). Fuel Efficiency at Qantas. Retrieved April 6, 2014, from qantas.com:http://www.qantas.com.au/travel/airlines/fuel/global/en