Task Specific UAS Design

As the popularity of unmanned aerial systems grows many different groups have tailored designs to fit their particular need. Unmanned systems have been proposed to do everything from providing worldwide cell and wifi service, to replacing your mailman. However, the times when UAS shine the brightest is when they can perform a task that prevents a human from risking life and limb. Many unmanned systems have been designed or modified to  assist firefighters by detecting and tracking fires and also by delivering water directly onto the blaze.

Just this month a joint team from Lockheed Martin partnered with Kuman unmanned aircraft gave a demonstration of a K-MAX helicopter with an upgraded sensor package that was able to autonomously detect fires and deliver up to 680 gallons of water per trip (Gabbert, 2014). Originally a manned helicopter, the K-MAX was converted to a UAS by Lockheed back in 2007. The K-Max has a  high payload to weight ratio and this made it an ideal choice for a water delivery system (K-MAX, 2014).

Back in 2007 the United States Forest Service bought 2 SkySeer UAS to help monitor wildfires. The SkySeer is much better at tracking fires because it’s infrared cameras are not hindered by the smoke. Unfortunately, due to current FAA regulations the Forest Service is not allowed to operate UAS (Gabbert, 2013). The SkySeer is small, lightweight, and with a price tag around $30,000, much less expensive than other options (Bowes, 2006).

The lifting capacity of the K-MAX and the low cost of the SkySeer make them well suited for assisting firefighters, especially when it comes to battling forest fires.

References:

Bowes, P. (2006, June 6). Retrieved November 29, 2014, from http://news.bbc.co.uk/2/hi/americas/5051142.stm

Gabbert, W. (2014, November 18). Fire Aviation. Retrieved November 29, 2014, from http://fireaviation.com/tag/uav/

Gabbert, W. (2013, December 4). Fire Aviation. Retrieved November 29, 2014, from http://fireaviation.com/2013/12/04/forest-service-not-using-100000-drones/

K-MAX. (2014, July 1). Retrieved November 29, 2014, from http://www.lockheedmartin.com/us/products/kmax.html

UAV integration into the NAS

Deconfliction of small and medium scale UAVs comes down to data-link capability. Loading such an aircraft down with all the sensors required to detect and avoid other aircraft is simply not cost effective. However, given a reliable data link, each aircraft can report it’s own position to a central ATC facility and receive warnings about potential hazards at the same time. However, even sending these updates once a second can be a huge amount of data with enough aircraft in the sky. The DoD estimates the needed data throughput at 20 Gbps for a fleet of some 700 drones. While this data rate itself is not insurmountable, when you consider that it must be reliable and available over a large geographic area, the situation becomes more complicated. While this estimate includes the video and control feeds, it does give an idea of the order of magnitude of bandwidth needed. By that I mean that a military drone has a much higher need for an HD video feed for target designation and surveillance reasons than a standard civilian cargo UAV would need (Milsat, 2012).

Once the use of data links helps UAVs avoid each other, then each individual aircraft can worry about avoiding other obstacles, such as birds. The difficulty of this task decreases rapidly with increasing altitude. Also, most of these obstacles move relatively slow when compared to aircraft, providing a slightly longer timescale to detect and avoid them.

References:

Furstenberg, D. (2012, March 1). Intel: Meeting The Growing Bandwidth Demands Of A Modern Military. Retrieved November 13, 2014, from http://www.milsatmagazine.com/story.php?number=855426811

Systems Engineering - Conflict Resolution

In the event that a systems engineer must act as an intermediary between two groups that have gone outside their design specifications in order to reduced cost there are many different things that must be considered
In this example the Navigation & Control team  and the Payload delivery team have both gone over their weight allowance in order to use COTS hardware in an attempt to reduce cost and production time. In order to get the project back on track the systems engineer needs to consider several different aspects of the problem:

How much to both systems weigh, and by what percentage did they go over the allotted weight limit?
How close is the production deadline and how much time and money will it likely cost in order to design custom systems for both approaches?
How much of a benefit is COTS hardware?

The first question is important because the system that weighs more will probably have an easier time reducing its weight. For example, if the amount that the Payload team went over was more than the entire weight of the navigation system, then there is no point asking the Nav team to try and make up the slack.
The second aspect is time. If production is far enough out, both teams can be expected to give plans for alternate, lower weight (although higher cost) systems. Obviously this is not always an option, but having both teams attack the problem will often yield better results than insisting that any 1 team fix the problem alone.
The third question is about determining how much of a benefit you are getting out of COTS hardware in the first place. There are many possible benefits including reduced cost, availability of parts, and warranties. All of these things must be weighed against the cost of redesigning large systems of the UAS in order to meet the weight requirements.

During the process of attempting to validate the weight requirements it is important to keep the customer in the loop. They need to know up front about the potential cost overrun that will come with keeping to the original design specifications. At that point, they can make the decision if they would rather have reduced capability or increased cost (Loewen, 2013).

References:
Loewen, H. (2013). Requirements-Based UAV Design Process Explained. MicroPilot.