MEMORANDUM

TO:                  Guidance and Payload teams

FROM:            Greg Laxton

  Chief Systems Engineer

DATE:              August 20^th, 2015

SUBJECT:       EXCESS WEIGHT ON THE “WEED WETTER”

 

Our team appears to be at an impasse regarding excess weight of the “Weed Wetter”. To be successful, we must meet three objectives; be on time, be on budget and meet customer expectations. Its success is tied to our success. Currently we are 10% over weight. This takes us away from the derived requirement (Terwilliger, Burgess, & Hernandez, 2013) of two acres per hour from each Wetter. It is imperative we have a 5% improvement from both teams

To the payload team; please include the safety engineer in your discussions. There must be an area of compromise where you can find a solution with less fuel and less fertilizer. The current refuel and reload time is expected to be four minutes; if you can find efficiency in the turnaround process, perhaps you can treat the promised acreage. More flights of shorter duration may meet the target spray with the current vehicle design. Could we find room for improvement by relocating the supply vehicle closer or changing the spray pattern?

To the guidance, navigation and control team; please bring propulsion in to your discussions. Are there improved power plants that would provide more lift with the same weight? It has been a year since you finalized the engine choice, please check with NWUAV ("NWUAV EFI Multi-Fuel Engine," n.d.) again and inquire how soon the NW-45 will be available. All team members should investigate similar commercial off the shelf improvements that would help meet your target.

Traceability (Lowen, 2013) for all teams is critical. Please track any changes using the existing metric and plan to submit your improvements during the formal program review (Terwilliger, Burgess, & Hernandez, 2013) meeting next week.

We’re at a critical phase in development team, and I’ve authorized 10% overtime until Friday, the 28^th of August.

 Lowen, H. (2013). Requirement-based UAV design. Retrieved from http://www.micropilot.com/pdf/requirements-based-uav.pdf

NWUAV EFI Multi-Fuel (Heavy-Fuel/Gas) Engine. (n.d.). Retrieved from    
           http://www.nwuav.com/uav-products/heavy-fuel-engines.html

Terwilliger, B., Burgess, S., & Hernandez. (2013, September 25). MODULE #2 GLOBAL
           SYSTEM DESIGN CONCEPTS, REQUIREMENTS, AND SPECIFICATIONS
           OVERVIEW [PowerPoint].

Lightning Bug to Global Hawk

Gregory D Laxton

Embry-Riddle Aeronautical University, Worldwide Campus

ASCI 530

Assignment 1.4

 

 Lightning Bug to Global Hawk

The Ryan Aeronautical Company of San Diego, California, provides an excellent series of examples for comparison and evolution of early unmanned reconnaissance aircraft. The Global Hawk high altitude long endurance (HALE) unmanned aerospace system (UAS) can trace its heritage to early Ryan Aeronautical model 147 drones (Katz, n.d.). In the early 1960s, manned intelligence gathering flights over China and Russia became more perilous for US crews, most notably after the 1962 shoot down of the American U-2 spy plane over the Soviet Union and capture of pilot Gary Powers (History.com-Staff, 2009). Unmanned platforms for intelligence, surveillance and reconnaissance (ISR) missions provided a logical solution. Ryan Aeronautical was contracted and produced the model 147 and later variants, which were used by the military for decades in a variety of roles (Blom, 2010).

            Ryan was acquired by Teledyne in 1968 and Northrop Grumman in 1998 ("Our Heritage," n.d.). There have been significant technological improvements to UAS since the Ryan Model 147B Lightning Bug was delivered to the Air Force in 1964 (Blom, 2010, p.57), but the heritage from the manufacturer is evident. For example, both systems are HALE platforms with high aspect ratio wings, used for intelligence gathering without risk to aircrew. The Teledyne Ryan YQM- 98A Compass Cope, depicted in figure 1, first flew in 1974 (Blom, 2010, p.66) and like the Global Hawk, features a top mounted single jet engine, high aspect ratio long mid body wing, and twin vertical stabilizers (Katz, n.d.).

 

Figure 1 Teledyne Ryan YQM-98A. From Katz, Before Predator: The Early History of Remotely Piloted Aircraft. Retrieved from http://www.sfte2013.com/files/75234565.pdf

In 1974 the YQM-98A Compass Cope flew for over 28 hours (Blom, 2010, p.56). An endurance record that lasted 26 years until the Global Hawk flew a 31.5 hour mission from Edwards Air Force Base, California ("Global Hawk breaks record," 2000).

            Size and capability separate the modern RQ-4 Global Hawk, depicted in figure 2, from its predecessors.

Figure 2. Northrop Grumman RQ-4 Global Hawk. From Katz, Before Predator: The Early History of Remotely Piloted Aircraft. Retrieved from http://www.sfte2013.com/files/75234565.pdf

The RQ-4 has a 139 foot wingspan and maximum takeoff weight over 32,000 pounds ("Global Hawk," n.d.). Alternatively, the Ryan model 147B featured a smaller wingspan of only 27 feet (Blom, 2010, p.56). Capabilities have dramatically improved, as would be expected. The RQ-4 has long loiter times and large payloads of sensors. In this respect, the mission of the new platform aircraft is very similar to the original; remote observation in hostile airspace and convey information back to decision makers, without putting a pilot in harm’s way. An advantage of using unmanned systems during heightened political tensions is denying an adversary the propaganda tool of captured aircrew. Modern platforms like the RQ-4 bring networked real time sensor information with the added benefit of streaming video to the battlefield commanders.

            New technology will invariably change the capabilities of HALE platforms. A promising idea is solar powered aircraft that can loiter for days or months, rather than hours. Current examples of large solar powered UAS include the Facebook Aquila, Google’s Titan project and the cancelled Boeing Solar Eagle (Warwick, 2015).  A vehicle of this type paired with the sensor and communication packages of the RQ-4 would be a formidable asset.

 

References

Austin, R. (2010). Unmanned aircraft systems: UAVs design, development and deployment. Chichester, UK: Wiley

Blom, J. D. (2010). Unmanned aerial systems: A historical perspective. Fort Leavenworth, KS: Combat Studies Institute Press.

Global Hawk. (n.d.). Retrieved from http://www.northropgrumman.com/Capabilities/GlobalHawk/Pages/default.aspx

Global Hawk breaks record. (2000, May 2). Retrieved from http://www.flightglobal.com/news/articles/global-hawk-breaks-record-65081/

History.com-Staff. (2009). U-2 Spy Incident. Retrieved from http://www.history.com/topics/cold-war/u2-spy-incident

Katz, K. P. (n.d.). Before Predator. Retrieved from http://www.sfte2013.com/files/75234565.pdf

Our Heritage. (n.d.). Retrieved from http://www.northropgrumman.com/AboutUs/OurHeritage/Pages/default.aspx

Warwick, G. (2015, March 30). Facebook’s UAV. Retrieved from http://aviationweek.com/technology/facebook-s-uav-flies-builds-developments-solar-power