## 2 UAS Platform Types and Characteristics
### Characteristics and Examples of UAS Categories
#### 2.2.2 Vtol UAS  
Most VTOL UAV history dates to the early 1960s (with a single exception of the creation of the Rolls-Royce Thrust Measuring Rig in the 1950s), and work progressed slowly through the 1970s and 1980s as technological limitations hampered the ability of engineers to realize the design goals for these vehicles. As these problems were overcome, major VTOL UAV developments occurred in the 1990s and through to the present. Figure 3 depicts dates of first flights or operational use of VTOL UAS, and their increased rate of development since the late 1990s (data for 2012 are estimates).  
The advantages of VTOL UAS are the portability of the platforms for remote area operations without the necessity for runway complexes. More of the current VTOL platforms are small, with most operating with electric motors from rechargeable batteries limiting flight durations to less than one hour. They have limited sensor payload capabilities but as miniaturization of sensors occurs, the platforms are proving more valuable for use in quick analysis situations. Examples of the utility of VTOL UAS platforms are to support law enforcement operations, where a low-altitude, hovering capability with image data capture is useful for ascertaining an incident scene. Scientific research applications requiring loitering capability over a fixed survey plot of relatively small size (e.g., agricultural field) are another area in which this category of UAV has significant potential. These platforms have also been demonstrated (in practice missions) in support of structure damage analysis and rescue operations in a complex urban structure environment (narrow streets, buildings, _etc._). With ease of maneuverability, VTOL can more readily negotiate an urban landscape at low altitude than can fixed-wing assets.  
For most VTOL UAS, Line-of-sight (LOS) operations are the common pilot control method. Most VTOL UAS operations for \"quick-look\" analysis (over the hill, around the building, _etc._) can be readily accomplished with a one- or two-person crew, making these platforms cost-effective for short-duration observational needs The Draganflyer X6 (Figure 4) is one example of such a system,  
Figure 3: Unmanned VTOL commercial platform systems developed (horizontal axis) by year between 1960–2012. Data for 2012 are estimates at the time of writing.  
with its 1 kg tri-rotor platform capable of lofting payloads of 500 g to altitudes of 2,400 m flights of up to 20 minute-flights. The Aeryon Scout (Figure 5), of similar size (80 cm \(\times\) 30 cm), carries a 300 g payload to heights of 330 m within an operational range of 3 km from its ground control station. Larger VTOL UAS systems are in development primarily to support military lift and transport operations (such as moving equipment in hostile, remote environments), but their wider application to supporting science and civilian utility has not been established yet.  
An example of a mid-sized, commercially used VTOL UAS is the Yamaha RMAX (Figure 6). The RMAX is a two cycle/two cylinder UAS helicopter with a 28 kg load capacity, 3.13 m main rotor diameter platform with remote control systems via a line-of-sight ground control station. It has been  
Figure 4: Draganflyer X6 VTOL UAS. Image courtesy Draganfly Innovations, Inc.  
Figure 5: Aeryon Scout VTOL UAS. Image courtesy Aeryon Labs, Inc.  
employed primarily for agricultural spraying operations in Japan, Australia and other locations. RMAX has the payload capacity and endurance to support remote sensing system operations, and has flown with various experimental remote sensing systems at NASA-Ames Research Center in a collaborative effort with the US Army under the NASA/Army Autonomous Rotorcraft Project (ARP) [8].