UAS Classifications

Although UAS can be described by their configuration of the UA (e.g. fixed wing, co-axial rotorcraft) these are not always useful, especially when comparing two or more UAS’s suitability for a particular mission, as the configuration tends to be driven by the requirements[15]. This may result in two aircraft with dissimilar configurations being suited for the same role (e.g. crop spraying could be carried out by either a fixed wing UA or rotorcraft UA), therefore it is best to use the type of configuration as a detail of the UAS rather than a defining character.

There are currently several different ways in classifying UAS into groups, depending on the preference of the body grouping them. Some of these different ways are described below. These classifications are not necessarily mutually exclusive, as a UAS can be accurately described by a combination of them (i.e. the role the UAS is to perform and the range it is to perform it at). 2.1.7.1 Mass

Dividing UAS into different mass bands (based on the mass of the UA, not the whole UAS) is probably the simplest way of grouping UAS. This method is currently in use with the CAA, which splits UAS into the weight categories (i.e. mass in the context present of the earth’s gravitational field) for the purpose of regulation and the MoD, which splits them into three classes. Figure 2-4 shows the MoD UAS weigh classes (and categories) and their CAA equivalent. One problem that may arise from this classification is that the weight categories may be subject to change, for whatever reason (e.g. change in the regulations for UAS), and the resulting reshuffling of UASs into different bands may cause confusion.

Figure 2-4 MoD UAS Classes [36] 2.1.7.2 Roles

A useful way of presenting how UASs are currently being used (and possible future uses) is in what roles they will carry out, rather than stating particular mission types (e.g. surveillance, crop spraying). Presenting UAS applications in this way allows the advantages to be seen in non-mission specific terms.

Traditionally UASs have only sought to take on DDD (Dull, Dirty, or Dangerous) jobs[15; 40; 41], because they are mainly military roles and benefit from removing humans from the aircraft, but there are other roles in which UAS are well suited[15], some of these roles are listed below. It must be noted that a UAS may cover more than one of these roles for any given mission (e.g. a surveillance mission is considered to be dull, but also in many cases has the need of being covert). Currently the majority of UASs used are military, and the civilian market (globally) is predicted to emerge in this decade, initially in roles/missions similar to military ones (e.g. surveillance by a boarder control agency)[41].

 Dull Roles – Jobs deemed tedious or boring, e.g. surveillance, crop monitoring. These jobs tend to last over 24 hours[15; 41] (the main dull job currently being military surveillance), and using a UAS allows for one

crew to relief another without the UAS needing to land for this to happen[15].

 Dirty Roles – Jobs with environmental factors which could endanger the health of humans, e.g. NBC (nuclear, biological, and chemical) monitoring, crop spraying.

 Dangerous Roles – Jobs where there is danger of being shot at, primarily military roles, but also possibly some law enforcement ones as well.

 Covert Roles.

 Research Roles.

 Environmental Roles.

 Economic Roles – Could be based initial costs, operating costs, or life- cycle costs. Also, lack of labour force could – as with Japanese agricultural industry, where due to dwindling rural populations, helicopter like UAs have been used for crop spraying since the 1960s[2; 15; 42] 2.1.7.3 Range & Endurance

Classifying UAS by range and endurance is quite a useful method, as the weight of a UA will limit the amount of fuel on-board, and the amount of fuel will affect range and endurance of the UA, this method of classifying can be linked to weigh base method (and thus to what regulations are to be used) as is the case in Figure 2-4. There are three main groups for this method, they are as follows:

 Long Endurance, Long Range – Designed to generally fly beyond line-of- sight (BLOS) (but may not always be the case) for prolonged periods of time (over 24 hours[15]). This group is generally broken down into two sub-groups based on the operating altitude, they are:

o High Altitude Long Endurance (HALE) UAS operate over 15,000 m altitudes and their operations can be global in scale[15]. They a r e s u i t e d t o r e c o n n a i s s a n c e a n d s u r v e i l l a n c e r o l e s . o Medium Altitude Long Endurance (MALE) UAS operate between 5000 – 15,000 m[15] and their operational range is over 500 km but less than HALE UASs[15]. They too are suited to surveillance and reconnaissance roles, but the lower altitude at which they operate allows other roles such as the case with Predator being

 Medium Range & Tactical – Medium Range or Tactical UAS generally operate in the range of 100 – 300 km[15]. Their endurance vary somewhat, but tend to be under 24 hours.

 Close Range & Battlefield – These UASs tend to be designed to be used in visual line-of-sight (LOS) for ranges up to 100 km[15]. This group has the widest set of operational areas (e.g. surveillance, crop spraying, NBC monitoring) and their endurances also vary and can last from a few minutes to hours. There are three sub-groups (although not all UASs in this group will fit into the sub-groups), they are:

o Mini Unmanned Aerial Vehicle (MUAV, MiniUAV) have a mass of less than 20 kg, have range up to ~30 km, and may or may not be hand launched.[15]

o Micro Aerial Vehicle (MAV) or MicroUAV tend to have wing span of around 150 mm or less and are intended for use in urban environments[15].

o Nano Aerial Vehicle (NAV) are about the size of insects or seeds[15].