Multi-rotor aircraft, sometimes referred to as quadcopters because of the four propellers, require motors to give power to the propellers in order for them to turn at a rapid rate to create lift. All motors on a quadcopter are identical however, adjacent propellers spin inversely so that torques are balanced if all propellers are spinning at the same rate (Gibiansky, 2015). Pitch and roll rotation is controlled by increasing the speed of two motors on one side while slowing down the speed of the motors on the opposite side (Learn Robotix, 2015). All of these functions are controlled by the pilot from a Ground Control Station (GCS), most likely with a typical 100 milliwatt Flight Controller. RPAs pilots require their aircraft to be able to detect a minimum of 6-7 satellites to be able to double and triple-check its exact GPS coordinates and be flown legally.
Legal compliance is important and complying to the Civil Aviation Safety Authority's (CASA) air laws is mandatory. The following air laws apply to recreational RPAs and should be adhered to:
- You should only fly in visual line-of-sight, in day visual meteorological conditions (VMC)
- You must not fly closer than 30 metres to vehicles, boats, buildings or people
- You must not fly over populous areas such as beaches, heavily populated parks, or sports ovals while they are in use
- In controlled airspace, which covers most Australian cities, you must not fly higher than 120 metres (400 feet) above the ground
- You must not fly in a way that creates a hazard to other aircraft, so you should keep at least 5.5 km away from airfields, aerodromes and helicopter landing sites
- (Civil Aviation Safety Authority, 2009).
These laws are for safety reasons and should be followed in order to fly legally. With these laws in place, research and data can now be collected.
Research was gathered through an expedition to a pineapple farm in Beerburrum West state forest. The task was to see if it was possible for an unmodified DJI Phantom 3 Professional, shown in Picture-1, to map and survey a section of pineapple plants. Starting from a home point near the plants' location, the RPAs was launched up to a height of 50 metres (~164 feet) and was carefully piloted above the field in order for picture upon picture to be taken. Later, the pictures would be knitted together to form a whole picture which mapped the region of pineapple plants. Finally, the whole picture would be examined for its clarity and its viability as a mapping tool. Secondary research was also collected through reading news articles and aviation websites to look at how the consumer level RPAs market has boomed in recent years and how RPAs are becoming more affordable.
Research into the cost of consumer level RPAs shows how DJI and other manufacturers are making them more affordable and more accessible for inexperienced and amateur pilots to purchase. This means that having your own RPAs is now easier than ever before with companies such as DJI, Parrot and 3DR now selling them for less than $1,200. The exact figures for these companies are compared with the standard prices of professional level RPAs below in Table-1, Table-2 & Table-3: