The war in Ukraine has shown how drones can be used effectively in combat but there are a range of different designs, with each bringing their own military capability.
Depending on the operation – what the target is, how much distance needs to be covered and the geographical location among other considerations, each drone can serve its own purpose.
Factors such as time in the air, distance, weight, and the speed the drone can travel all play a part in using a particular drone to reach a particular target.
Here, Forces News takes a look at how aerodynamics dictates how each drone, or unmanned aerial vehicle (UAV), is used in combat with expert analysis on some of the designs that have been used in the war against Russia in Ukraine.
The Iranian Shahed is often referred to as a drone or suicide drone, but in official technical terms, it is a loitering munition.
Primarily used for strike action, the craft’s design allows it to remain in the air for longer which enables it to find its targets more effectively.
Professor Peter Lee, a former Chaplain in the RAF and now Director of Security and Risk Research and Innovation at the University of Portsmouth, whose research covers drone operations in the military and the ethics of autonomous weapon systems, said: "The delta design (Shahed) gives you a very large surface area. The more surface area you have on your drone or aircraft on the wings or just the body, the more lift you get.
"The more lift you have the easier it is to stay in the air with slower forward motions.”
This allows the aircraft to stay in the air a longer time with same power output, or carry more weight.
The Beaver’s design uses the shape of its angled wings to provide the operator with more control.
Another drone primarily used to carry out strikes, the Beaver can move at a significant speed and therefore would be harder for defenders to intercept or shoot down.
Professor Lee said: "If you have a design with angled fins, you want to be able to control your pitch; on going up and down, your roll and your yaw. Your yaw is the side-to-side movement.
"It can give you some greater efficiency whilst still having the ability to control the aircraft in the direction you want it to."
Using angled-up wings, the Bayraktar has the ability to take off and land from a runway. It also has a variety of uses including surveillance, intelligence gathering and strikes.
"With the Bayraktar its tailfins are angled up of the blade in front of it, and that is the configuration for a number of reasons. One of which is simple take-off and landing", said Professor Lee.
"The Bayraktar design means it can rotate better and take off and land at different speeds without risking damaging the tail section."
Another craft used to strike; the Lancet is described by Professor Lee as "a missile" with control systems to guide it, rather than a conventional drone.
Often used by the Russian military in Ukraine, the Lancet benefits from speed and can be made at a low cost.
"It gives you enough accuracy to have the effect you want, but at a much cheaper cost.
"You are trading cost for efficiency and effectiveness but in some of the attacks Russia is making in Ukraine, the main object isn't always to destroy everything in sight.
"You may just want some explosive destructiveness. The Lancet has accuracy and control ability."
VTOL (Vertical Take Off and Landing)
Crafts designed for vertical take-off and landing (VTOL) benefit from horizontal motors, however, this can make them heavier.
Using down-facing engines the drone can be lifted into the air, and this is supported by horizontal motors underneath. These drones can also be used for surveillance, intelligence gathering and strikes.
Professor Lee said: "The United States Navy often used aircraft with their rotators facing upward to lift the aircraft.
"As a drone, technically it would be possible to do but you then make the drone heavier because you have to have mechanisms to take your downward facing motors and turn them in a horizontal direction in order to get forward thrust."
Due to its size, the Quadcopter is limited to reconnaissance, small strike actions or payload deliveries.
Professor Lee said: "The Quadcopter has a degree of redundancy, and it allows good stability with all four motors.
"Whether it's a very tiny quadcopter, something off the shelves, or much bigger that can carry tens of kilograms.
"The challenge is always how do you power it? Motorized engine with fuel supply or do you go for battery?"
Unconventional drones can also be used in warfare and can carry out various roles.
Despite not being advanced, their cheap price and the ability to replace them quickly means they can provide accurate reconnaissance on the battlefield.
Professor Lee said: "If you have two or three (OTS drones) you can cycle up the 30 minutes, bring it back and replace it with another for 30 minutes, swap the batteries over, and you can keep a good system of observation for one or two days.
"Essentially, you’re using those to do what biplanes did in the First World War. They would take off, look above the trenches, and try to spot enemy positions, artillery, and troop movements."