Drones

Credits

Introduction

Not very many years ago, few people had even heard of drones. Most of those who had would probably have an idea from science fiction or techno-thrillers about what a drone was and what it might be capable of, but no real knowledge. Yet, in just a few years, drones have gone from obscurity to near-constant media attention. We hear of drone strikes and drone surveillance in the world’s trouble zones, and of drones delivering packages – even pizza – in the commercial world.

Asurprising number and range of users have been operating drones for some time, although the rest of the world has known little about it. Outside of the military, drones have been used for research purposes, or to monitor the environment. Commercially available drones can now be bought at quite a cheap price by private users for recreational purposes.

Yet, in truth, there is nothing really new about the idea of a remotely operated vehicle. The word ‘drone’ has entered the popular vocabulary, but long before this happened users were flying remote-controlled aircraft and helicopters, or racing radio-controlled cars. Remotely controlled weapons have been in use for several years – although not always with a great deal of success. It is, however, debatable whether these were, strictly speaking, drones.

What is a Drone?

One useful definition of a drone is a pilotless aircraft that can operate autonomously, i.e. one that does not require constant user control. This means that traditional radio-controlled aircraft and the like are not, in the strictest sense, drones. Nor are many underwater Remotely Operated Vehicles (ROVs), and not only because they are not aircraft. In fact, many recreational ‘drones’ are not really drones, as they are semi-autonomous. However, it is useful to widen the definition of a drone somewhat in order to cover a range of similar vehicles that undertake the same role using broadly the same principles.

RQ-4 GLOBAL HAWK

SPECIFICATIONS: RQ-4 GLOBAL HAWK

Length: 14.5m (47ft 6in)

Wingspan: 39.8m (130ft 6in)

Height: 4.7m (15ft 4in)

Powerplant: Rolls-Royce North American F137-RR-100 turbofan engine

Maximum takeoff weight: 14,628kg (32,250lb)

Maximum speed: 574km/h (357mph)

Range: 22,632km (14,063 miles)

Ceiling: 18,288m (60,000ft)

Endurance: More than 34 hours

Operating a UAV is a complex business, which has been described as similar to flying a plane whilst looking through a straw. In addition to piloting the vehicle, operators must control cameras, radar and other instruments, and hand-off data to other users, making the operation of a large military UAV a multi-person task.

It is quite difficult to pin down a working definition of ‘drone’ that does not immediately founder on the rocks of the first exception it encounters. In theory, any remote-controlled aircraft can operate like a drone, inasmuch as it can be pointed in the right direction and set to fly straight and level. During this period, the operator can let go of the controls and the aircraft will go on its way without control input.

This is not really a drone operation, however. To be such, the aircraft would need to be able to make some decisions for itself. A simple autopilot that used the aircraft’s control surfaces to keep it on course might not qualify, but one that could be given a destination and fly the aircraft to it, possibly making course changes as necessary, would fit the common definition of a drone.

Some ‘drones’, especially those operated by the military, are primarily operated by a pilot from a ground station. They can undertake autonomous flight, but are normally under constant control. Military drones, such as Predator, require considerable piloting skills and push the boundaries of what is, and what is not, a drone. Indeed, many operators dislike the use of the term ‘drone’, as what they do is every bit as difficult as flying an aircraft that they are aboard.

HOW DRONES WORK

The majority of small UAVs resemble the miniature aeroplanes flown by radio-control enthusiasts for many years. There are more design options as size increases. The RQ-2 Pioneer at centre rear is essentially a conventional small aircraft whilst the RQ-15 Neptune at right rear is a flying boat designed to land on water.

AUTONOMOUS LANDING PROCEDURE

A US military Predator drone, flying under constant control by a ground operator, is not really a drone under the strict definition above. It is an Unmanned Air Vehicle (UAV), a term that its operators prefer in any case. Similarly, a remotely operated vehicle used for underwater operations – say inspecting deep-water pipelines – may be under constant control and would best be considered a Remotely Operated Vehicle (ROV) or an Unmanned Underwater Vehicle (UUV).

Missiles and torpedoes meet the definition of a drone in many ways. They can guide themselves, making decisions about flight path or direction of travel, and often operate autonomously. Some are manually guided or home in on a manually controlled targeting system, such as a laser designator. Missiles and torpedoes are not, however, normally considered to be drones, even though there are drones that fulfil a similar role.

Likewise, it can be difficult to decide whether a given vehicle is a drone or not by just seeing it in operation. A drone-like aircraft could be under constant manual control, perhaps by using a First-Person View (FPV) system. This is essentially a camera in the front of the vehicle that gives the operator a pilot’s view. A small aircraft-type ‘drone’ might be a traditional model aircraft, or might be flying under its own control using GPS guidance.

Thus the field of drone operations is rather complex and overlaps in some other areas. For our purposes it must suffice to use a fairly loose definition of the term ‘drone’. We shall therefore consider a drone to be any vehicle that has no pilot aboard, and which is capable of at least some autonomous functions that require onboard decision-making, and which does not obviously fall into some other category, such as a missile or a guided artillery shell.

Historical Attempts

Historically, there have been numerous attempts to create pilotless vehicles, mainly for military purposes. Among the more ludicrous was the idea of using ‘organic control’ in a missile. The organic control took the form of a pigeon trained to recognize a particular type of target and peck at it. The intrepid pigeon could then guide a missile to the target by pecking at a screen in the front of the missile, which was connected to the controls to allow corrections. With the missile centred on the target, the pigeon’s pecks would keep the missile on course; deviation would be corrected as the pecks moved further from the centre of the screen.

The development of electronic systems small enough to fit inside a missile ensured that organic control was abandoned in the early 1950s. It has not, strangely enough, been revisited.

Other attempts at creating autonomous vehicles, also originating in World War II, were more straightforward. The V1 ‘flying bomb’ was essentially a pilotless aircraft powered by a pulse-jet engine. It was of simple construction and cheap to build, but carried a significant warhead. The V1 had an autopilot of sorts, which kept it level, and a very simple inertial system that activated the dive mechanism. A small propeller on the front of the V1 was driven round by air passing over the nose. When the propeller reached a preset number of revolutions, the bomb would, in theory, have travelled the requisite distance and should begin its dive towards the target.

V1 FLIGHT PATH

In practice, the careful calculations used to determine the dive point were thrown out by headwinds, tailwinds or imprecision in the device, causing many V1s to fall long or short. A side wind would also send the device off course. It had no navigation system as such, merely being launched in the direction of the target. This also made the V1 vulnerable to interception by aircraft and ground-based guns, as it had to follow a straight course.

Lack of a true autopilot allowed the flying bomb to be defeated by either flying ahead of it so that the slipstream of an aircraft caused it to veer off course and crash, or by the rather more hands-on approach of tipping the wing while flying alongside. The warhead did still come down somewhere, but it could be sent off target and prevented from striking a densely populated area.

The Mistel

The V1 flying bomb was not a drone as such, nor was it a missile. It can be considered a precursor to the modern military drone and missile, and helped prove the concept was workable. Another attempt at the same goal was the German ‘Beethoven Device’, a composite aircraft created from a single-seat fighter riding atop a larger aircraft. The latter, known as the ‘Mistel’, was packed with explosives and flown by remote control from the smaller aircraft.

The Mistel was usually a light bomber, such as a Ju-88, although various aircraft were used. Often these were obsolete designs, the intent being to obtain some useful service from aircraft that otherwise would have to be retired. In theory, the composite aircraft was flown close to the target, after which the fighter would escape while the Mistel component delivered its large warhead to the target. In practice, although over 200 of these devices were built, few achieved any useful results.

The final development of the Mistel concept was to have used jet aircraft that were emerging at the end of the war. This was a rather wasteful deployment of advanced combat aircraft, especially since the Mistel could deliver a relatively limited warload, and could, of course, do so only once. The composite aircraft was also very vulnerable to interception.

The V1 was a rather primitive forerunner of the modern cruise missile. Its effectiveness was limited by the lack of a remote piloting capability or an effective automatic navigation system. The technology to implement these systems had not yet been invented, which was fortunate for the intended victims.

Although not a drone in the true sense, the Beethoven Device was a credible attempt – given the technology of the day – to create something in between a guided missile and a one-use attack drone aircraft. It was ultimately a failure, but demonstrated the concept of a pilotless aircraft capable of – in theory at least – undertaking a combat mission.

Other wartime projects included radio-controlled glide bombs and acoustic homing torpedoes, which had at least some of the characteristics of a drone weapon. Although these were of limited impact during World War II, they did work, and well enough that the technologies were further explored. This led to the development of modern torpedoes and guided missiles of various sorts, whose technology would pave the way for drones. Without the work done on missile guidance just after World War II, today’s drones would not be possible.

The Mistel concept was an attempt to create a guided weapon using manual control. The pilot detached his small aircraft from the larger, explosives-packed carrier and guided its final approach to the target by remote control. Attacks were made by this method, though with limited success.

By the mid-1950s, radio control of model aircraft was common enough that contests like this one could be held. The development of remote control filled in one of the missing elements that led from crude pilotless flying bombs to modern UAVs.

The idea of a remotely piloted vehicle continued to be developed after the war, not always by the military. Radio guidance systems used in glide bombs and primitive missiles were eventually developed to the point where civilian enthusiasts could fly model aircraft and helicopters for recreation. The affordable radio-control hobby expanded to include boats and racing cars, and today it is sufficiently cheap that radio-controlled children’s toys are commonplace.

None of these developments created a drone, as such, but they were all steps towards that goal. Ever more powerful miniaturized electronics made it possible for a model aircraft to carry a fairly powerful processor – one that could handle decision-making if need be. This made it possible for a true drone to be created; one that could be instructed with what to do – for example, the start and end points of its flight path and a few waypoints in between – and left to make its own decisions about exactly how to carry out these instructions.

Advances in materials technology were important to the creation of workable drones, as well as to the aircraft industry in general. Lightness and strength are crucial when building any air vehicle; weight saved from structure can be used for payload. This is particularly important with small drones, where just a few grams can make the difference between being able to carry a useful payload and not getting off the ground at all.

A greater choice of materials is possible with smaller drones that do not have to carry humans, cargo and the heavy engines required to provide enough thrust to get off the ground. It would simply not be possible to build a full-sized aircraft out of some of the materials used to produce drones. The stresses experienced by a small drone during flight or landing are totally different from those encountered by larger aircraft, but as size increases, a drone must be constructed more like a conventional aircraft.

Missile guidance drove the development of many systems now used in UAVs. The AIM-9 Sidewinder missile first saw action in 1958, but did not always meet expectations. This test in 1974 at Point Mugu was part of ongoing development that resulted in the AIM-9H model, the first with solid state electronics.

The introduction of the Global Positioning System (GPS) was another critical technology. GPS signals are available to any device that is capable of receiving them, making it unnecessary to carry more than a receiver. This made accurate navigation possible without needing to carry numerous instruments or requiring operator updates, and this was a key factor in enabling modern drones to operate autonomously.

Communications technology also had to advance to the point where systems developed for other purposes could be co-opted for drone operations. Developing a control system purely for the purpose of recreational drone flying would make it a hobby for the very rich only, but today’s communications equipment has gone beyond single- purpose items. Indeed, interoperability and compatibility are strong selling points for tablets, laptop computers, mobile phones and the like.

EBEE

The Ebee drone was designed to enable users to produce maps using aerial photography. It is launched by hand, simply by throwing it.

The availability of general-purpose, programmable communications and computer equipment meant that drone manufacturers could make use of existing technology. For those on a military budget, this was less critical than in the recreational sector, but, all the same, use of Commercial Off-The-Shelf (COTS) components drove down both development costs and the price tag of the final unit. For the recreational and private civilian user, this was the development that made drone operations possible at all.

Thus it can be seen that today’s drones – military, commercial, recreational and all other types – were not created out of nothing. They are the end product of a process that began with crude experiments and expedients using whatever technology was available, and later developed into sophisticated systems once the requisite technology became available. Much of this was not specifically created for drone operations, but it was adopted or adapted from other applications.

Now that drone technology has become a mature field, it is likely that development of future systems will be – in some cases at least – specific to the field. This was not possible until it had been proven that there was money to be made from developing new and better drone technology; this is definitely now the case.

Drones are becoming increasingly common in a variety of applications, which is raising some new questions. Is it ethical to mount weapons on an unmanned aircraft? Or to permit anyone to fly a camera-carrying drone more or less wherever they please? What are the implications for national security? For privacy? Are drone-captured images acceptable as evidence in court? What laws need to be enacted to regulate the operation of potentially dangerous flying machines in urban areas?

As with any new technology, society needs time to adjust. Law and social custom must adapt to what is being done rather than attempting to guess what might happen based upon what is possible or foreseeable at the time. It is not always possible to predict the uses to which an emerging technology might be put, and of course, not all technologies live up to expectations.

What is clear at the present time is that drones have opened up new possibilities in some cases, and in others have made capabilities accessible to private users on a tight budget. It is now possible to spray crops more cheaply with a drone than by hiring a pilot and a crop-duster aircraft.

A farmer or conservationist can fly a model aircraft over an area and receive up-to-the-minute images of vegetation or wildlife. Law enforcement agencies can put a camera in the air for a fraction of the cost of a helicopter, and the military can undertake long-range surveillance of an area without the cost and potential consequences of maintaining a manned aircraft presence.

All of these applications – and many others – rely on a range of technologies. Some have emerged in recent years, while others are developments that have been ongoing for decades. The trend towards cheaper, lighter systems continues, which in turn will make more capable drones available at an ever more affordable price.

Drone Technology

The majority of drones are aircraft, or aircraft-type devices. These fall into two broad categories – rotorcraft and winged aircraft. The latter do not necessarily need to be powered – a suitably constructed glider drone could stay aloft for a very considerable time – but most use an engine.

The vast majority of winged drones – and all of them outside of the military – use a propeller to provide motive power. This could be driven by an internal combustion engine, but that is only practical on larger drones. Such drones are also prone to be noisy and may pose a hazard in the event of a crash. Legislation regulating electrically powered drones is far more likely to be agreed than a body of law allowing private citizens to send airborne fire hazards anywhere they want to – or anywhere their incompetence takes them!

Thus the majority of winged drones use one or more propellers driven by electric motors. The propellers may be mounted in a ‘tractor’ configuration, i.e. positioned to pull the drone through the air, but ‘pusher’ types are very common. A pusher propeller is, naturally, located on the rear of the drone or its wings. This has the