Drones are increasingly finding a natural home right across the survey industry, from asset inspection to BIM modelling and topographical data capture.

The technology has developed rapidly too, and giant leaps are being made from one product release to the next. Purchasing a drone can be a daunting experience as there’s always the concern that the model you buy will soon be eclipsed by much-improved versions.

As with any precision equipment, matching the tool to the task is critical too. So how should you go about investing wisely in a drone survey solution?

Here are our top six things to consider before you part with your cash.

  1. Your flying expertise
  2. Cost
  3. Payload capabilities
  4. Flying capabilities
  5. Practicality
  6. Airworthiness

In this first part of our guide on choosing a drone, we start at the top of the list.

1. Your flying expertise

Beginner

Before you invest serious money in a drone, it’s a good idea to buy a trainer model.

Some people opt for more expensive drones with advanced safety features built in. While these will protect the drone in the event of a mishap, we believe that crashing, rebuilding and getting back into flying a drone is a valuable experience.

As humans, we naturally trust reliable things. And, as drones have become ever more capable, many pilots develop a false sense of their skill, which in turn, can give them a feeling of invincibility.

We’ve seen unhappy outcomes like this on a number of occasions. An over-ambitious first purchase leads to an intimidating flying experience and a fear of losing the aircraft. Worse still, an early crash and considerable expense to the business.

We recommend having this experience early in your drone flying career and at minimal financial pain. That way, you’ll learn first-hand that this technology is fallible – without breaking the bank.

We don’t believe people fly dangerously on purpose all the time – just that they’re not fully aware of the dangers until it is too late.

So, to begin with, look for a drone that’s cheap, will bounce well and that you can use safely indoors. This will allow you to practice whatever the weather (though beware of winds if you do go outside). Good trainer drones include:

Multi-rotor

Fixed wing

And if you’re coming to HALO for your professional training, we’ll include a free trainer drone with your course package.

Reluctant pilot

If your interest in drones is out of necessity rather than keenness, then join us on one our introductory drone experience days or commercial drone instructor sessions.

Try before you buy with HALO

We have a range of drones you can use before you take the plunge and make your first purchase. With our help, you’ll develop the skills and confidence you’ll need to fly safely and proficiently and prepare you for handling larger drones.

All our trainer drones have dual controls, so you won’t need to worry about things getting out of hand!

Developing your drone skills

Once you’ve mastered the basics of drone piloting on a smaller aircraft, you’ll be ready to consider larger models. Typical progression would follow something like:

  1. DJI Tello
  2. DJI Mavic or Phantom
  3. DJI Inspire
  4. DJI Matrice 200 series or 600

Why DJI?

DJI is the most popular drone brand on the market. Its range covers the majority of weight categories and uses, so they’re good for gaining a broad level of flying experience.

However, DJI does not currently make fixed-wing drones, so you’ll need to look to companies such as Parrot and Wingtra for that technology.

2. Cost

When setting your budget, consider how ready you are to adopt drones.

Immediate need

If you’re a business and your customers are demanding drone capabilities, budget for a drone that will fit your commercial needs and reduce your investment in progression drones.

Costing your equipment against the likely returns is critical. Your customers will likely not care how you achieve the results – it’s the data and analysis they are concerned with. So, weigh up the likely costs against the likely benefits you’ll be able to sell to your customer, whether it’s increased efficiency, or delivery of data you wouldn’t otherwise be able to offer.

If the numbers add up, you could well be investing something in the region of £20,000 on a high-end solution, and to protect your investment we advise taking some professional instruction.

Remember, training with a HALO professional will help you build the skills and confidence you need both before and after you make that purchase.

The evaluation stage

If your need for drones isn’t pressing or you’re exploring the opportunities they offer, aim to minimise your initial outlay while getting as close to the key capabilities you think you’ll need.

For real value for money, it is hard to compete with what DJI offers as an integrated system. Building kit drones will probably cost you more and leave you with less functionality. DJI has done an amazing job of pricing its drones so they swamp the market and kill off most of the competition. 3DR, GoPro and Yuneec have all tried to secure footholds in the market, yet only one of them is still left in the game.

We’ve looked at how your flying expertise and budget may influence your choice of drone, so now we’ll consider two key aspects of drones themselves: payload and flying capabilities.

3. Payload

A mistake many people make when buying a drone is to focus too much on its flying capabilities and not enough on its payload capabilities.

Payloads include any form of sensor or object the aircraft is designed to carry. In the majority of cases, operators use conventional cameras. The technical capabilities of cameras to consider include the sensor, lens and field of view, ISO range, shutter speed, resolution, bit rate, and so on. You may also be looking at capabilities such as infra-red, NDVI (for agricultural work) and even LIDAR.

How important your drone’s payload capabilities are will depend greatly on how you prioritise other factors. For instance, there’s always a compromise between portability and the quality of the sensor. It boils down to what’s more important for you and your clients.

A drone with a slick design and a top speed of 80mph may look cool, yet could prove completely useless for your needs.

Sensor capabilities will also determine how easily you’ll be able to complete certain types of work. The DJI Inspire 2, for example, lacks the portability of the Phantom or Mavic, but makes it easy to changes lenses and even the camera itself. This, in turn, enables you to capture close-up imagery using a zoom lens, while increasing your stand-off from objects you need to avoid.

Similarly, the Matrice 200 series offers a degree of protection both from the elements and electromagnetic interference, as well as the potential to carry two sensors simultaneously (perhaps a standard RGB camera alongside an infrared sensor).

Again, we believe there’s a drone in the DJI range for most multirotor needs, unless your application or payload requirement is highly specialised.

Fixed-wing aircraft offer a similarly wide range of payloads, and the sensor configuration can generally be selected at the time of purchase. Drones such as the Wingtra platform offer a modular system, allowing quick swapping between, say, a DSLR, infra-red and multispectral camera systems.

To customise or not to customise?

Another option is to look at a custom/kit drone. There are companies that can make anything fly but bear in mind that customisation has its downsides. Firstly, bespoke drones can be bulky. Secondly, as systems integration is not seamless, you may need to add ancillary systems. This will, of course, add to your costs and potentially reduce the overall reliability of your drone. However, where the application is very specific or unusual, a bespoke build can give a competitive edge.

4. Flying capabilities

Do you want a drone that can gather high-resolution stills imagery for asset inspection, cover large areas of ground for mapping, or even fly in confined spaces? The task will dictate the type of aircraft you’ll need.

Flight time

Fixed wing drones, which generally offer longer flight times than multirotors, are the natural choice for surveying large areas. However, they are generally considerably more expensive to purchase, and also relatively easy to damage in the process of launch and recovery.

Flying characteristics

A drone’s efficiency and manoeuvrability need to match its intended use.

A fixed-wing drone cannot hover which limits its suitability for detailed asset inspection. However, this class of drone is unrivalled when attempting to cover large areas for mapping.

Multirotor drones equipped with large, slow-rotating, energy efficient motors can fly for a long time and carry specialist payloads. However, the price of this efficiency is manoeuvrability and also increased risk to those on the ground in the event of failure.

For survey work, the smallest drone capable of flying the payload required for the task is generally going to be the most cost-effective and practical.

Additional functionality and flight modes

GPS mode (P-mode for DJI drones) will significantly reduce the direct control you have over the drone. Think of it as a kind of cruise control, similar to that in many cars. You may struggle without it though, so it can be empowering. Our advice to you is to avoid relying on it to too much and focus instead on developing your pilot skills. This will also enable you to capture better footage as GPS mode can have limitations.

Stabilised mode (A-mode or Atti for DJI) stops the aircraft from self-positioning and gives you greater control. It’s a backup for when GPS fails, but we recommend familiarising yourself with this mode if it’s available as it will force you to improve your piloting skills.

Waypoint modes are used for autonomous capture of data according to a pre-programmed route. In many cases, the optimum flight path will be plotted even before leaving base and uploaded to the drone ready for flight. Most fixed-wing aircraft will rely on waypoints and similar autonomous modes rather than manual control.

For multirotors, waypoint flying is invaluable for ground surveying work while asset inspection may well see the pilot revert to manual flying.

Survey extras

For any serious mapping or topographical work, you’ll be looking to improve accuracy through ground control and possibly an enhanced GPS system. There’s nothing to stop you integrating your existing ground control solution into a drone workflow, but systems such as Propeller’s Aeropoint PPK kit can speed up the process considerably.

An RTK add-on for your drone is an option too, available on aircraft like the Sensefly eBee X and now on DJI multirotors too, with a lot of attention grabbed recently by a new RTK option on the Phantom 4. The DJI option comes with a choice of operating modes too: either a PPK post-processed workflow or RTK with an on-site base station.

So far, we’ve looked at four key considerations that will affect your choice of drone: how your flying expertise and the cost of drones play into the purchasing decision and payload capabilities and flying capabilities of the drone itself.

Finally, we consider the last two points on our list: practicality and airworthiness.

5. Practicality

The size of your drone will affect not only the size of the vehicle you’ll need, but also the logistics of moving it around on-site. As large drones can be very cumbersome, modern smaller drones are becoming increasingly popular.

Drone practicality includes considerations such as:

  • Size and ground clearance. This will determine how easy it’ll be to find a place to take off and land, which is easier said than done. Some drones, especially the smaller examples such as the DJI Mavic, require a landing pad to keep the propellers clear of objects and debris, negating the seeming practicality of their transportability.
  • Take-off and recovery limitations. Many fixed-wing drones require a considerable area for landing (for take-off they can generally be launched directly into the air). If you expect to be operating from small spaces it might be worth considering a system with VTOL (Vertical Take-off and Landing) capability.
  • System integration. How important to you is it that everything comes in one box, ready to work seamlessly together? This is of particular importance when considering bespoke payloads and ground-control options.
  • Battery power limits. This is particularly important if you’re planning to use your drone abroad as there are transport limitations on carrying high-capacity batteries.
  • Weather resistance. How well will your drone stand up to heavy winds and rain? For most creative applications, rain on the lens is a showstopper, so consider how you’ll be using your drone carefully before committing to a purchase.
  • Indoor capability. Most drones are either challenging or not practical at all when working in confined spaces. However, there is an increasing choice of specialist hardware in this area including the Flyability Elios and the newly announced ATyges FV0. It’s even now possible to buy cages for off the shelf drones like the DJI Phantom 4.

6. Airworthiness

Airworthiness is how we term the aircraft’s overall suitability for safe flight.

In manned aviation, airworthiness is dictated by industry standards set by the regulators. However, there are no airworthiness requirements for drones weighing less than 20kg. This means the reliability of the aircraft you’ll be operating will depend on its design specification and quality of manufacture.

As with everything, manufacturing quality across the drone industry varies. However, the general standard is high and if you opt for a well-known brand, you won’t go far wrong. That said, even the most costly drones are not immune from failure, and it’s important to consider the consequences of an unexpected event. This may affect your choice of size of drone, and the decision between multirotor and fixed-wing options.

Single points of failure

An important consideration is “single points of failure”. This relates to any component that could disable the whole system if it fails.

Multirotor drones, especially quadrotors, have many single points of failure. If just one motor or propeller on a multirotor fails, the whole system falls out of the sky.

Manufacturers solve this problem by various means. Some develop incredibly reliable motors, which push costs up. Others add additional motors and duplicate other vital components such as the flight controller and other navigational systems.

Fixed-wing drones often find favour through their apparent ability to glide to safety. But beware – although they most likely will glide, there is increasingly no way to control a fixed-wing drone manually so critical failures will still most likely result in a crash and consequential damage/injury.

Common problems

For most applications, DJI multirotor equipment is reliable enough, though there can be bad batches of each model and common problems. These are usually more to do with the operation of the camera, gimbal (the pivot that the camera rotates on) or downlink (which transmits data from the drone to other devices). Bear in mind, however, that DJI prefers to stick with four motors, so there’s always a risk if one fails.

Intermittent failures can be costly as well as embarrassing in the presence of a client, so avoid buying too cheaply.

Safety

Safety is key, particularly in sensitive environments. In some cases, you may have to compromise some of the drone’s capabilities to maintain optimum reliability. Some industries set their own standards for governing drone use.

High-risk environments, for example, rail infrastructure and nuclear installations, are particularly concerned about the airworthiness of drones. Bare-earth sites, perhaps in the setting-out phase, generally present fewer requirements.

DJI is considered a producer of pro-consumer drones. Its new range of enterprise drones takes this a step further while focusing on the capabilities and payload of the range, rather than airworthiness. Like the company’s other drones, the enterprise models are of good quality, yet limited to four motors.

For greater proof of airworthiness, the Ascending Technologies Falcon 8 is the class leader. It has multiple redundancy and the manufacturer provides evidence of its airworthiness. You can use this to secure permission to fly in sensitive locations.

HALO recommends:

The DJI Phantom 4 has impressive sensor characteristics for its size and cost but doesn’t allow interchangeability of lenses and camera. For many, however, its practicality and size more than compensate for this lack of flexibility. Phantoms offer great starting points and platforms to build on – and good backups should your future primary drone fail.

Hopefully, now you’ll have the knowledge and confidence to identify the right drone for you.

If you’d like any specific advice or would like to learn more about how HALO can help you get the very best from your drone, contact us today.

Posted on: February 1, 2019