Indoor drones
An indoor drone is a drone light enough and slow enough to be flown inside a room without damaging the room, the aircraft or the person flying it, which in practice means a machine of a few tens of grams with guards round its propellers and a way of holding position that does not rely on satellites. Satellite positioning is the part most buyers do not expect. The signal that lets an aircraft sit motionless over a lawn is blocked or scattered by a roof, so an indoor machine either holds itself steady by looking at the floor or does not hold itself steady at all.
Where this class sits
Typical take-off weights for this class, on the same scale used on every class page, so the twelve can be read against one another. The only figure here with legal force is the 250 gram line.
What an indoor drone actually is
An indoor drone is a small multirotor, usually between about twenty and one hundred grams, built so that a collision is an event rather than a repair. The propellers sit inside guards or inside ducts, the frame is moulded plastic or foam rather than carbon, and the motors are often brushed rather than brushless, which makes them cheap, quiet and short lived. Flight times are short by the standards of the hobby, because the battery is small and there is nowhere to put a bigger one, and a single pack is usually spent in a handful of minutes rather than the 15 to 25 minutes an outdoor camera machine gives.
The class overlaps heavily with toy drones and with the smallest end of the mini and foldable market, and the overlap is real rather than a filing problem: many aircraft sold as indoor are toys, and some machines sold as mini drones will fly indoors perfectly well in a large enough room. The definition that separates them is not size but energy, and that is the next section. What a drone actually is covers the senses of the word itself.
What separates an indoor drone from the rest
What separates an indoor drone from the rest is mass, and everything else in the class, the guards and the absence of satellite positioning included, follows from keeping it low. A machine at the light end of that twenty to one hundred gram range that hits a wall at walking pace transfers very little energy: the guard flexes, the aircraft falls, and it is flyable again once it is picked up. The same collision with a 250 g machine chips plaster and breaks propellers, and with anything heavier it breaks the aircraft. Low mass is also what makes the class survivable in a room with people in it, because the propellers are small and they are behind guards.
The second consequence is positional. Outdoors, an aircraft holds station using a satellite fix; indoors that fix is unavailable or, worse, partial. A partial fix is more dangerous than none, because the aircraft believes a position that is wrong and moves steadily towards it, so most flight controllers refuse to enter satellite hold indoors and fall back on other sensors. Those sensors are a barometer for height, a downward facing camera doing optical flow, which measures how the floor is sliding underneath, and often a short range infrared or laser rangefinder. They work well on a patterned carpet in good light and badly on a plain glossy floor in the dark, which is why the same aircraft is rock steady in one room and wanders in the next.
What an indoor drone costs
Indoor drones occupy the cheapest bands on the site and the steps between them are unusually clear. Under thirty pounds buys a palm sized toy with brushed motors, guards, no camera worth the name and no position hold: it holds height roughly and drifts constantly, so it has to be flown every second it is airborne. The band from about fifty to one hundred and fifty pounds adds the thing that changes the experience, which is optical flow position hold, along with a camera that produces a usable picture in daylight and a battery system with more than one pack. Above that, you are buying an outdoor aircraft that happens to be small, with a gimbal and a satellite receiver that will be switched off for the whole of an indoor flight.
Paying more stops changing indoor flying at the point where position hold works. There is no third tier of indoor performance to buy, because the limit is the room, not the machine. The one exception worth the money at any band is spare parts: propellers, guards and batteries, which are consumed rather than owned.
What to check before buying an indoor drone
- Confirm the propeller guards are fitted as standard and not sold as an accessory.
- Check whether the aircraft holds position with a downward camera, or only holds height.
- Weigh it: anything comfortably under 250 g is in the light class, and most of this market is far below it.
- Check whether the motors are brushed or brushless, and accept that brushed motors are a consumable.
- Count the batteries included and find out whether spares are sold separately.
- Check how it charges, since a pack is a few minutes of flying and then an hour on charge.
- Check whether it has a beginner mode that limits speed and angle.
- Check the controller: a real transmitter with sticks is easier to fly accurately than a phone screen.
- Measure the room, because a machine that needs three metres to stop is not an indoor machine in a small kitchen.
What flying an indoor drone is like
The first ten minutes indoors are a sequence of drift, correction, overcorrection and a wall. A small multirotor in an enclosed space is flying in its own disturbed air: the downwash bounces off the floor, comes back off the walls, and pushes the aircraft around in ways that have no equivalent outside. Close to the floor it sits on a cushion of its own air and refuses to descend smoothly; close to the ceiling it is pulled up and sticks there. Both effects surprise every new pilot, and both are the reason the middle of the room is the only comfortable place to be.
What indoor flying rewards is small inputs, and what it punishes is panic. The instinctive reaction to an aircraft heading for a bookcase is to pull back hard, which on most machines makes it climb and continue. The habit worth building in the first session is to cut the throttle instead: a sixty gram aircraft dropping onto a carpet is undamaged, and a sixty gram aircraft flown into a bookcase at speed usually is not. Practising indoors is also the fastest way to learn orientation, because the aircraft comes back towards you constantly and you have to fly it while it is facing you, which is the skill that outdoor flying never forces.
Caution
Small propellers turn fast enough to cut, and indoors they are at face height in a space with people, pets and furniture in it. Fly with the guards on, keep cats and dogs out of the room, and never catch the aircraft out of the air by hand. Charge the battery on a hard surface away from bedding and paper, and stop using a pack that has swollen or been crushed in a crash.
The UK rules that apply to indoor drones
Indoor drones nearly all sit well under the 250 g boundary the scheme uses to divide the lightest machines from the rest, and that boundary, along with whether the aircraft carries a camera, is what decides which requirements attach to it. The Civil Aviation Authority is the body that publishes those requirements, including how flying inside a building is treated and how the toy category is defined, and it also publishes the 400 foot ceiling and the sight requirement that govern outdoor flight. Those requirements change, so they should be read at the source before flying rather than taken from a product listing or from this page.
Indoor drones against the alternatives
Three sibling classes are the better answer in situations people arrive at this one with. If the goal is to learn to fly properly, the small FPV machines flown indoors, the class covered by FPV and racing drones, are a better purchase than any camera toy: they are the same size, they are built to be crashed and rebuilt, and they teach control rather than letting the software hold the aircraft up. If the goal is a picture of anything, an indoor machine will disappoint, because the sensor is tiny and indoor light is far darker than it looks: Camera drones is the honest place to start instead. And if the machine is a present for a young child who will fly it twice, a toy drone at the bottom band is the right buy and paying for optical flow is money wasted.
The smallest machines, where to fly indoors, and why the searches say Singapore
The smallest indoor drones are palm sized, weigh in the low tens of grams, and fit inside a hand with the guards on. They are genuinely flyable and they are genuinely limited: at that mass, a draught from an open door is a wind, a warm radiator produces a current the aircraft rides, and flight times are counted in minutes. The trade is worth making for the smallest rooms and for flying around people, and it is not worth making in a hall, where a slightly larger machine will hold position far better.
Somewhere to fly indoors is harder to find in the United Kingdom than the searches suggest. There is no network of public indoor drone venues here in the way there is for other hobbies. What exists in practice is sports halls, scout huts and village halls hired by model flying and small FPV groups for evening sessions, usually through a club rather than as a walk in booking, and occasional organised race meetings in warehouse space. Searches for indoor flying centres in Singapore surface constantly because the search term is shared, but nothing about how flying is regulated there transfers to the United Kingdom, where the Civil Aviation Authority sets the requirements.
The other search this class attracts is for the cheap toy drone bought from a high street catalogue shop or a supermarket at Christmas. Those machines are real indoor drones, they are the bottom band described above, and the two things worth knowing before one arrives are that the battery is soldered in on some of them and that the spare propellers are the only part that will ever need replacing.
Is an indoor drone the right buy for you?
Yes, if you want to fly regularly in winter and have a room with clear floor space. The class suits somebody who wants stick time rather than footage, somebody buying a first aircraft for a child under supervision, and somebody who already flies outdoors and wants something to practise orientation with when the weather has been wrong for three weeks. It is the wrong buy for a reader who wants aerial photographs, for a reader whose only space is a small flat with a glass coffee table, and for a reader who imagines a small machine is a safe machine: it is safer, not safe, and the difference is a pair of guards.