Aviation photographer Katsuya Noguchi's abbreviation, I will bother you from the sky vol.16 "About the drone and the" wind "" | VIDEO SALON

vol.16 "About drones and" wind "" sentence ● Katsuya Noguchi (HEXaMedia)

* This series is a reprint of the content published in the May 2017 issue.

Spring is the season of "wind". The energy of solar radiation is getting stronger day by day, but in the spring when cold air still flows from the continent, the atmospheric condition becomes unstable, regular low pressure passes, and gusts blow. It's an easy season. I remember that there were many accidents in early spring when the motor paraglider crashed due to a sudden unstable wind.

A drone is a type of aircraft that floats in the air by scratching the air with a propeller. Naturally, it is greatly affected by the wind. Let's talk about how you can fly and why you should cancel your flight.

How strong can a drone fly?

The strength of the wind is generally expressed by the speed of the wind. In Japan, multiplying the number of speeds per second (distance traveled in 1 second [m]) by 3600 gives the general speed (time x distance [km]). 1m / s is 3.6km / h and 36km / h is 10m / s. A wind of 10 m / s can be read as a wind of 36 km / h.

I get a lot of questions, "How strong can a drone fly?" Early drones had poor motor and controller controls, which could easily turn the aircraft over in unstable winds. At that time, the drone said that the flight itself should be 7-8m / s or less, and the shooting should be 5m / s or less. Currently, with the exception of large drones, there is almost no concern that the aircraft will suddenly tip over during flight. Is it about 10m / s or less for flight alone and about 7m / s or less for shooting?

The wind speed is described in "m / sec (second speed)", but it is easier to imagine if it is replaced with "km / hour (speed)".

▲ The wind speed is described in seconds in Japan. Multiply the speed by 3600 to get the speed per hour. If it is 10m / s, it means that the wind of 36km / h is blowing. Since driving of a car etc. is expressed in speed, it will be easier to grasp the image if converted to speed.

However, this is a story of the drone's ability in the air, which is different from the pilot's skill. The points that pilots should be aware of in actual flights are behavior during takeoff and landing and altitude management.

At the time of takeoff and landing, the propeller rotation has not yet fully increased, and the ground and other obstacles are nearby, so the wind-swaying aircraft may come into contact with them. If it is absolutely necessary to fly in a strong wind, (1) take off using a windless area such as a building or the leeward of a large vehicle. ② Take off at an altitude of several meters. --- I think either of these is effective.

In any case, if you fly, it is recommended to watch the behavior of the aircraft for a while in the wind. In addition, hand catching and hand releasing after taking proper safety measures are also effective.

Winds generally tend to blow stronger at higher altitudes. Even if the wind is about 7 to 8 m / s on the ground, it is almost always blowing 10 m / s or more when it goes up to 100 m. If you feel that the wind speed near the ground is already close to the operational limit, refrain from raising the altitude.

Wind resistance that can be read from the spec sheet

Take DJI's Phantom4 Pro as an example. The spec sheet states that the maximum speed is 72km / h in Sport (S) mode, which emphasizes speed, and 50km / h in P mode, where GPS and obstacle sensors work effectively. This can be read as S mode 20m / s and P mode 13.9m / s.

In other words, if you fly in P mode in a wind of 14m / s, it means that you will not be able to return to the point of takeoff at the moment when it flows downwind even a little.

As the word "average wind speed" implies, the wind is not blowing at a constant speed. The wind speed may increase due to the influence of the terrain and buildings. Considering that, I think that a wind of about half to two-thirds of the performance announcement speed of each mode will be a guideline for the operational limit in the air.

Also, since the publication speed is the limit in terms of "flying", it should be considered depending on the skill whether the gimbal shakes due to the wind and whether or not the aerial shot can be taken as intended.

Propeller guard and wind

The propeller guard is effective for safety when shooting indoors without wind or at low altitude where the wind is weak and there are many obstacles. However, if a general propeller guard, that is, a shape that is easily exposed to wind at a place far from the center of gravity, is attached in four directions, it will itself receive the wind and become a factor that makes the aircraft unstable. I think it could happen. When the wind is strong, removing the propeller guard may stabilize the aircraft and reduce the risk of crashing.

Wind speed change due to terrain

Around mountains, cliffs, and obstacles in large buildings, the wind causes changes in the wind. The airflow rises on the windward side and falls on the leeward side. And a vortex is created by turbulence. The changes on the windward side are relatively mild, but the turbulence on the leeward side is sometimes so intense that the attitude and altitude of the aircraft cannot be maintained. Drone pilots need to keep an eye on wind strength, direction and terrain, and if possible, stay away from the leeward side.

The wind ... itself is invisible to the human eye, but the changes caused by the wind are often visible, such as the movement of trees and branches and leaves. It's not as easy to see as rain or sunshine, but it's the most important factor in the weather conditions when flying a drone, so keep an eye on the changes and try to fly safely.

Beware of changes in wind caused by the terrain

▲ Wind is a type of eddy. When a strong wind hits a building or a tree, a vortex as shown in the figure may occur on the leeward side or the leeward side of the mountaintop. It is desirable to understand these characteristics before flying in places where there are mountains, valleys, or large buildings.