In Waypoint’s regular segment, Ask Andrea, senseFly’s Product and Training Manager, Andrea Blindenbacher, answers questions on launching and landing a mapping drone, such as why it’s important to take off and land against the wind and what do if something unexpected happens during your landing approach.
Question: How do I successfully launch a mapping drone?
I get this question a lot, and with fixed-wing drones, such as the eBee X fixed-wing drone, it’s important to remember that takeoffs are linear, just like an airplane.
Remember that you always want to try and take off against the wind, which allows the aircraft to climb. With tailwind, the plane, in our case the mapping drone, is pushed toward the ground and has a harder time gaining altitude.
Another thing to remember is that the angle of the aircraft the moment it takes off—the angle of attack—is important. With the eBee X, that angle should be 45 degrees. At this angle, air flows around the wings and the aircraft is basically sucked up into the air. Here is a link to a diagram that provides a good example of this.
The transition altitude is another factor that contributes to a successful launch. This is the altitude at which an eBee stops its linear climb and begins to make its way to the starting waypoint, which is defined in senseFly’s eMotion drone flight software.
By default, this is set at 20 m (66 ft) Above Take Off (ATO). It can be useful to increase this transition altitude to 30 m or even 40 m (98 and 131 ft, respectively) to make sure that one clears all potential obstacles once the eBee gets to its starting waypoint, which it can do by turning either left or right. These could be anything from trees and buildings to powerlines and other man-made obstacles.
One helpful tip I like to give people is that it’s also possible to force a directional launch, meaning that the eBee follows one exact line, without adapting to slight changes in wind direction, until it reaches the transition altitude desired.
Question: What makes a successful landing?
Of course, we always want the mapping drone to come back down safely, so an important concept to understand when it comes to landing is that the home waypoint and landing position are linked.
The home waypoint is always located in the air and is set to 75 m (246 ft) ATO in eMotion by default, while the landing position is on the ground at 0 m ATO. Therefore, moving the home waypoint changes the landing position.
Once the drone comes back down for landing it will depart doing a downwind leg, turn into the wind and start its descent at the landing position. Remember: this approach must face the wind (same with launching) because the wind helps it to slow down while maintaining its attitude and prevents it from rapidly descending.
This descent happens at a specific angle and is defined by the mapping drone’s configuration. Therefore, the start of the approach zone must be at a certain distance (around 250 m or 820 ft) from the landing position. This is set by default in senseFly’s eMotion flight-planning software and cannot be changed by the user. It’s also best to choose an obstacle-free trajectory for the last 60m (197 ft) of the approach, keeping the wind direction in mind.
Finally, the width of the approach zone can be defined more loosely. A large approach zone allows the eBee mapping drone to choose its trajectory (it will choose the most “wind-facing” trajectory). Conversely, a very narrow approach zone will force the drone to follow a certain trajectory. If not aligned correctly with the wind direction, this can lead to harder landings or side drift due to crosswind.
It’s also helpful to remember that if at any time it looks like your landing is off a little or isn’t going the way you want it to, or anything unexpected happens within the landing area, the procedure can be aborted using the control button “ABORT” or by simply hitting the spacebar on your keyboard.
Do you have drone-related questions for Andrea? Ask in the comments section below and your question might get featured in a future post.