DRONE REPAIR

Tello is a quadcopter. It has four propellers that spin to generate an upward force. Two of the propellers spin clockwise, while the other two spin counterclockwise. The propellers that spin clockwise are shaped differently than the propellers that spin counterclockwise. The propellers need to be placed properly for Tello to fly.

See pages 3 and 4 of the Drone Legends Operations Manual for more information.

If your Tello’s propellers aren’t spinning, the propeller guards might be in the way. Gently adjust the guards so they don’t obstruct the propellers. This ensures free movement and proper lift. However, if the guards are broken, it’s essential to have your drone repaired for safe flying. Damaged guards can compromise both safety and drone performance.

If your drone is acting a bit odd, it might just need a quick calibration:

• Your Operations Manual (page 41, under “The Tello’s internal IMU” section) walks you through how to calibrate your IMU (Inertial Measurement Unit).
• Or, you can do this directly in the Tello App: Go to settings > more > … > calibrate IMU in the Tello App

If your Tello shows a warning (Error Code 13) or feels hot, it’s overheated and shouldn’t be used.

Let the drone and battery cool down completely before using it again. Extended use, particularly in heat, can cause overheating. For prevention, take regular breaks during flights.

The two black spheres on the bottom of Tello that control Tello’s altitude. Tello uses these sensors to hover about 4 feet above the ground upon taking off. The VPS should be wiped clean periodically, like a camera lens. If it’s dirty, it can malfunction. The VPS consists of a camera and an infrared sensor. Both serve to stabilize the drone in order to hold a certain position when moved to it.

To keep your drone running smoothly, a stable connection is key. If it’s not stable, you might find the drone hard to handle or it could stop working altogether. Check out these steps to make sure you’ve got a strong connection going.

• Update the DJI Tello firmware using the DJI app
• SSID (Service Set Identifier): the technical name for a Wi-Fi network. Tello creates its own Wi-Fi hotspot that connects to a device and allows for remote control.
• Compatibility – Tello App or DroneBlocks App
• iOS – Requires iOS 9.0 or later.
• Android – Android version 4.4.0 or later.
• Be sure you have enough bandwidth and space to support the number of tablets/computers and Tellos you are using simultaneously.
• Turn Tello off before connecting to a new device.
• If Tello fails to connect, shut down the app, turn off Tello, connect to your regular Wi-Fi to re-launch, and repeat the connectivity sequence from “Connect to Tello”. This sequence must be followed exactly.
• In some cases, the Wi-Fi connection between your mobile device and Tello may drop. If this happens, DroneBlocks can no longer issue commands to Tello. Do not panic! Tello will execute the last issued command and then hover in place. At this point, you can toggle into your Wi-Fi settings and reconnect to Tello, then open the DroneBlocks app again and resume the regular Tello connection process.
• In rare cases, Tello may stop responding to DroneBlocks commands and will hover in the air. Try inserting a land block, then tap launch mission. You can also close DroneBlocks and switch to the Tello app to regain manual control, going through the connection process again.
• If you still are unable to connect to DroneBlocks, the great news is that Tello has an internal battery threshold. Once this gets to a critical state Tello will land automatically.
• Skipped DroneBlocks commands
• If you notice DroneBlocks commands are being skipped and cannot determine the cause, first check that your software and firmware are updated, then check your battery level.
• If this problem continues, try adding a “hover” block between commands. Occasionally, commands may be sent too quickly for Tello to respond. Adding a block such as “hover” may give Tello time to better process the command.

Noted in the flying conditions earlier, it is important to also remove or minimize any interference that impacts the performance of your drone. Here are some things to consider that cause interference with your drone operation.

• Tello uses sensors instead of GPS. Sometimes you may notice unexpected behavior by Tello which could be caused by a number of obstacles. People, especially if many students are standing in close proximity to Tello, can cause obstacle avoidance. Set boundaries in class for safety and to reduce interference.
• Metal or rebar in the ceiling, floor, metal light fixtures, tables, or chairs can cause Tello to behave oddly. If you notice this issue, reconfigure your mission commands to prohibit Tello from flying low to the ground, near light fixtures, or other objects that may contain metal and cause interference.
• Stone, concrete, reflective, or marble flooring or walls may cause some interference issues. We notice that wooden gym floors work the best if flying missions close to the ground. If you notice your Tello seems to become stuck about 10-15 inches from the ground, reconfigure your code to fly at a higher altitude.
• Have a clear flight path available. If you choose to fly near or through obstacles as part of an activity, use plastic goalposts or rings, as plastic will provide the least interference.