Drone Soccer FAQ

Two teams of up to five drones play three sets of three minutes. Only the striker can score, by flying through the other team's hoop.

• Each team has one striker, marked so referees and opponents can tell which drone it is. The others defend, block and clear space.
• After a goal, the scoring team must retreat behind the half-court line before it can score again.
• The team that wins two of the three sets wins the match. Some events add sudden-death overtime.
• If a striker's tag falls off and the striker can no longer be identified, goals scored after that don't count.

Sources: U.S. Drone Soccer rules · FAI F9A drone soccer rules · UK Drone Soccer rules · Class 20 rulebook

Most school programs start with Class 20. It is smaller, lighter and cheaper, and fits a smaller indoor arena.

• The class number is the ball's diameter in centimetres. Class 40 balls must measure 40 cm ± 2 cm.
• One Class 20 kit lists 100 g with battery and about 6 minutes of flight.
• Class 40 drones are larger and hit harder, which suits older pilots and bigger arenas.

Sources: Class 40 rulebook · FIDA USA Class 20 kit · FAI Drone Sports

Not for flying inside a netted indoor arena. Anyone who flies recreationally outdoors must pass the FAA's free TRUST test first.

• The REC Foundation says TRUST isn't required for its indoor drone competition, but encourages it as safety training.
• U.S. Drone Soccer's student program includes an AMA-hosted safety course that covers TRUST topics.
• TRUST takes under an hour online and never expires, so many coaches have every student take it.

Sources: REC Foundation: What is TRUST? · AMA: U.S. Drone Soccer student leagues

Expect roughly $350 to $600 per drone kit, plus batteries, spares and an arena. A full starter program with an arena runs well over $10,000.

Budget for ongoing parts too. One school-drone supplier estimates about $495 a year in spares for a 12-drone program after the first year.

Sources: listed sellers above · FTW Robotics: cost of a school drone program. Prices as listed when checked; confirm before ordering.

Plan on about 4 to 6 minutes per battery and at least three batteries per drone, so one set flies while another charges.

• Starter kits usually ship with 3 batteries each. A Class 20 kit lists about 6 minutes; smaller beginner balls about 4.
• A three-minute set plus warm-up uses most of a pack, so your coach swaps batteries between sets.
• Chargers limit practice more than drones do. Buy enough charging ports to keep up with the number of drones flying.
• Pilots: batteries stay with your coach. You never charge, plug in or unplug a drone battery.
• Coaches: never charge unattended, store packs at about 3.8 V per cell, and retire puffed or damaged packs.

Sources: FIDA USA Class 20 kit · Drone Sports program overview · 100 mm drone soccer ball · Ohio State: starting a scholastic drone team

Angle mode. The drone levels itself when the sticks are centered and can't tip past a set angle, which keeps a ball drone from rolling over.

• Set Angle mode on a switch in Betaflight's Modes tab, or make it always on for first sessions. Betaflight 101, module 5 walks through it.
• Lower the angle limit for new pilots so the drone leans less and moves slower.
• Coaches running first sessions often use a beginner profile that also caps throttle and rates; first-time pilots rarely succeed on competition settings.
• Acro gives full control and is what many strong strikers move to, but only after hours of practice.

Sources: Oscar Liang: Betaflight modes · Oscar Liang: Angle mode settings for small drones · Drone Sports: running a demonstration · Hackaday: ball drone angle limits

Betaflight tells you why. Read the arming disable flags in the Setup tab, or type status in the CLI.

• THROTTLE: throttle isn't fully down. It must read below 1050 in the Receiver tab.
• ANGLE: the drone is tilted. Set it level on the floor.
• RXLOSS: no radio signal. Turn the radio on and check binding.
• ARMSWITCH: the arm switch was on at power-up. Flip it off, then on.
• MSP: you're plugged into the computer. That's normal on USB.

No computer? Count the beeps: the flag number is 5 × long beeps + short beeps. The full flag table is in Betaflight 101, module 9.

Sources: Oscar Liang: quad arming issues · SpeedyBee: when a drone can't be armed · Betaflight: arming sequence and safety

Drift is usually an accelerometer that needs calibrating. An instant flip is usually motor order, motor direction or props on the wrong motors.

1. Put the drone on a level surface and click Calibrate Accelerometer in the Setup tab.
2. Tilt and turn the drone and check the 3D model follows. If not, fix board alignment in the Configuration tab.
3. Check each prop is on the right motor for its spin direction (the motor map is in Betaflight 101, module 6), and ask your coach to check motor order and direction.
4. Check props for chips and bends, and check the cage hasn't shifted the flight controller after a hard hit.
5. Only after all that, consider accelerometer trims. Don't change PIDs to fix drift.

Sources: Unmanned Tech: fixing drift in Angle mode · ThinkRobotics: Betaflight setup for beginners

Props, then motors, then cage and frame pieces. Keep a parts bin and teach students to do their own repairs.

• Starter bundles often include enough spare props and motors to get a program through its first year.
• Keep spare props for every drone, a few motors, cage pieces, battery straps and zip ties.
• A soldering station and someone trained to use it save weeks of waiting on replacements. Solder 101 covers it.
• After any repair, recheck motor order and direction and recalibrate the accelerometer before flying.

Sources: Drone Sports program overview · FIDA USA spare parts · FTW Robotics

On ExpressLRS, the easiest way is to give the radio and the drone the same binding phrase. Then they link whenever both are on.

1. Set the binding phrase in the radio's ExpressLRS settings.
2. Ask your coach to power the drone, then wait for the receiver to start its own WiFi network (usually about a minute without a radio link).
3. Join that network from a phone or laptop, open 10.0.0.1 in a browser, and enter the same binding phrase.
4. A solid receiver light means it's linked. Check in Betaflight's Receiver tab that every stick moves its own bar.

Coaches: give each team its own binding phrase so pilots can't control each other's drones by accident.

Sources: Oscar Liang: binding an ELRS receiver. Steps differ for other radio systems; follow your drone's manual.