What XXYY means
Every FPV motor has a 4-digit designation like 2809. The first two digits are the stator diameter in mm. The last two are the stator height in mm.
Bigger stator = more copper = more torque = can swing a bigger prop. For a 7" drone carrying a Jetson Orin companion computer, you need a large stator that generates enough torque to push a 7" prop at reasonable RPM without overheating.
The 2809 is a cinelifter-grade stator — 28mm wide, 9mm tall. It was designed for camera drones with heavy payloads. That's exactly what our AI guard drone is.
Motor size reference
| Motor | Stator | KV Range | Props | Cells | Best for |
|---|---|---|---|---|---|
| 1408 | 14mm × 8mm | 3600–4500KV | 3″ | 3–4S | Micro / Toothpick |
| 2207 | 22mm × 7mm | 1750–2400KV | 5″ | 4–6S | Racing / Freestyle |
| 2306 | 23mm × 6mm | 1700–2500KV | 4–5″ | 4–6S | Freestyle / Urban |
| 2809 Our Pick | 28mm × 9mm | 1050–1400KV | 6–7″ | 6S | Heavy Lift / AI Drone |
| 3115 | 31mm × 15mm | 900–1100KV | 7–8″ | 6–8S | Cinelifter / Cargo |
KV is RPM per volt — match it to your cells
KV means the motor spins at that many RPM for every volt applied. Higher KV on more voltage = faster RPM = smaller props needed. Lower KV on lower voltage = slower RPM = bigger props = more torque. The rule: lower cell count → higher KV, higher cell count → lower KV.
Thrust-to-weight ratio
T:W ratio is total thrust divided by all-up weight. Minimum viable is 2:1 — the drone can hover at 50% throttle. For autonomous flight with GPS and a companion computer, aim for 2.5:1 or higher to handle payload variance and wind.
Our 7" guard drone fully loaded (frame + FC + ESC + Jetson + GPS + battery) is roughly 1.8–2.0 kg. The four 2809 motors at full throttle produce approximately 4.8–5.2 kg total thrust on 7" props at 6S. That's ~2.5:1 — solid for autonomous patrol.
Our motor choice for the 7″ guard drone
iFlight Xing2 2809 1250KV Motors (4-Pack)
Our exact motors. 2809 stator, 1250KV, rated for 6S. Handles 7" props + Jetson Orin payload at 2.5:1 thrust-to-weight. Buy 5 — one spare is mandatory on a build this complex.
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Tattu R-Line V4.0 6S 1300mAh 130C (2-Pack)
Matched to our 2809 motors. 6S, 1300mAh, 130C — at 40A average draw, we see 8–12 min patrol flight times. The cell count has to match your motor KV.
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