Test du moteur Pi Thrust 3115-900KV : une poussée compacte pour les drones de cartographie et d'inspection en configuration 6S

Not every industrial drone needs a 43mm stator. The Pi Thrust 3115-900KV is built for a specific brief: maximum performance in a compact, lightweight motor that fits tight arm geometry without sacrificing build quality. With 4,600g peak thrust from a 31×15mm stator on a 10-inch propeller at 6S, this motor hits a sweet spot that larger motors can't reach — light enough to keep the airframe honest, powerful enough to carry real payloads on real missions. We've tested it across compact mapping quads, corridor inspection platforms, and security UAVs. Here's exactly what we found.

What the 3115 Stator Designation Actually Means

The number tells you the geometry. 31mm stator diameter keeps the rotating mass compact — less inertia, faster throttle response, and a smaller physical footprint on the arm. Meanwhile, the 15mm stator height provides enough winding depth to generate meaningful torque without pushing the motor into the same weight class as larger industrial units.

In practice, that combination gives you a motor rated at roughly 180g — roughly 35% lighter than the 4312-380KV. On a four-motor platform, that's over 400g saved in motors alone. For compact designs where battery and payload are competing for every gram, that margin matters directly.

Why 900KV and a 10-Inch Prop Is the Right Pairing at 6S

At 6S (22.2V nominal), a 900KV motor spins at approximately 19,980 RPM unloaded. A 10×4.5-inch carbon fiber propeller drops that to a loaded operating range of 14,000–17,000 RPM depending on throttle position — precisely the range where a 10-inch prop operates at peak aerodynamic efficiency. Step up to a higher-KV motor with the same prop and you overspeed the blade; step down and you lose the high-cadence response that makes compact platforms agile in tight environments. The 900KV figure isn't arbitrary — it's where the physics line up for this stator and prop combination.

Thrust and Efficiency Data — 6S Static Test, 10×4.5" CF Prop

We ran the 3115-900KV on a static thrust stand with a 10×4.5-inch carbon fiber propeller at 6S (22.2V). Throttle stepped from 10% to 100% in 10% increments, with a 30-second stabilization period at each step. Results below:

What the Numbers Tell You About Mission Planning

The efficiency peak lands at 30–40% throttle — 3.63–3.86 g/W — which is exactly where a well-loaded compact platform cruises during a grid survey or steady corridor inspection. That's not coincidence; it reflects how the winding is optimized for sustained mid-throttle output rather than sprint performance. In practice, this means your 10Ah 6S pack goes further per charge than you'd get from a motor tuned for peak thrust at full throttle.

At 70% throttle, the motor delivers 3,450g at 1,288W — a useful sustained operating point for wind-exposed or payload-critical missions where you need headroom without running the motor hot.

Best Applications for the 3115-900KV

Compact Mapping Quads (Sub-15 kg MTOW)

A four-motor platform running 3115-900KV motors generates 18,400g total static thrust. At a 2:1 thrust-to-weight ratio, that sets a safe operating MTOW of approximately 9.2 kg — enough for the airframe, a 10Ah 6S battery, and a compact RGB or multispectral camera. Notably, operators building mapping quads under 10 kg MTOW frequently prefer this configuration specifically because the lighter motors extend flight time on the same battery capacity. We've seen this setup achieve 28–34 minute endurance with a 10Ah 6S pack on a 4.8 kg airframe.

Corridor and Infrastructure Inspection Platforms

The 3115's compact diameter matters significantly in confined environments. Power line inspection, bridge underside surveys, and indoor facility checks all benefit from a motor that doesn't push the prop disc diameter beyond what the geometry allows. Similarly, the faster throttle response from the lower rotating mass makes station-keeping in gusty corridor conditions more precise — the flight controller has more authority over the airframe when the motors respond quickly. One inspection team we work with runs six 3115s on a hexacopter and specifically cites the motor's responsiveness as the reason they kept the configuration over switching to a four-motor 4312 setup.

Security and Surveillance UAVs

Security platforms prioritize loiter time, low acoustic signature, and reliable sustained operation over raw payload capacity. The 3115-900KV at 40–50% throttle produces a relatively quiet acoustic profile compared to high-KV motors running smaller props at higher RPM. Furthermore, the sustained efficiency at cruise means longer loiter on the same battery — relevant when you're maintaining a fixed-point observation orbit for 20–25 minutes without returning to base.

ESC and Propeller Pairing

Because peak current reaches 90.3A, you need an ESC rated for continuous 80A or above with burst headroom. Under-sizing your ESC on a platform this agile creates a reliability risk that shows up under load, not in bench tests.

For propeller selection, 10×4.5-inch carbon fiber is the tested configuration. A 10×5.0 pitch variant increases peak thrust by approximately 4–6% at the cost of higher current draw at cruise. We don't recommend going beyond 10.5 inches — at 900KV on 6S, tip speed starts approaching the efficiency cliff past 10.5 inches, and the motor's winding isn't optimized for that load profile. See our complete motor selection guide for prop sizing rules across the full Pi Thrust range.

3115-900KV vs 4315-600KV: Which Compact Motor Is Right?

These are Pi Thrust's two compact options, and the difference is more than just stator size.

Choose the 3115 if your platform runs 6S, your arm geometry restricts prop diameter to 10 inches, or you're building a system where motor weight directly affects endurance. On the other hand, choose the 4315 if you need more payload capacity, run 8S, and have arm geometry that accommodates 13-inch props. Read the full 7-motor comparison for a complete side-by-side across the entire Pi Thrust lineup.

Build Quality: What Separates This from Consumer-Grade 3115 Motors

The 3115-900KV shares a stator designation with consumer FPV motors, but the internal specification is meaningfully different. Specifically, three components determine long-term reliability in industrial operations.

Japanese NSK Bearings

Generic bearings develop play after 80–100 hours of operation at high RPM — a slow degradation that introduces vibration before it causes complete failure. That vibration transmits directly into the camera gimbal or sensor package, degrading image quality on missions where the motor still "works." We use NSK bearings because they maintain tolerance past 200+ flight hours under normal operating conditions. In professional deployments, that matters more than the upfront cost difference.

Aimants en arc N52H

N52H is the highest-grade standard neodymium specification with H-class thermal resistance — rated to 120°C operating temperature. Arc-shaped magnets fill more of the magnetic circuit than block alternatives, which increases flux density and torque per amp. Furthermore, we source from the same supply chain used in EV motor applications, not the general magnet distribution market where grade consistency varies batch to batch.

Fil de bobinage 220 °C

Standard winding wire carries a 155°C thermal rating. Ours carries 220 °C — the same grade used in industrial servo and traction motors. This is the thermal headroom that keeps winding insulation intact after 200+ flight cycles in hot ambient conditions, rather than degrading progressively after 50. On a platform operating through a full summer season in South Asian or Middle Eastern environments, that margin is not theoretical.

Questions fréquemment posées

What does 3115-900KV mean?

3115 describes the stator: 31mm diameter, 15mm height. 900KV means the motor spins at 900 RPM for every volt applied — at 6S (22.2V nominal), that's approximately 19,980 RPM unloaded. KV is not a power rating; it's a speed constant that determines prop matching. See our full KV rating guide for a detailed explanation.

Can I run the 3115-900KV on 8S?

We don't recommend it. At 8S (29.6V nominal), the no-load RPM approaches 26,640 — far beyond the aerodynamic efficiency range of a 10-inch propeller and significantly above the motor's rated operating envelope. Running 8S with a smaller prop (7–8 inch) is technically possible but defeats the purpose of the 3115 design entirely. For 8S platforms, the 4315-600KV is the appropriate choice.

What MTOW can a 4-motor quad achieve with four 3115-900KV motors?

Four motors generate 18,400g total static thrust. At the industry-standard 2:1 thrust-to-weight safety margin, that supports a safe MTOW of approximately 9.2 kg. In practice, a typical compact mapping quad configuration comes in at: airframe 2.5 kg + battery 1.8 kg + camera/avionics 1.2 kg = 5.5 kg operating weight, leaving 3.7 kg of additional payload capacity before reaching the 2:1 limit.

Is the 3115-900KV compatible with ArduPilot and PX4?

Yes. The motor is a standard three-phase brushless design — the flight controller stack determines compatibility, not the motor. Any ArduPilot or PX4 system paired with a 6S-rated ESC (80A+ continuous) drives the 3115-900KV without configuration changes. Standard PWM, DSHOT300, DSHOT600, and CAN bus protocols all work.

How does the 3115 compare to the 4312-380KV for inspection work?

The 4312-380KV generates more than double the peak thrust (13,000g vs 4,600g) and suits heavier platforms with 13-inch props at 8–12S. However, the 3115-900KV's smaller diameter and faster throttle response give it an advantage in tight-environment inspection — confined structures, corridor surveys, and close-range infrastructure work where the 4312's larger prop disc becomes a constraint. The right choice depends on your platform geometry and payload weight. Read the 4312-380KV review for a detailed breakdown of the larger motor.

Can Pi Thrust customize the KV or winding configuration of the 3115?

Yes — custom KV winding, shaft length, connector type, and laser-engraved logo are all available. Minimum order quantities apply for custom specifications. Contact us directly with your voltage, prop, and thrust requirements and we'll confirm what's achievable within a 7-day prototype timeline.

Spec the 3115 for Your Build

The 3115-900KV is the right motor for compact 6S platforms where arm geometry, motor weight, and throttle responsiveness matter as much as raw thrust. Not sure it's the right fit for your airframe? Share your MTOW target, battery configuration, and mission profile — we'll confirm the correct motor and prop pairing before you order.

Get in Touch

• Courriel : info@pithrust.com
• WhatsApp : +86-198-7242-8734
• Site web : pithrust.com

Also see our guide de sélection des moteurs de drone for a structured approach to matching motor, prop, and voltage across all seven Pi Thrust models.