{"id":9567,"date":"2025-11-15T14:18:46","date_gmt":"2025-11-15T14:18:46","guid":{"rendered":"https:\/\/micromotorpro.com\/?p=9567"},"modified":"2025-11-15T14:20:05","modified_gmt":"2025-11-15T14:20:05","slug":"inrunner-vs-outrunner-bldc-motor-guide","status":"publish","type":"post","link":"https:\/\/micromotorpro.com\/de\/inrunner-vs-outrunner-bldc-motor-guide\/","title":{"rendered":"Brushless Motor Inrunner vs Outrunner: Which Wins for Torque &amp; Speed?"},"content":{"rendered":"<p>Choosing the right <a href=\"https:\/\/micromotorpro.com\/de\/product-category\/dc-motor\/brushless-dc-motor\/\">Brushless DC (BLDC) motor<\/a> topology is critical. It defines your system&#8217;s performance, efficiency, and lifespan.<\/p>\n\n\n\n<p>In the BLDC world, there are two main configurations: <strong>Inrunners<\/strong> and <strong>Outrunners<\/strong>.<\/p>\n\n\n\n<p>On the surface, the difference looks purely structural. But make no mistake: this choice dictates torque, speed, heat management, and dynamic response.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><a href=\"https:\/\/micromotorpro.com\/de\/product-category\/dc-motor\/brushless-dc-motor\/\">Inrunner Brushless Motors:<\/a><\/strong> Known for high RPM and excellent cooling. They are built for speed.<\/li>\n\n\n\n<li><strong><a href=\"https:\/\/micromotorpro.com\/de\/product-category\/dc-motor\/brushless-dc-motor\/\">Outrunner Brushless Motors:<\/a><\/strong> Famous for high torque. They are the go-to for direct-drive applications like drones and electric skateboards.<\/li>\n<\/ul>\n\n\n\n<p>As a<a href=\"https:\/\/micromotorpro.com\/de\/small-gear-motor-manufacturer-tsl-motors\/\"> custom BLDC motor manufacturer,<\/a> we solve this &#8220;Inrunner vs. Outrunner&#8221; puzzle for clients every day.<\/p>\n\n\n\n<p>In this guide, we break down the physics, performance, and ideal applications for each. Let\u2019s ensure you choose the right motor from day one.<\/p>\n\n\n\n\n\n<h2 class=\"wp-block-heading\">Key Takeaways<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Rotor radius defines torque<\/strong> \u2014 Outrunners generate more torque because the electromagnetic force acts at a larger radius.<\/li>\n\n\n\n<li><strong>KV and Kt are inversely related<\/strong> \u2014 High KV motors must have low torque constants, and vice versa.<\/li>\n\n\n\n<li><strong>Inrunners have low inertia<\/strong> \u2014 This gives them fast acceleration, quick braking, and high dynamic response.<\/li>\n\n\n\n<li><strong>Outrunners have flywheel stability<\/strong> \u2014 Higher inertia enables smoother low-speed motion under fluctuating loads.<\/li>\n\n\n\n<li><strong>Thermal strategy depends on environment<\/strong> \u2014 Inrunners excel in sealed systems; outrunners rely on airflow cooling.<\/li>\n\n\n\n<li><strong>Application decides topology<\/strong> \u2014 Drones favor outrunners for direct-drive torque; EDF jets use inrunners for high RPM.<\/li>\n\n\n\n<li><strong>Gearboxes change the game<\/strong> \u2014 When you need high torque + sealed reliability, an inrunner with a planetary gearbox is the strongest solution.<\/li>\n\n\n\n<li><strong>There is no universal \u201cbest motor\u201d<\/strong> \u2014 Only the best match between motor physics and application requirements.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe title=\"Inrunner V Outrunner | Quick Tip | Motion RC\" width=\"1290\" height=\"726\" src=\"https:\/\/www.youtube.com\/embed\/0gJwB3LdOrc?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">The Fundamentals: Anatomy of Inrunners vs. Outrunners<\/h2>\n\n\n\n<p>To understand the performance, you must look at the physics. The names come from the position of the <strong>Rotor<\/strong> relative to the <strong>Stator<\/strong>.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Inrunner Brushless Motor: The High-Speed Standard<\/h4>\n\n\n\n<p>This is the &#8220;traditional&#8221; design. Externally, it looks like a <a href=\"https:\/\/micromotorpro.com\/de\/product-category\/dc-motor\/brushed-dc-motor\/\">standard brushed motor.<\/a><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized\"><img fetchpriority=\"high\" decoding=\"async\" width=\"556\" height=\"507\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/geared-bldc-motor-tsl-gw4632-bl2418-m8-inside.webp\" alt=\"geared bldc motor tsl gw4632 bl2418 m8 inside\" class=\"wp-image-9029\" style=\"width:332px;height:auto\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/geared-bldc-motor-tsl-gw4632-bl2418-m8-inside.webp 556w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/geared-bldc-motor-tsl-gw4632-bl2418-m8-inside-300x274.webp 300w\" sizes=\"(max-width: 556px) 100vw, 556px\" \/><figcaption class=\"wp-element-caption\">geared bldc motor tsl gw4632 bl2418 m8 inside<\/figcaption><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Construction:<\/strong> The Rotor spins inside the center of the motor.<\/li>\n\n\n\n<li><strong>Stator Position:<\/strong> The Stator (coils) surrounds the rotor and is fixed to the stationary outer case.<\/li>\n\n\n\n<li><strong>Key Advantage:<\/strong> The stator windings create heat. Since they touch the outer case, heat transfers easily to the outside. This design allows for easy mounting and retrofitting.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Outrunner Brushless Motor: The Torque Specialist<\/h4>\n\n\n\n<p>The Outrunner flips the script.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large is-resized\"><img decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/12-volt-dc-brushless-motor-tsl-bldc-6132-top-view-1024x682.webp\" alt=\"12 volt dc brushless motor tsl bldc 6132 top view\" class=\"wp-image-9552\" style=\"width:568px;height:auto\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/12-volt-dc-brushless-motor-tsl-bldc-6132-top-view-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/12-volt-dc-brushless-motor-tsl-bldc-6132-top-view-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/12-volt-dc-brushless-motor-tsl-bldc-6132-top-view-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/12-volt-dc-brushless-motor-tsl-bldc-6132-top-view-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/12-volt-dc-brushless-motor-tsl-bldc-6132-top-view.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">12 volt dc brushless motor tsl bldc 6132 top view<\/figcaption><\/figure>\n\n\n\n<p><strong>Construction:<\/strong> The Rotor is on the outside. It forms a spinning &#8220;bell&#8221; or cup around the center. Permanent magnets are attached to the inside wall of this spinning shell.<\/p>\n\n\n\n<p><strong>Stator Position:<\/strong> The Stator (coils) sits stationary in the very center of the motor.<\/p>\n\n\n\n<p><strong>Key Implication:<\/strong> The entire outer casing spins. You must design your mechanics to allow for this rotating shell.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Why Inrunner vs. Outrunner Topology Determines Performance<\/h4>\n\n\n\n<p>The seemingly simple difference of whether the rotor is inside or outside is actually the fundamental reason behind all performance differences between inrunner and outrunner motors. This design choice directly affects two core physical properties:<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"750\" height=\"393\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/outrunner-brushless-motor-tsl-bldc-5520-performance-curve.webp\" alt=\"outrunner brushless motor tsl bldc 5520 performance curve\" class=\"wp-image-9450\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/outrunner-brushless-motor-tsl-bldc-5520-performance-curve.webp 750w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/outrunner-brushless-motor-tsl-bldc-5520-performance-curve-300x157.webp 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" \/><figcaption class=\"wp-element-caption\">outrunner brushless motor tsl bldc 5520 performance curve<\/figcaption><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Electromagnetic force radius:<\/strong> This directly determines the motor\u2019s torque characteristics and its speed (KV) curve.<\/li>\n\n\n\n<li><strong>Location of the heat source (stator):<\/strong> This directly defines the motor\u2019s thermal path and cooling efficiency.<\/li>\n<\/ul>\n\n\n\n<p>In the following sections, we will explore how these two factors evolve into the distinct performance behaviors of the two motor types.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Performance Insights: Torque, RPM &amp; KV in Inrunner vs Outrunner Motors<\/h2>\n\n\n\n<p>Why are Outrunners high-torque and Inrunners high-speed? It isn\u2019t magic. It\u2019s physics.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Torque Mechanics: The Lever Arm<\/h4>\n\n\n\n<p>Torque (\u03c4) is rotational force. Physics defines it as Force (F) multiplied by Radius (r).<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><a href=\"https:\/\/en.wikipedia.org\/wiki\/Torque\" target=\"_blank\" rel=\"noopener\"><img loading=\"lazy\" decoding=\"async\" width=\"220\" height=\"154\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/Torque_animation.gif\" alt=\"Torque animation\" class=\"wp-image-9569\"\/><\/a><figcaption class=\"wp-element-caption\">Torque animation by <a href=\"https:\/\/en.wikipedia.org\/wiki\/Torque\" target=\"_blank\" rel=\"noopener\">wikipedia<\/a><\/figcaption><\/figure>\n\n\n\n<p>Think of opening a heavy door:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Push near the hinge (Small r):<\/strong> It is very hard.<\/li>\n\n\n\n<li><strong>Push near the handle (Large r):<\/strong> It is very easy.<\/li>\n\n\n\n<li><strong>Inrunner:<\/strong> Electromagnetic force acts on a small internal rotor. This is like pushing near the hinge.<\/li>\n\n\n\n<li><strong>Outrunner:<\/strong> Force acts on the large outer shell. The radius is much larger. This is like pushing near the handle.<\/li>\n<\/ul>\n\n\n\n<p><strong>Conclusion:<\/strong> With the same amount of force, the Outrunner generates significantly more torque naturally.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">KV &amp; Torque Constant (Kt)<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>KV Rating:<\/strong> How fast the motor spins per Volt (RPM\/Volt).<\/li>\n\n\n\n<li><strong>Torque Constant (Kt):<\/strong> How much torque is produced per Amp.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"796\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/04\/brushless-dc-electric-motor-tsl-bldc-3650-drawing-performance-curve2-1024x796.webp\" alt=\"brushless dc electric motor tsl bldc 3650 drawing performance curve2\" class=\"wp-image-6935\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/04\/brushless-dc-electric-motor-tsl-bldc-3650-drawing-performance-curve2-1024x796.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/04\/brushless-dc-electric-motor-tsl-bldc-3650-drawing-performance-curve2-1000x777.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/04\/brushless-dc-electric-motor-tsl-bldc-3650-drawing-performance-curve2-300x233.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/04\/brushless-dc-electric-motor-tsl-bldc-3650-drawing-performance-curve2-768x597.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/04\/brushless-dc-electric-motor-tsl-bldc-3650-drawing-performance-curve2.webp 1354w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">brushless dc electric motor tsl bldc 3650 drawing performance curve2<\/figcaption><\/figure>\n\n\n\n<p>These two constants are physically inversely related.A motor with a high KV value must have a low Kt value, and vice versa.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Inrunners:<\/strong> Typically High KV (3000\u20135000+). Great for speed, lower torque per Amp.<\/li>\n\n\n\n<li><strong>Outrunners:<\/strong> Typically Low KV (100\u20131500). Lower speed, but massive torque per Amp.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Debunking the &#8220;Torque Myth&#8221;<\/h4>\n\n\n\n<p>Some engineers argue that &#8220;Outrunners don&#8217;t technically have more torque&#8221; if the KV is identical. Theoretically, this is true.<\/p>\n\n\n\n<p>But in the real world, it is about <strong>efficiency<\/strong>. Outrunners are physically superior for Low KV \/ High Torque designs due to their geometry. While you <em>can<\/em> build a low KV Inrunner, it is often inefficient.<\/p>\n\n\n\n<p><strong>The Data:<\/strong> A 20mm Outrunner can produce <strong>75% more torque<\/strong> than a 20mm Inrunner.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Dynamic Response: Inertia, Acceleration &amp; Stability in Inrunner vs Outrunner Motors<\/h2>\n\n\n\n<p>How fast can the motor start and stop? This depends on <strong>Moment of Inertia<\/strong>.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Inrunner Motors: Fast Acceleration<\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430-1024x682.webp\" alt=\"12v brushless dc motor tsl bldc 2430\" class=\"wp-image-8784\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">12v brushless dc motor tsl bldc 2430<\/figcaption><\/figure>\n\n\n\n<p><strong>Physical Principle:<\/strong><br>Rotational inertia (the resistance to changes in rotational motion) depends on mass and its distance from the axis of rotation, and is approximately expressed as:<strong>I\u223cmr<\/strong><\/p>\n\n\n\n<p><strong>Inrunner Design:<\/strong><br>The rotor\u2019s mass is concentrated near the center \u2014 with a small radius (r) and low overall mass (m).<\/p>\n\n\n\n<p><strong>Result:<\/strong><br>Very low rotational inertia.<\/p>\n\n\n\n<p><strong>Performance Advantage:<\/strong><br>This enables fast acceleration response \u2014 the motor can start, stop, or reverse direction extremely quickly, making it ideal for high-dynamic applications such as robotic joints or high-speed control systems.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Outrunner Motors: High Inertia for Smooth Operation<\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/brushless-trolling-motor-bldc-4825-1024x682.webp\" alt=\"brushless trolling motor bldc 4825\" class=\"wp-image-9540\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/brushless-trolling-motor-bldc-4825-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/brushless-trolling-motor-bldc-4825-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/brushless-trolling-motor-bldc-4825-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/brushless-trolling-motor-bldc-4825-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/brushless-trolling-motor-bldc-4825.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">brushless trolling motor bldc 4825<\/figcaption><\/figure>\n\n\n\n<p><strong>Physical Principle:<\/strong><br>In an outrunner, the entire outer \u201cbell\u201d rotates \u2014 containing all the magnets and the metal housing. This means the mass (mmm) is large, and it is distributed at the <strong>maximum radius<\/strong> (rrr).<\/p>\n\n\n\n<p><strong>Result:<\/strong><br>Very high rotational inertia.<\/p>\n\n\n\n<p><strong>Performance Drawback:<\/strong><br>Slower response and acceleration \u2014 it requires more energy to start and stop.<\/p>\n\n\n\n<p><strong>Performance Advantage (Trade-off):<\/strong><br>The high inertia creates a <strong>flywheel effect<\/strong>, resulting in smoother and more stable rotation at low speeds, especially under load variation.<br>This is highly beneficial for applications requiring <strong>smooth, jitter-free motion<\/strong>, such as camera gimbals or low-speed RC crawlers.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Advanced Topic: How Load Inertia Influences Inrunner vs. Outrunner<\/h4>\n\n\n\n<p>A common engineering question is: <strong>To what extent does motor inertia affect the entire system?<\/strong><\/p>\n\n\n\n<p>In some applications\u2014such as driving a large drone propeller\u2014the <strong>load\u2019s rotational inertia<\/strong> (the propeller) can be <strong>orders of magnitude higher<\/strong> than the rotor inertia of the motor itself.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-drone-motor-tsl-bldc-3320-1024x682.webp\" alt=\"bldc drone motor tsl bldc 3320\" class=\"wp-image-9514\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-drone-motor-tsl-bldc-3320-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-drone-motor-tsl-bldc-3320-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-drone-motor-tsl-bldc-3320-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-drone-motor-tsl-bldc-3320-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-drone-motor-tsl-bldc-3320.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">bldc drone motor tsl bldc 3320<\/figcaption><\/figure>\n\n\n\n<p>In this case (<strong>high-inertia load<\/strong>), the inertia difference between an inrunner and an outrunner becomes almost negligible in terms of overall system acceleration time.<\/p>\n\n\n\n<p>At that point, the <strong>only factor determining acceleration is the motor\u2019s torque (Kt)<\/strong>.<\/p>\n\n\n\n<p>Therefore, the difference in internal rotor inertia <strong>only becomes truly important in low-inertia load applications<\/strong>, such as small robotic joints or high-speed spindles.<\/p>\n\n\n\n<p>This is a <strong>critical nuance<\/strong> that must be considered when designing a motion system.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Thermal Management: Ensuring Longevity in Inrunner vs Outrunner Motors<\/h2>\n\n\n\n<p>One of the most misunderstood aspects in motor design is <strong>thermal behavior<\/strong>.<br>There are completely opposite claims about \u201cwhich cools better, inrunner or outrunner?\u201d<\/p>\n\n\n\n<p>The key to solving this <strong>cooling paradox<\/strong> lies in understanding two different heat transfer mechanisms:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Conduction cooling<\/strong><\/li>\n\n\n\n<li><strong>Convection cooling<\/strong><\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Heat Source Focus: Why the Stator Matters in Brushless Motors<\/h4>\n\n\n\n<p>In both motor topologies, the <strong>primary heat source is the stator windings<\/strong>, due to resistive losses (<strong> I\u00b2 \u00d7 R<\/strong>).<\/p>\n\n\n\n<p>If this heat cannot be removed efficiently, the motor overheats, and in extreme cases, the magnets in the rotor may permanently demagnetize.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Inrunner Brushless Motor: Conduction cooling&amp; Sealed Design<\/h4>\n\n\n\n<p><strong>Cooling Mechanism:<\/strong><br>In an inrunner, the heat source (stator) sits at the <strong>outer layer<\/strong>, directly touching the static motor housing.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/05\/36mm-micro-brushless-motor-tsl-bldc-3625-1024x682.webp\" alt=\"36mm micro brushless motor tsl bldc 3625\" class=\"wp-image-7527\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/05\/36mm-micro-brushless-motor-tsl-bldc-3625-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/05\/36mm-micro-brushless-motor-tsl-bldc-3625-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/05\/36mm-micro-brushless-motor-tsl-bldc-3625-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/05\/36mm-micro-brushless-motor-tsl-bldc-3625-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/05\/36mm-micro-brushless-motor-tsl-bldc-3625.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">36mm micro brushless motor tsl bldc 3625<\/figcaption><\/figure>\n\n\n\n<p><strong>Benefit 1 \u2014 Conduction Cooling<\/strong><br>This creates a <strong>short and efficient thermal path<\/strong>.<br>Heat can easily conduct through the housing, then dissipate into:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Ambient air,<\/li>\n\n\n\n<li>A metal chassis,<\/li>\n\n\n\n<li>A heatsink,<\/li>\n\n\n\n<li>Or even a water-cooling jacket.<\/li>\n<\/ul>\n\n\n\n<p><strong>Benefit 2 \u2014 Ruggedness<\/strong><br>Because the outer shell does not rotate, the motor can be <strong>fully sealed<\/strong>.<\/p>\n\n\n\n<p><strong>Result:<\/strong><br>Inrunners can achieve <strong>very high IP ratings (e.g., IP68)<\/strong>, making them ideal for harsh environments such as:Dust\uff0cMud\uff0cUnderwater operation\uff0cIndustrial outdoor robotics<\/p>\n\n\n\n<p><strong>Typical Applications:<\/strong><br>Industrial automation, marine equipment, sealed actuators.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Outrunner Brushless Motor: Convection Cooling &amp; Open-Air Design<\/h4>\n\n\n\n<p><strong>Cooling Mechanism:<\/strong><br>In an outrunner, the stator is <strong>isolated at the center<\/strong>, surrounded by the rotating outer shell.<br>This creates a <strong>poor conduction path<\/strong> \u2014 heat gets trapped inside.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-fpv-drone-motor-tsl-bldc-3320-1024x682.webp\" alt=\"bldc fpv drone motor tsl bldc 3320\" class=\"wp-image-9513\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-fpv-drone-motor-tsl-bldc-3320-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-fpv-drone-motor-tsl-bldc-3320-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-fpv-drone-motor-tsl-bldc-3320-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-fpv-drone-motor-tsl-bldc-3320-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/bldc-fpv-drone-motor-tsl-bldc-3320.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">bldc fpv drone motor tsl bldc 3320<\/figcaption><\/figure>\n\n\n\n<p><strong>Engineering Solution:<\/strong><br>Outrunners must use <strong>open-air convection cooling<\/strong>.<br>The rotating bell is often shaped like a fan, pulling cool air in and pushing hot air out.<\/p>\n\n\n\n<p><strong>Result:<\/strong><br>Outrunners can dissipate heat <em>very effectively<\/em> \u2014 <strong>but only if they operate in open airflow<\/strong>, such as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Multirotor drones (propeller airflow provides forced cooling)<\/li>\n<\/ul>\n\n\n\n<p><strong>Limitation:<\/strong><br>Not suitable for sealed housings<br>Highly exposed to:Dust\uff0cWater\uff0cDebris<\/p>\n\n\n\n<p>This reduces lifetime and ruggedness.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Thermal Takeaways: Choosing Inrunner vs Outrunner for Your Environment<\/h4>\n\n\n\n<p>In summary, the choice of cooling is not about <strong>\u201cwhich is better?\u201d<\/strong>, but rather <strong>\u201cwhat is my operating environment?\u201d<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Choose an inrunner<\/strong>: If the environment is <strong>sealed, dirty, or wet<\/strong>, or if heat needs to be conducted to a chassis or water-cooling system.<\/li>\n\n\n\n<li><strong>Choose an outrunner<\/strong>: If the environment is <strong>open<\/strong>, and the motor can rely on its <strong>rotation or external airflow<\/strong> for convection cooling.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Inrunner vs Outrunner: Quick &amp; Detailed Performance Comparison<\/h2>\n\n\n\n<h5 class=\"wp-block-heading has-text-align-center\">Table 1 \u2014 Quick Specification Overview<\/h5>\n\n\n\n<div class=\"wpdt-c row wpDataTableContainerSimpleTable wpDataTables wpDataTablesWrapper\"\n    >\n        <table id=\"wpdtSimpleTable-664\"\n           style=\"border-collapse:collapse;                   border-spacing:0px;\"\n           class=\"wpdtSimpleTable wpDataTable\"\n           data-column=\"3\"\n           data-rows=\"7\"\n           data-wpid=\"664\"\n           data-responsive=\"0\"\n           data-has-header=\"0\">\n\n                    <tbody>        <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell wpdt-bold wpdt-tc-FFFFFF wpdt-bc-6495ED\"\n                                            data-cell-id=\"A1\"\n                    data-col-index=\"0\"\n                    data-row-index=\"0\"\n                    style=\" width:33.333333333333%;                    padding:10px;                    \"\n                    >\n                                        Feature                    <\/td>\n                                                <td class=\"wpdt-cell wpdt-bold wpdt-tc-FFFFFF wpdt-bc-6495ED\"\n                                            data-cell-id=\"B1\"\n                    data-col-index=\"1\"\n                    data-row-index=\"0\"\n                    style=\" width:33.333333333333%;                    padding:10px;                    \"\n                    >\n                                        Inrunner                    <\/td>\n                                                <td class=\"wpdt-cell wpdt-bold wpdt-tc-FFFFFF wpdt-bc-6495ED\"\n                                            data-cell-id=\"C1\"\n                    data-col-index=\"2\"\n                    data-row-index=\"0\"\n                    style=\" width:33.333333333333%;                    padding:10px;                    \"\n                    >\n                                        Outrunner                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A2\"\n                    data-col-index=\"0\"\n                    data-row-index=\"1\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Form Factor                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B2\"\n                    data-col-index=\"1\"\n                    data-row-index=\"1\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Slim, small diameter                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C2\"\n                    data-col-index=\"2\"\n                    data-row-index=\"1\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Large diameter, flat                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A3\"\n                    data-col-index=\"0\"\n                    data-row-index=\"2\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Torque                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B3\"\n                    data-col-index=\"1\"\n                    data-row-index=\"2\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Lower                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C3\"\n                    data-col-index=\"2\"\n                    data-row-index=\"2\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Higher                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A4\"\n                    data-col-index=\"0\"\n                    data-row-index=\"3\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        RPM                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B4\"\n                    data-col-index=\"1\"\n                    data-row-index=\"3\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Very high (high KV)                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C4\"\n                    data-col-index=\"2\"\n                    data-row-index=\"3\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Lower (low KV)                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A5\"\n                    data-col-index=\"0\"\n                    data-row-index=\"4\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Inertia                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B5\"\n                    data-col-index=\"1\"\n                    data-row-index=\"4\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Low \u2192 Fast acceleration                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C5\"\n                    data-col-index=\"2\"\n                    data-row-index=\"4\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        High \u2192 Smooth rotation                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A6\"\n                    data-col-index=\"0\"\n                    data-row-index=\"5\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Cooling                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B6\"\n                    data-col-index=\"1\"\n                    data-row-index=\"5\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Conduction (sealable)                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C6\"\n                    data-col-index=\"2\"\n                    data-row-index=\"5\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Convection (requires airflow)                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A7\"\n                    data-col-index=\"0\"\n                    data-row-index=\"6\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Environmental Ruggedness                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B7\"\n                    data-col-index=\"1\"\n                    data-row-index=\"6\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        High (IP-rated possible)                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C7\"\n                    data-col-index=\"2\"\n                    data-row-index=\"6\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Low (open design)                    <\/td>\n                                        <\/tr>\n                    <\/table>\n<\/div><style id='wpdt-custom-style-664'>\n.wpdt-tc-FFFFFF { color: #FFFFFF !important;}\n.wpdt-bc-6495ED { background-color: #6495ED !important;}\n<\/style>\n\n\n\n\n<h5 class=\"wp-block-heading has-text-align-center\">Table 2 \u2014 Engineer-Level Technical Comparison<\/h5>\n\n\n\n<div class=\"wpdt-c row wpDataTableContainerSimpleTable wpDataTables wpDataTablesWrapper\"\n    >\n        <table id=\"wpdtSimpleTable-665\"\n           style=\"border-collapse:collapse;                   border-spacing:0px;\"\n           class=\"wpdtSimpleTable wpDataTable\"\n           data-column=\"3\"\n           data-rows=\"9\"\n           data-wpid=\"665\"\n           data-responsive=\"0\"\n           data-has-header=\"0\">\n\n                    <tbody>        <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A1\"\n                    data-col-index=\"0\"\n                    data-row-index=\"0\"\n                    style=\" width:33.333333333333%;                    padding:10px;                    \"\n                    >\n                                        Technical Aspect                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B1\"\n                    data-col-index=\"1\"\n                    data-row-index=\"0\"\n                    style=\" width:33.333333333333%;                    padding:10px;                    \"\n                    >\n                                        Internal Rotor (Inrunner)                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C1\"\n                    data-col-index=\"2\"\n                    data-row-index=\"0\"\n                    style=\" width:33.333333333333%;                    padding:10px;                    \"\n                    >\n                                        External Rotor (Outrunner)                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A2\"\n                    data-col-index=\"0\"\n                    data-row-index=\"1\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Rotor Location                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B2\"\n                    data-col-index=\"1\"\n                    data-row-index=\"1\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Inside                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C2\"\n                    data-col-index=\"2\"\n                    data-row-index=\"1\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Outside bell                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A3\"\n                    data-col-index=\"0\"\n                    data-row-index=\"2\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Stator Location                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B3\"\n                    data-col-index=\"1\"\n                    data-row-index=\"2\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Outer case                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C3\"\n                    data-col-index=\"2\"\n                    data-row-index=\"2\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Center shaft                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A4\"\n                    data-col-index=\"0\"\n                    data-row-index=\"3\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Heat Source Path                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B4\"\n                    data-col-index=\"1\"\n                    data-row-index=\"3\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Direct conduction                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C4\"\n                    data-col-index=\"2\"\n                    data-row-index=\"3\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Convection only                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A5\"\n                    data-col-index=\"0\"\n                    data-row-index=\"4\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Typical IP Rating                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B5\"\n                    data-col-index=\"1\"\n                    data-row-index=\"4\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        High (fully sealable)                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C5\"\n                    data-col-index=\"2\"\n                    data-row-index=\"4\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Low (vented)                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A6\"\n                    data-col-index=\"0\"\n                    data-row-index=\"5\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Inertia Source                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B6\"\n                    data-col-index=\"1\"\n                    data-row-index=\"5\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Small center rotor                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C6\"\n                    data-col-index=\"2\"\n                    data-row-index=\"5\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Heavy external rotor                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A7\"\n                    data-col-index=\"0\"\n                    data-row-index=\"6\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Dynamic Response                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B7\"\n                    data-col-index=\"1\"\n                    data-row-index=\"6\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Very fast                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C7\"\n                    data-col-index=\"2\"\n                    data-row-index=\"6\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Slower                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row even\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A8\"\n                    data-col-index=\"0\"\n                    data-row-index=\"7\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Low-Speed Smoothness                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B8\"\n                    data-col-index=\"1\"\n                    data-row-index=\"7\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Lower                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C8\"\n                    data-col-index=\"2\"\n                    data-row-index=\"7\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Excellent                    <\/td>\n                                        <\/tr>\n                            <tr class=\"wpdt-cell-row odd\" >\n                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"A9\"\n                    data-col-index=\"0\"\n                    data-row-index=\"8\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        System Complexity                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"B9\"\n                    data-col-index=\"1\"\n                    data-row-index=\"8\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Often requires gearbox                    <\/td>\n                                                <td class=\"wpdt-cell\"\n                                            data-cell-id=\"C9\"\n                    data-col-index=\"2\"\n                    data-row-index=\"8\"\n                    style=\"                    padding:10px;                    \"\n                    >\n                                        Direct-drive compatible                    <\/td>\n                                        <\/tr>\n                    <\/table>\n<\/div><style id='wpdt-custom-style-665'>\n<\/style>\n\n\n\n\n<h2 class=\"wp-block-heading\">Motor Selection Guide: When to Choose Inrunner vs Outrunner<\/h2>\n\n\n\n<h4 class=\"wp-block-heading\">Scenario A: Multirotor Drones (from FPV Racing to Agricultural UAVs)<\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/micromotorpro.com\/de\/bldc-3320-fpv-motor-high-torque-low-consumption\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle\/\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"767\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle-1024x767.webp\" alt=\"high torque tsl bldc 3320 breaking the fpv triangle\" class=\"wp-image-9564\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle-1024x767.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle-1000x749.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle-300x225.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle-768x576.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/high-torque-tsl-bldc-3320-breaking-the-fpv-triangle.webp 1189w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/a><figcaption class=\"wp-element-caption\">high torque tsl bldc 3320 breaking the fpv triangle<\/figcaption><\/figure>\n\n\n\n<p><strong>Recommended Topology: Outrunner<\/strong><\/p>\n\n\n\n<p><strong>Technical Rationale:<\/strong><br>Multirotor drones require <strong>high torque at relatively low RPM<\/strong> to drive <strong>large-diameter propellers<\/strong> directly. The number one priority is <strong>avoiding gearboxes<\/strong>, as they add weight, mechanical complexity, failure points, and efficiency losses.<\/p>\n\n\n\n<p>Outrunners are the ideal <strong>direct-drive<\/strong> solution because their <strong>naturally low KV and high torque output<\/strong> allow the propeller to be mounted directly onto the motor shaft.<\/p>\n\n\n\n<p>Their open-frame structure and reliance on airflow cooling are advantages here, since the propellers themselves generate continuous forced convection.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Scenario B: High-Speed RC Models (EDF \u2013 Electric Ducted Fan Jets)<\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"767\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car-1024x767.webp\" alt=\"tsl bldc 2430 for rc car\" class=\"wp-image-9571\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car-1024x767.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car-1000x749.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car-300x225.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car-768x575.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car-1536x1151.webp 1536w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/11\/tsl-bldc-2430-for-rc-car.webp 1707w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">tsl bldc 2430 for rc car<\/figcaption><\/figure>\n\n\n\n<p><strong>Recommended Topology: Inrunner<\/strong><\/p>\n\n\n\n<p><strong>Technical Rationale:<\/strong><br>EDF systems are fundamentally different from multirotors. They require <strong>extremely high rotational speeds<\/strong> (30,000 RPM and above, often 50,000+ RPM) to drive multi-blade fan rotors.<br>Torque demand is secondary to speed.<\/p>\n\n\n\n<p>This is where inrunners excel: <strong>low rotor inertia and high KV<\/strong> make them the optimal architecture.<\/p>\n\n\n\n<p>Outrunners are mechanically unsuitable at such speeds due to severe balance challenges that can lead to catastrophic mechanical failure.<br>The <strong>slender geometry<\/strong> of inrunners also allows perfect integration into the central hub of EDF turbines.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Scenario C: E-Mobility Platforms (Electric Skateboards, E-Bikes, RC Crawlers)<\/h4>\n\n\n\n<p><strong>Recommended Topology: Outrunner<\/strong><\/p>\n\n\n\n<p><strong>Technical Rationale:<\/strong><br>Like multirotors, these systems demand <strong>high starting torque and precise low-speed control<\/strong>.<\/p>\n\n\n\n<p>The inherent <strong>high-torque \/ low-KV characteristics<\/strong> of outrunners allow them to be used efficiently either in simple belt-drive systems or as <strong>direct-drive hub motors<\/strong>.<br>A comparable inrunner would require a large, heavy, and expensive gearbox.<\/p>\n\n\n\n<p>Additionally, the higher rotor inertia of outrunners produces smoother starts with less cogging.<br>Although they are more exposed to environmental debris, the torque benefits normally outweigh sealing concerns in these applications.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Scenario D: Industrial Systems (Pumps, Fans, High-Speed Spindles, Robotics)<\/h4>\n\n\n\n<p><strong>Recommended Topology: Inrunner<\/strong><\/p>\n\n\n\n<p><strong>Technical Rationale:<\/strong><br>Industrial requirements prioritize <strong>reliability, lifespan, and environmental robustness<\/strong>.<\/p>\n\n\n\n<p>Inrunners provide <strong>superior conductive heat dissipation<\/strong>, enabling them to operate continuously at high load inside <strong>fully sealed housings (high IP rating)<\/strong> \u2014 something outrunners cannot achieve due to their open structure.<\/p>\n\n\n\n<p>This sealed capability protects motors from <strong>coolant in CNC spindles<\/strong>, <strong>dust in material handling robots<\/strong>, and <strong>moisture in industrial pump applications<\/strong>.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Scenario E: Extreme Torque Applications (Heavy-Lift Drones, Premium E-Bikes)<\/h4>\n\n\n\n<p><strong>Recommended Topology: Inrunner + Gearbox<\/strong><\/p>\n\n\n\n<p><strong>Technical Rationale:<\/strong><br>When an application simultaneously requires:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Extreme output torque<\/strong>, and<\/li>\n\n\n\n<li><strong>Excellent thermal performance and full sealing<\/strong>,<br>the most robust engineering solution is an <strong>inrunner coupled with a gearbox<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p>For example, heavy cargo drones and premium e-bikes often use a <strong>high-speed inrunner (efficient and easy to cool at high RPM)<\/strong> connected to a compact <strong>planetary reduction gearbox<\/strong>.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"682\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/high-torque-brushless-electric-motor-tsl-22gp-bl2418-1024x682.webp\" alt=\"high torque brushless electric motor tsl 22gp bl2418\" class=\"wp-image-9193\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/high-torque-brushless-electric-motor-tsl-22gp-bl2418-1024x682.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/high-torque-brushless-electric-motor-tsl-22gp-bl2418-1000x666.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/high-torque-brushless-electric-motor-tsl-22gp-bl2418-300x200.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/high-torque-brushless-electric-motor-tsl-22gp-bl2418-768x512.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/10\/high-torque-brushless-electric-motor-tsl-22gp-bl2418.webp 1366w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">high torque brushless electric motor tsl 22gp bl2418<\/figcaption><\/figure>\n\n\n\n<p>Although this architecture is heavier than direct-drive outrunners, it enables <strong>massive torque multiplication<\/strong> while keeping the motor completely sealed and thermally stable.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p><strong>Choosing an Outrunner = Choosing Mechanical Simplicity.<\/strong><\/p>\n\n\n\n<p>When you need direct-drive high torque in a clean, open environment, the outrunner is the optimal choice.<br>You trade environmental sealing for mechanical simplicity, lower cost, and lower weight.<\/p>\n\n\n\n<p><strong>Choosing an Inrunner = Choosing Environmental Robustness.<\/strong><\/p>\n\n\n\n<p>When you need high reliability in harsh or enclosed environments and superior thermal management (e.g., liquid cooling or heatsink mounting), the inrunner is the right solution.<br>You accept the potential need for a gearbox to achieve high torque, in exchange for durability, sealing, and long operating life.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-a89b3969 wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/micromotorpro.com\/de\/product-category\/dc-motor\/brushless-dc-motor\/\">Choose Your Inrunner Or Outrunner Brushless Motor<\/a><\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Build the Perfect Motor with TSL MOTOR<\/h2>\n\n\n\n<p>Understanding these differences is only the first step \u2014 mastering them is what we do best at <a href=\"https:\/\/micromotorpro.com\/de\/small-gear-motor-manufacturer-tsl-motors\/\" data-type=\"link\" data-id=\"https:\/\/micromotorpro.com\/small-gear-motor-manufacturer-tsl-motors\/\"><strong>TSL MOTOR<\/strong>.<\/a><\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/tsinglin-motor-micro-dc-motor-and-gear-motor-manufacturer-1024x768.webp\" alt=\"tsinglin motor micro dc motor and gear motor manufacturer\" class=\"wp-image-8807\" srcset=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/tsinglin-motor-micro-dc-motor-and-gear-motor-manufacturer-1024x768.webp 1024w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/tsinglin-motor-micro-dc-motor-and-gear-motor-manufacturer-1000x750.webp 1000w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/tsinglin-motor-micro-dc-motor-and-gear-motor-manufacturer-300x225.webp 300w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/tsinglin-motor-micro-dc-motor-and-gear-motor-manufacturer-768x576.webp 768w, https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/tsinglin-motor-micro-dc-motor-and-gear-motor-manufacturer.webp 1440w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">tsinglin motor micro dc motor and gear motor manufacturer<\/figcaption><\/figure>\n\n\n\n<p>Picking a catalog motor is guesswork. Engineering a motor tailored to your exact application is real innovation.<br>Our application engineering team specializes in thermal modeling, magnetic flux optimization, and inertia matching to deliver the most efficient and reliable solution \u2014 whether it\u2019s a high-torque outrunner for your drone fleet or a fully sealed inrunner for your medical device.<\/p>\n\n\n\n<p>Don\u2019t let your next design become a compromise.<br><strong>Contact the <a href=\"https:\/\/micromotorpro.com\/de\/small-gear-motor-manufacturer-tsl-motors\/\">TSL MOTOR<\/a> engineering team today<\/strong> to discuss your project requirements \u2014 and let\u2019s build the perfect motor together.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-a89b3969 wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link has-text-align-center wp-element-button\" href=\"https:\/\/micromotorpro.com\/de\/contact-us-for-dc-gear-motors-customization\/\">Contact TSL MOTOR<\/a><\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">FAQ<\/h2>\n\n\n\n<h4 class=\"wp-block-heading\">Q1:Why does rotor position (inside vs. outside) change motor performance so much?<\/h4>\n\n\n\n<p>Because the rotor radius directly affects torque generation, and stator placement affects heat dissipation. These two physical factors cascade into every major performance difference between inrunners and outrunners.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Q2:Are high KV motors always low torque?<\/h4>\n\n\n\n<p>Yes. KV and Kt are physically inversely related. A motor with a high KV value must have a low Kt value, and vice versa.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Q3:Why do drones almost always use outrunners, but RC jets use inrunners?<\/h4>\n\n\n\n<p>Because drones need <strong>direct-drive high torque<\/strong>, while EDF jets need <strong>extremely high RPM<\/strong>. These are opposite requirements.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Q4:If my environment is harsh (dust \/ coolant \/ humidity), can I still use an outrunner?<\/h4>\n\n\n\n<p>Not safely. Outrunners are structurally open and cannot be fully sealed. In such cases, engineers choose <strong>inrunner + gearbox<\/strong> for torque + environmental protection.<\/p>\n\n\n<div data-block-name=\"woocommerce\/featured-category\" data-category-id=\"80\" data-edit-mode=\"false\" class=\"wc-block-featured-category alignnone has-background-dim wp-block-woocommerce-featured-category\" style=\"min-height:500px;\"><div class=\"wc-block-featured-category__wrapper\"><div class=\"background-dim__overlay\" style=\"background-color: #000000\"><\/div><img decoding=\"async\" alt=\"Brushless DC Motor\" class=\"wc-block-featured-category__background-image\" src=\"https:\/\/micromotorpro.com\/wp-content\/uploads\/2025\/09\/12v-brushless-dc-motor-tsl-bldc-2430-1024x682.webp\" style=\"object-fit: none;object-position: 50% 50%;\" \/><h2 class=\"wc-block-featured-category__title\">B\u00fcrstenloser Gleichstrommotor<\/h2><div class=\"wc-block-featured-category__description\"><p>Brushless DC motors provide a solution to meet the demands for higher energy efficiency, longer lifespan, and quieter operation. As a leading manufacturer of BLDC motors,TSL Motors has developed the smallest BLDC motor, measuring just 6mm in diameter and 2mm in thickness, designed as a\u00a0<a href=\"https:\/\/micromotorpro.com\/de\/product-category\/vibration-motor\/coin-vibration-motor\/\">flat vibration motor<\/a>.<\/p>\n<\/div><div class=\"wc-block-featured-category__inner-blocks\">\n\n<div class=\"wp-block-buttons is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-a89b3969 wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/micromotorpro.com\/de\/product-category\/dc-motor\/brushless-dc-motor\/\">Mehr lesen<\/a><\/div>\n<\/div>\n\n<\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Choosing the right Brushless DC (BLDC) motor topology is critical. It defines your system&#8217;s performance, efficiency, and lifespan. In the BLDC world, there are two main configurations: Inrunners and Outrunners. On the surface, the difference looks purely structural. But make no mistake: this choice dictates torque, speed, heat management, and dynamic response. As a custom [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":9572,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[93],"tags":[],"class_list":["post-9567","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/posts\/9567","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/comments?post=9567"}],"version-history":[{"count":3,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/posts\/9567\/revisions"}],"predecessor-version":[{"id":9574,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/posts\/9567\/revisions\/9574"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/media\/9572"}],"wp:attachment":[{"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/media?parent=9567"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/categories?post=9567"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/micromotorpro.com\/de\/wp-json\/wp\/v2\/tags?post=9567"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}