The KST X15-1208 Mini Coreless Cyclic HV Servo is a high-voltage mini digital servo built for RC helicopter cyclic control and other compact RC applications that require fast response, strong holding force, and a durable metal geartrain. It delivers up to 13.5kgf.cm torque at 8.4V with a fast 0.07sec/60° transit speed at 8.4V. With a coreless DC motor, hardened steel gears, CNC aluminum alloy case, and dual ball bearings, the X15-1208 is designed for precise control in mid-size helicopter setups and demanding model applications. KST lists it for helicopters using mini servos, including rotor blade classes around 430mm-570mm, while also noting that it can be used in other RC applications when the size, torque, and speed match the installation requirements. The servo operates across a DC 6.0V-8.4V voltage range and uses a 1520us / 333Hz control signal, making it suitable for modern flybarless systems and high-voltage BEC setups when properly configured. Features High-torque mini cyclic servo - Provides up to 13.5kgf.cm torque at 8.4V for responsive RC helicopter cyclic control. Fast 0.07sec response - Reaches 0.07sec/60° at 8.4V, supporting quick control correction in aerobatic flight. HV voltage range - Supports DC 6.0V-8.4V, allowing use with common high-voltage receiver and BEC setups. Coreless DC motor - Uses a coreless motor for smooth response and precise control feel. Hardened steel gears - Built with a hardened steel gear set for durability under demanding cyclic loads. CNC aluminum alloy case - Aluminum alloy housing improves structural rigidity and heat dissipation compared with plastic-only cases. Dual ball bearings - Equipped with 2BB support for smoother output-shaft operation. 1520us / 333Hz signal - Designed for standard digital cyclic servo signal settings used by many modern FBL systems. Compact mini size - Measures 35.5 x 15.0 x 32.5mm, fitting mini-servo airframes and compact RC installations. Programmable support - Technical data lists soft start as programmable and the servo as programmable. Specifications Parameter Value Brand KST Model X15-1208 Product Type Mini coreless cyclic HV digital servo Rated Voltage DC 7.4V Voltage Range DC 6.0V-8.4V Torque at 6.0V 9.8kgf.cm Torque at 7.4V 12.0kgf.cm Torque at 8.4V 13.5kgf.cm Speed at 6.0V 0.10sec/60° Speed at 7.4V 0.08sec/60° Speed at 8.4V 0.07sec/60° Working Frequency 1520us / 333Hz Default Travel Angle ±50° / 100° total Temperature Range -10°C to +65°C Case Dimensions 35.5 x 15.0 x 32.5mm ±0.2mm Weight 40g ±10% Output Shaft 6mm 25T Case Material Aluminum alloy Motor Type Coreless DC motor Gear Set Material Hardened steel Position Sensor Potentiometer Ball Bearings 2BB Pulse Length 900-2100us Reference Documents KST X15-1208 V8.0 Technical Specification Application RC helicopter cyclic control - Suitable for cyclic servo use in compatible mid-size RC helicopter platforms. 430mm-570mm rotor-class helis - KST describes the servo as a choice for helicopters in this blade-size range requiring mini servos. 3D flight setups - Fast transit speed and high torque support responsive control in aerobatic flight configurations. Flybarless systems - The 1520us / 333Hz signal setting is suitable for many modern FBL controller configurations. Compact RC mechanisms - Useful wherever the 35.5 x 15.0 x 32.5mm mini case and torque/speed ratings fit the design. High-voltage receiver systems - Designed for 6.0V-8.4V operation when the receiver, BEC, and flight electronics are configured correctly. Precision model control - Hardened steel gears, dual bearings, and a coreless motor make it practical for control surfaces and compact mechanical linkages. Replacement or upgrade projects - Check spline, horn geometry, mounting size, travel settings, and servo direction before replacing an existing servo. Packing List Description Quantity KST X15-1208 digital servo 1 Accessory pack 1 FAQ .faq-accordion details { border-bottom: 1px solid #e6eef8; padding: 14px 0; } .faq-accordion summary { list-style: none; cursor: pointer; font-size: 16px; font-weight: 700; color: #1f2933; position: relative; padding-right: 32px; } .faq-accordion summary::-webkit-details-marker { display: none; } .faq-accordion summary::after { content: "\203A"; position: absolute; right: 4px; top: 50%; transform: translateY(-50%) rotate(90deg); color: #007fff; font-size: 28px; line-height: 1; transition: transform 0.2s ease; } .faq-accordion details[open] summary::after { transform: translateY(-50%) rotate(270deg); } .faq-accordion p { margin: 12px 0 0; color: #4b5563; line-height: 1.65; } What is the main use of the KST X15-1208 servo? It is primarily positioned as a mini cyclic HV servo for compatible RC helicopter setups, especially where fast response and high torque are required. What torque does it provide? The technical data lists 9.8kgf.cm at 6.0V, 12.0kgf.cm at 7.4V, and 13.5kgf.cm at 8.4V. How fast is the X15-1208? The listed transit speeds are 0.10sec/60° at 6.0V, 0.08sec/60° at 7.4V, and 0.07sec/60° at 8.4V. What voltage range does it support? The servo is rated for DC 6.0V-8.4V, with a rated voltage of DC 7.4V. What signal setting should be used? The technical specification lists 1520us / 333Hz. Always set your FBL controller or receiver according to the servo and flight-controller manuals. What spline does the output shaft use? The listed output shaft is 6mm 25T. Confirm horn compatibility before installation. Is this a brushless servo? No. The technical specification lists the motor type as a coreless DC motor. What is included in the package? The listed package includes 1 x X15-1208 digital servo and 1 x accessory pack. Can it be used outside RC helicopters? Yes, it can be used in other RC applications when the physical dimensions, torque, speed, spline, travel, and signal requirements match the project.
