Overview

The Futaba HPS-A703 Standard Brushless Servo PWM/S.BUS2 is a professional-grade servo designed specifically for demanding RC aircraft applications, particularly giant-scale aeroplanes where reliability, strength and precision control are paramount. This high-voltage brushless servo combines cutting-edge motor technology with robust construction to deliver the exceptional performance required by serious RC pilots and enthusiasts across the UK and beyond. Whether you're piloting a large-scale warbird, aerobatic platform or transport aircraft, the HPS-A703 offers the control authority and response speed necessary to manage oversized control surfaces with confidence.

Built by Futaba, the world-renowned leader in RC radio control systems since 1962, this servo represents the pinnacle of engineering excellence for advanced RC aircraft builds. The HPS-A703 is particularly suitable as an upgrade for users currently running older servos such as the Futaba BLS172SV or BLS177SV, offering significantly improved performance characteristics. With its brushless motor design, high-voltage capability, digital programming options and support for modern S.BUS2 control protocols, this servo is the ideal choice for RC modellers who demand the best equipment for their giant-scale aircraft projects.

If you're searching for a professional brushless RC servo in the UK or looking to upgrade your aircraft's control systems, the HPS-A703 delivers uncompromising quality and performance. The servo's combination of speed, torque and intelligent digital features makes it suitable for complex manoeuvres and sustained aerobatic flight, ensuring your aircraft responds precisely to every control input.

Key Features

• High-Performance Brushless Motor — Featuring Futaba's custom HPS brushless motor design, this servo delivers superior efficiency and lower power consumption compared to traditional brushed alternatives, allowing your LiPo batteries to last longer during extended flying sessions whilst maintaining exceptional control responsiveness.
• Exceptional Torque Output — With a maximum torque rating of 66.0 kgf/cm at 7.4V (61.0 kgf/cm at 6.6V), this servo provides the extreme control authority needed to manage large, heavily-loaded control surfaces on giant-scale aircraft without hesitation or lag, even during demanding aerobatic manoeuvres.
• Lightning-Fast Response Speed — Achieving a transit speed of just 0.12 seconds per 60 degrees at 7.4V (0.13 seconds at 6.6V), the HPS-A703 ensures your aircraft responds instantaneously to control inputs, providing the precision and immediacy demanded by competitive and recreational pilots alike.
• S.BUS2 Digital Programming — Full compatibility with S.BUS2, S.BUS and traditional PWM control protocols means the servo integrates seamlessly into both modern digital radio systems and conventional setups, offering flexibility for various RC aircraft configurations and allowing for advanced programmable functions through Futaba's software ecosystem.
• PC Programmability — Connect the servo to your PC using a Futaba CIU-2 or CIU-3 USB adapter (sold separately) to access comprehensive programming options, allowing fine-tuning of servo behaviour, travel limits, neutral points and advanced digital features tailored to your specific aircraft requirements.
• Aluminium Case Construction — The servo's upper, middle and lower case components are manufactured from lightweight yet rigid aluminium, providing excellent thermal dissipation to keep the motor cool during extended flight sessions whilst maintaining structural integrity under demanding load conditions.
• Stainless Steel Final Gear — The critical final stage gear is machined from stainless steel rather than standard brass, offering superior corrosion resistance, enhanced durability and extended service life, particularly important for aircraft exposed to moisture and environmental elements.
• Multi-Stage Metal Gear Train — All gears feature a robust metal construction utilising a sophisticated 1-3 stage gear arrangement with high-strength metal gears throughout, delivering reliable power transmission and minimising backlash for precise control feedback.
• Standard Servo Spline — The servo features a standard 25-tooth spline with 6mm diameter, ensuring universal compatibility with a vast selection of servo arms, horns and mechanical linkages available throughout the RC hobby, making replacement and customisation straightforward.
• Compact Standard Footprint — Measuring 40.5 x 21.0 x 39.4mm and weighing just 82 grams, the HPS-A703 maintains a standard servo size, allowing easy installation into conventional servo bays on most giant-scale aircraft without requiring custom mounting modifications.
• Wide Operating Voltage Range — Operating safely from 4.8V to 8.4V with rated performance at 6.0V-7.4V, the servo accommodates various battery configurations from 2S LiPo through to 2S lithium iron phosphate (LiFe) systems, providing flexibility in your power system design.
• No BEC or Dry Battery Use Required — This servo does not feature an onboard Battery Elimination Circuit (BEC) and cannot be powered by dry cell batteries, requiring a dedicated LiPo power source connected directly to the servo for safe and reliable operation.

Technical Performance

The Futaba HPS-A703 represents a significant engineering achievement in high-performance RC servo technology, combining advanced brushless motor technology with precision digital control systems. At its core sits Futaba's proprietary HPS brushless motor, engineered to deliver explosive torque output while maintaining exceptional efficiency and thermal management characteristics. The servo's performance specifications are genuinely impressive: at 7.4V (the typical voltage provided by a 2S LiPo battery pack), the HPS-A703 generates a maximum torque of 66.0 kgf/cm and completes a full 60-degree travel cycle in just 0.12 seconds. Even at the lower rated voltage of 6.6V, the servo maintains an excellent 61.0 kgf/cm of torque, demonstrating consistent performance across the recommended voltage envelope. The brushless motor design inherently provides superior power-to-weight efficiency compared to traditional brushed designs, resulting in lower current draw and extended flight times when integrated into complex RC aircraft control systems. The servo's construction utilises a sophisticated gear reduction system featuring multiple stages of metal gears, with the critical final-stage gear specifically machined from stainless steel for maximum durability and corrosion resistance — a premium specification rarely found on servos in this class. The aluminium case (upper, middle and lower sections) provides excellent rigidity whilst actively dissipating heat generated during sustained operation, ensuring the servo maintains cool operating temperatures even during extended aerobatic sequences. With a rated voltage of 6.0V to 7.4V and an operating range extending from 4.8V to 8.4V, the HPS-A703 demonstrates the robust engineering that Futaba is renowned for, allowing safe operation across a realistic working voltage window whilst still delivering peak performance characteristics within the optimal range. The servo's 82-gram weight and compact standard dimensions make it an ideal fit for giant-scale aircraft where weight distribution and control surface authority are equally critical considerations.

What's in the Box

• 1x Futaba HPS-A703 Standard Brushless Servo
• Multiple servo horns for different linkage configurations
• Mounting hardware including brackets and fasteners

What You Need to Complete

• 2S LiPo battery pack rated for 6.0V-7.4V operation (recommended)
• RC receiver compatible with PWM, S.BUS or S.BUS2 control protocol
• Servo connectors and wiring harness if not using existing servo leads
• Futaba CIU-2 or CIU-3 USB adapter if you wish to access advanced PC programming features (sold separately)
• Mechanical linkages, push-rods or cable systems appropriate to your aircraft's control architecture

Frequently Asked Questions

• Is the Futaba HPS-A703 suitable for beginners in giant-scale RC aircraft? — The HPS-A703 is specifically engineered for advanced RC pilots operating large-scale aircraft rather than beginners. The servo's high torque output and digital programmability are designed for experienced modellers managing complex control systems. However, if you're building your first giant-scale aircraft and want professional-grade equipment from the outset, this servo will serve you exceptionally well throughout your RC flying journey. Beginners transitioning from smaller aircraft to giant-scale platforms would absolutely benefit from its robust construction and reliability.
• What battery does the Futaba HPS-A703 require? — The HPS-A703 operates at a rated voltage of 6.0V to 7.4V, which is perfectly matched to a 2S LiPo battery pack (two lithium polymer cells providing approximately 7.4V fully charged, declining to around 6.0V during flight). The servo's operating voltage range extends from 4.8V to 8.4V, providing margin for battery voltage fluctuations during the flight cycle. You should never attempt to power this servo with dry cell batteries or using an onboard BEC (Battery Elimination Circuit), as the servo does not feature integrated BEC capability and requires a dedicated power source.
• Can I programme this servo using my existing Futaba radio system? — The HPS-A703 is fully compatible with S.BUS2, S.BUS and traditional PWM control protocols, ensuring seamless integration with modern Futaba radio systems featuring S.BUS2 capability. For advanced programming options beyond basic control functionality, you'll need to connect the servo to your PC using a Futaba CIU-2 or CIU-3 USB adapter (sold separately), which unlocks comprehensive digital adjustment features through Futaba's software suite. Traditional PWM operation requires no special programming equipment — simply connect the servo to your receiver and it will function immediately.
• What is the difference between the HPS-A703 and the Futaba BLS172SV or BLS177SV servos it replaces? — The HPS-A703 represents a significant generational advancement over the BLS172SV and BLS177SV predecessors. The primary improvements include the new HPS brushless motor design (delivering superior efficiency and lower power consumption), enhanced S.BUS2 support (more advanced digital control protocols), superior torque output (66.0 kgf/cm versus older specifications), faster response speed (0.12 seconds per 60 degrees at 7.4V), and premium materials throughout the construction including stainless steel final gears and robust aluminium case components. If you're currently running either of the older Futaba servos, upgrading to the HPS-A703 will provide noticeably improved control response, greater holding torque and better overall reliability.
• Is the HPS-A703 waterproof or weather-resistant? — Whilst the HPS-A703 features robust aluminium case construction and stainless steel gears offering corrosion resistance, the servo itself is not specifically rated as waterproof or submersible. The servo should be protected from direct water immersion, though the quality construction means it can withstand exposure to moisture, damp conditions and occasional rain during outdoor flying sessions. For seaplane operations or aircraft operating in extremely wet environments, additional protective measures such as servo tape or waterproof coatings should be considered.
• Can I use the HPS-A703 in both conventional PWM aircraft and modern S.BUS2 systems? — Absolutely. The HPS-A703's multi-protocol support (PWM, S.BUS and S.BUS2) means you can freely migrate the servo between aircraft running different control systems without any compatibility concerns. This flexibility is particularly valuable if you're building multiple giant-scale aircraft or upgrading existing models over time, as you're not locked into a specific control system ecosystem.
• What is the maximum current draw of this servo during operation? — Whilst the manufacturer specifications do not explicitly state maximum current draw in amperes, the brushless motor design inherently draws less current than equivalent brushed servos whilst delivering superior torque output. The servo's power consumption is optimised through the brushless architecture, resulting in more efficient energy utilisation and reduced loading on your LiPo battery system during demanding aerobatic manoeuvres.
• Does the HPS-A703 come with mounting brackets? — Yes, the servo is supplied with all necessary mounting hardware including mechanical fasteners and installation brackets, allowing straightforward integration into standard servo bays on most giant-scale aircraft. The universal 25-tooth spline means you'll have unlimited options for sourcing compatible servo arms and horns from manufacturers throughout the RC hobby industry.

Why Buy from RC Model Shop?

RC Model Shop is a trusted UK RC retailer and authorised dealer for all the brands we stock, including Traxxas, ARRMA, Losi, FTX, Hobbywing, Spektrum and more. Based in Walsall, we have a physical store where customers are welcome to come in, view products and purchase in store. Whether you are a seasoned competitor, a weekend basher, or just discovering the world of RC for the first time, our team of experienced RC enthusiasts is here to help you find the perfect setup and provide ongoing support. Order the Futaba HPS-A703 Standard Brushless Servo PWM/S.BUS2 66kg 0.12s 4.8V - 7.4V FUT05102723-3 today with confidence, knowing you are buying from an authorised retailer with genuine products, expert knowledge and a commitment to customer satisfaction. Shop online or visit us in Walsall — we look forward to helping you get the most out of your RC experience.