The fundamental aeromechanics for the majority of helicopters have remained unchanged since Igor Sikorsky’s VS300 first flew in 1939. The single main rotor provides lift and control, whilst the tail rotor counteracts torque, preventing the helicopter from spinning uncontrollably. Certo Aerospace has gone an alternative route, with two large, contra-rotating rotors on the same axis (“coaxial”) dispensing with the tail rotor, thereby eliminating both 15 percent energy loss and the risk of serious failures in the tail rotor system.
With a design ethos of simplicity and reliability, this coaxial approach avoids other inherent pitfalls of multi-rotor and tandem aircraft, such as rotor inefficiency, control complexity, and larger aircraft size. Certo’s CAPSTONE has a dry weight of 300kg but can lift another 300kg as fuel and payload, giving an impressive one-to-one ratio and a Maximum Take-Off Weight of 600kg.
High-Flying Efficiency Meets Dynamic Payload Performance
This exceptional performance results from the proprietary coaxial rotor head integrated with a high power-to-weight internal combustion engine using liquid fuels such as petrol and diesel. These standard fuels contain at least 20 times more energy per kilogram than the latest Lithium-Ion batteries, providing the payload, range, and endurance needed for real-world missions.
“Uncrewed coaxial helicopter designs are a rarity, making our approach generally very distinctive.” says Justin Tooth, Managing Director. “However, we think coaxial is the logical choice, all things considered. And because we have cyclic and collective swashplates on both rotors, CAPSTONE has a uniquely powerful ability to generate lift with precise airflow vectoring for control in windy conditions or operating to the decks of naval ships.”
With that working payload capacity of 300kg, CAPSTONE can transport a wide range of logistics payloads or mission packages driven by plentiful onboard electrical power. Trading payload for fuel enables lighter payloads to be carried further (up to 500km) or for longer (up to 8 hours), allowing operators to match CAPSTONE capabilities to specific mission objectives, including humanitarian assistance.
Smart Design Delivers Mission Flexibility and Reliability
The Modular Open Systems Approach (MOSA)—which encapsulates the use of modular design, modular interfaces, and conformance to open standards—underpins Certo’s scalable design. CAPSTONE can be easily reconfigured with alternative Command and Control systems (C2), BVLOS navigation, automatic take-off and landing systems, and mission equipment packages.
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If heavy drones were cars, we would be in about 1901. The first machines are starting to be available but we’re still learning what actually works
Initially utilising using Certo’s proprietary coaxial flight computer software, CAPSTONE’s inherent stability has enabled the switch to off-the-shelf government-compliant BLUE CUBE hardware and Open-Source software. This allows integration with a host of other control systems so that customers can use their preferred C2 architectures.
CAPSTONEs are built using affordable materials such as steel and fibreglass, swerving expensive alternatives like machined aluminium, titanium and carbon fibre composites which are less practicable in the field. The rugged airframe with interchangeable undercarriage systems makes CAPSTONE configurable for any mission. Options include a marinisation package, internal and external cargo carriage solutions such as underslung loads, a wide range of surveillance equipment such as EO/IR and mobile phone trackers, and military effectors.
New Era In Flight Economics
CAPSTONE’s design and manufacturing approach translates directly into reduced acquisition and operating costs. The unit price tag is expected to be less than 10 percent that of the helicopters it aims to replace, with the major benefit of significantly reduced operating costs such as fuel (down 95 percent) and personnel requirements (down 90 percent).
There is already an expanding range of applications where the economics and effectiveness of VTOL UAS is being promoted by operators, including maritime logistics for offshore energy installations, Search and Rescue, agriculture and forestry, disaster relief and casualty evacuation.
“No commercial drone currently operates at our size, largely due to the early stage of adoption of relevant airspace regulations for this class of UAS to operate beyond line of sight. But this is starting to change, and we will be at the vanguard of this new industry” explains Tooth. “If heavy drones were cars, we would be in about 1901. The first machines are starting to be available but we’re still learning what actually works. Our flight operations are currently authorised by the UK CAA under the Specific Operational Risk Assessment (SORA) framework and we envisage CAPSTONE’s first commercial and government-use operators will also use SORA as we work up the concepts of operations.”
Ready For Take-Off With Proven Performance
Thanks to promising flight test results, and steady progress by the industry regulators including CAA, EASA and FAA, Certo anticipates CAPSTONE will be operational in real-world missions in 2027.
Certo is no newcomer to aerospace innovation. It has spent over 10 years pushing the envelope of coaxial aircraft development, including the concept SkyBike and the unmanned SkyFalcon that was a key component of the Department of Defense program Unmanned Logistics Systems (Air). This tested Certo’s ability to integrate its C2 to advanced third-party US autonomy systems and most importantly helped sow the seeds of the new CAPSTONE.
Following these years of testing in both the UK and US, Certo is now taking its program to the next level. By securing access to a little-used military airfield in the UK, Certo will focus on expanding CAPSTONE’s flight envelope, demonstrating payloads of over 300kg and long-duration missions over five hours, while continuing to trial the integration of mission systems.
The newest CAPSTONE variant will have a multi-fuel engine designed to run on JP-8 and other military Heavy Fuels plus synthetic fuels and (via a simple switch selection) regular gasoline.
Market demand for heavier payloads will necessarily lead to larger VTOL drones. Tooth points out that scaling up lift capability (via bigger rotors and a bigger engine) without a huge enlargement of its “form factor” or footprint is far easier with a coaxial than any conventional or standard multi-rotor configuration.
With its sights set on military and civil applications, demonstrated in flight tests in 2026 and 2027, multiple pathways for further innovation, and stated intentions to set up in the United States, Certo is a fast-growing company, which government and industry stakeholders will continue to watch closely.
