Operation Reverse Twist
Bringing the drone industry together to defend against the coaxial rotor patent infringement claims by Nordic Unmanned.
Bringing the drone industry together to defend against the coaxial rotor patent infringement claims by Nordic Unmanned.
Nordic Unmanned is currently asserting a coaxial rotor patent (US Patent US8328128B2; EU Patent EP2035276B1) against several drone companies in Europe. Coaxial rotor design has existed long before these patents — and arguably, they should never have been granted at all.
CubePilot filed an Ex Parte Reexamination with the USPTO in May, citing many references, where the Spanish prior art ES2268941A1, is particularly strong.
In 2017, Cloudflare was sued by Blackbird Technologies, a non-practicing entity (NPE), asserting a patent (US6453335) on basic proxy server concepts. Instead of settling, Cloudflare launched Project Jengo — a crowdsourced campaign to uncover prior art. The result? The asserted patent was invalidated, and over 30 of Blackbird’s other patents were challenged. Cloudflare later repeated this success against Sable Networks (Sable IP), another NPE.
This approach worked because the community stood together. The drone industry can — and should — do the same.
We’re calling on drone companies, developers, and innovators to form a united front against baseless patent aggression. Together, we can protect open innovation and defend the freedom to build, create, and fly.
Yoda once said, “A Jedi uses the Force for knowledge and defense, never for attack.”
In the same spirit, CubePilot believes: “Companies should use patents for innovation and defense — never for attack.”
To protect the drone industry from Nordic Unmanned’s actions, CubePilot is launching a Patent Bounty Pool — an open initiative inviting drone innovators and companies to join forces in defending fair innovation.
The asserted patents cover coaxial rotor technology, claiming features that have existed for decades.
The patent claims describe a compact multi-rotor aircraft with at least three coaxial, counter-rotating drive units, each powered by individually speed-controlled motors. It also includes claims around redundancy, rotor protection, and autonomous flight systems.
“Coaxial rotor designs existed long before these patents. They should never have been granted.”
The most valuable submissions are both strong and relevant — credible, detailed, and directly addressing the patented invention.
The following list shows the prior art references that have been considered in Office Actions, Invalidaton Proceedings, internal research and so forth.
| Reference | Title |
|---|---|
| Book | “直升机手册 航空工业出版发行 2003 年 12 月 第1版 (book about helicopter design)” |
| Book | “世界无人机大全 航空工业出版发行 2004 年 10 月 第1版 (book about drone design)” |
| Book | “Castillo et al., Modelling and Control of Mini Flying Machines, Advances in Industrial Control, Springer” |
| DE102005010336 | Speed controlled helicopter |
| DE20120758U1 | Construction for helicopter control by changing the rotor speed and protecting the rotor against contact |
| DE202004016509 | Rotorcraft with four rotors, has distances between rotation axes of rotors so small that rotor circle areas overlap with each other |
| DE202004017173 | Four-rotor helicopter with electric drive has no reduction gearboxes between motors and rotors and motors are electronically commuted external rotor electric motors |
| DE202005004698 | Collision protection device for helicopter rotors is detachably fastened on at least three points on helicopter and split into several sub-assemblies, with at least one sub-assembly connected to another only through helicopter |
| EP0513245 | VTOL aircraft |
| ES2268941 | Lightweight Aircraft And Vertical Landing |
| FR2146918 | Fliegende Plattform — Flying Platform |
| GB617290 | Improvements in and relating to helicopters |
| Journal | 《IFAC Proceedings Volumes》2002 年07 月21 日第1 卷第35 期 — “Dynamic modelling and configuration stabilization for an x4-flyer” |
| Journal | 《博士电子期刊》2015 年08 月第8 期 — “共轴八旋翼无人飞行器姿态与航迹跟踪控制研究” |
| JP(S)5019198 | Hydraulically operated aircraft with a retractable propeller |
| JP1992060297 | Flying toy |
| JP2001039397 | Flying body having horizontal rotary wing |
| JP2002244875 | Electronic equipment programming system and programming method |
| JP2002370696 | Vertical takeoff and landing aircraft |
| JP2003072694 | Levitating body |
| JP2006056364 | Vertical take-off and landing aircraft |
| JP2006511399 | Rotor and vehicle passively stable during hovering |
| JP2007535438 | Rotor transportation means |
| KR200414580 | Toy helicopter |
| NASA’s 1966–67 technical notes | Documented the X-22A full-scale ducted-propeller configuration with four tilting ducts (VTOL configuration with coaxial, contra-rotating propellers in each shroud; described in Flight International, 23 Mar 1967, p.445) |
| US20050067527 | Rotorcraft having coaxial counter-rotating rotors which produce both vertical and horizontal thrust and method of controlled flight in all six degrees of freedom |
| US20060016930 | Sky hopper |
| US20060049304 | Quiet vertical takeoff and landing aircraft using ducted, magnetic induction air-impeller rotors |
| US20060226281 | Ducted fan vertical take-off and landing vehicle |
| US2916010 | Fishing line propeller guard |
| US3053480 | Omni-directional, vertical-lift, helicopter drone |
| US3722830 | Helicopter type vehicle |
| US4426049 | Dual propeller and engine drive system for aircraft |
| US5066254 | Boat propeller guard |
| US5115996A | VTOL aircraft |
| US5791592 | Helicopter with coaxial counter-rotating dual rotors and no tail rotor |
| US6688936 | Rotating toy with directional vector control |
| US7712701 | Unmanned aerial vehicle with electrically powered, counterrotating ducted rotors |
| Wired (June 4, 1999) | Reported Moller preparing a first hover test of the Skycar, noting its eight rotary engines (two per nacelle × four nacelles, matching the patent’s dual-fan nacelle concept) |
| WO2000040464 | Stabilizing control apparatus for robotic or remotely controlled flying platform |
| WO2005099415 | Rotary wing vehicle |
| WO2006112578 | Vertical take-off and landing aircraft |
| WO2008000203 | Aircraft |
| 特開昭5019198 (JP) | Hydraulically controlled fluidstream-driven aircraft |
| WO2002064426A1 | Ultralight coaxial rotor aircraft |
| US6450445 | Stabilizing control apparatus for robtic or remotely controlled flying platform |
| US5351913A | Coaxial transmission/center hub subassembly for a rotor assembly having ducted, coaxial counter-rotating rotors |
If you wish to contribute to the patent pool, contact CubePilot. The following shows the list of companies that are contributing to the patent pool along with their contribution amounts:
| Company Name | Contribution Amount (USD) |
|---|---|
| CubePilot | 💵 $20,000 |
| Anonymous Donor | 💰 $20,000 |