Cobra Speed 5340
- Clugh Motors
- Nov 7, 2025
- 2 min read
Updated: Dec 3, 2025

I refer to this as the King Cobra. It's an ambitious project I'm developing with the aim of launching a limited series of external rotor BLDC (Brushless Direct Current) motors specifically designed for competitive speed flight. The King Cobra project stands out due to its focus on enhancing performance, efficiency, and reliability in high-speed applications, which are critical elements in the world of competitive aerodynamics. The external rotor design of these motors allows for a larger diameter rotor, which can significantly improve the thrust-to-weight ratio, making them ideal for applications where speed and agility are paramount. The unique configuration not only contributes to better cooling but also reduces the overall footprint of the motor, allowing for more compact and lightweight designs that do not compromise on power output. Join me on this journey as I meticulously rebuild and fine-tune this commercially available BLDC machine sourced from Cobra Brushless Motors. This process involves a comprehensive analysis of the existing design, where I will be evaluating the materials used, the winding configurations, and the overall assembly techniques. Each aspect will be scrutinized to ensure that we extract the maximum performance potential from the motor. Furthermore, I will be integrating advanced technologies such as optimized electronic speed controllers (ESCs) and high-performance propellers, which will work in harmony with the King Cobra motors to achieve unprecedented levels of efficiency and speed. The goal is not only to create a powerful motor but also to ensure that it operates seamlessly with the latest advancements in flight control systems. As we progress, I will share insights into the challenges faced during the development process, including the trials of prototyping, testing, and iterating on design elements. This journey will not only be about creating a product but also about pushing the boundaries of what is possible in the realm of competitive flight. The King Cobra is not just a motor; it represents a fusion of engineering excellence and innovative design, aimed at enthusiasts and professionals alike who seek to dominate the skies.



I've decided to go with Arnon7 because to me it looks even better than SURA NO20 at elevated frequencies. If a lamination is .1mm it will be one of these newer materials that the newer drone motor are made of. 1000 laminations cost me around 2.40 cents a sheet. A 1000 sheets can bring 5 king cobra cores. NO20 was approximately 3.20 cents a sheet at a 1000 sheets. You can do the math on what a order will run me for 5 cores.
.1mm is what you will find in the new Egodrift eclipse series. Vincent Offenbeck claims they are the first but that certainly isnt true because the the drone motors like the AOS supernova has had th…
It pays off when you actually pay attention to the core materials specification information! In a high pole high speed external rotor machine there is no question based on material loss specification at frequency that Arnon7 is going to significantly outperform CoFe. 🖤
I have three American laser houses I contacted for a quote on laminations. In this process of selecting electrical steel there are some things hobbyist might like to know about the core materials for high rpm high pole count machines. Firstly CoFe is not preferred for frequencies over 1.2 Khz so a Cofe 10 pole or 14 pole motor running 16,000 rpm is not at all premium for the best performance. As an example A 3225 running at 30000 rpm is about 7Khz which is well outside CoFe's intended frequency range. OOPS!!!! 😱. I sure this is why you can not find any data confirming that a Cofe core performed any better that plain thin silicon steel in the applica…
Vacoflux X1
VACOFLUX X1 - 17% CoFe for Electric Motors | VAC
Electrical Steel non-oriented
Electrical Steel: Thin Non-Oriented Grades Datasheet