There are countless FPV racing drone frame designs available, each boasting a particular advantage over its competitors. Perhaps it’s ultra-lightweight, extra strong or maybe a breeze to build. With so many diverse frames available surely there’s a ‘drone frame nirvana’ out there for everyone? Unfortunately, the answer to that question is “Well, not really…”.
For such a mechanically simple component, the frame has a huge influence on the flight characteristics of the drone, a mere inch added to the arms can wildly alter the total stability of the drone once up in the air. This is exactly why it’s so important to fly a drone frame that suits your style perfectly, and trying FPV drone frame design for yourself is an excellent way to make it so.
Before designing an FPV drone frame, you’ll have to select a Computer-aided design (CAD) environment to work in. Thankfully, CAD programs are in plentiful supply; many are entirely free to download, and your choice of software is entirely up to you. To design an FPV racing drone frame, no more than two dimensional (2D) CAD is required. However, you may choose to use a three dimensional (3D) CAD program to design more complicated frame parts such as 3D printable GoPro mounts, canopies and FPV camera mounts.
QCAD is an entirely free to download open source 2D CAD program that is designed to be exceptionally easy to use. Most people new to the CAD progress will find the QCAD environment easy to use and generously forgiving of mistakes. QCAD is the recommended design program of Armattan Productions, a subsidiary of Armattan Quads well known for their popular life-warrantied Chameleon and Rooster FPV drone frames.
Autodesk Fusion360 (2D, 3D)
Autodesk’s Fusion360 boasts a dual 2D/3D CAD environment equipped with an intuitive workflow. Users have the option to readily design and edit 3D models with the assistance of a comprehensive range of powerful tools. Fusion360 is available for a relatively modest $50 per month. A free 30-day trial is also available before committing to the product. Free Fusion360 licenses are available to both students and educators from the Autodesk website.
Basic Drawing Techniques
If you have no prior experience, drawing in a CAD environment for the first time can be particularly trying. An excellent way to quickly gain a basic knowledge of the software is to try out each of the different tools supplied by your particular choice of software. Merely sketching abstract shapes is a great way to accelerate your learning.
Perhaps one of the most useful and intuitive frame design concepts is shape matching. Notice the shapes of the various FPV drone electronic components; the flight controller is rectangular, the motors are circular. By matching the basic geometric shapes of these components, the efficiency at which your frame encloses and supports these components is maximized. As your design progresses, you’ll notice your design evolves from these basic geometries to become a sleeker and more refined series of curvatures.
Rectangles are an extremely useful pattern; they can be used to rapidly plot out a group of four points far quicker than a line tool. Rectangles can be used to define the hole spacing for components such as the flight controller, motor mount layout, and other bolt holes.
The line is primarily used to bond shapes such as circles and rectangles together. Lines are also optimal for adding detail to a design or making cutouts in a shape.
Circles are another essential geometry when it comes to FPV drone frame design. Their main application is as hole cutouts for bolts, and as motor mount templates. Circles can also assist in producing a rounded cutout
The arc is mainly reserved for use as a “clean-up” tool, to neaten the joint between a circular shape and a line. Arcs allow the designer to create flowing shapes that will improve the attractiveness and possibly strength of a frame.
The round/fillet tool acts similarly to the arc; it produces a smooth linkage between lines. The round/fillet tool is excellent for softening up sharp corners and removing possible stress risers that may occur at these locations.
Essential Criteria to Consider
Before drawing your frame up in CAD, it’s worthwhile to compile a short list of necessary frame parameters. These specifications assist you in focusing on the critical aspects of your design as you are drawing it, preventing any unfortunate errors being made during the design process. Below are some examples of criteria that should be considered when designing an FPV drone frame. (Click here to learn more about the anatomy of the drone frame)
The number of motors (You’re not just limited to the quadcopter format!)
Motor layout (This could be true, wide or stretch X, just to mention a few)
Rotorbase (The rotorbase is the diagonal distance between two motors measured in millimeters)
Supported motor sizes
Detachable arms or unibody plate
Full size or mini/microelectronics
Supported battery sizes
Top or bottom battery mounting
HD camera support
Freestyle, race or long range?
What to Avoid?
Along with these basic frame requirements, it’s worth wrapping your head around a few of the most common mistakes made by newcomers to FPV drone frame design. The ability to recognize and avoid these issues will save your money, time and patience.
Stress risers are areas in an object where stress accumulates and ultimately leads to failure. These stress risers are usually found at sharp corners in an FPV drone frame design, usually where an arm meets the main plate or at the base of a motor mount. Rounding corners sufficiently is an excellent way to eliminate stress risers and boost the durability of a frame.
This is an irritating one; it’s incredibly frustrating to realize you’ve waited months for a frame rendered useless by an off-center hole. Before sending a design out for cutting, be sure to check all mounting holes are correctly situated by overlaying the design files. Printing out the FPV drone frame design on paper and physically measuring with a ruler is a great way to avoid these sneaky mistakes.
Carbon fiber is a composite material made up of many woven carbon fiber threads sealed in an epoxy matrix. 1×1 and 2×2 carbon fiber weaves are most common in FPV, both using two groups of carbon fiber threads positioned perpendicular to each other. Carbon fibers are strongest along their length rather than width, it’s very important that the weave travels linearly along a high stress area such as an arm. If the weave is situated at fourty-five degrees, the strength of the frame can be seriously compromised.
FPV racing drone frame oriented CNC such as Armattan will usually align the weave correctly, although a generic CNC service may need some pointers when it comes to correctly cutting drone frame parts.
It’s always worthwhile to share images of your design with those in the FPV community to gain useful critique that will assist in the evolution and optimization of your FPV drone frame design. Many FPV pilots have engineering or design backgrounds and are always enthusiastic to mentor amateur drone frame designers.
With those critical points out of the way, you’re ready to start drawing your frame!
Where to start?
With no CAD experience already under your belt, designing an FPV drone frame is nothing short of an awkward endeavor. With practice, you’ll grow faster and hopefully find a workflow that fits you. To get started, a basic work order is outlined below to acquaint you with the basic drone frame design process.
Position the flight controller mounting holes by inserting an appropriately sized rectangle and dotting the mounting holes at the corners. Usually the flight controller is placed at the centre of the frame.
Next, draw up the rectangle that will act as the framework for motor layout. Remember that the rotorbase of a quadcopter is the diagonal distance between motors. If you’re using a true-X format, the side lengths of the required rectangle can be found by dividing the rotorbase distance by 1.4.
For example, calculating the side lengths of a 210mm rotorbase frame:
210 ÷ 1.4 = 150mm
With the motor layout approximated, drop in a circle at each vertice. These circles will act as templates for the motor mounts, dimension them to at least the diameter of your selected motor size. Next, insert the required motor mount geometry into the sketch. Most motor manufacturers will supply detailed drawings of their respective motor dimensions. Optionally, add in a circle at each mount to the diameter of the largest propeller size your frame will prospectively support.
Before moving to the arms, roughly outline the fuselage geometry with a rectangle or two, be sure to size this rectangle appropriately to accommodate space for the battery and any accessories.
The addition of arms is dependent on whether your design incorporates a unibody plate or singular arms. The unibody design is simplest; there’s no concern for bolt holes or arm interlocking. For a unibody frame, draw up a rectangle projecting from each motor mount to a point on the fuselage. These rectangles will act as a guide for the arm lines which connect the motor mounts to the main body. For separate arm frames; consider plotting out the armhole geometry along the main plate then sketching the arm in a different document.
The next step is to ensure your frame can correctly shelter the electronics. Remember that there are plenty of wires and electrical components demanding of secure mounting positions. The FPV camera is usually secured by a pair of vertical mounting plates or a 3D printed mount. The RX and VTX antennas; zip tied on to the plates or mounted to a 3D printed mount set between a couple of standoffs. How you choose to mount the electronics has a significant impact on the maintenance and durability of your frame, think carefully.
With the dreary frame basics out of the way, it’s time to start smoothing out those corners and breathe a little character into the design. Frame aesthetics are subjective, try experimenting with the various arc and round/fillet style tools to achieve a unique style for your frame. After smoothing up those edges, your FPV drone frame design is almost complete.
From Design to Reality
An FPV drone frame design is hardly any use stored as a file on your computer. Once your content with your design and eager to test fly it you’ll need to pick a computer numerical control (CNC) cutting service to produce your frame. There are a handful of options available to the average hobbyist after only a limited quantity of carbon fiber frame components.
- Low cost
- Years of drone frame experience
- Streamlined design quote to purchase process
- Opportunity to sell designs from their website
- Reliable customer support
- Long international shipping times (Taiwan based)
- Long processing times (Usually two weeks)
Armattan Quads founded the Armattan Productions service in 2015. Armattan Productions allows customers access to their own Taiwan based CNC cutting facility for small order items at a very competitive price. The CNC operators at Armattan Productions are also familiar with FPV drone frame manufacturing; they can be relied on to produce well-machined pieces from Armattan’s high-quality carbon fiber.
Local CNC Services
- Faster processing and shipping times than Armattan
- More expensive (Usually)
- Possibly less FPV drone frame intuition
Unfortunately, the main disadvantage of ordering from Armattan is the processing and shipping times. Most often, a month must be allowed for the arrival of goods from Armattan Productions. Use of a local CNC service can remedy this, ensuring that your design is swiftly delivered allowing for acceleration of the prototyping process.
Digging into FPV drone frame design is both an interesting and humbling experience. Designing, building and flying your frame is a great way to get familiar with the design, manufacturing and prototyping processes, with the tools and services readily available, why not try FPV drone frame design out for yourself?