This tutorial provides an overview of FPV drone frames, all the things you need to know to pick the right frame for you. Every design detail of a frame has impact on performance, practicality and durability.
What Does an FPV Drone Frame Do?
The frame of an FPV drone is the main structure that holds all the components of a quadcopter, and it provides protection to your electronics inside the drone.
Here are the names of different parts of a quadcopter frame/chassis:
- Top / bottom plates
- Camera mount
- Motor mounts
The Ideal Frame
There’s no such thing as “best frame for all”, it all comes down to the application and requirements.
The perfect mini quad frame should be strong and practical while being as light weight as possible. If you want more protection, the frame would use more material thus become heavier. If you want higher degree of practicality, you’d use more accessories which adds weight. If you want to keep the weight down, then you’d have to make sacrifice to both durability and features.
We just can’t have it all, you should prioritise what’s more important.
Materials For Mini Quad Frame
An FPV drone frame can be made from any material you can possibly think of: wood, plastic, metal, or even PVC pipes, but carbon fibre remains the most popular material because of its relatively low cost and excellent physical properties:
- Light weight – a lighter racing drone means faster speed, better agility, longer flight time, and less destructive inertia in a crash
- Strength – carbon fiber is known to be relatively tough and durable
- Rigidity – CF has high stiffness to weight ratio. Frame rigidity is important for tuning and flight performance
The downsides of carbon fiber are:
- Carbon fiber is electrically conductive. If you have live wires touching the frame it could cause a short circuit and burn out components
- It can block radio frequencies, so antennas should be mounted outside of the frame for optimal signal
There could be a substantial weight and cost difference when using different metal alloy for bolts/nuts/hardware. Steel is the cheapest option but also the heaviest. Aluminium is the lightest, but also the softest and tends to bend in a crash, and strip easily when too much torque is applied. Titanium is light weight and strong but expensive.
Construction of a Mini Quad Frame
A drone frame has two main parts: the body and the arms.
The body houses and protects your electronic components including flight controller, 4in1 ESC, FPV camera, VTX etc. Typically it consists of a bottom plate, top plate and some standoffs in between to hold them together.
The arms are for installing the motors on. The shape and thickness play a huge role in the durability of the frame, because the arms tend to be the first place to break in a crash.
Quadcopter frame size (a.k.a. wheelbase) is the diagonal motor to motor distance measured in millimetres. It dictates the size of propeller you can run on it, therefore the frame size often are referred to the maximum propeller size it can support, instead of its wheelbase. For example, when people say “a five-inch frame,” it means the frame is sized for 5″ props.
As the motors are mounted on the very end of the arms, the further away they are from the centre of rotation, the larger the moment of inertia would be. It introduces a tendency to resist angular acceleration and deceleration and makes your quad feel more sluggish and less responsive. Therefore you want to use the biggest propellers a frame can support to maximize its performance. If you run 4-inch props on a 5″ frame, it would not perform as well as on a 4″ frame.
Here is a table showing roughly what maximum prop size different mini quad frame sizes can support:
|Frame Size||Prop Size|
Frame Shape / Arm Layout
The frame shape (or arm layout) is determined by how the arms are connected to the body. It might look like some of the motor layouts are similar (they are all rectangular after all) , but it has an impact on control feel and flight performance. There are some other reasons too when choosing one particular motor layout than another.
On an “H” frame, the arms sticks out from the sides of the body at the front and rear, it looks like the letter “H”. This leads to a long and roomy body section that for installing your electronics comfortably, makes it very easy to build. Most older frames used to be H frames and very bulky.
HD camera and battery can both sit on the top plate, the weight of the quad is more spread-out. For this reason, it might feel less agile than the newer X frames due to higher moment of inertia on the pitch axis.
On a “True-X” frame all the arms meet at the centre forming a shape that looks exactly like an “X”, the distance between all the motors are equal. True-X frames tend to have a more balanced performance as the motors are contributing equally.
Some argue it has little to no difference to an H frame in terms of flight characteristics, since the mass distribution is the same, while others argue there is a difference to how the thrusts are applied on the frame due to the way the arms are connected to the body (think about leverage). Also the ways vibrations are transferred to the FC through the arms are different too..
Stretch X Frames
Similar to a “true-X” frame in appearance, the “stretch X” frame moves the front and rear motors further apart from each other. The idea is to reduce air disturbance that the rear propellers get from the front propellers, and it could improve high speed handling especially in corners.
Often used in cinematic rigs (for cruising and capturing cinematic footage using a GoPro camera) as the front motors are wider apart than the rear motors, the propellers are normally not visible in the camera’s view and doesn’t ruin the beautiful shot.
A square frame, or box frame, is pretty much an enclosed X Frame. This basically creates a tougher frame that is less likely to have broken arms. However the extra material creates more drag and weight. Not the best choice for performance but definitely helps improve strength of the arms.
Instead of flying forward like an “X”, a Plus Frame flies forward like a “+” sign. There may be some benefits with regards to motor turbulence though, because the side motors on a plus frame will always be spinning in clean air. One of the downsides is the front motor and propeller can easily get in the view of the camera. It’s not common frame type apart from the fact that it looks unique and is eye-catching..
Some frames have all the arms and bottom plate cut from a single piece of carbon fiber sheet, this is often referred to as a unibody design.
A frame can be designed to have separate, replaceable arms, but it involves extra hardware such as bolts, nuts, and an extra bottom plate.
Unibody is much lighter and makes frame assembly easier, but if you break one arm, you would have to replace the whole bottom plate and move all your motors across to a different frame, it’s a lot of work. In comparison, with separate arms you can simply replace the broken arm.
As for rigidity, I generally find frames with replaceable arms stiffer than a unibody, because the arms are usually sandwiched between two bottom plates. But of course, arm stiffness depends a lot on carbon fibre width and thickness too.
Stress points: avoid arm design that involves hard angles as it’s much easier to break in a crash, curves and round cutouts are much better for strength.
Weaves direction: there are weaves in carbon fibre sheet, and the cutting direction actually makes a different to the strength. The carbon fibre plates are stronger when cut along the weaves and weaker when it’s cut at 45-degrees to the weaves.
Carbon fibre quality: Cheap frame will most likely use low quality carbon fibre and it’s probably not going to hold up well to crashes. Unfortunately, there’s no easy way to tell by just looking at pictures of the frame. The best you can do is to check out reviews and base your judgement on the frame’s price tag and the brand’s reputation.
Carbon Fibre Thickness
Thicker carbon fiber means better strength, rigidity and sturdiness, but it also gets heavier.
Durability matters most on the arms, as they take most of the strain in a crash. This makes it common to see top, centre and bottom plates cut from thinner 3mm or even 2mm CF.
Arms in 5″ frames commonly used 4mm or 5mm CF, but advancements in racing motors have made 6mm more common, to withstand the greater forces of higher speed impacts. For 5″ frame you should be looking for at least 4mm thick arms, for 3″ – 4″ you can go down to 3mm and for 2″ just 2.5mm (or even 2mm). Any thinner than this will break too easy and too flexible for good flight characteristics.
Filing Carbon Fibre Edges
If the carbon fibre in your new frame don’t come with chamfered edges, then you could consider filing those rough and sharp edges yourself. It’s not only for the better look and feel, but also for the following practical reasons:
- Sharp edges can cut through wires, LiPo straps, etc if they are rubbing against it over time
- Chamfered the edges, and then applying Cyanoacrylate glue (CA) can prevent the carbon fibre from delamination in a hard crash
In this tutorial I will show you how to prepare a carbon fibre frame by filing the edges. It’s best to do this under running water to avoid breathing in CF dust, the ultra fine particles are harmful to your lungs.
Most frames are designed for very specific applications and flying style, usually stated in the product description, for example:
- Long range
With that being said, there’s no hard rule what frame you must use for what purpose. You can totally race with a freestyle frame, or you could freestyle with a racing frame.
If you are just starting out, I would recommend a freestyle frame as they are generally easier to build thanks to the roomy body, and they are pretty strong against crashes. As you get better, you can move on to skinnier, lighter frames.
Should we put LiPo battery on top of or underneath the frame?
Here is a more in-depth discussion whether it’s better to mount your battery on top or bottom.
For my freestyle quads, I always prefer to have the battery mounted on top for 2 reasons:
- Centre of mass is closer to the level (or plane) of the propellers, where the force is generated. This reduces the moment of inertia when rotating, it also makes the quad handle corners better in my experience
- Landing on the battery repeatedly can damage it (crashing is a different matter, you never know which side will take the blunt of the impact)
Most racing frames opt for bottom mounted battery due to the lack of space on top.
The weight of a frame comes down to how it’s designed, how much material is used and what sort of hardware is used. 5″ racing frames weigh in between 50–80g on average while Freestyle frames often weigh in from 80–120g.
FPV Camera Mounting
There are 2 FPV camera sizes: micro and nano.
Make sure to check if the frame supports the camera size you are planning to use. You will also need to find out what kind of camera tilt angle you can achieve, and how easy it is to adjust. A tilt angle that is too low or too high can hugely affect your FPV experience
FC standoff spacing
Make sure the frame supports the FC and PDB you are planning to use, most commonly FC’s have a mounting pattern of 30.5mm x 30.5mm, or 20x20mm.
We have mentioned the importance of frame stiffness more than a dozen times . A well designed frame should be strong, crash resistant, yet rigid. If there is bending or warping in the arms during flight, your quad will be prone to problematic vibrations. As a result the quad can be hard to tune, and you might get jello in your FPV feed as well as the HD flight footage. If your quad suffers from vibration, the flight controller must work harder to stabilize the copter, and in extreme cases vibrations can even cause your motors to overheat.
HD Camera Mounting
If you plan to fly with an HD camera such as a GoPro or Insta360 GO2, make sure to check if the frame supports it. You might have to spend extra to get a 3D printed mount, or it might be included in the kit.
Spare Parts and Warranty
No spare parts available means buying a whole new frame when you break an arm or top plate. A few manufacturers even offer “lifetime” warranty which allows you to get free replacement parts whenever you break them. These frames normally cost a bit more to begin with, but it’s ensuring to see manufacturers show such faith in their own products.
Extra material around the motor mount could potentially protect your motors from damage in crash. but this does increase weight.
Evolution of Mini Quad Frame
Here are some of the most iconic FPV drone frame designs that offers original and unique features. If there are other frames you think I should feature here, please comment down below.
Released back in 2014, the Blackout frames were the beginning of 5inch mini quad. It was expensive even by today’s standard, and it was hardly available back then due to its popularity. Shortly after, the ZMR250 was released, which was heavily inspired by the Blackout, but it was much more affordable and easily accessible.
The Lumenier QAV frames were made popular by their sponsored pilot, Charpu. And then there was this cool looking, but very heavy Atas Defiance 265 and Robocat.
The Alien frame by ImpulseRC was another iconic frame in 2015, as it was one of the first True-X frames and endorsed by many top pilots at the time. The Armattan F series frames were also very popular in the same period.
The most popular FPV drone size settled at 5″, because it offers the best balance between power and agility. And since then “True-X” frames became the standard of 5″ frames.
Later we have frames with different camera pod designs and 3D printing started to play a bigger part in mini quad frames.
Different materials have been used in mini quad frames, such as the Ragg-E that uses super durable HDPE. On the other extreme, some frames tried to shave as much weight as possible by making skinny arms that looks like chopsticks, such as the X-foot or the QAV-ULX.
In the 2nd half of 2016, we started to see side plates structures replacing standoffs. The Armattan Armadillo and DemonRC Fury were great examples of that.
The beginning of 2017 saw the introduction of aluminium (and other metal alloys) into frame designs. These materials are often used to provide additional protection to the FPV camera and other components, they can also be anodized to add a flash of colour. The new designs create a strong structure yet looking awesome! Both of these frames, the DQuad Obsession and Armattan Chameleon have been featured in our top 5 best frames in 2017.
Should You Buy Clone To Save Money?
No doubt, there are a lot of overpriced frames out there. And cloning is a real issue in this hobby because how cheap and easy it is to copy a frame design.
If all you could afford is the clone, then by all means go get it and have fun! But please try to avoid clones whenever possible, not just for the quality, it’s about sustainability.
It takes a company months to design, test and release a frame, it doesn’t cost the cloners anything. Especially so for mini quad frames, after all they are just pieces of carbon fibre, anyone with a CNC machine can do it. Therefore frame manufacturers inevitably suffer from copying and cloning. Cloners can sell their frames at half of the price or even lower, because they didn’t invest in R&D, and they often use cheaper material.
- Mar 2017 – Article created
- Feb 2018 – Added plus configuration description and image, updated frame size image, added anatomy image, fixed various grammar errors
- May 2022 – Revised