How to choose FPV Drone Frames

by Oscar

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.

FPV Drone Frame Anatomy

Here are the names of different parts of a quadcopter frame/chassis:

  • Arms
  • Top / bottom plates
  • Camera mount
  • Standoff
  • Motor mounts
Mini Quad Frame Anatomy

Mini Quad Frame Anatomy

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.

Unibody Drone Frame

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.

Frame Size

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.

Measure the size of a mini quad frame

How to measure the size of a mini quad frame

 

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.

mini quad frame sizes - propellers size

Size comparison between 6″, 5″, 4″ and 3″ mini quad frames

Here is a table showing roughly what maximum prop size different mini quad frame sizes can support:

Frame Size Prop Size
280mm+ 7″
220-250mm 6″
180-220mm 5″
150-180mm 4″
120-150mm 3″
90-120mm 2″

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.

mini quad frame arm layout: H, X, hybrid-X, Box

H Frames

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.

True-X Frames

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.

True-X and Stretch-X mini quad frame style

Deadcat

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.

Square Frames

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.

Plus Frame

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..

Unibody Design

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.

mini quad frame - unibody or replaceable/separate arms

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.

Durability

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.

Flying Style

Most frames are designed for very specific applications and flying style, usually stated in the product description, for example:

  • Freestyle
  • Racing
  • Long range
  • Cinematic

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.

Battery Mounting

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.

Other Considerations

Weight

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.

Rigidity

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.

Motor Protection

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.

Edit History

  • 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

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16 comments

josh 2nd September 2019 - 2:18 am

um I have been reading multiple websites and have understood carbon fibre to be very expensive compared to other materials, but this blog says its relatively cheap??? Confused – what is the price range for, say, a standard mini quadcopter unibody frame in carbon fibre 3K??
cheers,
Josh

Reply
Oscar 10th September 2019 - 6:23 pm

The cost should be around $15 – $30.

Reply
Achillean 16th February 2018 - 4:47 am

In the article in the battery mounting section, you mentioned “Mounting the battery on the bottom can introduce a pendulum effect, which makes control a little less precise when doing extreme maneuvers.” Can you elaborate on this further?

I am confused because a pendulum effect will not happen in the normal context because the motors do not always point upwards. Do you mean that the battery will change the aerodynamic center of pressure of the craft and cause a moment about the crafts c.g.?

Reply
JD250 17th February 2018 - 3:59 pm

Right. Strictly talking mass, vertical (or in the direction of thrust) battery position has no effect. It took me awhile to understand this too, it is a very common misconception. So common that it has its own name: “The rocket pendulum fallacy”

Reply
Quadstar drones 17th February 2018 - 6:45 pm

Actually, it will make a difference whenever you do a maneuver. Moving the way the weight is distributed (especially with something heavy like a battery) will change the center of mass. For linear movement, this won’t affect a single thing. For angular movement, this makes a big difference since an object will always rotate (neglecting aerodynamic center of pressure) around the center of mass. In other words, it will feel a lot different when you change the position of the center of mass relative to the center of thrust. Best practice is to keep the center of mass and center of thrust as close as possible.

Reply
Oscar 6th March 2018 - 5:15 pm

I am referring to the COG becomes further away from the COT (centre of thrust), I talk a bit more about battery position in this article.

Reply
Tim 5th September 2017 - 3:38 pm

Hi Oscar,

have you ever seen/reviewed the HMB frames from MultiRC? The HMB series are made of durable plastic. I still have my HMB-235, which is being abused since 2015, and still holds well, I can’t imagine any carbon frame to be as strong…

Reply
Dey 7th July 2017 - 9:19 pm

About avoiding clones … HAH! They are as good as the originals in terms of durability maybe the finish is not as good but definitely paying for a overpriced as fuck frame is not very clever, not to mention that 80% of people in the hobby cannot afford spending 140$ in an alien so decide to go for a 20/30$ one.
If it wasn’t because chinese companies are inside the game, ImpulseRc and friends would keep stealing people “because there wouldn’t be any other option”, something similar to what has been happening with fatshark.

Reply
Mateusz 11th January 2018 - 7:58 am

It’s just an opinion or assumption that rc-aircraft CAD design and crash tests cost that much money, but the facts are that in normal life it’s called investment and it pays off very quick, after selling just a few copies. People involved in frame design and sells know that very well. There are genuine designs on the market, that sell at price slightly above production costs, and are so popular that their frames are often “in restocking” for every new design. If the product costs 3-5x the production costs to cover advertising and free give-aways to bloggers, than it’s very often not a very good frame, which hopefully disappears from the market. It’s just a wrong business model. Thanks to cloners, we do not have monopoly on frames, new designs are appearing and they get cheaper and cheaper to stay on the market, which is GOOD!

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Cocheese 4th April 2017 - 4:46 am

This guys been doing different things – came up with a “Z frame”. Being scratch built, looks like it has its weaknesses but i’m liking the concept: downanddirtydrones.com/air-drag-and-cross-sections/

Reply
Xephex 6th April 2017 - 4:36 am

Theoretically pitching the motors into a forward position and having the body angled upwards instead of angling the camera is more efficient than our current chassis form factors. Its more aerodynamic and fixes some of the current issues with camera tilt.

Reply
JD250 17th February 2018 - 3:47 pm

Name changed and hopes to do production frames: quadstardrones.com/portfolio/

Reply
Nils 1st April 2017 - 2:49 pm

Hi Oscar,

nice article, thanks. Can you identify the penultimate frame -the one with the silver brackets-. I intend to buy it :-)

Regards
Nils

Reply
Jonah 29th May 2017 - 10:55 pm

That’s the Dquad Obsession.

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Jason Tan 1st April 2017 - 1:27 am

Hey Oscar can you tell me what the name of the frame is with a curved nose that the FPV camera looks through.
It’s the second or third one down depending how you count and has an orange FPV camera and I think black and gold tiger “F” motors?
The body looks like it has been formed around a mold or jig.

Actually I’d be great to caption all the frames with their names – I know your intent was probably not to advertise frames, but I’d bet there are tons of readers wondering what this frame or that frame is.

I love the Charmeleons, however mine has little cut out “bumpers” at the end of the arms – is the plain round arm end just for the suki?

Reply
Oscar 3rd April 2017 - 6:30 pm

That’s the Sparrow R220 :)

Reply