Frames¶

The frame is the main body of the drone. It houses all the components that make up the drone. Quadcopters usually have frames that are made of Carbon Fiber (smaller ones have plastic frames). These come in two main categories: lightweight compact frames designed for drone racing, and freestyle frames, which are usually slightly larger than racing frames, more durable and slightly heavier too.

Choosing the right frame for your FPV drone¶

There are a lot of things that we need to consider when selecting a frame for the drones. Let's discuss the main ones:

Propeller Size - Depending on the length of the arms of the frame, specific propeller sizes will be needed. Most common are 5" and 3" propellers, and drone frames usually support them well.
Usable Internal Space - When selecting a frame, we need to consider the space available inside the frame for mounting the components. Does the frame have the right mounting-holes? Does it come with the right amount of space for all the components we will be putting into it (FC, ESC, Camera, battery, radio, antenna, etc)
Aerodynamics - How well does the drone slice through the air? Bulky drones tend to meet with higher air resistance and will need more power to fly through the air. A thin nimble frame will cut through much easier and with lesser effort.
Strength - A strong frame will survive many crashes before it breaks apart. A lightweight frame, on the other hand would break apart a bit more easily as they don't have the strength to withstand heavy crashes or drops. However, this can be a double-edged sword - a stronger drone would be heavier, and would need more power to fly. So a balance would need to be struck between strength and weight. Frames with 4mm thick plates are pretty durable and strong (but slightly heavier too). Also, 3mm thick frames are also available but will not be quite as strong.
Additional Features - Some well designed frames come with some extra features. For example, some come with overarching support rungs that protect the camera in case of a head-on collision. Others come with capabilities to mount additional cameras like GoPros. Yet others come with power distribution boards that allow you to properly distribute power from the ESC to the motors.

We recommend beginners to go with freestyle 4mm thick 5" frames instead of thinner racing-style frames, for obvious reasons

Power Distribution Board (PDB)¶

Power Distribution Boards (or PDBs) are circuit boards that help pass power from the drone battery to the various components of the drone. While these were very popular in recent times, many modern Flight Controllers (FC) come with a PDB inbuilt into the circuit, making a separate PDB unnecessary.

These usually come with many frames, and can also be separately bought if required.

In our build, we use a Flight Controller that already has an integrated PDB, and this component is not required.

Useful tips for choosing the right freestyle frames¶

The frame houses all the components of the drone, and hence, must be carefully chosen. There are a bunch of different designs, shapes and sizes available for frames today, and here we list some good pointers that we believe, will help you make a good buying decision.

Size - Drone frames are usually categorized by their ability of housing propellers. For instance, a 5-inch drone frame is not a frame that has a dimension of 5 inches - instead, the 5 inches refers to the fact that the frame is designed to work with 5-inch propellers.
Shape - Care must be taken to ensure that the drone has a form factor that supports the components you buy. For instance, some drone frames have a small form factor, and may not have enough space to host additional components that you may have thought of for your build. Other drone frames may not be designed to host some of the components you may have in mind. For instance, we have seen that some drone frames just do not have space for a DJI Air unit, and we would have to mount it underneath (exposing the air unit and possibly opening it up for damage during an unfortunate crash) or have a custom 3D-printed mount created to support it.
Mounting holes - Most new freestyle frames come with support for the two most common form factors of the Flight Controller - ESC combo (30.5mm by 30.5mm) or (20mm by 20mm). However, there are many frames out there that support only one of these two mounting types. Hence, care must be taken to ensure that the frame supports the mounting size that the flight controller comes in.
Weight - This one is a no-brainer, but we need to have this on the list nonetheless. A drone's weight will decide it's responsiveness. A drone that is too heavy will be sluggish and may not be the best option for freestyle. Since the frame is the largest part of your drone, it's weight will play an important part in the all-up weight of your drone. Most frames designed for freestyle come in the weight range of 130g to 230g, and are built with freestyle in mind. We would recommend going for a frame that is light, but does not compromise on quality to reduce weight.
Frame Thickness - The thicker the plates that make up a frame, the better it's strength and durability. Thicker frames (4-5mm thickness for arms and 2-3mm on the rest of the plates) tend to withstand impacts better, and last a lot longer than thinner frames. Thinner frames on the other hand (2-3mm thickness throughout) are lighter and faster, but also, most susceptible to damage upon impact. We recommend going for thicker frames for the first build (say 4 to 5mm)
Material - Most modern frames are built using carbon fibre reinforced plastic (commonly referred to as Carbon Fibre frames in the community). We recommend going for frames that are built with 3K Carbon Fibre. See this post by GetFPV for a more in-depth understanding of materials used in drone frames.
Arm configuration - The way the arms are designed also makes a lot of difference in terms of maintenance costs. For instance, some frames are come with linked arms while others come with arms that are individual and separate from each other. Linked arms have better stability, but add to maintenance costs where you would end up buying 2two arms even when you just need to replace one. Individual arms are great for replacement but aren't as stable as linked arms. We recommend frames that come with individual arms.
Ease of Assembly/Replacement - Another important pointer to keep in mind would be the ease of build - how easy is it to build the frame or replace a part of the frame if damaged? Some frames are so well designed that they come with a layout that allows for easy assembly and can be quickly taken apart to replace an arm, say. However, some frames are designed without this in mind, and the pilot may have to take all the inner components apart in order to change an arm. This is not too high on the list of priorities, but if available, we recommend going for a drone that is easy to build. (Note that individual arms is a plus point when we think or ease of replacement of a frame)

Additional/Optional attachments and mounts - Most frames do not usually come with custom additional parts for mounting uncommon parts. However, frames that come with a GoPro mount for instance, save the additional hassle of having to find or 3D print one, right? Here are some uncommon but essential mounting parts that frames usually do not come with:

GoPro mount
Antenna holder (for antennas like the immortal-T or others)
GPS-Chip holder
Custom air-unit holder for DJI based drones
Motor protector mounts (protect the underside of the motor mount)
Base-plate protector
Power-cord fixed mount
Mounting adapters for 20mm/30.5mm (in case the frame does not support one of the mounting sizes)

Arm Positions - Not very important, but sometimes (depending on the field-of-view of the FPV camera and the angle at which the arms are mounted on to the frame) the propellers come into the view of the camera and can obstruct proper viewing. This is not too much of a problem, but we would recommend getting a frame that has a camera mount which avoids the propellers from getting into the line-of-sight.