By Bob Hammell
Having a good quadcopter frame is just as important as having good electronics, as quadcopters depend on lightweight, sturdy hulls for mounting components. There are limitless frame designs that vary in shapes, materials and dimensions. Stiffer frames result in better flight characteristics since less bending and warping can occur, meaning your quadcopter will be able to have a smooth and stable flight.
However, if a quadcopter frame is too brittle then when the inevitable crash happens then it will result in more frequent and longer repair sessions. The perfect frame should be stiff and strong but at the same time light enough to zip through the sky with no problems at all.
One of the materials that is most common for quadcopter frames is carbon fiber.
These frames are great for quadcopters because of their physical properties which makes them perfectly suited for the hobby. The only downside is that carbon fiber is known for blocking radio signals which of course is not the best option for a hobby that depends on having numerous transmissions.
With that being said, carbon fiber frames can still be used and they often are but you should just be aware that the carbon fiber blocking the transmission signals is always a possibility. Frames can also be custom built in a do it yourself fashion at home using balsa sheet or aluminum. However, the results will vary from manufactured frames specifically in terms of flight attributes and aesthetically.
The integration of power distribution circuits into the frame plates is common. Battery connections typically get soldered directly to pads that are built into the carbon fiber material and power can be tapped at additional solder points without the need for messy, extensive wiring. Even though it is by no means necessary, a clean setup is usually less likely to fail and when all said is done more satisfying, which makes distributing frames an investment worthy of your time and money.
Depending on your budget or own aspirations you could either purchase a premade quadcopter frame, buy the parts of one and assemble your own, or create yours custom in the comfort of your own home. No matter which route you decide to go down, you should always do your research so that you know exactly how to build the frame and exactly how to.
Arms of the quadcopter attach to the frame and these can also be built at home using hard plastic tubing or aluminum. However, for most hobbyists it is preferable to purchase arms that are already pre-built. These arms are relatively easy and cheap to replace so when you purchase them you should always make sure to pick up extras so you can quickly replace them when you crash.
With this being taken into account they are typically considered a pre-determined breaking point. Should you ever crash, the arms will likely be the first components to break which helps to prevent damage to expensive electronics on the frame such as the motors or flight controller. In fact you will probably want them to be a little bit brittle, specifically on a heavier quadcopter that is prone to crash.
When it comes to quadcopters, the arms also play a crucial role in the battle against vibrations which can cause various issues especially with shaky cameras. Flight controllers, which have sensitive gyroscopes and barometers also do not react well to constant shaking. Vibrate them too much with a poor setup and you could see irrational behavior, sometimes bad enough to cause you to crash your quadcopter.
Additionally, vibrations are also the dread of anyone who hopes to use a good camera on their quadcopter. The shaking can definitely ruin the footage through an artifact known as jello, and as a result you get wavy, headache inducing distortion that is formed from progressive scanning.
If the arms you are using flex too easily then they can reverberate and create harmonics that get transferred across the quadcopter. On the other side, arms that are way too brittle and stiff will pass vibrations directly on without any dampening which will result in that exact same problems. This is why it is important to find balance with the arms of a quadcopter and the frame, so that you can prevent such problems from happening. Typically you want a fine mix of brittle and flexible.
The scale of a quadcopter is frequently denoted by the horizontal width of the frame assembly which happens to include its arms. The normal measurement is taken in millimeters from motor to motor and through the center of the frame. If a model includes numbers in the title then these measurements are probably the ones they are referring to. For example, the DJI Phantom F450 is about 450 mm across in width, the F330 is 330 mm in horizontal width, so on and so forth.
Truth be told, there really isn’t a best quadcopter frame out there. Everyone has their own opinions and needs for their specific quadcopter so it is impossible for one frame to do everything. One thing that helps when picking the right frame is knowing what you will be using it for. Even if you know that you just want a quadcopter to play around with, that doesn’t mean that every quadcopter will fit your needs.
The most common quadcopter categories are aerial cinematography, sport, sport FPV, mini, and mini FPV. All of them will need a different frame, from aerial cinematography quadcopters that will need tall landing gear and be large enough to lift a high quality camera, to sport quadcopters that are very light weight, fast, and have extremely responsive control.
When you have finally picked the right quadcopter frame, it’s always a good idea to ensure that you know how you are going to mount the flight controller. This is because certain flight controller boards come with cases that allow you to use double sided sticky tape so you can mount it to any frame, however, most boards only have mounting holes.