Ever since miniquads have burst on the radio control and FPV scene, there have been a ton of talented designers getting creative making lightweight and sturdy frames for racing and acrobatics.
While there are far too many types of frames to list them all in a single post, most of those frames can be split into two types: unibody frame and frames with detachable arms. Let’s examine the pros and cons of each type of frame.
Unibody frames werer first made popular by the highly successful QAV250 and current highly regarded unibody frames include the QAV210, QAVX210, and the RMRC Goby 210.
Unibody frames have a single bottom plate with all four arms a part of the whole plate. The plate varies in thickness, from 2.5mm on smaller 3 inch frames to 4 and even 5 mm on larger 5 inch and 6 inch frames.
These bottom plates are cut from a single sheet of carbon fiber and are incredibly strong. They can take a hell of a beating without cracking, and you’d have to crash pretty hard into concrete or steel to be able to do some damage.
Unibody frames are super easy to put together. They usually have no more than 3 or 4 parts – a bottom plate, a top plate, a camera plate(s), and in some newer frames like the QAVX210, a HD camera plate as well making initial assembly really straightforward.
The big disadvantage with unibody frames is that breaking a single arm means you have to replace the entire plate, and it’s a hassle worthy of an entire afternoon(or weekend if your build is very tight).
If you’re looking to build a micro, unibody frames are the only option you have. There’s no room on such a tiny build to fiddle around with arms and screws, so you’ll get a single piece of carbon fiber.
Frames with detachable arms
Frames with detachable arms include the Alien, the Shrike, the QAV-R, the ZMRX210, and the good ol’ ZMR250.
These frames are a little more fiddly to assemble, depending on the frame. For me, assembling my first ZMR250 was a huge hassle because I was trying to route the wires between the two bottom plates. Trying to manage 4 arms held in by loose screws through poorly milled holes all whilst running wires through was not a pleasant job.
The Alien and QAV-R are much simpler builds however, only requiring 3 bolts per arm to hold it to the bottom plate.
Usually the point of impact in any crash is going to be an arm, so with frames like these, you only have to replace the one arm instead of the entire bottom plate. This also works out to be cheaper – especially if your frame doesn’t have a warranty on it.
Note: Frames from Armattan, Racedayquads and TheFlynoShop are ones that I am aware of that are warrantied. Epiquad frames give you a significant discount on a new bottom plate if you manage to break one.
A secondary advantage of frames like the QAV-R and Alien is that the arms are swappable, which means you can use 4-inch propeller or 6-inch propeller arms on the same main frame just by swapping them out.
The main con of a modular design is the bottom plate is going to be weaker in these frames. The unibody frames had a solid 3 or 4 mm bottom plate, whereas these frames have only 1.5mm or 2mm bottom plates to compensate for the added weight of the bolts.
As a result, the bottom plate may be a little weaker and not as able to survive a nasty crash. It may be a pain to get a new bottom plate every time you break it.
However, as I’m seeing with my new ZMRX210, it’s actually very difficult to crash in a way that impacts the bottom plate directly. The arms are designed in such a way that they usually bear the brunt of the impact, so it may not be as big of a problem.
I think that for all their respective pros and cons, whether you choose to get a unibody frame or a detachable arm frame will boil down to personal preference and brand loyalty. Mr Steele for example swears by the Alien frame, and Charpu uses Luminier products, and both are exceptional pilots.
As a general rule of thumb, if you are building light and your quad AUW is under ~400g then a unibody will probably be better for you and will be unlikely to break. While if you building heavier with larger motors then you would be far better off with a modular design as replacing arms is fairly common and not too much hassle.
By Shabbir Nooruddin of fpvfrenzy (guest writer)