Bashing MiniQuad

Why miniquads ?

They are very durable, very agile, handle wind quite well, and ridiculously fun!
Most importantly, they take the fear of crash out of the equation and that means that you can push the limits of your skill and not have to worry about large repair costs. That is what bashing quads are all about, going out, doing something crazy and hoping for the best, which of course leads to lots of crashes!  :)

Crash resistance

This may well be the most important quality of these copters, so let's exploit it to the maximum. Meaning, set it up in a way that you'll have to change 4 props after the worst crashes nothing more. There are a number of factors here, the most important ones are clearance and absorption of G forces. This sounds very scientific I know, let me explain:
By clearance I mean that you should set up the frame so no matter the angle of the crash the expensive components are protected or have space to move out of the way. So place stuff so the frame itself will contact the ground or other unfortunate object to get in your way before breakable stuff can. For example camera lenses should never protrude from the frame and antennas should have space to bend out of the way instead of being crumpled (yepp mushroom style covers on semi rigid coax can provide this right out of the box). Also here is where having a wide enough arm is key, because there is nothing else to protect your motors.
If you do have to put something on top of the frame, like a Mobius for example, you can always create a little rollbar for it from steel wire, like I did on the picture below. The rollbars on mine are bent from 0.8 sprint steel wire and they have protected the delicate components under them numerous times already!

You might be asking, why the hell did this guy put the VTX on top? Well this is about the second main factor, G forces, never forget that if you are hitting an immovable object at high speeds your craft will experience quite excessive G forces, it can reach into the hundreds, and it will multiply the mass of the components with the G count. Now, let's just think about the battery, it's about a 100 grams, when you hit the ground at speed, the frame will stop, but the battery will want to go onward propelled by its momentum. So it will quickly become a bludgeoning hammer, that can destroy stuff in its way. Not to mention, that it is volatile, so if something sharp stops it, it can go boom, we don't want that do we?
So as I was thinking about putting the battery on top, I have realized, that in case of a head on crash, it will hit the back of the Mobius and push it forwards, effectively pummeling it into the ground. Not to mention that having a large mass that high acts as an inverse pendulum, which has adverse effects on stability. So I have put the battery into the frame itself, as you can see I had to change one of the standoffs to a piece of steel wire to fit it in, but this way it is well protected, and it has the forward standoffs as a stop in case of a crash.
You might also be wondering where the hell did I put the control board than?, well its on the bottom of the top plate, so the battery can slide under it. I've built a protective cover for it, so it's kinda hard to make out on the picture, but it's in the middle. Also my board is actually upside down, and rotated 90 degrees, so I have optimal accessibility of all connectors. This is one of the reasons why I love the Naze32 so much, it flies exceptionally and it can do tricks like this easily :)

One last point to crash resistance, if something can fly off, it will! so for example make sure you tie your mobius to the frame and add some colored tape to it, so when it breaks the tie down you have a chance of finding it! I've also threaded two zip ties through the back vibration dampener balls and pulled them semi tight. This was required because the camera plate tended to fly away even on minor crashes, I haven't noticed any degradation of video quality because of them and they also help to angle the Mobius upwards.

You can say my copter is optimized for crashing, well it is, because I know won't go easy on it!

What kind of frame?

Originally my main criteria when choosing a frame were durability and price, well of course they are in an inverse relationship, so the task is rather to find one that is durable enough while being cheap enough.
Since then I have learned that having enough space to place your components can save you from lots of headache, and the amount of protection a frame offers for them is vitally important!

HK (Diatone) FPV 250 with cage

This frame is cheap as beans, it has ample space to put your stuff onto so you can arrange them to be well protected. The nylon X body is virtually indestructible, and wide enough at the ends to protect the motors on crash. On the other hand, the cage is made out of relatively thin pcb board, and has lots of holes in it, so it does not like hard surfaces like concrete. Also it has to be installed in the "low hang" configuration if you want to use 6 inch props. Though the legs of the copter usually take the brunt of the force on crash, generally you'll be hard pressed to damage the frame as long as you are over a grassy are instead of concrete.
In retrospect I actually liked this frame better than the ZMR one, because it offered much more space, I've also mounted the control board the same fashion as it is shown on the pictures below so inside the cage, ziptied onto the top part. The original idea behind this placement was, to maximize vibration dampening, as almost all the mass was concentrated in the cage hanged below on vibration dampeners. I've eventually found out that it did not make such a big difference in PID values so it would justify that I had to stop flying when a hard crash managed to rip the vibration dampeners, so I have replaced them with screws. Never the less, my quad remained in this slightly unconventional arrangement, which allowed me to to lay out components much easier than before.

ZMR250 CF

This is a clone of the renowned Blackout frame, that is why it's regularly called the Cloneout frame. My recommendation is to get the CF version as it supposed to be full 3k carbon. I have checked mine every way I can, and so far it seems to be really made out of carbon, the layer count is spot on, it does conduct electricity and you can pretty much draw with its machined surface. This, being a full carbon construction, is very sturdy, I don't see anything being able to damage the frame, it has long enough arms for 6 inch props and has slightly larger bling factor than the Diatone frame.
On the other hand compared to the diatone frame, it is very small when it comes to placing your stuff, well of course it has to do with the fact that I refuse to put the battery on top.
Even bigger problem, that the arms are not wide enough under the motors, I currently fly this frame with RCX 1804 motors, but I do not think that I will put my brand new multistar elites onto it as they are almost wider than the arm, which means they can easily be damaged on a crash.

Do I need a dedicated fpv camera?

Yes, no doubt about it! While flying through a Mobius or a GoPro can be ok with airplanes, it is a big no-no with these, things are happening too quickly and the ground is always close by to give you a not so friendly reminder of the laws of physics :)

Control Board

Originally I was flying with MultiWii based control boards, but before jumping onto the miniquad bandwagon I have read somewhere that they require a 32 bit controller to be flyable, so I have invested into a Naze32. Since than I've seen them fly with 8 bit controllers like KK2 so it is not a must. On the other hand, I've never regretted getting the Naze32, not for a second, its setup is a breeze, and it feels locked in right from the start. If I recall how many hours I have spent on balancing my tricopter's propellers and trying to fine tune the PIDs. Now I don't even bother with balancing my props and this little beast still flies, though it's true that an unbalanced 6 inc prop induces much less vibration than an 11 inch one :)

Flying Acro or flying Stab

While stabilized mode is very helpful for new pilots, they should be regarded as a set of training wheels. You need them for a time, but try to dispense with its use as soon as you are comfortable with flying the craft around. I urge you to do this ASAP as you will partially have to re-learn to fly in Acro, so getting lots of experience in Stab mode is pretty pointless. Also by Stab I mean a simple horizon hold, which returns the craft to level whenever you let go of the sticks, do not even think about altitude hold or fancy control schemes offered by some controllers. You want to learn to fly the craft! Not to mention, while stab can be very helpful it severely limits your ability for fine heading controls as it constantly tries to fight you and get back to level. I've found that I was unable to progress my skill as a pilot beyond a point when flying Stab, because the FC has fought me every turn. All and all while acro mode can be a handful while flying line of sight, flying fpv and zipping between obstacles it allows a much better level of control and thus more precise maneuvering, which you will need. Do not be afraid of it, just take it slow, threat it as a completely new craft!

Center of Gravity

I've heard many times, from many people that CG does not so important for a multicopter, well now I know that they have never flown in Acro mode! Setting the correct CG matters a lot! When switching to Acro, you will soon realize that you are dealing with an aircraft instead of a flying contraption that you can move in three dimensions via more or less straight lines! Bad CG will surmount to bad flying characteristics. Just to give an example if your craft pitches aggressively up when you come out of a forward dash and trying to level out, it is likely tail heavy. Of course flying Stab will negate this effect because FCs are so damn good nowadays.

Motor

With motors, the deciding factors are power and quality of course but I have come to regard CW and CCW threaded shafts as vitally important as well as they save you lots of trouble. Thankfully there are a bunch of tried out, good quality and cheap motors out there. Like the renowned SunnySky 2204 which is easier to come by nowadays, the DYS 1806, the Emax 1804 and 1806-s and the Multistar Elites which I've ordered not so long ago, so I haven't tried them yet, but they seem real good quality, both windings and bearings alike. From these only the Emax and the Multistar series has CW and CCW variants, that's why I've gone with the Elites instead of the SS2204. Of course the RCX 1804-s which I currently fly with are ok as well, but they are far less powerful than the ones mentioned here and their quality is inferior as well.

ESC

Choosing ESC-s can seem quite difficult at first, my advice is simple, go with something that is readily available, rated high enough for your copter and most importantly, can be flashed with either BlHeli or SimonK firmware. I personally like BlHeli better, as you can set it up after flashing to suit your craft exactly where SimonK is a one size fits all kind of solution. Though it does fit almost all :) As for how high the rating should be, 12-20A should be ok, you can go higher but you'll only get excess weight out of it.
Do not fall into the same trap as I did, even if the Blheli or SimonK guide says that a given ESC can be flashed via the throttle signal cable, it is only true if it has compatible bootloader onboard already, so if it was flashed in the factory with the given firmware. I've ran into this with HK Blue 12A esc, and I had to wait for the socket programming tool to arrive before I could to anything with them.

Radio frequencies?

5.8 is the obvious choice for video, as you want compact antennas over range. Circular polarization is advised, and having an antenna with a protective cover pays of real quickly, so look for the little mushrooms :)
As for control, once again size beats all, so 2.4GHz is recommended.

Antenna polarization

I was surprised first how much my range was degraded, even though I was using OpenLRS which should be good around 20km-s or so. Turns out, as the copter usually stays very close to the ground, and itself packed very tight and quite dense, it is reducing the signal strength a lot. So make sure you orient not only your Vtx antenna but the RX antennas as well, in a way to maximize their sensitivity. When orienting the antenna don't forget that most of the time the copter will be tilted forward at quite a high angle!

Pre flight / after crash chek

• loose motors
• loose, cracked, stress lined propellers
• loose adapters
• loose antennas or components
• hover test

My advice for miniquads

• Keep the craft as simple as possible, direct solder where possible, connectors add weight and new possibilities for failure
• set up the frame to keep your expensive stuff well protected, add rollcages formed of steel wire if necessary
• use motors that have CW and CCW threads on them, so your propellers will never come loose
• use ESCs with Blheli or SimonK firmware
• use and Acro Naze32 or a CC3D control board
• try to get a PPM capable RX and use that one
• waterproof your electronics as well as humanly possible
• tie anything that can fly away to the frame with a piece of fishing line
• add colored tape to all side of your Mobius or other camera, so you'll have easier time finding it on the ground
• set up a beeper so you can find the craft after a crash
• set up failsafe on both the RX and the control board itself if possible
• ALWAYS! do pre-flight check before putting on the glasses an punching it

Thanks for reading through this rather long article!

Fly safe! :)