Friday, November 13, 2015

Mini quad 101 - What is all this stuff?

First I want to express that all this is my opinion.  I'm not surveying a sample of the population to determine "the communities" view on things.

Why mini quads?
When I got into the hobby about 2 years ago multiwii boards were pretty common but the functionality was flaky.  Naze32 was new on the scene and I didn't have one or know what it was capable of.  Most people were flying larger (400mm typically measured diagonally from motor center to motor center) size multirotors using MutliWii, APM, Pixhawk, or something similar.

I'm not sure who started it but smaller (250mm size quadcopters) started hitting the scene.  These were smaller, faster, and more nimble than their larger counterparts.  These, with the addition of first person view (FPV), allowed for some pretty intense flying.  Racing and acrobatic flight pushed building these smaller, faster, and lighter.  It pushed development of flight controllers, speed controllers (escs), motors, and associated firmware.  Everyone started coming out with lightweight and strong carbon fiber frames.

As of this time I think mini quad racing is still on the rise.  Companies, and individuals, are still releasing new frames in sizes ranging from 130mm to 280mm, faster escs, different props, motors, cameras, video transmitters (vtx), and everything else that can go on a mini.  People are pushing the boundaries of what their setups can do and software engineers are constantly updating firmware to push the limits of the electronics.  There is lots of competition and advancement.  It's great!

Mini quad parts
FC (Flight controller) - I'm starting here because it's a very important part of your build.  Even though these are pretty interchangeable you'll get some advantages using one over another.  As of right now they come in only a few different varieties, and many clones.
I would say Naze32 and CC3D are the most widely used at this moment but there are lots to chose from.  Instead of getting into it I'm going to link another site. http://blog.oscarliang.net/best-flight-controller-quad-hex-copter/

Frame - There are many more varieties of frame and in my very limited experience they are all very similar.  Most are carbon fiber (varying quality) with different plate and arm thickness as well as layout.  Some are larger allowing for bigger props.  Some are made to be light, some extra durable, some specifically for a gopro and fpv, then others for line of sight acrobatics.

Motors - These  don't vary nearly as much as frame and I don't yet have experience with a lot of different choices.  I will say that cobra 2204s 2300kv are leading the charge and recommended and flown by many pros.  I've been running cobra 2204 1960kv on mine for a few months and they have seen lots of beating and still run smooth as silk.  I've only used 2204 because my experience has been with a 250 class quad.  If you're running a 150mm frame you will probably want smaller motors, but maybe not!

ESC (electronic speed controller) - Again a huge variety but current winners are kiss and littlebees.  Most of the new varieties run BLHeli with a SimonK or BLHeli bootlader.  They come in BEC and OPTO configurations.  I tend to run opto (no bec on board) and power my FC in another way.

PDB (Power distribution board) - Many different makes and models and choosing one depends on your frame of choice and power needs.  For example, my FC needs 5v and my camera gear needs 12v.  I could run anything that fits my frame and provides these options.  Some of the PDBs out there incorporate both 5v, 12v, and an on screen display (PowerOSD Pro).  That's a really nice choice for a really small or clean build.

Battery - You'll most likely be flying either 3s or 4s, though I've seen some 6s use.  I recommend going straight to 4s.  I don't recall offhand but you'll generally see a 30% increase in power when moving up one cell.  Most commonly in 250 size quads you'll see folks flying 1300mah to 1800mah.  The smaller your quad the smaller the battery.

Props - For 250 size quads you'll be using 5" or 6" with pitch varying between 3 and 4.5.  For smaller quads you'll get into 4" blades.  3 blade props produce more power but lose efficiency.  Both OscarLiang.net and RCModelReviews provide good benchmarks to follow.

Camera - Huge variety but the current leading camera is the HS1177 (PZ0420 chip).  These come in standard and the micro version.  Many of the smaller quads can only use the micro version so check your frame!

vTX (Video transmitter) - I use the Skyzone TS5823 because it's light and cheap.  I see a lot of folks using immersion as well.  For racing most people tend to stick with 200mw.

Antenna - The only real option for FPV is a circular polarized antenna.  Lookup IBCrazy and all the wonderful things he has done for the hobby!

Video recording - If you have money you'll most likely be using a go pro.  If you're like me and have less of that than a Xiaomi Yi, mobius, or runcam is just fine.

FPV Goggles - If you're racing you'll want some goggles.  There are pretty much two types to chose from: Goggles (fatshark and skyzone) or box (Quanum or Headplay).  There are others but those are the main.  I have both goggles (Fatshark Attitude V2) and a box (HobbyKing Quanum V2) so I'll be doing a thorough review in the next week.

I'll be getting into all of these in further detail with future posts.

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