Multirotor, multicopter and quadcopter discussion - The Drone thread

I'm currently building a tri, frame is complete and ordered some components. I'm worried after reading about the care needed over Lipo batteries about keeping it in good condition. What (if any) Lipo alarm are people using/can recommend?
 
Great thread and some great quads in here.

If I want to build up a quad over the next few months what steps should I do first?

I've seen this frame on ebay which seems reasonably priced http://www.ebay.co.uk/itm/190644781...sid=p3984.m1438.l2649&clk_rvr_id=343351806505

I have no soldering experience so is it possible to by "matched" combinations that I can just plug in together?

With regards to the tx/rx what should you be looking for?
 
You can but it's likely that it would cost you more. Personally I'd just learn to solder, it's really not that hard. Just buy a soldering iron, some flux core solder and get some wire scraps and learn to do it.

With regards to the transmitter and receiver, any 4-6 channel will do. The best thing you can do though is jump on RCGroups and read! http://www.rcgroups.com/multi-rotor-helis-659/
 
In some cases getting up to around 200% to 300% more for buying kit that is specifically paired for multirotor stuff. There is some pretty serious kit out there. The main components that you'll need to look into and understand are the following:

- Flight Controller (ranges in price and capabilities)
- Batteries (and chargers since they use special balance chargers to stop from damaging lipo batts)
- Motors
- ESCs to match the load that the motors demand and also that will deal with the signal rate coming from the flight controller)
- RX/TX
- Paired propeller sets (a quad has opposing rotating motors or counter rotating and you need the props to go with that)

I'm in Aus so it's about my bed time, I will write something a bit more comprehensive tomorrow and link you to some useful info.

It's still pretty niche stuff so as a result the learning curve is a little steep and it does require a little self teaching along the way but I'm happy to point you in the right direction.
 
Just seen that this has finally been bumped :).
You will have to learn to solder as you need an awful lot of bullet connectors. I think I can count 20 lol.

al4x said:
Wish I had the ability to make this! Looks pretty good!
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You do :)


Jamie said:
I'm currently building a tri, frame is complete and ordered some components. I'm worried after reading about the care needed over Lipo batteries about keeping it in good condition. What (if any) Lipo alarm are people using/can recommend?
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Check to see if your flight controller has it, you just need a potential divider circuit and a buzzer.
 
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These are some of the things that I've learned in the process of putting these things together.


Motors
With regards to the motors I'd generally look for something in the 70-90g weight range with around a 1000-1200kv output, a bit higher or a bit lower doesn't hurt either way. With the ESCs I'd generally aim for 18amp and up simply because once you get hooked on RC and on building these things the only way is up and once you start getting beefier motors then they draw a bit more current. For your first quad you can get away with 12amp but your demand for more 'mumbo' will have you buying them with a higher rating in no time. (a note here - I went with a higher kv in that I wanted throttle response and aerobatic capability, the lower kv motors are better for FPV and overall lifting stability)

The kv rating is translated like this: kv = rpm/volt. So a typical 3 cell lipo has 12.6volts fully charged. So a 1000kv motor will run at (12.6x1000)rpm or 12600rpm.

Motors come in a range of options the most appropriate for Quads generally being brushless outrunners. Outrunners have two different mounting configurations just to confuse things, with the bell above or below the base, either is good but by the base makes the overall build and balancing a bit easier IMO as mounting below leaves the motor hanging below the arms of the quad. It also leaves you with a longer shaft which is quite prone to bending when you crash and getting them back true and balanced is a hell of a trick.

I started with these little suckers (same as the OP) and they have stacks of oomph and are cheap as chips:
http://www.giantshark.co.uk/emax-cf2822-outrunner-brushless-motor-p-53.html

Be warned though, they have fairly soft shafts which can bend if left long so consider cutting them down.

The other thing that is worth keeping in mind with outrunner motors is that to change the direction of rotation you should switch any two wires.

ESCs
electric-speed-controller-esc.jpg

ESCs (Electronic Speed Controllers) are a whole voodoo on their own. They do two things of note. First, like their name suggests, they control the speed of the motor depending on the signal input. Second they change the DC current from the battery into a 3 phase AC current hence the 3 wires on the motor.

(A good thing to mention here is to not try attaching the motor to the battery without an RX and an ESC inbetween. It won't work and it will likely blow up the motor).

ESCs are generally programmable meaning that you can tell it how to behave in various conditions, such as what type of batteries you have connected, where you want the throttle end points and whether you want a soft start/cutoff or a hard start/cutoff. With Quads this is important because some ESCs have a set behaviour of a hard cutoff when they reach a certain voltage. This is bad because when you have £250 of your money in the air and the ESCs decide you're out of juice they will just turn off the motors. Programming the ESC to think that it's connected to a NiMH batt means that it will have a soft reduction in throttle response as your voltage runs low. A much nicer proposition. Programming an ESC is normally done via the transmitter but you can buy programming cards which tend to be a bit easier.

The next gotcha with ESCs is that they have a formatted (in the Firmware this time) update rate that may not be fast enough to deal with the signal coming from the flight controller. This is bad. Flight controllers send out updates at around 400Hz and some ESCs have not been programmed with this in mind (actually most have not) so any old ESC will not do. There is a movement within the Quad community to reflash their own ESCs and I made the mistake of not doing my research on this and bought some that can't be reflashed. The way around this is to buy ESCs that are preflashed with Quads in mind.

I found these guys that sell exactly those for very reasonable prices:
http://gothelirc.com/shopdisplayproducts.asp?id=138&cat=iPeaka+ESC

Why is the update rate important? Basically the controller tells the ESC to speed up or slow down the motors to keep the quad level. If the signals that the controller are sending out are getting ignored by the ESC (or partially) then the required response is not going to be sufficent and the subsequent correction has to be larger. ESC ignores again and the next correction is even bigger and then next thing you know you have an increasing oscillation occurring and your quad drops out of the sky.

Like this at around 58 seconds and then at 1:17:

ESCs have a whole swag of wires hanging out of them. You have the obvious red and black that are the positive and negative connectors that go to the battery, but then you have three coming out the other end that go to the motor, any to any again reversing any two to change the motor direction. And the last one is what they call a BEC or a Battery Eliminator Circuit (the small 3 wire with the servo connector on the end). This has two functions, the first being to carry power from the battery, step it down from 12V to 5V (Red and black wires) and the second to pick up the signal (typically brown/orange or white) from the RX or the flight controller and tell the motor what you want to do with regards to throttle. Attaching these to the RX or the flight controller in the right orientation is very important because the stepped down 5V is the thing that powers the onboard electronics. Because on a Quad you have 4 of these a common practice is to extract 3 of the 4 red wires so you're only powering from one ESC. In my experience it's not always necessary but it is prudent because you could induce problems with either too much current or messy signals.

On a quad copter the Flight controller subsequently powers the RX whereas on a normal fixed wing plane the ESC would power the RX directly.

Flight controllers

This is where the magic happens and what makes Quadcopters able to work the way they do. Quads use two specific techniques to allow them to fly, the first is obvious, the thrust from the motors and props pushes either a corner or a side up, a combination of which gives you roll and pitch. They also use the torque from the motors and props to twist the quad about it's axis, or yaw. To tell the quad what it's orientation is, the flight controller has 3 electronic gyros built onto the PCB - one on the x axis, one on y and one on z. This is the fundamental base for all controllers and what gives a quad it's inherent stability. It resists any external and unwanted input by speeding up the opposing motor till the orientation is back to where the quad originally was.

There are a range of capabilities that people are putting into their quads, things like altitude hold, auto leveling, GPS positioning, UAV style map following and all sorts of other cool things that cost an arm and a leg to build. Personally I'd aim low and see how you go with something that just has the standard gyro stabalisation. Something like the Hobbyking Multi-Rotor Control Board or the KK Multicopter Controller Board

Before you buy though I would strongly suggest reading up about the various options and deciding what it is you want to do with your quad, i.e. aerobatics or FPV etc.

Quads fly in two differing configurations, + and X. I prefer X because it has a better roll rate and I find it easier to follow. Normally if you buy off ebay and the like you need to tell them about the orientation you prefer.

I mentioned that quads use the torque of the motors to produce yaw. The way they do this is by having two motors running clockwise and the other two running counter clockwise. Getting this wrong and plugging the signal leads into the controller in the wrong order can be damn confusing to sort out. RTFM is deffo your friend here. To better understand the configurations take a look at this. Warning though - this is not a gospel for motor configurations - some controllers do use a different layout.

firmwares.jpg


Batteries
Battery technology has come a long way recently and like the OP said LiPo or Lithium Polymer batteries are pretty much the standard. I'll keep this short. I, like many others, have found 2200mah 3cell 25c batteries to be a weight vs flight time sweet spot. You'll get around 12-15 mins of hovering and floating around flying at around 50-70% throttle which is stacks. They take around 1hr to recharge and should never be run flat. You will hear them being described on a per cell basis, i.e. 3.7 volts charge and 11.1V capacity. This is not the actual full charge voltage, it's more a nominal voltage and one that you would build your quad around. Full charge you'll get around 12.7volts and when they're run down and you start noticing a lack of throttle response they will be around 9.4volts. Never let them get lower or you'll have to dick around with them to recharge them and they won't hold charge for as long.

LiPo batts are fairly delicate things that need to be looked after, you store them at a set charge and keep them out of direct sunlight. If they swell up (because they're in soft cell packs) then they need to get chucked. They are also fairly large fire risks and as a result if you charge them you need to keep them on a ceramic bench top or in a special LiPo bag so if they do go up you don't set your house on fire.

25C is the discharge rate or the safe current draw that the battery can handle. 25C is oodles for a quad of this size.

Read up on batteries, when you buy them, look at the weight, number of cells, voltage and C rating. What you should be looking for is somewhere around 180g, 3 cell, 11.1V and 25C+.

Transmitters and Recievers
Quads use a pretty basic control set at their root. Where a fixed wing plane used Pitch(Elevator), Roll(Aileron), Yaw(Rudder) and Throttle so does a quad. Look for a 4-6 channel 2.4GHz transmitter and receiver setup. Transmitters can be had for around £30-£60 and the receivers for around £15.

Things to look out for are the Modes. This denotes the stick configuration. Most of the world operates on Mode 1 - being Elevator and Rudder on the left stick and Throttle and Aileron on the right stick. America operates on Mode 2 which is Throttle and Rudder on the left and Aileron and Elevator on the right. I'm a little odd as I operate on Mode 3 or XBox/Playstation mode - Elevator and Aileron on the left and Throttle and Rudder on the right - Why mess with years of ingrained habit I say.



Propellers

Last but definitely not least are propellers. Propellers for quads come mostly in two flavours, Slowfly and Thin Electric. Slowfly props are the best place to start, they provide better thrust at low rpm and longer hovertimes. The downside of them is that they weigh more and draw more current when you want quick throttle response which is where you would transfer over to the thin electric style.

As I explained earlier, quads use matched pairs of clockwise and anticlockwise spinning motors to provide yaw. Unfortunately no matter which way you mount a normal propeller you will always have it blowing up rather than down on a reversed motor, so you need to get a specifically designed reversed prop. When you buy then get them in sets and get a fair few of them, as in 6-8 sets. Sods law says that you'll almost always break the special reversed direction props in crashes!

What you want to be looking for is the following. 8-10inch, 4.5-5 pitch matched pairs. These guys sell a good selection.
http://www.giantshark.co.uk/pair-1045r-slow-counter-noncounter-rotating-props-p-406234.html

With propellers you will almost always need to balance the props. This is especially true with quads and the like because vibration is not your friend - the gyros do not like it and you will have difficulties finding smooth flight if you don't balance things properly.

Have a look at this to learn how to do it.


So I hope this makes sense - please ask if you have any specific questions and I'll try to point you in the right direction.

For a starting shopping list I'd go with:

A decent frame, I'd be inclined to go with a good fiberglass frame rather than the plastic one you posted earlier. It will stand up to crashes a bit better. Or possibly an aluminium and fiberglass combo frame. I got mine from here and it's awesome - it's fallen from about 25feet and come away unscathed http://quadframe.com/collections/quadcopter-frames/products/quad004

Motors - you need 4 but I'd get a couple spare, at £8-£12 a pop having the spare ones around will save you some grief when you have a particularly bad crash

ESCs - 4 will do as long as you treat them nicely - if you're feeling rich get a spare but they don't go fizz as long as you don't do anything silly. Remember to not get caught out with the update speed. More and more suppliers are saying if they are appropriate for multicopters or not.

Batteries - Get 3 or 4, means you don't need to keep waiting for charging and will give you more than enough flight time whilst learning or down at the park.

Flight controller - Do the research and try and figure out what you want from it. I've had good experiences from the KK controller. I can't really speak to the other ones. Read up on RCGroups.com and see what others think.

Transmitter and Receiver - remember 2.4GHz and 4-6 channel, more if you're rich.

Wire - you will need to figure out a way to distribute the power from one battery to 4 ESCs - I used something called a power spider that I put together on my own. Instuctional vid here http://youtu.be/Tn2Nt3sjsI0
Other people used specifically designed power distribution boards, either way you will have to learn to solder. Really with soldering Youtube is an amazing source of learning.

Assorted items:
Locktite Blue
Velcro Strips
Gold Bullet connecters x20 or 30 (http://www.hobbyking.com/hobbyking/store/__67__4mm_Gold_Connectors_10_pairs_20pc_.html)
TX60 connectors -get a few of these because you'll need them for new batteries. (http://www.hobbyking.com/hobbyking/...0_Connectors_Male_Female_5_pairs_GENUINE.html)
Heatshrink 4mm
Soldering Iron
Flux Core Solder
Soldering Helping Hands (http://www.ebay.co.uk/itm/Third-Hel...Home_Garden_PowerTools_SM&hash=item5ae6353ef3) These are a godsend.
Small Zip Ties
Prop Savers 3mm (http://www.giantshark.co.uk/30mm-prop-saver-p-402344.html) if you get these make sure you order some of these too (http://www.giantshark.co.uk/rings-prop-saver-20mm-20pcs-p-407327.html)
or Collet type spinners (http://www.hobbyking.com/hobbyking/store/__19593__Propeller_Adapter_Colet_Type_Long_3mm.html) (careful with these that they actually fit both the motor shaft and also the hole in the prop)
Hot Melt Glue Gun


That's all I can think of for now. Let me know how you go.
 
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Great post Steve and looks like it covers the main bits I was wondering about!

I like the frame you've got. Would you recommend buying any obvious spare parts for it in case of breakage?

I've already got a soldering iron as I replaced the DC jack on the wifes laptop a couple of years ago. Is it worth buying any sort of kit to learn / practice soldering on?

If I'm going to build over a period of months what parts should I buy in what order?

Are there any recommeneded battery chargers?
 
I've crashed my frame quite a number of times and it's never come close to breaking. It's a beautifully machined frame and solid as hell whilst being pretty light. With the combo of motors you get around 3.2kgs of thrust for a machine that weighs only 800-900gms including the battery.

Start with the frame, ESCs, Motors. That will give you the chance to get the frame set up and the rigging done. The second stage would be Flight controller, batts, charger, and transmitter and receiver.

Practice with the soldering I'd do with just joining wires, learn the technique of heating the contacts to get the solder to flow and also 'tinning' the surfaces before joining them. Also have a read of this: http://www.elexp.com/t_solder.htm and watch this http://www.youtube.com/watch?v=BLfXXRfRIzY

Chargers - I have one of these http://www.giantshark.co.uk/imax-balance-charger-clone-p-406640.html Oh and before you plug a battery in to charge it - read up about the maximum charging current and understand how the charger interacts with the batteries.
 
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I don't get the military done use these in the field as recon drones of some kind.. would help our boys would it not.. look at how cheap us civilians make these things... and there not used in the military?? what kind of nonsense is that.
 
SteveOBHave said:
I've crashed my frame quite a number of times and it's never come close to breaking. It's a beautifully machined frame and solid as hell whilst being pretty light. With the combo of motors you get around 3.2kgs of thrust for a machine that weighs only 800-900gms including the battery.

Start with the frame, ESCs, Motors. That will give you the chance to get the frame set up and the rigging done. The second stage would be Flight controller, batts, charger, and transmitter and receiver.

Practice with the soldering I'd do with just joining wires, learn the technique of heating the contacts to get the solder to flow and also 'tinning' the surfaces before joining them. Also have a read of this: http://www.elexp.com/t_solder.htm and watch this http://www.youtube.com/watch?v=BLfXXRfRIzY

Chargers - I have one of these http://www.giantshark.co.uk/imax-balance-charger-clone-p-406640.html Oh and before you plug a battery in to charge it - read up about the maximum charging current and understand how the charger interacts with the batteries.
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Steve, what amps would you need for the ESC's if I went for those CF 2822 motors? As the motor specs says that it draws max 12 amps do I need to be looking 22 amps ESC's?
 
Hi guys, I fly RC planes for last 10 years or so now. I am interested in this FPV though.

Is it expensive. Light etc? Let me have some details of cost and what is needed, could be interested in getting this into one of my models.

Could be a lot of fun and another area of RC i have yet to explore.


Thank you
 
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