The battle of the portable selfie drones

Watch the live launch of the DJI Mavic here: http://live.dji.com/adventure/

Three selfie drones are going head to head this autumn. We have our own thoughts about which one will win. The competitors are the Yuneec Breeze, the GoPro Karma and the DJI Mavic.

I’m going to add more to this blog post as we find it out and as we get our hands on the drones. I don’t like to judge drones too much until I get my hands on them.

 

 

 

A Plethora of Phantoms

The DJI Phantom is now probably the most popular consumer drone on the planet but, with a new model coming out almost every month, which is the right one for you. This is a very quick summary of the different models based on my own experience. For further reading please have a look at the DJI products page. In the absence of a collective noun for Phantoms, I am suggesting a “plethora”! 🙂

DJI Phantom 1

The original DJI Phantom with Naza-M flight controller. No stabilised camera gimbal but does have a mounting bracket for GoPro. Uses standard lithium polymer batteries rather than the newer intelligent batteries. DJI are no longer producing them but you can pick them up cheaply on eBay so can make a good, cheap machine for learning basic flight skills. Flight times are short, but OEM batteries are cheap as chips!

DJI Phantom 2

The DJI Phantom 2 was a real game-changer in the consumer drone market. The “intelligent” batteries make for a simpler, if slower, charging experience and allow flight times of up to 23 minutes or so. Initially the H3-2D gimbal was frustrating as it gave a characteristic ‘headshake’ to the video as there was no yaw axis correction. However, the H3-3D and H4-3D gimbals really began to show what a small machine can do.

The Phantom 2 comes in two main flavours, the standard Phantom 2 carries a GoPro whereas the Phantom 2 Vision range (now discontinued) carry DJI cameras. The Vision range connect directly to a mobile phone or tablet using the DJI Vision APP whereas the GoPro versions require the addition of a 5.8GHz downlink.

The Phantom 2 is a great starter machine but as it contains the DJI Naza flight controller, the GPS hold and flight characteristics can occasionally be a little poor compared to the newer aircraft.  However, as they can be obtained from new at around £600 and probably cheaper in used condition, they can make a great starter machine for HD and 4K aerial videography. If you are looking for second hand Phantoms (always a risk in RC aircraft) I suggest you look out for the H3-3D or H4-3D options rather than the H3-2D as there is a marked improvement in video quality as mentioned earlier. Also, check carefully to see what accessories you are getting and if a downlink is included. People who are upgrading often strip downlinks to use on other aircraft.

It is also worth bearing in mind that the Phantom 2 batteries cannot be used in the Phantom 3 and vice-versa due to a change in voltage.

DJI Phantom 2 with H4-3D gimbal

DJI Phantom 2 with H4-3D gimbal

DJI Phantom 3

When a friend of mine told me to try a Phantom 3, I was a little sceptical, wondering how much better it could be. However, with an upgraded flight controller and a camera that is close to the quality of the DJI Inspire 1, it punches way above its weight. We have a DJI Phantom 3 and an Inspire 1 that we use for our drone flight training courses and they go down very well with both experienced and novice pilots.

The Phantom 3 has much improved flight characteristics and GPS hold than its predecessors and, again, comes in several flavours. The Phantom 3 Professional has the same 4K camera that is in the Inspire 1, but is only a single operator machine, whereas the Inspire can be operated either as a single or dual operator machine. The Phantom 3 Advanced has a 1080P camera, which is similar to that on the Phantom 3 Standard. However, the Phantom 3 Standard, which replaces the Phantom 2 Vision+, does not include the Lightbridge technology which is part of what makes the Phantom 3 such a leap forwards.

The Phantom 3 Professional and Advanced feature the Lightbridge, which allows a 720P HD downlink to a tablet or phone. The quality is much better than previous downlinks and even allows live streaming to Youtube. I do find, however, that sometimes there is a bit of latency on the digital downlinks that you don’t tend to get on the analogue downlinks.

The downside may be that there is no DJI system for adding ND filters to the Phantom 3, but there are aftermarket push-on filters available.

The Phantom 3 Professional and Advanced work on the same DJI Go APP as the Inspire. A bit of a difference on the transmitter, compared to the Inspire, is that the Phantom 3 has no HDMI out for live streaming to a monitor or other output device, but that can now be added with a small HDMI output upgrade module.

Personally, I purchased the DJI Phantom 3 Professional with extra battery and hard shell backpack. We recently took it on holiday with us and the backpack proved its worth, both in portability and protection.

DJI Phantom 3 Professional with free battery and hardshell backpack

DJI Phantom 3 Professional with free battery and hardshell backpack

If 2014 was the year of the drone, let’s make 2015 the year of the payload!

Admittedly, year of the payload doesn’t sound quite as exciting as year of the drone but it has to be the way forwards for a number of good reasons that I’ll try to expand on in this post.

But first, Happy New Year to all our friends and followers. I hope 2015 is a good one for you!

I often get asked what drone I fly and so end up having long discussions about hexacopters and octocopters in various configurations. Bizarrely, we don’t end up talking about the camera payload very quickly in most cases. The same happens when I get asked to consult on equipment where the conversation often goes something like:

“I’m thinking of buying a drone.”

“OK”

“I’ve done lots of research and I’ve come down to (insert several drone names with a distinct ghostly or terminator  theme)”

“OK, great, what camera are you thinking of flying?”

“Erm… I haven’t thought much about that, the best I can I suppose.”

If you can imagine the same conversation in a camera accessory shop but insert “tripod” instead of “drone”, you begin to see the problem.

Drones have changed a lot over the last couple of years, moving from aluminium framed box section creations lovingly crafted in sheds and garages to much more uniform designs churned out by the thousand. Reliability is improving, failsafe features are getting there. As a result a proliferation of drone use is occurring, causing a few understandable shockwaves in terms of privacy, legislation etc. that I’m sure will iron themselves out eventually.

So, whilst drone development will continue for a long time to come, it is time that we begin to see them for what they are (at least for the majority of the industry), flying tripods. Incredibly versatile tripods, but tripods nonetheless. Yes, they are fun too at times, but they are still a tripod! As a result we need to be encouraging people to consider payload as the priority and then matching the appropriate UAS to give a total solution.

So what can a change in focus do for the industry? A few ideas that people may wish to discuss.

  • Reduce public fears over drones

Once people begin to look past the drone itself it becomes much more possible to sell the advantages of being able to carry a sensor payload into useful situations without, for example, putting employees into dangerous situations themselves.

  • Allow meaningful conversation with customers

Generally my customers have no interest in whether I am photographing from the top of a ladder or flying the latest cutting edge drone. All they are really interested in is the end product. It makes much more sense to focus on the end result and the payload than the drone itself.

  • Allow effective research and development collaboration

We can make almost anything fly but, at the end of the day, if my sensor payload doesn’t acquire useful data, I may as well not bother. If we begin to discuss payload, and ultimately the data to be acquired, we can generally work backwards to a drone solution that will carry the payload appropriately. This means working closely with end users to develop the complete system.

  • Allow current legislation to be employed for data protection and privacy

A lot of time and effort is being wasted in trying to write new legislation for drone technology. In the UK particularly the CAA has worked hard to develop workable legislation, it may need some fine tuning, but I don’t feel it needs much. We also have perfectly adequate data protection legislation to deal with privacy issues when it comes to cameras. Separating the payload from the drone allows these two issues to be considered independently and much more logically.

 

Now that the industry is maturing, it also seems to be logical to begin to think about universal payload mounts and power connections but I suspect we are quite a way from that yet.

Just some thoughts, feel free to come and discuss them over at the HexCam website or Facebook.

Anyway, let’s raise a glass and welcome 2015, the year of the payload! 🙂

Versadrones Versa X6

A Versadrones tripod!

Elliott – HexCam

 

Lithium polymer battery chargers for multirotors

This follows on from my post on lithium polymer batteries but I just need to put in the same disclaimer!

I get a lot of questions about multirotor equipment so I thought I’d start creating some posts about that. Please bear in mind that I learn a lot from reading around the blogs and forums and talking to people in RC shops so any inaccuracies are completely due to my own misunderstanding. By reading this you accept that, although I hope it will aid with your own understanding, it is written in good faith and I can’t take responsibility for any damage to yourself or your equipment that occurs through the use of this information. If you see anything that I have got wrong or you feel is dangerous, please contact me through the HexCam website or Facebook page and I will rectify it as soon as possible. Please treat lithium polymer batteries and multirotors with same respect you would give to other electrical and mechanical equipment. Look after them and they will look after you.

You also need to know the following: I am not paid to review or endorse any products but I do have a partnership arrangement with Versadrones to act as their demonstrator and trainer in the UK.

Introduction

Getting the right lithium polymer (lipo) battery charger can be a real minefield. The main reason for this is that often the charger companies only tell half the story. So I will try to clarify it, but am not going to promise anything as I sometimes still get a little confused myself. It is, however, vitally important that you get the right charger for the kind of aerial imagery business you are running. If not, you will find yourself very frustrated. A decent battery charger and power supply can be pretty expensive. But as someone who has a number of “retired” chargers around the office, I would say that you need to see it as an investment. A good charger will maintain battery health, allowing batteries to remain in use for more charge cycles, it can also save you time if you don’t have to be monitoring the charger continuously just to get all your batteries charged in time! If you look across the net you’ll find all kinds of homebuild arangements for providing power. There are ways of doing this, and I have done so myself on occasion. However, I am also aware that for most people the idea of stripping down a server power supply is pretty daunting, so I’m going to focus on professional solutions that might just survive a portable appliance test! If you are up for a bit of homebuilding just have a look around the RC forums. People have built some amazing setups.

What do I need to start charging lipo batteries?

The first thing to say here is that lithium polymer batteries need a specific lipo charger. If you try to charge them with anything else you are risking a fire. The technology (and people’s understanding) has improved over the last few years. If charging indoors, keep the batteries in lipo bags or some kind of metal case.

You are probably going to want two things… a mains operated charging system that can be used for charging back at base and a mobile system while you are out operating. Generally, the charger will be the same but your power supply will change. If you have bought something like a DJI Phantom you will get a neat little all in one plug and charger with it. No problem for small batteries like that so just get on with it and fly! I would still suggest following the 20% rule from my lipo battery post though.

It is recommended that batteries are charged at a 1C charge rate. This means a 3000mAh battery should be charged at a maximum of 3 amps, a 5000mAh battery at 5 amps, etc. Many batteries are now rated for higher charge rates but there is a possibility of battery chemistry damage if high rates are used too regularly. If in doubt, charge at 1C or below. There are ways of doing this efficiently!

The parts of a charge station and lipo battery storage

  1. The balance charger
  2. The power supply (home)
  3. The power supply (field)
  4. (optional) Parallel charge board or harness
  5. Lipo bag/box

1) The balance charger

I have just sat for about 5 minutes trying to work out how to start this so it may be a little incoherent on first release, I will try to hone it later. Most people find that their first charger is underpowered and wonder why it won’t charge their shiny new 6S lipos in under three hours! When buying a charger, you need to look for several things: input voltage, output voltage, maximum current (amps -A) and very importantly maximum power output in watts (W). I’m going to start by considering charging a single battery on a single channel charger as it is where most people start. Something like the imax B6. When you look at the box below, you think great; it’ll charge up to 5A, so my 6S 5000mAh battery will charge fully in an hour no problem… it even says so on the box… Right?

iMax B6 lipo charger

iMax B6… my first charger.

Wrong. It is true that a 5A charge would give a 1C charge rate for a 5000mAh battery (5A = 5000mA). However, what this doesn’t take into account is the battery voltage or total wattage of the charger. The charger has an input voltage of 11-18V and a total power of 50 watts (not found anywhere on the box).

In this example, I am using an 18V power supply capable of delivering 540W. As a result it can potentially power more than 10 of these B6 chargers at a time.

As you can see from the next photo, the charger will only charge at 2.2A (less than 0.5C). The reason for this is that we are trying to charge a 22.9V battery at a maximum of 50W.

iMax B6 charger

The iMax B6 trying to charge a 6S 5000mAh lipo.

Here is a simple equation: W = A x V. By rearranging that we get: A = W/V.  So 50 divided by 22.9 is…. 2.18A. So basically, this charger is maxed out as it has hit the maximum 50 watt limit. At this rate the battery will take about 2 hours to charge. The B6 also has a 240 minute timeout set as standard (a good safety feature) so it may time out before it charges.

We can quickly work out the maximum battery size that will actually charge at 5A on this charger using the same equation as before.

Rearranging it again we get: V = W/A

So the maximum voltage that will charge at 5A is 50 divided by 10: 10 volts.

Remember a 2S lipo has nominal voltage of 7.4V and a 3S is 11.1V. As a result, this charger would charge a 2S lipo at 5A but as soon as you get to 3S or more, the wattage will max out. This charger does have its uses; I now use it to charge my 2S and 3S AV receiver and LCD batteries as it is a good lightweight charger and frees up my main charger for the big lipos.

This next charger, the Hobbyking Eco 6-10 is very similar to the B6 in most ways. In fact, the user interface on a lot of these chargers is identical. You do have to manually choose a normal charge or balance charge.

Hobbyking Eco 6-10 charger

A step up from the B6

As you can see, with this charger I put in exactly the same settings and am getting a constant 5A charge. So what is the difference? Well, the big 200W on the front gives a major clue. The battery is currently at 23.75V as you can see if you enlarge the photo. Going back to our equation: A = W/V… 200W divided by 23.75 is 8.4, so theoretically this charger could charge my 6S lipo at up to 8.4A at this stage of the charge cycle.

This charger will give a maximum 10A charge so I set it to that to see what would happen. As you can see from the next photo, The wattage has become the limiting factor as suspected and we are limited to 8.4 amps, which on this battery is a 1.7C charge rate (this battery is rated up to 5C charge).

Hobbyking Eco 6-10

I set this up for a 10A charge but it is limited by maximum wattage to 8.4A

In the words of the great Professor Brian Cox “…and that’s why I love physics!”

It is completely predictable, if you know your batteries and can use one simple equation you can work out the minimum requirements of your charge system for the batteries you are going to use.

There are variations on these types of charger so that there are multiple chargers in unit. There are a few out there, that are basically four iMax B6 chargers in one box. The key thing to look for there is the wattage again, particularly with respect to the maximum wattage each channel can support.

My current charger that I use both in the workshop and out on projects is the Fusion Emperor L712B Pro. This is a two channel charger capable of 500W per channel.

Fusion Emperor L712B Pro

This charger gets taken everywhere!

As you can see, both channels are plodding away at 5A no problem. There is also no balance charge option on this charger, the balancing is part of every charge (evening the individual cell voltages out so that they all end up as close as possible to 4.2V).  It also gives you % charge and loads of other useful information on other screens.

At 500W (max 20A) per channel, using the equation A = W/A and the information from the bottom channel on the photo:

500/23.94=20.88A, so I could charge this battery at the maximum 20A (a 4C charge rate). Alternatively I could charge 4 of these batteries in parallel at 5A on each channel, meaning I could charge 8 6S 5000mAh batteries in one hour.

Right?

Wrong.

2) The power supply (home)

At this point a new limiting factor has come into play. In order to use the maximum 500W on each channel, I need to be able to use 1000W of power. You may remember, this power supply only provides 540W, so I’m going to be able to use about 270W per channel which means with this power supply I will only be able to charge 4 lipos at the 1C rate. In order to get the full potential from your charger, the power supply you are using must be able to supply at least the same wattage as the charger, so all I need to do to be able to charge my 8 batteries at a time is to buy a minimum 1000W power supply and it is sorted. Right? Pretty much! Just check that the power supply is also able to supply the minimum amps required too. Also, the charger will work most effectively if you are able to supply power at a higher voltage than the batteries you are charging. So to get the most out of my Fusion Pro I need a power supply that will provide a minimum of 40 amps at 24V and a minimum of 1000W total power. There are some people who will realise it isn’t quite that simple, but I’m trying to keep it as simple as possible. Make sure your power supply voltage does not exceed the voltage of your charger or you will blow it up! For example, I wouldn’t use the iMax B6 ona 24V supply as it is only rated up to 18V.

Something like this SkyRC power supply is great as it has fully adjustable voltage and can provide up to 1200W at up to 50A which will easily let me use the full potential of my Emperor Pro. With chargers improving all the time even this power supply may not be enough!

All very well, but what about when you’re out filming and haven’t got an extension lead into a convenient building…

3) The power supply (field)

Up until now I have generally used a direct connection to my car battery to provide power to my charger when out on location with no mains power. I did experiment with an inverter to convert the output to AC and then plug in the 18V supply, but it was inefficient and also a mess of wires to set up. Using your car battery without the car running also runs the risk of draining the battery. Car batteries also aren’t designed to be deep cycled so you may be reducing the life of your battery. So now I am moving towards a system using either a 24V deep cycle leisure battery or two 12V leisure batteries in series to give 24V.

field lipo charger

Using deep cycle leisure batteries in Rotarama’s field charging system

Here, in a setup used by my friends at Rotarama, as you can see, we are using two 12V deep cycle leisure batteries in series to give a 24V output.

These batteries have a combined capacity of 220,000mAh. Enough to charge Our 5000mAh batteries 44 times. More actually as you’ll remember, with the 20% rule, we shouldn’t be putting more than 4000mAh in each time anyway.. More than enough for a day’s work!

If you look carefully at this picture, you will see that we currently have two batteries in parallel on the left hand channel and nothing on the right. As we use our batteries in pairs, it is logical that we charge them in parallel pairs too. Parallel charging can be carried out with any batteries of the same voltage. I feel it is best to only charge batteries in parallel if they are the same capacity and state of charge as well. You can see we are using a parallel charge board that will take up to 6 batteries in parallel.

Which neatly leads us on to our penultimate section….

4) (optional) Parallel charge board or harness

Bearing in mind the equation we talked about earlier, it may be possible to get more out of your charger by using parallel charging.

If you look back at my battery post, you’ll remember that putting lithium polymer batteries in parallel is not only possible, but can be very advantageous at times. It works with charge as well as discharge. So if I put my two 5000mAh 6S in parallel and the balance leads also in parallel using the special board (parallel boards for most types of connectors are readily available at most RC shops and online) then I effectively have one 10000mAh 6S2P battery. As a result I can charge the pair at 10A and each battery is getting the equivalent of 5A (back to the 1C charge rate). If I added a third battery I would create a 15000mAh 6S3P battery which could be charged at 15A to give the 1C charge rate.

5) Lipo bags and boxes

I don’t like to get hyped up over danger. For every scary lipo fire you may see on the forums there are literally thousands of successful charges. Also, incidences seem to have reduced considerably over the last few years as technology and understanding has improved. However, there area number of things you can do to make sure you charge safely.

  • Use lipo bags for containment in the event of a fire.
  • Store your lithium polymer batteries in a metal case. A lot of people use ammo cases!
  • Always charge on a non-flammable surface.
  • Keep a small portable powder fire extinguisher near your charge station and out on location.
  • Keep a log of battery charges. Changes in capacity and cell balance can indicate a battery that is degrading.

I hope all this helps to some degree. If you want to discuss anything, do get in touch!

Fly safe!

Elliott – HexCam

I am publishing this as I type… so more will keep appearing throughout the day.

Lithium polymer batteries and balance chargers for multirotors

I get a lot of questions about multirotor equipment so I thought I’d start creating some posts about that. Please bear in mind that I learn a lot from reading around the blogs and forums so any inaccuracies are completely due to my own misunderstanding. By reading this you accept that, although I hope it will aid with your own understanding, it is written in good faith and I can’t take responsibility for any damage to yourself or your equipment that occurs through the use of this information. If you see anything that I have got wrong or you feel is dangerous, please contact me through the HexCam website or Facebook page and I will rectify it as soon as possible. Please treat lithium polymer batteries and multirotors with same respect you would give to other electrical and mechanical equipment. Look after them and they will look after you.

You also need to know the following: I am not paid to review or endorse any products but I do have a partnership arrangement with Versadrones to act as their demonstrator and trainer in the UK.

Introduction

It worries me that people are prepared to skimp a little bit on their lipo batteries. It is worth bearing in mind that anything that can fly can fall, so I tend to look around for the best batteries I can within my budget. However, there are now a vast number of different lipo batteries, chargers and power supplies out there which leads to some confusion. I tend to buy my batteries from Hobbyking who now have a UK warehouse and have come to prefer the Turnigy and Turnigy NanoTech batteries. My reasons being that they hold good cell balance and seem to maintain battery health for a good period of time whilst being reasonably priced. I’m going to try to keep this as non-technical as possible, but when talking about batteries you have to get a bit technical. As a result I suggest you get a coffee (or maybe a beer if it is late enough in the day), maybe a notebook and possibly some biscuits as well. Sitting comfortably? Then I’ll begin…

Lithium polymer battery basics

What on earth is 3S, 4S, 6S etc?

I’m not going to go into the chemistry of lithium polymer batteries in this blog, but the basic unit of the battery is the cell. A battery is generally made up of between 2 and 10 cells in series. Each cell has a nominal voltage of 3.7 volts and a fully charged voltage of 4.2 volts. So 3S means 3 cells in series. Putting cells in series multiplies the voltage of each cell by the number of cells. A 3S battery has a nominal voltage of 11.1 volts (3 times 3.7V) and a fully charged voltage of 12.6 volts (3 times 4.2V). A 6S battery (now standard on a lot of larger multirotors) has 6 cells in series so has a nominal voltage of 22.2V and a fully charged voltage of 25.2V.
With me still?

But I saw 6S2P!!! What is that?

OK. Unlike most other types of battery, lithium polymer batteries can be connected in parallel (P) too. This is incredibly useful as it means by having two batteries the same connected in parallel you can maintain the original voltage but double the capacity. 6S2P means we have two 6S batteries connected in parallel. So, if each battery is 5000mAh, by connecting them as 6S2P we now have 10000mAh at 22.2V. In some uses this would effectively double the life of the battery. When flying, you have to take into account the extra weight you are adding with the extra capacity. As a result, if a single battery gives you 10 minutes of flight time running two in parallel will give you around 16-17 minutes. So, you lose some flight time but gain a degree of redundancy in the system in case of one battery failing. Your call! I prefer to fly with two batteries where possible.

5000 what?

This one is a bit simpler, The mAh or Ah refers to the capacity of the battery. As a compromise between weight and power we tend to use 5000-6000mAh batteries and connect them in parallel. So a typical hexacopter will run on 6S2P with each lipo having a 5000mAh capacity, giving 10000mAh to play with, of which we recommend about 8000mAh is actually used. Leaving 20% in your batteries not only gives you a safety barrier, it also means that if you do suddenly need that last bit of power on landing, it is there. Discharging a battery repeatedly below 20% will cause damage to the battery chemistry which could then fail during flight or charging.
Here is a video of one of our hexacopters. You can see the two 6S 5000mAh Turnigy Nanotechs on top. They are connected in parallel to give 6S2P at 10000mAh:

I found some more numbers! 25-35C. What’s that!?

Lithium polymer batteries almost always have a “C” (capacity) value associated with the other battery information. In fact, they may have two, one for charge rate and one for dicharge rate. The C value is the recommended or maximum rate at which current can flow through the battery without causing damage to the battery chemistry. These days batteries tend to start at around 20C for discharge (use) and can go up to around 100C. So what would a 1C rate look like? The easiest way to think of it is a 1C rate would use the capacity of the battery in 1 hour. So a 5000mAh battery used at 1C would be down to 0% after an hour. If you double the C rate it halves the time. So at 2C it would last 30 minutes and at 4C it would last 15 minutes. Most of my copters tend to use power at around the 5-6C rate when hovering, so a single 6C battery will last around 10-12 minutes. However, if I suddenly put my copter into full vertical lift it will draw more power and so the C rate will shoot up. If a battery says 25-35C, it means that the continuous discharge it can cope with is 25C with a peak discharge of 35C that should only be reached for seconds at a time. It is recommended that you choose a battery where all your usage will be at or below the continuous discharge rate. For most hexacopters 25C continuous discharge should be perfectly adequate. The discharge rates going up towards 100C are really aimed at pilots carrying out extreme flying with very rapid changes in power output, for example 3D helicopter flight. With aerial filming, the majority of flight is gentle movement and hovering.

The charge C rate

Conventionally, it is recommended that batteries are charged at the 1C rate. This means that a battery will take around an hour to charge and a little longer with balancing. However, you will find that batteries now have charge rates of up to 5C. I tend not to charge my batteries above 1.5C. Rapid charging will eventually degrade battery life. Of course if you are using batteries in 10 minutes and then they take an hour to charge, there is a mismatch in supply and demand if you are out on a long shoot. At this point you have a few options:

  1. You carry enough charged batteries to do the whole shoot
  2. You carry fewer batteries but have a charger solution that allows you to match supply and demand
  3. You have an intermediate amount of batteries and accept that as the day proceeds demand may exceed supply!

This conundrum leads me into chargers and home and portable power supplies, which I will blog about in the next installment.
https://hexcam.wordpress.com/2013/11/15/lithium-polymer-battery-chargers-for-multirotors/

I will also talk about lithium polymer battery safety soon as, although the safety has come on a long way in the last couple of years, lithium polymer technology should still be treated as potentially volatile, particularly when it comes to storage, transport and treatment after a crash.

Fly safe!

Elliott – HexCam

Ye’ canna’ change the laws of physics!

I can't change the laws of physics...

I can’t change the laws of physics…

So true, Scotty, so true.  (Or “I can’t change the laws of physics” to give the proper quote before I am lynched by the trekkie police!)

It’s pretty simple really. A multirotor is a flying machine carrying a fixed mass. That mass is comprised of the airframe and associated flight components, the batteries and the payload.

Now, with the payload I carry on my octocopter, I know, with the batteries I use, that I will get about 10 minutes flight time under normal operational conditions. This will leave me with about 20% charge in the batteries and if necessary a bit of oomph to deal with any issues that may arise on return and landing.

We are beginning to get a lot of enquiries about equipment supply now, via our own HexCam website and the Versadrones site.

Most enquiries include something along the lines of:

How long can it fly? What weight can it carry? How high can it go? How fast can it go?

So I generally reply asking what the customer would like to achieve. Again, often the reply is something along the lines of:

Up to an hour flight at an altitude of 1000m carrying a 5D. Now, that is a fictional example but some of the actual enquiries have been even less realistic. Let me tell you now, there isn’t a multirotor in the world that could do that at the moment. Some companies claim long flight times. I have seen up to 90 minutes listed. I don’t believe that, at least under operational conditions. If they did, it would be a low hover so ground effect assists lift, in non-working conditions with a minimal payload. If they make these claims, ask them to provide an uninterrupted flight video showing the mass of the payload and the conditions of the test and the battery condition before and after (we will be doing this with Versadrones stuff when we have some time).

With current battery, motor and propeller technology there always has to be a compromise within the total aircraft mass. You can carry a heavy camera, but not for long. You can fly fast, but not far. You can increase endurance at the expense of payload.

If we could make a machine that would carry a 5D for 45 minutes, we would sell thousands. At HexCam and Versadrones we like to give you realistic flight times and capabilities, so our flight times will always be under operational conditions, eg. carrying a particular camera and with some moving flight and hovering as you would expect in a normal aerial photography job.

So, can we build you a machine that will carry a 5D for 45 minutes? No

Can we build you a machine that will carry a 5D for 10 minutes? Yes, and it’s amazing what you can get done in 10 minutes if you plan properly.

Can we build you a machine that will carry a GoPro for 20+ minutes? Yes.

Will it be the same machine for both? No. Think of it in terms of cars… You wouldn’t drive a pickup truck in an F1 race. We try to match the machine to the job. Our new heavylift octocopter (below) will carry a GoPro of course, but not as efficiently as a smaller machine optimised for the job. Our small GoPro machines won’t get off the ground if you gaffer tape a 5D to them (goodness knows, we’ve tried!).

Ye’ canna’ change the laws of physics!

Elliott- HexCam

Versadrones heavylift octocopter

Versadrones Heavylift octocopter capable of carrying up to 4Kg payload.

Versadrones heavylift octocopter

Heavylift octocopter, capable of lifting 4Kg payload, with 3 axis gimbal, set up for two operators.

It’s small but it’s not a toy!

A thought: The fact that something is small does not mean it is a toy.

I get a lot of brilliant responses to the octocopter. As discussed previously they are almost always positive with the odd half-joking half-petrified “big brother” type comment. Invariably I get asked if people can have a go. The answer has to be no.

I’m sorry.

I think part of the problem is that, well, it does look like a toy. It has a radio-control, it’s cool, people buy into it as the dream job.

The reality is it is a small aircraft, it has 8 knife-sharp propellers rotating at considerable speed and 90% of my job is making sure we use it safely and have permissions and briefing in place to allow that to happen. If I am on a building site, like I have been a lot recently, there are site surveys, risk assessments and method statements to write, then I have to make sure I am wearing the correct PPE and that everyone on the site has theirs on. Insurance cover is sorted with emergency details covered as part of our Ops Manual. I enjoy flying but it is usually a relief to bring the copter down, download the footage and know that I can go back and prepare the images for my customer in the knowledge that the operation went well. Then comes the follow-up, post-flight checks, checking props and motor and airframe for signs of wear. Cleaning dust from the camera, camera mount and electrical systems, recharging batteries, filling in flight and equipment logs and downloading the blackbox data for future reference. When I can’t fly outside because of the weather I use a simulator to keep my skills fresh just as commercial airline pilots do if they haven’t flown for a while.

It’s small, but it’s not a toy.

The closest analogy I could think of is a drill. You get drills on oilrigs tens of metres high, bench drills, hand drills, pneumatic drills, cordless drills and Dremels. They are all different sizes and all potentially dangerous. Aircraft are the same now. We are used to working aircraft being big because, in the past, you always had to be able to fit a pilot inside. By moving the pilot outside, you can make the aircraft smaller but still just as useful. By moving the pilot outside you create safety issues that didn’t exist with the pilot inside.

Of course, you can buy toy drills made of plastic and you can also buy toy copters.

If you would like a toy version I can point you in the right direction or even sell you a starter rig, but even then you still have to promise me to be very very careful and to learn and take it slowly.

So, if you see us flying, please wait until I have landed before you come to chat. I am always happy to talk to people about the kit if I have time, but please don’t ask me if you can have a go because I’ll only have to disappoint you. I always bring the simulator to trade shows and you are more than welcome to have a go on that!

Elliott – HexCam