Hi, this is my helicopter project!
PART 1 INTRODUCTION

I got a helicopter nearly 2 years ago for Christmas, it was ok but only flew 4-5 times before the final crash left it in need of repair. I was never totally happy with it and felt it had a few flaws.
I got it from a small toy shop 40 miles from where I used to live in Devon,the guy in the shop said he had 12 of my type and 12 of a upgraded model, he took every ones contact details and tried to start a flying club for them on a Sunday morning. I went 3 or 4 times and I got to fly the other version, because of the distance and the fact I managed to crash mine badly, I didnt go any more on the Sunday mornings.
When I first started to do this project I put some details on another forum, I have learnt that some of the assumptions I had made about my helicopter were wrong, this dosnt change much, but it does change a few things I was going to do, someone also gave me a very handy link to some spares for it in the UK. I am unlikely to buy spares except maybe the main shaft, I prefer to fix and alter this by rummage/samples/junk/recycling.
Sorry for the quality of pictures, I was using mums telephoto lens but she needed it back, this thread will document my journey, I will update regularly with pictures.
Before I detail my ambitious plans, here is a picture or two of how it is now

 

Because of those on a slow connection, and because I hate the way attachments are done on this software,I shall post in small chunks .

So what is wrong with it now? I cant find the radio control unit, this has been misplaced when we moved house, I wanted it for some test's and hope to find it, but it dosnt matter in the long run, as you will see shortly I intend to build my own unit and ground control system.

The battery charger has gone, but then again the battery pack has never been good and I fully intend to try and upgrade that.

The rear bar has a nasty bend in it, you can buy a new one but the cost is high because it comes with alot of other parts I dont need, I have straightened it as much as I think it can take, but I will replace it at some point,I have a broken carbon fiber fishing rod that I could use part of for it.

The top rotor bar from the main gear wheel is bent, I have tried as much as I dare to straighten it, the replacement again costs more than I am willing to spend for now, it has been bent from the first flight and isnt too bad.

Batteries
These are LI chemistry of some sort (I have forgotten and need to look it up again), there barely held a charge from the day I had them! They are history and to be replaced with a dual battery pack, the reason being, the upgraded one I flew had a dual battery pack and flew longer, but most of all it was heavier! Mine is too light, when you start to take off you have too give it some wellie first, if you dont the stabilizer bar catches on the top rotors (nasty,very nasty), the trouble is it dosnt take off in a steady manner, it goes from on the ground to roaring up in the air with very little movement on the joystick.
In some ways at least it shows the motors have some grunt, these I am keeping for now, I at first thought they were brushless, but apparently not, so I am going to eventualy replace them.

Electronics
Well there going! all of it! This is where I am making the biggest changes, to start with I am making it semi autonomous, then maybe fully autonomous, I intend to use a ARM CORTEX M3 or M4 processor, it will have a gyro,magnetometer,compass,accelerometer and at some point a GPS module. I know I have to watch the weight, but with what I have in mind, the extra weight wont be that great and will help it become more stable, the modified one I flew took off much better than mine.

The skids
These are too close together, sometimes the helicopter can flip on its side if you take off too slow, also I want them a little taller, I am not sure what I will make them from yet, but that will come to me.

Bodywork
The bodywork was thin plastic, it looked ok but could have been much better! I am going to make 3 sets of bodywork but more on that another time.

Radio control

This is being replaced with a 868 MHz 8051 MCU with built in Transceiver, I have a couple to choose from and I have 2 antenna dev kits for them, I will post pics of that stuff later.

For now here is a pic of some the dev boards I can choose from my dad's 'stash', I will explain later what I intend with the electronics, I cant use all this stuff I have o choose, but as you can see, my dad has a good selection DEV BOARD PORN!

Oh and a close up pic of the nasty bend

 

Very cool project!


Once thin, aluminum tubing has a kink in it, it's almost impossible to repair it.

Should be a online store who sells the tubing.

"Hobby King"?

"Online Metals"?

 

I can buy a replacement tube from the company, however its in a kit and not cheap, my idea to use carbon fishing rod part is for weight and because its free , as much as I can I want to use found and scrounged parts, for me thats kind of the project.
I am getting some more pics together for some more details. Some of it I am sure some wont agree with, and while I am open to idea's I dont want anybody to be offended if I go my own way on this one,I have a very firm idea of what I want. The radio part and the 'BRAIN' are way way overkill, but alot of fun . Next I will give some details on what I intend to do to the body work!! I am really hoping people like the idea's I have for it.
Some parts like the charger and choosing power packs I am going to need help, alot of the other parts I am ok with.

 

I can buy a replacement tube from the company, however its in a kit and not cheap, my idea to use carbon fishing rod part is for weight and because its free ...
...

Keep in mind that the front/rear balance of the copter will be changed if using a lighter rear spar.

That probably won't matter because you're also adding electronics and changing other mech components anyway.

Nice project!

 

he is driving me mad with it!! but its better than the thing sitting gathering dust in a cupboard

 

Thanks RB, the whole thing is currently way out of balance so its on my list of things to change, the battery pack is fitted as far forward as it will go, this tells me that there is room to improve the balance.
One thing I am lucky with is the fact this thing has alot of unused space inside of it, so moving things about and getting the balance right is a bit easier, I will start to strip the helicopter down once I have done some initial test, I will of course post pics as I go. From the start I intend the helicopter to rely on electronics to keep it level and balanced to some degree, so as long as it isnt too extreme I have alot of leeway with the balance.

Bodywork
My intention is to make several different body types for it, one will be angular like some of the spy planes etc, one will be very rounded and one will be very 'space age' looking.
Although its a totally fun project I would like to at least give it some kind of purpose, I like to do this for all my projects, even if its just a nod at practical. One of the upgrades I saw for it was a camera, these were total rubbish, very heavy and single shot, the quality was also poor. I have what I think is a brilliant idea for two on board camera's that shouldn't weigh very much, but details on this another time.
I am going to make the bodywork from Hieniken (sp?) extra large beer cans! I intend to cut the top and bottom off them and then cut down the middle, the reason's for using this are simple, down the tip is a recycle bin for aluminum cans, someone who goes there regularly always leaves bags and bags of these extra large cans!! They are also very very thin and lite. My method for cutting and joining will be as follows, I can draw or print small sections on paper with a added flap, then I will put two bits together and double bend the flaps so they lock into each other (I will do a picture when I start so its easier to see what I mean), then I will beat flat the seam with a hammer, once I have the sections done I will drill the seams and paint, once painted I am going to use very tiny pop? rivets down the seam, this is more for show than for making it secure.
For cutting out the shapes I have a very cool option, 3 or 4 years ago dad and a friend of his brought a very expensive A3 size CNC machine, it cost thousands!! And has never been turned on let alone used! The project they got it for was cancelled so its never been used, I will get some pics of it later, if I flatten the sheets of aluminum down and stick them to the back of some waste material with double sided tape, I can use solid works and the CNC machine to cut the pattern parts out! This should let me do some very good panels for the helicopter, the cans I have in mind weigh about as much as the plastic that was originally on it.
I am itching to do the body work, I rarely get the chance at School (when I go) to do metal work, so its a chance to get some practice. While I am talking about the CNC machine, I also intend to eventually replace the two main motor gear wheel's, these are currently plastic (I will add pic below), what I am going to do is collect a load of cans and smelt them down in our home brew furnace (its outside and uses wood and charcoal for fuel) there are several holes around the side of it with ceramic 4 inch sewer pipe coming out, the pipe goes into box's and are fed with high blasts of air via some COOKER FANS (this is why I mentioned them in another thread).
We used the same system at our other house, it smelts aluminum and lead really easily, it isnt pretty but works well,then I will cast the gear wheel's in aluminum and clean them up and tweak them on the CNC .
I might even do a couple that are a different size/ratio, I will be careful not to alter it too much though, also if I cast them I can make them thinner and lighter as well as add a couple of slots for use with a IR led for a tacho, infact I can think of a few different things I could do to tweak these gears, and again a great learning tool.
I am aware I need a huge amount of cans, but there seems to be no shortage of empty beer cans . I have also added a pic of a spy plane, it gives you a rough idea of one the body types I am going for.
As I mentioned earlier, I am going to make some modules that do different things, that way I can make the helicopter multi function, it will also give it some practical use. One thing I am really keen on doing is mounting the camera thing, we have a wood on our land and in a couple of huge tree's, there are some bird of prey nest's, I might be able to get high enough to take pics of the nests. Dont worry dad is an expert on birds and he will make sure I do not disturb them.

Next time details on the radio system Hopefully you will really like this! I have some ultra cool stuff for this , I have most the parts already for that, the radio side will be a big change from what it has now , and obviously complete and utter overkill

 

Hey LG,
nice to see the project progressing over here.
With respect to the overall balance of the heli, think where the rest of the airframe is hanging from when it is in flight......
Regards.

 

Hey LG,
nice to see the project progressing over here.
With respect to the overall balance of the heli, think where the rest of the airframe is hanging from when it is in flight......
Regards.

This might seem a little mad, I think those two little bars that stick out might be used for testing the balance, I cant see any reason why they are there.
Also if they are center of the shaft then isnt that where the balance point would be? I know I need to make it ever so slightly off balance in favor of the rear this time, things like balance will be controlled by the electronics, so while say in hover the electronics will keep it stable.
At the moment it dosnt feel well balanced when its flown, but I need to find the controller and rig up one final flight, this way I can take readings so I have a start point. I don't think I will get the chance though, shame as it would have given me some base data and readings, like how much difference in RPM's in the rotors to keep it straight, there has to be a difference because the top rotor has the balance bar, this I am sure gives it more momentum, if that's the case then the bottom one needs to rotate X amount more to keep flight straight. The killer is finding X

I have moved the whole thing over here, no point me going back after that shambles

 

I have moved the whole thing over here, no point me going back after that shambles

This is a gain for AAC!!!!

 

Radio

The radio system I have in mind is 868MHz transceiver built into a 8051 micro, I have a Dev kit for this and 3 or 4 cards for it, I will post specs and some pics later, the frequency is normally used for smart metering, however with the kits I have I get full control over center frequency and number of channels, in fact just about every parameter is accessible. The card unplugs from the dev kit mother board, the kit also has a full range of different antenna's that can be used.
I have run out of pics space so will post another reply

 

CONT
The idea is to use the motherboard to develop the software and then just use the little square card, I can mount this inside the helicopter, and have the antenna sticking out.
The chip will pass the commands to the main control unit, I am thinking SPI for this, the micro inside the chip will collect data independent of the main processor, this is then sent back straight after a receive operation or after a set time, I intend to use a separate channel for it.
One the really nice things is complete control of parameters via software, so I could use low power to send back data, if the ground unit dosnt receive it can ask for a repeat at a slightly higher power, this can continue until it gets the data, I am hoping it will save some power, but I think its 18mA @ 10db, so it isnt that bad anyway.
I will post more details on the radio set up next, the range is approx 3 KM at around 13 db (IIRC) however I think the unit can output 20db max.

 

Because of the size of this project, I intend to build a webpage detailing it all, a kind of blow by blow account .
For those that like detail I have included below the data sheet for the Transceiver 8051 micro. I will start posting (hopefully before end of the weekend) some pictures of experiments with the wireless Dev Kit, I want to do some range testing etc, the dev kit has a LCD so it easy to get info out and on the screen.

 

Easier and better for casting is something that has already been cast, there are many different alloys of aluminium, the alloy in cans is not designed for casting and are coated in plastic and paint. I'm planning to do some in future and have saved an old set of cranks from my bike, probably nearly 0.5kg. Look around, you will probably find something much easier than cans.
<ed> Just looked around, there's a decent amount of aluminium in the casing of a dead hard drive </ed>

 

Good idea for the hard drives, I normally burn the can's first, there is alot of crud that floats when you melt them down that's for sure, I will keep an eye out down the tip for aluminum, I need smallish bits because I cant keep the furnace hot for very long.
I am looking forward to casting the gears and some of the part's, having the CNC is a big help in cleaning it all up after.
I built the bodywork of my robot using cans, they are a great source of metal sheeting for stuff like that, although its very thin I like working with it.

 

I have had a little luck! I came across a TI app note detailing a 9 axis sensor board with direction cosine matrix, I was actually looking into direction cosine matrix for the autonomous flight, the good part is there is some source code for a flight GUI, its written in VB and the input is serial, although I intend to use a different processor, the GUI is a great starting point for when I come to do my own!

 

<ed> Just looked around, there's a decent amount of aluminium in the casing of a dead hard drive </ed>

A question. Are you sure about a hard drive casing being aluminum? Most things like that are die cast zinc. A good source for quality, strong aluminum for casting is a scrap automatic transmission housing or pistons from an engine. They both can be broken into smaller pieces with a sledge hammer if needed.

 

A question. Are you sure about a hard drive casing being aluminum? Most things like that are die cast zinc. A good source for quality, strong aluminum for casting is a scrap automatic transmission housing or pistons from an engine. They both can be broken into smaller pieces with a sledge hammer if needed.

I have some old drives I am sure are aluminum, but I am going to check them all as I have a use for some zinc

 

Good point, I'm not really sure, it should be fairly apparent from the weight. If it's zinc it will feel pretty heavy.

 

Judging by the cost of zinc for sacrificial boat trailer anodes, I would think most modern ones were aluminum, but I will look out for it as I have uses for zinc , handy tip thanks. I didnt think of engine parts, not sure if there is anywhere near here t get some, but would be very handy if I can break it up small, I also want some cast aluminum block's so I can cnc some custom heat sinks.