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Sub Micro (Spy) Blimp Building with Hacked Servos

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This Ible describes the build of indoor RC blimp propulsion around 10g, suitable for use with a common 11” latex balloon. With a 14” or larger balloon it has a payload capacity for a miniature camera for living room (or workshop) aerial filming.

Building tiny RC blimps has become very accessible with the ultra micro RC-gear available today at affordable prices. Plantraco’s awesome Nanoblimp, a RTF featherweight dog fighting champion, illustrates that. It is just new on the market and if I see it right it must be under 6g, allowing for the use of a 9” balloon. It follows the line set with Plantraco’s earlier Microblimp, with its gondola at 10-12g. The Ballooncraft micro blimp on the other hand has been on the market for quite a while, but using a 17” balloon (putting it near 30g without payload), that’s has become a heavyweight in the Microblimp League.

Anyway it is always more fun making one yourself. For me the trigger was the market appearance of the wonderful tiny DelTang DSM2 receivers, with a weight of 0.23g or 0.65g including connectors. And hacking sub micro servos makes the rest of the build quite simple.You only need to be willing to work with the tiny gear, keeping the total weight near or under 10 g (situating it between Plantraco’s Microblimp and Nanoblimp). Check it out in this video:



I have been building indoor RC blimps for about 12 years now, and dismantling servos has often been the main source for reversible motor controllers and small motors, mainly for the for the tail rotors. For this project the complete three axis propulsion is based on hacked servos.

The servo circuits do not give a perfect proportional control. Actually the concept makes use of the imperfect on/off working of these circuits. In a servo, gets power as soon as the potentiometer is not in the desired position corresponding to the transmitter’s stick position (for some more "theory of operation" on servos check here). But the analogue circuits in ordinary servos do not give full power when the deviation is small. The ones in digital servos do, so these are not suitable for this hack.

As people building tiny RC stuff know, at this scale wiring and connectors become important in the weight. But for this Ible I kept things basic,holding on to the connectors and avoiding soldering. In general soldering is not difficult, but at this scale it does need some experience and the right gear. Obviously this means there is some room for further weight loss, and in step 7 I list some tips for more experienced builders.

You can fly your blimp around in at home and if you have two you can go for a "Plantraco style dogfight" attaching a short pin on the front of each balloon.

Or you can go for a payload version and add a miniature camera. With a large enough balloon a wireless camera is possible, but I kept to a miniature recording camera giving a total weight for camera + propulsion of about 20 g (see last step). Here is a video of the camera version:



If you like this Ible, please don’t forget to give it your vote. Many thanks for your attention!
 
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35Timmy10 months ago

did u actually own the interlectual property of this project because I found the indentical project on popsci source

http://www.popsci.com/diy/article/2012-06/remote-control-airship-instructions-and-parts

please excuse my grammer also I just wanted you to be aware of it because otherwise it could count as infridgement and therefore liable I am not from that sight I am just making sure your aware

masynmachien (author)  35Timmy10 months ago
The popular science article is based on my instructable an was made with my collaboration.
Sadly enough they didn't mention Instructables in the article, even though I asked them to.
billythe811 months ago
they sell stuff like this but not nearly as cool!
fatdumpa1 year ago
hi there. what would the total cost of parts be including the gas?
masynmachien (author)  fatdumpa1 year ago
No. One fill, lastig about a day (8 hours), will be 1 to 2 EUR in a ballon shop. This cost goes down very much depending on the cannister you buy of rent.
slim13571 year ago
Confirmed, the analog servo provides a better proportional response by a long shot.
slim13571 year ago
(for some reason the captcha isn't working properly and I cannot reply to your reply)
I didn't shoot any video as I was running late this morning but I did put a prop on it and put a lot (90%) expo on the channel controlling the servo motor. I did get what seemed to be a proportional response. I am going to setup a little test rig with strips of paper to see how much wind is blowing in either direction at different stick positions. It seems to be more proportional one way than the other. I also plan to pull apart a hxt500 analog servo and see what that gets me. My friend who asked if I could make a "mini blimp that poops coupons" for her show is very excited. I think my step-daughters are going to like it too. I might have to make a bunch of these and have battles.
slim13571 year ago
Hi there, I am building this sub micro spy blimp and I was slightly confused by what you are saying about digital servos. I have already hacked one digital servo and I am using a computer radio so I can center it with subtrim as getting the pot perfectly centered has been difficult. If I understand you correctly, I will get better proportional control by using analog servos? With the ability to set exponential curves I think I might be able to get a more proportional response from the digital servo but I haven't tried it yet. Have you? Thanks.
masynmachien (author)  slim13571 year ago
You got it right.

I once hacked a chinese servo that was supposed to be digital. It actually showed such a clear proportional response, I doubt it really was digital.

It's certainly worth a try. As you've already hacked one, mount a prop and see what it gives, just holding it. keep me posted.

IX Smith XI2 years ago
Do you know why there is a loss of heilum after the balloon has been filled for a while?
masynmachien (author)  IX Smith XI2 years ago
Because helium is a very small molecule and the balloon material is thin, it diffuses through.
gr8...!!! but i have a question though it is not related to the blimp but can u tell me how can i simply run my micro servo??? without arduino or something else......just with a batttery or little modification....??????
Thanks!

What do you want your servo to do? Just run continuously in one direction? Run it from one direction to another or have it make controlled movements as a servo originally does (but without an RC receiver I suppose)?
yup...i want to run it continuously from one direction to another ..........and i also want to know that how can i make controlled movements without an RC receiver ??

thank u
Ok, you will have to choose: if you hack the servo for continuous running, it will no longer be able to make controlled movements, as the hack means disabling the feedback, which is the basis for the controlled movement. Start learning more on servo's here.

To make controlled movements without a receiver or Arduino, you will need a so called servo tester. You can buy one ready made, build it from a kit or build it from scratch like this simple one.

Hacking a micro servo for continuous rotation, is done just the same way as for standard servo's. This is just one of many descriptions available. Many hacks, like the one mentioned above are meant for use with a receiver, an Arduino or a servo tester. If you want to run it without, you need to remove all electronics and connect directly to the motor. Like this. With this option changing the direction of rotation is done by reversing the polarity, for example with a switch wired like this.

I hope this gets you started.

Succes!
TheGreatO2 years ago
Great instructable! I'm slightly confused though, which is probably due to my lack of knowledge about servos, when hacking the servo, do you literally just take out all the gears so that you're left with the motor and potentiometer, and then attach the input to the servo to the throttle output of the receiver, adjusting the potentiometer to get the trim right?
Thanks
masynmachien (author)  TheGreatO2 years ago
Thanks!

You're close. Indeed, you take out all the gears and keep the motor and the potentiometer AND the servo electronics. The latter serves as reversible throttle output (with the potentiometer determining the middle zero throttle point). The servo's original lead is attached to any channel output of the receiver, just as a normal servo.

Some receivers have built in speed control, which you could call a direct throttle output. That is not used in this concept. It is used in the alternative shown in step 7, but then a motor (possibly also from a servo, but without the potentiometer and without the electronics) is connected to that output directly.
Ah! thus eliminating the need for ESC, that is simply genius :)
lukeD2 years ago
is there a way to use NO helium?
masynmachien (author)  lukeD2 years ago
No, for a blimp, or any airship, there isn't. An airship is based on buoyancy (by definition), so you need a gas that is a lot lighter than air, and for safety it should be non-flamable. Only helium fulfills both requirements.

One can build airplanes or helicopters suitable for flying at home, in your living room, but that is something quite different.
another way to lose some of the weight is to replace all the wires with enamel coated speaker wire, like the stuff they use in headphones .
really liked this instructable! keep up the great work.
masynmachien (author)  rocketman2173 years ago
Thanks!

Indeed, once you start soldering, enamel coated wire is the way to go.
Awesome work! thanks for the great pics!
Heliosphan3 years ago
Hi
Im intrigued about the filming aspect of it, so I went looking for a vid on YT of that camera - http://www.youtube.com/watch?v=HEupsuwdFQo
This quality isn't half bad, and only has poor panning performance due to not being able to encode the rapid image changes, or no able to write to the memory card quick enough.
Are you seeing this quality, because I wouldn't be at all disappointed to see that quality in something costing a tenner!
masynmachien (author)  Heliosphan3 years ago
Hi,

I'm still not sure about water on the camera component itself. Will its lens and packaging protect the sensor? It could very well be, but I wouldn't be surprised if water gets in by some capillary effect. It should be dust tight, but not necessarily waterproof. What do you think?

masynmachien (author)  Heliosphan3 years ago
I added a video of the "Spy Camera Blimp" version, including some of the better footage from the 808 camera. My impression is, the motion blur is less in bright daylight, but quite severe under artificial light (as I used).

But indeed, at this price...
Hi
I actually bought one of the 808 cameras since your recommendation, thinking for the future as I want to build an RC blimp too.
I have to say, the footage from my camera is about as good as some of the YT vids make out.
Looking at the footage from your camera, I'd have to say your footage doesn't look as good as mine. The image quality is about the same, but yours appears to be recording at a much lower Frames Per Second rate.
It could be the camera itself, or it could be a very slow memory card.
I bought mine off Ebay for £11, and I chose an auction that came also with a 4GB card bundled!
Dare I suggest it, but you might want to look at buying another of the 808 cams, or at least changing over the uSD card.
The footage is definitely lacking in the fine detail areas of the footage, but I really couldn't be much happier with it for the price.
I'm also thinking of getting hold of the slightly costlier genuine 720p models, which look really impressive for the price.
...
Is there any news on your wide angle lens yet? The angle on mine is quite limiting I have to say.
masynmachien (author)  Heliosphan3 years ago
Hi Heliospan,

In the meantime the lens arrived. I will test it soon.

Following your recommendations, I checked the micro SD card and although it is a class 6 (good sequential writing speed), it has a pretty low random writing speed.
So I will try and pick up a better micro SD card and do some tests.

Thanks for the input!
masynmachien (author)  masynmachien3 years ago
I did a quick test with the jelly lens. It widens the angle with about 25-30% (rough estimate). Far from spectacular, but it brings the view angle in a more "normal" range, instead of very narrow. The distortion seems limited.

When looking through with the naked eye I wouldn't call what I see a spectacular fish eye effect either. The distortion is more obvious at the edges.

With cap, string, jelly ring removed and eyelet cut off, it weighs 2.1 g. Maybe I can remove some more plastic.
Thats great though,
Whatever increase in viewing angle you can get, the better.
Can you let us know where you got this 'jelly lens' from?
I was thinking actually what if you put a small bulbous drop of water on the basic lens? I will get round to trying that myself probably tomorrow. Of course its not a very permanent or resilient solution, its worth a try and the surface tension might last for one whole flight.
.
For your info, the ebay seller bundled in the uSD card, its a non-branded ebay job, marked at class 4. But is clearly sufficient.
Whilst more expensive, its always worth going for a well branded card such as a sandisk. If the price gets a bit silly, perhaps its worth upgrading to a true 720p 808 keyfob camera! :-)
masynmachien (author)  Heliosphan3 years ago
Fascinating idea, using a drop of water! I gues it will be easiest with the camera facing down. Vibrations from the propulsion might make the drop run down when the camera is not facing down.

Do you plan for any protection of the camera from water?
masynmachien (author)  masynmachien3 years ago
Oh, and I bought the lens from a Chinese eBay seller "betterdeals255". It's described as a Jelly Lens Wide Angle Fish Eye For Compact Digital Camera iPhone CellPhone.
*Follow up*
Hi
I just tried the drop of water approach, no real joy.
I used a very sharp implement and let a tap drip onto the end until a drop was suspended, then guided it into the lens opening. Tried this three times.
The first and second attempts resulted in totally blurred video, I had managed to smear the water all around the lens casing.
The third attempt resulted in a perfect dome of water protruding from the lens casing, It gave the video a well focused image, but it wasn't at all 'fisheyed' or wider at all, and it had the side effect of weird lighting anomalies entering the lens. I think part of the problem is that the lens is slightly recessed into the lens casing, making it difficult to get water right onto all the glass.
I also accidentally let a load of water into the keyfob casing, some of it got onto the circuit board, I dried it off, and its still working fine.
By the way, a simple dab with a piece of kitchen roll cleared the water from the lens completely, the quality has returned to normal, dare I say it, a little better!
Oh well, perhaps you might get better luck, its all down to getting the water to completely cover the lens glass, and make an almost perfectly round dome of water protrude, I got the dome, but it clearly didn't get to all the glass.
Thanks for the lens info. I'll look them up!
Yeah there could be an issue with the vibration.
But ultimately we're talking about only micro-litres of water, so it would be nearly impossible to short circuit any part of a modern production PCB.
The boards are designed with multiple layers of material, one of which is that green protection layer. Sure enough there are bare metal solder areas, but drops of water would have to miraculously bridge a connection between two of these spots to *potentially* cause an issue - but remember also that electricity always takes the easiest path, and an intact PCB offers the electrons a far better path to follow than through water with a relatively higher resistance.
Still I admit all this is theory only! ;-)
If you're concerned about it, I would imagine a small amount of clingfilm sandwich wrap, surrounding the camera PCB, would suffice.
.
Today I've bought myself some small props, and some 175mAH LIPO batteries from a nearby helicopter shop! My blimp build is nearly in progress! ;-)
One other thing, my footage also appears to have better FPS than your footage even in lower lighting conditions. So I'd rule that out as a factor.
meenzal3 years ago
Pretty cute. I made one of these with the working gear from a Vapor micro RC plane after too many crashes. Pretty much just strapping the wingless airplane stick frame upside down to a balloon. Yours is more maneuverable though, and with on board video besides! Kudos!
masynmachien (author)  meenzal3 years ago
Thanks!

If you wish, you could get almost the same concept as mine if you take the servo motors out of the receiver unit and fit them with propellors. You will need to solder longer leads, at least to the tail motor though.
Yeah, good idea. I was also giving thought to using a lightweight Sharp IR range sensor with an Arduino pro mini and making it autonomous. I would probably need a bigger envelope than the single party balloons I use. As it is I'm inflating the balloons almost to breaking in order to get neutral bouyancy. :-(

Yours is definitely the best method. Very, very clever!
sitearm3 years ago
@masynmachien;Sweet! I love the Blimp camera view. Not only do the blimps work, you are expert at controlling them.

Cheers!
Site
masynmachien (author)  sitearm3 years ago
Thanks!

The control is made quite easy by adding the tail fin.
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