Introduction: Nano Air Swimmer

Picture of Nano Air Swimmer
With Air Swimmers swarming all over the gadget scene and as a tribute to the original Air Swimmers, I wanted to see just how easy it is to build one myself.

Air Swimmers come cheap, but they are quite large compared to modern RC blimp standards, making them not very manoeuvrable in smaller rooms. So with Plantraco creating a new class of nano blimps I wanted to check how difficult it is to build an air swimmer in the nano blimp class, i.e. based on a 9" latex balloon.

Building a working Nano Air Swimmer proved to be quite simple (keeping it simple being the key). It's all in the tail: everything is done with just one servo. The servo combines propulsion and steering, as in commercial air swimmers.

While commercial air swimmers move their center of gravity back and forth to move up and down, I went for an even further simplification: the nano air swimmer is permanently pointing slightly up and moving forwards means moving up, stopping means moving down (a trick used in 2ch toy blimps).

Check out how it performs in this video:

Note Februari 27th 2012: I corrected a large number of text errors, but there are probably quite a few still. English is not my native language. Please feel free to point out any mistakes.

Step 1: Materials and Tools

Picture of Materials and Tools
Plantraco does not explicitly comment just how small and light their Nanoblimp is. From the "helium + balloon sets" they sell with it, I gather it uses 9" balloons and has a gondola around 6g or less. 6g is the "guaranteed" lift capacity of a fresh 9" latex balloon. So my goal was to keep everything attached to the balloon under 6g.

Used RC gear:
  • An ultra micro receiver under 1g. I used my favourite 0.65g DelTang Rx33 DSM2 receiver. This is the most expensive part at around 30 EUR. With a slightly larger 11" balloon you can use the 2.2g OrangeRx R415 which can be found at 22 EUR to 10 USD, depending on the supplier.
  • An ultra micro servo under 2g (a regular type, not a linear one). I used a so called 1.7 g servo, which actually weighs 1.9g with wires and connector. Make sure the connector is compatible with your receiver. Such a servo goes 12 EUR to 4 USD, depending on the supplier).
  • A 1s LiPo battery around 2g. I used a Zippy 50mAh cell. With a fresh 9" balloon (carrying 8 g) or an 11" balloon I was also able to use a more common 2.5g 80mAh one. Such batteries should cost around 5 EUR or less.  Obviously you will need a suitable charger (not shown).
  • A 25cm battery extension lead to connect your battery to the receiver. A shorter lead works too, but it allows  for less trimming the weight distribution. Specialist suppliers of micro RC gear can make that to order for under 4 EUR.

For the tail:
  • Some EPP sheet (Expanded PolyPropylene), 3 mm thick. I used a triangle with two 16 cm long rectangular sides
  • About 5cm of 0.8 to 1mm diameter carbon rod.

You can get all of te above at aether-sciences.

For assembly and trimming:
  • Some sewing thread.
  • Superglue.
  • Tape (scotch tape or selotape).
  • A couple of grams of putty, to be used as trim ballast.

All this is added to a 9" latex balloon, inflated with helium (and treated with Hi-Float). You can get it at the balloon shop (1-2 EUR for one) or bring home a helium bottle (rented or bought, around 50 EUR for a canister + 50 balloons). Depending on temperature and moisture a latex balloon will last longer or shorter. The spare buoyancy needed for the nano air swimmer lasts roughly a day.

  • A scale accurate to 0.1g
  • A felt tip marker pen
  • Scissors

Step 2: Making the Tail

Picture of Making the Tail
The carbon rod is attached to the servo horn with some sewing thread. After tying down, the thread is soaked in super glue for a stiff attachment. Excess thread and horn ends are cut, to allow for free movement of the horn later on.

The carbon rod is attached to the tail fin with some tape. Align carefully, so the fin will be perpendicular to the servo and fix in place with some drops of superglue where the rod protrudes from the tape.

Experimenting with shaping the tail fin showed it not to be very critical for good propulsion.

Step 3: Attaching to the Balloon

Picture of Attaching to the Balloon

As the servo with the tail represents a large part of the weight, it is attached to the convex "top side" of the balloon (having the largest buoyancy).

Mark the middle of the "top" of the balloon. Tape the servo in place with its axle at the mark.

The servo and battery extension lead are inserted in the receiver and some tape is added to relieve any tension on the wires where they go into the connectors. The ultra micro connectors do not provide much of tension relief, making them rather fragile.

You can choose to put the servo on either the rudder or the aileron channel. Switch on the transmitter and the receiver to check. With the servo in neutral position, put the tail fin on the servo in the middle position. It proved not to be necessary to use the screw to keep the horn on the servo.

With the servo in a straight up position determine the underside of the air swimmer and tape the battery near the lowest position. Let the servo leads - receiver - battery extenson leads "chain" run along the belly of balloon, towards the battery. No switch is used, connecting the battery switches on. The battery lead end is taped to the balloon near the battery, to keep things in place when switched off.

Step 4: Trimming and Flying

Picture of Trimming and Flying

Add putty to trim the buoyancy. The air swimmer should almost float neutrally, just sinking  very slowly. I put the putty on the balloon's knot. Then I move and tape the battery more forwards or backwards till the nose is pointing up just slightly.

The air swimmer should slowly rise when moving forwards with some speed. If not, retrim. In any case a regular retrim will be needed as latex balloons lose helium noticeably in a matter of hours.

Flying is easy, real control takes just a little practice. The nano air swimmer is very suitable for kids and for anyone with a lively inner child. Moving forward is simply done by moving the transmitter's stick left and right with some vigour. Turning is done by restricting the movement of the stick/tail to one side or by keeping the tail to the left or right when coasting.

Obviously the air swimmer is only suitable for indoor use. In large rooms air currents and mainly rising air might prove troublesome, but actually the helium loss of a latex balloon is an advantage whenever it is gets stuck to ceiling.

As long as you keep doors and windows closed and there are no hot surfaces that can damage the balloon, nothing much can go wrong. Even when the balloon does breach the ultra light gear should survive the drop and you can simply replace the balloon and go flying again.

Flight times were easily over 20 minutes with a 80 mAh battery.

Have fun!


masynmachien (author)2016-12-19

I used a so called LP4DSM radio. It's in the first picture of step 1.

With the DelTang Receiver you can use any Spektrum DSM compatible radio.

sevster (author)2016-12-19

curious, what controller are you using here?

prabhat89 (author)2013-02-24

MINIJST-EXT5/9727 Mini Plug Extention for Micro Battery 10cm (5pcs/bag) is just out of stock in hobbyking... What should i used instead of this????????????? plz reply as soon as possible..

masynmachien (author)prabhat892013-02-25

You can use the MOL125M-LEAD/19566 Micro Servo Connector Lead 1.25 Pitch - Male . You can remove the orange wire and pin to save weight. It takes a little more care to plug in the battery correctly, but it works fine and is a lighter solution than the Mini Plug Extention.
When using the OrangeRx R415 receiver, you probably already picked them up together with their counterpart MOL125F-LEAD/19565 Micro Servo Connector Lead 1.25 Pitch - Female Plug (5pcs/bag), to make the extension lead.

Please keep me posted on your project.


Cannonball2134 (author)2012-02-23

Is there any way of reducing the cost of the materials? A 1.7g servo cost about £6, Helium about £25, micro receiver £25, battery £4, few pounds for the other materials, plus a controller if you don’t have one.
That’s roughly £65 + controller. If I wanted to make an army of 10 of these it would cost about £385.

You can reduce the costs by using 11" balloons, carrying 10g. This way you can use a 2.2g OrangeRx R415 receiver for $10, the HK-5320 servo at $3.77 and a 130mAh battery at $1.33, all at HobbyKing. Ordering for 10 at once should limit the delivery costs. Take in account you will pay about 30% import taxes.
cpang1 (author)masynmachien2012-04-04

I am really new to this. How/Where does the battery connect to the receiver if i use the OrangeRx R415, HK-5320 servo, and 130mAh battery? and what lead do i use? Being detailed and specific would really help. I am going to order the parts from HobbyKing.

Thank you very much.

masynmachien (author)cpang12012-04-05
I will try and explain, but if you have no experience in assembling RC projects, I do recommend you get live assistance from someone who does. The HobbyKing parts come without manual and I can hardly start writing a 101 on RC components.
First the shopping list for the version with HobbyKing parts:
From HobbyKing
R415/18827 OrangeRx R415 Spektrum DSM2 Compatible 4Ch Micro 2.4Ghz Receiver
HK-5320/17540 HK-5320 Ultra-Micro Digital Servo 1.7g / 0.05sec / 0.075kg
MINIJST-EXT5/9727 Mini Plug Extention for Micro Battery 10cm (5pcs/bag) SEE ALSO BELOW
N130.1S.25/11857 Turnigy nano-tech 130mah 1S 25~40C Lipo Pack (Kyosho, Eflite, Parkzone Etc)

You could order 1mm diameter carbon rod Carbon Fiber Rod (solid) 1x750mm from HobbyKing or find a 0,7-0,8 mm one in many RC shops.

From other sources:
DSM2 compatible transmitter (make sure your transmitter is DSM2)
3 mm EPP-sheet (at microflight RC shops or you can look for alternatives and test paper sheets of different thicknesses)
Sewing thread
Scotch tape.

 Are you familiar with binding a receiver to a transmitter? The two larger pins on the receiver are for binding, they are NOT a power connection! To bind, connect the large pins electrically (with an alligator clip or a binding plug) and follow the instructions of your transmitter.
Connecting the servo to the receiver is straight forward. If you look at the connectors it is clear you can put them in only one way around. If the servo does not respond to the correct transmitter stick, simply try another socket on the receiver. If left and right are reversed, either do a servo reverse on your transmitter (if this function is available) or simply put the servo upside down on your balloon.
The battery connectors have the same pin spacing as the receiver sockets, but as there are only to contact instead of three you can put them in the wrong way! Check the servo leads to see which pins are the power (the red and brown one). The pin corresponding to the orange “signal” wire is not used for the battery (It might damage the receiver if you do).  So the battery or its extension lead is attached to any receiver socket, keeping to the side corresponding to the power pins an leaving the signal pin alone. The + and – on the battery are normally the right way around. But obviously it is best to check. I read there are some batteries that are assembled the wrong way around. Checking is easiest with the extension leads described below.
You can connect the battery directly to the receiver, but it is much more practical to use extension leads. For the nano air swimmer it is practically mandatory in order to be able to move the battery for a good weight distribution. The lightest solution is a battery extension or servo lead extension made to order (shops specialized in micro flight can do that for you). The cheapest is ordering extension leads from Hobby King. They come at 2$ for a pack of five, but at 0,6 g for each 10 cm they are relatively heavy. You will need 3. With a fresh 11 inch balloon that is just acceptable. A lighter Hobby King solution is using male and female servo extension leads(MOL125M-LEAD/19566 Micro Servo Connector Lead 1.25 Pitch - Male Plug (5pcs/bag) = $1.20 and MOL125F-LEAD Micro Servo Connector Lead 1.25 Pitch - Female Plug (5pcs/bag). But this requires some soldering and insulating work.

Keep me posted!
godbacon (author)2012-02-25

Ok no pins, but fighting fish with magnets on the front that repel the other fish. that could be a fun "nondestructive" "G-rated" good'ole Time... just a thought. another thought is to have a tiny led down by the motor and fly them in a dark room. Hope you find theirs ideas fun.

ilpug (author)godbacon2012-03-01

or, use a slightly large balloon and tear up one of those cheap little laser pointer to be as light as possible, tape it on and fly it in a room filled with fog machine fog. Laser blimp!

godbacon (author)ilpug2012-03-02

Laser Blimp,I like that. hang it from a wire or string and it will swing as the blimp swims.. Light Show.

ilpug (author)godbacon2012-03-02

Wire is kind of optional.

masynmachien (author)godbacon2012-02-26

A LED for flying in a dark room is great idea. Having the LED lighting up the balloon (a small "LED throwie" inside a 11" balloon, or a LED aimed pointing towards a rather transparent balloon) should give a great result.

The magnets, seem difficult to do. Repelling will only work if you have the magnets approach each other in the right path. Putting on more magnets, even tiny ones will put on to much weight. However simply having the balloons themselves bounce from each other is a kind of non destructive "fighting".

March 25th I'm planning on building some nano air swimmers and microblimps with a couple of friends. At that time we will be able to try out such things.

godbacon (author)masynmachien2012-02-26

two led one red one White would be easy to add. one for each direction the motor spins. and it would provide feed back to the person controlling. Would love to see photo if you light them up. a long exposure of the swimmers lit up and flying around could be really interesting too. . Good luck with your build.

masynmachien (author)godbacon2012-02-28


But I'm not sure what you mean with one LED for each direction the motor spins? It's a unmodified servo, so this might complicate things.

jeff721 (author)2012-02-23

Pink balloon+ itty-bitty legs = flying pig?

masynmachien (author)jeff7212012-02-23

Great idea! I would however try out a corkscrew popeller tail instead.

ilpug (author)masynmachien2012-03-01

cut it out of a soda bottle.

jonnyd55 (author)2012-02-18

This is very cool :) how about having two of these, put pins on the front, and commence battle.....I think a pair of air fighting fish would win the toy challenge with ease......if not would still be huge fun :)

tomward (author)jonnyd552012-02-25

What a great idea - I must try this with some kids!

masynmachien (author)tomward2012-02-26

Please keep us posted :-)

Kiteman (author)jonnyd552012-02-18

Better - fill with hydrogen and put a small piece of smouldering wood on the end of the pins!

Nano-shark-blimps with frickin' laser beams on their foreheads?

cammers (author)Kiteman2012-02-19

Now you're talking.

timarnold (author)Kiteman2012-02-18

What could possibly go wrong???

cammers (author)timarnold2012-02-19

Well said.

jonnyd55 (author)Kiteman2012-02-18


masynmachien (author)jonnyd552012-02-18

Hey guys, I wanted it to be a cute little fish :-)

Or actually, I must admit I thought about a "battle version" and learned from some preliminary experiments that a tiny knife edge (like a piece of a small disposable utility knife) works far better than a pin.

jonnyd55 (author)masynmachien2012-02-18

Ok, leave this one as the cute fishie, make angry shark vs furious dolphin editions ......... Then............ Fight to the death! .... Oh and so it doesn't feel left out the cute fish can be the referee or something!

ProCactus (author)2012-02-23

Cool, Im sitting back having a couple, Click your link from an email. This made me laugh pritty hard.
The fish works well.

What about a condom? surly that would give you the best balloon? or maybe it breaths too much. Anyway I cant try this soon, but maybe one of you can?
Fill a condom with helium!

Is there a vote thingy for yours ?

masynmachien (author)ProCactus2012-02-24


Balloons are cheaper and easier to work with than condoms. For the fish I prefer the balloon shape anyway. But I have thought about using a condom for micro blimps. However, I have no idea yet on how long they last inflated with helium and if Hi-Float helps. From the little information I found it looks like helium filled condoms last less long than latex balloons. I should try it one day, but in the meanwhile any more info is indeed welcome.

The vote thinghy sadly never showed up. You can still rate my ible though.

Lord Jon Bigglesworth (author)2012-02-23

Very cool! About how much did it cost for all the servos and whatnot?


I added some information on costs in step 1. Also see my answer to Cannonball2134 below.

The simple DSM2 transmitter I used can often be found second hand for around 20 EUR (from RTF sets).

ac1D (author)2012-02-19

I bought a giant shark air swimmer. The clerk offered to fill it with helium for free.
I accepted! Then I went outside of the store, to put it in my car, and the wind stole my brand new air swimmer.. Fml.

masynmachien (author)ac1D2012-02-23

That is to bad.

When buying a helium filled balloon from the balloon shop, I usually let them attach a ribbon, as they are used to do when selling it to kids. At home I remove the ribbon.

jcksparr0w (author)ac1D2012-02-19

that stinks

snfg (author)2012-02-23

I want to see a whole school of air-fish.

enveslope (author)2012-02-20

Hehe, nice one!
Im into RC building/flying and this fish' gonna amuse my little daughter tonight-)

Thanx :-)

masynmachien (author)enveslope2012-02-21
Thanks. Please keep me posted on your success.
Kiteman (author)2012-02-18

Very nice job.

Do you have to replace the balloon when it goes down, or can you refill it?

balisticjoe (author)Kiteman2012-02-18

I have heard of a way to do an old magic trick where you put a small piece of tape on a balloon, then poke the tape with a needle, and it will only slowly deflate, giving the illusion it did not pop. Maybe if you were to try this, and then re-cover the hole with another piece of tape, you could use a small needle to refill the balloon. I do not know if it will work, but worth the try if you have access to a needle.

masynmachien (author)balisticjoe2012-02-19

Thanks, but using a new balloon and taping the gear to it is much simpler.

masynmachien (author)Kiteman2012-02-18


Refilling a latex balloon is possible, but it is quite tricky and it will probably not last as long as originally. It is much simpler to replace it. Once you have done it once taping on the gear again is quickly done. Trimming needs to be redone in any case.

Kiteman (author)masynmachien2012-02-18


imshanedulong (author)2012-02-18

Where did you get those small servos?

I got it from Aether-Sciences, but there are a number of other online shops specialised in micro RC flight.
mr.incredible (author)2012-02-18

Would a Mylar balloon last longer, and be refillable?

Definitely, yes on both questions. But foil balloons have a higher proper weight. This means that you can not choose them as small as a latex balloon and still have some lift capacity to spare. A 20" inch one would be about the minimum.

Win Guy (author)2012-02-18

I wish I'd seen this Instructable before I asked for an Air Swimmer for my birthday... Oh well, maybe I can still build this and use my Air Swimmer as something off of which to based it! Win Guy

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