One of the themes in my RC Blimp projects is building them smaller and smaller. First, because I like small things, but also to save on helium.

However, using lightweight RC gear usually raises the build cost. So in this project, I explored hacking a cheap toy RC car (scale 1/64) for the RC gear. It turned out to be fairly simple. One thing was less so: dealing with the very thin gauge copper wire these micro cars use for their magnetic steering actuator. However, for a workshop, I worked out at easier alternative, as shown in the last step.

The cheapest version uses an 11” latex balloon (a common party balloon), well inflated with helium to carry about 10g. The propellers are very simple and made from scratch (See step 5).

The result is small blimp that is suitable to fly at home or in somewhat larger halls. It can even fight some minor air drafts, but as for any small blimp, forget about flying outdoors.

The weight of the blimp is trimmed till it sinks slowly when no power is applied. The main motor pushes it forwards and upwards simultaneously. Dosing the forwards command allows flying at more or less the same level. Steering left and right is done with a tail motor. The controls on these cheap and tiny RC cars is on-off, not proportional. But actually that works better for the blimp than for the cars, as with the blimp you can use its inertia to your advantage.

Flight times easily exceed the driving time of the original Mini Racer used, reaching over 15 minutes.

Here is a video of the blimp flying:

Step 1: Parts, Tools and Supplies

  • a “Mini Racer” ($8.50 at DealExtreme or even under that)
  • 2 AA alkaline batteries (The cheapest source in Belgium is IKEA at €2.00 for 10, that is less than $0.60 for  the 2 you need)
  • a 0.5g “pager” motor (under $1.75 as in $5.20 for three at DealExtreme)
  • an 11” latex balloon treated with Hi-Float and inflated with helium (a balloon shop will take care of that for you, for under 2$).
  • some thin plastic sheet like from a butter cup (recycled)
  • Selotape/Scotch Tape, (a couple of cents worth)
  • a piece of bamboo or wood skewer (recycled)
  • a little non hardening clay to trim the weight of the blimp (or other easy to dose weights in the range of 0.1 -  3g)
Tools and supplies
  • a PH0 or PH00 screwdriver to open up the Mini Racer
  • a soldering iron and solder for electronics works.
  • some nail polish remover or a similar solvent (or, for the alternative explained in the last step, 2 x 50 cm of the thinnest gauge wire you can find, e.g. recycled from a discarded  mouse/USB cable)
  • a drop of superglue
  • a pin
  • a sharp hobby knife
  • scissors
  • a hammer
Depending on your sourcing the totally cost can vary, but as shown, it can be kept under $13. DealExtreme offers free shipping if you're willing to wait a couple of weeks. You can probably find the cars and pager motors at faster sources for still very low prices. In Europe you can get those tiny RC cars for at Conrad for €11 (and sometimes lessat special offers). Suitable pager motors can be found at Pollin for only €1.25, but removing the eccentric weight is harder.

Make sure the balloon is well inflated to 10 - 11” inch. Usually latex balloons are not fully inflated to their nominal size, to minimize the risk of them bursting during transport, like in a hot car. But if you take care on your trip home, you should be OK. The balloon should be inflated to carry 9g at least and some lift capacity to spare will keep you flying longer. In high altitude area’s you will need a larger balloon, try a 12” or larger one.

As said, you can get a prepped and helium inflated balloon at the balloon shop, but you can also rent a helium tank or buy a one-way canister. When using a one-way helium canister, take in account the helium sold in those is less pure (typically +- 85 %), diminishing the lift capacity accordingly. It still works but you will need a good 11” diameter. Pre-inflating with air (and emptying the balloon again) really helps to achieve a large enough size. Also buying some Hi-Float is worthwhile. The balloon will lose its spare lift capacity of a couple of grams in a matter of hours, a day at the most, but without a Hi-Float treatment those times will easily be halved. A longer lasting, but more expensive alternative is using foil balloons (also shown in the last but one step).
<p>I made it! It has an interesting steering system in that it has both props in the centre.</p><p>The steering rotor is just an inch in front of the main rotor. It still turns but I can also go sideways and Straight up and down. Also I stacked two balloons on each other.</p>
Cool! Did you click the &quot;I made i button&quot;?<br>Thanks for sharing your experience with the alternative configuration. Can you post pictures?
<p>Any balloon with a lift capacity of about 15g is suitable. a bit more is better</p><p> Do you have balloon shops in your area?</p><p>If they do not have the balloon you want, they could order it for you, or they can inflate the balloon you've ordered online yourself.</p>
<p>I have most of the components but I don't have the baloon.</p><p>I can't find a good foil one anywhere!!!!!!!</p><p>Can someone please help me out?</p>
<p>We got a little crazy with the complexity and cost (and danger level) with our blimps (http://www.instructables.com/id/Battle-Blimps). I love how simple, easy, and low-cost your blimp is!</p>
THAT IS AWESOME!!! The future holds awesomeness!
Sweet! I still have 2 of those rc cars lying around. The future holds some blimp races in the office :D
<p>Thanks for posting this very thorough. next time i see a cheep rc car ill probably make one.</p>
<p>Although you mention a pager motor in the parts list, I don't see it mentioned/used further on. Am I missing something?</p>
<p>The &quot;pager&quot; motor becomes the tail motor in step 4.</p>
Thank you! <br>It brings me great pleasure to read my Ible engaged you to build a blimp too. <br>Also thanks for sharing the hints. Paperclips are indeed a very suitable alternative to the non hardening clay to trim the buoyancy .
Thank you for such an engaging instructable--it brought many hours of happy tinkering and experimenting. A couple things that really helped mine: a little $2 propeller from a local hobby shop(as you suggested), a little loop on the belly of the balloon to hang paper clips from: as the balloon loses helium these can be unhooked one at a time--a nice way to gauge remaining flight time. I took mine to a college reunion and floated it over the dance floor to much approval from the dancers.
Thanks for the great project! I'm still struggling to get mine off the ground. I started with one star-shaped foil balloon filled with helium, volume about 14 liters. When it failed to lift the parts off the ground, I added a second, which also failed to provide enough lift. So I checked to see how many US pennies it would lift: just three, about 8 grams. When I calculate lift based on a density for He of 0.1785 g/L I find that my two balloons should be able to lift almost 30 grams. Any ideas? Does Belgium have super rich He? Is our He being thinned?
oops...brilliant wife informs me that mylar balloons are that heavy. And now I notice your foil balloon is almost a meter long.
Indeed foil balloons (it actually isn't mylar) are rather heavy. You can check the helium chart from Qualatex (just google) to get an idea.<br>As surface varies with the power of 2 and volume with the power of 3, the bigger, the easier it gets to achieve enough lift. But with the low power here, keep it under a meter.<br>And sometimes the helium is less pure (typically in those one way canisters).
When I was making mine the back motor wouldn't work any suggestions?
Make sure it is well charched with good batteries in the transmitter. In the meanwhile, i learned the back motor quits first on a low battery.<br><br>I would first remove the propeller t see if it doesn't hamper the shaft's movement.<br><br>if it doesn't help, test the voltage on the leads to the motor (I guess you know how to do that). You should measure a voltage when givving a &quot;turn right&quot; command and an opposite voltage when giving a &quot;turn left&quot; command.<br><br>If you have something about 0.6 or more, then the connections are good up to that point and you should check al further connections. Check if the motor runs if you apply like 1.5V to it directly (e.g. from a battery). These tiny motors can be broken.<br><br>If you can not measure a voltage ever, male sure that were you soldered you did get to the copper (Do you have experience soldering that kind of wire). The invisable insulating layer should break down with heat, but maybe it did not. You can help establishing contact by sanding the wire ends.<br><br>Check the wires to see that they are not broken, but also if they are not short circuited. Don't rely on the invisible insulating wire, it can be damaged.<br><br>Making sure there is no short cicuit, measure the vultage on the solder points on the board, where the thin copper wires start. If you do not get any voltage respond to the commands, the board can be damaged. But those boards are quite robust.<br><br>Let me know when en how you got it to work. If it doesn't send me some detailed photos.<br><br>Succes,<br><br>Yvon
You can meet fantastic crazy geniuses only on instructables !!! <br> <br>Thank you for posting &hellip;&nbsp; <br> <br>(please give more !) <br> <br>you made my day !
Thank you! <br> <br>You can get such super nice comments only on Instructables!!! <br> <br>You too, you made my day! <br> <br>It certainly helps keeping up the work.
you mentioned building an airplane with these electronics, can you direct me to the plans for it?
It is the same link as mentionned in Step 2: http://www.rc-cam.com/microszr.htm <br>I will add it when I talking about the actuator too.
Masyn thank you so much holy cow! You are so great!
CUTE! love the idea how cool woul it be for like hundreds of these things in a hall XD
Decided I'd give this a try today. My plan was more of a zeppelin/airplane hybrid, but definitely in the spirit of the idea. I learned a couple things:<br> <br> 1. Check the battery size of the RC car in question <em>before</em> buying. My car took 3 AA batteries, so there's no chance it's going anywhere.<br> 2. Don't solder in your room of your apartment without first opening a window. Presently airing out my room.<br> 3. Always have spare wire around, whether you think you need it or not. My battery setup is using duct tape and the terminal wire (the springy stuff used to hold the batteries in place).<br> <br> While getting this to fly is likely going to be unsuccessful, I still had 15$ worth of fun trying this out! Thank you for posting!
awesome idea! I wonder what other ideas you can come up with using those motors..
Wonderful hack! I'm gonna make my first blimp with this one this winter :-)
Thanks! Go for it and keep me posted.
I have been meaning to try this for years! <br> <br>Great work - not only did you actually do what I have been meaning to get around to, but you did a much better job than was ever likely to! Lovely job.
Very cool job. I never would have thought to use those tiny race cars for something like this. Thumbs up!
CAT5 cable works well for things like this and it comes pretwisted

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