When a challenge is set to make something big or small (Mikeasaurus' This Month's Challenge: Big and Small) it is obvious for me to go for something small, as I love things tiny. And as there is one thing I tend to build smaller than most others, I went for the smallest RC airship ever. The idea of building a really tiny RC blimp had been lingering in my mind, but now a deadline was set. Obviously I also entered this Ible in the Remote Control Contest
As volume - and therefore buoyancy - decrease to the third power, building a small airship means achieving extremely low mass. This starts with superlight propulsion and controls. For my sub micro blimp I built propulsion and controls amounting to about 10g and for my nano air swimmer this was 6g. In this project I got it to 1.7g for the version without fin. I'm actually curious if the result really is world's smallest RC airship. If you happen to know of any smaller RC airship, please let me know. At least I wanted to share how I approached the build and exchange ideas on small blimp projects.
Check this short video on the blimp flying in different configurations:
After an overview of gear and materials used, I refer to an inspiring thread in Step 2. As finding the smallest, or rather lightest, RC gear was the first challenge, I built up this Ible's steps around each of the different components, discussing their selection and use. This way you can not only learn how I built the blimp, but also how I made the choices and came to a configuration with one main thruster for moving forwards and upwards at the same time, in combination with a tail rotor.
Building and testing was spread over a couple of days, but it could be done in within one day. The build requires handling tiny parts and trimming off weight by less than a tenth of a gram. For me the hardest part was the precision soldering under a magnifying glass. However, in each step I did not only add tips for some further weight reductions, but also options for a slightly heavier, but more "plug-and-play" alternative.
Obviously this blimp is strictly for indoor use only. It is quite forgiving when flying. Even if you hit an obstacle or a draft sends it off, you can just keep flying afterwards. If you do pop the balloon, the light gear should survive the drop to the floor (It did in my case).
Many thanks for the votes.
Note: English is not my native language and feel free to point out any errors or strange word uses.
Step 1: Gear, Materials and Tools
But here is summary list with recommended parts (and the alternatives I used)
- a DelTang ultra micro receiver for low resistance actuators like a Rx51-M (I used a Rx43-D)
- any DSM2 compatible transmitter like a so called lp4dsm2 transmitter (I used a DX5e transmitter)
- a 10mAh 1s LiPo battery (I also used a 8mAh one, barely lighter)
- connectors to connect the battery to the receiver: with the Rx51-M you need a 5mm bahoma-connector (I used male and female lightweight Molex 1.25 pitch battery connectors with leads
- a charger capable of charging at 10mA (this will also work for the 8mAh battery)
- 2 0.3g DC motors
- 2 Plantraco 32mm “butterfly” propellers
- about 60 cm of 0.1 mm diameter enamel wire
As I already had the transmitter and a charger for the battery, the cost of the gear used about 90 EUR.
Further materials are:
- a latex balloon with a net lift capacity of 2g or more
- some Hi-Float to treat the balloon for longer helium retention
- some helium (about 5l)
- a couple of grams of putty as ballast.
- some cellophane tape (sellotape, scotch tape),
- 6.5 cm of 0.5 mm diameter carbon rod
- for the optional stabilizer fin: another 15 cm of 0.5 mm diameter carbon rod and some light paper or foil (the lightest you can get) and non-stick (baking) paper.
The tools used are:
- sharp scissors
- a precision soldering iron
- a magnifying glass, e.g. on a "third hand" soldering aid
- cutting pliers
- a scale, accurate to 0.1g or better, comes in handy