- 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
- 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).