Wow, like most other questions on RCU, we got guys using 8 and others using 16....I don't have any planes with rubber bands but I think I went with 8 or 10 years ago. Maybe average it out....8 + 16 = 24 divided by 2 = 12. Nah, just go with 8! LOL By the way, even just a few rubber bands dont give much in a cartwheel, I say modify that thing for wing bolts and don't cartwheel it!