[nynor]

Originally Posted by RPKESQ

Refrigerate your rubber bands in an airtight container. They do deteriorate quickly. Use a dry lube on them just before use.

See if the rubber bands will allow doubling without any stretch. If so, do it.

Is the propeller plastic? If so use heat to alter the pitch so that max rpm is reached at 50% of the distance to be covered.

Smallest cross section, lightest weight possible. No extra drag caused by protrusions.

Can you lube the wire it travels on? A ceramic bearing in the guide tube will minimize friction.

i've done this race, back in the day. the bolded idea sounds like it has the most promise to me.