Bungee tension is tested at 300% elongation and may vary up to 20% depending on temperature, age, etc. A general rule of thumb for high start launching: Rubber Pull = 5 X Model weight. A "floater" can get by with less pull and a fast composite plane can usually take more.
The following can be use as a guideline:
2m. rubber 1/8"ID x 1/16" Wall - 6 lbs of tension.
2m Comp. rubber 1/8"ID x 3/32" Wall - 8 to 10 lbs of tension.
3m rubber 1/8"ID x 1/8" Wall - 14 To 18 lbs of tension
Unlimited rubber 1/8"ID x 5/32" Wall - 20 To 24 lbs of tension
Standard Bungee 1/4"ID x 1/8" Wall - 28 To 35 lbs of tension
Mega Bungee 1/4" ID x 3/16" Wall - 35 To 50 lbs of tension
Insane Mega Bungee 1/4" ID x 1/4" Wall - 50 To 80 lbs of tension
All Bungees come with connectors installed and a ring on each end. The extra ring can be used as a launch ring.
Hose Monster Rubber Specs
Aerofoam UAV Systems