What is the best material to use to make a parachute float in the air the longest?

1. Have your "parachute" be part helium balloon. 2. Don't make a parachute. Make a kite.

One issue... the design of the chute itself depends on how much weight is hanging from it. If the weight is too little, the chute will not be "stable" and it will tilt over and "spill" it's air. This will also be related to the number and the length of the lines attaching the weight to the chute. If you look at chutes that NASA or the Airforce uses, you might see some designs that will give you some ideas, things like a hole in the center or other shapes. The best thing is to experiment. Any material that is light weight per unit area and is strong enough. Silk is used (and was the material of choice for real military parachutes through WW2). You might be able to find a very light weight fabric material, cotton might work, tissue paper might work but it will tear easily and if it gets wet you're screwed, thin plastic like saran wrap might work but it might be difficult to handle. Use fine thread for the lines. If you use paperclips for weights, adjusting the weight up or down will be easy. You might experiment with hanging weights in more than one position rather than a single weight just in the center. If you want to add structures, a plastic drinking straw is quite strong for it's weight and is easy to cut to different lengths. Good luck, sounds like a fun project.

Silk... Aluminum...

One issue... the design of the chute itself depends on how much weight is hanging from it. If the weight is too little, the chute will not be "stable" and it will tilt over and "spill" it's air. This will also be related to the number and the length of the lines attaching the weight to the chute. If you look at chutes that NASA or the Airforce uses, you might see some designs that will give you some ideas, things like a hole in the center or other shapes. The best thing is to experiment. Any material that is light weight per unit area and is strong enough. Silk is used (and was the material of choice for real military parachutes through WW2). You might be able to find a very light weight fabric material, cotton might work, tissue paper might work but it will tear easily and if it gets wet you're screwed, thin plastic like saran wrap might work but it might be difficult to handle. Use fine thread for the lines. If you use paperclips for weights, adjusting the weight up or down will be easy. You might experiment with hanging weights in more than one position rather than a single weight just in the center. If you want to add structures, a plastic drinking straw is quite strong for it's weight and is easy to cut to different lengths. Good luck, sounds like a fun project.

Silk... Aluminum...