Fri Oct 22 01:50:11 2021 GMT

Q: just how do ns make and also attach a parachute to the rocket?

A: A 10-20 customs diameter parachute do from a plastic garbage bag functions well because that a 2-liter plastic bottle rocket weighing around 1/4 lb (4ounces).I"ll existing instructions for manufacturing the parachute below, but an initial lets talk about some design decisions you must make.There room a couple of factors you might want to consider prior to designing her parachute:How lot does mine rocket weigh?How rough is my rocket?How high will certainly it fly?How fast is the wind?These factors are crucial to your style because they result how rapid you"ll want the rocket come descend under parachute, and how far down-range itwill go before returning to the ground.For many of us there is limited space because that our recovery area (the park, or her backyard).An example:Your rocket is walking to go 200 ft in the air (by simulator estimate), that weighs 3.8 onces, and the wind is blowing at 6 miles every hour.If you have actually a 30 inch parachute on her rocket it will certainly descend at 2.3 feet every second.The wind is 8.8 feet per second.Your rocket will travel 765 feet down-range prior to landing.Do you have actually a field 800 feet wide?

If you mitigate the size of the parachute come 8 inch it will certainly descend at 8.8 feet every second.Then the rocket will land 200 feet down-range indigenous apogee.So, exactly how do ns calculate the best size?

The behavior of a one parachute is administer by the drag it produces as soon as pulled through the air.The resistance force because of drag is:

Where:Ap = area the the parachuteCd = traction Coefficientρ = thickness of the wait (Rho)V = descent velocityUsing a tiny algebra we can rearrange this into other forms:To calculation Velocity because that a provided weight(R) and also diameter:

or to calculate the area to administer a provided descent velocity because that a given weight(R):

You are watching: Water bottle rockets parachute

Now construct the parachute:

You"ll need: A plastic rubbish bag, the thin, dark, variety.Light-weight dragon string."Scotch" or "Invisible" tape, 1/2" wide.3 feet of heavier nylon string or cord.A special rubber band.Step-by-step:

Cut two seams the the plastic rubbish bag to open it into a sheet.Cut a square that the plastic large enough on each side to encompass your parachute diameter.Fold the plastic square in half.Fold the plastic again to kind a 1/4 square.One edge of the square is the center of your plastic sheet.All subsequent folds need to be at this corner, developing a wedge.Fold the plastic 3 more times, each time dividing the angle in half.This should form a wedge of around 11-12 degrees.NOTE: shot and make these folds as sharp together you can.These folds will certainly be visible later to overview the attachments of your shroud lines.Measure the parachute radius indigenous the point of the wedge and cut the folded plastic to kind the circular summary of the parachute canopy.NOTE: friend may likewise cut off 1-1.5 inch of the point to form a 2-3 inch hole in the facility of the parachute canopy.A hole in the facility stabilizes a parachute so that it descends without wandering.

Unfold the plastic top top a level surface (usually the kitchen table).
Attach 8 shroud lines together follows:Tie a knot ~1 inch from the end of the kite string.Use 2 inches of invisible tape to affix the knotted finish of the string to the plastic at 45 level intervals approximately the edge.Use the fold lines, still clearly shows in the plastic, to guide placement that the string.Press the tape firmly onto the plastic.Cut the shroud line length to enhance the diameter that the canopy.
Gather with each other the ends of every 8 shroud lines.Tie an over-hand knot around 3/4 inch from the end.Tie a slip-knot top top one finish of the heavier nylon string or cord.Tighten this node over the knotted end of the shroud lines.The parachute is currently completed. Check the parachute through a dummy weight tied come the cord.Fold the parachute and also throw it into the air (outside!).

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Tie the rubber tape in the middle of the cord to type a shock absorb using 2 loops around 8-10 customs apart.Attach the complimentary end that the cord to her rocket with strapping tape, one of two people at the facility of heaviness for heavier rockets or the peak ofthe rocket human body under the sleep cone.

for much more information see:Paul Grosse: NSA - nose Separates at ApogeeWikipedia: Drag(back)