Sat Sep 25 19:19:59 2021 GMT
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Q: just how do ns make and attach a parachute to the rocket?
A: A 10-20 inch diameter parachute make from a plastic garbage bag functions well for a 2-liter plastic bottle rocket weighing about 1/4 lb (4ounces).I"ll current instructions for production the parachute below, but first lets talk around some design decisions you need to make.There room a couple of factors you might want come consider prior to designing your parachute:How lot does my rocket weigh?How rough is mine rocket?How high will it fly?How quick is the wind?These factors are crucial to your architecture because they result how quick you"ll desire the rocket to descend under parachute, and also how far down-range itwill go before returning come the ground.For most of us there is limited space because that our restore area (the park, or her backyard).An example:Your rocket is walk to go 200 ft in the waiting (by simulator estimate), that weighs 3.8 onces, and also the wind is blowing in ~ 6 miles every hour.If you have a 30 inch parachute on her rocket it will certainly descend in ~ 2.3 feet every second.The wind is 8.8 feet per second.Your rocket will take trip 765 feet down-range prior to landing.Do you have a ar 800 feet wide?
If you mitigate the dimension of the parachute to 8 inches it will descend at 8.8 feet per second.Then the rocket will certainly land 200 feet down-range indigenous apogee.So, just how do i calculate the ideal size?
The habits of a one parachute is governed by the drag it produces once pulled v the air.The resistance force because of drag is:
Where:Ap = area the the parachuteCd = traction Coefficientρ = thickness of the air (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 calculation the area to administer a given descent velocity for a provided weight(R):
Use this spreadsheet to calculate the suitable size for her parachute.
You are watching: Bottle rocket designs with parachute
Now develop the parachute:
You"ll need: A plastic garbage bag, the thin, dark, variety.Light-weight dragon string."Scotch" or "Invisible" tape, 1/2" wide.3 feet of more heavier nylon string or cord.A special rubber band.Step-by-step:
Cut two seams of the plastic garbage bag to open it into a sheet.Cut a square the the plastic huge enough on every side to incorporate your parachute diameter.Fold the plastic square in half.Fold the plastic again to form a 1/4 square.One corner of the square is the facility of her plastic sheet.All subsequent folds should be at this corner, creating a wedge.Fold the plastic 3 much more times, every time splitting the edge in half.This should kind a wedge of around 11-12 degrees.NOTE: try and do these folds together sharp together you can.These folds will be visible later on to guide the attachments of your shroud lines.Measure the parachute radius indigenous the allude of the wedge and also cut the urgent plastic to type the circular outline of the parachute canopy.NOTE: friend may also cut turn off 1-1.5 inch of the allude to type a 2-3 customs hole in the center of the parachute canopy.A feet in the facility stabilizes a parachute so the it descends without wandering.Unfold the plastic onto a level surface (usually the kitchen table).
Attach 8 shroud lines as follows:Tie a node ~1 inch from the end of the kite string.Use 2 inch of invisible ice to connect the knotted finish of the string to the plastic at 45 level intervals around the edge.Use the wrinkles lines, still visible in the plastic, to overview placement that the string.Press the tape steady onto the plastic.Cut the shroud line size to enhance the diameter the the canopy.
Gather with each other the ends of all 8 shroud lines.Tie one over-hand knot about 3/4 customs from the end.Tie a slip-knot top top one finish of the heavier nylon cable or cord.Tighten this knot over the knotted end of the shroud lines.The parachute is now completed. Check the parachute through a dummy weight tied come the cord.Fold the parachute and also throw it into the wait (outside!).
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Tie the rubber band in the middle of the cord to form a shock absorb using 2 loops about 8-10 inch apart.Attach the totally free end that the cord to her rocket with strapping tape, one of two people at the center of heaviness for heavier rockets or the peak ofthe rocket body under the sleep cone.
for much more information see:Paul Grosse: NSA - nose Separates in ~ ApogeeWikipedia: Drag(back)