Parachutes and Projectiles

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by wallacebradway
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Parachutes and Projectiles

Parachutes and Projectiles

Our Issue



Our Parachutes

Our Reccomendation

The class average terminal velocity for the WHO parachute design is 2.071 meters per second. Compare this to the class average for the redesigned parachutes, which is 2.267 meters per second. If WHO wishes for a gentler landing to preserve the relief supplies, the parachutes used now will be of better used even though they lack guidance. If WHO wishes to have guidance and believes the cargo can take a hard landing, using the projectile method will be best method due to the fact that they be able to predict and guide where the cargo will drop. This would be an improvement over the parachute, however the speed of the supplies' landing will not be very controlled.Overall, we recommend that WHO continues to use their parachute design because it is able to bring the relief supplies to a slower terminal velocity and therefore to an more gentle, controlled landing. Even though their parachute does not have very good guidance, the integrity of the supplies may be of more importance than the accuracy of the air drop.

Analyzing Parachutes

As we researched the various designs of parachutes, we decided that some form of polygonal chute should be used as our design since the most popular type, the ram-air, is a rectangle is able to provide more guidance to the falling object because it creates an airfoil that generates lift as it falls. Another shape, the circular shape, is used by NASA to slow objects going at very high speeds. We hoped to combine both of these aspects to provide both the speed reduction and guidance capabilities by using a shape that is a polygon but still somewhat resembles a circle. The parachute that we designed took the form of a hexagon.The first parachute, the design of which was given to us by WHO, was circular in shape. It had an average terminal velocity of 4.7875 meters per second. Compared to the class averages for the terminal velocity of the WHO parachute design (1.956m/s), our WHO parachute had a terminal velocity that, on average, was 2.8315m/s faster than the rest of the class's.The parachute of our design, which is hexagonal in shape, had a terminal velocity of 5.4525 meters per second. This result, when compared to the aformentioned class average of the WHO design, shows that our parachute was not as effective in delivering the supplies at a slower speed.Another group evaluated a parachute using a rectangular design. This design was a parachute that was rectangular in shape. Their average terminal velocity was 2.7175m/s. This is exceedingly better than our terminal velocity. When looking at the average terminal velocity of their design compared to the class average of the WHO parachute, they were still a bit faster but were far closer than our hexagonal design.As for the parachute that we were tasked with designing, it on average had a terminal velocity of 2.0705m/s. The class average for the redesigned parachute terminal velocity was 1.833m/s. This data shows that we were able to slow down our parachute significantly and therefore bring the cargo to a slower stop. However, it was not slower than the class's average terminal velocity which tells us that we did not design the most effective parachute.Overall, we noticed that none of the parachutes were able to land exactly under where they dropped. The parachutes either drifted left or right of the point of release. This is a flaw in the guidance system of the parachutes, meaning that WHO would be unable to make a successful drop from directly over the disaster area.In our data, we were able to identify some possible errors. First, the strings may not have been the same length. When the weights were attached, this could have caused the parachute to not open completely at that specific side. Another possible error that we were able to identify is due to the lighting and the position of things in the hallway where we did our experimentation. The lighting made it very difficult to discern where the weights on the parachute were located which may have adversely effected the calculations for our terminal velocity and acceleration since we could not plot those points in our video analysis.

We were tasked by the World Health to figure out whether or not there is a better design for the parachutes that deliver their relief supplies into places that have been effected by natural disasters. We were also tasked to evaluate whether or not there would be a better way to deliver these supplies to these devastation zones. We were given the design of their basic parachute, which is circular in design, and tasked to evaluate the design and propose our own.

Projectiles are objects that are launched through the air. The only force acting upon projectiles is the force of gravity on the object. There are two parts to projectile motion: horizontal (a constant horizontal velocity) and vertical (a constant vertical acceleration rate). This causes the object to travel in a parabolic arc. If WHO were to use the projectile method of delivery instead of the current parachute method, they would have to do some calculations to make their drops accurate.A plane that is usually used for delivering airdropped supplies is the C-130 Hercules. The U.S. military, when conducting supply drops, will fly these planes at altitudes anywhere between 152 meters and 10668 meters at an average velocity of 170 meters per second. Assuming that the plane is flying at 170 meters per second at an altitude of 5200 meters, here are the following calculations that will allow the supplies to be dropped accurately:Verticaly=.5(g)(t)^25200=.5(9.8)(t)^25200=4.9t^21061.2245=t^232.5764=tIt will take approximately 32.6 seconds for the supplies to reach the ground.HorizontalX=(Vh)(t)X=(170)(32.5764)X=5537.988 metersThe supplies will have traveled approximately 5538 meters from the point where the supplies left the plane.

Projectile Option

Terminal Velocity of Hexagonal Parachute

Terminal Velocity of WHO Parachute

Terminal Velocity of Group 9B's Parachute


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