To prevent this modern parachutes are very advanced, they include parts to make the canopy stay fully opened and other features to make it fall straight and not move where the air takes. Unfortunately only so much technology can be used with a bin liner, cotton and plastocene but I feel that the following method is suitable for the needs of the experiment.
The Method for making the Parachute
A parachute consists of three main parts, such as the canopy, the ballast and the chords. I will explain the design of the parachute and what has been done.
Firstly I made a circular canopy as I thought it would be the best shape. What influenced my choice is that it was the nearest to the shape of parachutes that real paratroopers use. I decided that if the shape is good enough for paratroopers, it’s good enough for me. The only problem is that on a real life parachute, there are skirts around the edges like on a Hovercraft to hold air in, and maximise air resistance. Unfortunately this was to complex a design to make. The radius of the parachute was 15cm thus giving it an overall area of 225cm2. This appeared a suitably large area for the experiment. The only material available to make the canopy was a bin liner, or a plastic bag as we now call it. This is a thin material but it was suitable for the investigation.
I then used fairly thick cotton string to hold the weight onto the parachute. The length of this string was 17cm. This was set as it was as it looked in the right proportions to the parachute. There were no real scientific ways of making the string the correct length in proportion to the canopy.
Testing and Results
The next step was to test the parachute to make sure it fell to earth in a moderately steady fashion and gain some results to prove my prediction and investigate parachutes.
The test drops were successful without any ballast and the parachute fell to earth or the floor of the science room without drifting very far away from the point of release. One obvious thing that could be observed is that the parachute fell in a spiral indicating that the weight already was not distributed evenly over the four connecting points of the cord to the canopy, or there was a an air current in the science room. This could not be made perfect and the balance was only slightly out and so I left this, as I did not consider this to make much difference to the descent of the parachute.
After the parachute was tested an official plan was laid out. The parachute would be dropped from two meters. This was decided, as it would be a better scale to be plotted on a graph and was a safe height to be dropped from, as there was not much stability in standing on tables in the science room.
I decided that the parachute should be dropped with each weight three times to gain an average as the results would then be more reliable than one off results. After three drops of the parachute 5 grams of plastocene would be added, as this was a large weight in terms of the parachute size to be added. The final weight that the parachute would end up carrying would be 30 grams.
Analysis of Results
The results in the table in the previous page are all different and show a slight pattern but when it is in a graph (graph on next page) a clear trends appears.
Sadly at the time of testing I did not consider dropping the parachute without any ballast so I do not have any times for the parachute with no weight.
By using an average line on the graph the overall picture is revealed, it shows all the research in one rather than looking at lots of lines.
On the average line with the least weight it is obviously going to fall slower than the heavier weights and this was proven on the graph. When the parachute had fifteen grams of ballast it fell very quickly then it slowed down again. It got slower with twenty to twenty five grams and then increased with thirty grams. The best weight for the parachute to hold is either five grams or twenty-five grams. Twenty-five grams is a more realistic weight for the parachute to hold. From these results the weight of the parachute can be multiplied to a man’s weight and then the ratio can be used for the canopy and cord to do the same. The weight can be then tested on a scale model. With this data the parachute can be made to measure any person to provide the ideal descent speed for that person and the safest landing speed.
The results did not fully turn out how I expected them to. I expected that as more and more weight was added the parachute would keep falling at faster speeds. I don’t think the results turned out as I expected there must have been a mistake some were along the line when the results were obtained. I think it was when they were recorded.
Evaluation
Overall the experiment was not a major success, as the results did not seem correct. I do not think that the evidence is very reliable. Looking at how I conducted the experiment I would like to repeat the investigation and be more careful and precise when I obtain results. I would take more care when I record the results and double check each one to make sure that it is correct. The results as a whole were erratic.
There is enough evidence from the results to say that the lighter the ballast on the parachute then the more assurance there is for a smoother journey to ground. I think this would apply to all parachutes.
If I ever repeat this investigation I will defiantly use more than one parachute of the same size and repeat all the tests three times so I gain the average results of three parachutes. With more results the trend of the parachutes becomes more apparent and better points and conclusion be drawn from them.
This investigation was not a success or failure but a stepping-stone into how to plan and do a better investigation next time.
