Once the fan was complete, our next step was to connect the fan to the hovercraft and see how it worked. Despite being underpowered for the task it was meant to do, it was capable of moving the hovercraft a bit faster than the leaf blower did on its own. However, it was still painfully slow and only worked on very smooth ground. To increase the performance, our new priority was to reduce friction with the ground as much as possible so as to get the most out of our small motor. We ended up making the hole in the skirt quite a bit larger to reduce the amount of it touching the ground which did make a noticeable improvement to its ability to glide along the surface. Once our modifications were done, we successfully managed to go from completely off, to hovering above the ground and moving forward in a controlled manner while caring a person (though still really slowly).
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Once our hovercraft was fully capable of hovering, the next step was to give it a means of propelling itself forward. Initially, we tried using another leaf blower laid down facing backwards, however the maximum speed that it could reach was well under a walking pace. We determined that a much larger fan would move enough air fast enough to get the hovercraft moving so we took the motor from the leaf blower and began building a fan to place it in. Step one was to mount the motor and propeller (which came from a box fan) to a long piece of wood which would also act as a tiller. Then we built a cage out of two circular pieces of plywood covered in a metal mesh to house the propeller safety. These were then connected together with screws and angle irons. This assembly was then loosely bolted to a vertical PVC pipe where it could be easily turned from side to side, allowing for the hovercraft to be steered. The construction of this fan was largely assisted by Frank Komitsky who generously donated his time, engineering experience, and carpentry skills to ensure that our final product was the best that it could be.
While on our Spring Break, many of our group members were out of town, so we were unable to meet together to work anything physical on the hovercraft. After taking the leaf blower motor out of the leaf blower last week, we are facing the challenge of finding a compatible fan blade that will be able to attach and run efficiently to produce the propulsion we need. With everything else completely ready, we are excited to finally figure out the final fan propulsion situation. We are confident that the plan that we currently have in place will follow through.
After testing a variety of propulsion methods, including literally combining all of the fans that we have, we decided to attempt to remove the motor from our extra leaf blower and use that. After testing with large volumes of air, such as what we need for the lift, we found that we need fast air. The leaf blower motor spins at a rate much faster than all of the fans that we have so far, so the motor, with a slightly larger fan blade, will provide a sufficient amount of fast air to push the leaf blower. To access the leaf blower motor, we worked for about an hour carefully disassembling the blower without permanently damaging the leaf blower structure. After taking out the motor, we were able to take off the blade while still having access to the switch and the power cord. Our next steps will be to find a larger fan blade that will fit on the motor and we will also need to make a mount for the fan.
While retesting different propulsion options for our hovercraft, we noticed a minor issue. The bottom of our skirt, due to repeated wear, had developed multiple rips on the corners of the large ovular air release hole. We figure that this is either due to the large air pressure that is continuously being blown into the skirt or the skidding that occurred during testing without full lift power. To solve this issue, we have placed some small patches around the whole to mend the problem and provide extra support. To prevent this problem from happening again, we will not test the leaf blower without full power because doing so causes damage with little to no reward. Our next steps are to continue testing different propulsion methods.
While continuing our efforts to make the hovercraft self-powered, we have bought a seat that we can fit the battery into. Our original intention was to build a seat out of plywood, however for the purpose of simplicity and to reduce weight, we bought a heavy duty hunters trunk. Using this trunk will greatly reduce our estimated weight because the relatively thin plastic is much lighter than wood. Also, placing the batteries in the trunk will allow for easy storage and flexibility in weight distribution. During our conversation with Lone Star Hovercrafts a few months ago, the owner stressed the ability for us to be able to slightly adjust the weight to maintain balance. Having a mobile battery storage will allow this. Our next steps will be to drill holes in the trunk for the extension cords to run through and to figure out propulsion.
Today was a small victory for the Amphibious Spartan team. We figured out that it was not the power inverter that was failing us, it was the battery. It turns out that the battery was too old and it did not charge correctly. Now, with new spirits, the team headed to Auto Zone on Dairy Ashford and Memorial in order to buy a new battery. We drove to Auto Zone, obtained a battery, then headed back to the project site. We hooked our new battery up to the inverter and completed the rest of our circuit. With high hopes, we counted down 3, 2, 1, on! And the circuit was complete and fully functioning. We each took a ride on the hovercraft and took pictures. We are now about 80% done with the hovercraft, and on to the finals steps!
After much deliberation, we decided not to indulge into the complexities of a steering system comprised of cables and a wheel. This system would take lots of time to create, add additional weight to our hovercraft, and be prone to fault when it comes to reliability. Instead we have decided to put our propulsion on an an outboard system in which you directly turn the fan. This simplifies the overall design and will help immensely when it comes to complete construction of the craft. This means we need a metal rod, pvc pipe, and two thin sheets of metal to construct the outboard system. The pvc will be placed vertically through a hole in a wooden box of our making. We will then put the metal rod, of smaller diameter, into the PVC pipe and attach two very small strips of metal to the rod. Small screws will go through the PVC pipe and catch on the strips of metal to inhibit the rotation of the rod so it can only span 180 degrees. Lastly, we will attach the propulsion system to this motor completing the outboard system.
This week the amphibious spartan team began to think about how we want to seat our pilot. Our plan is to make a seat out of wood right now, but that may change in the future. We know that we will need to use some sort of container in order to store the circuit that will be used to power the hovercraft. We will most likely get a cooler to store our battery, but we are not sure yet and will discuss this later. We must take into consideration the ventilation of the battery because it will heat up, so wherever we decide to store it must have access to airflow.
This week the amphibious spartan team began to assemble the holsters on each side of the hovercraft that will be used to hold the leaf blowers in place. The holster will be constructed out of plastic tubing and screwed into place. The team decided that the holster method is the most effective way to generate lift because the leaf blowers can easily be moved in and out of the holster if needed. The holster method also allows for the air to escape when the leaf blowers are turned off and deflated. In the following weeks and months to come, the team will begin to work on creating the circuit so that the hovercraft does not have to be plugged into the wall. One thing our team did very well during this weeks project was screw in the screws in the right place. Woohoo.
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Authors:Andrew |