Testing/Results | Devon Tandberg

Introduction (What will be tested)

The tow bar will be tested in two main areas. The first will be the size and weight of the device. It must be able to be taken apart and fit inside of the Tandberg families Cessna 175. It must also weigh less than 20 pounds. The second area of testing will be its usefulness. Does the device work as intended? Is the device capable of push and pulling the aircraft? Is the device easy to use? Is it easy to take apart and put back together? If these areas of testing are passed, the project will be a success and does not require more redesign.

Method/Approach (How will you test)

In order to test these two areas, how the device will be tested must be decided upon. For the first area, the device will be weighed to determine if it fits in the weight restriction. After this is done, it will be taken apart and stored in the plane to see if it fits the size restriction.

The second area of testing will involve using the device to maneuver the Tandberg’s plane around. Pushing, pulling, turning, etc. This will be both using the tow bar portion with the drive train, and without, as the device is intended to be used separately from the drive train when the time calls for it. You can see below for the general timeline of testing.

The following is the method of testing for the size and weight restrictions:

Weighing of the device.
Storing the device in the plane.

The following is the method of testing that will be used for this device will be a practical use test. For the tow bar portion of the test, the testing will include the following:

Pushing and Pulling of the airplane through the power of the device alone and calculating max velocity. Goal is 0.5 m/s, or approximately 1mph.

The following is the method of testing for the practicality of the device’s use portion of the test.

It can be taken apart and stored in less than 2 minutes.

Testing Expected Results

The expected results are that every test should be successful. Much of the design and analysis is over engineered in certain ways to make sure of this. The goal is for the Tandberg Family to be able to use this device as soon as it is done, and the way that everything has been designed should allow for that to be a reality.

Testing Results

The results of the testing are split. In the first test. overall, the device works as expected. It can push and pull the plane at a comfortable walking speed. However, the speed does not quite match the design requirement/goal. In the two tests the results were;

Pushing: 0.285 m/s

Pulling: 0.415 m/s.

As can be seen, the results are below the goal of 0.5m/s. However, during actual testing, the speeds were found to be quite nice on the user and allowed for an easier time seeing what was behind the plane being pushed. So, while the device was not as fast as the goal set in the beginning of the project, still did 2 things. First, it was able to successfully push and pull a plane with only the power of a drill. And Second, was able to push and pull the plane at a comfortable walking speed. Overall, this test is a success.

In the second test, the size of the device was tested. For this test, the device was taken apart into its storage size, and attempted to be place into the plane’s storage area. With the device taken apart, it was able to easily fit into the plane’s storage area with not size issues.

Going along with the devices size, the weight of the device was of importance as well. For this test, the device was placed on a scale and weighted. The goal for this project was to have the device weight less than 15 pounds. Unfortunately, due to some design choices, many parts brought the weight much higher than expected. Overall, the weight of the device is 31.5 lbs. Much too heavy for normal everyday use. However, this device has gone though many different versions of its design, and just from the testing, many ideas have been brought up to take much of the excess weight away making it much closer to the original goal. In future iterations of this project, these ideas will be explored.

The final test that was performed was the practicality test, where the user was timed taking the device apart, and putting the device together. This is important because when the device is together, it is much to big and be stored in the plane. The user much be able to get all the parts out of the plane should be able to put it together in less than 2 minutes. During the testing, it was found the device’s design was not as practical being taken apart and put together as it seemed when the parts were chosen. In the testing, the time taken to take the device apart was 4 minutes and 41 seconds. Along with that high time, it was found to be much easier taking the device apart than putting it back together. The time it took to put the device together was 9 minutes and 18 seconds.

Overall, these test results show a device that works as designed. It is able to push and pull a plane by its own power, and is able to fit in the plane. It just is much more difficult to put together and take apart than was originally expected, and the device is very heavy overall. In future designs, these 2 areas must be addressed.

Testing Videos

Testing Issues

There were a few issues that came up during the testing of this project. Many of which came from the device. Many areas of the device were found to be weak at the forces being applied by the device. Because brackets were being used to attach every part together, if a bracket was not strong enough to hold the forces, the parts would bend out of place. This was found mostly on the actual tow bar portion. Because of this, more parts needed to be bought to strengthen this portion of the device. Once the parts were bought and assembled, the device worked much better.

Another issue that came up was the gear box grinding. This was taken apart and put back together many times trying to find where the problem was hiding, and whether the gears were meshing correctly. Finally, it was found that a shaft coupling was grinding on one of the bearings, and once that was taken off, the whole device worked much smoother and normally.

The final issue that was found was the connection point of the device to the plane was not fitting correctly. On the nose wheel of the plane, there is a screw that sticks out about an inch behind the attachment point. Because of this, the tow bar attachment point parts needed to be modified to be shorter on one end. Once these parts were modified, they fit perfectly on the attachment point and worked normally.

Devon Tandberg