Introduction to the MR Drone
The M-R (Multipurpose-Rotor) Drone is a partially autonomous unmanned aerial vehicle which is capable of vertical take-off and landing (VTOL) as well as fixed wing flight like a traditional plane. These characteristics give it the unique ability to fly long distance but also take off and land anywhere. This eliminates the need for the plane to be hand launched or the need for a runway. Additionally, the ability to fly as a fixed wing plane allows the MR Drone to fly for a longer duration than a rotary vehicle. Because of this versatility, the MR Drone is suited to many situations that traditional UAVs are not.
The Design Story
The Beginning –Team MR Drone wanted to create something that was exciting, unique and most importantly useful! After our sponsor Dr. Leang suggested something in the aerial robotics field, brainstorming lead to ideas for search and rescue, law enforcement, and defense applications but most of these had already been done or were unrealistic due to current limitations of the aerial vehicles already available. So, it was decided to actually tackle these limitations. In general, there are two types of vehicles: rotary and fixed wing. Rotary vehicles are great because they can maneuver well in confined spaces and can take off and land vertically (VTOL) without being launched or requiring a runway. Unfortunately, the flight time on these is extremely limited and most quadcopters have flight times less than 30 minutes. Enter fixed wing aircrafts! These can potentially be in the air for hours at a time! But wait, what about being maneuverable and taking off vertically? Well, our team decided that this just wouldn’t do and that we ought to design a vehicle which could combine the advantages of each type of vehicle. At this point, images of the V22 Osprey such as the one shown to the right may be popping into your head and you might be asking, “Hasn’t this already been done?” On a very large scale, the V22 has indeed accomplished this objective, but when looking at the scale our team was interested in, the solutions are few and far between.
In order to achieve this goal, a few things were apparent. We needed to learn a whole lot about the ins and outs of both planes and quadcopters, and we needed to do some serious brainstorming about clever ways to combine these two very different platforms.
The Design – With our design goal in mind, Team MR Drone set out to begin brainstorming, proposing, modifying, scrapping, brainstorming, proposing….well you get the idea. Several team meetings and a few heated discussions later, the team decided on a concept; the rotors used to create lift for VTOL would be rotated to be used in forward flight much like the Osprey. Once the concept was decided upon, specifics began to take shape. We would use a base plate to which our wings would attach, as well as a servo which would rotate a secondary frame. A simple 3D rendering of this concept is shown next to the actual prototype which was built to test the rotating frame as well as VTOL capability.
As with most designs, the first round was not completely successful. Stable VTOL was achieved, which demonstrated that our configuration was generating more than enough lift to take off hover and land – all without crashing! Unfortunately, the servo used to rotate the upper frame was unable to return from the forward flight position to hover position. This was a combination of the frame and components being heavy and the servo being underpowered. More importantly than this failure though, the prototype was hideous; wires were everywhere, components were zip tied to the frame, and we were not at all satisfied.
So, back at the drawing board, the team came up with a second design shown below which really excited everyone. This design had it all: it could house all of the components, hide wires, protect electronics from Mother Nature, and also created a unique way in which to transition from hover to forward flight mode. Yes, we had created the perfect design – at least we though so until we found out it would cost $5000 to fabricate. After months of iterations, plenty of late nights, and a good cry or two the design went down the drain and we again started from scratch.
Finally, it was decided that the next idea would be designed specifically with manufacturing capabilities in mind – imagine that. With time, resources, and money running out the team developed a new frame which was a compromise between the sleek, organized awesomeness of the second design with the ease of manufacturing of the second design. Pictured below is the result (without tail and rudder). This design utilized a unique type of servo motor which has an output on both sides rather than one. By attaching the carbon fiber tubes which house the motors and rotors to each side of the servo, we can rotate them to provide thrust at any angle we need.
Testing & Results
Testing – Several key tests were performed to determine whether or not the design met the set criteria. The most importante of these tests include hover testing and forward flight testing.
Hover Testing – To test the hover capabilities of the M-R drone, all four rotors were fixed in the vertical position.
After that, the M-R drone was positioned in an open space and was controlled via remote control for the first test.
Stability was a main concern about hovering. The team knew that the wings and fuselage would provide extra drag in VTOL. However, the hover mode was stable enough to perform several tests successfully. The flight controller was able to compensate for the unconventional weight distribution.
Forward Flight Testing – To test the forward flight of the M-R drone, the rotors were fixed in the forward position.
To launch the M-R drone, a launching rack was fabricated out of PVC pipe and placed on top of a car. The rack was angled so that the wings could catch lift to initiate flight. The major flaw with this method of testing is that we could only perform the test once. If the M-R drone were to crash, we couldn’t perform another test. Which is unfortunately what happened.
After viewing the video, we noticed that the M-R drone did manage to achieve lift very briefly. However, one of the rotors caught on the side of the launching rack and caused it to crash over the side of the car.
The Results – While not as pretty as the streamlined design would have been, this design is a major improvement of the original proof of concept. While not every test was successful, the design still proved to be effective. Given more time and resources, the M-R drone would meet all the criteria and exceed them. Much was learned from these tests. The flight controller was more than capable of maintaining hover. Lift is definitely possible with our design. However, a better testing method would be necessary to perform multiple tests. From previous calculations made, the M-R drone must achieve a forward speed of 25 miles an hour. When lift was observed, the forward speed of the M-R drone was determined to be 28 miles an hour from the car’s speedometer. We couldn’t test the energy efficiency of forward flight due to the lack of sufficient flight time. But from previous experiments and calculations, achieving the goal of 2.5 times hover time is definitely reachable.
About The Team
Alex Woods is a senior in mechanical engineering and is close to a minor in physics. Having taken courses in Aerodynamics and Mechatronics, his experience will help the team effectively create a viable product. Additionally, his experience working with quadcopter platforms in the past has allowed the team to bypass much of the steep learning curve they would have faced otherwise. Finally, he has been the team leader of several successful teams and is the president of the ASME student section. His leadership experience will help the team run effectively.
Conor Laughlin is a senior mechanical engineering student with minors in renewable energy and mathematics. Other than the basic curriculum, Conor has taken courses in composite materials research, advanced mechanics of materials, and internal combustion engines. Conor is also a member of Sigma Phi Epsilon fraternity and has held several leadership positions in his tenure. These leadership skills will help the group maintain focus and accomplish tasks effectively.
Kent Bergantz is a senior in mechanical engineering with a minor in business administration. His broad range of education has allowed him to help the team analyze the project from a different perspective. His business background has aided the team in its general business plan and budget. He has worked on a large number of group projects, which will help the team overcome any internal obstacles that it may face.
Omar Salas is a senior at the University of Nevada Reno and is perusing a Bachelor’s degree in Mechanical Engineering in conjunction with a minor in Renewable Energy. His formal education up until this point has covered all of the basic topics regarding aerodynamics, fluid mechanics, and control systems.