Every year, the Society of Automotive Engineers (SAE) sponsors the Aero Design competition. This competition presents to students the challenge of designing an airplane that can maximize the amount of payload while, at the same time, minimize the weight of the aircraft. The team has chosen to participate in the SAE Aero West competition in Van Nuys, California. The competition is to be held from March 6-8, 2009. The team will design and build a remote control (RC) airplane that meets the specifications and regulations as stated by the SAE Regular Class competition. The client for this project is a faculty member from Northern Arizona University, Dr. John Tester.
During the first semester of the project, the team aims to complete the basic design of the airplane. This includes the selection of wings, landing gear, fuselage, tail design, etc. Detailed drawings of all parts will aid in the construction of the airplane; more specifically the fuselage, wings, and tail. These drawings are also required by SAE. Once a basic prototype has been constructed, the team hopes to spend the remaining time refining the design to maximize the thrust produced from various combinations of propeller blades with the supplied engine. Most importantly, the team aims to qualify the aircraft for flight during the competition in March.
The second semester of the project is aimed at finishing the design of the aircraft and making design changes as test flights are conducted. The documentation and presentation of the airplane are also major tasks to be completed during the second semester.
January 15, 2009
The winter break for most college students is a time of relaxation and rest. However, team Ninja Turtles has been hard at work completed the basic construction of the wing of the airplane. It has taken a long time to complete this main component of the wing, but the team believes that the wing is the most important aspect of the airplane, and therefore should be of the highest quality possible. The wing has since been created and is in two halves. This allows for easier storage during construction of the rest of the airplane.
January 31, 2009
The Tail of the airplane has been completed and made as light as possible so as to avoid an aft center of gravity. The tail is ready to be joined to the body of the airplane which has begun construction of the last week.
February 18, 2009
The body of the airplane has been completed and the tail has since been joined to the fuselage. The engine mount has arrived and the landing gear has been manufactured. The team hopes to finish the manufacturing of the aluminum backbone that will carry all of the forces we expect to experience during flight.
February 20, 2009
The airplane is now ready for monokote. The process of putting a skin onto the airplane should not take too long. During this process, all of the internal electronic components are to be tested and verified to work. Once the monokote is completed on the wing, we will be able to join the two halves of the wing together with the internal support members and the kevlar wrap. We expect this joint to be the strongest member of the airplane, as it is perhaps the most critical member of the airplane that is mostly made out of wood.
February 25, 2009
The second semester of the project is upon us and we find ourselves with a completed prototype. The objective is to now fly the airplane and determine what modifications must be later made in order to obtain optimum flight.
The wing was the first main piece to be complete. The tail quickly followed. The last major part to be built was the fuselage of the airplane. Once completed, however, the components were assembled along with landing gear, servos, internal electronics and an engine.
We hope to test the airplane during the last weekend of February. This will hopefully give us ample time to make any final changes necessary to the airplane so that we are ready for the competition during the following week. The test flight will take place in Lake Havasu, AZ. This location is similar to the flying conditions of Van Nuys, CA. The elevation of Lake Havasu is about 1000 ft, while Van Nuys is listed as being close to 800 ft.
March 2, 2009
The test flight went better than expected. The landing, however, was rather rough. The team learned a lot from the maiden voyage of the airplane. We learned that our center of gravity was far too back compared to the quarter chord of the wing. Modifications to the aircraft were made, and the aircraft was entirely rebuilt in less than 48 hours. Thanks to the dedication of the team members and their significant others, the new airplane, dubbed "splinter" is ready for flight at the SAE competition this weekend of March 6-8, 2009.
As a result of this initial test flight, a few changes were made to the initial design. These changes are as follows:
The size of the rudder was increased to 4 inches from the initial 2.5
inches.
The location of the Center of Gravity was moved forward.
The fuel tank was moved forward and position vertically.
The receiver and all electronics were moved forward.
The backbone was extended and moved forward.
The cargo hold was modified to move the location of the lead
weights forward.
The landing gear was shifted forward and angled more forward.
Downthrust was added to the headwall/engine mount to
account for backwash of the propeller.
March 10, 2009 - competition results
The competition went well for us. Though we were penalized points due to some structural changes made to the wing during redesign, the airplane was a success. The oral and written presentations went well, placing the team initially in 23rd place out of the field of 32 teams. Though it may not have been in the top percentile of the field, we feel that this was well done considering that no one on the team had previously competed in a similar competition of this nature. The airplane would have to prove its worth on the runway and in the air.
The team decided to fly the airplane at three different weights. The first flight conducted was at empty weight of about 11 pounds. The plane took off in a very short distance, and flew well. Joe hadn't flown the plane before, so time was spent in the air learning how to navigate with the control surfaces. It was a long flight. The landing was successful and the team went back to the table to add some monokote to the junction of the wing to the ailerons. This additional monokote, in theory, would increase the control of the pilot over the plane. In addition to this minor addition, the ailerons were trimmed a little bit more so as to compensate for the minor wing warp that was created during the construction of the wing.
The second flight was with the design weight of the airplane carrying 12 pounds. This made the overall weight of the airplane at about 23 pounds. The airplane took off on the first attempt just as it was crossing the 200 foot line on the runway. The flight was flawless. The landing was successful, however it did tip over on its nose as it touched down on the runway. This was due to a combination of the small amount of wind and the landing gear being close to the center of gravity of the plane. The bonus added to our score for flying with a successful design weight was 19.88 out of 20 possible points. The current place of team Ninja Turtles was 5th. The team decided to sit out the next round of flying and grab lunch.
Upon return from lunch, team Ninja Turtles had slipped to 9th place as other teams were now carrying more weight. The decision of the team was to load up the airplane with all the weight we had, an amazing 19.8 pounds of lead. Because the plane had barely taken off within the allotted 200 feet during the last flight, it was decided that we need to change out the wheels. The current wheels were soft and spongy, which allowed the plane to land in very short distances. After consideration was given to a harder rubber wheel, the wheels were swapped out and the plane was ready to fly. On this third attempt of flying, the center of gravity of the plane was located too far forward, and there plane was unable to take off. The team then moved some of the weight in the cargo bay a couple inches aft in the cargo bay. This changed the center of gravity of the plane just enough so that on the next attempt, the airplane took off right at the 200 foot line and made a successfully flight. However, upon landing the airplane still had issues with the nose tipping forward. The airplane experienced an extremely rough nose slide upon contact with the tarmac. The flight was deemed a success as nothing from the plane fell off during flight or landing.
The overall placement of team Ninja Turtles in the 2009 SAE Aero Design West competition was 9th place.
