|This article is outdated. (July 2013)|
|Professor:||Mark D. Maughmer|
AERSP 404H is offered by the Pennsylvania State University as Flight Vehicle Design and Fabrication II, as an upper-level engineering design and capstone course. This course receives funding as a member of the Space Grant Colleges and Pennsylvania Space Grant Consortium. Projects currently revolve around the Kremer prize and manned gliders.
The Department of Aerospace Engineering of The Pennsylvania State University has offered, in its undergraduate curriculum, a rather unique flight vehicle design and fabrication course that attempts to provide aerospace-engineering students with a training that is both comprehensive and applied. The course has a strong "hands-on" component, with students designing and fabricating modern high-performance sailplanes. Students experience the cooperative, multi-disciplinary team environment that is essential for solving problems related to the design of an aerospace vehicle.
The course concept is based on similar student groups at German universities, the Akademischen Fliegergruppen (Academic Flying Groups) or, abbreviated, the Akafliegs. The members of these groups concern themselves with the design, construction, testing, and flying of modern sailplanes. Although not part of the official curriculum at their respective school, the groups receive some logistical support from their institutions. In brief, organizational structure is similar to that of an American Greek-letter social fraternity, except that the focus of interest revolves around soaring. At eleven German colleges, these groups, some which have been in existence since the early 1920s, are strongly involved in sailplane related research, often with the support by the German Aerospace Research Center, DLR, which viewes these organizationthis as an effective and uncomplicated way of training future engineers.
In 1990, a report from the Engineering Coalition of Schools for Excellence in Engineering Leadership (ECSEL) found that American schools didn't promote group work, creativity or hands-on training. Maughmer and another Penn State faculty member created the course to combat these shortcomings. The course doesn't rely on traditional tests or even a set course syllabus. Instead, specific lectures are given to address whatever problems the students would be having in the construction of their gliders. Since then in inception of AERSP 404H, they students has started many projects and reached many milestones. Early on, work was focused on the design and testing of small radio-controlled gliders and the first full-scale student sailplane design.
Students work in 4-6 person groups that work on various projects. Projects include wing construction, propeller driven tricycle, wing loading test, rocket launched gliders, paper airplanes, and model aircraft. To a large part, the learning experience can be related to the integrated nature of the design course, as well as to the interaction of undergraduate students at all levels of the program. There are three components to the course, lecture, design, and fabrication, meeting the official course objectives:
- Complete the preliminary design for an aircraft such that it satisfies assigned specifications
- Design a system, component, or process that meets given requirements in aircraft systems
- Identify, formulate, and solve engineering problems
- Function on multi-disciplinary teams
- Communicate and present effectively the results and consequences of their technical efforts
- Determine what the ethical responsibilities are to themselves, to employers, and to society
The main purpose of the lecture component is to provide the students with the theoretical background required for their design and fabrication activities. Hence, it is kept quite flexible in order to be able to address current needs and problems. The lecture emphasizes the basic theory of sailplanes and their design requirements. The challenge for the professor is to present lectures that provide a positive learning experience for the fourth-year, aerospace engineering student, who might have been in this course for the past four years, as well as to the freshmen, who might have no background at all in aerospace engineering.
After an introduction to basic sailplane related subjects, other topics are emphasized that are relevant to aircraft design, such as aerodynamics, stability and control, structural design, design and fabrication of composite structures, performance analysis of modern sailplanes, general design methods, and some sailplane history. For example, a brief description of existing sailplane designs makes the students appreciate the solution found by earlier designers facing similar problems.
Students learn in class about the basic design criteria of sailplanes. This knowledge is then applied by the students in their the design groups.
Beyond these technical tasks, the lecture also covers other, less obvious, but important engineering skills. These instructions include basic and general aircraft-design principles, technical report writing, presentation methods, as well as professionalism and ethics. Besides the formal lecturing, the students' skills and abilities in these subjects are constantly challenged through their design and fabrication activities.
Lectures topics include:
- Human Power Aircraft Power
- Bomber Design
- Electrical Power Design
- Aircraft Design Optimization
- Aerodynamics of Human-Powered Flight
- Engineering Design Process
The second component is concerned with design groups of four to six students, in which the students design and analyze sailplanes, such as their performance, structure, stability and control, etc. Students are encouraged to constantly think about design and learn "to feel" the right answer before calculations and to create a small community with all skill levels similar to the Akaflieg. Small design projects reinforce this methodology, with projects such as paper airplanes. Furthermore many design projects take more than one semester to complete, and can typically the span two to three years in length.
The third component is the fabrication of parts that have been designed and analyzed theoretically. An engineering lab is currently assigned for fabrication, however students utilize various other locations such as the Penn State Learning Factory. Common fabrication tools include hot-wire foam cutter, belt sander, vacuum engineering tools and drill press.
The PSU Griffin
In the early 1990s, the class was tasked with designing and fabricating a high-performance sailplane. The Griffin is the name given to the first sailplane this class designed. This name was selected over the less politically correct moniker "The Iterator" which reflected group frustration over a lack of progress toward fabrication of a full scale vehicle. After the design was finished, a plug was made out of wood, foam, and fiberglass. From this, molds for the glider were then made. During the spring of 2001, the molds were used to produce a test cockpit section. This achievement marked the first time an actual glider component was produced from the class's original design.
Work on the Griffin curtailed over the recent years as more time was spent on assembling the Falcon and designing and Easy-to-Build sailplane. The plug for the Griffin now hangs above the low-speed wind tunnel in the basement of Hammond.
The American Falcon was one of three sailplanes on which the class has been working on in the early 2000s. This glider was donated to the course after the wing of another sailplane of this design had prematurely failed during a structural-load test. The manufacturers of the plane found that the wings could not withstand the maximum loading plus the safety factors required by the FAA. The problem occurred at the wing's root rib, which is located at the wing/fuselage junction of the aircraft. The failure of the root rib has been a problem studied by several former design groups. Recommendations have been made by these groups and were implemented in lab. The Falcon is a $24,000 kit plane; meaning the glider's major components arrived prefabricated. However, most of the control system and landing gear needs to be built. It is up to the class to actually assemble the glider. Most of this work is done during evening lab hours by different lab teams who specialize on a certain component.
Easy Build Sailplane
At the start of the Fall 2001 semester, students began working on the design of an Easy-to-Build glider in design groups. The goal was to design a glider that can be completely fabricated by the class within two years. During Fall 2001 semester, four teams prepared and presented individual conceptual designs. From these four designs, the best two were chosen and work progressed on each during the Spring of 2002. With the two preliminary designs in hand, four different groups worked to consolidate the best features of each glider the of Fall 2002. Key design considerations included:
- Structural design requirements set by JAR22
- Standard sailplane launching methods (tow-plane and winch-towing)
- Minimum airspeed of 20-25 knots
- Maximum airspeed of 60 knots
- Total cost must not exceed class budget
- Constructed using readily available materials
- Aircraft must be modular
Detailed designs were worked in four different teams. Each team was assigned to a component of the glider. These components are the fuselage, wings, empennage, and control system. Design analysis limited amount of preliminary work is currently being done in lab as a forerunner to fabrication of the glider. It was designed to be constructed without using advanced fabrication methods. The final weight was 250 pounds and estimated cost of $(2001) 1850.
Spirit Wing Loading
A Spirit Sailplane has been provided to conduct a wing loading test on an American Spirit XL glider. The spirit glider has a design flaw where the wing load is not carried symmetrically and failed at the static wing loading test with the root rib buckling at 5.9g. The failure is due to the load no adequately being transferred to boron root rib; summation of loads from lift force, bending movement, and torsional movement contributed to failure. The glider's owner performed a do-it-yourself repair on the wings and has commissioned the team to test the repair. A steel jig will be constructed to mount the wings. The shear flow was calculated in 14 idealized sections. Moments were taken about a point to find the location of the shear center. 15 lb sand bags will then be distributed, based on shear flow calculations, along the underside of the wings to create a force equivalent to 6g. The shear center was calculated so that the wing will be loaded in pure bending with no induced torque.
AIAA Design Build Fly
Penn State competes in the AIAA Design/Build/Fly competition. The Nittany Griffin and its design team traveled to Arizona in Spring 2007 for the competition. They finished 2nd in the Speed Event and 3rd in the Endurance Event. There were 50 Entrants in the Competition; 39 Showed up and 19 actually flew. The team finished 12th overall and MIT was awarded 1st prize.
|Standing||Entry Name||Paper Score||RAC (System Wt)||Flight Score||Total Score|
|Standing||Entry Name||Paper Score||RAC (System Wt)||Delivery Flight||Payload Flight #1||Payload Flight #2||Total Flight Score||Total Score|
|22||Spirit of Happy Valley||75.5||6.18||15.96||0.00||0.00||15.96||1205.2|
Human-Powered Aircraft: Zephyrus
The progress of the human-powered aircraft design has phased more and more toward the numerical analysis of the original parent aircraft based design. Previous human powered aircraft including the MIT Daedalus, the Gossamer Albatross, Musculairs I & II, and the Velair were researched during the design phase. Initial aerodynamic and structural concerns have been taken into account leading toward the further refinement of the wing, empennage, and fuselage design. In addition, propeller construction methods are being studied in depth preparing for a finalized design and the beginning of the construction phase. A simulation program is being developed, and integrative techniques are being studied in an effort to effectively train the future pilot. An iterative process is being used to appropriately size the wing and tail taking into effect, in turn, aerodynamic and structural features. Important sizes at the present include a wing span of 17.5 m, wing area of 10.94 m2, root chord length of 0.75 m, taper ratio of 0.029, aspect ratio of 28 and empty weight of 26.5 kg. Flying characteristics include a lift coefficient of 0.8 at cruise (1.3 at stall), and a Reynolds number range from 350,000 to 725,000.