Designing a Green Aircraft; Cal Poly's 2009 Undergraduate Aircraft Designs

Abstract

(RFP) asked for an advanced, environmentally compatible commercial transport design that seats 150 (dual class) passengers with US transcontinental range capability. The design was to show significant improvements in fuel burn (with associated CO2 reduction) and reduced community noise, while maintaining or improving productivity and passenger comfort standards. The Senior Aircraft Design course at Cal Poly, San Luis Obispo has evolved over the years into a highly regarded design program [2-9] . In the 2008-2009 academic year, the students in the course responded to the design competition with six team submittals. The evolution of the six team designs will be presented from 37 individual student design concepts at the end of fall quarter, creation of team baseline designs at the beginni ng of winter quarter, four subsequent design iterations and industry critical reviews throughout winter and spring quarters, to submittal of written reports to AIAA in early June 2009. The cornerstone of the Cal Poly design recipe is close cooperation with industry. The primary components of the cooperation are the trips each Senior Design class makes each year. Each trip has two primary phases. First, an up close tour of a working industry facility. Second, the student participation in a critical revi ew session performed by a panel of technical experts supplied by the company. During 2008-2009, the trips included Boeing Phantom Works in Huntington Beach and Long Beach, Lockheed Martin Skunk Works in Palmdale, Northrop Grumman Integrated Systems in El Segundo, Air Force Test Flight Center at Edwards Air Force Base, and a return visit to Boeing Phantom Works in Huntington Beach with Boeing Commercial Aircraft in Seattle tied in by remote telecommunication. Each and every critical review session with industry, along with internal pre-reviews with Cal Poly professors and lecturers, resulted in major shifts in team design philosophies and priorities. During the development of individual student design concepts, thinking “outside of the box” was highly enco uraged. Representative concepts will be presented with their advanced technology features (Figures 1 & 2). The major design theme of the six designs chosen for presentation at Boeing Phantom Works was passenger comfort. Most of the designs featured double aisles and larger passenger seats and aisles. Performance improvements over the Boeing 737 and Airbus A320 were small, driven only by improved higher bypass ratio engines. Subsequent discussions regarding the need for improved aerodynamic performance led to most teams adopting high aspect ratio wings, located above the fuselage with strut bracing to reduce wing weight. The historical regression-based weight methodology did not predict matching of (L/D)max and (L/D)cruise. Refined weight models were t hen created and validated, by comparison with existing transport aircraft, to realistically account for increase of wing weight with increased aspect ratio. Aspect ratio trade studies were then re-evaluated and resulting aspect ratios reduced from 12-27 to 11-12. Most high wing designs with accompanying strut bracing were abandoned with reduction in aspect ratio. In the end, three teams chose unducted fan engines and three teams chose advanced high bypass ratio turbofans. All unducted fan engines were located on the aft fuselage similar to the MD-80 family of aircraft. Turbofan engines initially were located under the high wing or on the aft fuselage. Engine location trade studies resulted in all three turbofan driven designs adopting over-the-wing locations.