PFR - Aerospace Engineering Sciences Senior Design Projects ...

More documents

Recommendations

Info

Project Final Report – CUDBF April 30 th , 2009 ASEN 4028: Aerospace Senior Projects 4.0 System Design-To Specifications Author: Jarryd Allison Co-Author: Ben Kemper 4.1 Aerodynamics Design-To Specifications The aerodynamics subsystem was delegated the responsibility of the initial configuration of the aircraft. The Buff-2 Bomber was designed to be a fixed wing aircraft that could also be folded in order to fit within the 2ft x 2ft x 4ft storage containers. A flying wing was selected due to its small number of surface extremities (limited to 2 wings) that can be folded and deployed quickly. The aerodynamics team also selected the configuration that would meet the maximum 100 ft takeoff requirement while still being able to carry all wing stores along with the external bottle/tank full of water. The subsystem also worked on reducing the overall weight of the plane, which favors the lightweight design of the flying wing. These requirements dictated the main tasks of the aerodynamics subsystem throughout the design process. 4.2 Missions Design-To Specifications The Missions subsystem was then tasked with meeting the system requirements relative to holding the wing mounted and centerline stores along with storing the aircraft in the container. The aircraft must be able to fly three missions completely, seen below in Table 4. Table 4: Missions to be Completed by the Aircraft Mission Mission Specifications Scoring 1 Empty 4L tank, 2 laps Equation 3 2 Full 4L tank, 4 laps Equation 4 3 Timed rocket loading, four laps, drop store at completion of each lap Equation 5 The importance of the aircraft being quickly deployable with mounted stores that can easily attach to the aircraft must be stressed, as assembly time plays a role in each mission score calculation. In order to be successful, the aircraft must complete each mission with no stores being released while airborne. This presents quite a design problem for the Missions subsystems. Each store must release on command, yet must not fall off during flight. Free-play must also be minimized so as to not affect the aircraft performance. 30
Project Final Report – CUDBF April 30 th , 2009 ASEN 4028: Aerospace Senior Projects 5.0 Development and Assessment of Subsystem Design Alternatives Author: Ross DeFranco Co-Author: Mark Findley 5.1 Aerodynamics Subsystem Design Alternatives 5.1.1 Aircraft Geometry The only known variable in terms of aircraft geometry was the wingspan, which was determined by payload placement requirements to be no less than 5ft. The aircraft geometry affects the stability of the aircraft, and therefore, the best sweep and taper were chosen. Additionally, the geometry of the aircraft was also driven by the requirement to fit in a 2ft x 2ft x 4ft box. Athena Vortex Lattice (AVL) [5] was used in conjunction with MATLAB [6] and the program AutoIT [7] to generate different geometry configurations, outlined further in Section 10.1. The static margin for every combination of leading edge sweep angle (between 0 and 25 degrees) and taper ratio (between 0 and 1.0) was analyzed in increments of 5 degrees and 0.1, respectively. MATLAB was used to generate geometry files compatible with AVL for every combination. This analysis helped narrow the selection of the optimal sweep angle and taper ratio. The code used to perform this analysis can be observed in Appendices B and C. This analysis was not performed separately for the quarter chord sweep angle and trailing edge sweep angle since they are dependent on the leading edge sweep angle. Figure 12 shows the variation in leading edge sweep angle and taper ratio as a function of static margin. Figure 12 indicates that sweep angles between 0 and 15 degrees produce a negative static margin for every possible taper ratio. A negative static margin indicates that the C.G. of the aircraft is aft of the aerodynamic center. As static margin increases, the responsiveness of the aircraft to pilot input decreases, but, longitudinal static stability increases. So, a negative static margin refers to poor longitudinal static stability, which is undesirable for a flying wing configuration since flying wings are inherently unstable. 31
Page 1: University of Colorado Design/Build
Page 4 and 5: Project Final Report - CUDBF April
Page 82 and 83:
Project Final Report - CUDBF April
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166:
show all

PFR - Aerospace Engineering Sciences Senior Design Projects ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?