Comparison of the Standard Thermal Mix Model to an Alternate Approach of Sailplane Winglet Design and Their Resulting Impact on Cross-Country Flight Performance
Open Access
Author:
Cooper, Jenna
Area of Honors:
Aerospace Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Mark David Maughmer, Thesis Supervisor Namiko Yamamoto, Thesis Honors Advisor
High-performance racing sailplanes are able to exploit sources of lift in the atmosphere and have regularly flown distances of over 1,000 kilometers. Without an engine, sailplanes are always sinking relative to the airmass they are flying in, forcing them to rely on various weather phenomena to stay aloft. Typically, cross-country soaring involves several cycles of climbing in lift, usually by circling in thermals, then utilizing altitude gained in a straight glide to the next thermal. A sailplane must fly efficiently both while climbing at low speeds and high CL’s and while gliding at higher speeds and low CL’s in order to obtain the fastest average cross-country speed. The speed-to-fly while gliding is determined by the strength of the thermals present on a given day. Therefore, the weather model used during the design process will determine the sailplane’s predicted performance and directly impacts the resulting design. An alternate weather model that considers a wide variety of thermal strengths and cross-country performance at different wing loadings was investigated in this study. This method produced a different wing area result than the thermal mix model originally used in designing the Ventus 3. The alternate method used in this thesis shows that additional cross-country performance gains may be available by increasing the wing area by 5 to 10 percent on the Ventus 3. It is unknown which method will result in better cross-country performance overall. Future work can look to quantify this performance gain and any differences in soaring strategy that may improve average cross-country speeds.
