Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations
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2010
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High lift-to-drag ratios of the contemporary sailplanes make them the most energy efficient flying vehicles. On the other hand, this capability may become their serious disadvantage during the landing, if their aerodynamic deceleration devices become inoperable in flight. Not being able to dissipate the excess energy quickly when close to the ground, they may fly over the available landing ground and finish up in front of the obstacles, with still too much energy to land and not enough to fly over them. Beside the sideslipping flight in final, where energy is dissipated through the increased sideforce drag, another solution to this problem has been offered in a number of papers. By numerical analyses they have shown that landing distance in such cases could be minimized using rather complex oscillating flight paths in vertical plane. Although relevant distance reductions could be achieved through them, performing such paths in practice would require exceptional piloting skills. Instead... of that, in this paper much simpler approach profiles have been analyzed, based on two types of cosine speed variations with constant periods and amplitudes, which could be flown by pilots of average flying experience. After establishing a quick convergence algorithm, numerical solutions for several typical cases, belonging to two general speed variation types, have been presented. The same initial and terminal reference energy states have been used. Although the distance reductions are smaller than obtained by distance-minimizing techniques, operational simplicity of presented techniques and some specific advantages prove them valuable within this categoiy of problems.
Кључне речи:
sailplane / inoperable spoilers / final approach / cosine speed variationsИзвор:
Strojniski Vestnik/Journal of Mechanical Engineering, 2010, 56, 7-8, 436-446Колекције
Институција/група
Mašinski fakultetTY - JOUR AU - Stefanović, Zoran AU - Kostić, Ivan PY - 2010 UR - https://machinery.mas.bg.ac.rs/handle/123456789/991 AB - High lift-to-drag ratios of the contemporary sailplanes make them the most energy efficient flying vehicles. On the other hand, this capability may become their serious disadvantage during the landing, if their aerodynamic deceleration devices become inoperable in flight. Not being able to dissipate the excess energy quickly when close to the ground, they may fly over the available landing ground and finish up in front of the obstacles, with still too much energy to land and not enough to fly over them. Beside the sideslipping flight in final, where energy is dissipated through the increased sideforce drag, another solution to this problem has been offered in a number of papers. By numerical analyses they have shown that landing distance in such cases could be minimized using rather complex oscillating flight paths in vertical plane. Although relevant distance reductions could be achieved through them, performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on two types of cosine speed variations with constant periods and amplitudes, which could be flown by pilots of average flying experience. After establishing a quick convergence algorithm, numerical solutions for several typical cases, belonging to two general speed variation types, have been presented. The same initial and terminal reference energy states have been used. Although the distance reductions are smaller than obtained by distance-minimizing techniques, operational simplicity of presented techniques and some specific advantages prove them valuable within this categoiy of problems. T2 - Strojniski Vestnik/Journal of Mechanical Engineering T1 - Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations EP - 446 IS - 7-8 SP - 436 VL - 56 UR - https://hdl.handle.net/21.15107/rcub_machinery_991 ER -
@article{ author = "Stefanović, Zoran and Kostić, Ivan", year = "2010", abstract = "High lift-to-drag ratios of the contemporary sailplanes make them the most energy efficient flying vehicles. On the other hand, this capability may become their serious disadvantage during the landing, if their aerodynamic deceleration devices become inoperable in flight. Not being able to dissipate the excess energy quickly when close to the ground, they may fly over the available landing ground and finish up in front of the obstacles, with still too much energy to land and not enough to fly over them. Beside the sideslipping flight in final, where energy is dissipated through the increased sideforce drag, another solution to this problem has been offered in a number of papers. By numerical analyses they have shown that landing distance in such cases could be minimized using rather complex oscillating flight paths in vertical plane. Although relevant distance reductions could be achieved through them, performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on two types of cosine speed variations with constant periods and amplitudes, which could be flown by pilots of average flying experience. After establishing a quick convergence algorithm, numerical solutions for several typical cases, belonging to two general speed variation types, have been presented. The same initial and terminal reference energy states have been used. Although the distance reductions are smaller than obtained by distance-minimizing techniques, operational simplicity of presented techniques and some specific advantages prove them valuable within this categoiy of problems.", journal = "Strojniski Vestnik/Journal of Mechanical Engineering", title = "Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations", pages = "446-436", number = "7-8", volume = "56", url = "https://hdl.handle.net/21.15107/rcub_machinery_991" }
Stefanović, Z.,& Kostić, I.. (2010). Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations. in Strojniski Vestnik/Journal of Mechanical Engineering, 56(7-8), 436-446. https://hdl.handle.net/21.15107/rcub_machinery_991
Stefanović Z, Kostić I. Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations. in Strojniski Vestnik/Journal of Mechanical Engineering. 2010;56(7-8):436-446. https://hdl.handle.net/21.15107/rcub_machinery_991 .
Stefanović, Zoran, Kostić, Ivan, "Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations" in Strojniski Vestnik/Journal of Mechanical Engineering, 56, no. 7-8 (2010):436-446, https://hdl.handle.net/21.15107/rcub_machinery_991 .