Mass Estimation of Folding Wings

Purpose – Review of mass increase of folding wings applied to passenger aircraft. --- Methodology – Data is obtained from literature (Yarygina and Popov). Data is reworked to build new, simple equations. --- Findings – Wing folds on passenger aircraft are intended to reduce wingspan at the gate. This keeps new, more efficient large-span aircraft in the original wingspan category according to the ICAO Aerodrome Reference Code. A wing fold cuts off part of the wing. The structural loads in the cut are larger if the cut is further inboard. A wing fold at the tip (is basically no fold and) adds no mass. The additional mass of a wing fold increases in good approximation linearly from tip to root. A wing fold at half-span position increases wing mass by about 33%. A one-sided fold is possible. A one-sided fold e.g. 20% from the tip has the same wing mass increase as a fold on both sides 10% from the tip (resulting in the same remaining span after folding). Stowage of an unsymmetrical aircraft with a one-sided fold is more complicated but one such fold may be mechanically simpler than two. --- Research Limitations – Calculating a fold more inboard than 32% of half span is extrapolating given data. --- Practical Implications – Approximating wing mass increase due to a fold can be estimated easily. The equations can be used in a spreadsheet for aircraft design optimization.研究目的：针对应用于民用客机的折叠机翼质量增益开展综述研究。 研究方法：数据取自文献（Yarygina与Popov），并对其进行重新处理以构建全新的简易方程。 研究发现：民用客机的折叠机翼设计初衷为在机场登机口处缩短翼展，使新型高效大翼展飞机能够纳入国际民航组织（ICAO）机场基准代码所定义的原有翼展范畴。折叠机翼通过切除部分机翼实现，切除位置越靠近翼根，切口处的结构载荷越大。若在翼尖位置设置折叠结构，本质上等同于未折叠，不会带来额外质量增益。折叠机翼带来的附加质量近似从翼尖到翼根呈线性增长。在半翼展位置设置折叠结构，可使机翼质量增加约33%。单侧折叠设计具备可行性：例如，单侧在距翼尖20%翼展处折叠，其带来的机翼质量增量与双侧分别在距翼尖10%翼展处折叠的效果一致（折叠后剩余翼展相同）。采用单侧折叠的非对称飞机的停放收纳更为复杂，但此类单侧折叠结构在机械实现上可能比双侧折叠更为简单。 研究局限性：当折叠位置超过半翼展的32%时，相关计算基于现有数据的外推，需谨慎使用。 实际应用价值：折叠机翼带来的质量增益可通过近似方法便捷估算，所构建的简易方程可嵌入电子表格，用于飞机设计优化工作。