Purpose

As measuring flight performance by experimental methods requires a lot of effort and cost, theoretical models can bring new perspectives to aircraft design. This paper aims to propose a model on the direct calculation of wetted area and L/D_max.

Design/methodology/approach

Model is based on idea that the wetted area is proportional to aircraft gross weight to the power of 2/3 (W_g^2/3). Aerodynamic underpinning of this method is based on the square–cube law and the claim that parasitic drag is related to the S_wet/S_wing. The equation proposed by Raymer was used to find the L/D_max estimate based on the calculated wetted area. The accuracy of the theoretical approach was measured by comparing the L/D_max values found in the reference literature and the L/D_max values predicted by the theoretical approach.

Findings

Proposed theoretical L/D_max estimate matches with the actual L/D_max data in different types of aircraft. Among the conventional tube-wing design, only the sailplanes have a very low S_wet/S_wing. The S_wet/S_wing of flying wings, blended wing bodies (BWBs) and large delta wings are lower than conventional tube-wing design. Lower relative wetted area (S_wet/S_wing) is the key design criterion in high L/D_max targeted designs.

Originality/value

The proposed model could be used in wing sizing according to the targeted L/D_max value in aircraft design. The approach can be used to estimate the effect of varying gross weight on L/D_max. In addition, the model contributes to the L/D_max estimation of unusual designs, such as variable-sweep wing, large delta wings, flying wings and BWBs. This study is valuable in that it reveals that L/D_max value can be predicted only with aspect ratio, gross weight (W_g) and wing area (S_wing) data.

中文翻译：

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直接计算润湿面积和最大升阻比的理论模型建议

目的

由于通过实验方法测量飞行性能需要大量的精力和成本，理论模型可以为飞机设计带来新的视角。本文旨在提出一种直接计算润湿面积和 L/D _{max 的模型}。

设计/方法/方法

模型基于这样的想法，即润湿面积与飞机总重量的 2/3 次方 (W _g ^2/3 )成正比。这种方法的空气动力学基础是基于平方-立方定律和寄生阻力与 S_湿/S_翼相关的说法。Raymer 提出的方程用于根据计算出的润湿面积找到 L/D_最大值估计值。理论方法的准确性是通过比较将L测量/ d_最大值在参考文献和L / d发现_最大通过理论方法预测值。

发现

建议的理论 L/D_最大值估计与不同类型飞机的实际 L/D_最大值数据相匹配。在传统的管翼设计中，只有滑翔机的 S_湿/S_翼非常低。飞翼、混合翼体 (BWB) 和大三角翼的 S_湿/S_翼低于传统的管翼设计。较低的相对润湿面积（S_湿/S_翼）是高 L/D_最大目标设计的关键设计标准。

原创性/价值

所提出的模型可用于根据飞机设计中的目标 L/D_最大值确定机翼尺寸。该方法可用于估计不同毛重对 L/D _{max 的影响}。此外，该模型有助于异常设计的 L/D _max估计，例如可变后掠翼、大三角翼、飞翼和 BWB。这项研究的价值在于它揭示了 L/D_最大值只能通过纵横比、总重 (W _g ) 和机翼面积 (S _wing ) 数据来预测。