Purpose

Blended wing body (BWB) is a very advantageous design in terms of low fuel consumption, low emission and low noise levels. Because of these advantages, the BWB is a candidate to become the commercial passenger aircraft of the future by providing a paradigm shift in conventional designs. This paper aims to propose a key design parameter for wing sizing of subsonic BWB and a performance parameter for calculating the lift/drag ratio values of BWBs.

Design/methodology/approach

The parameter proposed in the study is based on the square/cube law, that is, the idea that the wetted area is proportional to the power of 2/3 of the weight. Data on the weight, wing area, wingspan, lift-to-drag (L/D) ratio for 19 BWB used in the analyzes were compiled from the published literature and a theoretical methodology was developed to estimate the maximum lift to drag ratio of BWBs. The accuracy of the proposed key design parameter was questioned by comparing the estimated L/Dmax values with the actual values.

Findings

In the current study, it is claimed that the wingspan/(take-off gross weight)^(1/3) parameter provides an L/D efficiency coefficient regardless of aircraft size. The proposed key design parameter is useful both for small-scale BWB, that is unmanned aerial vehicles BWB and for large-scale BWB designs. Therefore, the b/Wg^(1/3) parameter offers a dimensionless L/D efficiency coefficient for BWB designs of different scales. The wetted aspect ratio explains how low aspect ratio (AR)-BWB designs can compete with high AR-tube-and-wing designs. The key parameter is also useful for getting an idea of good or bad BWB with design and performance data published in the literature. As a result, reducing the blending area and designing a smaller central body are typical features of aerodynamically efficient BWB.

Originality/value

As the role of the square/cube law in the conceptual aircraft design stage has not been sufficiently studied in the literature, the application of this law to BWBs, a new generation of designs, makes the study original. Estimation of the wetted area ratio using only wingspan and gross weight data is an alternative and practical method for assessing the aerodynamic performance of the BWB. According to the model proposed in the current study, reducing the take-off gross weight of the BWBs using lighter building materials and designing with a larger wingspan (b) are the main recommendations for an aerodynamically efficient BWB.

中文翻译：

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气动高效亚音速混合翼体的关键设计参数建议

目的

融合翼体（BWB）在低油耗、低排放和低噪音方面是一种非常有利的设计。由于这些优势，BWB 通过提供传统设计的范式转变，有望成为未来的商用客机。本文旨在提出亚音速 BWB 机翼尺寸的关键设计参数和计算 BWB 升阻比值的性能参数。

设计/方法/方法

研究中提出的参数基于平方/立方定律，即润湿面积与重量的 2/3 次方成正比的想法。分析中使用的 19 BWB 的重量、机翼面积、翼展、升阻比 (L/D) 数据来自已发表的文献，并开发了一种理论方法来估计 BWB 的最大升阻比. 通过将估计的 L/Dmax 值与实际值进行比较，提出的关键设计参数的准确性受到质疑。

发现

在当前的研究中，据称翼展/（起飞总重量）^（1/3）参数提供了 L/D 效率系数，而与飞机尺寸无关。所提出的关键设计参数对于小型 BWB（即无人机 BWB）和大型 BWB 设计都是有用的。因此，b/Wg ^(1/3)参数为不同规模的 BWB 设计提供了无量纲的 L/D 效率系数。湿纵横比解释了低纵横比 (AR)-BWB 设计如何与高 AR 管和翼设计竞争。关键参数还有助于通过文献中公布的设计和性能数据了解 BWB 的好坏。因此，减少混合区域和设计更小的中心体是空气动力学高效 BWB 的典型特征。

原创性/价值

由于平方/立方定律在概念飞机设计阶段的作用尚未在文献中得到充分研究，将该定律应用于新一代设计 BWB，使研究具有独创性。仅使用翼展和总重量数据估计湿面积比是评估 BWB 空气动力学性能的一种替代且实用的方法。根据当前研究中提出的模型，使用更轻的建筑材料减少 BWB 的起飞总重量并设计更大的翼展 (b) 是空气动力学效率 BWB 的主要建议。