Purpose

The purpose of this paper is to improve the design of a solid square canopy of a parachute. The design improvements are brought out by providing minor slits in the canopy area. Proper designing of the parachute was carried out using theoretical investigation coupled with experimentation. This parachute is designed for launch of sonobuoy from fixed wing aircraft.

Design/methodology/approach

Literature review was carried out on the design of such parachutes for the launch of a sonobuoy from a high altitude to the water entry. Computational fluid dynamics (CFD) analysis provided the value of the coefficient of drag for the slit-cut square canopy parachute, with and without sonobuoy for different lengths of the slit. Besides the theoretical investigation, experimentation was also carried out to validate the design.

Findings

The experimentation was carried out on 58 and 75 gsm fabric canopies with the slit edge plain-cut with thermally sealed edges, stitched and strengthened. In the case of plain-cut slits on the canopy made of 75 gsm fabric, no tearing of the slit edge was observed in dynamic and flight tests.

Research limitations/implications

The present work has been carried out considering various assumptions and limited trial data specific to precision drop of 9 kg payload. The work can be adopted for bigger parachute for dropping of higher payloads.

Originality/value

Lab strength test, track dynamic and flight trials were conducted to acquire useful data for the present analysis. Besides the theoretical investigations and CFD analysis inherently based on numerous assumptions, experimentation was carried out as the sonobuoy deployment conditions are full of uncertainty. Dynamic and airdrop tests were conducted for this reason to determine design changes in the slits, both at the material level and on improvisations.

中文翻译：

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基于调查与试验的高空发射空投降落伞设计改进

目的

本文的目的是改进降落伞实心方形伞盖的设计。设计改进是通过在顶篷区域提供小缝隙来实现的。降落伞的正确设计是通过理论研究和实验进行的。这种降落伞是为固定翼飞机发射声纳浮标而设计的。

设计/方法/方法

对这种用于声纳浮标从高空发射到入水口的降落伞的设计进行了文献综述。计算流体动力学 (CFD) 分析提供了狭缝切割方形顶篷降落伞的阻力系数值，对于不同长度的狭缝，有和没有声纳浮标。除了理论研究外，还进行了实验以验证设计。

发现

实验是在 58 和 75 gsm 织物檐篷上进行的，其开缝边缘平切，热封边缘，缝合和加固。在由 75 gsm 织物制成的座舱盖上的平切缝的情况下，在动态和飞行测试中没有观察到缝边的撕裂。

研究限制/影响

目前的工作是考虑到各种假设和有限的试验数据而进行的，这些数据专门针对 9 公斤有效载荷的精确下降。该工作可用于更大的降落伞，以降低更高的有效载荷。

原创性/价值

进行了实验室强度测试、轨道动态和飞行试验，以获得用于当前分析的有用数据。除了固有地基于众多假设的理论研究和 CFD 分析外，由于声纳浮标部署条件充满不确定性，因此进行了实验。出于这个原因，进行了动态和空投测试，以确定狭缝的设计变化，包括材料层面和即兴创作。