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Identification of a degradation of aerodynamic characteristics of a paraglider due to its flexibility from flight test

Robert Kulhánek (Department of Aerodynamics Vyzkumny a Zkusebni Letecky Ustav, Prague, Czech Republic)

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 9 January 2019

Issue publication date: 15 August 2019

Abstract

Purpose

Aerodynamics of paragliders is very complicated aeroelastic phenomena. The purpose of this work is to quantify the amount of aerodynamic drag related to the flexible nature of a paraglider wing.

Design/methodology/approach

The laboratory testing on scaled models can be very difficult because of problems in the elastic similitude of such a structure. Testing of full-scale models in a large facility with a large full-scale test section is very expensive. The degradation of aerodynamic characteristics is evaluated from flight tests of the paraglider speed polar. All aspects of the identification such as pilot and suspension lines drag and aerodynamics of spanwise chambered wings are discussed. The drag of a pilot in a harness was estimated by means of wind tunnel testing, computational fluid dynamics (CFD) solver was used to estimating smooth wing lift and drag characteristics.

Findings

The drag related to the flexible nature of the modern paraglider wing is within the range of 4-30 per cent of the total aerodynamic drag depending on the flight speed. From the results, it is evident that considering only the cell opening effect is sufficient at a low-speed flight. The stagnation point moves forwards towards the nose during the high speed flight. This causes more pronounced deformation of the leading edge and thus increased drag.

Practical implications

This paper deals with a detailed analysis of specific paraglider wing. Although the results are limited to the specific geometry, the findings help in the better understanding of the paraglider aerodynamics generally.

Originality/value

The data obtained in this paper are not affected by any scaling problems. There are only few experimental results in the field of paragliders on scaled models. Those results were made on simplified models at very low Reynolds number. The aerodynamic drag characteristics of the pilot in the harness with variable angles of incidence and Reynolds numbers have not yet been published.

Keywords

Acknowledgements

This work was realized, thanks to the grant of the Ministry of Education, Youth and Sports of the Czech Republic nr. SGS16/070/OHK2/1T/12.

Citation

Kulhánek, R. (2019), "Identification of a degradation of aerodynamic characteristics of a paraglider due to its flexibility from flight test", Aircraft Engineering and Aerospace Technology, Vol. 91 No. 6, pp. 873-879. https://doi.org/10.1108/AEAT-06-2018-0162

Publisher

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Emerald Publishing Limited

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