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The purpose of this paper is to describe the results of investigations of parachute rescue systems (PRS) for light gyrocopters.

Although the investigations were conducted in both stages simultaneously, i.e. experimental mechanics approach and numerical simulations, the paper is focussed mainly on the experimental part of the work. To ensure the safety of experimental works (i.e. for both experimenters and bystanders), the authors applied unmanned, remotely controlled scale models of autogyro for the PRS testing in the air.

The critical problem for successful use of the PRS is that the rotation of the rotor blades must be stopped when the main parachute opens, otherwise the influence of the rotor on the improper opening process of the parachute may cause the whole PRS to become useless.

The existing regulations for the use of unmanned aircraft impose the limitation upon the organisation of in-flight tests of PRS, i.e. the maximum take-off mass of the tested gyrocopter models is limited, and a full-scale test needs the approval of European Aviation Safety Agency (EASA).

The research contributes to increasing the safety level for gyrocopter users. The authors elaborated the original PRS, which currently is in the process of patenting.

Originality of the work consists of both an innovative PRS, which has never been tested before, and the results of experimental investigations, which cover both ground tests carried on static or moving stands and in-flight testing.

The purpose of this paper is to present the concept of the author’s method of fatigue properties assessment of polymer composite structures, especially structures having nodes of concentrated force introduction (NCFI) using fatigue test data of coupons of similar composites and the ratio of their structural stress rate factors.

Basing on fatigue properties of pure composite shells coupons subjected to cyclic loads, and basing on the static strength difference between pure composite shells and shells having the structure affected by NCFI – (considered here as not only a manner of load introduction but also a kind of structural discontinuity), a method of relative fatigue properties reduction (RFPR) was developed. In the RFPR evaluation process, the author used the results of experiments on a special type of an NCFI named “a labyrinth non-adhesive node of concentrated force introduction” (LNA-NCFI) applied in certain composite gliders for fitting glider wings with the fuselage and also referred to design directives relating to primary structure of composite gliders, which are presented in the form of lightness factors linking stress with a structural mass.

The result of RFPR method application matched well with the results of fatigue tests of the LNA-NCFI type of a NCFI. The RFPR method may significantly facilitate the estimation of fatigue life of a structure with a structural discontinuity or an NCFI.

The RFPR method may significantly facilitate the estimation of fatigue life of a structure with a structural discontinuity or an NCFI.

The paper presents a proposal of a novel simplified method for fatigue life estimation of composite structures having a kind of structural discontinuity or an NCFI.

The purpose of this paper is to present the author’s method of conservative load spectrum (LS) derivation and close-proximity LS extrapolation applying a correction for measurement uncertainty caused by too low sampling frequency or signal noise, which may affect the load histories collected during the flying session and cause some recorded load increments to be lower than the actual values.

Having in mind that the recorded load signal is burdened with some measurement error, a conservative approach was applied during qualification of the recorded values into 32 discrete load-level intervals and derivation of 32 × 32 half-cycle arrays. A part of each cell value of the half-cycle array was dispersed into the neighboring cells placed above by using a random number generator. It resulted in an increase in the number of load increments, which were one or two intervals higher than those resulting from direct data processing. Such an array was termed a conservative clone of the actual LS. The close-proximity approximation consisted of multiplication of the LSs clones and their aggregation. This way, the LS for extended time of operation was obtained. The whole process was conducted in the MS Excel environment.

Fatigue life calculated for a chosen element of aircraft structure using conservative LS is about 20%–60% lower than for the actual LS (depending on the applied value of dispersion coefficients used in the procedure of LSs clones generation). It means that such a result gives a bigger safety margin when operational life of the aircraft is estimated or when the fatigue test for an extended operational period is programed based on a limited quantity of data from a flying session.

This paper presents a proposal for a novel, conservative approach to fatigue life estimation based on the short-term LS derived from the load signal recorded during the flying session.

This paper aims to present the assumptions, analysis and sample results of numerical modeling and analysis of dynamic events encountered in emergency cases during deployment of parachute rescue system (PRS) and hard landing of a small gyrocopter. The optimal design requires knowledge of structural loads and structural response – the information obtained often from experiment. Numerical simulation is presented as an alternative tool for estimating these data.

Structural analyses were performed using MSC.Nastran. Multibody simulations were done using MADYMO system.

Initial design parameters were evaluated and verified in numerical simulations. Some of the resulting conclusions were proven during the test flights.

Some chosen results of simulation of dynamic problems are presented. They can be useful as reference values for similar cases for light aircraft analysis.

The paper presents an alternative way of assessing structural response parameters in the case of emergency dynamic events of usage of PRS. The results can be used in other projects.