ESTIMATION OF THE ULTIMATE LANDING SPEEDS TAKING INTO ACCOUNT THE DEGRADATION OF THE STRENGTH CHARACTERISTICS OF PARACHUTE DOME MATERIALS. PART 2. DEPENDENCE OF THE ULTIMATE LANDING SPEEDS ON THE STRENGTH DEGRADATION
Part 2 is a continuation of Part 1 [1], which proposed the dependence of the maximum permissible loads on the parachute on the degradation coefficients of the power structure elements strength characteristics. The condition of equality of safety factors for elements after the long-term operation and...
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| Format: | Article |
| Language: | English |
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National Aerospace University «Kharkiv Aviation Institute»
2019-04-01
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| Series: | Авіаційно-космічна техніка та технологія |
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| Online Access: | http://nti.khai.edu/ojs/index.php/aktt/article/view/675 |
| Summary: | Part 2 is a continuation of Part 1 [1], which proposed the dependence of the maximum permissible loads on the parachute on the degradation coefficients of the power structure elements strength characteristics. The condition of equality of safety factors for elements after the long-term operation and during design was adopted. The results of calculating the speeds and loads on the parachute were compared with published experimental data. In particular, for the rescue parachute, calculations were made of the fall rate at the moment of the beginning of filling the dome and the maximum load, depending on the aircraft speed. The fall rate is calculated numerically using the motion equations of the dummy-parachute system with given initial conditions. This speed almost coincides with that measured experimentally. Quite satisfactory coordination takes place and for the maximum load. In accordance with the methodology, N. A. Lobanov maximum load depends on the speed at the time of the parachute full opening. This speed is largely determined by the value of the empirical generalized coefficient K. The numerical value of K should be found for a particular parachute from the condition of matching the calculated and experimentally measured loads. The analysis of maximum landing speeds flight limitations from the degradation coefficients of the structural materials strength characteristics was carried out for two cases. The first corresponds to the constancy of the time of separation from the aircraft until the introduction of the parachute dome into operation. The second corresponds to the accounting for the dependence of this time on the aircraft speed. Calculations of the dependence of the maximum allowable aircraft speed on the degradation coefficients were performed in the widest possible range of the generalized coefficients K variation for the dome and lines fabric. The spare Z-5 and landing D-5 series 2 parachutes are considered. The dependences of the maximum permissible landing speeds on the strength degradation coefficients of the framework elements of these parachutes have been established. The actual value of these coefficients must be established by means of destructive strength tests |
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| ISSN: | 1727-7337 2663-2217 |