The Influence of Errors of Atmosphere State Determination on the Object’s Landing Velocity

• Main Authors: Yu. Adamov, O. Dyachenko, V. Zavalniuk
• Format: Article
• Language: English
• Published: LLC Production and Commercial Company «FAVOR, LTD» 2017-09-01
• Series: Метрологія та прилади
• Subjects: parachute-retrorocket system, terminal velocity of landing, landing velocity, atmospheric pressure
• Online Access: https://mmi-journal.org/index.php/journal/article/view/113
• ISSN: 2307-2180; 2663-9564

The influence of the atmospheric state (air temperature, pressure, humidity and vertical air flow velocity) on the performance of parachute-retrorocket system 915 (PRS-915), used for vehicle airdropping operations, is studied. Particular emphasis is placed on the effect of atmospheric state determination errors on the vehicle vertical landing velocity. It is shown that the account of these errors is important for setting the PRS’ ground seeking probes to the appropriate length and provides the basis for an additional improvement of safety and efficiency of the vehicle airdrop missions using PRS-915 [1—4]. The optimal altitude of retrorocket ignition depends on the weight and descent velocity of the load, and the retrorocket engine thrust. The descent terminal velocity is determined by the geometrical parameters of parachute and the weight of vehicle, air density and vertical air flow velocity (1), (2). The probes’ length required for the soft landing is usually determined on the basis of prediction of atmospheric state in the mission region. The errors of such a prediction may lead to substantial difference between the predicted and actual landing speed and, as a result, to hard landing of the object (4), (5). The dependence of actual landing speed on the errors of determination of atmosphere pressure and temperature in the landing area (7), (10) is obtained. It is shown that the presence of even small errors in temperature and pressure prediction may result in exceeding of the permissible limits of landing speed. The situation is essentially aggravated by the presence of other possible errors or strong vertical air flows. As a result, the development of new methods of retrorocket engine launching at optimal altitude, which eliminate the need for advance prediction of the atmospheric state, is extremely actual for reliability and safety improvement of parachute-retrorocket systems.