China
Africa
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Parachutes and Parafoils in Agricultural Crop Production
Published in K. R. Krishna, Aerial Robotics in Agriculture, 2021
Parachutes have been used extensively for airdrop of personnel and cargo, by the military establishments of different nations and humanitarian agencies. As stated earlier, the two most common types of parachutes used are round parachutes and rectangular shaped parafoils. The circular parachutes capture air and that provides a drag force to decelerate a payload and achieve steady descent velocity. The latter, i.e., parafoil, by virtue of its design with air inflated air-foil shaped cells, provides a lift force as well as a drag force. Therefore, parafoils can be steered to deliver payloads accurately, on the ground. Based on this capability, parafoils are currently actively pursued by the military for precision aerial delivery of cargos. The development and introduction of ram-air parachute (parafoil) with facility to steer it and control its rate of descent is an important event. It induced great interest in cargo transport and airdrop. Further, during recent years, GPS-guided transport using sophisticated electronic and computer-based commands has allowed for greater accuracy, Particularly, during airdrop and landing of parafoils (Yakimenko, 2016). It has been forecasted, that, in due course, precision air drop of large cargo using autonomous parafoils may become common.
Effect of fabric construction, seam angle, and impact force on the performance of the parachute canopy
Published in The Journal of The Textile Institute, 2023
Gyana Ranjan Behera, Monica Sikka, Arunangshu Mukhopadhyay
The seam angle is the most influencing and highest contributing factor of the parachute fabric specimen under impact load, as given in Table 2. Moreover, the effect of dead weights on peak extension and total impact duration is the most important aspect of characterising the parachute canopy in the current small-scale impact testing. In this context, the dead weight can be related to the payload of the actual parachute. Thus, the graphical representation of dead weights vs peak extension and total impact duration is plotted in Figure 10. As seam damage in the form of contraction occurs at the seam line of 0° seam angle specimen (Figure 8) and a part of the impact force is dissipated which results in no such significant difference in total impact duration and peak extension with an increment of dead weight (3, 3.25, and 3.5 kgf). However, in the case of the 45° seam bias angle, the specimen shows an increment of peak extension and impact duration with dead weights but there is a sharp difference between the effect by 3 kgf and 3.5 kgf deadweight compared to 3 kgf and 3.25 kgf. Therefore, the % contribution of dead weights varies on change in impact duration and extension, as shown in Table 4.
Multivariate Design of Experiments for Engineering Dimensional Analysis
Published in Technometrics, 2020
Daniel J. Eck, R. Dennis Cook, Christopher J. Nachtsheim, Thomas A. Albrecht
A compelling MIT instructional video1 demonstrates how NASA used DA to compute the diameter of the parachute that would be required to slow the landing of the Mars rover to the desired velocity of 90m/s. The response variable, velocity, can be modeled as a function of four independent variables: the diameter of the parachute, the mass of the rover, gravitational acceleration, and the density of the atmosphere. There are three base quantities involved in this formulation: length, L, mass, M, and time, T. A base quantity such as mass can be measured in different units, such as pounds or kilograms, but in either case the base quantity is mass. A derived quantity of the first kind is a quantity that is constructed from products of powers of base quantities. Velocity is a derived quantity of the first kind because its dimension is . Following standard practice, we write to denote that the fundamental dimension of velocity is .
Measuring and comparing in-situ CO2 and CO profiles with satellite observations and model data
Published in Atmospheric and Oceanic Science Letters, 2019
You YI, Yi LIU, Zhaonan CAI, Shuangxi FANG, Dongxu YANG, Yong WANG, Miao LIANG, Bo YAO, Qianli MA, Maohua WANG
Aircore, which was first proposed and designed by Pieter Tans (2009) at the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, is an innovative atmospheric sampling system. It consists of a long coil of stainless steel tubing. The top left panel of Figure 1 presents the basic Aircore concept. Aircore ascends on a helium balloon and collects samples of the surrounding atmosphere during a parachute-controlled descent. Sample collection commences after separation from the balloon (up to 25 km). An Aircore sample can be analyzed using a continuous trace gas analyzer in a mobile laboratory. The long tube and short time between sampling and analysis minimize mixing inside the tubing, so that each Aircore sample can provide up to 100 measurements of CO2, methane (CH4) and CO between the altitude reached and the ground. Aircore can capture a continuous profile with low cost at vertical resolutions from 500 m to 5 km. High resolution using a lighter Aircore device, especially in the upper troposphere–lower stratosphere (UTLS) region, has been established by NOAA, Groningen University, and Goethe University Frankfurt. Andersen et al. (2018) used an unmanned aerial vehicle to carry the Aircore, and Mrozek et al. (2016) designed an air sub-sampler that can collect and preserve the sample collected from the Aircore for the analysis of isotopes.