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Balloons and Airships
Published in James DeLaurier, Aircraft Design Concepts, 2022
Another type of free balloon is the hot-air design, which has been popular for sport ballooning since the 1970s. In this case the “lifting gas” is heated air, because it has a lower density than the surrounding atmosphere. Buoyancy control is provided solely by a propane burner, which controls the temperature of the hot air. No ballast or venting is required, and the balloon can fly until the propane is expended. Hot air doesn't have the same lifting capability as helium or hydrogen, but the convenience and inexpensiveness of operation more than make up for this. It should be observed that aerodynamics has a very small role to play with these aircraft because a free balloon moves with the wind. This allows hot-air balloons to be shaped into a variety of unique configurations.
Aerostats, Helikites, and Balloons in Agriculture
Published in K. R. Krishna, Aerial Robotics in Agriculture, 2021
In order to conduct the normal floating functions, an aerostat should be equipped with a balloon/envelope. Envelope (i.e., hull) could be of different sizes and shapes. Normally, the lifting gas used is lighter-than-air helium gas. In addition, a tethered aerostat system includes a truck/ or a trailer. This is to transport the envelop (see Plates 4.1 and 4.2). The aerostat system also needs a mooring station when not in use or when we wish to keep it in readiness, for use in the sky. A platform to conduct the lift-off is necessary (Figure 4.1, item 4). A tethered aerostat, as name denotes, has to be equipped with several tethers (strings). The tethers are required to keep the aerostat in place in the sky or to move it across different locations. Tethers are needed to tie it down to a mooring station (see Plate 4.3). Also, most importantly, tethers are used to transmit power and aerial data captured by the sensors placed in the payload area. A tethered aerostat needs winches for letting out, pulling or to apply correct tension of the tethers. We also need devices to deflate the aerostats envelop, whenever it is not in use (Homeland Security, 2017; Altave Inc., 2019a ,b; Airstar Aerospace SAS, 2019a ,b; Allsopp Helikites Ltd., 2019a; SkyDoc Systems INC., 2019; Aeroscraft LLC. 2019).
Design and route optimisation for an airship with onboard solar energy harvesting
Published in International Journal of Sustainable Energy, 2023
Christoph Pflaum, Tim Riffelmacher, Agnes Jocher
The chosen weight of the expected payload is presented as follows. The lifting gas is assumed to be a combination of helium and mainly hydrogen, the way it was originally planned for the LZ 129 (see Kleinheins 1996). The volume of the lifting gas of LZ 129 was 190,000 m3. However, considering the total volume of about 230,000 m3, one can assume that a modern construction allows a lifting gas of 195,000 m3. Using the barometric formula, this leads to a buoyant force that could lift between 189 and 129 t depending on the studied travel altitude between 2000 and 5600 m. Tables 1 and 2 show the corresponding maximal load and the maximal number of passengers. Here, the average mass of baggage is assumed to be 100 kg per passenger plus around 20 kg (ICAO 2009). Furthermore, the weight of the interior design like sleeping cabins is assumed to be 180 kg per passenger, which leads to 300 kg in total per person. The results in Tables 1 and 2 assume conventional buoyant lift. However, modern airship design can aerodynamically attain a significantly higher lift (see Khoury 2012). Therefore, a flight height of 5600 m for 100 passengers might be possible, when additional aerodynamic lift can be achieved.
Tubular polythene film balloons for load lifting in the construction, mining and recreation industries
Published in Australian Journal of Multi-Disciplinary Engineering, 2022
The principal advantage of tubular balloons relative to spherical balloons is that the envelope can be produced, nearly complete, by the blow moulding process in a tube of indefinite length. To complete a tubular balloon and enclose a lifting gas in a tubular envelope the ends of the tube must be sealed and a nozzle fitted at the lower end of the tube for filling with the lifting gas. For small balloons, D = 1.2 m, L = 12 m as in Figure 1, an envelope can be formed by sealing the top end of the tube by knotting the plastic, the envelope is filled with the lifting gas and the lower end of the tube knotted to close the envelope. The load is attached at the lower knot. For larger envelopes, D = 4 m, L > 20 m, sealing the top end of a polythene tube to form an envelope can carried out by methods used the packaging industry. One familiar method useful for larger and heavier grades of polythene tube is to pass the end of the tube between two, constant temperature, Teflon covered, rollers. The width of the seal or weld resulting is typically 10 mm. Several seals of this type side by side would adequately seal the upper end of a tubular balloon, as illustrated in Figure 5.
Ultra-lightweight fiber-reinforced envelope material for high-altitude airship
Published in The Journal of The Textile Institute, 2022
Rahul Vallabh, Ang Li, Philip D. Bradford, David Kim, Abdel-Fattah M. Seyam
Helium is preferred choice for the lifting gas to provide buoyancy retention, however due to the small size of the molecules; He has high transverse permeation rates through laminates. Helium permeability of laminate prototypes EP-1 and EP-4 were measured 8.0 and 0.4 cc/m2.24 hr.1 atm, respectively. For a 75 m long airship with a maximum diameter of 18 m, the above helium permeability values translate to less than 0.1% helium loss for a flight duration of 1 year. The significantly lower permeability value of EP-4 is attributed to the use of double-sided VDA coating of PI film (compared to the single-side coated PI film in case of EP-1), thicker VDA coated Mylar® film, and thicker EVOH film as the adhesive layer. Due to presence of similar weather protective layer, adhesive layer, and helium barrier layer, helium permeability of EP-2 and 3 are expected to be close to that of EP-1. The only published data is by Cao and Gao (2009) who reported the helium permeability of a 230 gsm laminate as 115 cc/m2.24 hr.1 atm, which is significantly higher than that of laminate prototypes EP-1, 2, 3 and 4. Another published work (Kang et al., 2006) has stated that for a 200 m long by 50 m diameter airship, the helium permeability should be less than 2000 cc/m2.24 hr.1 atm, however, the basis for the stated requirement is not clear.