Introduction MAAT cruiser/feeder airship system is a transport system financed by European 7th Framework programme 2011. The project aims to realize a cruiser/feeder airship system, which can connect major populated centres worldwide. The MAAT cruiser feeder system is based on two different airships, the cruiser, which remains airborne for long times, and the feeder, which connects the cruiser with the ground and vice versa. This paper traces a detailed bibliography about MAAT project showing the actual state of the art of the project. This bibliographic review allows understanding the level of innovation related to this project.
Methods Starting from the results of the preceding literature, the authors present a model of the cruiser, in terms of both mass and energy. According to the preceding studies, they have assumed the following minimal set of hypothesis: the buoyant gas is hydrogen; the shape of the cruiser is a discoid; operative altitude is in the range 15-17 km. It is well known that the major showstopper to actual diffusion of airships is related to the initial costs related to the use of Helium.
The problem is more accentuated in Europe than in USA and Russia, because of higher unitary prices. An economic comparison with the possibility of using Hydrogen has produced. A further comparison has performed in terms of operations, focusing on the necessity of replacing the gas, which disperses in the external atmosphere because of the porosity of the tissues of the balloon system. The on board generation of hydrogen as an energy system is very convenient on long permanence airships because the replacement buoyant gas can be produced on board. It has been also traced a complete energy balance of the cruiser airship assuming it as discoid. On one side it has been evaluated the hydrolysis process against batteries showing that an hydrolyser/fuell cell cycle has a lower efficiency in comparison of batteries but it looks less expensive and presents a lower weight than any battery type.
Results This paper has clearly demonstrated that the use of hydrogen is much more convenient than the uoiuse of Helium, even if it require an accurate design to minimize the risks related to hydrogen potential flammability. It demonstrates the necessity of using hydrogen as buoyant gas in long endurance airships because of the easiness of replacement. An estimation of the necessary energy requirements for a discoid airship has produced demonstrating clearly that a discoid shaped airship is energetically inefficient. These results force to consider a different and more efficient cruiser system. MAAT, Multibody Advanced Airship for Transport, aims to investigate aerial transportation possibility by airship based cruiser-feeder system ,.
MAAT is composed by two modules: The cruiser, named PTAH, (acronym of Photovoltaic Transport Aerial High altitude system); the feeder, named ATEN (Aerial Transport Elevator Network feeder), is a VTOL system (Vertical Take Off and Landing) which ensure the connection between the cruiser and the ground. They can lift up and down by the control of buoyancy force and displace horizontally to join to cruiser. This project has started by a preliminary conceptual design activity. The historical milestone references for any author who approaches the design of airships are certainly Lewitt and Warner. Kreider has defined the most comprehensible mathematical modeling of an High Altitude Balloon and allowed to predict the Performance during flight.
The fundamental guidelines about airship designs has synthesized by Khoury and Gillett. The actual aeronautic guidelines has been defined by Raymer , with the conceptual design for innovation method. This methodology can be partially reassumed by the acronym KISS that means “keep it simple, stupid”.
It is not a simple joke. In any breakthrough innovation it is important to adopt a step by step design starting from very basic model and then introducing individual modification, which can be tested individually inside the system. The intrinsic difficulties related to the project has forced to produce a large conceptual and design innovation in different field starting from the basic principles. Krausman has investigated various parameters affecting altitude performance of tethered aerostats. Colozza have studied several models of high altitude airships. In particular he has investigated the possibility of realizing high altitude photovoltaic airships. This studies has inspired the PSICHE project about photovoltaic energy production and conversion at high altitude , and the energetic design based of high-altitude airships by Dumas.
PSICHE can be considered the original cruiser/feeder high altitude system which has been the origin of the MAAT project constituted by two very specialized systems. The cruiser needs to be designed an airship with cruising capability, while the feeder is conceived by simplicity as an aerostat with possibility of control by propulsion. Cyberlink power media player keygen generator. Similar results has been produced by Aglietti and others , who have studied the feasibility of solar power generation using high altitude platforms. Dumas and Trancossi has formulated an improved mathematical model used for PSICHE energetic evaluation, estimating the photovoltaic energy, which can be produced at high altitude by an horizontal photovoltaic plant, both in terms of electric energy or hydrogen and oxygen. In particular this method has been also recently improved by a more complete estimation of the plants and their energetic effects on the system.
Pascoa has produced an effective analysis of possible propulsion concepts which can be adopted on unconventional airships defining an effective state of the art which can be starting point for future development of future airship design modes. Trancossi and others has presented a variable shape airship configuration, which permits to reduce both the risk of fire and presents also a variable frontal section increasing volume with altitude, such as a traditional aerostat.
Dumas and others have presented two different studies on this airship concept, verifying also its optimal mission profile and its feasibility. The difficulties related to the energetic balances related to unconventional high altitude airships has been analysed by Pshikhopov and confirmed by Dumas and Khoshnoud ,. The exigency of producing an effective optimization of the plants and the consequent design guidelines have been demonstrated by Smith ,. This problematic part of the project has been an exceptional opportunity for the future of the project development opening the road to a series of methodological innovations. Two directions has then started: a traditional disciplinary process which aims to improve the results on the basis of specific disciplinary needs which has been produced an interesting series of minor improvements starting from the very interesting stability analysis by Voloshin.
Neydorf has analysed the Stability issues of MAAT feeder airship during vertical movements with wind disturbances. Pshikhopov has considered planning of energy-efficient trajectories for the feeder with implementation of evolution algorithms. Vizinho has performed an effective computational analysis of the propulsive nacelle which needs to be used for the MAAT cruised propulsion. Vucinic, Gaviraghi and others have analysed in depth the connection system and passenger exchange modes between cruise and feeder. Another direction of development of the project is looking at methodological issues such as optimization systems. Ceruti is analyzing multi-disciplinary design optimization with Heuristic Algorithms. Cerruti analyses also how to apply innovatively rapid prototyping tools to facilitate wind tunnel testing of unconventional unmanned airships.
Tuveri is developing an innovative mesh based approach for the estimate the added masses to an unconventional unmanned airship. On the other side Trancossi has focused on the conceptual design methodologies to perform an effective system design optimization. Starting from the generalized formulation of the second principle defined by Adrian Bejan and defined Constructal Law , , he have developed a novel design method which can overcome the theoretical limits of the bottom-up design approach. He has finally proposed final formulations based on a dual cycle design method with a preliminary design method: the first aims to the definition of the optimal system on the basis of Constructal principle and second principle of Thermodynamics, the second aims to produce an effective optimization of the internal subcomponents of the system. This design methodology - defined Constructal Design for Efficiency – aims to finalize an optimal design which can solve the energetic issues related to the MAAT cruiser-feeder system. It has been previously applied to transport airship shapes with interesting results and on MAAT system ,.
In particular, Trancossi is also working inside standardization committees on photovoltaic focusing on the characterization of photovoltaic modules for extreme conditions. 3 Hydrogen use as buoyant gas. The use of hydrogen as buoyant gas is a defined technical choice of the MAAT project. This technical choice is necessary especially for airships with a long airborne permanence, because of simple replacement of the gas which disperses into the environment.
It is possible to evaluate the convenience of hydrogen use both as buoyant gas and as energy storage system comparing it to helium and batteries for a large electrically propelled airship. It has been considered a high altitude long permanence airship, which is a part (cruiser) of the MAAT cruiser-feeder architecture. Three phenomena have considered initial volume inflating (at ground), energy production and storage, gas replacement during service. It has been also evaluated the energy balance of the system for the initial reference discoid shape.
Safety considerations has been also taken into account. 4 General data. Altitude Temperature Pressure Density Pressure H2 m K Pa kg/m3 Pa 0.00 225.00 1.2250 1063.00 24.57 1.1116 943.00 25.22 1.0065 834.00 28.54 0.9091 736.00 20.24 0.8191 647.00 29.91 0.7361 567.00 21.03 0.6597 495.00 20.74 0.5895 431.00 29.81 0.5252 373.00 22.46 0.4663 3220.00 26.27 0.4127 2770.00 22.06 0.3639 2370.00 20.41 0.3108 2020.00 20.41 0.2655 1730.00 21.80 0.2268 1480.00 24.57 0.1937 1260.00 27.46 0.1654 1080.00 2.68 0.1413 9226.02. Number of persons Mass (kg) Passengers 480 48000 Crew 20 2500 Freight 12000 Total passengers and freights 62500 Structure 150000 Energy conversion 60000 Energy storage 50000 Propulsion 40000 Total System Weight 300000 Total Weight 362500 Both Hydrogen and Helium balloons has been estimated and it has been observed that helium balloons results about 1.084 times larger than hydrogen ones. The hydrogen mass has also been evaluated in 29.44 tons while helium mass in about 61.53 tons. A parameter, defined V eff, has defined for hydrogen and helium airships.
It considers that the external volume of the system is larger than the volume of gas strictly necessary for buoyancy. A coefficient 1.1 has adopted in this evaluation because of the system is a cruiser/feeder.
It presents more empty spaces than any other traditional airship system because of this architecture. Altitude Density H 2 Density He V(H 2) Veff (H 2) V(He) Veff (He) m kg/m3 kg/m3 m3 m3 m3 m3 0.00 0.08953 0.51 350 3.00 0.08125 0.06 348 4.00 0.07356 0.61 400 4.00 0.06644 0.76 421 5.00 0.05987 0.37 565 5.00 0.05380 0.78 542 6.00 0.04821 0.21 671 7.00 0.04308 0.13 710 7.00 0.03838 0.81 825 8.00 0.03408 0.07 9 10000.00 0.03016 0.
10190 11000.00 0.02660 0.6 11710 12000.00 0.02272 0.1 13629 13000.00 0.01940 0.0 15939 14000.00 0.01657 0.7 18029 15000.00 0.01415 0.2 21363 16000.00 0.01209 0.1 25716 17000.00 0.01033 0.9 30323. The initial inflation can be evaluated by assuming the masses of both helium and hydrogen. In 2011, the Helium 99.9% the average market price in the U.S. can be estimated between 50 and 70 USD/MCF. It means a price between 1.77 and 2.47 USD/m 3. For such a volume of hydrogen it is necessary an initial expense between 613000 USD and 855000 USD excluding losses.
Some China suppliers have similar prices also. The marketing audit comes of age pdf. Prices exclude storage cylinders and delivery costs, which lead in Europe to much higher prices.
In a preceding paper, Dumas has estimated that the necessary hydrogen can be produced in one year with a large photovoltaic facility with the characteristics reported in Table. It has evaluated the economic feasibility of photovoltaic hydrogen production that making a conservative hypothesis on the prices of hydrolytic hydrogen (evaluated one-fifth of average helium cost). For advanced solid polymer or alkaline electrolyser, the electric efficiency of the industrial process overcomes 75%. Module Properties poly-Si Module Unit Value Power capacity W 200 Efficiency% 13.50% Area m 2 1.48 Nominal operating cell temp. °C 45 Temperature coefficient%/°C 0.40% Plant and Conversion Properties Plant Unit Value Miscellaneous losses% 5.00% Inverter Unit Value Efficiency% 95.00% Capacity kW 1 Distribution Losses% 5.00% A possible market price of hydrogen for airship inflation can be estimated (prudentially) the 25% of average helium cubic meter prices. It means that a cubic meter of Hydrogen is about 0.5 $/m 3 (a low price considering actual market standards).
Considering that about 5 kWh are necessary to produce 1 m 3 of compressed hydrogen, it means the price of electricity can be considered 0.1 $/kWh. (4)where E p is the activation energy of permeation, E d the activation energy of diffusion, and E s the heat of solution that have in SI units the dimension kJ/mol. Those data are tabled for many polymers and for many gasses and liquids.
P o, D o and S o are the multiplicative factors. R is the gas constant; T is the temperature. The permeability coefficient is determined for a given temperature by means of the multiplicative factor P o and the activation energy of permeation E p. These data have been tabled by Pauly. (5) Gas dispersion for the three critical gasses has calculated for 1 m 2 of balloon surface and per hour of steady service.
The choice of material must be a good compromise of mechanical properties and gas dispersions. The best compromise solutions between mechanical properties and porosity are Mylar A and or Nylon rip-stop-polyurethane dual layer balloons. It is possible to find on the market high-quality proprietary fabrics. For example, it can be cited 3-ply rip-stop nylon 108.5 g/m 2 made on rigorous standards with internal polyurethane balloon. It has not the typical problems of the polyurethane: the pinholes and the difficulties in reparation. This material allows evaluating daily losses in STP conditions.
Helium losses are about 2.5 10 −4 m 3 (273.15 K; 1,013 × 10 5 Pa)/(m 2 day). Hydrogen losses about 3.5 10 −4 m 3 (273.15 K; 1,013 × 10 5 Pa)/(m 2 day). The cited values do not consider an entire airship in service including losses due to the junctions among different textile sheets (Blimpworks Airship – USA). The considered overpressure is higher than the usual one 1–3%). 8 Gas dispersion evaluation in service. Another important volumetric effect is the daily thermal excursions and to location changes during travel. They have, with solar irradiance, large effects on the temperature and density of the buoyant gas.
To compensate these daily thermal effects is necessary to preserve the operative altitude. The reference temperature of Standard Atmosphere model at stratospheric altitudes is about −56 °C. The simplest regulation of the volume against temperature variations is to vary the mass of gas in the balloon. The same pressure and volume preceding the thermal variation can be restored and preserved. Thermal controls have often used but volumetric are less expensive and less complex.
They need only a sufficient reserve of gas.
Key people Philip Gwyn Stephen McGlennan Products Airlander 10 Website Hybrid Air Vehicles Limited is a British manufacturer of. These aircraft use both aerodynamics and (LTA) technology to generate lift, potentially allowing the vehicle to stay aloft for several weeks. The company developed the HAV 3 technology demonstrator.
This won it the US Army LEMV contract, in association with as the prime contractor, and led to the. Following termination of the LEMV project, the HAV 304 was rebuilt as the Airlander 10.
It is the largest aircraft flying today. Main article: HAV is the latest in a line of companies to acquire and develop airship technologies in the UK. Aerospace Developments was formed in 1971 and since then its assets have passed through successive companies Airship Developments, Airship Industries, Westinghouse Airships, Airship Technologies, Advanced Technologies Group (ATG) and, immediately preceding HAV, the SkyCat group which folded in 2007. During this period a number of airships and hybrids were built.
Multi-hull airships Hybrid Air Vehicles was formed in 2007 by Roger Munk. It acquired the assets of the SkyCat group and established itself at, UK. The company developed the HAV 3 technology demonstrator. In partnership with (NGC) as prime contractor, in 2009 it won a US$500 million US Army contract to develop a (LEMV), which was delivered between 2009 and early 2013. Hybrid Air Vehicles designed, developed and manufactured the aircraft for the LEMV project, with NGC acting as the prime contractor and sensor system integrator. On 7 August 2012 a successful 90-minute test flight took place in,. The LEMV project was cancelled In February 2013.
Hybrid Air Vehicles took the opportunity to buy back the envelope and associated materials, which they returned to the UK for conversion to the civilian. In 2014 it was unveiled in. It is reported as the world's largest aircraft. One investor, (better known as a member of the heavy metal group ), has announced plans to fly twice around the world nonstop. Aircraft.
Main article: Following cancellation of the LEMV project, HAV bought back the HAV 304, returned it to the UK and converted it for civilian use as the Airlander 10. Airlander 10 is 92 metres (302 ft) long, 44 metres (144 ft) wide, and 26 metres (85 ft) high. The Airlander 10 landed nose-down on 24 August 2016 during its second test flight on the Cardington airfield in Bedfordshire, causing damage to the cockpit. Repairs were completed by February the following year and the Airlander recommenced its flight test programme on 10 May 2017. Airlander 50 The Airlander 50 is a proposed larger transport craft with a 50 tonne payload. References., BBC, 4 January 2011.
Today, they continue to write, produce and perform concerts, mentor other gifted newcomers, and otherwise continue to leave their indelible stamp on the music industry. The best of yarbrough and peoples rar. They married in on January 18, 1987, and tiring of the Southern California grind, returned to their hometown of Dallas and started their own music production company, Yarbrough & Peoples Productions.
Extract from a post. Hybrid Air Vehicles. Retrieved 17 December 2011. Service, Army News. Retrieved 2016-03-30.
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Airship Technology Group
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