IT202100016379A1 - LTA TROPO-STRATOSPHERIC AIRCRAFT WITHOUT HELIUM - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

?LTA TROPO-STRATOSPHERIC AIRCRAFT WITHOUT HELIUM?

The present invention relates to an LTA (Lighter Than Air) aircraft for use in the troposphere and stratosphere which does not require the use of helium gas or other gases or mixtures thereof.

Current Earth observation systems are mainly based on the use of satellites or satellite constellations and on aeronautical platforms. Satellite systems allow you to observe a large portion of the territory but have a revisit time that can vary from a minimum of a few days (also including images obtained with a different angle of view from the nadir) to a few weeks. The spatial resolution depends on the orbit of the satellites. Also, in the case of satellite constellations ? almost impossible, or extremely costly, to carry out maintenance or technological updating of the on-board subsystems and the payload itself. The advantage of satellite constellations ? their long operational life.

Aeronautical platforms, both self-driving and human-guided drones, offer the possibility to embark sensors for Earth observation which, given their proximity to the ground, provide images with a very high spatial resolution but on an extremely small area. The duration of the missions, both due to the duration limits of the energy system in the case of drones and to not excessively increase the pilot's workload for manned aircraft, ? extremely reduced.

Furthermore, the possibility to use aeronautical platforms? subject to the presence of favorable weather conditions.

For some applications of the ISR type (Intelligence, Surveillance, and Reconnaissance), such as for example the control of both sea and land borders, it is necessary a surveillance system that offers coverage of the area of interest continuously for a period of a few months a year. In the case, for example, of the control of the routes traveled by boats carrying illegal immigrants in the Mediterranean Sea, the surveillance system? most requested in the summer, when the sea conditions are favorable for crossing.

For this type of applications, satellite systems offer a revisit time and a resolution that is not ? useful for monitoring the phenomenon of interest, on the other hand it would be unthinkable to have several aircraft in flight continuously to ensure patrolling of the area of interest.

In the case of applications that require the deployment of a protected telecommunications infrastructure in a war scenario, satellite systems and aeronautical platforms are not usable. The first for the costs and for the complexity? of design of a new constellation and deployment that make the process not feasible for a? Need that? limited in space and time; the latter, again, for the reduced endurance.

Therefore, currently not available in the equipment of military systems, a flying platform that has the ability to? to offer coverage, over an area having a regional extension, with a spatial and temporal resolution suitable for ISR applications and which is also easily deployable on site and configurable according to the operational scenario.

The need to obtain an Earth observation and telecommunications system that offers adequate spatial resolution and coverage of the area of interest in a persistent manner finds an answer in the High-Altitude Pseudo-Satellite.

The High-Altitude Pseudo Satellite (HAPS) or Lighter Than Air aircraft are platforms deployed in the Stratosphere, in an altitude range of 15000-20000m, altitudes where the winds are somewhat limited.

Stratospheric platforms represent a new generation of tools capable of detecting in real time and automatically, data and images with modality? which constitute a clear evolution in the framework of Earth Observation (OT) in terms of continuity? of observation, precision and accuracy.

Compared to existing systems such as Aircraft and Satellites, a HAPS unlike satellites can? obtain a greater spatial resolution, and above all compared to satellites LEO allows a very high temporal resolution being able to guarantee a substantial persistence on a local scale (about 800 km<2>).

The advantages of the HAPS platforms have led, over time, to give more and more credit to the possibility of their use as valid complements to satellites and drones.

In order to guarantee the? operation? necessary for the execution of the mission, the HAPS use photovoltaic energy.

Having defined the irradiance, which depends on the position and on the time of year, the photovoltaic system must be able to directly power the load during the hours in which it? irradiated and in pi? it must supply enough energy to charge the storage batteries for the other hours of the day.

The structure of these aircraft can? assume different forms, but all are characterized by the use of gas pi? lighter than air, typically helium, which fill large containers made with very light films, even from a few grams per square metre. The helium or mixtures of it? definitely preferred over hydrogen which shows a very high flammability risk.

AND? while it is true that the world is facing a severe shortage of helium, which threatens not only the balloon and HAPS industry.

The helium ? an odorless and colorless gas, ? the second element more? abundant in the universe after hydrogen, but isn't it? easy to find or store quantity? usable, most of the helium in the atmosphere escapes into space, and our current supplies of helium are largely extracted from underground natural gas reserves.

The United States is the world leader in helium production, producing approximately 75% of the world's helium. The shortage of this material has led to an increase in the price, currently about three times.

The innovation that we intend to patent involves the construction of light inflatable structures, which do not require the use of helium, and which can withstand a difference in pressure from the outside to the inside, so that the weight of the internal air, resulting lower than the weight of the external air, creates an upward thrust due to the well-known Archimedes principle.

The casing? Made of a high performance non-woven composite material used in high strength, low weight applications. ? consisting of a thin sheet of ultra high molecular weight polyethylene laminated between two sheets of polyester.

The tensile structure (Tab 1, Fig 1) which allows for a closed volume at a pressure lower than atmospheric pressure? made using very light tubes (Tab 1, Fig 1) whose inside? brought to a pressure such as to allow the preservation of the shape of the structure. A possible realization? shown in section in Table 1, Fig 2.

because the density? of the air ? of 1,225 g/l at the typical pressure on the sea level at 15?C that ? 1013.25 mBar, it follows that considering, for example, a sphere with a radius of 5 metres, there is a thrust, as a function of the internal-external pressure difference, shown in the following table:

By increasing the quota, the volume remains almost? the same but decreasing the density? of the external air the aerostatic thrust decreases:

Considering that the material constituting the casing, in this example weighs approximately 10g/m<2 > or 3.14Kg, to which must be added the weight of the tensile structure made with pipes of the same material as the casing estimated at a further 7 Kg, the result is a positive aerostatic thrust upwards already? at very low depressions, at an altitude of 1500 meters with the indicative depression shown in the table, the thrust remains at 42Kg, capable of supporting the payload.

The internal-external pressure difference is achieved on the ground, before launch, by means of suitable external compressors and aspirators, while in flight the pressure difference is maintained and managed by a small electric pump piloted by a microprocessor and powered by a photovoltaic system. During the ascent at high altitude, the pump will have to? gradually reduce more and more the internal pressure and maintain the pressure of the structure at the right level through the pressure pipes.

It should be emphasized that in the following, by way of non-limiting example, only two embodiments of the present invention will be illustrated, with relative calculations, it being possible to describe many others on the basis of the particular technical solutions identified.

Figure 1 shows a possible shape of the aircraft (only the hemisphere is shown for graphical reasons), in which (Tab 1 fig 2) ? the wrap, such as a laminated fabric made of ultra high molecular weight polyethylene in fiber and polyester monofilaments, PVF, film, and more. The piping system (Tab 1 fig 1) ? made with the same material as the outer casing.

The simulations (Tab 2 figs 1 and 2) were carried out with an internal/external pressure difference of 300mBar thus realizing a thrust at sea level of just under 200Kg.

The pump can be of a commercial type, small in size, of the same class as those used to inflate tires in an emergency powered by the car battery. It should be remembered that the ascent flight in the stratosphere still requires a few hours therefore the flow rate of the pump can? be almost negligible.

The second example shown in table 3 can? be considered if you want to maintain an aerodynamic profile of the aircraft. In this case the volume (3) ? the section in depression, spherical or slightly elongated, due to structural limitations cannot? take any form, section (2) ? instead filled with helium under light pressure for self-sustaining, it too contributes to the upward thrust, but the helium content ? very small, this volume pu? assume aerodynamic shapes. Area (4) allows the two casings to be separated at the pressure level. Some details of the aerodynamics are indicated with (5) and (6), while the device (7) contains the payload.

The present invention ? been described for illustrative, but non-limiting purposes, according to some preferred embodiments, but ? it is to be understood that any changes and/or modifications may be made by experts in the sector without thereby leaving the relative scope of protection, so? as defined by the appended claims.

Claims (2)

TITLE: ?LTA TROPO-STRATOSPHERIC AIRCRAFT WITHOUT HELIUM? CLAIMS 1. Tropo-stratospheric helium-free LTA aircraft comprising a spherical or spheroidal structure made of pressure tubes made of a resistant and ultra-light polymeric film, a casing that covers this gas-tight structure made of ultra-light and resistant polymer, a pump such as create sufficient pressure in the tubular structure and a vacuum inside the casing, a photovoltaic system or batteries for powering the pump, a microcontroller for piloting the pump according to the internal, external and pipe pressure. 2. Helium-free tropo-stratospheric LTA aircraft according to claim 1, characterized in that to improve its aerodynamics? can? an aerodynamic envelope must be created which contains the structure (Tav 1 fig 2), only this volume is filled with helium to support itself, to which the tailplanes, the propeller and the payload can be fixed.