Thermal airship

Hot air airships are airships, which receive their buoyancy by the density difference between hot and cold air. They are derived from the technology of the balloons.

  • 4.1 Natural overpressure
  • 4.2 Artificially generated overpressure
  • 4.3 Drive and control
  • 4.4 gondola
  • 4.5 Comparison with gas airships

History of hot air airships

The first hot -air airships, whose lift is generated solely by the heating of the support volume, appeared with the renaissance of hot air balloons in the 1970s. The company Cameron Balloons in England offered the first hot -air airships in the mid- seventies, in addition to the classic hot-air balloons for sale. These early hot -air airships were in principle protracted hot air balloons. Shape and stability has been achieved only through the static pressure of the hot air within the envelope. The burner assembly was mounted as in the balloon below the open bottom shell.

The late seventies, the English company also Thunder & Colt brought a first over -pressure hot -air airship on the market, which was technically superior to the Cameron type. In this development of the envelope pressure is increased with the aid of a blower and stabilized. The burner worked inside the now completely closed shell. The number of airships until the turn of the millennium from both English guy sold worldwide is estimated to be about 100.

Cameron Balloons in Bristol went mid-1980s after the introduction of a separate overpressure types of similar construction. Since the mid- 1990s also Lindstrand Balloons is represented by its own pressure airship type on the market.

As before, there were in the nineties great development potentials. Until the early nineties, no manufacturer had undertaken basic scientific research in the strict classical sense. The development work was limited to the purely practical experimentation and implementation of small-scale flight of subjective experiences of some, less pilots.

It ruled one-to two -seater overpressure types before with a volume of 1,500 to 3,000 m³. The engine power was varied while 18-37 kilowatts ( 25-50 hp). The attainable speeds were about 18 to 28 km / h ( 10-15 kn). The flight times of the standard models of one to one and a half hours. Depending on the suitability of the flight terrain and the professionalism of the team in these on the market hot air airships are used in surface winds of 6 to a maximum of 8 knots (force 2 ). Conventional hot air airships are therefore a piece of weather- sensitive than hot air balloons and have a similar profile as the use of so-called Special Shape balloons ( balloons with envelopes in a special form ).

Thunder & Colt was bought in 1995 by Cameron Balloons.

Development in Germany

Based in Aachen GEFA FLIGHT GmbH has been the mid-seventies with the development and the use of lighter -than-air vehicles and since 1980, especially with the development of the hot -air flight systems, which since then on various projects in over twenty countries to were used scientific and commercial purposes. Highlights of the recent technical development in 1996 co-developed with Thunder & Colt two-seater airship design, as well as a powerful four-seat hot -air airship, which according to the known rigorous and internationally accepted criteria by the German Luftfahrt-Bundesamt ( LBA) has been approved as a pattern in late 1999. A total of 25 such aircraft has made ​​up to the beginning of 2002, GEFA - FLIGHT.

In addition to aerodynamic research in the wind tunnel and the scientific investigation purely aerostatic questions by measurement flights with temperature sensors from on board and their computer- aided evaluation shell materials have been studied and developed suture techniques. Another focus of development was the attempt to improve the overall maneuverability means of a pneumatic rudder control, so as to reduce the physical workload of the pilot and his crew. Specifically, but especially the specifications of the technology project Nordrhein Westfalen had to meet the newly designed airship:

The specifications of the NRW technology project hot -air airship (1994-1999) were:

  • Type certification by the Federal Aviation Authority
  • Capacity for the transportation of four persons
  • Upgrading and use flight to 12 knots surface wind
  • Increase in flight speed to over 20 knots
  • Improve the overall maneuverability
  • Reduction and simplification of the controls (among ergonomic aspects )
  • Increase in flight hours on more than two hours
  • Team including pilot no larger than four people
  • Only a towing vehicle with trailer for transport of crew and aircraft necessary
  • Massive increase in the lifetime of the shell materials to 400 to 500 hours.

The road to success:

  • Scientific studies on aerodynamic and thermodynamic parameters of hot -air airship covers, inter alia, in the wind tunnel, by computer simulations and by determination of data by measuring flights
  • Studies on the positional stability and increase the maneuverability of hot -air airships in the wind tunnel
  • Case studies of different materials, the material behavior under flight conditions, and studies on the aging process of the shell material and the seams.
  • Optimization of sewing and stitching techniques from the point of higher security and improved life
  • Weight optimization of the overall system envelope and gondola by material analyzes
  • Flight test program for the purpose of determining various parameters concerning the placement stability and temperature distribution
  • Reflux and implementation of findings into series production
  • Development of internationally applicable building codes with the Federal Aviation
  • Setting up of a flight test program for type certification
  • Creation of a training concept for pilots with the Federal Minister for Transport
  • Establishing criteria for licensed inspector with the Federal Aviation
  • Certification of the GEFA FLIGHT according to JAR 21 as a development, production and maintenance operation by the Federal Aviation Authority

Areas of application

Hot -air airships serve a niche market. Wider distribution is in addition to the relative obscurity of the present possibilities, especially the still low technical capacity of these aircraft in ways that negatively reflected in the great weather sensitivity on the economy.

Aerial Advertising

The majority of the hot -air airships for use in the classical field of application, the air advertising. The general conditions of use are similar to those of hot air balloons. Because of the motor drive an airship However, unlike the balloon remain longer than a pre-selected location. Hot -air airships react like hot air balloons sensitive to thermal and are therefore preferably used with high sun positions ( April to September) in the first hours after sunrise and the last hour before sunset, because then the air due to weak or lack of thermals in the months is at its quietest.

With a flight time profile is suitable for the following usage of Aerial Advertising: The visit of major events of all kinds, which persist into the evening hours, such as open air concerts, festivals and sporting events. In addition, operations in the vicinity of motorways, motorway junctions and conurbations in the early morning and evening " rush hour ". In winter, the visiting audience strong and heavily publicized winter sporting events with flights along slopes or hills completes the scenario. In the shown here uses the hot -air airship is significantly superior to the hot air balloon from the advertising value here, because its route largely predictable and it's not like the uncontrollable balloon is at the mercy of the skies.

Hot air airships are often used as a camera platform of broadcasters and photojournalists. Instead of a fee for air time airtime is often agreed with the fading of the airship by a second camera on the ground. An "intelligent" version of " product placement ", as it is of course also be implemented with the gas airship.

Another not to be underestimated advantage of the hot-air airship over the gas-air ship is the fact that there is a start and can see the landing site in the immediate vicinity of the respective to visit event for almost all flight operations. So the audience active participants in the events around the airship are around, which in turn increases its advertising value.

Air Sports

Hot air airships are similar in many respects to the classic hot air balloon. The real difference from the hot air balloon is in the drive, which gives the hot -air airship its maneuverability. However, this maneuver is co-influences of the respective weather conditions. It was obvious to use these new aircraft also competitions and record purposes. However, it took about 15 years until it came in 1988 to conduct the first official World Championships in Luxembourg.

Hot air airship competitions consist of distance and triangle trips across country, slalom courses, demonstration of the general maneuverability, precision tasks with centimeter accurate dropping of markers and pylon race with " flying start ". The Sophisticated in these competitions is always the mixture of the individual identified by an international jury tasks for each task of the day, the pilots will be both psychologically and physically stretched to the limit.

Six World Championships have been held until 2004 in Europe. There were also several European Championships and some airship festivals and unofficial competitions. The first non-European World Cup was held in Canada in September 1998.

A German airship race took place on August 20, 2005 in Bad Homburg on the occasion of the 95th anniversary of the first German airship parade. It was attended by seven hot -air airships. First was Karl -Heinz Krug, second place went to Tanja Witte, was third Helmut Seitz.

The air sports and all kinds of championships and meetings and contribute greatly contributed to the development of hot -air airships. The same also applies to the substantially increased skills of the pilots.

Environmental Monitoring

A constantly growing market that can be operated with the hot -air airship, consists in environmental protection and environmental monitoring.

Since time immemorial, the use of balloons and airships for Erderforschung and environmental monitoring is promoted and carried out. In the twenties and thirties of the 20th century there were some flight expeditions to the Earth exploration. 1926 and 1928 the polar journeys of Amundsen and Nobile with the airships " Norge " and " Italia ", as well as 1931, the multi-day Arctic research cruise of the airship LZ 127 "Graf Zeppelin", headed by Dr. Hugo Eckener.

The advantages of airships and in particular hot -air airships against " heavier than air" flight systems for monitoring tasks are not limited to: to any length to hover over one spot and perform stopovers on non- scripted terrain, possibly with the collection of specimens of all kinds

In conjunction with the " tree raft " made ​​a French airship team important work to document the tropical flora. A " tree raft " is a construction of pontoons and networks which is deducted from the airship on the canopy of the rainforest. There, a research team collect plant samples that are analyzed for their medical usefulness. To larger areas can explore the airship with a pontoon triangle - a miniature form of tree raft - which is mounted under the airship, also collect samples. Since 1986, there have been several expeditions that took place in Cameroon, French Guiana and Brazil.

Photographic documentation, for example, the two castles of Neuschwanstein, of river landscapes in research projects of the World Wide Fund for Nature (WWF) in Germany and Austria and similar projects of the Union for Nature Conservation Germany with sometimes quite elaborate documentation of floodplains and riparian forests occupy a very impressive way, the suitability of hot air airships for environmental monitoring and short-range measurement. The hot -air airship often offers the best and often the only way of scientific studies carried out from the air, which are either very time-consuming, or even in some cases impossible from the ground. The use of " Heavier than aircraft" in this case is ruled out also because surface planes fly too fast and interfere with their helicopter rotor downwash just the sensitive areas, or even destroy that need to watch it.

A use of a special kind found in March 1994 in the far north of Norway, in Vadsø, the landing station of the polar expeditions of Amundsen and Nobile twenties of the last century instead. There, at the northernmost tip of Europe, far above the Arctic Circle in the Barents Sea remembered the "Eagle airship " as part of "Operation ARCTIC SKY '94 " with its mooring mast at the historic flights to former airship expeditions in the Arctic. The transport of a special international mail on board the " eagles airship " delivered by the sale of these letters donations in five-digit level for the Pestalozzi Children's Village at Lake Constance.

Another big strong commitment led an airship team in February 1998 to Tanzania in the Serengeti. They operated there in the footsteps of father and son Grzimek, who there with a single-engined Dornier 27 observes and analyzes the end of the fifties, the migration of large herds of animals. The "Eagle's airship" was used in 1998 once more as a camera platform for a film crew of the ARD and ARTE, to watch as the Grzimeks in the fifties, the migration of the great herds from the air. " Serengeti shall not die " was the expedition in analogy to 40 years earlier twisted, world famous and award-winning an Oscar movie Grzimeks. Also in this project a special post was promoted, also with donations in five-digit level. The film about this expedition was broadcast on various German and international TV channels over twenty times.

Technology

Historically, there are two types.

Natural overpressure

Firstly, there is the auskommende without artificial pressure type. Its shape he should receive only by the static pressure of the hot air in the envelope and a wind shield, the wind pressed into the shell. This concept is quite simple in manufacture and in use because it is very closely inspired in all components of the known hot air balloon. The burner system is located below the fill opening in an open gondola, which often resembles a balloon basket. Due to the small overpressure in the shell, the performance of these aircraft, however, is very limited. Operations can be performed only with ( almost) no wind gusts and only in free air.

Artificially generated overpressure

In order to increase the overall performance, the English company Thunder & Colt, a hot -air airship with artificial pressure developed from the late seventies. The overpressure was initially achieved in addition by a fan mounted downstream of the burner, and at a later time by the drive propeller. The burner unit is located at this types inside the now fully enclosed envelope.

However, the building types in both borrowed from the hot air balloon envelope material was also among the first overpressure types do not really high pressures to cover, or the life of the cases was usually less than 100 flight hours. This changed only with the use of high-tenacity nylon fabrics with silicone coating. The overpressure of up to 15 Pa, gas airships use compared a pressure of about 500 Pa.

Drive and control

As drive two-stroke spark ignition engines are used. Depending on the type of aircraft they have a power of about 20 - 50 kW. The usual fuel level is about 25 liters. For the gas burner for heating the air around 60 kg propane gas be carried.

Is controlled by a rudder, the level control is realized manually as in hot air balloon over the frequency and duration of operation of the most einflammigen burner system. Height and vertical stabilizers, as the shell, also purely pneumatic structures and located at the rear. The necessary for the stability of the tail pressure usually develops over a portion of the propeller air stream which is fed by an air scoop behind the propeller drive the control surfaces and where it leads to a positive pressure. The tail surfaces have no fixed components.

Hot -air airships have a takeoff weight of up to 900 kg.

Gondola

The gondola is usually made of a stainless steel tube frame and aluminum and plastic panels. It has room for two or four people. The seat assembly is carried out depending on the model side by side or in tandem configuration.

Comparison with gas airships

The development, manufacture and operation of gas airships is very cost- intensive, which in many areas of aviation precludes their use as before. Conventional gas airships are labor intensive in operation and cause even when temporary not in use, considerable costs, for example for the accommodation and care in a hangar. Gas airships can be operated only profitable when they come to a high number of flight hours over the year.

In all these points the hot -air airships have decisive advantages. When not in use they can be packaged, for example, on a transport trailer and so cause any significant additional cost. The gas - air ship reaches its respective location only with considerable expenditure on logistics ( ground crew, mooring mast, planning costs, etc.) and exclusively by air. The hot -air airship is, however, transported inexpensively in the trailer on the road. Gas-air ships of comparable size, such as hot -air airships have also today still mostly Teams 8-10 employees. Larger gas airships older design even require up to 20 people.

The ground crew of a hot-air airship, however, comes from three to four people, as these aircraft will be used only in favorable weather and for a few hours and re-packaged after successful use.

Apart from their lower efficiency hot air airships are more versatile than gas airships. Interestingly, this situation is particularly important when planning missions in distant countries where the gas airship either do not, or can but it is used only with immense transfer effort.

A significant disadvantage of the hot-air airship over the gas airship is the physically induced significantly greater volume necessary to arrive at comparable payloads. Helium has over heated air at the temperatures commonly used today by max. 127 ° C to about three to three and a half times the lift. This fact, by using much lighter shell fabrics are somewhat balanced and can be resized by the massive development of hot -air airships ( tear firmer materials and their higher temperature resistance ) even further. A significant difference is, however, purely physical reasons remain always exist.

Also hot -air airships will never reach the weather resistance of the gas-air ships, as the large hot -air airship cases not upgrade at higher wind speeds and turbulence ( bloat and fueling ) leave. Your operating limit is estimated at 12 to 15 knots maximum surface wind, which, if at all, only with considerable technological effort, a larger team and related major financial effort could overcome. This, however, the real advantage of the hot-air airship is to be compared with the gas airship, simple and inexpensive, diminished.

Some characteristic parameters for hot air airships are:

  • Cost-effective in the development and manufacturing, as technologically (still) quite easily
  • Inexpensive to operate, especially during brief, daily wise use
  • Small payload allows for only a short flight times; Flight operations have therefore usually local to regional character
  • Passenger Transportation in previous construction (usually only 1 passenger ) economically ( provisionally still) insignificant.

Training and pilot license

It is necessary to acquire the license to fly hot -air airships at least 6 hours of flight time and travel in Germany. Prerequisite for the conversion to hot air airships is the presence of a hot air balloon pilot license with sufficient flight experience.

Not only the pilot training needs, and the ground crew. The training includes these questions also with a. Is recommended that each pilot to bring his own team for training. Also contents of the training are also the themes maintenance and care, but also fundamental questions regarding the repair of the entire system.

Outlook and trends

Currently (as of 1 January 2008) there are three officially licensed companies that produce hot -air airships, the English suppliers Cameron Balloons / Thunder & Colt, Lindstrand Balloons and the German GEFA FLIGHT world. It is the small niche market, which is still relative weather limitations, the necessary and high specialized knowledge, but also the relative obscurity of the flight system hot -air airship, which is a distribution on a larger scale in the way. In addition, it must be considered that the operation of hot -air airships requires some financial outlay.

Whether it will also give more types in the future, in addition to those described herein, four-seater hot -air airships, depends on the development of the market for the currently available types.

Further development impetus for example on improving the maneuverability, along with the reduction of thermal sensitivity. The greatest potential lies in the development of envelope materials that are lighter and stronger, and allow higher temperatures for increased buoyancy and have a longer life. An increase in the internal pressure can be higher drive speeds than with the materials currently being used.

In GEFA FLIGHT and Festo, a manufacturer of pneumatic components, there are common considerations introduce a considerable degree of pneumatic control elements, both to increase the maneuverability, but also the ease of operation for the pilot. Several manufacturers are working on a so-called " pneumatic muscle " that could be used at several points.

The improvement of the hot-air vessels increases on one hand the efficiency, on the other hand reduces the space within the scope with respect to the gas-air vessel. They, or at least for the foreseeable future, but do not occur in real competition with each other but complement each other due to their different technology and application profiles.

The development potential of the hot-air airship be rated higher than that of the gas-air vessel, which among others is its 150-year history of development for military purposes on a much higher stage of development and is therefore developed only in smaller increments. The physically-dependent difference of the different densities of heated air and helium as carrier gas will remain.

Manufacturers and models

(Selection, according to the manufacturer)

  • Augur Aerostatic Systems, Inc. ( RosAeroSystems - Russia) AV -1R ( two seats in collaboration with the Czech company Kubicek, sro )
  • Au -29 ( single seat )
  • Model A- 3 and A- 5
  • AS80GD
  • AS105GD
  • AS105MKII
  • AS120MKII
  • AS 105 GD ( two or four seats )
  • AS 105 GD / 6 ( sechssitzig )
  • HS110
Type certificate Computersimulation Controlled-access highway Rush hour (disambiguation) Wintersport Slalom skiing Roald Amundsen Umberto Nobile Norge (airship) Airship Italia LZ 127 Graf Zeppelin Rudder#Aircraft rudders Tandem (disambiguation)
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