Zeppelin NT

Zeppelin NT ("Neue Technologie", German for new technology) is an airship type that has been manufactured since the 1990s by the German company Zeppelin Luftschifftechnik GmbH (ZLT) in Friedrichshafen. It is classified as a semi-rigid airship.

This company can be considered the successor of the companies founded by Ferdinand von Zeppelin which constructed and operated the very successful Zeppelin airships in the first third of the 20th century. There are, however, a number of notable differences between the Zeppelin NT and the dirigibles of those days, as well as between the Zeppelin NT and usual non-rigid airships known as blimps.

Technology

The Zeppelin NT airships constructed so far are 75 m long, with a volume of 8,225 m³. They are thus considerably smaller than the old Zeppelins. Furthermore, they are inflated exclusively with the non-flammable noble gas helium.

In standard operations with a maximum payload, the gas cells do not create enough buoyancy to make the whole ship "lighter-than-air." The negative buoyancy is overcome with engine power. The buoyancy can change when traveling with reduced payload and partially emptied fuel tanks, but usually the Zeppelin NT flies with a net downward force of about 3,000 N (306 kg).

Some have erroneously described the design as a hybrid airship. However that term is most often used only for aircraft that use aerodynamic forces to carry at least 40% of the total aircraft weight. The aircraft is most accurately characterized as an airship that uses vectored thrust to compensate for its static heaviness.

The Zeppelin NT is a semi-rigid airship. It is unlike both the original Zeppelins that had a rigid skeleton and non-rigid blimps. It has an internal triangular truss made of graphite-reinforced plastic and three longitudinal girders made of aluminium which connect the triangular elements along the length of the frame. This frame holds the engines, control car and the steering fins. Additionally, this structure is tightened with aramid cords. It weighs only about 1,000 kg (2,200 pounds).

The company's marketing materials repeatedly, and incorrectly, refer to the aircraft as a rigid airship. This usage has led to some confusion in media reports.

Hull

Inside the hull of the historical Zeppelins the gas cells were separate entities. However the hull of the Zeppelin NT serves both as the hull and as the gas cell. It is made of a three-layered laminate: one gas-tight layer of Tedlar (PVF), one polyester fabric layer to provide stability and one polyurethane layer suitable for thermic welding that serves to connect the separate laminate panels.

To preserve its outer form, a slight overpressure of about 5 millibar is maintained within the hull. As in blimps, this pressure is kept constant by using ballonets. The ballonets have a total volume of 2,000 m³.

Propulsion and steering

Three propeller engines of the type Textron Lycoming IO-360 with a power of 147 kW (200 metric hp) each provide the Zeppelin NT with excellent maneuverability. Two lateral engines, equipped with tilting propellers and usually aligned horizontally, can be turned 90° upward or 30° downward. The aft engine powers a pushing propeller that can be turned 90° downward, as well as a steering propeller directed to the side and working similarly to the lateral-thrust units of some ships.

Instead of four rudder and elevator fins, the Zeppelin NT uses only three, which saves weight. As a side effect, the loss of one fin can be compensated with the remaining two.

The controls are implemented by fly-by-wire technology, with the pilot using a joystick to steer in three dimensions.

Flying capabilities

The design currently has a range of some 900 km (500 nautical miles) and reaches top speeds of 125 km/h (70 nautical mph or 78 mph). The standard cruising speed of 70 km/h for tourist flights can be attained using the rear propeller only. Standard operational altitude is 300 m (1000 ft), but up to 2,600 m (8,500 ft) is possible. Their maximum permitted takeoff weight is 10,690 kg, with a payload of 1,900 kg.

The Zeppelin NT is able to take-off and land vertically. Only three helpers are required on the ground.

Capacity

The Zeppelin NT has a passenger capacity of 12, plus 2 crew, or the capability to lift 1,900 kg of payload.

Range of application

Since August 15, 2001 the Deutsche Zeppelin-Reederei (German for German Zeppelin shipping company) has successfully offered joyrides with Zeppelin NT airships. The hull surfaces are marketed as advertising space. The DZR was founded as a subsidiary of the ZLG in January 2001.

The craft are also used as observation platforms for photographers and television commentators covering major events.

Due to their capability for long low-vibration flight (up to 24 hours), the ZLG also considers the airships well-suited to research missions for environmental observations, troposphere research or prospecting natural resources.

Project history

The modern development and construction was financed from an endowment, initially funded with money left over from the earlier Zeppelin company, that had been under the trusteeship of the Mayor of Friedrichshafen. A stipulation on the endowment limited use of its funds to the field of airships. Over the many years, the investment value of the endowment grew to a point where the time seemed right to use it for the design, development, and construction of a new Zeppelin.

The initial design study was prepared in 1989. The ZLT was founded as a spin-off of the Zeppelin company in September 1993. It began to construct a prototype in 1995. The prototype first took to the air in September 1997.

On July 2, 2000, the centennial of the first Zeppelin flight, the prototype SN 01 was christened D-LZFN Friedrichshafen. Subsequently, it traveled some 3,600 km in test flights.

In 2001 the company began manufacturing the Zeppelin NT in series and began to exploit the airships commercially. The second ship SN 02 was christened D-LZZR Bodensee on August 10, 2001 and started to give joyrides five days later. By the end of that year, it had already transported 3222 passengers, a figure that rose to about 30,000 by November 2003.

During the Oktoberfest of 2002 a Zeppelin NT was used for radio experiments in connection with the European Galileo positioning system project for the German Aerospace Center and the ESA.

The third Zeppelin NT SN 03 was designated D-LZZF and first flew in February 2003.

The Friedrichshafen is intended to be used for training pilots, for special flights and for presentations. All further ships will be used commercially or sold. As a tribute to the days of Zeppelin mail, a number of mail-carrying flights are planned.

On March 2, 2004 the ZLT sold a Zeppelin NT for the first time; SN 02 was acquired by the Japanese Nippon Airship Corporation and was transferred in June 2004, and was to follow the historical route of the 1929 World Tour of the famous dirigible LZ127 "Graf Zeppelin". After problems with Russian authorities a special ship for huge parts from the Netherlands was chartered and the Zeppelin was shipped from Italy to Japan by sea. The company intends to use the airship mainly for sightseeing and advertising.

Steve Fossett and Paul Stroehle set the current speed record for airships over a distance of one kilometer on Wednesday, October 27, 2004 in Friedrichshafen, Germany with a Zeppelin NT. The new world record was set to 111.8 km/h (69.5 mph or 60.4 knots), an improvement of 19 km/h.

Starting in late 2005 the prototype Zeppelin NT, D-LZFN Friedrichshafen, was based in Jwaneng, a diamond mining town in southern Botswana, where it conducted an airborne geophysical survey on behalf of De Beers Prospecting Botswana. The airship was moved from Amsterdam to Cape Town by ship and then flown to Gaborone where a Lockheed Martin full tensor gravity gradiometer was installed. This instrument, owned and operated by Bell Geospace, measures changes in the Earth's gravity field associated with geological density variations. The technology is based on accelerometers and the data quality is sensitive to the turbulence and motion usually associated with fixed wing aircraft installatons. The airship, flying slowly at night in relatively cool calm air, provides a very stable and vibrationaly quiet platform. The resulting data is capable of revealing the rather faint gravity signals associated with Kimberlite pipes buried under the Kalahari sands. This survey came to an end on 20 September 2007, when D-LZFN was irreparably damaged by a whirlwind while moored at its mast.

In January 2006 the Zeppelin Luftschifftechnik GmbH announced building a fourth Zeppelin NT07 with an expected completion date of sometime in 2008. NT07 #4 was optioned by California based Airship Ventures in Spring 2007. .

External links

• Zeppelin Luftschifftechnik GmbH -- manufacturers' homepage
• zeppelintours.com -- trips to Friedrichshafen and Zeppelin NT airship flights
• Deutsche Zeppelin Reederei -- booking joyrides with Zeppelin NT airships
• Airship Ventures Inc. -- US company bringing a Zeppelin NT to the USA.