Semi-rigid airship

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Internal structure of semi-rigid airship Semi rigid airship.jpg
Internal structure of semi-rigid airship

A semi-rigid airship is an airship which has a stiff keel or truss supporting the main envelope along its length. The keel may be partially flexible or articulated and may be located inside or outside the main envelope. The outer shape of the airship is maintained by gas pressure, as with the non-rigid "blimp". Semi-rigid dirigibles were built in significant quantity from the late 19th century but in the late 1930s they fell out of favour along with rigid airships. No more were constructed until the semi-rigid design was revived by the Zeppelin NT in 1997.

Contents

Semi-rigid construction is lighter-weight than the outer framework of a rigid airship, while it allows greater loading than a non-rigid type.

Principle

More or less integrally attached to the hull are the gondola, engines and sometimes the empennage (tail). The framework has the task of distributing the suspension loads of these attachments and the lifting gas loads evenly throughout the whole hull's surface and may also partially relieve stresses on the hull during manoeuvres. In early airships which relied on nets, fabric bands, or complicated systems of rope rigging to unite the lifting envelope with the other parts of the ship, semi-rigid construction was able to achieve improvements in weight, aerodynamic, and structural performance. The boundary between semi-rigid and non-rigid airships is vague. Especially with small types, it is unclear whether the structure is merely an extended gondola or a proper structural keel.

As in non-rigid airships, the hull's aerodynamic shape is maintained by an overpressure of the gas inside and light framework at the nose and tail. Changes in volume of the lifting gas are balanced using ballonets (air-filled bags). Ballonets also may serve to provide pitch control. For small types the lifting gas is sometimes held in the hull itself, while larger types tend to use separate gas cells, mitigating the consequences of a single gas cell failure and helping to reduce the amount of overpressure needed. [1]

History

Italian explorer Umberto Nobile crossed the North Pole in his semi-rigid airship Norge in 1926. Norge airship in flight 1926.jpg
Italian explorer Umberto Nobile crossed the North Pole in his semi-rigid airship Norge in 1926.

In the first decade of the twentieth century, semi-rigid airships were considered more suitable for military use because, unlike rigid airships, they could be deflated, stored and transported by land or by sea. [2] Non-rigid airships had a limited lifting capacity due to the strength limitations of the envelope and rigging materials then in use.

An early successful example is the Groß-Basenach design made by Major Hans Groß from the Luftschiffer-Bataillon Nr. 1 in Berlin, the experimental first ship flying in 1907. It had a rigid keel under the envelope. Four more military airships of this design were built, and often rebuilt, designated M I to M IV, up to 1914. [3]

The most advanced construction of semi-rigid airships between the two World Wars took place in Italy. There, the state-factory Stabilimento di Costruzioni Aeronautiche (SCA) constructed several. Umberto Nobile, later General and director, was its most well-known member, and he designed and flew several semi-rigid airships, including the Norge and Italia , for his overflights of the North Pole, and the W6 OSOAVIAKhIM , for the Soviet Union's airship program.

List of other semi-rigid airships

Pre-War and WWI

1920s and 1930s

Nobile's company designed or built the following airships:

Current developments

As of 2008, the only manned semi-rigid model of airship in active operation is the Zeppelin NT. It comprises a single gas cell kept at a slight over-pressure, ballonets to maintain constant volume, and a triangular keel structure internal to the cell. Three of these will be American-based airships.

CL160 "Cargolifter" was an unrealised design of the now liquidated German Cargolifter AG (1996–2003). [5] [ unreliable source? ]Cargolifter Joey was a small semi-rigid experimental airship produced to test the design [5]

See also

Related Research Articles

<span class="mw-page-title-main">Blimp</span> Non-rigid airship

A blimp, or non-rigid airship, is an airship (dirigible) without an internal structural framework or a keel. Unlike semi-rigid and rigid airships, blimps rely on the pressure of the lifting gas inside the envelope and the strength of the envelope itself to maintain their shape.

<span class="mw-page-title-main">Airship</span> Powered lighter-than-air aircraft

An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air.

<span class="mw-page-title-main">Aerostat</span> Lighter-than-air aircraft

An aerostat is a lighter-than-air aircraft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships. A balloon may be free-flying or tethered. The average density of the craft is lower than the density of atmospheric air, because its main component is one or more gasbags, a lightweight skin containing a lifting gas to provide buoyancy, to which other components such as a gondola containing equipment or people are attached. Especially with airships, the gasbags are often protected by an outer envelope.

<i>Norge</i> (airship) Italian polar-expedition airship

The Norge was a semi-rigid Italian-built airship that carried out the first verified trip of any kind to the North Pole, an overflight on 12 May 1926. It was also the first aircraft to fly over the polar ice cap between Europe and America. The expedition was the brainchild of polar explorer and expedition leader Roald Amundsen, the airship's designer and pilot Umberto Nobile and the wealthy American adventurer and explorer Lincoln Ellsworth who, along with the Aero Club of Norway, financed the trip, which was known as the Amundsen-Ellsworth 1926 Transpolar Flight.

<span class="mw-page-title-main">Rigid airship</span> Airship in which the envelope is supported by a framework

A rigid airship is a type of airship in which the envelope is supported by an internal framework rather than by being kept in shape by the pressure of the lifting gas within the envelope, as in blimps and semi-rigid airships. Rigid airships are often commonly called Zeppelins, though this technically refers only to airships built by the Luftschiffbau Zeppelin company.

<span class="mw-page-title-main">SSSR-V6 OSOAVIAKhIM</span> Soviet airship

SSSR-V6 OSOAVIAKhIM was a semi-rigid airship designed by Italian engineer and airship designer Umberto Nobile and constructed as a part of the Soviet airship program. The airship was named after the Soviet organisation OSOAVIAKhIM. V6 was the largest airship built in the Soviet Union and one of the most successful. In October 1937, it set a new world record for airship endurance of 130 hours 27 minutes under command of Ivan Pankow, beating the previous record by the German airship Graf Zeppelin.

<span class="mw-page-title-main">No. 9r</span> Type of aircraft

HMA No. 9r was a rigid airship designed and built by Vickers at Walney Island just off Barrow-in-Furness, Cumbria. It was ordered in 1913 but did not fly until 27 November 1916 when it became the first British rigid airship to do so. It was dismantled in June 1918 after being flown for around 165 hours, mainly for experimental purposes.

<span class="mw-page-title-main">Paul Haenlein</span>

Paul Haenlein was a German engineer and flight pioneer. He flew in a semi-rigid-frame dirigible. His family belonged to the Citoyens notables, those notabilities who led the economy, administration and culture of Mainz.

<i>Roma</i> (airship) US Army airship destroyed in 1922

Roma was an Italian-built semi-rigid airship, designated by its designer as the Model T-34. Purchased by the United States from the Italian government in 1921, Roma was operated by the United States Army Air Service from November 1921 to February 21, 1922, when it crashed in Norfolk, Virginia, killing 34 people aboard, with 9 survivors. As a result of this accident, Roma was the last hydrogen inflated airship flown by the US military; all subsequent airships were inflated with helium.

<span class="mw-page-title-main">Ballonet</span> Air-filled bags inside the envelope of an airship

A ballonet is an inflatable bag inside the outer envelope of an airship which, when inflated, reduces the volume available for the lifting gas, making it more dense. Because air is also denser than the lifting gas, inflating the ballonet reduces the overall lift, while deflating it increases lift. In this way, the ballonet can be used to adjust the lift as required.

<span class="mw-page-title-main">Parseval PL25</span> German WW1 airship

PL25 was a non-rigid military airship made in 1914/15 by the Luft-Fahrzeug-Gesellschaft in Bitterfeld and was the last single-gondola Parseval. At the same time it was one of the largest non-rigid airships before the second world war. Its maiden flight was on 25 February 1915. It had a slim teardrop-shaped hull.

Gross-Basenach or Groß-Basenach is the designation for a series of five so-called M-class German military semi-rigid airships constructed by balloonist Nikolaus Basenach and Major Hans Georg Friedrich Groß (1860–1924) of the Royal Prussian Airship Battalion Nr 2 between 1907 and 1914.

<i>Patrie</i> (airship) 1900s French airship

The Lebaudy Patrie was a semi-rigid airship built for the French army in Moisson, France, by sugar producers Lebaudy Frères. Designed by Henri Julliot, Lebaudy's chief engineer, the Patrie was completed in November 1906 and handed over to the French army the following month. The Patrie bears the distinction of being the first airship built specifically for military service.

<span class="mw-page-title-main">Soviet and Russian airships</span>

This article outlines some of the non-rigid and semi-rigid airships used in or built in Russia and the Soviet Union.

<i>La République</i> (airship) 1900s French airship

The Lebaudy République was a semi-rigid airship built for the French army in Moisson, France, by sugar manufacturers Lebaudy Frères. She was a sister ship of the Patrie, the main differences between the two being in the dimensions of the gasbag and the ballonet. Although she was operationally successful, the République crashed in 1909 due to a mechanical failure, killing all four crew members.

<span class="mw-page-title-main">Goodyear RS-1</span> Type of aircraft

The Goodyear RS-1 was the first semi-rigid airship built in the United States. The airship was designed by chief aeronautical engineer and inventor, Herman Theodore Kraft with the Goodyear Tire and Rubber Company for the United States Army Air Service in the late 1920s. Goodyear built only one airship of this type.

<span class="mw-page-title-main">Lebaudy Morning Post</span>

The Lebaudy Morning Post was a French semi-rigid airship built for the British Army in Moisson, France, by manufacturers Lebaudy Frères. The airship was commissioned by the newspaper The Morning Post, who created a fund to purchase the airship and present it to the British Army. The airship's envelope was damaged on the delivery flight and then it was destroyed on a subsequent trial flight after repair. At the time of construction it was the largest airship that had been built in France.

References

Notes

  1. U. Nobile "Semi-Rigid v. Rigid Airships" FLIGHT, 22 January 1922
  2. Flight 4 July 1909 Flight Magazine Global Archive: "The dirigible must be of the frameless or of the semi-rigid sort, because experience on the Continent has proven that for military service the rigid type, exampled more particularly by the Zeppelin school, cannot be collapsed and packed into small compass for the purposes of transport, which are among the War Office requirements."
  3. pilotundluftschiff.de. Halbstarre Luftschiffe vom Typ Groß Basenach last accessed 2008-07-05
  4. Scientific American, 31 December 1904:'The Lebaudy Airship, "Le Jaune" Ascending From the Meadows of Moisson,' France
  5. 1 2 CargoLifter CL160 P1 Super Heavy-Lift Cargo Airship, Germany - Aerospace Technology

Bibliography

  • Belokrys, Aleksei. Deviat'sot chasov neba. Neizvestnaia istotriia dirizhablia "SSSR-V6" [Nine Hundred Hours in the Sky. The Unknown History of the Airship "SSSR-V6"]. Moscow, Russia: Paulsen, 2017. ISBN   978-5-98797-174-1 (in Russian).