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| | Zeppelin is a rigid type of airships, built by Count Zeppelin & German firm “Luftschiffbau Zeppelin GmbH”. Airships are named after their inventor & founder Ferdinand Zeppelin. 119 Zeppelins were constructed during 1899-1938 and were designated LZ as per the dockyard, for example, LZ 127. Zeppelins were massive & modernized representatives of rigid-type dirigibles. Zeppelins, supplied to army & navy, were, as a rule, named accordingly in their respective defense departments; for example, dirigible LZ 104 (according to shipyard) in navy is renamed as L 59. Sometimes, word Zeppelin is not precisely used as synonym of rigid dirigible.
Rigid airship – type of airship, basic peculiarity of which is distribution of carrier gas along separate closed compartments, arranged inside the metallic (very rarely – wooden) skeleton, covered with cloth. Skeleton bears entire loads & releases excess pressure of carrier gas if required by means of air bags (ballonets) (unlike soft & semi rigid airships). Air ships of this type were more massive dirigibles: some of them had length of almost ¼ km & had maximum diameter of more than 40m. Around 150 rigid air ships were constructed from end of XIXth century till the end of 1930s. Small rigid air ship D. Schwarz with metallic covering was constructed in 1897. Sometimes every rigid airship is incorrectly called Zeppelin.
Design:
Metal skeleton of rigid airships was manufactured, as a rule, from duralumin & consisted of cross-sectional & longitudinal girders. Cross-section girders looked like polygon (for example, 28-angle bars in “Count Zeppelin”, 36 angle bars in “Hindenburg”) and were called frames. Frames were arranged at a distance of 3.8 – 22.5m (predominantly 10—15m) from each other and usually from 1 to 3 auxiliary frames were positioned between these frames, called main frames. Main frames of overwhelming majority of rigid airships (with an exception, for example, British R.101 & American “Akron”) were braced with ropes, located in plane of frames. Longitudinal girders, passing through the length of entire airship from nose to stern, were called stringers. Often, even they were divided into main & intermediate stringers & were connected with frames at top. Quantity of stringers usually decreased at nose part & at stern and stringers ended with dome-shaped nose & cone-shaped stern. Thus, frames and stringers formed rectangular panels, braced crisscross with ropes – diagonal bracing, on the surface of skeleton. Apart from diagonal bracing, even auxiliary bracing was made, which looked like network and passing along internal surface of skeleton and string network, which served for bearing gas pressure from filled gas bags. Corridor (fin), serving for communicating with gondolas & for arranging various consignments and also containers with fuel, oil & water, passes along the entire length of airship in bottom portion of skeleton. Some later airships had 2 – 3 longitudinal corridors.
Carrier gas (hydrogen, helium) was filled in gas bags, in most cases, are made from balloon fabric: three-four layers balloon fabric (material, manufactured from blind gut of horned cattle) are glued on fabric lining & impregnated entire thing by varnish. Number of gas bags fluctuated from 12 to 20. As a rough approximation, they had cylindrical form & occupied envelope compartments between two adjacent main frames. Each gas bag was equipped with automatic safety gas valve; apart from that, some gasbags had maneuvering gas valves.
External cover jacketed entire envelope from outside & served for lending aerodynamic shape to air ship & for protecting the gas bags from hostile atmospheric effects. Cover consisted, as a rule, of cotton cloth coated with cellon; aluminum powder was added to cellon for much later Zeppelins, which lent silver shade to the airship.
Empennage & operating controls were located, with an exception of earlier models, on the stern of rigid airships. Empennage looked like cross and consisted of 2 vertical fins, ending with yaw rudders & 2 horizontal stabilizers, terminating with elevators.
As a rule, several gondolas were fitted outside the airship for controlling the airship, for arranging the engines & passengers. Passenger compartments were located inside the skeleton in later rigid airships. Upto 6 motor gondolas were fitted on airship & number of engines touched upto 8. Engines were fitted inside the body on American “Akron” & “Macon”.
Advantages & short-comings:
In comparison with airships of other systems (soft, semi-rigid), rigid airships had number of advantages:
* Rigid skeleton allowed construction of very large-sized airships. While volumes of soft and semi-rigid airships did not exceed 30000 - 40 000 m³, volume of rigid air ships reached 200 000m³. Profitability of airship increased in direct proportion with increase in volume. Owing to his, rigid airships were considered to be more suitable for work in airlines across the globe- for transportation of sizeable cargoes for farther distances;
* Rigid airships allowed comfortable location of passenger compartments (by means of setting up 2-3 decks in skeleton) & ensured low noise & vibration levels for passengers (due to fitting of engines away from passenger compartments);
* Rigid skeleton provided complete shape stability during flight, which reduced the aerodynamic resistance; thanks to low aerodynamic resistance, Zeppelins were considered to be high-speed airships at that time;
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