onsdag 23. mars 2016

Airship raising - AW&ST

A Potted History Of Airships

RSS
From the dawn of aviation, through to the modern day, the airship has undergone sporadic revivals. A pattern emerges that the airship’s sustainability comes down to economics. 
Airships have been developed since the 1800s but Aviation Week began publishing 100 years ago, so it is worth noting that a revival was taking place as far back as November 1916 when we reported that the U.S. was to start work on a lighter-than-air-vehicle, another name known for airships.
A journalist predicted in the February 1, 1917 issue of Aviation Week, that great progress would be made in developments of lighter-than-air craft in the U.S., and similar predictions for Europe were foretold.
All types of lighter-than-air aircraft would be designed and built by one company, the Connecticut Aircraft Co. Its qualification? It recently received an order from the Signal Corp for an observation balloon.
It had a capacity of 30,000 cubic feet of hydrogen. The main gas bag was built of double textured rubberized cotton, cemented and sewn together.
In 1925, the Goodyear Pilgrim performed its first flight at Akron, Ohio. It was 110 ft long, 45 ft. high, powered by 80 hp Lawrance radial engine. It could transport two passengers plus a pilot and motor mechanic.
It was known then as the world’s smallest airship, and first commercial lighter than air craft inflated with helium. It was intended for pleasure cruising, but a demonstration ship would be built for certain tests and experimental work.
PW Litchfield, vice president of Goodyear said the future of these ships might bring mooring masts at country clubs, and on private estates and even airship regattas in the same way the motor boat and yachting clubs now have similar events.
In 1927, Goodyear printed a booklet about the evolution of airships. The lighter than air vehicles take many forms, airships, balloon designs, non-rigid airships, semi-rigid airships, rigid airships, commercial and military uses of airships.
The British State airship R101 was completed in 1929. It took four years. The first 18 months were dedicated to “pure research work in wind tunnels” and the last two years on actual construction.
The writer described its construction: "The main longitudinal girders are triangular in section with booms, of high tensile steel strip drawn into tube form with duralumin webs and forged duralumin end fittings all attached to pin joints… which helps to improve the accuracy of the stress analysis."
At the time of this report [the later doomed] R101 had not yet made first flight, but the writer said that when it does take to the air it will be the first airship which does not rely on gasoline.
In May 1936 the Hindenburg flew on its first scheduled commercial flight across the north Atlantic. A sketch within the article is captioned: “A glimpse into the future. These sketches (showing passengers enjoying the view from the airship) are made from a study by Goodyear-Zeppelin Corp. and its accommodations compare favorably with those found on luxury steamships of today.”
The writer said: “I believe the airship is destined to be successful in the transoceanic field because its inherent qualifications permit it to carry large payloads economically over large distances.”
Sadly, however, The Hindenburg burst into flames in 1937, bringing into question the future of airships.
In July 1959 the first of four Goodyear airborne early warning airships was delivered. "The ZPG-3Ws are the largest non-rigid airships ever built, at 1.5 million cu. ft. helium volume, and are being produced by Goodyear under a $48 million Navy contract. It has a large antennae carrying capability, has long endurance, easy station keeping over a fixed geographical position, and lower noise and vibration."
The airship power plants are two Wright R-1820-88 engines rated, 1525 hp. Maximum fitted with Curtiss Electric propellers.
In 1984 the US Navy wanted an airship capable of performing coast guard missions which would fly with turboprop engines in 1989.
From 1987 the US Navy funded the project. Then discontinued its support due to budget cuts. However, the Navy followed to program with much interest according to a Westinghouse official.
Airship Industries partnered with British firm Westinghouse to produce a design to meet the Navy’s needs. It would provide real-time data on the location, movement and identification of air surface and subsurface targets. The Sentinel 1000 had its first flight June 26, 1991.
In 2008, Aviation Week reported on airship manufacturer Worldwide Aeros ’ “new class of aircraft”, much like an airship with gas buoyancy, aerodynamic lift, and thrust vectoring for better performance and operability than traditional airships.”
The Aeroscraft ML866 is a 210 ft. long vehicle aimed at the business aviation market. It is a buoyancy-assisted aircraft with adjustable static heaviness. Its key technology is the dynamic buoyancy management system. “The control of static heaviness works by compressing storing, then decompressing helium within the envelope to adjust the vehicle’s buoyancy.Aeroscraft ML866 is a 210 ft. long vehicle aimed at the business aviation market. It is a buoyancy-assisted aircraft with adjustable static heaviness. Its key technology is the dynamic buoyancy management system. “The control of static heaviness works by compressing storing, then decompressing helium within the envelope to adjust the vehicle’s buoyancy.
“Static heaviness is the ratio of buoyancy to gravity; it is increased to land, and decreased for takeoff.”
The ML866 was five times that of a large business aircraft with a huge cabin area of 5,400 sq. ft. and would be able to carry 28 passengers.
In 2010 Aviation Week featured a new generation of airships capable of “persistent surveillance”.
“Airships are survivors”, having been around since the dawn of aviation, but questions whether “an unmanned airship can last beyond today’s war?” Northrop Grumman believes so, and that it has a role to play in border security and disaster relief as a communications and surveillance platform.”
“Airships are not for everything,” said a company executive, “but there are opportunities they are suited for. It comes down to economics.”
Northrop Grumman’s long endurance multi-intelligence vehicle (LEMV) would be able to provide surveillance for 21 days from 20,000 ft.
It would work with Hybrid Air Vehicles (HAV) – companies which preceded HAV developed the Skyship 500 and 600 and the Sentinel 1000, which never materialized.
The LEMV, “an aircraft the size of an A380 with rotating engines” flew for 90 mins. on its first flight on August 8, 2012, “a remarkable achievement to go from concept to first flight in 25 months.”
Hybrid Air Vehicles, a U.K. airship developer launched the "return-to-flight" program for its Airlander 10 vehicle back in 2015 and has now begun flight tests. The Bedfordshire-based company is rebuilding the 302-ft.-long HAV304/Airlander 10 after acquiring it from the U.S. Army following cancelation of the Northrop Grumman-led Long-Endurance Multi-intelligence Vehicle (LEMV) program. 
The craft is awaiting its Permit to Fly from the U.K. Civil Aviation Authority and the European Aviation Safety Agency. A first flight date has yet to be set.

Ingen kommentarer:

Legg inn en kommentar

Merk: Bare medlemmer av denne bloggen kan legge inn en kommentar.