Hybrid airship
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Hybrid airship has two meanings. First, it can be an airship combining elements of different types of airships. It can also be used to describe an aircraft that combines characteristics of heavier-than-air, (HTA), (fixed-wing aircraft or helicopter) and lighter than air, (LTA), technology. Examples include helicopter/airship hybrids intended for heavy lift applications and dynamic lift airships intended for long-range cruising. This article focuses on hybrids that combine heavier-than-air and lighter-than-air technologies.
Under the trademark SkyCat(TM), hybrid air technology vehicles, have been proposed that derive more than half their lift by helium buoyancy and the balance of their lift by aerodynamic shaping and such vehicles are not payload specific
Most modern airships, for instance the Zeppelin NT, use some combination of vectored thrust and buoyancy. However, for these designs, almost all of the load is carried via buoyancy and vectored thrust is used primarily for maneuvering. To date, there is no formal distinction between a hybrid airships and airships with vectored thrust. However, most people in the field usually define a hybrid airship as one that carries at least 40% of the weight of the loaded ship by aerodynamic means.
Using the above definition, no practical human-carrying hybrid airships have been built to date. However, many designs have been proposed and some prototypes built.
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[edit] Concept
Ground handling of airships has historically presented great difficulty. When a purely LTA ship comes in for a landing, it is nearly neutrally buoyant and is very susceptible to wind buffeting. In even a slight breeze, a truck or many ground crew members are required to secure the ship to a mooring mast.
With hybrid designs, as much as 40% of its total lift is created by aerodynamics. So, when on the ground, it is much heavier than a purely static lift design and can presumably taxi around like an airplane. The advent of hover cushion landing systems (replacing wheels), and possessing a suck down mode has solved the ground handling problems of airships, resulting in remote operations is areas of the world previously inaccessible to airships and conventional aircraft. The aerodynamic approach is very similar to that of a conventional lifting body aircraft. The hybrid aircraft technology has a wide range of flight performance behaviors ranging from heavier than air to near buoyant characterizations. This uncommon dynamic flight range when coupled with the Air Cushion Landing System has reinvigorated even the LTA community and those seeking ultra heavy and affordable airlift transportation options.
The combination of aerodynamic and aerostatic lift is a modern day vehicular technology amalgamation called SkyCat(TM) in an attempt to create a craft that is a "best of both worlds" combination with the high speed of aerodynamic craft and the lifting capacity of aerostatic craft. However, despite the success of Lockheed Martin in this design and developmental program and that of the Hybrid Aircraft Corporation in supporting hybrid designs, the hybrid aircraft is not without their detractors. Critics of the hybrid approach have incorrectly labeled it as being the "worst of both worlds" declaring that such craft require a runway for take-off and landing, are difficult to control and protect on the ground, and have relatively poor aerodynamic performance. Lockheed Martins P-791 manned flight test of the SkyCat(TM) technology in CY-2006 has since conclusively demonstrated that critics assertions are rubbish.
The type of hybrid aircraft technology described above, and sometimes referred to as hybrid aircraft, have been "coined" as "SkyCat" to reduce ambiguity in addressing the vehicular design which derives more than half of its lift from helium buoyancy and the balance by aerodynamic shaping. Such vehicle technology when referred to as "SkyCat" are not payload specific and it would be inappropriate and unlawful (because the descriptive technology is trademarked)to declare SkyCat as a product name. SkyCat is a registered trademark name of the Hybrid Aircraft Corporation, Albuquerque, New Mexico. USPTO Serial Number 78562650. The Hybrid Aircraft Corporations air cargo transport product name is SkyFreighter (TM). lfoltzer
[edit] History
No hybrid aircraft design has ever been developed past the initial experimental stages. And, in spite of the fact that many such designs have been proposed over the years, very few proposed designs have flown.
In 1905, Alberto Santos-Dumont, made what is likely the first attempt at a hybrid aircraft. His Number 14 combined an airship envelope with an airplane frame. At that time, Santos-Dumont was the world's most accomplished aviator. All of his previous flights had been made in purely aerostatically lifted airships. The Number 14 proved unworkable. Later, Santos-Dumont would remove the envelope and successfully use the recristened 14-bis (meaning 14-again) to make the first public flight of any heavier-than-air aircraft in the world.
One example of hybrid aircraft design that did take flight was the Aereon 26. The development of this aircraft was documented in the book "The Deltoid Pumpkinseed" by John McPhee.
The SkyCat vehicular technology is a hybrid aircraft amalgamation; a scale version at 12 metres "SkyKitten", flew in 2000. ATG the UK company who fashioned the small unmanned air vehicle borrowed from Lockheed Martins Aerocraft designs, is now defunct.
[edit] Current and proposed designs
The WALRUS DARPA program has been incorrectly referred to as an airship or hybrid development program. The WALRUS program in fact was a technology development initiative focused on ultra heavy air lift technology explorations.
The Aeroscraft, a design proposed by Worldwide Aeros Corp is also a hybrid airship that uses a lifting body shape, vectored thrust, as well as buoyancy control.
[edit] Treatment in fiction
H.G. Wells' novel Tono-Bungay features the protagonists working on hybrid airship designs with arguable lack of success.
