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1998 International ConferenceSummaries
of papers
Sommaires des conférences
Proceedings available from CASI
Compte-rendu disponible à l'IASC
Keynote Speaker / Conférencier d'Honneur
Mr. David R. Lavis
Band, Lavis and Associates, Inc.
USA
FORTY YEARS OF HOVERCRAFT DEVELOPMENT
The paper discusses the current world-wide state of development of hovercraft including Air Cushion Vehicles (ACV's) and Surface Effect Ships (SES) in their commercial and military applications. Included are accounts of developments of historical importance, descriptions of current designs and subsystems technologies. Technologies discussed in some detail include those concerned with hullform, hull structure, cushion seals, lift systems, resistance, propulsion, stability, seakeeping and manoeuvring.
After more than 40 years of development, the design and construction capabilities are mature and in place here in North America. While much of the technology was developed here, Europe and the Far East have established the competitive viability of commercial applications.
The military applications, particularly for ACV's, have been well recognised here and in Russia and perhaps it is not too late for North America to also realise the commercial potential of the ACV and SES technology that we helped to introduce.
SESSION I
LES VÉHICULES À COUSSINS D'AIR, PRÉSENTATION SUCCINTE
M. G.J. Vernier
France
L'aéroglisseur est le véhicule le plus extraordinaire de nos jours. Ce véhicule amphibie survole à vitesses égales les surfaces solides ou liquides, à fortiori intermédiaires : boues, marécages….
Un bref rappel historique est suivi d'une revue des principes de fonctionnement : sustentation, propulsion, principe de construction. Suivent les applications : Transport, passagers et fret ; Sécurité civile, sauvetage, Garde côtes, brise-glace, surveillance pêche, pompiers ; Loisirs, plaisance et tourisme ; enfin, Applications industrielles.
AIR CUSHION VEHICLES, A BRIEF PRESENTATION
The hovercraft is the most extraordinary craft of our days. This amphibious vehicle flies at equal speed over solid or liquid surfaces, and, a fortiori, over intermediate surfaces: mud, marshes….
A brief historical reminder precedes a review of operating principles: lift, propulsion, construction principles. Applications follow: Transport, passengers and freight; Safety, rescue, coast guard, icebreaking, fishery control, fire; Leisure, tourism; finally, Industrial applications.
(Presented in French)
UTILITY AND SPORT HOVERCRAFT
Mr. R. Rennick
Hovercraft Club of Canada
Light hovercraft have been on the market for a number of years, used for recreation and for racing, but also as utility vehicles to accomplish certain tasks (rescue, light transport, etc) where they can be more efficient than helicopter and, certainly more economical. A non-exhaustive illustrated review is made of hovercraft in the utility and sport category which are now available.
OFF-ROAD TRANSPORTATION IN NORTHERN LATITUDES
Dr. J.Y. Wong
Carleton University, Ottawa
Canada
More than 80 % of the soils in the northern latitudes of Canada may be classified as "humid". This create transportation problems, with have given rise, over the years, to various solutions, including the use of air cushion vehicles.
The paper review the problems of operating conventional off-road vehicles in organic terrain (tundra, muskeg) in the summer and over snow-covered terrain in the winter. The possible role of air cushion vehicles in off-road transportation in northern latitudes is then examined, identifying associated problems. The author then evaluate the feasibility of wheel assisted, or track assisted, air cushion vehicles for northern transportation.
UTILISATIONS DIVERSES DU COUSSIN D'AIR
J.E. Laframboise, AFCASI
Secrétaire, SCTCA
Canada
Généralement, le coussin d'air est vu comme l'outil idéal pour les déplacements sur terrains marginaux (marécages, sols organiques, boues, etc) et le transport rapide sur l'eau, sans égard à la profondeur. Cependant, il existe des utilisations du coussin d'air sur des surfaces dures et lisses, habituellement du domaine de la roue. Ces applications, dans le domaine industriel et dans le domaine du transport sur voie fixe, offrent, en plus d'une résistance au mouvement négligeable, une basse pression de contact, en comparaison avec des pneus ou des roues d'acier, et une installation simple et peu encombrante. Par contre, elles utilisent des pressions d'air élevées, ce qui obligent à tenir compte de la compressibilité de l'air, un facteur souvent négligeable sur les aéroglisseurs légers.
Des éléments de coussins industriels ainsi que quelques applications sont illustrés. L'utilisation du coussin comme élément de sustentation pour trains rapides est présentée et proposée pour une liaison rapide entre les aéroports de Dorval et de Mirabel.
SPECIAL USE OF AIR CUSHION
Generally, the air cushion is presented as the ideal tool to travel over marginal terrains (marshes and other organic soils, mud, etc) and for high speed travel over water, whatever the depth, or lack of it. Air cushions can also be used on hard and smooth surfaces, usually the prerogative of the wheel. These applications, in industry and in guided transport, offer, in addition to negligible moving resistance, low contact pressures when compared to tire or to steel wheels, and rather simple and slim arrangment. However, they use relatively high cushion pressures and air compressibility must now be considered, a factor usually neglected in light hovercraft design.
Industrial cushion elements are presented with a number of applications. The use of air cushions in high speed train is presented. It is proposed for a high speed link between Dorval and Mirabel airports where its use would result in a light and inexpensive elevated guideway.
(Presented in French)
THE CANADIAN COAST GUARD HOVERCRAFT
Captain D. L'Heureux
Canadian Coast Guard
Review of tasks accomplished by the CCG hovercarft in the Laurentian region, with regard to navigation aids servicing, search and rescue and icebreaking on the St.Lawrence River and its tributaries.
History of the hovercraft squadron on the west coast and of the various BHC craft that have been used. Search and rescue, patrol and sanitary evacuations were the main purpose of the squadron, with navigation maintenance work increasing over the years.
Addition of two AP1.88-400 to both the Laurentian and West Coast squadrons will permit development of services. It will also permit retirement of some of the elder vehicles on the West Coast.
SESSION II
HEAVY HOVERCRAFT WORKSHOP
Mr. A. Bliault
Den Haag, Nederland
This is a review of operational experience with heavy hovercraft, primarily AP1.88's but including other types. This addresses particularly maintenance expenditures, with regard to skirts, engines, propellers, hulls and other systems. A summary of the workshop has been presented as the first paper of Session V.
SESSION III
PAR-WIG CONCEPT
Dr. S. Ando
Japan
The paper presents a new concept of power augmented (PAR), wing in ground effect (WIG) vehicle which uses a canard wing combined with an ejector to provide the PAR effect under the main wings of the craft. This reduces both noise and spray. The outer portion of the wings fold up during manoeuvring in harbours under PAR. Characteristics of the wing are chosen so as to minimise induced drag in ground effect. A CL of 0.6 is desirable with an aspect ratio of 6. Flying height is dictated by wave heights over the sea routes. A computer program has been developed to calculate range of craft concepts, 25 and 625 passengers. Calculations show that the 25 passengers craft could be competitive with commuter aircraft.
TAKING STEPS TO PROMOTE THE FAST DEVELOPMENT OF WIG IN CHINA
Pr. Q. Liang, Pr. L. Yun and Pr.
G. Pen
MARIC, Shanghaï
The eager desire of the high-speed passenger water transportation in China is described briefly in this paper. The paper also introduces the features of Dynamic Air Cushion Wing in Ground Effect Craft (DACWIG), and predicates that it will be the one of most hopeful high speed passenger craft in the 21st century. The paper introduces briefly the China made DACWIG type "750" and "SWAN" designed by MARIC. Proposals for taking the steps to promote the fast development of DACWIG in China are also carried out in this paper.
DYNAMIC AIR CUSHION WING
IN GROUND EFFECT CRAFT (DACWIG)
The Prospect of High Speed Water Transportation Tool in the 21st Century
Pr. L. Yun and Pr. G. Peng
MARIC, Shanghaï
Three types of wing in ground effect craft, i.e. power augmented ram wing in ground effect craft such as the Ekranoplane (OARWIG), dynamic air cushion craft (DACC), and dynamic air cushion wing in ground effect craft (DACWIG) are introduced in this paper. Among them the DACWIG is possible to be a very prospective type of high speed passenger craft in the 21st century in the world due to a series of advantages, such as high speed/efficiency, safe, good sea-keeping quality, excellent amphibious and landability, simple equipment, rather low cost, and multi-operation mode. Taking the Shanghai-Nantong route as an example, the economic benefit of the DACWIG is demonstrated.
THEORETICAL INVESTIGATION
OF HEAVE DYNAMICS
Bag and Finger Skirts
Pr. P.A. Sullivan, FCASI, and Dr.
J. Chung, Research Engineer
University of Toronto Institute for Aerospace Studies (UTIAS)
Canada
Although the bag-and-finger skirt is widely used on large amphibious vehicles, there is an almost complete absence of information on its dynamical properties in the open technical literature. This may be in part due to the complexity of the system, leading to difficulty in formulating tractable but realistic models. UTIAS research on this skirt in the past decade has sought to circumvent this difficulty by investigating a simplified configuration: a two-dimensional section of the skirt subject to pure heave inputs. Prediction from non-linear and linear analyses will be presented, together with the results of static experiments performed to date. Of particular interest is evidence that the system can respond chaotically to surface inputs that may be expected to be encountered in practice.
"IRBIS" POWER PLANT CONVERSION
Mr. J.S. Mitchell
Mitchell Research, Port Colborne, Ontario
Canada
The "Irbis" hovercraft is a 32 passengers vehicle designed by NEPTUN, Moscow. It is proposed to remove the two Deutz air-cooled diesel engines and replace them by a single Pratt & Whitney Canada PW205 or 206 gas turbine. The substitution will increase payload by 1 tonne and the added power would permit increasing the cruising speed over the current 40 km/h. Space saved also permit increasing the passenger seat number. In a freighter version, the added power may be used to increase cushion pressure, allowing the "Irbis" to carry a four tonnes payload. A major development item will be in the management of the air delivery to the engine.
A GROUND TRANSPORTATION SYSTEM FOR THE 21ST CENTURY
Dr. W.R. Bertelsen
Aeromobile Inc, Illinois
USA
Aeromobile, Inc. proposes a system of air cushion vehicles in guideways as an alternative ground transportation system. It represents a major paradigm change in ground transportation from the venerable centuries old, but flawed, limited, and problematic, wheels on roads systems. We have demonstrated in full scale, a proof-of-concept prototype, and we are gaining experience in the technology of flying Aeromobiles in cylindrical Right-Of-Way's. Air cushion support of vehicles has many unique and superior attributes which solves many problems impossible with any other system. It is called The Aeromobile-Aeroduct System of Automated Transportation, and should be given serious consideration in this critical era because it:
This new modality of transportation deserves both private and governmental support of further development. There is no other system existing or proposed which when widely deployed, can provide such unparalleled, universal service to all ages, disabilities, and economic status, plus preservation of the planet, its' surface, its' atmosphere, and humanity.
SESSION IV
THE MISTRAL HOVERCRAFT
Mr. W. Armstrong
TSL Aerospace, Mississauga, Ontario
Canada
The Mistral hovercraft is presently at the customer testing phase. Mistral has been designed essentially to have a minimal noise emission. Instead of a propeller it uses squirrel cage type fans for propulsion. Its cushion fans are hydraulically driven from the diesel power plant. Design characteristics of the hovercraft will be given, including observed noise levels attained in the cabin and outside.
BHC AP1.88-400
Mr. A.G. Stanton
Hike Metal Products Ltd., Wheatley, Ontario
Canada
This larger version of the CCG "Waban-Aki" (AP1.88-200) is being built in Canada. One has been delivered to the Laurentide Region of the Canadian Coast Guard and can be inspected during the conference. A second one, for delivery to the CCG hovercraft unit at Vancouver, is now under test. Characteristics of the craft are given. The craft has a cargo capacity of 20 tonnes.
SESSION V
PROCEEDINGS FROM SESSION II
Mr. A. Bliault
Den Haag, Nederland
PERSONNEL TRANSPORT MODULE FOR LCAC
Mr. J. Ducote, U.S. Navy
The U.S. Navy's 81 ft long LCAC can carry a payload of up to 150,000 lb, but was designed to carry Marine Corps vehicles, not a large number of people. The large open cargo deck is ideal for griping tanks, but is inhospitable for people due to salt spray, wind, noise and airborne sand and dirt. As a result, the Navy has developed the Personnel Transport Module (PTM) which and allows carrying of up to 180 additional passengers in a protected environment. The PTM is a pack-up kit, used as needed. The PTM kit can be stored in a single 8 x 20' ISO container. Parts are assembled by hand and all parts are light enough to be handled by two to four people. Assembly time is under four hours, including outfitting. The PTM provides seating with lap restraints, forced ventilation, lighting, and can accept military stretchers to serve as MEDEVAC. The PTM draw 400 Hz power from the LCAC, and can communicate with the LCAC.
LCAC SURF ZONE LANE BREACHING MISSION
Mr. D. Campbell, U.S. Navy
Presented by Mr. R. Teer, U.S. Navy
The implementation of Ship to Objective Manoeuvre (STOM) by the US Navy requires amphibious assault capabilities to be compatible with operations launched from over the horizon. The landing craft and assault craft will launch from support platforms over the horizon and proceed at high speed to the objective area. In order to achieve tactical surprise, mine and obstacle clearance systems will be employed in-stride with the assault forces. The US navy has the requirement to provide cleared transit lanes from over the horizon through the surf zone to support the US Marine Corps amphibious assault forces.
Landing Craft Air Cushion (LCAC) provides a high speed, heavy lift capability to support the concept of (STOM). The LCAC was selected to deliver the breaching systems to the surf zone due to its high speed and payload capability combined with a large open cargo deck. The paper describes the systems deployed from the LCAC to provide cleared ingress and egress lanes through the surf zone. A technical description of the system used for each time domain along with a summary of the LCAC integration and test efforts are discussed in detail.
THE LCAC DEEP SKIRT PROGRAM
Mr. B. Forstell, Band, Lavis
& Associates, Inc.
Mr. D. Vickers, U.S. Navy
The U.S. Navy has a requirement to conduct shallow water mine countermeasure (MCM) operations. Mission involves clearing mines from the 15 ft water depth up through the high water mark on the beach. The LCAC has been the choice of the Navy for this mission. However, the nature of the mission requires that the LCAC be capable of safely operating in the surf zone. It was felt that the current 5 ft cushion depth of the LCAC is insufficient so a program was funded in 1995 to develop a deeper skirt.
The paper describes the overall Deep Skirt Development program from inception through full-scale prototype testing. Technical development is discussed in some details, including trade-off studies and results of scale model testing.
AMÉLIORATION DE LA POUSSÉE DES AÉROGLISSEURS
M. G.J. Vernier
France
La propulsion aérienne des aéroglisseurs permet de profiter entièrement des possibilités amphibies de l'aéroglisseur. Les principes de ce mode de propulsion sont revus ainsi que divers moyens usuels d'augmenter cette poussée. Une comparaison est faite avec les turbofan, et cette technologie est examinée en détail en vue d'une application aux aéroglisseurs. En particulier, le profil d'entrée des carénages doit être adapté au domaine de vitesse de l'aéroglisseur. Divers systèmes sont proposés, variant en complexité.
IMPROVEMENT OF THRUST IN HOVERCRAFT
Air propulsion of hovercraft permits full use of their amphibious characteristics. The principles of this mode of propulsion are reviewed, as well as of the usual means to improve thrust.. A comparison is made with turbofan, and this technology is analysed in detail with regard to its application to hovercraft. In particular, the duct entrance profile must be adapted to the speed domain of the hovercraft. Divers systems are proposed, with varying complexity.
(Presented in French)
SESSION VI
LES AÉROGLISSEURS SPORTIFS EN EUROPE
M. P. Lépicier
France
Une introduction historique expliquera la création des règlements des championnats nationaux et du championnat européen. Notamment la formation de "team" scolaire en Angleterre qui a permis d'augmenter avec de jeunes pilotes le nombre de pratiquant dans ce pays.
Suivit de l'explication des principes de base de fonctionnement des aéroglisseurs léger utilisé en compétition, puis on étudiera les différentes solutions techniques retenus et développés dans les quatre pays européens les plus actifs (BE, FR, GB, DE). Seront analysées les solutions de transmission, de jupes et les types de propulseur. Ce qui amène à une comparaison avec les techniques utilisées en Amérique du Nord. Suivra une description d'aéroglisseurs utilisant des moteurs quatre-temps, qui permettent de se rapprocher des diverses normes de pollutions et, surtout, de bruit définis dans les réglementations auxquelles les aéroglisseurs sont soumis.
Pour conclure il sera présenté des utilisations autres que la compétition pour lesquels les aéroglisseurs légers sont employés, notamment les utilisations en plaisance (sorties en rivières, raid).
SPORT HOVERCRAFT IN EUROPE
A historical introduction explains the creation of regulations for national championships and for the European championship. Pilot distribution in Europe is lead by England where the organisation of school teams brings young pilots, thereby increasing the number of pilots in that country.
Explanation of the operating principles of the light hovercraft used for competition follows, with a study of the various technical solutions used and developed in the four most active European countries (BE, FR, GB, DE). Analysed are transmissions, skirts and propulsion. Which brings a comparison with the techniques used in North America. Four cycle engines are now being used in sport hovercraft as they permit a closer conformity to the various regulations concerning pollution and, particularly, noise to which hovercraft must submit.
In conclusion, uses other than competition are presented for light hovercraft, principally for leisure (raids, river outings)
(Presented in French)
THE REVTECH ROCKET - HORIZONTAL ACCELERATION
Mr. O. Ellis, Rev-Tech
Australia
The RevTech Rocket M1 is a small two place sport hovercraft with a technical rather than commercial agenda. The craft's seemingly conventional exterior hides an advanced composite structures and innovations aimed at improving operating efficiency and safety. Performance and stability were the primary design objectives. Improved performance was achieved by both weight reduction and thrust increase. The Rocket hull is not only stronger and more durable, but is half the weight of conventional glass reinforced plastic hulls. Thrust was increased by both the development of a larger fully aerodynamic hybrid fan duct featuring a segmented radial splitter plate and the fitment of a high efficiency engine and drive components.
Improved stability was addressed in two ways. First, a shallow, raked, forward planing surface was incorporated into the lower hull. To maintain the correct skirt geometry, a forward skirt attachment deflection panel system was fitted. Second, a dual path, priority lift air supply, that ensures increased airflow and pressure to the forward segments was developed.
Evaluation of the craft has shown that the increased performance provides significant improvements in control and maneuvrability, as well as reduction in noise and greater fuel economy. The skirt deflection system and the priority lift air supply have eliminated the traditional problem of plow-in. The composite hull has proved to be very tough and robust in service.
Last update/ Révision : 99.05.27