HOV-G CRAFT & HYDROFOIL

THE INTERNATIONAL REVIEW OF AIR CUSHION VEHICLES AND HYDROFOILS

KALERGHI PUBLICATIONS can your defence strategy succeed without the world's latest weapons system ?

. . . the BH.7 which brings a version (FAC) and the logistic mobile, easily-concealed shore new dimension to your amphibious version (LAC). bases or from mother at sea. defence planning. BH.7 has a lot to offer. Only BHC hovercraft have been This 40-ton pacesetter is now With its 3,400 s.h.p. Rolls-Royce used in combat. On operations on offer with firm delivery Marine Proteus gas turbine, BH.7 with both British Defence Forces dates and prices. Already the is a completely integrated weapons and the U.S. Navy they have British Government has system carrying formidable fire proved themselves in every climate announced its intention to power at a cruising speed of from tropical jungles to the frozen order both the fast attack 75 knots, by day or night from arctic.

BRITISH HOVERCRAFT- WORLD LEADERS IN THE HOVER REVOLUTION

BRITISH HOVERCRAFT '& CORPORATION LIMITED ISASUBSIDIARY OF A'RCRAFT w,,,,.. ~ ..*...,,,",,$* LIMITED .h".m,.'*, #,",,,** AUGUST1967 VOL 6, No 11 Editor : JUANITA KAURGHI HOVERING CRAFT AND HYDROFOIL iis produced by Kal~rghiPublications, 50-52 Blandford Street, London, PVI. Telephone WELbeck 8678. Printed in Great Britain by Villiers Publications, London, NW5. Annual subscrip- tion: Five Guineas UK and equivalent overseas. USA $15 There are twelve issrres ann~mlly, Contents of thi,s iswe are the copyright of Kalerghi HOVERlNG CRAFT Publications. Permission to reproduce pictures and text can be granted only under written ugreement. Extracts or comments may be made with due acknowledgement & HYDROFOIL to Hovering Craft and Hydrofoil.

FOUNDED OCTOBER 1961 ADVERTISING REPRESENTATIVE L. Temple Rosswick Ltd, 3 Queens Court, Queensway, London, W2. Telephone BAYswater 5812 First Hovering Craft & Hydrofoil Monthly in the World l1 PAINS HAT will the Ertimates Committee of the House of concern are natural. But the soundness of establishing Commons be saying in ten years' time about hover- Ministry superv~sionover the whole hovercraft field, in- craft research and development? The question, impossible cluding the hovercraft respons~b~litiesthat used to be though ~t may be to answer, is worth asking in the light of borne by the old Ministry of Aviation, is not open to the recent Estimates Committee report on the British space serious question. Overlapping, duplication of effort, finan- programme. cial waste-curses of the space and other technological The Committee sharply criticised the Treasury for un- programmes - should be largely averted. willingness to consider space research as a whole. It There will of course be a period of uneasy adjustment proposed that one Ministry, the Ministry of Technology, by HDL and the hovercraft officials from the Aviation should be made responsible for all space research. Too Ministry on the one hand and Mintech on the other. many Ministers, the Committee clearly felt have had their Technologists do not Ilk* the idea of becoming bowler- fingers, in the pie up in the sky. There had been wasted hatted bureaucrats, even with civil servlce security of opportunities, lack OPI purpose, an absence of cohercnt tenure. They prefer more pay, less formality and even the ri~kof the sack. Established civil servants, for their part, organisation. are not always sensitive to the individual quirks of gifteci With any luck there should be no such strictures on the "boffins". Willingness to make the marriage work is needed hovercraft programme when the Committee of Estimates by both parties to the match. reports in 1977. The industry and the Government can Fortunately Mintech is young and supple. There is a congratulate themselves that hovercraft development has, long way to go before arteries harden. And Mr Wedgwood at an early point after its successful launch, been brought Benn is the unstuffiest of Ministers. There is good reason under the central control of a single Ministry, Mintech. to expect that he will know how to work the HDL men There may be wasted opportunities ahead, but alniost cer- smoothly into h~steam. tainly not lack of purpose or organisational incoherence. The discontent expressed at HDL over the terms of Many people in the industry have voiced grumbling their joining Mintech will not last long, if the Minister suspicion about the "take-over" by Mintech of Hovercraft acts wisely. They will forget their suspicions once they see Development Ltd. The scientists and engineers at HDL how much they stand to gain from central, purposive are, in particular, concerned about their new status and direction. The troubles at HDL are growing pains but conditions as civil servants. Both the suspicion and the there is more growth than pain ahead.

IN THIS ISSUE The Hovercraft Pioneers 4 Improvement in Foilborne Navigation 19 People and Projects 6, 23, 30, 32 Expo 67, Canada 20 Power for Hydrofoils 8 Hydrofoil or Hovercraft ? 24 Moving Day 14 Hovertravel 28

COVER PICTURE : Waiting to take to the water for the first time, the US Navy hydrofoil gunboal, PG(H)2 "Tucumcari", hangs suspended during its oFcial launchirtg and christening ceremony. More than 500 gue~tswitnessed the launching of the Navy',, newest hydrofoil, which is designed to cruise cct a speed of more than 40 knots. The launching took place at Seattle, Washingtort, jocilities of the Boeing Company, who designed and built the hydrofoil (See People and Projects, page 6, for further details)

drove the prcnlc party ~ntoa packed transport cafe. There "wrth the julte box In full swmg" Hovermarrne's directors declded to spend therr "last few bob" on enterrng Hover- show 66. Aboutthrs trme, Tattersall had recelved temptrng offers of jobs In the Un~tedStates; and he mrght well have gone but for thrs Hovershow declsron, whlch "turned the corner for Hovermarrne". Here, the company met rts first major shareholder, who put rn sufic~entmoney to start the company on rts own "garret" premlses in August 1966- two 18 feet square attrc rooms rn ult~mately housrng erght people. Among the early team was Davrd Nicholas, now per- sonal assrstant to Ted Tattersall. HIS enthusrasm, en- couragement and sheer hard work has been an essentral factor In spurrrng the project along. Davrd came from HDL and was a key member of the s~dewallteam there. Peter Hrll, the company's productron manager, jorned at this tlme and has consrderable experrence rn rernforced plastic structures. He was prev~ouslyemployed by Walmatlc Ltd. Another "volunteer" was Shlrley Fellows, who pro- v~dedall the secretarral work. Shlrley was prevrously Mr Cockerell's secretary at HDL. By December 1966, Hovermarlne had promrse of a further major shareholdrng whlch enabled Tattersall and hrs desrgn team lo embark on the detall desrgn of the first Hovermarrne product~onvehicle, the 60 passenger HM 2 now under constructron In Halmatlc's workshops. At this trme, Tattersall brought In Bob Tr~llofrom HDL as chref development engineer "to think of tomorrow's products" and to take the deep-cushlon concept further. "This concept, we feel, is as important a step as the introduction of flexible skirts," says Tattersall, who is de- termined that "development of the idea to fruition shall take place within these shores". To get development under way, the company must raise the not-so-very-large sum of 2250,000 and Tattersall says categorically "The country should support this". Some monies were allocated to the In 1963 thrs group of enthusrasts schemed out a proposal defunct Denny D.3 project and "1 feel we should inherit whrch ultimately led to the formulatron of the Hover- the right to use this money". marrne 30-seat craft - the companys first "brochure" srde- One of the attractive characteristics of Ted Tattersall is wall project. A common determrned Interest was apparent his reluctance to "oversell". Speakrng of the 60-passenger and eventually Hovermarrne Ltd was formed rn September craft he says "it won't revolutionise anything", but on the 1965 The founder members wele N D. Prper, G. C. rrght routes it should prove profitable. With unlimited Hodgson, H M Watson, E G Tattersall - J D. C. Stone funds, Tattersall would have concentrated on a larger craft was company secretary and IS now the financral Dlrector - "the sooner we get on wrth the deep cushion concept, At the end of 1965 Tattersall left WDL so as to get the new the better" and the current 25 ton HIM 4 deep-sidewalI company's projects under way. Chrrstopher Coclterell pro- project, although a useful craft in its own right, he sees vrded a very sympathetic ear and was a source of frrendly primarily as a half-scale model for a high-speed 1,000 ton advlce at this rather crrtrcal trme. Although Cockerel1 drd freighter craft for containerised cargo, wlth a 16 ft wave not agree wlth all the Issues, he accepted that Tattersall capability, probably powered by combined dresel and gas was determrned to do somethrng about sldewall craft turbine installation. He also sees the deep-cushion sidewall At thls stage Hovermarrne had no headquarters; Ted was configuration as a "natural" for hoverships and large workrng at home In the spare bedroom and board meet- transatlantic vessels. rngs were held at weekends Among the toprcs discussed at these cornpany meetrngs was the need to ~ncreasesea- Ted Tattersall has great confidence in the future for going capabrlrty and to elrmrnate the flat bottom of British hovercraft - and in his own contribution towards present hovercraft, whrch 1s lrmlted In cushron herght partly the future. He has had need of that confidence in the by stabrlrty consrderatrons. From these d~rcussrons Ted immediate past when Hovermarine's efforts to acquire a evolved the deep-cush~onconcept, rn whlch the payload licence continually came up against a solid wall of frus- IS carried wrthln the srdewalls, together wrth the propul- tration; and he will probably continue to need it to slon system and fuel Thls allows the cush~onto be ralsed, over the potential obstacles that lie ahead: but there is provrdlng greater over-wave clearance wrth negllgrble effect plenty of cushion power and directional stability in this on centre-of-gravrty helght. Tn March 1966, Hovermarme young man and his co-directors. appl~edfor patcnts for the deep-cushron srdewall craft, rn Each and every member of Hovermarine's team was several countries, Edward Gunston Tattersall is clted as initiated at an interview which in the first instance was the lnventor aimed at discovering their voluntary enthusiasm. Each has On one occasion a board meeting was combined with a accepted the challenge; each is determined to make the family picnic on the Hogsback, but disastrous weather project a success. Champagne foamed over the bow of the Un~tedStates T. Desmond Earl, project director and co-~nventorof Navy's newest hydrofo~lvessel in launch~ngceremonles at the ACLG, expla~nedthat the a~r-cushionbag is activated the Boeing Company, July 15th, In Seattle, Wash~ngton. by a fan that Bell engineers Installed In the hollow rear Seconds later the gleam~ngsteel fo~lsof the PG(H2) (patrol fuselage of the . To prepare for landing, the pilot gunboat hydrofoil) dlpped Into the water for the first tlme starts a small, four-cylinder englne that powers the axial Mrs Ph~ll~pB B~dega~n,spon\or of the vessel for the fan. When he 1s ready to Inflate the ACLG, the p~lotpulls Navy, chr~stenedthe advanced 71-ft craft Tucurntavi for a lever to ~ts"inflate" position. The "rnflate-deflate" Lever her New Mexrco hometown wh~lemore than 500 guests controls two sets of louvres in the aircraft's fuselage. In watched the "inflate" position, louvres lead~nglo the ACLG are Pr~ncipalspeaker was Rear Adm~ralJohn D Bulkeley. opened and louvres on the s~deof the fuselage are closed. A PT boat sklppei and Medal of Honour winner dur~ng When the lever is In the "deflate" position, the louvres World War 11, Adm~ralBulkeley recently was appointed reverse the~rpositions The side louvres are designed to pres~dentot the Naval Board of Inspect~onand Survey rn give the airplane forward thrust when the ACLG is in Wash~ngton,DC the "deflate" mode w~ththe fan englne on. Guests were welcomed to the launch~ng by Boeing The most dist~ngulsh~ngfeature of the ACLG is its Prestdent Wlll~am M Allen Lysle A Wood, Eoe~ng's landing gear "bag". When ~t is inflated, alr from the fan Group v~ce-president- Aerospace, served as master of engine escapes through hundreds of jet nozzles that circle ceremonles the bag's undersrde. These jets of air feed inward toward The launching guests Included Navy representat~ves.New the "hole" of the ACLG doughnut, producing an air Mex~codrgn~tar~es, representatives of the Pac~ficNorthwest cushion under the alrplane that holds ~t off the ground. marine industry, Boe~ng executives, and the Boerng Bell developed a special material for the ACLG bag. employees who designed and bu~ltthe advanced craft It cons~stsof layers of nylon cloth sandwiched between Leading the New Mex~codelegat~on was Congressman layers of rubber. Th~smaterial stretches easily to triple Thomas C. Morris Mrs Morr~swas Mrs Bldega~n'smatron its width, but can't be stretched lengthwise at all. [n land- of honour. Ing with the ACLG, the plane's forward speed is checked In contrast to most sh~plaunch~ngs, the Tucun~curl by reversing the pitch. For final braking, the air- hydrofoil entered the water as a nearly completed vessel cushlon bags rubber rrbbed tread 1s brought into contact ~ns~deand out Tt will undergo dockslde testing and hull- wrth the ground by a braking control. borne manoeuvvzk,, followed by ~tsfirst "fl~ght"on ~tsfolls Because the ACLG bag 1s flexible, ~t conforms to ground In September at qpeeds of more than 40 knots contours and can pass over obstacles. Bulldozers, in an Des~gnedand bu~ltby Boeing, the Tucurncarl represents emergency, could rough-grade an airstrip and giant cargo a s~gn~ficantdevelopment In hydrofo~l des~gn.The craft planes fitted with ACLG could begin landing immediately. has no conventional propeller and will use a unlque system Earl said one of the best features of the ACLG is that of waterjet propuls~on Its system acts as underwater rt does not need a hard-surfaced runway. "wlngs", l~ft~ngthe craft's hull above the water, enabl~ng "The weight of the plane is spread out over the rela- ~t to ach~evehigh speeds and great manoeuvrability In tively Large area covered by the bag," said Earl. "Because almost any type of sea. of this, only a small amount of air pressure is needed lo It will undergo extensive fo~lbarnetests prior to dellvery hold the craft off the ground." to the Navy late th~syear. In Bell's test airplane, this air pressure totals 50 Ib/sq ft, * * * or less than ) Ib/sq in. In contrast, a wheeled airplane puts Textron's Bell Aerosystems Compariy has announced all its weight on the small surface where its tyres touch that it has successfully flown an airplane that lands and the runway. Thus, the ACLG airplane can use open takes off without wheels on an air-cushion landing gear. water, ice, snow, swampland, sand or dirt for most run- The flight took place recently at Niagara Falls lnter- ways. Only its actual debarking, service and terminal area national Arrport. would have to be surfaced with concrete for use by The airplane in which the Air Cushlon Landing Gear service vehicles. (ACLG) concept was proved was an LA-4 "Lake" amphi- The test aircraft IS propelled by a standard 180 hp prston bian that Bell engineers modified and equipped with an engine. Gross weight of the craft, w~ththe ACLG, is air-cushion system. 2,400 Ib. The ACLG fan engine weighs 72 lb and turns the With Bell test pilot David W. Howe at the controls, the 2 ft dranieter fan at up to 4,100 rpm. craft took off, circled the and landed on its air Earl said the test ACLG weighs little more than a stan- cushion. The plane behaved much as it would with dard landing gear. ''In a larger airplane," sa~dEarl, "the wheels. Howe said later that the air-cushion take-off and weight of the ACLG might even weigh less than conven- landing were "smooth as silk". During the flight, Howe tional gear." radioed the words: "Bag down and inflated." This phrase In flight, the ACLG has no effect on the performance may someday join "gear down and locked" as the stan- of the alrplane On landing and take-off, Howe sa~dit was dard airplane-to-tower commullication just before landing. impossible to tell just when the air-cushion support left off. When it is inflated, the ACLG looks much like a 2 ft Bell has patented the ACLG concept (US Patent No thick black doughnut on the plane's underside. In flight, 3,275,270). Co-inventor with Earl, and named in the patent, the ACLG hugs tightly and aerodynamically to the is Wilfred J. Eggington, Bell's air-cush~onvehlcle derign aircraft. technology chief. Earl said Bell will continue to modify and lmprove its at Boeing from 1955 to 1960. Following that he was ACLG airplane, wlth additional flights planned for later D~rectorof Search and Evaluation for Boeing Associated this year. The Initla1 ACLG airplane is a test bed intended Products. to prove the air-cushion landing gear concept and lead the Wood said Air-Go's product development will exploit way toward its application in military, commercial and the numerous uses of a flexible, inflatable air bearing cargo . which lifts objects from the ground and holds the trapped Last year Bell received a $99,000 contract from the Fl~ght bubble of air pressure on which they float. The bearing Dynamics Laboratory at Wright-Patterson Air Force Base, will be an integral part of both self-propelled devices, and Dayton, Ohio, to do wind-tunnel tests of ACLG models. of pallets which w~llfloat heavy objects by the use of air More recently, Bell received a $98,700 contract from pressure from a self-contained or outside source. Wright-Patterson to build a ground test model to study "We intend to make commercial applications of this the possible use of the ACLG on a C-119 "Flying Boxcar" new air-cushion technology where ever possible," Wood cargo airplane. sa~d."There are promising opportunities for Air-Go to * * * achieve a leading position in the air-cushion industry. We The prlnclpal character~st~csof the two types of hydro- feel the company can become an important economic foil boat produced by Seaflight S.p.a. of Messina (see page factor in this reglon." 1 %of thls ~ssue)are as follows : Wood said the firm wlll conduct design engineering, "P.46" "H.57" development and marketing with a small Initial staff in its (30 pass.) (60 pass.) offices at 2447 Sixth Avenue South. Construction of pro- Length 0.a. 46 ft 6 ~n 57 ft 1 ln duct components will be sub-contracted to local firms. Breadth over fo~ls 16ft 51n 26ft 3 ~n While attempts at commercial exploitation of air-cushion Draught (float~ng) 5ft l11n 8ft11n devices have been under way for some time, Air-Go is the Draught (on folls) 2 ft 6 ~n 3 ft 8 ~n first-known company established to concentrate its total D~splacement: effort in the field. Full load -tons 12.5 26 The firm's initial objective will be the perfection of D~eselenglnes - hp 2x370 2x650 small devices, such as materials-handling pallets, rather Cummlns Flat-Carraro than the better-known "hovercraft" types of vehicles. Take-off speed --knots 20 20 First potential customer for such pallet systems is the Crulse speed up to --knots 35 35 aircraft industry, Wood said, with airplane assembly the Max~mum speed - knots 4 1 3 9 first probable use. A set of five 8 ft by 10 ft pallets, each Range - naut~calm~le~ 270 270 supporting up to 45 tons, can move sections of a plane as Sea-state - No 2-3 3 -4 large as the 350,000 1b Boeing 747 through final assembly, Wave-helght - ft 3 5 he said. * * * Air-Go will also proceed with tests on air-cushion pallets Formation of Air-Go Inc, a new firm which will develop designed for loading airl~nerswith cargo and food galleys. and manufacture air-cushion devices, has been announced Standard aircraft cargo pallets would be fitted w~thflexible by a group of prominent Seattle businessmen. air bearings. Compressed air from a source outside the The Seattle corporation will produce a variety of plane would be fed into an inflatable plenum distribution materials-handling equipment designed to "float" over system built into the pallet. ground and water surfaces on a frict~on-eliminatingfilm or Wood said the air bearing invented by Crowley has cushion of air. substantial advantages over those developed for previous Officers of the new firm are Stanley B. McDonald, presi- air-cushion devices. "It allows you to float and move dent; Kenneth G. Wood, vice-president and general objects with a lower coefficient of friction, greater stabil~ty, manager; Fred Kimball, treasurer; Wheeler Grey, secre- and much smaller air requirements," he said. tary; and WiI Anderson, assistant secretary. All except "This bearing is compact, light in weight, and tremen- 1 Anderson are members of the hoard of directors. dously efficient," Wood said. "Attached to a pallet mea- Other directors are M. Lamont Bean, Robert J. Behnke, suring about 3 ft by 4 ft and inflated by a small blower, it W~lliam Caswell, Robert Halliday, Rogers P. Holman, can easlly float a 2,000 1b load which a person can control William S. Leckenby, Gregg C. MacDonald, Phillip S. by hand." Padelford, Rlchard C. Philbrick, James C. Pigott, Hugh A. There are numerous other possibilities for use of the 1 Smith, and T. Evans Wyckoff. Air-Go bearing in industrial materials handling. They Air-Go Inc IS being created with co-operation of the include the floating of retail displays, moving merchandise Roeing Company. whose Associated Products Divislon is in warehouses, and loading and unloading of truck-trailers largely responsible for preliminary development of the and ships. major air-cush~oncomponent the new company will per- "We also see air-cushion applications in the consumer fect and market. Boeing has licensed Air-Go operations household field," said Wood. and will retain a financial investment in the firm. One is a pallet designed to move large household appli- Two Air-Go pr~ncipals, Kenneth Wood and inventor ances and furniture during cleaning, painting, and moving. Walter A. Crowley, will direct design and development. A standard household vacuum cleaner supplies enough air They have been associated in air-cushion research at to easily float a refr~geratorweighing up to 1,000 Lb. Hoeing for several years and are experts in technology of Air-cushion vehicles offer some of the most interesting the field. possibilities for both civilian and military use, Wood said. Crowley is inventor of the first US man-carrying air- They include land and amphibious sports machines, Aying- cu~hionvehicle, now displayed in the Smithsonian Insti- pallet riding toys, amphibious commuter vehicles, and tute, and holds several other a~r-cushionpatents. As a sub-sonic transit trains capable of all-weather safe speeds design engineer, he has specialised In research on ground of 200 mph and above. effects devices for the past eleven years. * * x * Wood was head of various facility engineering functions (Continued on page 231

SURFACE PiERCfWG CBWBIWEll

Range of engines available-con-

COMBlllED SURfbCE PIERCING AN0 SURFACE PLARlMG SUBMERGED

Figure I. Table gives a comparison between the pricipul Figure 2. Variations on submerged and surface-piercing foils. characteristics of high-speed diesels and gas turbines. Photo Of the two basic types8, submerged foils have better riding left shows Proteus-powered PC(H)I rising on its foils qualities in high seas than the surface-piercing type

Lightweight marine gas turbines have already become strongly established in high-speed. displacement vessels and hovercraft. A third role of growing importance is that of power- plants for hydrofoil craft. In this article Mr Connor discusses some of the problems involved in the design of hydrofoils and summarises the Rolls-Royce Industrial and Marine Gas Turbine Division's participation in the supply of gas turbines for these vessels. Much of the information contained in this article originally appeared in Navy, with whose permission it is reproduced here.

YDROFOIL craft themselves are not new; the first was The Foils H built and operated before the turn of this century, Fig 2 presents variations of the two different types of and through the early decades of the century various foil configurations, surface-piercing and submerged. Of the experimenters constructed and "flew" hydrofoil craft, some- two basic types, the surface-piercing configuration has times with amazing performance. These craft had a wide poorer riding qualities in high seas than the submerged foil variety of hydrofoil strut configuration. configuration. However, the full scale sf this concept of craft has Craft with a surface-piercing foil system react to wave awaited the development of several new technologies, action with a change in the amount of foil area exposed to namely : water, thus automatically adjusting the foil's lift. This tends I. Engines with very high power-to-weight ratio. to increase the craft's altitude when entering a wave and 2. High-speed, high-efficiency foils. decrease the altitude when leaving it. 3. High-speed, high-performance . 4. Gear transmission systems of very light and unusual Craft with a submerged foil system cut through smaller capabilities. waves that otherwise come into contact with the hull. To 5. Water-jet propulsion. accomplish this contouring, however, such craft need con- 6. Boat hulls of aircraft-type construction. trol equipment. ?'he result is an inherently more expensive All of the required new technologies have been developed system implying as it does, sensing, comparing and servo to a very promsing state and a summary is given below. elements which are naturally sophisticated, but it also results in a greater potential for sea-keeping. Most of the Powerful Engines commercial craft in service today use surface-piercing foils. The hydrofoil, like all high-speed craft, requires a reason- able low specific engine weight. It was realised that as the Present-day experience indicates that submerged-type size of the craft increased, the power of the largest exist- foils with automatic control will excel the surface-piercing ing high-speed diesel engine would not be suitable in larger types. However, a hybrid system now under investigation, vessels, neither would conventional marine diesels, steam namely surface-piercing with automatic controls, may turbines or steam engines because of their high weight. approach the performance of the all-submerged types. This left only the lightweight marinised aero-type gas turbine. Gas turbines for foilborne operation make possible Propellers large craft and high speeds. They develop more power per The marine propeller becomes a marginally satisfactory unit space and weight than any other engine. thrust producer under the high speed and power require- Lightweight diesel engines are available today only up ments of hydrofoil craft. Speeds above 45 knots will norm- to approximately 3,000 hp continuous rating. Marine gas ally dictate the use of supercavitating propellers. Problems turbines are available up to approximately 20,000 hp con- in the design of supercavitating propellers include blade tinuous rating. strength and losses, due to cascade effects. Some recent The availability of high-power gas turbines is a very failures were of a fatigue nature. It is thought that thicken- important factor in designing larger craft where greater ing the sections or using better material may solve the cur- powers are needed. Multiple amounts of smaller engines rent problems. A great deal of work needs to be carried normally add complexity and weight. Fig 1 gives a com- out to enable the use of supercavitating propellers with parison between high-speed diesels and gas turbines. complete confidence. li Figure 3. Wuter jets huve been studied as an ulternutrve tlzrust- producing system to tonventional propellers. Tlze simplicity of Velocih (Knots) wnter jet propulsion i~ very attractive

Figure 4. Typical eficiencie~of various meikods of thrusl pro- duction. The wrrfer jet is con~parublewith the supercccvitatiing Gear Tra~~smission propeller between 65 and 100 knots Most of the early hydroforl boats used an rncllned pro- peller shaft. The drive to the shaft has been accomplished Flg 4 compares the typlcal eficlencles achreved by by such means ar an inclined engine, an angle drive by varlous methodr of thrust production. The water let has a means of universal couplings or by Vee-drive gearboxes. fairly constant efficrency at speeds above 50 knots; ~t 13 However, the extension of this drive into larger vessels, comparable w~ththe supercavrtat~ngpropeller at speeds with higher speed and with the ability to operate in the from 65 to 100 knots Atlantic Ocean, poses some very serious engineering prob- The water-jet system wlll weigh less than a comparable lems. Zt is hard to get a craft of this type high enough off supercavltating propeller system and should be cheaper rn the water to accommodate high waves. The propeller thrust rn~t~alcapltal cost, more relrable and easrer to operate and is not in the proper direction for the highest propulsion malntaln. There IS no complicated power transmission efficiency. The long-drive shaft from the power source to system and no lubrlcatlon problem associated with keeplng the propeller Is a vibration hazard. Furthermore, it 1s hundreds of moving transmrsslon parts running smooth impossible to retract the inclined propeller type of drive. The water-jet englne I? connected darectly to the h~gh-speed For most efficient cruising in the displacement condition or pump The installation 1s compact and eaqily accessible. operation in shallow harbours, or for cleanlng the foil system, a retractable drive is necessary. Boat Hulls of Aircraft Type A perpendicular drive with two 90" power gearboxes Atrcraft technology has understandably had a strong offers the opportunity of considerably extending the use of rnfluence on the recent developments In hydrofoll craft. hydrofoil boats. 77he strut and foils that contain the main The techn~quesof aerodynamic design have been applied drive gears can be readily retracted without affecting the dlrectly to hydrofoil systems. Apart from alrcraft gas integrity of the transmission system. turbrnes mentioned above, aircraft autop~lottechnology Since the hydroforl craft is analogous to an aircraft, ~t is has been used to deal wrth problems of hydroforl craf i necessary that all major structural elements be very light in control. Aircraft structural deslsn techniques here had a werght. Gear materral that does not contribute to the per- strong influence on hull and foil construction Alrcraft concept? of equ~pmentand machinery I~fe,rel~abllity aid formance and rellabillty of the transmission must be eliml- nated. Because of thrs the welght of hydrofoll gearing 1s of malntenance are influencrng hydrofoll operating concepts the order of one-fifth to one-tenth of conventronal marine which In turn exert a strong influence on deslgn gearlng. However, rt must be realrsed that transmlttlng It is, therefore, not surprrslng to find alrcraft companies 10,000 to 20,000 hp by meails of such gearing from a gas deeply lnvolved rn the development of hydrotolls turbine rotatlng at 5,000 rev/mln presents formidable engineering problems State of the Art Without doubt, the Unlted States Government IS at the Water Jet Propulsion forefront in the development of such craft Both the Marl- Because of the difficulties experienced on propellers trme Admlnistration (Crvil) Authority and the United operating in the cavitating reglon and by transmission of States Navy have been spending considerable amounts of high powers to propellers, other schemes of thrust have money in research and development. About seven years been studled, such as arr propellers, straight jet engines and ago the Navy accelerated lts programme of hydrofoll water jets. The most promising of these schemes appears to development The reason for thls increased emphasis was be the water-jet system. Fig 3 shows a schematic layout of related to the des~reof the Navy that the hydrofoll would such a system. Water is taken through an inlet at the provide a more effective sh~pfor dealrng wlth the hrgh- bottom of the strut and up to a gas-turbine-driven water speed nuclear submarine pump. The water is then expelled through nozzles in the Therefore, the emphasls moved to hydrofoll craft able transom of the craft. The srmplicity of this system is very to perform In open seas and to lncreaslng speeds beyond attractive. the conventional limit of approx~mately50-60 knots Figure 5. Arrnrlgemel~t of the maclr~nery in PC(H)Z. Power Figure 6. General fllrflG'ement of the foils and propeller~ in slzafts lecrd for~,urd and drive via bevel gears to counter- PC(H)l. TO meet foilbort~erequircmertts the craft uses u sub- rotating propeller J. Ethaust is dischtrrged directly uft merged foil system with aictomutic controls

USS High Point on more than 4,000,000 hours of service running. The marine version of the engine has proved extremely success- In 1958, the Bureau of Shlps began the deslgn of the ful in fast patrol boats and motor gun boats, and more first Unlted States Navy operational hydrofoil patrol boat, than 110 Marine Proteus have been delivered to, or are on USS Nzgh Poznt PC(H)l. This sh~pwas to perform rn- order for, seven of the world's navies. The most recent shore anti-submarine duties and, in addition to ~tsability order for the Royal Navy is for the frigate Exmouth, to go at hlgh speed in rough waters on its foils, it was which will use two of these engines for cruising. Qpera- required to have a fairly long range and excellent sea- tional experience with the Marlne Proteus at sea now keeplng ablllty In the hullborne mode of operation. The exceeds 30,000 hrs and is increasing at the rate of 7,000 hrs contract for thls 108-ton craft was placed on the Boeing per year. Alrcraft Company and the speed requirement was stated as Because it is a development of an aero'gas turbine the 40 knots Marine Proteus is light and compact for the power The follborne sea-state requirements were so stringent developed. It incorporates a free-turbine layout in which tor a craft of the slze contemplated that it was declded the turbine which drives the power shaft is independent of that only a submerged foll system wlth automatic controls the compressor system, so that the engine delivers extremely could provlde the performance demanded. high power at low and medium propeller speeds. This For hullborne operation the struts In the foil system allows rapid acceleration and gives great flexibility of per- retract vertically ~ntothe hull, thus reduclng draught. formance. The engine gives full power in less than two Inspection, cleanlng or other maintenance of the folls and minutes of a cold start. struts can be done ollly by divers or by dry-docklng. The automatic control system for High Point receives Gecrnali Navy -Hydrofoil Plans craft motion input from a sonic height sensor at the bow and from roll and pitch gyros and vertical accelerometers. The German Navy are extremely interested in this new The computer portlon of the control system then transmits concept of craft and have bought two Marine Proteus signals to control the hydraulic actuators, which move the engines to power a prototype Supramar-designed hydrofoil flaps on the forward and after foils to maintain height, of approximately 160 tons. All other information on this pitch and roll attitudes within very close limits. The control project is restricted at the time of writing. system also limits the vertical accelerations and orders con- touring of waves too high lo avoid hull contact. It also US Navy's Hydrofoil Grinboats permits banking in turns to reduce side loads on the struts. Gas turbine propulsion plant has also been designated Power is supplled by two 4,250 hp Marine Proteus gas to power the 's new hydrofoil gunboats. turbine engines which are located aft, taking air down the Two craft are at present under construction. The first, trunks used to house the retracted strut and discharging known as PG(H)l, has been designed by the Grumman exhaust directly aft through the transom. The power shafts Aircraft Corporation and is powered by a Tyne engine. lead forward to right-angle bevel-gears at the top of each The second craft, designated PG(H)2 (Fig 8), will be strut, down each strut with a single shaft to right-angle powered by a Marine Proteus engine driving a revolution- gears in a propulsion pod and then to counter-rotaing pro- ary water jet propulsion system. The designers of this craft pellers at each end of the propulsion pod. Counter-rotating are the Boeing Aircraft Company of Seattle. propellers were selected to reduce the gear size and hence PG(H)2 will fly on three fully-submerged foils similar the pod diameter. Figs 5 and 6 show a schematic machinery to those on High Point. Water is drawn into the rear struts layout and the craft at full speed. by the Proteus-driven pump and is discharged at high speed The Marine Proteus (Fig 7) is a development of the through stern nozzles which are above the water line. The Proteus turboprop which powers the Britannia , in will have a speed in excess of 40 knots and will be which it has gained a remarkable record of reliability based the first of its kind designed for Navy service. Figure 7. 3ectior.t drawing of the 4,250 lzp Marine Proteus gas Figure 8. The PG(H)2, one of the 7Jnited States Nuvy's r?ew lurbine, operc~tional experience with which itow) exceeds l?ydrofoil gunboats, will be powered by a Marine Proteus 30,000 hours in fast patrol bocrts mzd gurt boats driving a water jet propulsion systeirr

Figure 9. Studies indicate that hydrofoil ships with displacements between 500 and 3,000 tons are feasible. Marine Olyn.lpus irzstallation would be s~iitablefor such vessels Principal data on the two craft are : Grummutz Boeing Length 74 ft 01n 71 fl 10 in LEOPOLDO RODRIQUEZ Beam 21 ft 0 in 19ft61n Draft SHIPYARD Foils extended 13 l't 5 in 13 ft 11 in Folls retracted 4 ft 3 ~n 4ft 5 in MESSINA - D~splaccment- full load 57 tons 58 tons Maximum speed Move than 40 knots More than 40 knots Foil configurat~on Conventional Canard Fo~lborne Rolls-Royce Brlstol S~ddeley propulsion Tyne Proteus Licensed by Supramar A.G. Zug- Supel cavltatlng Water Jet pi opeller Hullbol ne Two General Motors One General Motors The propuls~on diesels (320 bhp) dlesel(l60 bhp) Greatest Experience On completion these craft will commence evaluation trials and in ~t is expected that one of the two will be chosen as a possible production unit for the US Navy. Hydrofoil Boat

Ultimate Size Studles indicate that hydrofoil ships with displacements between 500 and 3,000 tons are feasible. These studies assume that a ciegree of engineering effort is put into large designs which is comparable to that given to larger trans- aircraft. Frg 9 shows an rnstallation of a Marlne Olympus 22,300 hp englne whrch would be sultable for such large RODRIQUEZ h ydrofolls Hydrofoil Boats Across The Olympus is one of the world's most powerful turbo- jets. It has established a first-class reputation for relrabilrty The World's Seas since ~tsrntroductron to the RAF in 1956, and rs the engine chosen for the Concorde. A in 21 Countries In the marine verslon changes have been made rn materral to guard agalnst salt corrosion, and the fuel system and controls have been adapted for operation on d~eselfuel. It can be used as a boost englne In conjunction wlth tradl- tional rnachlnery or as the sole means of propulsion. The Marrne Olympus has been ordered for trials in the converted Br~trshfrlgate HMS Exn~outh It 1s also desrg- nated powerplant for the Royal Navy's new Type 82 destroyer The Frnnrsh Navy has also ordered the Marrne Olympus and the Germans have had an engrne on teqt srnce 1964 The Marrne Olympus has also been ordered by the Malaysian and Iranran navles It 1s a strarght-flow hrgh-pressure-ratro unit wrth a five- stage low-pressure compressor, and a seven-stage hrgh- pressure compressor each drlven rndependently by rts own single-stage turbrne through coaxral shafts. The compressors are niechan~cally ~ndependentand each runs at rts own optimum efficiency, grvrng the engine exceptronal flexib~llty and rapid acceleratron The specific fuel consumpt~on 1s low and full power is avarlable wrth~ntwo mlnutes of a cold start under any cl~maticcondrtloas. l'be development and b~nldingcosts of hydrofoil craft are high compared to those of conventional craft. There are many interestrng detail problems to be solved rn con- nectron with the hydrofoil whrch offer an extremely fasci- nating field for both engrneer and shlpburlder, wrth a mrnd for hlgh speeds and unconventronal desrgn

With crckno+vlcdgrnent to "Bristol Siddeley lor~rnol" ANY KIND of SHIP REPAIRS One air set, ductiizg and t~nk.The tow rope connecting the ussemhly can be seen. Other ropes support the extremely flexible ducting. The men provide scale

NG DAY

by R. A. Cole

An application of the air cushion principle makes light work of moving two 300,OQO- gallon storage tanks

OVING day always presents problems and thls is (9.14 m) and weigh well over 50 tons. M particularly so when the items to be moved are They were moved quite quicltly and easily by application either bulky or delicate. The Esso organisation were pre- of the hover cushion principle and at a lot leqs cost than if sented with qulte a problem recently when it was decided convent~onalmethods had been applled. This waq the first to re-arrange their storage site at Mode Wheel Terminal, time that such an operation had been carr~edout on a Manchester. commercial basis. For reasons of efficiency in site management the new Without this unlque method the removal of these tanks plan required that two 300,000 gallon (1,363,790 litres) would have posed problems and difficulties that could have storage tanks were re-positioned some 350 yards (320 m) bcen ~urmountedonly at a high cost. Tn fact ~t may well away from their existing position. This short journey in- have been that the cheaper proposition would have been to volved crossing rough ground with a slightly increasing scrap them and build two new ones. A major difficulty that level, a road, two railway tracks and then another stretch arose when considering conventional methods of removal of rough ground. At the same time it was necessary for lay in the fact that the water table was just a few inches the tanks to be orientated through 180 degrees. The size beneath the ground surface. This would have meant that of the operation may be judged from the fact that the special preparations for the use of jaclts and rollers or tanks have a diameter of 50 ft (15.24 m), a height of 30 ft bogies. The tank and one air set. Two light pel ible ducts deliver air to the skirt. Aiz unused duct entry can be seen orz the skirt

Methods and Details Air for the operation is supplied by centrifugal fans of To use the arr cushron method one first of all has to a type that are widely used for industrral purposes and these convert the storage tank to a rudrmentary hovercraft Thrs are powered by diesel engines. In this case two fans were 1s done slmply and effect~velyby clamp~ngtwo steel bands employed and each delivered 26,000 cubic feet of air per around the tank near rts base. Separated vert~callyby a mlnute (736 cubic metreslminute) at a pressure of few feet the bands carry attachment points for the seg- 60 lb/sq ft (293 kglsqm). Each being powered by a Ford mented sli~rtwh~ch 1s of nylon rernforced neoprene A few diesel engine of 130 bhp and mounted on a rubber tyred of the segments carry an entry facrlrty wh~chaccepts light trader which was hitched to the tank by a wi:: rope. Thus flexlble ductlng through wh~chthe alr 1s fed. The sketch as the tank moved the two air sets were automatically dragram shows the basrc form of the Inflated skrrt and towed behind it. The pull was provided by a w~nchmounted the fixing details. on the back of a lorry.

Iletcril of segmented sicirt. The photograph tciken during the moving sequence shorvs absence of du~tlargely due o water dampenirag. The skirt is cros~inga17 open gulley which hcr~been filled with baulks of timber crnd covered by tarpaulin Sketch diugrcrm slzows inflated form of segrneizted ~kirt (1s well ns the lnethod of uttochment to tank. Ground clecirarzce is measured from the underside of the tank

DETAIL OF 1

Amongst the list of prelimtnaries for this type ot opera- by the National Research Development Corporatron tion one finds the necessrty to cover open culverts and through ~tssubsidiary, Hovercraft Development Ltd. An drains so that air from the cushron cannot escape down inltial and completely successful trral was carried out using them. This rs readily achreved by layrng tarpaulins over a much smaller tank at a milrtary establrshment. General them. In the case of gulleys they must be filled wrth baulks contractors for thrs rnltial exper~mentwere Pynford Ltd., of timber prror to coverlng so as to grve a fairly even load a concern whrch specralrses rn jacking-up and movlng awk- bearing surface. For everyone's comfort a fire hose to ward loads and in the art of underprnnrng . tiampen down dry earth and surfaces and so prevent a dust As a result of their efforts and the experrence they have storm, comes as a final requirement. garned they have been granted a licence by HDL which Because these tanks had been in position for many years allows them to apply the hovercraft prrnclple to this type and had sunk several inches rnto the ground they were of work 'The Esso job was their first commerc~alunder- rather reluctant to lift. They eventually moved after about taking in this field and obviously it is not golng to be their half an hour of blowing and this part of the operation may last. We understand that they are currently negotlat~ngthe be likened to an initial prising-off job. After this they lifted removal of several other tanks by thrs method. very quickly once the air was being pumped and as much Reporting as rndependent observers of part of the as 10 inches (25 cm) of clearance could be obtained. moving operation we can say that it is hard to imagine Backgsoul~d how such an awkward itern could have been traversed This application of the hovercraft principle was devised more quickly, cleanly or efficiently.

The tank being winched forwcird from tlze back of a (.ry. Dust has been suppressed by watering the ground rovemen orne Navi A Report on Foil Systems Fitted up by the ding Company "Sea ight" of Messina

Giuseppe Giuffrida Technical Manager, Seaflight

OILUORNE navigation can be split into two basic systems : that no electron~cmeans of control or complicated mech- F The system of partly submerged foils or surface-piercing anlsms are necessary In order to resolve the problems of foils; the system of totally submerged foils. in-fl~ghtstability. But while the system is up to require- ments In a perfectly smooth seaway, its results are qu~te In princ~ple the main advantages and disadvantages different In a rough seaway. regard~ngeach system have been indicated as follows In fact, owlng to the orbital motions of the waves acting The surface-p~ercingfoll 5ystem has its major advantage over the submerged surface of the foils and ch~eflyIn con- in that ~t automatically ensure\ the three required equi- sequence of the waves, there is a continuous variation of l~briums;that is to say altitude (clearance) equilibrium or the lift, which causes audden motions of the craft: more stability, lateral equilibrium or stability, and longitudinal accentuated in the direction of roll. but less dangerous and equil~briumor stabil~ty less accentuated in the d~rection~f pitching, but more The word "automatically" has been used just to mean dangerous, in as much as any variation In the longitudinal trim when the craft is golng head downwards entails an a single equilibrium, but three equilibriums at the same equal var~ation of decrease In the fo~ls'~ncidence (since time: lateral, longitudinal and altitude. they are fixed to the hull) and consequently a loss of lift The sufefy of navigation (taking for granted a perfect even total or d~rectlyan increase of heaviness wlth a loss operation of the electronic brains governing the craft's of clearance and violent clashlng agalnst the sea. flight) relies on the perfect efficiency of all the electric The totally-submerged foll system presents the advantage circuits and the hydraulic installation; for any average of d~sengagrngthe foils' surface from the water-level and whatsoever will be detrimental to the possibility of navi- conseq~~entlyfrom the waves, yet remaining subject to the gating on foils. orbital motions of the waves, w~thcorrespond~ng varlat~ons This is a very important factor, especially in the case of the llft Conversely th~ssystem presents the great dis- of military employment. advantage of not having - in ~tsconception - elther alti- From a hydrodynamic viewpoint, it must be also ob- tude stabil~tyor lateral or long~tudinslstability served that a flap not aligned with its foil reduces the In order to make up for this serious gap, ~t is necessary hydrodynamic efficiency of the foil itself. that the lift produced by the submerged foils may be varied The Shipbuilding Company "Seaflight" have introduced of late into practical application some new foil systems both 111 the lateral and loilgitudinal directions by means of movable flaps and an electronic flight-control system. "with pre-set constant lift and self-adjustable incidence". Such foil systems belong to the surface-piercing foil Sonars, pendulums or gyroscopes and accelerometers are system and have the following features: the sensors of the electronic flight-control station; a They are not rigidly connected with the hull but with hydraulic station and a serles of valves of the hydraulic an axle, supported by bearings, transversal to the network electromagnetically dr~venand a certain number hull. of hydraulic cyl~ndersare the servo-mechanisms of the electronic flight-control station. Consequently the whole foil system can make rotary oscillations around the said axle. There IS no doubt that when nav~gat~ngin a calm seaway The effect due to the rotation is a variation in the the task of the electronic fl~ght-controlstatlon 1s enor- angle of attack by which the foil surface meets the mously fac~litated and the results wlll be very good, water flow. whereas the problem of counterbalanc~ng-in a perfect The foil surface develops for the most part slightly manner ancl wrlh the necessary promptness - the causes abaft of the axle of rotation and the lift produced by of perturbation due to the wavy mot~ons(of the seaway) it tends to rotate the foil backwards. 1s more difficult Similarly also the resistance to its advance tends to Wlth regard to that, one can observe : rotate the foil backwards. The sonars used for stabrlis~ngthe hull's clearance, I£ The movement of backward rotation is opposed by placed forward, are the only sens~tiveorgans to per- the force from a spring, or any other device, acting at ceive ahead of tlme (a small fraction of J. second) the the extremity of a lever, inside the hull, and united causes of perturbat~on with the axle of the foil system. All the other sens~tive organs intervene w~thsome The system is in equilibrium when the active moments delay after a removal from the posit~onof equ~l~brium of the lift and of the resistance to advance equal in value has become evident the reactive moment of the spring. Another delay 1s due to the flow of the Auld in the Some of the causes of perturbation of the equilibrium hydraulic clrcuit In order to obta~nthe required varla- and of its re-establishment, automatically, in a chrono- tions In the angle of the foil flaps logical succession of fractions of a second, are indicated It 1s not suficrent that the removal from the posltron as follows: of equlllbr~um alone be taken into account, but rt should be necessary that the accelerat~onat wh~chsuch When Crossing a Wave-crest an alteration takes place be taken into account too; and if such a movement cons~stsin a removal from, or Larger forl-surface submerged, greater l~ftproduced, a nearing to, the posit~onof equrl~br~um Increase of the active moment of the 11ft. 011 an average, one wave crest and cavlty wlll be met The major value of the actlve moment as compared durrng each ~econdof t~me,that is to say two var~atrons with the reactlve moment of the spring determines the per second, to whlch two openings of valves should corre- beginning of a rotatlon of the fo~lbaclcwards and a spond for each second - and 7,200 openlngs of valves per gradual redkctlon of the angle of attack. hour The excess of the lift produced by the wave-crest 1s From the frequence of the movements one can real~sethe thereby progressively annulled and the rotatlon of the huge wear on the mater~als,valves, hydraulic cyl~nders,and foil will end as soon as the equ~libr~umis re-established the~rcorrespond~ng packlngs Moreover, one must bear in between the two moments -active, and reactive. xn~ndthat some mater~alrsubject to rapld wear and tear Everyth~ngtakes In a fraction of a second and the rota- are placed in inaccessible places, and therefore the craft tion of the fo~lsystem, naturally accord~ngto the height will have to be la~dup for their substitution. of the waves under cons~deration,hardly reaches 1 degree. The l~ftproduced by the foll remalns practically constant The promptness of intervening through a variation in the wh~lenegot~atlng a wave-crest. incidence of foil-flaps is of a fundamental importance, but it is just as much important that the correct angle be obtained for an exact quantity of time. When Crossing a Wave-cavity The diflerent factors taking part In the problem are too This case is like the previous one, but with contrary many to be taken into proper account ind~vidually. effects and movements. Since the problem of obtaining with necessary prompt- ness a certain variation in the flap incidence in order to When the Craft's Bow goes Downwards balance a certain cause of perturbation of a certain equi- That may happen when negotiating - from the crest librium is already a difficult one, it is more difficult to towards the cavity - very long oceanic waves or sea about harrnonise the movements of the foil-flaps to control not to become a swell. A certaln angle of bow-lower~ngdetermines, in the craft (d) Usual helical springs with a constant pitch can be used w~thfoils rrg~dlyfastened to the hull, a reductron of the or incidentally with a variable pitch, having a com- angle of attack of the hydrofoil, havlng the same value; pressive force (stress) per mm of excursion equal to and a loss of lrft about 0.4% of the load weighing on the hydrofoil, W~ththe Seaflight's fo11 systems, the follow~ngwlll have capable of reaching maximum values of compression place chronolog~cally equal to 15 + 25% of the load weighing on the foil. Reduct~on of the ~ncidence,lesser llft, lesser actlve (e) During the take-off, owing to an expansion of the moment of the llft spring, the foil assumes its maximum incidence, limited The reactlve moment of the sprlng exceeds the actlve by a fit buffer-stopper, to which an angle of attack moment and a rotatlon of the foil begrns forward, must correspond ensuring the highest lift resistance thus gradually reinstating the angle of attack necessary ratio in relation to take-off speed. In such a way, take- in relat~onto the water flow. off becomes easier and will take a shorter time. As The rotatlon ends when the equ~llbr~umIS re~nstated gradually as the hull is lifted and its speed increases, between the actlve and react~vemoments and there- the foil reduces automatically its incidence. fore as soon as the ~nrtial11ft has been reinstated (f) The continuous equalisation of the foil, in terms of incidence, to the instantaneous conditions and the When the Craft's Stern goes Downwards continuous production of a lift almost constant do This case is like the previous one, but with contrary reduce vertical accelerations and consequently they effects and movements. reduce stresses both on the foils and the 11~111. (g) In very big buildings it is possible to reduce - when When the Speed increases having equal values of the stresses -the weight of the hull by having it supported not on two points (after The resistance to the advance of the foil system in- foil and fore-foil), but on a third point or more points, creases, thus Increasing the resistance active moment. with as many foils or couples of foils (starboard and The greater value of the active moment as compared port-side) oscillating automatically ; with the certainty wlth the reactive moment gives way to the beginning that the supports of the central hydrofoils will absorb of a rotation of the foil backwards and gradually, a certain share of deadweight independently from the through the further compression of the spring, to an waves and direction of the stream lines. Increase of the force exerted by the spring and an While the fore-foil will remain a surface-piercing increase of the reactive moment until the equilibrium type, in order to ensure lateral and altitude stability, is reinstated with the active moment. the intermediate hydrofoil might be a totally- During the rotation, a reduction of the angle of attack submerged type, also this oscillating rotarily, as it is takes place, which is necessary, in consideration of the required that it should bear only a share of the dead- speed increase, In order to keep the specific lift un- weight and should automatically equalise its angle of altered and consequently also the in-flight clearance. attack with the direction of the water flow which- as it is known - can be considered horiz,ontal only When the Speed Decreases with regard to the fore-foil ; and it is deviated by it This case is like the previous one, but with contrary (ie the fore-foil) in a different manner, according to effects and movements. speed, backwards. Until now we have examined schematically the advant- The problem can be solved easily by adopting oscil- ages and disadvantages of the foil systems, both the lating hydrofoils while with the foils stiffly fastened surface-piercing and the totally submerged ones, but rigidly to the hull one cannot obtain a constant and well fastened to the hull, and the undiscussed advantages repre- determined lift, but a variable one in relation to the sented by the Seaflight's rotarily oscillating hydrofoil, speed and the angle of the water flow. which contributes positively in the progress of foilborne navigation, especially with reference to its extreme simpli- Conclusion city and thereby its extreme safety of operation. The comparrson between the two basic systems of foils, For a more detailed examination of the problem, the whrch made one prefer the former or the latter ~n conse- following additional specifications are herewith supplied: quence of the cons~deration glven to the s~mplic~tyand (a) 'The oscillating fore-hydrofoil is divided into two single safety of the surface-prercing system (yet w~th the independent complexes : one on starboard and one on Inconveniences of the sudden movements of roll, wlth the port-side, thus eliminating almost totally the move- limltatlon of navigat~ngwith stern-sea not over a certain ments due to roll. wave-he~ghtand wlth the remarkable stresses derlv~ngfrom (b) The hydrofoil surface develops in such a way that the sudden falls ahead), or to the totally-submerged fo11 system centre of lift of the submerged part gets away from (freed from the perturbations of the surface of the seaway, the vertical plane passing through the axle of rotation but still a slave to an electronic bra~nand to the electric- (lever of the lift) as gradually as the foil emerges and magnetic-hydraulic servo-mechan~sms,wlth the unknown vice versa. poss~bil~tyof a perfect operation in a variously perturbed Such a feature is very important in as much as it seaway, both as regards its technical respondence and as reduces the variations of the lever (arm) of the lift by regards ~tssafety of operatrve durat~on)now appears to be effect of the rotation of the foil and the variation in decidedly In favour of the system w~thpartly-emerged forls the submerged surface of the foil. as two movements due to the contribution of the new foil complexes adopted in opposite direction are determined by the centre of by the Seaflight, hav~ng"pre-set constant llft and self- lift. adjustable ~ncidence", whrch add a further automation to (c) The reacting springs have such features as to deter- the system and el~minatethose defects Inherent to the mined variations of the reactive moment slight superior surface-p~erclngfoil system, w~ththe folk stlffly fastened -- in absolute value - to the variations of the active to the hull, also emphas~sing11s srmplic~tyin ensurlng a moment, with reference to a determined oscillation of solutlon of the varlous problems of equrllbrlum and opera- the foll. tive safety - hav~nga bas~cvalue for those who go by sea Captain Jacques Robitaille of Quebec, the first Canadian to qualify as a commercial Itovercraft opcrrrtor, is sllown above (right) reviewing Expo 67 hovercraft charter route maps with Captain I Peter Ayler of Ryde, Isle of Wight CANADA Hovercraft's Internationa Shop Window by G. Ray Gibson ONTREAL'S one thousand acre Expo 67, if measured M in terms of area, of National participation, of interest and entertainment for the individual visitor, stands out as the largest and finest event of its kind to date. Indeed there has never been an exhibit~onsuch as Expo 67. The Canadian Federal Government, the City of Montreal and the Province of Quebec have co-operated magnificently to make possible not just the event of the year but the wonder of the century. Cons~derthe one thousand acre exhibition site which is lald out in four main areas. The first area was the former Mackay Pier breakwater which had over four million tons of new land added. Second 1s the upstream end of the original Ile Sainte HClkne (named by the French explorer Jacques Cartier in 1535 after his wife HitlBne). 'Third is a new island, Ele Notre-Dame, bordering on the Seaway and fouith the downstream extension of Ile Sainte HBlBne known as La Ronde. In all some 30 million tons of earth and equipment, more weight than all the Egyptian pyramids, were moved to create the overall site. Most world fairs of International standing have at least seven years to build their site on solid ground. The Canadian planners of this exhibit had less than four years to get their show on the road and on an area partly beside and partly beneath the St. Lawrence river. This The hovercraft ofice at Citi du Havre i5 onc of tlzree sucl~ extravaganza is the only "first-category" exposition ever portable buildings of modern design ~,hichserves a dual pur- to be held on the North American Continent. It meets the pose as radio control centre for tlze ilCVs NIZ~passenger ticket rigid standards of timing, scope and operation as estab- ofice lished by the world today regulating such international exhibitions. At London's Crystal Palace Exhibition in 1851 the pany Andrew German Ltd. Ultrmate control of vehicles world first accepted iron and glass architecture. At the and the~roperat~on remalns wlth the more experleiiced Exhibition in 1904 structural steel and steam engin- Brltish Hovertravel management Anthony German, vlce- eering made their debut. Today at Expo 67 advanced pres~dentand general managcr, Hoverwork Canada Ltd, forms of transportation will no doubt be one of the major controls the servlce from an operatlonal headquarters at points by which this exposition will be remembered. Space the La Ronde slte, and from adrnln~stratlon ofices at craft, hydrofoil ships and hovercraft are on show to the Place Vllla Marle In downtown Montreal. I vls~tedwrth greatest international audience ever to assemble at any Mr German early In July to revlew his companys opera- time. From April 28th, when the show first opened, until t~onand to report back to the readers of thls publ~cat~on. October 27th, some 70 nations will exhibit to visitors from I was very much ~mpressed,not just w~ththe efficiency around the world. These visitors will have the opportunity and fr~endlymanner In wh~chthe company was operat~ng, of travelling to the Expo 67 site in British built hover- but with the factual stat~st~cson the operatlonal success craft operated by Hoverwork Canada Ltd. of the servlce Expo Hoverservice Canada's first commercial hovercraft operation is now in full swing carrying visitors to the exposition. Two radar equrpped 35 passenger, 50 miles per hour SR.N6 amphib~ouscraft are running regular transportation ser- vices between specially constructed terminals at La Ronde and the parking lot on Ile Charron, and along the river between La Ronde and Citi: du Havre. A th~rdroute carries passengers on a thrilling sight-see~ngtrip around Ile Sainte Hi.lkne over the fast running waters and rapids and under the bridges of the St Lawrence. Special charter trips are also available for private groups. These hover- craft trlps of the Expo 67 islands is probably the most convenient and spectacular way of viewing the overall exhibition. Trips between Citi! du Havre and La Ronde run every hour on the hour from 1100 hours in the morn- ing until dusk. The Ile Charron-Expo service runs from 0915 hours to 2100 hours. The sight-seeing trips start at 1130 hours and run continuously until 2030 hours. Roverwork Canada Ltd, the company that operate these craft, is very positive and agressive in their efforts to make hovercraft work out on this side of the Atlantic. The With the Russian pavilion on the Ile Notre Dame and Con- company is owned on an approximate 50-50 basis by the cordia Bridge as a background, a IzXovercraft negotiates the British company Hovertravel Ltd and a Canadian com- ,St Lawrence River in a strong cross wind To meet Port of Montreal reg~llutions for water craft, all On lift-off the craft Poats down the rainy on lo the river clear are req,Lir.ed lo curry gr.uppli,lg of the special loc~dingplutform above on eitlzel. sicle of the forward hatch

On the day I v~sltedthe Expo, Wednesday, July Sth, It would be impossible to l~stall the famous people who some 130,000 passengers had been carr~edfrom the tlme have used the Expo Hoverservice. For example, Britain's of the falr's openlng In Apr~l.I enqulred of Mr German Princess Alexandra and her husband Angus Ogilvie used what the~rbuslest slngle day had been. Thls was Monday, the service while visiting the exposition in June. My June 26th when some 4,356 passengers travelled on the Christopher Cockerell, British inventor of the hovercraft, craft An all up record for hovercraft operation anywhere and Monsieur Bertin, the French ACV inventor, were also In the world. Down tlme durlng the over 1,000 hours' among the early vis~tors. The American stateswoman, servlce fly~nghas been less than 1%, a remarkable ach~eve- Clair Booth Luce, chartered a craft on two separate ment Sklrt repalrs to date have been mlnor wlth s~ngle occasions for entertaining friends. Dr J. Herbert Holler- panel sect~onreplacement as the maximum problem en- man, US Under Secretary of Commerce, had the craft countered Th~sexcellent servlce record can be attributed demonstrated for him. Of noted Canadians, Mrs Pearson, to planned n~ghtmaintenance operatlons, by a ground wife of the Prime Minister, and Mr Phill~peGayliardi, englneerlng staff of SIX englne and a~rframeoperators and Minister of Highways for British Columbia, were early two sk~rtrepalr mechan~cs. Head~ngup the englneerlng users. lndeed Mr German's list of noted visitors reads operatlons team IS Mr R~chardStratton, chlef englneer of somewhat like a very special copy of Who's Who. Hoverwork Ltd, one of the most exper~encedmen In the If the international transport Industries have, in the past, hovercraft operatlons field. held any reservations about the reliability of such craft, Hoverwork's senlor captaln, Peter Ayles, of Ryde, Isle Hoverwork Canada Ltd has now removed all possible of W~ght,heads up a fl~ghtcrew of five p~lots.CBptaln doubts by demonstrating these craft under maximum Jacques Rob~ta~lleand Bert Mead are Canad~ans,wh~le operating conditions. As stated by Mr German during my Capta~nsArthur Phlll~psand Ben Goldsmith are Br~t~sh, recent visit "Expo provides a spectacular shop window for mak~ng up the very busy group runnlng th~s7-day a hovercraft. The public is already showing a tremendous week service The logrst~csof such an operation calls for interest in the vehicles and are using them to commute some 16 beach staff to handle passengers and control ser- across to the Expo site rather than for pleasure trips. We vices. All beach staff were tra~nedon the job pr~orto the believe this to be just the beginning of our company's openlng of Expo and are In the most Unlvers~tystudents commercial operations. Canada has plenty of tough trans- on summer vacatlon from Canad~anUn~vers~tles. A pre- portation problems which require solving, Hoverwork is employment requlslte for all beach personnel IS a know- ready with two excellent craft to go to work on these ledge of both Canad~anlanguages, French and Engl~sh. problems." Mr German also polnted out that BP Canada MISS Kathleen Foley, on leave from post-graduate work Ltd was a co-sponsor of the service. BP have collaborated at Montreal's McG~llUnlverslty, was selected as Hostess closely in the operat~onaland commercial development of and works dlrectly wlth Mr David Seatle, Hoverwork the hovercraft and have played an important role in most Canada's traflic manager, In keep~ngthe operat~onrunnlng of the hovercraft "firsts" in the United Kingdom, Europe, to schedule Africa and North America. BP Canada are also at this PEOPLE AND PROJECTS continued from page 7 The Navy's newest Hydrofoil gunboat and the nation's latest research submarme will make West Palm Beach, Fla, their test port under the terms of an agreement concluded by Grumman Aircraft Engineering Corporation of Beth- page, NY, and the Port of Palm Beach. According to Willlam T. Schwendler, Chairman of the Executive Committee at Grumman, the Florida port will be the test and operational base for both the Grumman- Piccard submersible PX-15, now being constructed in Switzerland, and the hydrofoil gunboat "Flagstaff", being built by Grumman at Stuart, Florida. Present plans call for the Flagstag to be launched on or about November 15th and to be berthed at the Port of Palm Beach two or three weeks later. Schwendler said that West Palm Beach was chosen after detailed surveys of several other East Coast . The Gruniman support facilities at Stuart, the nearness to deep ocean waters, and specified technical mechanical capa- bilities at West Palm Beach led to a determination in favour of that location, Schwendler asserted. Under the terms of the agreement, Grumman will occupy some 9,600 sq ft of a building to be erected in Riviera Beach, at the intersection of Route 1 and South Road. An additional slir, measuring 50 ft bv 150 ft will be A group of typical Expo 67 visitors loading on board for tlze reserved for the ~ruhmanhy&ofoil and submarine trip out to Ile Sainte Hhldne. Their baggclge, ir~cl~ldirlgpicnic vehicles, as well as dockside storage areas totalling some baskets, prams, etc, always manages to be .stored on board 9,450 sq ft. The lease arrangements continue for one year with options available to Grumman. For the PX-15, the base will mark the port of departure for its proposed 1,500-mile submerged journey in the Gulf time ~~ndertakingall the fuellrng and lubricatrng arrange- Stream, from Florida to Nova Scotia. The 50-ft, 130-ton ment~for the Expo 67 hovercraft servrce. submarine will drift silently at depths of 300-2,000 ft, with After meeting Mr German and his very talented its crew of six performing visual and instrumental measure- associates I am sure that hovercraft transportation is here ments of deep ocean phenomena during the six-week in Canada to stay. Providing this young company is given journey which is scheduled for the summer of 1968. Dr proper support and an opportunity to show what they can Jacques Piccard, who provided the basic design of the do on a commercial basis there is no reason, in the view PX-15 and is supervising its construction, will lead the Gulf of thrs writer, why they should not be successful on the Stream Drift Mission. long term baas. In December of this year, West Palm Beach will become the base of the Flaprtaff for the rieorous sea trials that - u ,d ., must be completed prior to formal acceptance by the US Navy. The 75-ft, 60-ton, turbine-powered vessel is expected to reach foilborne speeds in excess of 40 knots in heavy seas. The Flagstag will be turned over Lo the Navy in early 1968.

The Council of the Institute of Marine Engineers has decided that a Sectron of the Institute for the d~scuss~onof miscellaneous craft and ocean englneerlng shall be formed. The rnterests of the new sectlon will lnclude fishsng vessels and their mechanical equipment, hydrofoils and hovercraft, small ferrres, lifeboats and slmllar craft of thrs order of size: ocean engineering wrll rnclude the mechanlcal and structural aspects of offahore drillrng equipment, the mech- anrcal aspects of laying plpel~nesunder the ocean, manned and unmanned craft for underwater experrments, welding and simllar processes underwater, methods of locating objects under water, and mechanlcal and electrical engineering aspects of any future developments rn ocean engineering It IS the Intention that from t~meto tsme special meetlngs for the discussion of these aubjects shall be arranged and a Sub-Commsttee has already been formed with this Intention Wlzilc approaching the Cite du Havre at speed, a hovercraft -k * prepcrres to arrest on the special meiul-fcrced ramp developed * r by Ifover~vorkCarzada Ltd for far: Po~lingoper.cltions (Corztinued orz pc~ge 30) Hydrofoil Boats or Hovercra

An extract from the 1965 Annual Report of the Norwegian Institute of Transport Economics

BGULAR hydrofoil boat services have been run in lifted off the water during operation, the propulsion resis- R Norway since summer 1960. The Stavanger and tance is much less than in the case of ordinary boats. Sandnes Steamship Companies at that time acquired a Other common features of the two types of craft are that Supramar PT-50 hydrofoil boat which was put into service their mode of construction and their machinery is rather between Stavanger and Bergen. One year later the com- different from the equipment normally available to ship- pany acquired another PT-50 which was also run on this ping companies. Also, a more comprehensive maintenance route. Sometime later the Stavanger Steamship Company and special knowledge is required than for ordinary commissioned a smaller hydrofoil boat, the Supramar vessels. As opposed to hydrofoil boats, the majority of PT-20, to cover a route between Stavanger and various hovercraft are independent of water depths and can also centres in the Ryfylke Fjords. The same type of boat is over land. However, hovercraft must primarily be used by the Hardanger-Sunnhordlandske Steamship Com- considered as being means of sea transport. pany on a route between Bergen and Sunnhordland. These Any choice of "high speed vessels" will in most cases services are normally operated from MarchIApril to the be between hydrofoil boats and hovercraft. Even though end of November. the two types of vessel may have roughly the same per- In Oslo Fjord a hydrofoil service was started in 1964 formance, one type may possibly have obvious advantages with two boats of the PT-20 type. This service was of an operational or economic nature. operated throughout the year and has recently been granted Of the existing hydrofoil boats the greatest chance of a provisional permit for operating in the dark. Thus, six success lies with models Supramar PT-50 or PT-20. Other hydrofoil boats are now being operated in Norway. available types are less suitable or too expensive. The Westermoen Hydrofoil AIS, Mandal, are producing hydro- example glven below has been drawn up with a view to foil boats for the Scandinavsan market. Altogether approxi- servsclng a possible route at Meire and Romsdal is based mately 80 hydrofoil boats of different Supramar types on Model PT-20 with accommodation for approximately are now In operation throughout the world. 70 passengers. In this area the PT-50 (100 passengers) will Operational expersence wlth hovercraft in Norwegian probably be too large. waters is based on the use of two Westland SR-N6 hover- At present only the Westland hovercraft SR.N5 and craft at More and Romsdal in summer 1965. This service SR.N6 appear to have any commercial value. Because of was operated from June 28th to September 25th. In the its larger passenger capacity model SR.N6 appears to be course of this period the two vehicles were in operation the most sustable craft for passenger traffic, the extra for a total of approximately 1,150 hours. From October operational and initial cost as compared with model SR.N5 1965 to February 1966 these vehicles were put into service being much lower than the difference in passenger capacity between Aarhus and ICalundborg in Denmark where, at (37 as against 17 seats). It would appear that during the times, they were tried out under very dificult operating service in summer 1965 the available accommodation on conditions. At present approximately 25 Westland SR.N5/6 model SR.N6 was most suitable for the route in,question. hovercraft are in service. Services are operated in the UK, SR.N6 has a cruising speed of approximately 50 knots USA and . Another hovercraft is in service in Brunei as compared with 34 knots for PT-20. However, the work- and the British forces in Borneo have operated two hover- ing capacity for IT-20 will be 301% higher than for SR.N6 craft for approximately one year. because of the greater passenger capacity. The hydrofoil Both hydrofoil boats and hovercraft have the advantage boat passenger cabin is relatively larger, measuring that they are considerably faster than ordsnary boats. approximately 0.7m2 per passenger as compared with In view of the fact that the hulls of these vehicles are 0.5 m2 on the SR.N6. Travelling Time ie, with wave lengths from 314 to 1.5 times the length of In coastal districts the use of hydrofoll boats or hover- the craft, the speed must be reduced to approximately craft w~llgive considerably shorter travelllng tlmes than 42 knots. conventional shipplng routes. In most cases the tlme-savlng Even though there 1s no l~mltationon hydrofoll traffic, \ as compared to / and pure bus connection will 4 ft waves wlll so much reduce passenger comfort that, m also be cons~derable This, as a rule, 1s due to the fact practice, the servlce must be stopped Both types of craft that sea travel distances are shorter than road connectlons are, therefore, sultable for servlce only on narrow waters between correspondlag places In the coastal areas In the Hovercraft are, at present, not permitted to travel In wlnds event of the express boat connectlons berng qurte parallel exceeding 20 knots, le, w~ndforce 5. This indrcates that to the bus routes, the time-savlng wlll, In most cases, be the regularity mlght be lmpalred durlng winter operation inslgnlficant. Model SR N6 has a crulslng speed of approxl- Wlnd observations talten on Rundo from 1941-50 lndlcate mately 50 knots, but experlcnce gamed in regular servlce that the wlnd force 1s In excess of 5 for about 15% of operations lndlcates that, for practical purposes, the the perlod from October to May As Rundo 1s much more average speed 1s In the region of 40-45 knots. For hydro- exposed than the actual servlce route for high-speed boats, foil boats of the PT-20 type a crulslng spced of 32 knots lt is to be expected that the servlce can be operated some- is expected. Th1~mcans that the travell~ngtlme on high- what more regularly than the figures ~nd~cate.It should speed boats could be reduced by 50 to 70% as compared also be mentioned that AB Sundfart who operated the with parallel shlpplng routes. hydrofoll boat servlce over the Oresund w~thtwo PT-20 The travelllng tlmes on h~gh-speed boat servlces at and one PT-50 close down their service in w~ndforce5 More and Romsdal are cons~derably shorter than when and wave heights of 4ft, le, as In the case of hovercraft. travelling by bus and ferry Wlth hovercraft the travelllng Durlng the trial service wlth the SR.N6 at More in tlmes wlll be reduced by up to a quarter or one-thud over summer 1964, only five journeys were cancelled because "favourable" distances The travelllng trme by hydrofoil of bad weather from 2816 to 1219. The day before the boat wlll be from 35 to 45% of thc usual present-day service was opened, however, the craft was weatherbound. travelling time Even though the hovercraft is 20 to 30% Of almost 1,600 actual passengers only 4'% suffered faster than the hydrofo~l boat over most sectlons, thls delays in excess of ten minutes. Approximately one-third means relat~velyllttle In terms of shorter travelllng tlmes of these delays were due to bad weather. The hydrofoil on the shorter routes applicable to More and Romsdal. service between Stavanger and Bergen, which covers rela- On the major~tyof routes the tlme d~fference1s in the tively highly exposed sea sectlons over Roknfjorden and reglon of 10 to 15 mlnutes. Sletta, had to cancel only 5-6 passages per craft in 1964. The route which will give the most favourable result The PT-50 boats used on thrs service are, however, more for high-speed boats is between Molde and Vigra airport. seaworthy than the PT-20. The PT-20-express boat- However, the hydrofoil boat must land its passengers a operating over the Ryfylke Fjords during the same period greater distance from the airport than a hovercraft and, was cancelled for one day only. consequently, involves longer bus times. In the event of a future hovercraft service being planned, it is possible Operational Safety and Maintenance to avoid this additional changing by moving the vessel The number of technical irregularities wlll largely right up to the airport. This, however, requires considerable depend on the accuracy and programme of the main- planning work between the airport and the beach. If this tenance service. In order to avoid any unnecessary opera- can be put into practice, it will be possible to reduce the tional delays it has proved necessary to malntain a com- travelling time by approximately 5 minutes. prehenslve spare parts store. The hydrofoll boats have, among other thlngs, been troubled by propeller and pro- Regularity peller shaft d~ficulties.With preventative maintenance such A satisfactory regularity is a prerequisite for commercial as, for example, inspection or replacement of propellers operation. The users' confidence will suffer greatly if the after a certain number of operating hours it has been services are cancelled and delays occur, even if this hap- possible to reduce this problem. In addition to propeller pens to a limited extent only. Regularity will depend on cavitation, the propellers and foils can also be damaged the seaworthiness of the craft and their operational relia- by floating objects. bility. Particularly the latter may give rise to problems The main maintenance problems in connection with the when starting a new service with a new means of trans- hovercraft used at M0re were due to oil leakage as well port. Teething trouble must be expected, but the ability as damage to the sklrt and, particularly, the centre keel. to overcome such trouble is decisive for the future of the Trouble in the hydraulic system gave rise to approximately service. 25% of all passengers cancelled. There was also motor trouble, possibly due to contamination of the fuel when Wind and Weather tanking up from barrels. The other problems were of a As far as regular services are concerned, the sea- more incidental nature and normally negligible. Approxi- worthiness of PT-20 and SR.N6 will be roughly the same. mately two-thirds of all cancellations at M0re occurred It is possible to run a PT-20 with 4 ft waves without speed durrng the first 14 days of the service. At present the reduction and with approximately 6.5 ft waves with reduced hydrofoil boats appear to be able to ensure a better tech- speed. This, however, depends on favourable wave types nical regularity than hovercraft. This, however,, must be and directions. With waves from the rear, for example, the assumed to be a transition phenomenon. There is nothing seaworthiness will be reduced. SR.NG may be operated to indicate that hovercraft should not become equally with waves up to 4 ft high in Norway (5 ft abroad), but reliable as the hydrofoil boats. in the course of several experiments it has been found that Both types of craft require specially trained main- the craft can negotiate considerably higher waves. The tenance mechanics, but there is no reason why the craft can be driven at a speed of 50 ltnots in waves operating companies should not bekable to train their own approximately 3 ft high. Under unfavourable conditions, technical staff to carry out maintenance and daily inspec- Andalsnes-Molde Molde-Vigra a~rport 3 h 40 min Molde-Alesund Andalsnes-Alesund Alesund-Hareid Alesund-Gvsta 2 h 0 min

tions. Hovercraft engine overhauls, however, must be Norway are counting on a depreciation period of eight carried out In special workshops, but engine replacement years per craft, but experience seems to indicate that the can be carrled out within one day so that the craft does life of the craft is considerably longer. As it is to be not have to be kept out of operation for any length of expected that today's hovercraft will age relatively quickly time. The overhaul intervals for hovercraft are, at present, bccause of technical developments. they are depreciated very much shorter than for hydrofoil boats. In the course over a period of five years. of the short t~meduring which the craft have been in In addition to depreciation there is 6% interest on half operation, there has, however, been a considerable increase the investment amount, and insurance premiums. These in the overhaul intervals. In July 1965 the expected engine amount to approximately 2.5% of the initial price of the life was approximately 500 operating hours, but by October hydrofoil boats, whilst for hovercraft they must be assessed this was increased to 1,000 hours, and it is expected to at at least 4%. On this basis the annual capital expenditure extend the overhaul intervals to 2-3,000 hours. The pro- will be 350,000 for a PT-20 and 600,000 for an SIR N6. peller life has been increased from 250 to 1,000 hours. To this must be added depreciation and interest in respect On the other hand it has been found that the skirts and, of the spare parts store. in particular, the centre keel have suffered more wear than The capital expenditure will be approximately 75% expected. After approximately 800 operating hours the higher for hovercraft than for hydrofoil boats. This is skirts of the two models SR.N6 provided by Scanhover mainly due to the short depreciation period for SR.N6. were completely worn and had to be replaced. The centre keel had a very much shorter life, but better skirt material A PT-20 will normally requlre a crew of three, ie, cap- may be able to improve this. During the service period at tain, navigator and engineer. The service programme will M@re and Romsdal roughly two ma~ntenance working determine the total wage expenditure, but on most routes hours were required per operating hour. two-shift operation will be necessary. The hiring price is approximately the same for the two craft. The captain's Operating Costs pay will be in the region of 2,000 kroner per month plus In the following paragraphs only the pure operating subsistence money, where applicable, but including health costs w~llbe dealt with. In addition to these there are insurance and the lilce. In addition to the craft crew, administration, advertising, technical and other costs which mechanics will be required for maintenance purposes. vary from company to company. If an express boat service Naturally, this work can also be carried out at a workshop. is started by an existing transport company this will not In the case of SR.N6 at least three people are required for involve any major increases in the con~pany'sadministra- daily and periodical maintenance. Hydrofoil boats do not tion costs or overheads. On the other hand, when starting normally require daily inspection, and daily maintenance up an entirely new company, considerable investments are can be largely carried out by the engineers. On the whole, required in addition to the need for acquiring special tools however, expenditure on crew and mechanics will be in and technical equipment. approximately the same order for both types of craft. For A type PT-20 hydrofoil boat from Westermoen Hydro- the SR.N6 wages will amount to approximately 10% of foil A/S, Mandal, costs approximately 1.9m kroner. In the total operating costs, whilst the corresponding figure addition, a spare parts store has to be established at a cost for hydrofoil boats may amount to 20%. With ordinary of approximately 200,000 kroner. The size of the spare ships the charter price will be approximately 20-25% of parts store does not increase proportionally to the number the operating costs. of craft in service. Hovercraft can either be rented or The maintenance costs for a PT-20 hydrofoil boat will purchased. The price of one SR.N6 ex-works, England, is be distributed between hull and engine maintenance at a approximately 2.2m kroner. In addition to this, a spare ratio of approximately 50 : 50. Expenditure on propellers parts and special tools store must be maintained. The size and the like will depend on the number of operating hours. of this will vary. The works indicate approximately 90,000 With the amount of exploitation of these craft in Nor- kroner per craft, but experience has shown that this is not wegian waters the annual maintenance costs will be in the enough. region of 100-130,000 kroner. The number of operating In addition to the ordinary minor items, skirt sections hours has varied from 2,200 to approximately 3,000. If and various main components must be kept in store. This all maintenance costs are related to the number of oper- will involve a considerable increase in initial spare parts ating hours, this would indicate a maintenance expenditure costs. Apart from a spare parts store, approximately 20,000 of approximately 50 kr per hour. Major damage, for kroner's worth of special tools must be kept. Also it may example to engines, is covered by the insurance company, be necessary to have a crane for lifting the craft, but no but any non-refunded damage and franchise must be special crane is necessary if an ordinary 5-6 ton crane is included in the maintenance costs. available. Hovercraft maintenance costs are practically propor- The companies operating hydrofoil boat services in tional to the number of operating hours. As the main- The relatively high ticket prices for the hovercraft Table 2. Annual capital expenditure on PT-20 and SR.N6 excluding parts store (in 1,000 kroner) service in summer 1965 may have been a contributory PT-20 SR.N6 factor to the small amount of passengers. The average Depreciation period 8 years 5 years capacity utilisation was only about 15%. The accident with the SR.NS in April 1965 and the poor regularity during the Depreciation 24 3 440 first three weeks of operation, however, may have had a Interest 57 66 similar effect. Insurance Premiums 50 90 The additional cost involved in using a hydrofoil boat instead of the buslferry service will vary from 20-90'% with services in M0re and Romsdal. For hovercraft, however, the additional cost will amount to 70-158%. tenance intervals increase, a considerable reduction can be In view of the high ticket prices it is important to reduce expected. When entering into maintenance contracts with the travelling distances to a minimum as compared with manufacturers of englnes and boats ~t IS possible to pay a any buslferry services. Among the examples mentioned the certain amount per operating hour to cover the cost of Molde-Vigra a~rportservice is particularly distinctive. A general overhaul work, spare parts and, as far as the service parallel with a land connection, e.g. from Andalsnes engine manufacturers are concerned, also spare engines to Alesund, will hardly be able to compete from the price so that the craft does not have to be taken out of service point of view. while the engine is being overhauled. With today's over- In order to cover fuel and maintenance, the PT-20 hydro* haul intervals an amount of approximately 300 kr must be foil boat must carry at least six passengers per trip at the expected per operating hour to cover overhaul costs. In above ticket prices. The SR.N6, however, requires eleven addition, it may be necessary to replace certain parts passengers. A number of passengers above this figure will during the periodical 60, 120 and 600 hours maintenance contribute towards covering the fixed expenditure. or at other times. Tn the long run it may be expected, however, that maintenance costs will be further reduced. Conclusion The fuel consumption of a PT-20 is between 180 and The greatest advantage of "express boats" lies in the fact 200 litres diesel per hour. Also there will be a certain that they can offer shorter travelling times in the coastal consumption of lubricating oil so that a total cost per hour area than any conventional means of transport. Hovercraft for these two items of approximately 50 kroner may be have the highest speed, they are independent of sea depths expected. The gas turbine of the SR.N6 operates on and floating objects such as, for example, fishing nets. The paraffin, and the hourly consumption has been assessed at amount of time saved as compared with hydrofoil boats approximately 350 litres for maximum continuous opera- will not, however, be considerable over distances of up to tion. During the service at Merre the consumption per fifty nautical miles. Hydrofoil boat expenditure will be con- operating hour was 300 litres. Idle running accounted for siderably lower and might make it possible to establish approximately 10% of the operating time. For idle running profitable services with fewer passengers. 1 the consumption per hour is approximately 100 litres. In The possibilities of technical development are probably addition to the fuel, an allowance may have to be made greater in respect of hovercarft. It is to be expected that as for lubricating oil. The consumption during the MQre more experience is gained, the maintenance costs may be period was 0.6 litres per hour, but this consumption was able to be considerably reduced. A reduction to one-half of abnormally high because of several cases of oil leakage. the present maintenance costs within the next few years is The total fuel and lubricating oil consumption per hour feasible. It is also possible that simpler and more efficient during the M~reservlce amounted to 87 kr, but it is designs may appear. This would result in lower initial costs. expected that for idle running the cost per one hour's Larger craft will also be more economical. Hovercraft hav- opiration will be approximately 95 kroner. ing fixed side walls have resulted in a cost level similar to Variable costs will be approximately 100 kroner for the that of hydrofoil boats. On the other hand, these craft were PT-20, whilst for the SR.N6 they will amount to 400 unable to travel over land and thus depended on sea depths. kroner. In addition there may be booking fees payable to At present, this principle is being further developed to pro- travel bureaux, port dues, etc. vide certain amphibious characteristics, although not in the same order as with flexible skirts. It is to be expected that Table 3. Ticket prices with buslferry, hydrofoil and a development of these craft might result in very favourable hovercraft for certain services at MQre and Romsdal operating costs. Ticket Price (kr) Bus / Hydrofoil As regards hydrofoil boats, any further development of Service Fcrry Boat Hovercraft fully immersed foils may result in improved seaworthiness. Andalsnes-Molde 10.00 13.50 20.00 The craft now offered on a commercial basis having this Molde-Vigra airport 16.25 19.50" 27.00 foil system are, however, rather expensive to buy. They are Molde-Alesund 12.50 21 .00 31.00 also more complicated than the vessels offered, for example, A~idalsnes-Alesund 16.80 35.00 49.00 by Supramar. A considerable cost reduction for hydrofoil Alesund-Hareid 4.50 5.00 9.00 boats is, therefore, not to be expected. Alesund-rPrsta 11.40 14.50 23.00 In the long run the cost difference between hydrofoil Vncluding bus from Valder~yto Vigra airport boats and hovercraft will probably be reduced. Competi- tivity as compared with buslferry survices will depend on Ticket Prices the extent to which the relative costs of express boats can For the hovercraft service at Mgre and Romsdal in 1965 be reduced. the ticket price was 85-90 ore per nautical mile. For com- Express boat services are sure to play a more important parison, the prices for the hydrofoil services between part in the national transport system in years to come. In /Bergen and Stavanger were 60ore. Ticket prices will certain cases, for example, they may be looked upon as an depend not only on the direct costs but will frequently alternative to airport extensions b,y acting as a feeder have to be adapted to the market. service to existing . by Terence Ford C.Eng., AFWAeS

HAT the Government should take a greater financial The company commenced servlces across the Solenr In T Interest in the private hovercraft operator was one of 1965 and during the first year operated at a loss, which was the chief impressions retained after discussions with Hover- not entirely unexpected, and made a small profit during the travel Ltd, at Ryde, Isle of Wight. The company has next year. This was, however, due to the charter side of carried more passengers than all the other hovercraft the activities, the passenger service proving expensive to operators combined and, as the chairman said recently, ~t run. This year a loss is agaln expected and several reasons is the only organisation of this type with the discipline of have been advanced for this state of affairs and for present a Umited financial background. No subsidy is received from economic difficulties. official sources despite the fact that Hovertravel supplies One of the first to operate hovercraft commercially, techn~calinformation to Hovercraft Development Ltd, the Hovertravel had carried well over 600,000 passengers by ship division of the National Physical Laboratory and the July 1967, while the associated company Hoverwork Ltd British Hovercraft Corporation. 1s currently operating SR.N6s ferrying passengers across the St Lawrence river to Expo '67 at Montreal. Hoverwork sive, and it is this burden which has fallen heavily on to is well known for the training of hoverpilots and engineers the private operator, in particular Hovertravel. and lor operations in the charter field. Associated Companies Operatious and Ecol~omics Hoverwork Ltd has, together with Hovertravel, com- Dlfficult~es have been exper~encedby prlvate operators pleted more operatrng hours than any other organlsation. concerning the llm~tat~onsimposed by the size of the Thls assoc~atedcompany has bullt up a very useful record SR.N6, the t~melnvolved In the necessary maintenance as ~t has trained the major~tyof c1v11 hoverp~lotsand the work on thls craft, and the expense incurred. W~tha maxi- first members of the first m~litaryoperat~onal hovercraft mum of th~rty-e~ghtpassengers, ~t is not considered eco- squadron. Hoverwork was established to fill the gap be- nomlc by Hovertravel and other operators, but at the tlme tween the hovercraft manufacturers and the operator, and when servlces were ln~trated,11 was the only su~tableone it 1s the company's object to place at the d~sposal of available The ideal sue for the Southsea-Ryde servlce operators the extenslve experlence gamed by Hovertravel would seem to be a craft with about s~xtyseats or so, and m the operation of its servlces. the BH 7 comes into thls category but IS not expected to In the tralnlng of hovercraft captains, Hoverwork's become available for some years. Hovertravel are expect- course provldes for a progreyslon of role7 from rrdlng as Ing to take dellvery of an I-BM.2 rlgld s~dewallcraft In the supernumerary under lnstruct~on,through dual control to early part of next year, but this IS essent~allyfor deep command of the CC.5, used as an ab znitio tralner, then water operat~onsand does not fulfil the amphibious re- under instructiorl on the SR N6 leading to fir11 command quirements for the Solent route. The SR.N4 has been con- of that craft. Operat~onsare carried out under these condi- s~deredbut thls IS too large for such a servlce between the tions both in day-t~mecond~tions and at nlght wlth radar malnland and the Isle of Wight. Econom~cally v~able Elements ot the syllabus also Include engineering con- operations on thls route have become a necesslty, the slderat~ons,flexrble-sk~rt technology (particularly relevant hovercraft having attracted a cons~derableproportion of to operating speeds and econom~es),traffic management the passenger traffic. Hovertravel are now carryrng about and rescue and emergency procedures, Seamanship, with 100,000 passengers a month, w~thmore than 100 fl~ghtsa dlnghy sailing nav~gatronand the general ways of the sea day on the Solent schedules. Improvements are hoped for are also included as integral parts of the course. Hover- In the financial sphere so that these services may contlnue craft law and Insurance are covered and a full englne to be operated. course at the manufacturers 1s an essential part ot this Background to Hovertravel plot-tra~nlngscheme In 1964, Hovertravel's predecessor, Hovertransport Ltd, It can be seen that w~ththls comprehenslve syllabus, a had a successful summer season, and because of their graduate from Hoverwork's trainlng course 1s equlpped experiences, Hovertravel was formed In 1965. One SR.N6 w~ththe necessary knowledge, sklll and experlence to fit went Into servlce w~ththe company on July 24th of that hlm for command of a hovercraft In commercial or mllrtary year and In the first five months of operation carr~edover use 116,000 passengers. Seventy per cent of these made the hovercraft journey in something over two months from the Operation and Utilisatiol~ W~ththe broad experlence gamed by the two companies beginning of the service. Th~sseemed an encouraging start, but the operat~ononly contlnued to funct~onbecause of to draw upon, Hoverwork advlses on the operat~onand the cons~derableefforts of Hovertlavel's englneers and the utlllsat~on of the craft whlch IS of vltal Importance to a very great co-operat~onfrom the designers and bu~ldersof potentla1 operator as soon as a decrs~on1s made to try and the SR N6. At the beglnnlng of the servlce, s~xtycrossings explo~tthe uses of hovercraft. The vlabrl~tyor otherwrse of of the Solent were consldered essent~alper day and because any proposed route 1s thoroughly Investigated and the of this hltherto unknown utlhsatlon, components that were enqulrer IS left In no doubt whether a servlce has potential meant to last for years were giv~ngtrouble. As a result of and how thls can best be handled. The prellmlnary stage the extenslve overhaul and malntenance experlence gamed of the lnvest~gat~onconcerns route surveys and many from these problems, a very rap~dadvance was made m factors havlng an effect on the servlce are consldered, such the development and operat~onalknowledge of the craft. as population denslty in the viclnity of the terminals, navr- Further exper~encewas consldered necessdry for the pur- gat~onalhazards, seasonal Auctuat~ons,compet~tlon from pose of wlnter operatrons and the servlce was contlnued exlstlng transport servlces and the presence of a potentla1 throughout the ensulng winter freight element Early In 1966, Hovertravel had its own shore-based radar V~abll~tystud~es are the next stage, where many complex and clearance for n~ghtoperat~ons was obtained The com- factors are analysed, frequently requiring special~sedtech- pany's second SR.N6 arrlved In May and soon afterward, nlcal knowledge These can have a profound Influence on a scheduled service was offered w~thdepartures every ten the success or fa~lureof a proposed servlce and a typlcal mlnutes and with all seats bookable In advance Durlng example 1s the provlslon of radar ards, whether shore or 1966, nearly 256,000 passengers were carr~ed,representrng craft based and the expected utillsatlon of the equipment a load factor of 56 5%. The malntenance troubles referred Many considerations such as thls &re not necessarliy to prev~ouslywere still apparaent and Involved operat~onal obv~ousand can easlly be overlooked or decls~onsmade costs consrdered much too high by the company, even tak- whlch are based on incomplete lnformat~on mg Into account the fact that thls was a new servlce wrth Under the headlng of comprehenslve route studles are a new means of transportat~on grouped the part~cular aspects of Hoverwork's actlvltles At the present t~me,the englneerlng costs of hovercraft whlch Includes the second~ngof craft, p~lotsand englneers are usually closer to aircraft rather than shlps, wlth the to a proposed locat~onon charter for an agreed period An h~ghly-soph~st~catedequ~pment In use. It 1s thls equipment operator need not commit h~mselfto consrderable capltal whlch necessitates speclal ARB ma~ntenanceprocedures, expenditure by making use of this servlce, untll pract~cal these belng slmilar to those used for Publ~cTransport Air- experlence has been gained of the route In question and he craft, Overhaul and inspect~onmust of necesslty be expen- IS certaln that investment In a craft and tralning w~llbe justified Overhead costs can easily be overestimated and the manufacturers of hovercraft, the consumpt~onof sparer this IS another sphee where an exhaustive investrgatlon at In servlce 1s a partrcular sphere of Interest, as also 1s the an early date can pay b~gdrv~dends to the operator, as he procurement and forwarding of varlous spares to any can then have materlal on whlch to base hrs structure, destlnatron Charter servlces are a very rmporlant part of servlce schedule and publlc~tyin the certa~nknowledge the company's work and these usually take one of three that these arrangements will not have to undergo sudden forms. They can be seasonal charter, r.e., at certarn trmes changes, servrces will not be cancelled or disrupted and the of the year addltronal servlces are required that do not travelling publrc w~llhave confidence In h~sfuture state- just~fyan Increase In an operator's fleet; lease-rn arrange- ments. Thrs 1s of very great Importance, particularly so ments, whereby craft that are seasonally surplus to an when lt concerns what 1s a relat~velynew and untrled mode operator's requirements may be chartered by IHoverwork; of travel or ad hoc charter for customers who are not hovercraft operators themselves but who want the servrces of a hover- \ Other Services craft and personnel for a certain period Activities of Hoverwork not yet mentioned Include the It 1s hoped that the brief description of the various management servlces which can call upon experts in every services offered by Hovertravel and Hoverwork will draw field of hovercraft activity and can train local staff to carry attent~onto the vrtal ~mportanceof malntalnlng these com- on the operations when the Hoverwork staff leave a panies on a vrable basrs, so that all these funct~onsmay be partilar location. performed to the best of therr abrl~tyand the vast amount Advice on spares holdings is another service undertaken of operating experience gamed in recent years can be used by Hoverwork and here, because of the company's close to further the interests of Brrtlsh hovercraft. affiliation with Brrtten-Norman Ltd and association with

PEOPLE AND PROJECTS continued from page 23 Textron9s Bell Aerosysterns Con~panyhave annclt nced Wrth the object of contlnulng drscusslons wlth Scan- that it has been awarded a $1.2-millron contract by the drnavlan hovercraft operators, started In Gothenburg Naval Ship Systems Command to modify and overhaul the earlrer th~syear, and of ascertaining the requirements of US Navy's three patrol alr cushion vehicles (PACVs) and the Finnlsh market, Hovermarine Ltd, Southampton, are the crews to operate and maintain them. taklng part in the Navigare '68 Exhlb~tron rn Helr~nkr The armed and armoured SIC-5 ACVs, which can travel (September 16th-24th). The company will be represented at relatively high speeds over land, water, marsh, mud and on the Brrtlsh Hovercraft Assoclatlon stand, and will show snow on a thick cushion of air, saw combat for eight models of therr HM-2 sidewall craft, of whrch two have months last year in Vietnam. already been ordered, and the~rHM-4 125-ton project A The craft were supplied to the Navy by Bell Aero- full-scale qectron of Hovermarrne's glass reinforced pla3"ics systems and have been based at Caronado, Calif. after h~0xtll also be drsplayed In attendance on the stand s~i'l they returned from V~ctnamla-f Jan;-:aLy.They are being be LvarD. W Nicholas, assrstant to the technical dtrector, overhauled at Metropolltan Oakland International Airport and Mr R L Trillo, chief development engrneer. in California. After the overhaul, Bell will provide a technical repre- Cross and Jackson Ltd, of Bernard Road, , have sentative to accompany the craft for a one-year period. announced that they have acquired 26 acres of land in In addition to the overhaul, Bell will conduct a training Cork, Ireland, for their new hovercraft factory site. Their programme for 36 Navy officers and men who will operate "Navair" machine designed to carry 250 passengers, and and maintain the ACVs. costing &85,00will be ready in the early part of 1968. They The training will be done at Bell's main plant near plan to build ten machines per year. Buffalo, NY, and at its ACV base in the Port of Buffalo, where Bell operates two commercial SK-5s. The Hover Club of Canada are planning the first Jnter- Among modifications planned for the Navy SIC-5s will national Hovercraft Rally on the North American Conti- be rnstallat~onauxiliary fuel tanks, additional communica- nent, which will be held in Calgary, Alberta, during July tions equipment, and lights for use by the operators as 1968. navigational aids. The rally will bring together amateur air cushion vehicle Bell personnel will overhaul the craft from top to builders from across Canada and is designed to give home- bottom, making them ready for a full year of operation. builders an opportunity to improve techniques and operat- The Bell SK-Ss, which are an American version of the ing skills in competition with other hovernauts. SR.NS Hovercraft produced in England by British Hover- The National Association for Air Cushion Vehicle craft Corp, are powered by General Electric LMlOO marine Enthusiasts, the hover club of the United States, have gas turbine engines. agreed to take part, and it is hoped that homebuilt craft The basic hulls for the craft were built by BHC and from the United Kingdom will also compete. shipped to Bell's main plant for modification and final Trophies and cash prizes will be awarded for the fastest assembly work. They ride on a cushion of air forced time over land and water, and for the best time over an downward beneath lhe craft by a horizontally-mounted obstacle course, which will include a slalom stretch. A fan. prize of $1,000 will be awarded to the Canadian competitor The 1,000-horsepower gas turbine engine on each SK-5 with the best homebuilt hovercraft of his own design. drives both the seven-foot horizontal fan and aft-mounted The rally is being organised by Major Peter Rubie, nine-foot propeller which provides the propulsion. Honorary Secretary of the Hover Club of Canada, of The craft weighs in excess of eight short tons and is Fredericton, NB, and the Alberta Committee of the club. 39 feet long. It has a beam of 22.9 feet and is 16 feet high. (Continued orr page 32) This 6rze nlodel o/ the hover-bed crane was made und displayed by the designer. All the important points can be seen : Tlze i.vell glazed cubir7 ota tlze jib turntcrble and the lift fan air inlets. The retrtrctirrg sltirt is in the dowtz position nrzd so 11ides the wheels

A Nove Crane Design by our Special Correspondent

LMOST anything and in the course of time everything thelr cholce durlng the final year. Thus the course becomes A is likely to be re-designated or re-appraised by tuned to the ~nd~v~dualprojects and slnce there are no students at the Central London School of Arts and Crafts more than 24 students no great problems arlse in Holborn, London. Certainly this was the impression to Looklng round the ~ndustrlalpart of the exh~blt~onone be gained upon visiting an exhibition of student work held was able to Inspect many fresh and novel ~deasAmongst there during late June. the new des~gnsfor nutcrackers, ha~rdryers, electr~cshoe There are several faculties at this fascinating and quite pollshers, ra~lwayroll~ng stock and wash~ng equ~pment unusual school and these cover such subjects as ceramics, there was one for a mob~lecrane fitted wlth a hover-bed furnishings, fabrics, art and industrral design. Students in base Th~sand the very excellent model of the des~gnwas this latter department are requ~redto complete a year long the work of Rodney Lyall and ~t had won for hlm the intensive course in art prlor to belng selected for entry. But coveted dlploma of the school they do not have to have special technical knowledge nor When work~ngon these final year projects the students yet training in an engineering subject. Thus the course they are requ~redto seek the help and adv~ceof firms and pursue starts in a quite general manner but becomes rather bod~eq wh~chspec~al~ze wlth~n the relevant fields A neat more directional towards the end. This is because students file of correspondence has to be gathered and th~sshould have to in~tiateand follow through on a major project of Include data sheets and other relevant lnformat~on In this case appeals for help were made to Hovercraft PEOPLE AND PROJECTS continued frvnz page 30 Development Ltd? British Hovercraft Corporation and The Navy used the SK-5s In V~etnamon combat river Head Wrightson (Teesdale) Ltd, as well as the British patrols and for antl-guerrilla sorties into South Vietnam's Crane & Excavator Corporation Ltd. All of these con- backwoods swamplands, where ordinary vehicles cannot cerns provided some help and the latter was showing a travel. very llvely interest in the idea. The Navy experience with the SK-5s proved the craft's worth as a kind of low-flying anti-ambush tank to carry The Project the war to the wilderness hideouts of Viet Cong guerrillas. To quote the designer's rntroduction, " This vehlcle was To carry out "~earchand rnterrogate" patrols, the Navy p~~marilydesigned wlth a view to rts use on soft ground needed an amphibious vehicle, heavrly armed to guard quite ullsilitcd to normal tiansport methods " To do thls, it against ambush attack, and able to move swiftly on almost was necessary that the axle loading be greatly reduced any terraln The SK-5s provlded one answer. whlle stlll retalning positive contact wlth the ground by means of wheels One of the most practical solutions to this was to spread part of the load over as large an area as possible by using an alr cushion contained within a The hovercraft's suitabilrty as a sh~p-basedtransport retractable rubber-fabric skirt By doing thls rt was possible vehicle was emphatically proven durrng recent operations to reduce the axle loadrng from 15 tons to 7 tons The alr in the Medrterranean area by an SR.NG based on the cushion is maintained by two commercial centr~fugalfans Cunard crulse lined Sylvuilia Cunard 1s the first company mounted on e~therstde of the vehicle1 to carry a hovercraft aboard one of rts llners to run Basically the project coilslsts of a crane mounted on a sightseeing trlps for passengers at the varlous ports of call. roadable chass~s which embod~es a platform of some British Hovercraft Corporation staged technical presen- 70 sq ft (6.5 sq m) that enables lt to double as a carrrer tat~onand demon~tration runs for potential commercial of considerable value. Tlze air cush~onfeature enhances the and nlilitary operators, local clvic dignrtar~esand other design In all tts dutres and if bu~ltthe crane would be of VIP7 at the following ports. Las Palmas, Lisbon, Gibral- great value on construction s~tesand In rough open ground tar, Malaga, Palma, Malta, Messma, Ajaccio, Tangier. storage areas It may also find use on gurded mlssrle sites. , , Famagusta, Beirut This BHC programme The controls for all the crane actions as well as those was most successful, the SR N6's overwater and am- for mobil~tyare gathered in the well glazed cabln which phrbtous performance rnalclng a great impression on our rotates with the jib. Thus for general manoeuvring the cab guests To give ~tsclemonstration In Tangier, the SK.NG can be rotated so that the drlver faces the way he wants made the first-ever hovercraft crossing of the Staits of to go. For general road work, say from slte to site, the 11b Gibraltar would be lowered to the platform and face the direction At Athens, H M. King Constantine of the Hellenes rode of motlon In the craft, taklng the controls for a short perrod He was Dual wheels are mounted at the forward end while those later repoited to have been extremely impressed by the at the rear are single and stcerable. All the actions of the SR N6's performance in a 25-knot wind and v~~tlla very crane and the drlve for mobility are hydraulrcally powered. confujed sea state The source belng two pumps mounted at either end of a The SRN6 was aboard Sylvanla from the end of transver~elypos~tloned power plant Of the dlesel type this Fe4ruary until the middle of May. During this period ~t would be turbo-supercharged and capable of delivering operated on forty days and made eighty-two sorties Some 300 bhp Maximum road speed would be in the region of 2,000 passengers were carried at fourteen different ports 25 ml/hr (40 2 km/hr). In twelve countries The British Hovercraft Corporation advised on the size The programme showed clearly the practlcabllity of and type of fans that would suit the purpose and provided operatlng hovercraft from ships like Sylvunza, and of main- several baslc deta~lsnecessary for the deslgn work Uslng taining good serviceability over an extended period wrlh two fans the details are as follows the craft stored in the open in a confined area, and with Flow Volume only a small operatlng crew Duri~lgthe Sylvnr?ia crulse, U/sklrt Fan Pan per fan hovercraft operat~onswere not interrupted once through Clearance shp RPM CLIFt/min unserv~ceab~l~tyThroughout the period, the operating 05 ~ns 300 3,800 450 crew comprised j~istone Commander and one Engineer. 0 25 ms 150 2,700 222 No problems arose with lifting the craft in-board or Centr~fugalfans having a dlameter of 2.75 ft (0.84 m) out-board by means of the standard ship's derricks. The and approx~mately1 ft (03 m) deep fit the req~~irement$. liner's handling crew soon worked out a successful Two fans of this type are mounted under the raised turn- techn~quefor lowering and rai5ing the craft quickly and table part of the chassis and are fed from louvres flush ~moothly,and for avoiding "snatch" loads in rough seas. wrth the slde wall of the veh~cle C,"ushion area is approxl- More than forty llfts were completed without incldent In mately 135 sq ft (12.5 sqm) and the pressure is qurte low varying coilditlons of wind and sea On average it took It appears that each fan would have its own power source well under a quarter of an hour to lift and stow the hover- Whilst employing the hover cushlon it 1s estimated that craft after a sortle the crane could 11ft at least 5 tons at a 10 ft (3 m) radrus Passengers were successfully embarked and d~sembarked and poss~blya lot more The designer emphasized that the at a small platform bullt at the foot of a standard outboard fan esttmates were very pesslmlstrc to allow for unknowns companionway Here again, no problems were encountered such as duct losses and intake blanketing The basic unit even in qulte rough condrtions, with swells up to five feet would weigh 10 tons. The craft's Commander found no undue difficulty in cast- Wlth his studles finished Mr Lyall has gone into lndustry ing off or making fast alongside, even rn cross-wind to work on the design of heavy rndustrral equipment It conditions is to be hoped that the germ of thls crane Idea is not allowed to dle