EKRA­NO­PLA­NES BOA­TS OR PLA­NES?

They fly few me­tres abo­ve sea le­vel and they are stran­ge ma­chi­nes part boa­ts part air­pla­nes. Tech­ni­cal­ly they are cal­led Ekra­no­pla­nes and up un­til se­ve­ral years ago, their use was ve­ry li­mi­ted and they we­re de­ployed on­ly as mi­li­ta­ry ex­pe­ri­men­tal ve­hi­cles.

Superyacht - - Design - by An­drea Man­ci­ni

In tech­ni­cal terms they are cal­led Ekra­no­pla­nes they are mo­re spe­ci­fi­cal­ly half way bet­ween a sea pla­ne, a ca­ta­ma­ran and a ho­ver­craft. They in fact fly few me­tres abo­ve the sur­fa­ce thanks to a buf­fer or air cu­shion whi­ch forms be­low the wings ex­ploi­ting what flyers would call WIG in short for Wing in Ground Ef­fect. This is why re­cen­tly they ha­ve been ter­med GEV or Ground Ef­fect Ve­hi­cles. The Rus­sians we­re the fir­st to ex­pe­ri­ment the­se in the fif­ties hen­ce the na­me ekra­no­pla­ne whi­ch is no­thing mo­re than an adap­ta­tion of the Rus­sian term экраноплан, ekra­no­plan. The idea was to de­ve­lop a stra­te­gic trans­por­ta­tion ve­hi­cle whi­ch could equal the load ca­pa­ci­ty of a ship wi­th the speed of a pla­ne. De­spi­te ap­pro­xi­ma­te­ly 40 years of tests, this ve­hi­cle ne­ver ma­de it in terms of sa­fe­ty, re­lia­bi­li­ty and ef­fi­cien­cy as ho­ped. Con­se­quen­tly ve­ry few we­re built, near­ly all of the in the for­mer USSR. Re­cen­tly thou­gh in­te­re­st for the­se stran­ge ve­hi­cles re­tur­ned gi­ven their po­ten­tial, as pe­rhaps ser­vi­ce boa­ts and ten­ders to su­pe­rya­ch­ts. And a Rus­sian- Chi­ne­se con­cern has be­gun to te­st two GEV pro­to­ty­pes, whi­ch could be de­ployed to tran­sport peo­ple wi­th. The CY G11 as per the co­de na­me is pre­ci­se­ly 13 me­tres long wi­th a no­ta­ble wing span of 15.60 me­tres. It can car­ry up to ten pas­sen­gers plus two crew at 200 km/h wi­th a ran­ge of 1,500 km. The fuel con­sump­tion is de­ci­ded­ly low: 28 li­tres per 100 ki­lo­me­tres. In Ger­ma­ny Sea­fal­con af­ter near­ly 20 years of in dep­th R&D, tests and pro­to­ty­pes is loo­king around for part­ners wi­th whom to start pro­duc­tion in se­ries of the GEV Sea­fal­con whi­ch is 13.7 me­tres long wi­th a smal­ler wing span in com­pa­ri­son to the Rus­sian-chi­ne­se ver­sion of on­ly 11.50 me­tres wi­th a car­ry­ing

ca­pa­ci­ty of ju­st 8 and a crui­sing speed of 180 km/h using a me­re 15 li­tres/hour of die­sel fuel. But what has chan­ged in the mean­ti­me , how are the­se any dif­fe­rent from the ones from the 60’s and 70’s whi­ch we­re con­si­de­red as un­sa­fe and un­re­lia­ble? What ma­kes them sa­fe and re­lia­ble to­day? Let’s be­gin by ex­plai­ning what is meant by ground ef­fect whi­ch ma­kes the­se ve­hi­cles ve­ry ef­fi­cient star­ting wi­th ex­traor­di­na­ry low fuel con­sump­tion. As an exam­ple ob­ser­ve the flight of a sea­gull, al­ba­tross or other sea birds. You will of­ten see them fly low skim­ming the sur­fa­ce be­cau­se by doing so their flight pa­th is mo­re ef­fi­cient and they ti­re less! This is due to the ground ef­fect, or that phe­no­me­na whi­ch de­ter­mi­nes two ef­fec­ts: an in­crea­se in Lift (the for­ce whi­ch holds up pla­nes thanks to the di­ver­se pres­su­res exer­ci­sed on the sur­fa­ce of a wing) pro­du­ced by air whi­ch is com­pres­sed bet­ween the wings and the sur­fa­ce of the sea thanks to the re­la­ti­ve clo­se­ness bet­ween pairs of wings and sea; a con­si­de­ra­ble re­duc­tion of drag in com­pa­ri­son to hi­gh fly­ing mo­des, due to a con­si­de­ra­ble re­duc­tion of vor­ti­ces along wing tips. Mo­re spe­ci­fi­cal­ly, we’re re­fer­ring to the vor­ti­ces ge­ne­ra­ted by the dif­fe­ren­ce of pres­su­re on the back and bel­ly of ea­ch wing whi­ch cau­se in­du­ced drag. Ale­xeev Ro­sti­slav Ev­ge­nie­vi­ch a Rus­sian na­val en­gi­neer was the fir­st to no­ti­ce this and was the fir­st to in­vent what is now the GEV. He con­vin­ced go­vern­ment to in­ve­st in R&D back in the fif­ties to fur­ther the pro­ject he was wor­king on, so­me­thing bet­ween a sea­pla­ne and a boat. It is of no coin­ci­den­ce it was

con­si­de­red as so­me­thing stra­te­gi­cal­ly use­ful wi­th whi­ch to car­ry troops and wea­pons ve­ry quic­kly. The pro­ject by the 60’s had ex­pan­ded and Rus­sian en­gi­neers be­gan to build giant ve­hi­cles li­ke the KM1, nic­k­na­med the “Sea Mon­ster of the Ca­spian Sea”by US intelligence. In fact it was a 100 me­tre long 40 me­tre wi­de mon­ster pro­pel­led by as ma­ny as 10 tur­bi­nes and pro­pel­lers whi­ch meant it could co­ver mo­re than 500 ki­lo­me­tres in an hour. It was the lar­ge­st ekra­no­pla­ne ever built. A fur­ther seven we­re built. Ea­ch one fea­tu­red dif­fe­rent cha­rac­te­ri­stics in an ef­fort to over­co­me se­rious hand­ling pro­blems and sa­fe­ty is­sues, de­spi­te the adop­tion of hu­ge tail pla­nes, wi­th whi­ch to ma­noeu­vre and steer, whi­ch re­sem­bled hu­ge rud­der bla­des and spoi­lers.try to ima­gi­ne what would hap­pen when the pi­lo­ts at­temp­ted to bank wi­th su­ch a hu­ge ve­hi­cle fly­ing at 400 – 500 km/h and ju­st a few me­tres abo­ve wa­ter. The slant adop­ted when ban­king meant the in­si­de wing tip would get dan­ge­rou­sly clo­se to the sur­fa­ce of the sea. Ima­gi­ning the con­se­quen­ces if that hap­pe­ned is ea­sy, or if the sea was chop­py. That is why te­sting was car­ried out over the Ca­spian Sea, a clo­sed stret­ch of wa­ter whe­re wa­ves would be a lot lo­wer than in any ocean! In spi­te of the pre­cau­tions ta­ken se­ve­ral ca­ta­stro­phic ac­ci­den­ts oc­cur­red, so mu­ch so that the un­for­tu­na­te ve­hi­cle was soon la­bel­led as so­me­thing hi­ghly dan­ge­rous by tho­se in­vol­ved. Ne­ver­the­less mo­re stu­dies and mo­re ex­pe­ri­men­tal tests con­ti­nued on other mo­dels in Rus­sia up un­til the 80’s when, wi­th the cri­sis and split­ting up of the for­mer USSR, all was aban­do­ned. Ho­we­ver the charm and ap­peal de­ri­ved from the enor­mous po­ten­tial this ve­hi­cle had ge­ne­ra­ted, a lot mo­re in­fluen­tial peo­ple we­re in­te­re­sted: In ad­di­tion to the So­vie­ts , the USA, Ger­ma­ny, Au­stra­lia and Ja­pan all in­ve­sted in de­ve­lo­ping this means of tran­sport, but wi­thout re­sol­ving mu­ch in a con­vin­cing way. Re­sear­ch con­ti­nued af­ter the ‘cold war’. At the be­gin­ning of the new mil­le­nium, Boeing ( yes that Boeing) de­ci­ded to set up and de­ve­lop a new ocean cros­sing ve­hi­cle ca­pa­ble of car­ry­ing con­si­de­ra­ble loads com­pa­ra­ble to tho­se of a mi­li­ta­ry ship and equal the speed of a pla­ne: the re­sult was the Boeing Pe­li­can UL­TRA (acro­nym for Ul­tra Lar­ge Tran­sport Air­craft), it tur­ned out to be 120 me­tres long wi­th a wing span of 152 me­tres and a load ca­pa­ci­ty of 1,400 tons. It would ha­ve been the lar­ge­st ever built.... but no­thing ca­me of it be­cau­se eve­ry­thing re­mai­ned

on the dra­wing board! Se­ve­ral Eu­ro­pean at­temp­ts we­re al­so ma­de in an ef­fort to ex­ploit this ve­hi­cle’s po­ten­tial, pe­rhaps by flan­king it wi­th hy­dro­foils to en­han­ce bet­ter ma­noeu­vra­bi­li­ty and stee­ring con­trol as was in fact was do­ne in the cour­se of the 90’s wi­th “Sea­bus Hy­der” a Eu­ro­pean Coop. Pro­ject whi­ch would car­ry 800 pas­sen­gers and 120 mo­tor cars. As we ha­ve seen the ekra­no­pla­ne is, at lea­st in theo­ry a ve­ry ef­fi­cient ve­hi­cle whi­ch has na­tu­ral­ly sti­mu­la­ted and is still sti­mu­la­ting en­gi­neers’ in­te­re­st and fan­cy whims from all over the world, even if they ha­ve not yet ma­na­ged to re­sol­ve, in a con­vin­cing way the is­sues and pro­blems re­la­ted to re­lia­bi­li­ty and sa­fe­ty men­tio­ned ear­lier. At lea­st up un­til to­day, the new Rus­sian - Chi­ne­se CY G11 and the Ger­man Sea­fal­con seem to point out this tech­no­lo­gy is now rea­dy even if li­mi­ted to de­ci­ded­ly smal­ler ve­hi­cles when com­pa­red to the ones te­sted in the pa­st. In fact mo­st pro­ba­bly it was the ve­ry si­ze of the pre­vious pro­to­ty­pes that was one of the main cau­ses at­tri­bu­ted to pa­st fai­lu­res. So no­wa­days, al­so thanks to en­han­ced con­trol of the ve­hi­cle brought about by the de­ve­lo­p­ment of mo­dern elec­tro­nics, the­se ve­hi­cles’ po­ten­tial has been at­trac­ting mu­ch at­ten­tion even if the co­st is not for eve­ry­man’s poc­ket: A CYG11 costs about 20 mil­lion US dol­lars, but the fact that hi­gh speeds around 200km/h, whi­ch ex­ceed by far tho­se of any na­val ve­hi­cle, when flan­ked by a load ca­pa­ci­ty whi­ch is uni­ma­gi­na­ble for any con­ven­tio­nal pla­ne is cou­pled to hi­gh le­vel com­fort can be ve­ry ap­pea­ling to mi­li­ta­ry na­vies, coa­st guard pa­trols, bulk car­riers and la­st but not lea­st to the ma­gi­cal su­per and me­ga ya­ch­ting world. Wor­th con­si­de­ring al­so is the fact that by con­tai­ning the si­ze of the­se ve­hi­cles they can slot in­to to­day’s nor­mal in­fra­struc­tu­res found in exi­sting ports and ma­ri­nas. Cer­tain­ly if ekra­no­pla­nes de­ve­lop si­gni­fi­can­tly a few norms con­cer­ning na­vi­ga­tion at sea will ha­ve to be re-writ­ten to ac­count for the pre­sen­ce of the­se ve­hi­cles whi­ch would crui­se at the sa­me height off the sur­fa­ce as ships do, but at mu­ch hi­gher speeds. Rea­li­sti­cal­ly spea­king sin­ce 2005 the In­ter­na­tio­nal Ma­ri­ti­me Or­ga­ni­za­tion (IMO) has fo­re­seen 3 ca­te­go­ries of GEV “ships” ac­cor­ding to their ca­pa­ci­ty of ex­ploi­ting ground ef­fect alo­ne, or to fly al­so at so­me re­co­gni­zed di­stan­ce from the sur­fa­ce. Ne­ver­the­less for the ti­me being the on­ly set of ru­les fo­re­seen for the clas­si­fi­ca­tion and con­struc­tion of GEVS (Ground Ef­fect Ve­hi­cles)are still tho­se en­vi­sa­ged by the per­ti­nent Rus­sian re­gi­stry.

Abo­ve, the “Sea Mon­ster of the Ca­spian Sea” to­day - sad­ly aban­do­ned. On the right, ano­ther two sho­ts of the “Aqua­gli­de 2”. Be­low, Fly­ing near the sur­fa­ce of the sea the­re­fo­re means air is com­pres­sed be­low the wings and thus ground ef­fect is ex­ploi­ted....

Abo­ve, the Sea­fal­con: 13.7 me­tres long wi­th a wing­span of 11.50 m it can car­ry up to 8 peo­ple. The Rus­sians’ pas­sion for GEVS has ne­ver di­mi­ni­shed com­ple­te­ly: The Rus­s­sian Arc­tic Tra­de and Tran­sport Com­pa­ny (ATTK) has con­ti­nued wi­th R&D, has built GEVS...

Abo­ve, the CY G11: 13 me­tres long wi­th a wing­span of 15.60 m. Sea birds fly skim­ming the sur­fa­ce of the sea to be mo­re ef­fi­cient, mea­ning they can go fur­ther as they ti­re less! In this mo­de they ex­ploit ground ef­fect exac­tly in the sa­me way as...

Fly­ing at al­ti­tu­de the vor­ti­ces ge­ne­ra­ted by wings are ob­sta­cle free and spread free­ly. When fly­ing low near the sur­fa­ce the vor­ti­ces can­not ex­pand free­ly and they’re com­pres­sed and bloc­ked due to the ef­fect cau­sed by the clo­se­ness to the sur­fa­ce,...

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