Some engineering aspects of hovercraft and its place in the transportsystem - The influence of the hovercraft on ship design of the future

HOV.A2T

LCT

12 (A)

h9

n'4

,/ £e

4d

2 Ad

L

/4

4

(a)

ThE ThYLUC OF Th HOYCRAPT O

IP DIGM

OF THE itn.E

A LXTJR T

Bi PR.3ZNTE) TN aOTI'DA?

Y 16.

C.

LIST OF SLIDE

Fie. I esistanco of typical ditplacenent craft. i&. 2 Speed and draG

Fi.

3 Speed/weijht envelope of civil craft operating over water (without Hovercraft)

L K C T U R S N 0.: 12,

HOVEACRAYT LZCTURE

It is now reoogoised that the greatest application for

Hovaroreft in the oonercial field te in the roh

of a high speed

boat or ship carrying passengers or low density sargo.

Thsre are, of coures, aa

_{applications over land, but thee}

generally depend on the typs of terrain and in under davslop.d areas

are considered in the light of existing facilities,

If one considers developnent in the transport field over. tbs

last oentuxy

the motor oar has increased in speed frez about 10 edles

an hour to 130 m.p.h.

The first passenger tram had a speed of about 10 miles

on hour

and today one can travel by rail at about 100 miles per hour.

The tiret passenger aircraft had a epsed of eoee 60 m.p.h. and

today it is iuite comonplace to travel by air at epeets of about

600 m.p.h.

These three modes of travel have each improved in speed by sees

tenfold.

Although passenger carrying ships have al so increased in speed,

the fastest liner today travels at only

_{35 knots und it appears that}

farther improvemete are not poesibhi, and

_{a barrier to increased epàsI}

cxi etc at around about 30 knot e.

There is a very ftzndaziental

_{reason for this M this is the}

hich water drag for dipiaeement vessels.

IDENQ. i.

-2-The first slide shows very sicply the relationship between

the resistance of a typical displaceient vessel and its forward

speed.

The lower curvi thaws the wave resistance due

_{to the}

prea?ures exerted unoa the water surtac.; this we see is negligibi.

at low speed, but increases very rapid].y with thoreau

_{in speed.}

The difference between the two curves is skin resistance, which to

the first order is :'roportional to the

_{squars of the speed.}

_The

figure illustrates where cargo ahipc operate for

onz lisu

ecunc

and

how far up the rerj.qtanca curve the Atl&ntie

_{liner operates, athough}

it obta1n

a very

fnererent in speed.

This then was the rroblen of a few years back - how can this

meres-o of renpt9nce vrth reed be overcorne

_{to ezabl, craft to}

operate at high

eed

_{eccnciieaiiy en the water 'urface?}

By

:loytn

_{the Hovercraft -rinciple, the skin friction}

_is

virtually &t1:inated, by st%ftaining

_{a cuhicn of air beneath the craft.}

In tercis of the previous

_{11de, the increase of resistance with}

sneed t' reduced to e very et'ì fraction

_{of that of th dizniaoemcnt}

craft. In fact the Fvercreft toes further

_{thc.n this; becauss of the}

air cushion the water pressure acting on the craft iS independent of

speed.

Por the same Prcpu.siye

_{rower the speed can be increased by a}

factor of 4, as shown in the cttagrexn and Vie only liIsitatiQfl is the

aerodynaz,ic drag.

(SLIDE

O. 2).

Lot us r.oiider vey briefly

_{the case for a new tye of veMole}

frofl the

_{oorat1oni roint}

_{f view.}

_{To ¡irìke a cose for a new vehici.}

we ut a'c the -uestion "are

_{existine vehcies enrabie of carrying}

out

_{atifactoriy rl the trs»ort work}

_required.

(SLIDE NO.

_3).

-3-This next slide shows the

weight

versus speed envelope for

existinj; cosercal viclea wl4oh operate over water. In the top

left-hand -ide there are reitively low speed ships whose weight can be as nuch as lOC,OOC tons. In the bottom right-hand aids there ars the aircraft, both fixed ìr.d rotar' wing, which have a weight lizdtation

of little nere than lOO tons. The present trend of aircraft develoent indicate that they wilt, in th, next decade or so, fill the dotted

area.

Between the two :-iajor types of vehicle there are a few

srecialised craft, which pernte in cparatively ssaU mwbcra.

These are the hydrofoil artd hydroplaning craft. At the present t1 thaca

two

foras of vehicle do not neki a significant

contrtbutjoa to oercia. transport arid, tren the diagrszzi, we can see that the real choice lies between the ship, which carries a large payload at a low speed, and the aireroft, which carries a snail load at high speed.

In

_{this central area the case te ubsitted that a Hovercraft} operating at interacdiate speeds earrying payloads of internedjat

size will fill this very significant _{gap in the overeater transport eyatea.}

There are seveal nethods _{f sustaining}

_an

air cushion, each p,.thod having its own tartiaular applicst_ton.

.IDE NO. 4. shows the three nethods.

Air Bearing:

This eiplyu Vicus effects _{arid needs relatively flat surfaces}

with a very a11 clearer.ce.

A high pres'ure euply is used to produca

a cushfo

hetween

the rad and

Its

bearing surface,

it is only of use

with

tr2ri.-ort _{ystsrs e'ioyirg rails or flat}

track..

(The Por4

LevansA ute' this idea for a railway 'ystem).

Plenw Qiber:

Air lea&

arounA tnt- jerihori with tht

fern.

Th

tota

prezauz

rioe th the fon aot

on

the underside

of the

lenu ch.aaber

t

lift the craft until eiltriun ta

tablihed. The

power reured doenda on the 1eake rate of thern

air aLld

grtdr clearances

tre re4uired than

with the

Levapad, so

that a pLiun ohanber craft will rile oez-

oLtd o'ostaclea.

This

nethd i

auitable for low speeds over rough ground,

Staple Curtain:

This is the Hovercraft concept

a reri.heral curtain of air.

The jet ini;ialli r,rocluceo a positive

rea rwe ua1er the crft,

hi.h

then dcfleeta th.

eùrtan outwrta to

_{a seal for the cushion air.}

At

re'eit

'ono 4O

.ess rower i

rei.irtd to btin the aae ground

eleors'ce, or hoverheiht, than a rienun chanber craft.

That 1oes this

cushion

of air do for the craft? It provides th. greater

speed oaability. It makes a con'iderable contribution to the

behaviour in ru&a seas in reducind the re»orse of the craft in

pitch

ari heave,

provi'es

asseners 'th n ¡roze corf,rtnb1e ride.

It also provides a truly anrhibious craft and dispenses

_{with the}

need for docks or berthing facilities.

There is, of course, a price to pay for all this and

_{this is}

in the power required to lift it aboye the surface.

_{And the next}

løvoì:pai.:t should be concentrated

on

reducing the power required,

Several proposals for this are xentioned in

the

next

part of the

_lectw.,

Pow the stage has been reached v.here the

_{various annufaeturere}

are either ready,

r soon wi be in a poattion, to offer custoners

nell aud ;diun sized craft at least for cv: ution and route rroving.

L the aae te, de1IA.r

'are wcrkth

n

che. ea for considersb]y

larger and oore so-hi.ticated craft for

;'rtder range of

operations.

¡iv on the pzib1eaa coneit cf refining the original

ooacot to .iuet the vAriou5 seds, size. and

oAtiguztions and

pyzioai oparationa]. coditiuna iii.eiy to b. posed by potential

ou s t ers, vho

ill wait aoun

and ec ìn.i. orbit.

jwITh

O

i?t sIr4

CE 2 h

RESISTANCE

O

TYPICAL DISPLACEMENÍ CRAFT

o O 0 I 2 F' I I Fi ) i

il iii

VICIfRsAnM5tRo,dG5 ARCRAPt) LTD. SOU!H MARSTON WORK

J

.

______

-_.I

I 4 :

:.

:::

! : :

:::: :.:::::

t '

::::: .::.:

:::_:

---:T::"

:::.:...

I.iI:ui

...:...::::..

'

¡

:::

!

UIuIflhi*i):

ni

-..,'?LIP!i:

_______

.:::.... '....

::::

LI

:

::

::::

::::::

Hi

____

: :: ::. :. ::: :::

.:::.

:

:::J:::

P!

IIIIIpILhul

IIÍØI

-. .

LL:

'

::

uti

-:.,

cr

'

:1:

L±

i L L

-

:'t -I .1

JI

r:

L:

;P-;

T

ir

_IFJ

Jjj1jjjJ-IHIIOIffiii

s s

I

tA)

SPEED WEIGHT

ENVELO

OF

CIVIL CRAFI OPERATING OVER WATER

r I I) O laC) LIO li):) 00 a

JL

Vffff/ff4

SIMPLE AIR BEARING

SINGLI ANNULAR JET

HOVERCRAFT

ALTERNATIVE AIR

CUSHIONS

L-PLENUM CHAMBER

A

/

/

VIc&8..SThO11GS (ANGxN3) u'z

VAPT

LCT!

12 (B)

(B)

¡ziicwi

01 flOYFCRAPT

CD(EThG

A LSCJR TO

BÌ PRESI*IThD

fl

BO

DAM BY UR. (. C. K

Lect. 12.

LIZ? OF corrm

i

DE3I

nmoso

2.

MEcHANICAL DIG

laI#t

Lyout

Strsogth

Water Impact

.3.

PESfT

Arr

-1 i

V. A. -i

V.A. .2

V. A.-3

4.

FUflBK AFT

De1oped Air Curtains

Ict. 12 (B)

LIST OP SLD

Pt. I Wet,jht analysis

i6. 2

Suctaze d1aon

Ptg. 3 Source of resistance to tioa

Pig. 4 Water inpect loading cases without rotaon

P*.g,. 5 Wat.r tect loading caece wi rotetion

71g. 6 Sl-II ovar oater Pig. 7 V.L.-1 water trials

Pig. 8

V. A. -2 traaspartioa 000nta

Pig. 9

Y. e -3 geteyal -angecent

Pig.IO

Driver's controls Y.&.3

71g.11

Coaponenta V.A.-,

Ptg.I2

_{Y.A.-3 cobb 1aloe}

Pig.

13

Spss of

øov.r..tt air

curtains

Plg.14 Actuation

of

flazible øoverott

ecture 12

IGII

nosoI1a

The first question - what is a hovercraft? _{¿t i.}

_essest.

i.Uy s ourf.oe vehicle lassonch that it relus upon the

_fus

ionedistclj bassath it for it. support. _{The hovercraft is} unique "iig.t surface vehicles however, top la its basto esafigurstion at liest, it doss ont cons is ooat.et with the suface ovu which it operates.

There ore s usher cf problema associated_{with craft et}

th

_{rps, pu'tioul.ply ibas opusted ovei water, and it has} been considered dosirabi. to

_¿saLgo

_{and asaotue a onli}

craft, for their investigation.

ofinj5g Hovercraft groud-olsasano, performance ther is a direct interchange betessu all-up

_wsight

_and haves-height ovar s rangs of values. An st.logous _{imitation to}

on

aircraft does apply la the abili, or otherwise,

_of

_the Haver-craft to olear wavsa of s given height3 operation in partial contact with water gives an increased fuel _{oonsunpticn and} s reduced radius of operation.

Thus, is the dov.lojinsnt of these _{craft, control}

_of

weight bas been carefully considered, _{balanced 'g-4-t the} desire for, los proction coats _{Tb. structure has bess}

considered on s mii Leva weight basis _{cospatibló with the}

usi of ectabi 1'hod sauf acturing facilities

There material sises bave bees datarained r _{the strength required, airsr,ft}

stressing

practise has been said.

Xn the ¿saLgo and manufacture stage certain practices have been

adoptedu-The quaii' of estensi. _{processes, and workmanship,}

havi been maintained to a

_at.ndasd

determined ' the

natur, of th. structure _{- whether pnimax, or second.a...} and the atrsa level the

atructue is

szpeet.d te support.

Corrosion protection la provided either by the

choice of compatible esterials, ky _{the use}

_of

In the absenos at recognised acceptance standards, the deai materiale and components used in the hovercraft have been specified Vickers-Armstzongs (gineers) Limit.d,

baa ed upon mom- years experience of sireraf t strength_and

safety rquiremcnta, suitablj modified and having dus rsgezd to the iàtrinsio safety of the hovercraft.

A great deal of dvenae scheming has been done at Vickers-Arustronga (gineera) Limited, on hovercraft eap.ble of opeieting over open seas For the type of seas likely to be encountered on unprotected waters hóvercref t

sizes from 100 to 1,000 tons should be considered. Such siseo are dictated r two teeters.

Firat].y _{tar open water operation .1.1 tough the year,}

the wave coditions require longer craft, with greater hover height. This io to keep the struotcral loads and power requirements to reasonable values. The second factor,

which erives rrcm the relationship of cushion area to perimeter, leads to improved econoi' et operation in terms of ton miles per borse power installed. This la due to the relative saving in power and the greater disposable load

n the larger craft. Thus the larger ranges requiÑd for open sea journeys become economie in terms of fuel to payload

rat io.

The structure of a hovercraft is largely dictated _{LG' the}

impact boda In the first designs, adequate clearance was

provided ty hoving higher powered lift systems, since the structural penalties in designing for greater impact are prohibitive.

In general the development work being carried out on

hovercraft is c,imed primarily at two things:-(a) reduction in capital cost of the craft

(bj reduction in ins tailed power and fuel oonaumpt ion

In the f itt problen, an attempt is being made to get away from expensive aircraft methods of construction, which were and are currently cieing used in order to achieve a

New asterial. are being considered end in particular the use of tetis-tabu etrasterie is receiving attention.

On the question of installed power there

is

a traaendoa coop. for novel ideas The

niiti1.i

3St p. of curtejo aequiros less litt power and ease flow than th. plonu. obsaber typ. of cushion, yet the power requirexaast. suggest that this

type of craft vili not bay, general application, but will be restricted to ap.oi.lia.d fields, transportation. What anat be borne ta atad however is that the curtain doca no wort and nature bu cot no liait on the reduction in power that night b. sohieved.

Lec

i2

1*'QIMIci1L DESIGN

The toro 'Usvercrat' was that giver by Coakerall to his

invention of te sn...&1nr jot

aho

in thsae firee oad

develop-miata at it.

_{M-tfect nachin', a tore iod piøularly}

by the AiMna, inoledea all 4r cushion croft.

'The none

liovszsft' baa ace b.e

adopted se the Registered Trade.

f or H1L aed

ir aasoQte5.

Sisas te pocer reçti:ì i: 1re1y ajnicnt on tbe Uft

?rovi(1.ed cad honco o

_{tio tottJ. ;;i;ht of the craft, it foUo}

that the ratio ei:

j10

to totoi (

2-"-7o!.t)

e a oaee

of eftiotsuo

ua rfecto tho cgt of opraticr aíì1ficantly.

flamee centcl cr

i ceratuUy assessed aM balanced ainat

the doirq roe le.. pct..oi cots.

At the pto.ct ote, eod layct.t, cozotuliy iolecteil aM

oate'icod opÛ.3tioa

r

.tronenta, s, the choice at the

correct pOvez'/weht ratioo

u.n oI..l resuit in I...r-e wei1it aaviDßs.

Thess foatorsa aLU not cost enytMn sad vili te fact redues

the first cost or the cre? t. Th' can, !oov.r, only be eoath»ellsd

la the epeciftonUoc tant initial pro..ct staee, sthlto

to date

ioate that L'1b. I is s typical wctht bresdin.

Ltycii' i

Fis. 2

ivoa 1taarrat1r

vicos of a ty:1cai Hovororm2t

lauont.

The 1er d.tau.'

phasisoa t:o

eaentiai foab.zres at

tJ

_{ßovercrqjt, viz, a ztatic air cua.zion boncath}

_{o oratt o?}

prosawe higher ')wa to:"r!.c ml !al

fr

zrtr5n which tices

Pror the orart to Je Ot

« it1

o

tiic cruft's

yeriphery.

Thu ai cTtfl ?.ttfl..' t

_{prcsu'o and}

seals It Iroin tLí.

tcrr, h

t

.

whiei

pro-vidse most of

tìia

r!vt 1if. Ia tLt. çft ti.. air £,r the

ctains is t&cn ints t

craft tzow

intaloas iii the upper

stu1ee, enert.i by

of tan oentrjfuai f tai au ducted

ctt to the edre et' thu craft.

The farl3 are driven b;' pceer uidts

a oua.d buoyamey taz

. o:

c't to .bat

O

uIituL WA neoaas%ry.

In the upper diagran, superitructure and control surfaces

arc addsdj the latter are for steering the craft and waking it stable. An aireczew provides propulsion force. The crow arc aoo'o4.t.d

la

the treat of the

croft sed

the poyload, which nay be ¡*ss.ng.r. er

freit, te

carried

ta

the centro.

Poer:

e p

.c.a o? 71-.

3 is

tu

tiiu?tr..te ti

vrtou 'urcc

et ronirtco to the motic.n .f Hove'uzaf t. For i croft operating ovar t hard aurfce there are three ounIronte of re2lstance on drag aM s fourth cowponnt eben

_oieratin

aver yielding ,urfs000 cueb se vetar.

The ne radynanic 'rof11e drrj' te te rcsietucs incurred by any

body aviu tuh air ani'. trkes the fz

f ¡.rrue

t

crtt

surface

end rhearii

force

u, t:

fz4et1i.. The 's tiLe dr.' ir

saooieted 'ith the uses of tr túen tnti the ertt to the air

curtains. Tb. air is speeded up tre rest to the speed of the crcf%

bsfors o3seted with subetoatially equal velocity

la

all direction.. This speeding up of the air baa a dreg force reaction

_ca

the intabas.

The cuahios drag is due tu resisting the novenent of thi cushion tbrcu the *i,, As far as the free stroan is concerned, it resistu nation of the air cu!hion i. it would a solid body.

The catar drag is associated with wave-caking

_and

_{cones about due} to slops of the water beneath the craft. _{It is easy te see how a} resi.tanco io exerted on the air

cushion by the

_{water because the torse} nore'. t th' surfac. has a renrward couponciit, but It is _{ot snay ta se.}

how the

_{water drod}

_{nd the urtte drs}

e; transaitt,j

_{to the croft.}

In

effect

both

1 1.he. Lrug cor'nnnts

tru to ioke

_{t!t. er*ft twe rore-up}

att.itnde

n,1 then th

craft ha..

dreg, for the

_resutiun

_{of the air}

eusijiun

iadsr.iafr,oe

th

!1.rt

jTíijfl4

'..gis.wL.rù:'.

If

_he

at.ttue of the oì.aift,t

I'.e:.t hrtaa.nta'. h .n :. :'"riate oontr].

movenent then th penalty i' neyed in a different way. In thi, cose cene

of the

front curtain flows to the rear of the craft - it is net

_than

naking s

/iubstantial

subqVntiol contributios to llStinj the enti sad is sttostiv.]

a

loas of power or s z,dussd hover h.it. Not. that the Hovsa'onaft sia

be tilt.d, io

helicopter

fashion, to obtain s toros la 007 direstia* st

the

price

st redooed hover heidt.

e cue- co.i4ered

vs bees fron 4r.nft nstiss a

fors the

bsis r r

i.sftu4 :r wiUah

vil Heverassit, Vr sisisfl

t2;s.aont tio o.itt ie

000ai44z'sd

1* a maker of ropre..nt.tivs

ccd ¿o s

ibriia ador

aìppll4

loada aM roa.tivs

Tity gid inertia lo&4s.

The

zssl usccelo-t. op.rstia

soaditiam.

pro,1d

bsals ;

eijJ.ii

ani .toseiig to the onr

liait at 5h. ostentai.

It L envi,e,d t.at

io .v:zss Gporatla4, oesiittas. s vuai.5 water

iMbet*.'1tl. v;purts ractivs fczcat aLU osor.

Is tos

ooahisi-borne eM1ticn this 3atsi st torsos

_{3. sddttiv, to the stam}

_{satt sir}

ani

_{tj lcade.}

_{The; cisbbami bid. an 4a}

_{to saver s.srnq}

conditie tus to

'gta

or oo.tni tailors, etac

_{it I. stotlati.sllj}

laprobabt. that adveras vater

sanditica.

and

_g1

or isatrol tai1oz

sou1 sri,

_It

_{s awl presti.. to dsi}

_{to lou.r}

faster. la eaergen sonditiona.

_{The proof and ultiost. tasto,. assisi}

lap

_{that all a.trtsl used for strsss.d parts is to s rscopd..d 5tal4.4}

apsei(icst ice,

_{Lu confbr.ity with sJronstt pne.tis., the}

_{sass. for}

trengtb sr tesesent are ba&ed, u1.s.

_othsnwi.

_stated,

_{ea lindi oonditioss}

i.e. eritin

ihich a's ¿sonad to bs et weh ssv.nit

_{that thq sosar}

bot -c.roir.

The ehc,ie cf such critions

_{.uat nssisaarUjr be sonswbst}

arbi t rtr3- at thia ttee et Hceercrart expirions. and celt lapa7 sposi

aftd,/or

irat,r rount st lixitetis it _the

_{b.hejou. t the matt abos, this}

to b. iesc:cax.

The footers provided

on 'lisiS' condition.

are:- Prost fasto,

10,

An ultinate factor of

1.5 is used in all saies zs.pt

_{crash eases.}

Lest. 12,

Loodin: n's f n

tn

,vhibioup

Hoverorafti Water and around inrcct.

Ccllieion asid *aerpen Ittohing. Beftohing, 3aakl.ng and eltning.

Towing and mooring.

Leoni and general

water

ru

rures on the hull plating.

Control ey.t.. loada.

Tb. sore inportant of the aboye ass now dieeueed ii

detail.

Vtcr t.-set:

The following id.&iis.d water iss»aet conditions ars

considered to

cover

.11 sasse of watr in,a.t. Thess

conditions will arias fron the relative vertisal and horisantal

velocities between the craft arid tne water wñea slighting it

high speed,

or incountering waves in adveres oenditjona.

Cases without rotation:

Casi 1: _{A water fores of twic. tb. weight of}

the craft is

_{applied to a}

_{local area verti.ally}

below the C.G., toCether with cerresroodia inertia

retetion-. _{flise are eoobined with a steady curbion}

lift ha

_flclflt'

the

w,lrht

of the nrnft. _{The total}

unfactor.d inertia force on each nasa le thus thr,.

tines it. weight. _{This case gives rise tu lortgitud.tnal}

ens! tr'taver,e 'Pojri

_berdiflE.

Cas. 2; _{Two 'rater forces, togeter oqúvl}

ti twio.

the weight cf the craft, _ars

_ap'-lied

_{to local areas,}

one at the bow curtain and the other et the _et.rn

curtain, togetner with correa)on(ling inertia reactions.

This case gives rise t, lcr.tudt.

_{'agin' bending.}

Cc.. 3g Tw _{water force,, together equal te twice th.}

weight of the

craft, _{xe arpli.d to beni}

_areas,

_{one at}

tea bow cn! the other at the _{stern curtains, and inclined to} the vertical, up and aft, together_{with corresponding 5nertia}

reactions.

These are combined

_{with the eteady}

_vertical

ciashion lift balancing th. weicht. Ø depese is the in&titjopi of the streight lie. _{oinjn, the bow impact}

noi.itjon with the C.(. to the vertical tbrou _{th. C.c.}

Caes 1z _{Two water forces, together eaual to twice th.}

weight of th. craft are applied along the _id.walla.

Case ₅ Two water

foro., are inclined

to the vertical _up

and aidewcys, to.etber with corresponding _{in.rtig raaotlonna.} These are

_{oombtne,d with the}

_{stekdy cuckiv* lift balcaetá.g the}

coi ht. This caes

4vee ris.

_o

_{atte amd vertical bede os}

the eacees. _{dsp... is the tncl.tnatton of the straight}

line j4ning the sidewall impact _{oaltio with the C.G,}

relative te tEL. vertical,

Cases with rotation of the craft:

Case li A ver-tisai water

_{tier-ca iii}

_{uçplied to the}

forward curtain iet such maitud.

_{as to g.ivs a vertical}

&cceberatje or

8 g tediat.1y above the fores. The reacti,. vertical

foro, on

_{a mass imnediat.iy above}

the

force ja eight tines its weight, _{and elsewhere the veztjsa_1}

reactive force cay be obt-iaed.

A.ditionl tore ar4 aft torees on th ..arse: n'y a;iee _{e to Uz Lortzcnta:}

conpoient

cf

tk rotation&]. ixaortia.

The above leeds er. combined with steady cushion litt balancing the weight of the craft.

Case 2 A? for Cas, i ece.t that the

_inpi.ot

_{force is} tp!iod te the reer curtain,

Cace 5; A vertical _{.iter- Çoioe}

_i

_a.tljed

crito

a.Lgs1 the furo

_ei4

_{aft contrs-ljne of the}

craft,

bett,

tha

forward ai4

_{roer cuz-tgjn,}

Caee J: _{A vertice,' 1irce}

_ir

r:!f.cd along one cde

of .uoh as to _{ivo a v.rtjoal aoceleratjos}

f 4

d1.toy above tb 'crce. _{The izspi.ot toro. a4}

resetlone are

bined

itb

cushion litt ¿nd weight.

C iin :'

aeren

ditohtn:

Ia tIse event of the craft hitting qusya, Jetties, or

obstacisa at the aes wbie t b,ih speed, or, slt.rmstivily, ersih is the shore, the aafctj of the pa.aenr. sad orsw is of ;rtse isportence. Tb, d.ei of the sects sad equipuast support etrgeture within th. o.bi is each tI*t the resulting

bi aceelerftionS in different treetione 5$)' be witbatsed. rs sc!Mtio,

psrticulsr

attentios baa bees paid to the supS of

heavy na,se, erteraal tv t, cabio, -rhieb

sight cause isjuzp it

they break boa, in a crash 1&4g. The inertia terses in teisa antilat, eeoelorstio ore

z-+

!uir

tu

¿

t':

':' ! ;

i:i,.Li :'."ñtt '

Lt. i

12? cflJLFr

T firrt rtou. L r In ::it. ii

1je

F5B,

jut fj:.tr c1 .;hen C.zriIere-R3. ori _{o.i;iijo:ie4 y .he}

tlstioi.1 Zc arci Duvel1.. :t Cr:jr..Lfl

tc

d.-tn ¿v aLLnufctuz.

sa eoii-vt'i raiinod Hov3ror ft. Th or:ft i;e.red in lun, 1959

eni. as t,iutai the S-l. 6

;h,;-.

tc

u

wtsr

t slu f Tt,ht. Ti:.- i _{aecs:.. It t;erforae&}

orieb1y

.i ofu1 'asearch ve1cle.

Psrhse it iu .ohiey,we,i

w.. t,

_rijì

_{of the ehi.nn..ì fr}

Calais to Dover.

Thi: v-1 t. ?s 'ei.

-1f.3

-i.

57.e'11

i:

lt first

c;er.sta! fcr rs.'qrch r' :.'

_{T': lt}

_te

_{-l. wa}

ft

&! it bees. 25 ft. AL 'vis I.,o.ide Lelieoçter ins dsiiviing

435 i..i. rOtd.s litt. At it _{.riral wet;bt of 7,500 lb. it achl.vs4}

o c kotr. and a hover

cf 3

i"n. T. wsght ha. been ¿cubiM

with odifietjø _{nd !ts hover hplht has b.en rodue.d}

to about 1

It now he

rtst1

_{'.le; Vlre- e-.Jne f.,r rrc-iul.j3n and has}

achived

-&out 70 'oiot, over water.

rtef rvt.w of Viok.rs ara%; V,A,-1. R.seareM Vnicl.:

Now with trr; yeaz-

opartic,n

_{a.1iady behind it, this}

seau ver.irile (Pig.

₇₎

_{t. con tict4 of wood end}

fibrejla..

sn ) _{ri,tol SUdney}

psy Major engin 4riviag two oentrifupi. tans

t1 provide lift. The propulejo unit i.

a

35

h.p. 1ru

en,ine hirivin _{a f ixed-'itøh tw.-b1ad. airaorew.}

0pereti; _th "atiepi. autin*

*.ikt of .,3C0 lb. a.&&

a how-p. "ei-ht of 4 _{ins., en xte!pjya}

ro're of test.

was ooepl.t.g.

Iveptl,.tj eover.d

control and etability

probiere end drag _{LsIsureerate and j.rvid.4 sea. insigbt}

La.t. 12,

the prob1.. of Hvu.r ft

_000trol

_{over laM ia siaM}

epasci. _{Over outer a Iyet.a of rprr defl.otica}

.s

üVal.psl. 0p.ratio La t h. radia

_of

_{Map apeM rk's4}

sa pr.4istM loatability; tbt. _{e ovsrqous} v

zat of the bm.

Lateas mdiLiaatign. to the s

I5hioa

azoa

better litt ai1GsataUoa. _{ithaut di.stubiij the litt}

plipui.- iaatallstioa, the herir height via laersaaM

to3 io..

at the _{w.igbt 4' 4,600 lb. t Cotivi3ta.1 agI} of 130 b.j. va. fittsl t., prupsld.a.

Aoe&.ezstioa tbra,k the p z.gio _{vta laprorel eM apsel. t 35 t. 40}

t. wars

rosolai. _{Ths vehiel. is cow fittil with fleu4.hi bv_}

sai

par.t.a st a w.it of 5,750 lb.

V,&..2, Hsvearatti

tI. logisal ousess. _{to V..-i., it La}

4'

tl't1ias ais. aM plaifaxs (vi1, 8) _{but baa}

stzustcr, to jv. o hiM st _{v'iejçbt ratio.}

Th. V..-2._{, whiab ta currently &ìgogo4}

orar lna4 talais

_{is a}

5-ciat voIlais

of

_{about 3 tone 1O.4a1 w.lkt.,}

It ertdosa at 40 kaotz, 6 Loabas oboy. th. suifs, aM i.. poversi

Coatincita. pistoo eng1uius _{- two fu' litt aM oca for propulai}

which _{a total of about .5O h.p.}

Tb. coat iat.resttj tssturs of the V.À.-2. is that it can b. trtnipertM _by ajj'eavf% aM is iotsnl.t for

operstina tkreujbt the veriL, ?: transçort purpc.as, t1 si&e _{f the croft uro}

rosovabis soi tha

bo

_{orna b. z-&Luocd to aiy 8 ft.}

Tb. craft is iit.oiai ¡rivarU.y for _osontz'tj

work, but it oou1

_?°e

a u!efu1 personnel traneL'ort

riblais over abuterai water, It h*r tve rstxuotebli

v:h.eli which ¡vi lt eziol1o$ _over]oni

coaeourrsbility.

V.!, -3, HQvsrcratt:

This i the Vio av .trQne (V,A.-3. 9) ihiqb arrlad p.eoasr! betxeen 7a11rieey and EI'1 this urer. It

sarrtei 24

aar1era1 weihz 12 t9

at 60 ote ani

is

4k(gjs

_{to hover with it. nain boij about}

_{12 lanhea .bov. the}

urfPö.

Pour

Bristol Side1q Turin

an

taz'bios

"g4"ea5 tas

f' Ïitt azd tie fOr

rou1aton, prc'wiis the pasz.

'ft. dis of

the 'eft ebos

as bi on the

iainjs

41.

that eoul4 op.rata

with rsa:ouabl. opaxttona1 effieieç. The nain urp..e of the

sraft was to

ovUe U3stnl infirsatios on epsrsltuj sapabilitisi

tsr use on lnrr .rsft, but it in b.inj dsvolap.I fats

s

IV51lk

wihisli fa its sin riht.

!.*,.i. Paaasnsr Perri:

Tb. prlàdpls

sryiag the iosiga

eisstrijet ton

bIss issit with aM eons ft

south. of oprsttes

hey.

m

s1ete

In the ffxgt trials cf en .C.V,

_as

ith s

_Vokicls

_hoas

petsutialitisa ax' sot f011y

_{oon, priority znact b. ivon to}

qua3itative tsrtin.,

_{iviw as wy !ruuninS houra}

_{a ;oaiibl}

earljr in the life of t.e 'ehislo to onb1s the 4riv.r-t.

_{obt,i.a bandita1}

saperienwi, aM te ieteet any sajsr unrs istthaut delay. _Quantitetiws

asasnlsaent. airs sai. on V.A..-3,, but air. not allowi t. diley

_the

pr.ee. of the

t.eit. 8ubeert1y, the

ehids has opirotsi

_{on a}

trial seisercial rout ivin s noheauld pas rsngeri.carry1sg servies

over n 19 efe route ii sea contjtjo

near the 1it. et the vehie1s

potentiel.

Ai eses out of conf.zt was taksa frs.

_{psassax' sents.}

This su'vq oovers*t operation when eMir

_{tut, incluting ditsbis}

taiog, and wave inpast,

Tb. general

_{aungex' rsation to the rUs}

aleo compared to other paeeensr-oixryisg Isbiol..; scat of the

psassar. tosod the ails. the 'scoi' a, s traiw sai 'bstt.

_t

s ¿asbl*4sak bas, bat opinica was ¿iwidsL ca whathsx the rids ass.

tbè 'ais. a's esa. Is.

l'4''

aaa33rats St paaaissr

is.at1ca'h,. fris the

1 t.

asziis, ace' 3.000 replIes

hey. bis* .t44 caverai 10 trips

er 16 iiar..

ta tú. survq

fammi the jouzs

_{aaooth 4}

_{ssc.ptabls sei l}

_{ecacafbatabis,}

Ths V.i..3. is ais st Sast

astca sei baTh,. isrriag ist

a

_{als.nied sp.zstil. tasis it is t. bi solitSad t.}

_{dv. lt s}

assh - -

i.

sas ibais is Pg. 10.

All soatrols ars dsel4 ti aplaste la their astersi usos,

s.s. ]att aillai tuia the sasSi ta pert. Whew the .i.ft is

he'si.a stattisU, it is f

_{to b. very .uss.ptabl. ta ulM}

sasreat., sei lt ever 1, t. grsdista.

The controls saw ¿4.al

t. SSistS2It the$S.iftiSita u

_{pggjja bat lIròMr.i}

causa of

_{heats, it ii .nsssesu' to head}

_{the sraft ints ojal sei}

asisteis posits with tbias,l

thz'gat.

Wha5 the lift heleas sue roiaet fas

_{speed increases;}

the enti biiao t. lift oft

at a cantata faa opee

_{This speed}

is lasrsa.e4 atea the cr3tt

_is

_{n, hestZjr 14.d. Piinthez raiol.a}

st the levers ivu jasrascad

_{stati. havsa height,}

_{Triisiag st ib.}

sasSi is pite

_{is a.hje,ei b; &tfotcutja.}

_{use cat these levez..}

i

ipalstio 1 the (pzepelisz.)

_{tig'uat lever. ent (ctcs f aireo)}

_eastasi

-kiel oauces the irait to

_{ao, away in the tesized ¿tzostiim,}

Havarie5 st speeds belw l heats (heap drag upset)

_{over catai,}

the üpreaaia

_{is the aster sutaee beesath}

_{the croft ¡iv.. a}

et

'k.t1' stfeat arricting Li over,1.fli .0. Ipift.

niioeuvrin

over .rntor at 51ew ep.cd fe bt øUÍri

sut t

rs4iad.n

ho?er hiht. In thir coitton the ej'sft oSli rts

ik10

convontioruti boat, aoutro1 betn osbteM a1Tost .nttve3

os the rud3.er

a-d uro of ij!far,ntid thsut.

Traveflie

t high isc4 the ratei' .uWss t'. ralattvsly

umiitnbe

sit4 the

o1 .ff.ot i. set pveunt. ui.st. t bus

sind. eust bi eoitrofle* b7 use of tb

?srati'4 fias, but is sitz

saies it usy be nese..ar' to yaw the erift at. the eLM te

latsts

s Iaafre& track.

Whoa ao1d.n

a turs OTS? retir the .ruSt sill veapu te

*ar.

st1utiøn, bet uaLag fro. the .uk of salar bui,

exiSt sill

bugS.s t, sk.i4 *l4swsyà alng the oridasi trssk,

Operctios et the f crward fLua 4sirsss. tM. tsaâuq aM fair7 lar

raliva tersa are sa4s witheut .kU&tai.

In as sserguuq

i...

avoSdases of saUsa ob,trustiou, zapiL ruth

et twn sra ¡ossLb1i ist

1'urm3

i.PT

Let us consider now bow Hoieorstt

eon be mod. onas

off ioiont. Th.z. ars two major eqs of riduSili the_¡owes required to maintain the

cuabionz-(s)

developed

air

curtains (bi mechanical curtains

Recircuistion

la

a po.sibl. ems

if

obt&inthg $ more efficient sir cushion. Developed sir curtaIns

smplq-thg reoirsulstion are shown in Pig. 13. This omoo.$

la

to use the curtain more then once before it la allowed

to rice into the atmosphere. _{The air or .q not be}

re-energised before final dis Ohazge. Por the price of

complication ja dust. deaii substantial reduotion _{in power}

i be achieved.

More _{r i.sing than developing the air curtains is the}

approach of reducing the area of the sir certain however.

The most simple insana of doing this is to

port'y

seal the

cushion vith solid mechera Of course, the members t b.

introduced so that thv do not incur large loads upon the

ore! t. One exemple of this mechanical sealing a to Introduce

sidewall. which project downwards at the sides if tb.:orift

below the surface level. On euch a craft

_{power is}

_required

merely t) maintain

the sir curtain

st the front and rear

if

th vehicle, but the price one pqs is

_tas

loss of tb.

ciph4bioue oapabiliy end also the speed is rsatrict.d some

45 knots. Above this speed the dro'nanio drsg sssoeistd

with dragging the sidewall, through the water exceeds the

power caving dus to the redaced curtain area.

Por general applications over all surfaces the curtain area is beat reduced the use of flexible members. _{These have the}

advantage that the resistance to water and iapat loada associated with the flexible members striking the aurisos are halted.

Pig. 14 sunnarises the different wys in which flexibili

cuy be used.

The general problem is to intodue members manuf.ag

if

flexible materials or members flexibly meimted an the craft'_{s naln}

body which readily respond to waves or rough countly.

The coving - iq be psrauM to rsapond t

_{G the'e .} Tb. first 'cup of flmxibl. Hoveresof

ft.4 .b.

Whiah ers aotaatsd _{osotsoting tbs suIsse over hiah th* ipust..}

TN.

p. bas bun u..d

so

s nusber st craft aitbaugh t _{i. tifl,} roso for da1.p.mit, It Sa ost esacatial for _{isoLai. bcvazaz.ft} to contait the surfas. buever ter _{the aeviog parts of the}

craft bi situated _{cushion pusu. s. illustrated io to.}

escoed pioturs. This _{ps of craft consist. of a snober of o'r'°}

os cella sro _{the peripb.zi of the eilt sod each fleztb1} mted. The coin craft Weight

is

ta ' the central osahion

the outer calla onrsly actuate the f1wth1. parta.

At hidhar speeds ontion of the flexible parts Vili tend to lag behind the waves resulting

_{is on}

increased seen gap between the craft

the surf ace.

Por the fissible parta to closely follow the surface at higher speeds it is necessary for thea to base high_{soosjustjan_s}

_to

receive warning of app osMng waves. _{To do this the flsb1. part.}

mast be powered as illustrated in the _{leau figure.}

105 such s areft

a sensing device and servo qeteu are ssp1red.

Putu _{hovercraft ciploying single er isiti-stage}

flexibility will require s fraction of the installed peau of

that of rigid bovercrsft.

The introduction of flexible neobers permits a pestar desigu height for the nain bc4y of the craft the 1arsr

*dronsmjc -t loada encountered

_{lOr riglA bawsrusIt}

ctrifrig waves are no longera proales. _{Local impacts and}

abras ion are not berne

the sain structur. but Iy the fissible

components,

We chill now consider what future bovepøaft _{coy look liho.} Fig 15 ta an artist's i.pronsjon

of s boverurmjt projeotsa at Vtch Armstrong. end d*siate4 VA-4.

It is a high speed over water craft with an amphibious

oapabiiiy sad is a logical folles-on from the basic concept o hovercraft ac* th. early developeent _craft. 1pica,l data for a craft of this e-pe is as followszw

I

A11Wtght

-

100 tons

Total installed pawir

-

15,000 N. P.

Pqìoad

-

£comnodstian tez' 240

panangere , 2

oars

0ve'all disione

-

140' z 50'

Speed

-

80 mots

iwaven up to 4.tt.

Scheduled service would

continue in ness of wave

height

6 - 7 feet.

uoh a croft would hive an operating coat of the

_{name order}

I

as coipetitive vehicles.

_{Lt enploya ilexible members and would}

operate in coastal or iheltered waters.

_{It could tor atpIe, speiste}

ver the English Channel in spring and early suer, but in winter

menthe it would find that there would be too

as

days on which

operation would not be safe.

Nevertheless, there would be a number

of placen in the world where it could offer

_{a car and passenger}

terry service with a substantial tine saving on existing vehicles

and at competitive fares.

Lecture 12

't

1

bD

BUOYANCY

TANK

FA N

PROPULSION

UNIT

AND

CONTROL SURFACES

STRUCTURE

DIAGRAM

INTAKE

FAN POWER UNIT

(3

Case 1.

Caae 3.

Si4e Kieviition

C4.

2w

Case 5.

Water Impsot Iadin

Csaes Without Rotati.

Caae 2.

S ido

EleyBtjGfl

+

Water Impeot Losdlng CMO5 with Rottj.

d E1evatjo

Csse

3.

-4-Ca80 4.

I

1

Ca.e 2.

*

j')

j

f

VAI

9

' -\'r'?.t "

Frg.'7 V.A-I WATER TRIALS

'

S

'

L- 7A

1ll

"..',.

-,

4.,'---".c

4.'

fr

fig.? VA-3 CABIN INTERIOR

r

s

44$

t

j

j

i:

NON - £NE2c, ISE,o

_{RECieji. A 7?OA/}

¿/vEecLs10

RE

TYPES

O F HO VERC

_{RAFT A/}

_{C URTA I/vs}

S/M

PL.E

_{C.L'e7A lAI}

t

t

'y?

VgcBMT

LRCTUR

12 (C)

VISARMßThOflGS (mns) Lm

(C)

sccs op oiic« op iii

A LBCT.x TO B PRES

IN RODAI 3!

.. OC. KN

Lsct. 12

LIST OP cozrai's

PLaCE D ThE T}tA1J'.T SYS

Sp» 7BCTS

4...

DICT OP1ATD(G- CC3TS

F14. I

LIS? OF LIDES

Sp.

_{ijt nve1ope of civil craft}

operati

_{o,er water (with ilovereraft)}

Traaspog-t systeme

_{- Jourxy tje}

?raogrt y5te!. Fare.

- ata8e leath

overaf t direct nperetin _{coota a33ptjon.}

liovercrat Y.

'L-3 direct operatin& costa Siz.e a4 coot of craft.

Place in the ?anaport

_.yetou

We

retunt

_{now to a tigore shown earlier,}

i... the apoed/

weight envelope of civil

_{craft epatj}

_{over water.}

Placed on

the graph now in addition

_{to the existing}

vehicles are the

pos-sible over water A.C.V'

_{or Hovercraft of the futuro,}

The Hovercrett

_{are divided into three main cluses.}

(i)

At the low speed end

_{there is what}

_may

_{be called 'river}

Hovercraft'.

_{Thon. have an a.1vantae}

_{over existing river}

craft both in fast ocrront

_{and in akmflow watoe.}

Sono

of these may be nf the

_{iznnersed sidewall type.}

_{It is}

thought that the speed

_{rango might be up to}

_{a m,tn of}

60 knots, but

probably

30

to 40 knots depending

_{upon bende}

and other traf tic,

_{and the weight will}

cbab1y be between

1G tons and 1,OOC

_tono.

(2)

_{'basic Hovsrcrsft}

_{axe the conventj] sheltared}

nod

open water craft.

_{It b thought that t}

would have a

ma.zicus speed of 150 knots

_{end there te not onch point}

in going below 50

_knot..

_{The wsight of the craft may very}

trou

_{.ii craft weighing a few toas carryii}

a few people

te something approechieg

_{10,000 tons in the case of the}

Open mater craft.

(3)

A third clase

et

_{craft tensed 'high speed Hovercraft' in}

the graph could

_{cono*iveb].y go beyond 200}

knots in speed

atri would probably be

_{rather large vehicles,}

Thsoe

would

not be oonventjo

_{Hovorcxatt in the}

_{sense of having a}

static air cushion boigided

_{by an air ctrtaj}

Instead

tho front air curtain

_{would be 'switched oft' at high}

speed and the dnomic bead

_{or ti}

_{free a treno used to}

o5!tbuto to cnshion

_pxesn..

It 13 rather significant that

_{al though Hovercraft}

_ciìi

conceivably occu

_{a large area on the graph, this area does}

not overlap tae oporatin

_{erwelopes c' the aircrs.ft}

_{and the}

ahip.

-1-Speed ffeota:

Iitting thehi& speed Heveru f t'fez _{the present, two}

essentially

different classes of craf t, _{the "imeeroed sidewall',}

and the 'free-of-the...'

craft previde two speed _{rouges. In}

tsms

of

craft output the irsed

_{e idewall is the moot}

atact-ive it ¿isla gatact-ives the _{*m*liest capital, outlay}

par craft and the lo,est fares. _{)owever, the economic}

comparison zeast be

in a _{intien with the operational}

features present. valua can be put on the speed _{superiority of A. C. V's.}

icaca-aed sidmj.1 has

a 2j to I advantage over equivalent

displacement

ahipa. _{The 'free-cf-the-ewtace craft has a Ij to}

I advantegs over the aidevali.

Rather then speed, "convenience" is probably the

e powerful attraction to the intenjjn

pasaewger; bez's convenience 1mo_{ludee a meazwe of speed}

as it

sifects the block time between

the two pointa the passenger viches to travel as compared with the alterimtive _{means of}

It is in the context of

convenience that the smphlbiou5 property

of

the _{frei of-the. w'fece' A. C. V.}

gains compared with lb. imeersod sidewall craft.

A route cay be operated not other-wise poasible by reason of ehallow water, obstacles etc. _There is _{e choice in the positienjag of}

terminals and such ter'dnels mey be con.truct

at a lover cost than those requfred by non-smpk4biou_. craft. _{Aise s'ter turn round}

times should be po.-.

aib].. _Development

_of

the itaeersed sidewall craft _{will give it}

a limited

aMpl4hjog5

qnality, say slip-way capability, without

changing

the essentiel mote

_of

_{the waf t.}

_{There iU than}

be a vider choice of termical location..

Pigiwe 2 illustrate. the order

of

the fares gap otilen

snot be offset with the greater _oonveniez

off eremi by the

A.C.V.

Other things

_{being equal fer routea of 50 miles or lesa}

the isotareed sidewall offer,

a Substantial speed increase with little

or

no izoroase in fare. _{Over longer routes the fares} of all A,C.V.

a are

_{coasideraL.jy in excesO o. ahips axtd the}

craft with the ¿as.xizxm

_{spet1 capabiliy will}

prove to be mars

atfractjv..

These ocesideratJons

_{are quite apart}

_{fres the}

mettere of routes, taXInh1l.1A

_etc.

Fares:

The estimated paaaen_g,x fare thet would be eborged on the

100 ton A.. C.V. is canpared,

_{in Pig. 3 with typical fazes}

charged

for ships and etrerart

_{The fare ja. given in terms}

_{of pence}

por passenger mile aid la plotted

_{against the stage length of}

the Jowney In nautical

_miles.

_{As the operating cost}

_{per nile}

reduces consIderably with inea.se in stage length, operators

are able to offer lor taxes for

_{the longer joinsrs.}

Con-aidoriag the ship, we can see f rem the fares quoted for

_the

Isle at ¿iglzt and

ae1 bosta

_that

_{there can be}

_{a conaiderabi.}

variation, The ninj

faze

chez'ged on

boats is about

_{44 anI}

can apply for journys of 20

n.s. a.id above.

The afroratt, although it

can

_{otter oareble tarea to}

th. ship at

stags

lengths of a few hred nautical

_{edles aid}

above,

_{cannot compete at stage lengths}

_{up to 100 nautical ailes.}

100 ton A. C.V. i. expected to

_{otter a ocaparable tore}

to the ship aid the aircraft,

but the

stage

lengths over which

these fares apply are about 50

_{nautical ailes}

_{and abo,s. The}

o1msjens we sdght

draw

tras this graph axe

:-(i)

At 2cv ntae lengths

_{say up to 25 n. miles the}

A.C.V. tare. are in excess of the ship.

The

at-tractions

_{of the Hovoreraf t are its}

_{speed and}

rdiacod loading aid unloading times duc

_{to its}

anpbibiaua nature.

(ii)

Betvesn 50 n,n, and 25G

_{n.a. the A.C,V. really}

omca into ita ona nith ita attctivg

_{apoad cal}

competitivo fares.

(iu)

_{Above 250 n.m. the caso for the}

airca'att is very

strong and the chance of the

Hovercraft would

appear slim on these f

iwea,

-3-It should be borne in mind

however, that the tarea quoted for the 100 ton A. C.V. aroby no _{na eatabliahea_,}

The

par-iouler oral t taken ha s lind ted applications,

. waves up to ore 6 feet significant

_he

ijbt, but on the other band

develop-nient 01'

the

_{craft night ienke}

it

moe's attractive than the _graph

iiLioat.s.

Dfreet

Ctir:t.t.g

Costa

With the introduction of a' new term er tromaportation, the items of prime importano. _{to a pro8pec tive opErator}

are the sise of payload whioh can be carried, the cent of

cerr.yisg this

peload, and the initial coot of the craft. _{Another oonsidrat..}

ion is the development tireo

required before economical operation

can be established,,

At the present ti.iø hoveroi'af

t are being Ceastruotod based on aircraft type etrurturca and

power instaUatjon, and using

atand,arì aircraft onto riais. _{In view of this}

the estimation

of direct operating cot baa _{been based on the cerrt}

method

of esttj'tatj' aircraft

operating costa, _{The reference for} estimating costs has been the S. n.A. C standard method;

in a few instances the formula, have _{been a&juated to suit the} Hovercraft requirmeonts. _{A typical set}

_of

aastiona is shown

in Pig, 4. aM timas have been _{used in øbtin1ng}

crative

costs for various craft discussed in this paper. Pig. _{5 presenta}

a coot amalysis for a smell amt t.

Comparing the direct

oper-nun« cesta

of

tarions iraf t using the _{some standards}

_of

en-gineering construction and

development, although the operating Conditiea are not identical, the

variation of craft size and coat readi3j be soon. _{The trenda due to sono of these} parameters are iliustrat-' in Pis. 6.

-?-101

_lo,

_Io

_.1

SPEED! WEIGNT ENVELOPE

OF CIVIL CRAFT

OPERATING OVER VATER

r- -

_s

I

g%BISB

I

' 'SPICO

I

' Basic

,'

HOVER ______________I

-,

HOVEl

'

ICIAFT #

s CRAFT

i

I

i

,

S

livEl

VA.5

1ROVERCRAFT

$

s

V.A.4,e

I

/

OIL

..

s s

/

4V.A.2

I

T

10

20

50

40 50

100

200

¡00 400 500

SPIElKNOTS

JOURNEY TIME

(HOURS)

3

₂

i

_o

50

100

150

200

G.'

STAGE LENGTH (NAUTICAL

MILES)

a'

NJ

TRANSPORT SYSTEMS-JOURNEY

20

16

FARE

(PENCE PER

12

PASSENGER MILE)

N

.

,

N

A.C.V. s

50

AIRCRAFT

HOVERCRAFT

I

SIDE

WALLCRAFT

I I I

FERRIES

100

150

STAGE

LENGTH (NAUTICAL MILES)

200

TRANSPORT SYSTEMS- FARES.»'

HOVERCRAFT DIRECT OPERATING COST ASSUMPTIONS I. ANNUAL COST Amoetization

-10 years Utilization

-2,000 hours/year Spare8

-10% first cost Insurance

-3%

first cost

Interest on investment

-4%

first cost

MAINTENANCE AND OVERHAUL COST

Labour cost

-7 shillings per hour

Engine overhaul

-Annually

Fan and transmission overhaul

-Annually

FLYING COST

Crew

LI per man hour

Fuel cost

-20 pence per gallon

Berthing fee

-£3 per hour

TOTAL DIRECT COST

DIPCT OFFRATI'

COSTS

!.

ANNUAL COSTS

L

perhar

_-

_19.9

₃

2,

MADT!!iWC AND OV9AUL COSTS

L

perhour

_-

_9.5

2Q4

3.

FLI1G COST

£

per hour

_-

_23.5

4.. TOTAL DIRFOP COST

L

per hour

5.

PAC'T

CJD! S

COST P SEAT ThE

HOV'RCRJFT V ft -3

-

523

10

-

24eest.

-

6Ote

-

lOpens.

e43

F'c, .ç

s

0%

'u

-I

-Oz

u

I-.

o

z

I.-

O20-

I-

u

ow

u

z

io-'u

Q.

60-

50

_40-

o

o

¿

¿

EARLY DEVELOPMENT CRAFT

t

t

PRESENT PROJECT CRAFT

t

t

t

t

t

t

t

t

t

FORESEEABLE DEVELOPMENTS

t

t

t

\V.i4 \

t

'4 '4 '4 4Ir. '4 '4 '4

-4 FT

HOVERHEIGHT

r5

'4

VA4 FLEXIBLE

2 FT

HOVERHEIGHT I FT HOVERHEIGHT 100

₃₅₀

200

₇₀₀

1050

SIZE AND COST OF CRAFT

FUTURE SEAGOING CRAFT

400

A.U.W. (TONS)

60

50

40

30

20

o

NUMBER OF PASSENGERS 2 3 4

£MILLI0N

,.ç=

-eat. 12 i3

r

I

'J.

4

'i

"

:j4

t _{_s} i

'I

+ I

i y

i

f,

,

$r I'

'Jt.

_L.'iJ

I DO

I'

Fiq.