TWELFTH EUROPEAN ROTORCRAFT FORUM
Paper No. 63
HELICOPTER INDIVIDUAL-BLADE-CONTROL RESEARCH AT MIT 1977-1985
Norman D. Ham
Massachusetts Institute of Technology
Cambridge, Massachusetts, u.s.A.
September 22 - 25, 1986
Garmisch-Partenkirchen
Federal Republic of Germany
Deutsche Gesellschaft fur Luft- und Raumfahrt e. v. (DGLR)
Godesberger Allee 70, D-5300 Bonn 2, F.R.G.
HELICOPTER INDIVIDUAL-BLADE-CONTROL RESEARCH AT MIT 1977-1985
Norman D. Ham
Director. VTOL Technology Laboratory
Department of Aeronautics and Astronautics
Massachusetts Institute of Technology
Cambridge. Massachusetts 02139
application to tba oolntioa or rotor urodt"a•ic ud aaroalutlc problc•• h duu·ibcd. Bach blade lo ladlvldull)' eoatrolhd lu tho rotatiiiJ fn•e oYer a
attitude ohblliutto ... vllorotlon olhvhtloa, blade h1 da.-ph11 &IIJOIOIIUtlon, 1tall fht!cr npp.-culoo, bhdo fhpplna ou.bilhattoa, otall altnhtioo,
fro• whd tlul"-1!1 tcou of a •ode! holloopur rotor •ltb huliTidual-bhdc-contn•l. The fcuibillty of achicvbJ "'"")' or all of tho appllcattou of hldtvidnal-bhdc-control uol111 the eou·c.,tloaal bcllcopur awnh plate h de•onotrated, aad the aocuury eoatrol lawa aro preu11ted,
1 . lMtllODUCTIOM
A tnoly ••h<aaee4 lldlcopter rotor aaat opu·ate la a UTere aaro4Yll&alo
oaYiro-•ot iaohdu:
(1) u t r u t h l lttada aull {ludlq to hr1• tctroloul loda Ia bide •tractau a11d coatrol ayaha).
(l) bX.do-Torter IIIUuctloa Ia tuaaltioaal aad llllp-<1(-tbe-nrth rlllbt (leadlal to oaacoaptllblo b!Jbcr bnoonic bhdo bo11din1 atruoaa an4 bolioopur 'l'ihntloa).
(<4) bhde-C..uhao lntorhrenoo ( ludh1 to nnaccophble hiJber bano<>nlc biada hndi111 otruua aad bol!coptor Yibntioa).
(SJ bhda and r<>tor baubliltha (teadl111 t<> atn.ctanl hllare or Aon or <loa troll.
Tho app!icatlo" <>£ !ootdbact ucltnJq••• aate It poualble t<> alhYhte tit• ofhcto ducrtbod Ia ltoaa (1) to ($) aboYo, wltilo laproYiiiJ lullcoptor of Indivldaai-Blado-Co"trol (IBC), loopiud by tbo wort or 11. lli:ut~, oabodiu tho contr<>l <>!broadband olutrobrdrnllo utaatoro ath<rbod to oacb bhdo <>r to tbo ... •uh p!Ua, UinJ aiJaals fr . . Ulla<>n IIOllllted Oil tho bhdaa tO aappiJ' appropriate control oo-aado to tho a~t ... ton U-26), Nota tbot IBC laYohoo not just c<>ntrol
ot
uch blade lndopud..,.tly, bat aha a tudbact loop rornd11co tbo uyore ether. of ataoopherlc tnrbnloaoo, rotrntill1 blade a tall, bhde-vortu. totenct1o11, bladc-tnulaJO iatorhnoce, a01.d blade aad rotor icohbllltlu, •bile prO'I'ldiaJ i•pr<>nd por!onoaaco and rtytnc q ... lltloo.
This roourch • n spoaoorcd by tbc Alan Ruurcb Ccctcr, tlASA. llorrett Field, Cdi.fornh 9403$. Special •"hoolcdJ"'""t h du t<> llobcrt II, lill:lli:lll!p, Jr., aad Paul R. Bauer for their contrlb~>tlona at lilT,
c.,.prhed or uvual oob·oyotcno. ucb contr<>lllnJ a opedflc node, •·•·• tbc bhdo tlappint node, tho flrat blade flatolu bendhJ node, the f l n t blade
hi node, and tbc ! l n t blade toulon node {1), Eacb anb-•J'OUa opcutea ia
Ita approprhu !uqucncy band:
,.i' •
ci •
h • F(t) • .!.Fobcrc tbe nodal coatrol force <I.P Is
&F • 'A·~·- laci - lli:ph Then aobultutlos (1.1 int<> (1)
For tbc cue (A • rR • lli:p • 1: n;,· + ci + h , . [1/(l+lli:)l P(t)
aad tbo nodal ruponu h attooaated by tbo hctor 1/(1•() •b.ih tbo aodal
reqoirod.
The courJ 1oratloa conaidercd Ia [1-1<4] ••PI<>ya aa lDdlYidul aotaat<>r and naltiph fccdbact loopo t<> control caob blade. Thcao actnat<>U aad
plate h not ftqulrcd, RowoW'<rr, ooac applicatlona or indhldual-hhdo-control
cootrolHill th~ bhdn tbr0111b o coanotlonal owasb plato ao du~ribod In Suti<>o 9 aad in [15, 11].
'lllo followlq aocUoao 4oocrlbo tbo ded1a or a aystn co•trolUa, blade lhpplaa, ~oadi•l• hJ, aad toratoa .t,.a•lca, aad rotated tttotlllJ or tllo ayltta oa a aod•l rotor b tbo wlad tllaad. Tho coatr<>l laputo couldond arc
Yeloclty, aad dioplaceaeat, a11d h i a01.d touloa Yelocity. It h tben ab<>•n that lldhoptor JUt alhYiotioa, attlt11do ohbillutioa, Ylbration allcYiatioa, aad lP lal danpinJ au,aoahtloo ca11 be achhYcd aola1 tbo COIIYeotlo.lla) b.•llcoptor awaob. plat• !or aa M-bhdod totor wbero N>l, For N~3, all appllcatlou can be ach.hYed,
1, GUST ALLI!VIATJOM
Roforucea ll-41 duod.bo tbc applicatl<>a or IDC t<> bclicoptcr 1nst alhthtloa. The toedbact blade plteh cootr<>l ••• proportl<>ll&l t<> blade !hpj!lal U<loloutlon alld dhpb<!eaollt, I.e,,
.40 ..
-I[(~+ tll
'
A bl.>ct dhJU• or tho contrnl syst"'" h ohown In Fi1oro (1).
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Th~ aboTo teohnique p~ovidu all the bta ... atloD. reqD.ind to create the bendina hodb&ck dt,..h
(J
+'"i
1 ), ;, and It dulred, the riappiD.a tudbact d&,..h(ji
+a2~) and/ori.
overall aystto•, co.qlosod or a ou·voaotor control lint tho pitch •otlon of th" blade, •bleb h 0qnippod •lth three accehro•etors to provido tbo uqnircd recdbact slcuh •• do•cribcd abcu.
...
where G • accohrotloD. due to Jravity The iDtocrator tnn•h~ hnction h alvu by
l(o) · · -(a/3 + 112
Hote tl1a into&r&tor lo...-freqaoncy roll-nft of 3 ud/u., to avoid tho applleatlon of aa hllaitc d.c. I& ill to &Dy oteady-ot&u c.,.pouato in the
Fr.,. tho lnDcr-lcop block di&Jn• obowb ill l'iJbU (8), the eloud loop tunohr h~>ction H(o) fro. 3D to 1 !orr g 8, Q • 31,-4 ~•d/ue, w
1ta • l, abd 1: "3 Ia readily obtained [8. 91. tho couupondin1 h.ner-loop root locua II obown in l'i;bro {?).
Thea !ron tlno outer-loop block dhJra• ill Fi1nre (10), tha li,..1 cto . . d loop tnnohr tuactlon hon In to 1 ia obtianod. The corrupDndinJ onter-loop
ted~>otioa h boJ>dinl rooponu to I/(1+1:) • 0.2S of the orlJhlal nl01o, i.e., an attennatiDn o! 75'1> witbDnt oi&niUHnt cbanco in bendilll natnnl freqnency
Uatwhe bendlnJ rupDau. nd prco,..ably ito auDchted "e~Uul inertial vibratory sbear, n poatuhtod above.
In puetico, Duly cortoh ba . . onics of tho ve~H<:al vibration dne to blado bcadin1 can bo transaittod to the !llubJO by anN-bladed rotDr. Those ha . . oJ>ico can be cDatrolled usinJ biadc-aountcd acceloro•otera aa uaaora aDd a conventloaal o•a•h plato. u ducribod i1> SoctloD ?.
It abonld aloo be aoud t.h&t aappuaaloa of bhdo thpplq and fht•h• bendla1 rupouoes and tlleir corrupoodia& in-plano CortoiU forcoa will tend tD alleviate lll-phu •ibratioa aa a beaoticlal by-prodnct Df TOrtlcal vibutiDII allevhtlo11.
$ • LAG DAIIPINO ADGWENTATIO!<I
For ha da•PIDI &nJ•ntatioll, a Ur"1'0100tor control& tho pitch a011Ie
ot
tho blade wbou Ia& aceelont!Da 11 oonud by twg accelorOfODUU, and an lntesntDr yield• tho las velocity wbah i l hd bul:. thron1b a cOfOpoeutor to the blade pitch eoatrDI [7, 101. A blade !l&ppill& ¥CIDcitY ia thea JOIIOratcd whicb in tho prounco or blade conha &nile, rosulto in aa 111-ptana .,...,.,t dne to Corloll• !oren which oppoau la1 •Dtian aad h propDrtloul to h1A scrin of wind tunul tuto of tbh ay•U• ••• n.n ntiHzinJ wblte
nDiu ozcitatlon o,! blado pitch. Uo runlh are ahowa hi FIJnre (1-4) In tcnos of ha accchrotl.on "'•ani tude and phne u a fiiD<~tion Df pitch ncl.tation CuquJ>cy for the rOtDr at advance rattD 0.27.
inc:rnud. Tho incruu In h1 da•phl ratio dno to tho control oyot•• wao dotcnolnod to bo O.l7 at adnnco ratio 0.27. 'Ihh value h lncr"'cnt&l to the open IDop value of 0.37 d11e to boarinJ frict!Dn.
6. STALL l'LIII'IItl. SUPP.tESSIOH
l.elerencoo tl--41 ollowed that apprDprhte feedback to a positiDn coatrol
to lo...-froqnncy JIIH hpnU. Si•llar •etboda wore applied to alluiate tba violeat toniDul •Dtiou UIDchtod with Hall tlntur. At bi1b hlado an1 teo
of attack and ccrtaia reduced fuqnu.oho, urod,.,..,.h .,..eat ll.yoterool& cauou a aot bpnt o! our1y to blade torslDnal •ot!on, ao that a01y
•••11
blade oacillatioa J<Dws with ti•e. Suh a altuaUo" h typicalot
•i•phpitch. 0.. the adnnchs aldo, tho blade ezporhacea atrona poaitJvo da•phll at ID• ana leo of attacl:., bat nn the utrutiJ>I oicle thD cfUcthc da•phs caa to•poradty
buo••
n&&tiwe. had Ins tD the ooolllatlons deoDribod above.ncnrsiDn hto J>OIUho daapilla. O..o way to achleyo thh oad h tD pro~ ide pitcb-rate !oodbacl:. !roa the bhdo to the pitch coDtrol urrD {FI,,.re Ul.
'Iho dotallo Df thh CDooopt. it. l•phaeataUoa. aad tho ro""lts Df upcri•onto nti!lda1 It arc 1ivon In (S, 6].
Typical t n t runlts are 1hown 111 FlJaro• {16 aad 17) for an adnnce rati<> of O.Jl. Nato that tho ltall rtntter COIIpOnont h ot!eoti•ely anpprnud with lacuaalnJ toedback.
7, FLAPPING STA!Ill.IZATIOH AT BIGU ADVAHC2 RATIO
Sinco hhdo flap da•pinl a01d rcotorinJ [Drua can be controlled nsin1
me
tccllniqJ>u. tile hiJh-advanca-ratlo flappiaJ !notability or helicopter bladco duo to periodicityot
theu !oren caD bo olialaatcd. The ai•plut ••thod wonld bo to lnoroau tbo acaa 'f&lun of bhdc fhp damph>J a11d re•torill1 fol'<ln by too~llad.: Df blade flappin1 YOIDDity and dhplacc•ut t<> blade plt<>l11 c011trol aa dhcuaud b Sectioa 1. Dowevor. thh app~oach wanld not rodnce tba 1ar1• poriodic!ty Dl these CDrDos at blab ad,.anco ratio. A •oro aDpUsticatod co•trol tocbu.Jqu to coatrot tbia porloidlclty h doacribod llolo•,l.oforencu (11, 16] ducrlbo tbo runlta o! an iavutlJ&tioa lato •othodo of
me
coatrollor dnl1n for linur periodic •y•toao ntllhios an euoo•lon Dl •oder11 CDIItrol aetllad•. Trend• pnunt 111 tho ooloctioa of yarlons coot fnnctloao ara Dntllllod, and cloaod-toop controller reoult& 1rodomo.,•trated Cor t•o cuu: Hut, Dn an aaa!DI comp10ter simulation Df the rl1id ont-of-ptano rlappin1 dyoa•ic• of a alnJle rotor blado and oecond. on a •ode! helicopter rotDr In the •iud tnnnol, hDth Cor .. ariouo biJh lnels or ad .. aace ratio. It h ahown that •odal control n1i111 the IDC coocept 1o pDulblo over a 1•r1o ran1e or advaaco ratlDa with Daly a •Odcst ••oant DC eD•J•nt& tlooal powor nqoired.
Typical wlad tunnel toot uaalu are abown in F!anrco (18) aad (19) (or opon-aad el<>ud-loop cuea at an adTanco ratio
ot
1.-4. It II uo<> that periodic co11trol af rotor bhdo fhppU>J dyna•hs Is huiblo even for u:trene flight CDIIdlt!OilO•Rofouacu (11. 16) aloe coaula
on
uullont di1<:uuiou of tho ""lqno advaut1101 of ndnt blado-.oUDtod accolaroaohra u unaora ill dodsnint o bl&do "odal control oylt..,.8. STALL .I.LLI!VIATION ANII P£RroiUIANCE ENUANCEIII!NT
lr rotor Ioadill& h lncru.ud b tho foro and aft porUo111 of tba rutor dht and rodnud in tho Iaten! portlona, tho loodod rotrutin& bladu will be oporotlnJ at hl1hor aaaleo of yaw and hlahor pitch rcdnced-froqllonclu tha 11
porfonoa11co. S11ch a chUIJO 1a rotor loodb.J oaa be obtobod with tho bhdo pitch ti•" hhtoq
o},.,.,.
h. Fil""" {lG). 1'bo111h a coaplotoly adlitroq pitchof IP. lP, and 3P pitch h Ollflloyd [23].
Rohn""" [ll] c.o,.aidou ody opu.-toop L.phaoDtatJon of thh pttch tt•o b{Uoq, nbuqnnt opplicatlona
••1
invoh'o cloud-loop urbtlo• ofpitch .uoplit11do aad phuo b. occo .. du.co oUb • - • •noaro of blado atoll o11ut Tho pitch tl•o bht<>ry ob<»rn h Fl.,oro {lG) woo teaud on a •ode! rotor in the 11ind tonool. Applicatio11 or lP aad 3P C)'clic pitch oli•lutcd biJh !roQoucy blade 1&1 accoleratlou b"llnod to bo uaochted 11itb rotor blade au!!. Do11ovor, doe to blodo •.challical pitch ll.•lhtiorn, &l>batanthl blade at.ll waa 10ot o11conntond, a"d tborerore conohal.vo dc•orootution of tho oucceao
ot
lP 1r1d JP C)'Cll¢ pitch in alloviatliiJ IIOU o:r.trcmo rotor blade 1t1ll IIO&t nait tostict with luruacd •ode! blade pitch upabl.llty,PrclJ•Inory •ort baa indicated that thoro on aobatanthl l'"rfonoacce lccrc•octa to bo obtained hoa tbc lntrodoctlo" or appropdato hisbor hanoonic control to tho holicoptor rotor t<> rodnco bdacod dus by re-dhtribotlon of bhdo loadlnJ. Sic~• !Jtdh"ldaat-btado-colltrol h a '""""alhatioa of hlahor ha ... ollic control, ol•ilor boJtofita ca11 bo npocted hi thl.o apJllcatioJt,
Slllco It la pouiblo to •odtry rotor loadia1 dhtdbotlo11 u h s IDC techniquu u dourlbod abOTe. i t
••1
1>o poaal.ble to rodaco rota .. 11ol.u Iiana tons 110b1 theae toch..tqau.9. HQ.ICOPiU DmiVIDUAL-l!LADR~COHnOL USNG A CON\'l!NTIONJJ.. SYASII I'I..ATE Sncul l11portaat d)'•••lc phca-ru.
ot
the bollcoptor rntor occ11r at banoonica or rotor .. ototioul speocl:(1) Gast-hducod fhpplcJ, both qoaal.-study and at lP
{2.) Sha!t-..ootioll-illdllced fhpplnJ, both qoasi-otudy and at 11" {31 Airload-tndncod Yibutioc at NP and {N!'l)P
(S) Tilt-rotor "'uouvcdn& loado ot lP
Sections l , 3, ud 4 have shown that indlvidaol-bhd~-c<>lllrOI COli dlnlato it<:>.> {1) LO {3) above, S~etion S doaonstntcd tbo~ bbdo h i donphJ Cl" be n;•ontod us in& InC to suppress ltoas {4) aod (S).
It Is now sho•11 that l!IC eon h imph•ontcd throqsh • convcntlou1 S11asb ph•e to al\eviato ito11.s (1) to (5) r .... tl-blodod rotors'
The eontrol requiro~tont for tho 1>tb indivldul blade i&
n,.
couupontlio& c.>ntrol uq .. ;;r.,.ut for tho awaoh ph to la•Q • !l0 +
o
1c co•• + !l1c olaif + o1Uun& tho m&thcaatles
ot
]~hnonn•. P, 351, the COJtUol !&111 are02 g 0 nnlcos n " pN ± 11/2 (]ohnson•, P. 348)
.. here p g any lahacr
'Ib.o phyolcal slJdtlcollce of the o.bove oquatlono Ia that IBC of anN-bladed rotur haYinl a connntlonal ••nb plate Ia poaalbh !or thooe lDC tunctiou hvohinJ tho urotb (qnul-ateady). t t n t , pNth, and (pN±lltb bo..,onic& or r<>tor apud,
•·I·•
an•t al1ovhtio10 (p•O), attltode atabilhatl.on (p..O), vl.bntlon alhvhtioo (p•l), and auppreulon of air/JrOIIadand tilt-rotor aaullYerlna loads {p•G).
Note thll all lla ... o..tco o11d h JOUrol any arbitncy tlao hhtory ot control are acllievablo 111th a threo-bhded rotor ual.n1 a eonYntloool aw . . b plat•.
'Illc """"&tioos or hdlviduol blade unaor ol1o•lo rcqolrod to obtai11 the nub !'I& to colie~tho and cyclic pitch COIOponento provide a Clltorin& action oucb that only rbc desired hnoonica OP, lP, NP, and (N:!:t)P ro .. a!Jt after
•"""'•tlon, l.o., ao opocific ho .... onic oJ>alysls Ia rcqairod. lD additio,., so•e amootbh& of rondo• nnho in tbn dauh ••Y roaolt,
Sinee all ao)l;dna to done In the bladu, no tnno!e .. aotrlcco Cr"" J>aa-.. otatio& to rotatlnJ &)'SUD are uqnlred, thereto .. ., oo npdating or these motdcea h required, and no non~!inoarlty p~obhoo u n i t Cr..,. the
llnurhatlo10 reqoiud to obu1n tho tunahr aattlcu. Aloe, blodo shtc D<UilUmcnts allow tlahter nbiclc co,.t .. ol sincn rotor coJttrol cuo lood lunla&e .. uponn: thh had ohoald proYide 110re oftectlva Jnlt alloYiotion and penolt biJher control authority wltboat iadneia& rotor lnstabilltho than wo11ld be p011ible 11lthout rote .. auto hodbact.
allevi.•tion and attltndo atobilhotion of an N-bladod helicopter rotor:
(1) two fhtwiu accelcroDetcro po .. blade.
(l) a •uns of tun .. tlttiiiJ liJnoh ft..,. r<>UtiDI to non-rotatinJ
(3) s•aah plate actuotor bandwidths op to dhtnrbance froqnoncy, Tho followt..1 oqoip•eJtt Ia roqoirod to illph•e11t IBC for Yibutioo alhvbtl.o11 o! on If-bladed helicopter rotor:
{l) tour Clatwiu accoh .. oDctars po .. blade.
{l) o mo&Jta of tun . . ittl.aJ ala,.•h !ro• rotatina to non-rot& tin&
.,.st••·
(3) owuh plato actuator l>arod'llidtbs op to IN•llP,
The £ol1.,...ia1 oquip•ont Ia roqDirod to l:lopleaect IBC for soppnuioo of
air/1roond uoonanco and tl.lt-roto .. •noovorlnt losdo o£ ao 1+-bhdod
helicopter rotor:
(1) two Io111tu a .. coleroOictcrJ
P""
bhdo.(1) • mnna of tro10s•HtlnJ ois10ds !ro• rot&tloJ to no .. - .. ot.thl
(3) awnll plate actutor band11!dths op to dlotnrbonco frequency.
10, CONCl.USIO!'I
uceleroouteu ao ooaoou ••i:u pouil>le the COIItrol of tho Clapplag, fhhrioc bondina, !&a, and touionol •odoo of ncb bhdo indhldnatl,.. Thh ~ontrol technique i l oppll~•bh to bollcol'ter rotor lUll altevhtioll, attitude otabltiutlon, vibration allniotlon, lot dampln1 ""'"""tatlon, ohll fl•tttor onppreuioll, bhde flappinl atablliution ot hi1b advnco ratio, •tall alleviaHon, &lld perfo:n,.nco oncbancoaonL
For rntnrs b.., h i three bhdu, 1n7 orbitury pitch tiao hhtory coo be opplled touch blodo illdlviduaiJ,. uolns tbo connllt{ouot a· . . oh ph to. Rotors with 010re thon three bladeo roquiro hdlvidul oct<latOra for ncb blade for
"'I'Prouloll oC alrfarooad uoouuo ud tilt-rotor •a•oavodal load1 ) ou• be
1,
u .. ,
N.D., "A Shrplo s,.at- !or Ddlooptarladlvidui-Biad..-Coatrol Uoh.l llodal Doeaoopooltloll•,!!.!.!.!.!.!•
_!, 1, 11180.1.
U.•,
N.D. nd llcUIIlp, 1.11 .. Ir., 1A Si-;oh s,.ot- for Dolleopur bdiYldul-Biado-Colltrol a11d Ito Appllcatloa to Gaot .Uhvhtioo•, Proo, 'IWentrPiut AI..U. Stractaru, Sh.,.ctural Dnuatco, aad llat•rliU -~.Suttle, WA, Na,.uao.
3. R••· N.D. ao4 llcl:illlp, 1,11., Ir., •A Sbrph s,.otoa tor B•ltcophr fadiTidu.I-Dhdo-Coatrol utd Ito Appllc:atioa to Gtoot Alhviation•, Proc. 'n:lirtrSIHh AilS Allan• I Hati~tul Fonut, Wuhia1ton, D.C., Jb.y
xno.--4. D••• H.D. and llcUlllp, R,ll,, Ir., "A Siaph s,.ata• for Doliooptor In4iY!dui-Dlado-cltatr!tl oad Iu Application to Gut Alhviatloa•, Prac. Si:zth Ruropun Iotorc:raft Fe...,., Bdotol, tl.J:., Sopt . . bar 1910.
-'.
Do•, N.D. o11d Qaukonbaoh, T,l.,, •A Si•plo s,..t . . tor Bolicoptar Indhldul-Bia4o-Control aad Ito App!Jcatio" to Stoll FIBttar Sapprouioa", Proe. Snonth Enropun Rotorcntt Fonuo, Gu'llheb-Partenld.rc:hea, Fii:G, Sopto•bor J§n,6.
II•••
N.D. and Qaul:tnhoh, T,R,, •A Si-;ohs,..t ...
for Dalicoptor ladlvldul-Bhdo-Coctrol •ad I u AppHcatloa to Shll-bduod Vlbutioa Alluhtloa•, Proc, ADS Notional Spoc:hlhto' llutlna eo Bollo<!'Pter ~.Hartford, CT, Noy . . bor 11181.7. Boa, N.D., Behal, Bd1itto L .. ud lieU! Up, R.N., 7r., •A Sl•plo s,.or . . £or lloHcoptcr Iadhiduol-Dlad..-Colltrol and lto App!JcaUoa to La1 Bo•pl.11.1 Aa1•oatotloa•, Proe. l!iabtb l!.ll.ropoan Iotorcuft Fo.,.., Ab-on-Pronaco, Frnc•• Soptoabor 11112.
8. Ba•, H,D,, "lloltcoptor Iodil'idnai-Dlod..-Coatrol and Ito Applloatiooo•, Proc, 'IhirtrHiatb AilS Azonul Noticul Foraa, St. Lonh, 110, llay 1983.
9, U.a, N.D., "BoUcoptor IodiTtdaol-Dlado-Cootrol and lto.Appllutloao•, Proc. Ninth l!.ll.ropua Rototcutt Fo..,.., Strou, lhly, S•pto•btr 11183, 10, Do•, N.D., Doha!, Bri1itto L. ud llda11tp, 1:,11., Ir •• •Uollooptor Rotor
La, Doapina An1•••Uti011 'Ihrou11l Iadhldaal-Dhd..-Controt•, Vortlc:a, 7,
4, 111113. - - -
-11. llel:illlp, 11:.11., Ir., "Puiodio Control of tho IDC Dellooptor Rotor•, Proc. Tenth illlropua Rotouutt Foraa, The Del""• Notlr.orlaado, A!ll• 184, 11,
«•••
N.D., "Doltcophr Stall Alhviatto:a llolo1lndiTldn•I-Diade-Control", Proc'. Tenth ll<trnpu 11 Rotorerart Fonut, The HaJno, Nttllorhndo, ... 11184.
flG
+!C>\
fl
BLADE
Y-
ACCELEROMETER
i
0.295
17(~+1)
~+
2(014)5 +I
(55.6)2:
( 55.6)
{54,5J 2
PlTCHtSERVO
t
0.249
J
0.640 1
..2.._+!){~
+
2(0.69)5 +I)
((132)
(145)2:
(145)
I
POTENTIOMETER
FIG. 1
GustAlleviation Systen Block Diagram
GJ-5
U. Baa, K,D,, •llolioopt.r Attit>~de St.blliit&ttu UoiiiJ Iodbid,..l-Biadr CoatrcJ•, Proc. Tuth E~tropuo RotorcraCt Fa ... , Tho llaaao, Hethcrlaad•• An1. 1914.
U. B••• N.D., •Actin Ccatroh", JUT D.P Sepod.,. aD Bel!copter Toc:h .. olou. Cubrid••· IIA., Kov. 1984.
IS. Roa, N.D .. "llellcopur Gu•t Allnhtion, Attitado Stabilhatioo, an4 Vibrotion Alleviation ilala1 Iadlvldu.l-Diade-Coatrol 'IhrOOJh a ConveatlOUl Swo•h Plato•, Proc. Fortr:Flut ADS Aaanal Notional For,., Fort Worth, Tc1n, lla,. t98S.
16. llel:llilp. 11.11. Ir., "Periodic: Control of tlle lndi ... idnat-Db<!e-Co<ttrol Delicoptu Rotor•, VerUca,
2>
1, U8S,17. Do•, N.D •• "lleltcoptor Gaot AlhYhtioll, Attitude Stabiliutlon, and Vlbratloa Alhvatlon Uoia1 IBdividul-Btode-Colltrci 'Ihron1h o Convootionol S•oob Plate", Proc. E!enath Europun Rotorcutt For~~:a, London, D.(., Septcabcr 19U.
Rcporto or tbe VTOL Techno lou Laboratory. JIIT:
18. Hel"illlp. R.ll., Jr., "The Bu;,,. Tcotia& aad Evaluation of the lifT hdhid1111-Dlade-Coatrol Systc• u AppJUd to Guot Allovhtlon for lleticoptero•, V'lL Til: 196-1, Fobrury 1'180.
19. ltahnell&, II,A .. "All ... htlon or IJollcoptor P'u.uh&e-Induced Rotor Ullatnd,. Loodo tbroo1h Doterainiltic: Variation of tbe Iadivldnal Diode Pitch",
vn..
JR
196-1, lloy 1951.10. <hlachnbub, T.ll,, "Tcotin1 ond E•aluation o! a Stall-Flatter Suppruoion s,.ote• for llolieopur Rotoro Uoina Indlvidnai-Diodo-Coattol~,
vn..
Tit 196-3, Au1oot 1981.11. Dehal, [I.L,, "Dul.su and Tuths of a CoDtrol s,.oteD to Ineruoe tbo Lu DaOiplnJ of a Bellcoptet Bia4e", VU. Tit 196-4, Aa1not 1961.
11. Da•, N.D .. "A Prcli•lury Note OD the Appthation of Individual-Blade~ Coatrol to Vertical Vibretloo Allovlatlco", VU.
m
196-S, October11181. 23. Cole, C., The l!lutronlc S•ub Plate !or lndiY:Idooi-Dlade-C!tatrol", V1t.m
196-6, Narch 1984.14. llel"illlp., R.JI., Ic., "Periodic Control or the IDC lloUcopter Rotor", V"It.
Tit 195-1. Ansu.n 1984.
15. Uoa. N.D., "Ind:lvi<luoi-Dla4e-Coattol Rcooorch in tbe JilT VtnL Tecbnolos,. Labcntory 1917-1985",
vn..
TR 196-a, lune 11186,Pate!lto:
16. Do•, N.D., "Helicopter Indivld111l Dlado Ccntrol s,.atca", U.S. Potent No. 4,H9, Hl, Ho,. 28, 1985,
0, B
SUPERHARMONIC
a
KEYo
CIO. B
a
SYM
_,_
~a
D
o.
•
•
a
v
• ••
..."·"
•
• • ••
•
t
•
•
1.2
dl.
0.2
•
X
~
v
o.
0.8
EXCITATION FREQUENCY
Cl B. B
~...
•••
dl.
0.2
t
f
i
~
'J
••
v
'
SUBHARHONIC
~~···r
i
t
Jt
... 0.2
t
dl. ••
o.
0.2
0.4
•••
"'
I
!l
GAIN EFFECT ON FLAPPING
MU•.2
FIG.
SUPERHARMONIC
•••
KEYo
•
SYM
3:uB.B
... 8.4
ca. "·
2
..
•
•
!
a
J
~
a
A
•
1
a.L---+--~~
•••
,!t:;ClB. 6'
"·"'
ca.
e.
2
EXCITATION FREQUENCY
a
{
a
I
a
f
a
l
a
l
a.L---~---:.o"•-•l
' 8 . 2
SUBHIIRMONIC
0
v
•
A
~
a.
L---·--~~~~i--~IL-~1~
B.
0.2
9.4
B.B
<.l
I
Q
GAIN EFFECT ON FLAPPING
MU•.4
...L
••
•• 4
•••
1.2
FIG. 3 Effect of Feedback Gilin on Flap Angle Response to Gust
(IJ"'0.4)
3.5
..
"'
3.0
.
of"K" 0.5
w
1-w
---::;:
..
l r2.5~
-cc
>-!::
-' 2.0
1---
,(K"O
"'
---;:!
--
--...
V>
I
1.5
u
1-a:
'
z
1.0
"'
~
0..
0.5~
KA=KR=Kp=K
::;:
..
y"8
Cl
aL---L---~----~----~
0
0.1
0.2
0.3
0.4
ADVANCE RATIO
fl-o
FIG. 5 Rotor Damping-in-Pitch Stability PdNmeter Versus Advance Ratio
63-G
"'
"'
w
1-w
::;:
..
"'
..
0..
>-
1--'
"'
..
1-V>
"'
u
..
1-!;_:(
'
"-0
'
w
-'
"'
z
..
T
\
\
\:1--
IC.G.
_j
0
Th
ta-{3
1cl
\f-
h
{a-{3
1
c)
FJG. 4 Geom~>try for LongitudinJl Stability Analysis
0.6
0.4
0.2
0
-0.2
-0.4
0
KA=KR=Kp=K
Y"8
0.1
0.2
0.3
0.4
ADVANCE RATIO
fLo_
FIG.
7Bhde Fhtwise Inertia Forces
600
500
+
K= 3
400
X
200
100
-3!coo,----=2-!o5o,--_-=2"oo~--lc!5-=o--
c!lo"'o,---"""5'--o---o!o 0
REAL
FIG, 9
Inner loop Root Locus (Vibration System)
+"
600
500
400
(!)300
<I
/::;;;
200
100
-4o~o=---=-3-J,oo-=---:_2-,~o..,o----=~oi:o---"'o
0
REAL
FIG. 11
Outer Loop Root Locus (Vibration System)
63-7
,,
BLADE
DYHA!HCS
SERVO
DYHAHICS
GAUl
ACCELER-OMETERS
FIG. 8
Inner Loop 81ocl: Dia9ram Yleldin9 H(s) {Vibration System)
HINER LOOP DYNAMICS
GAIH
ACCELER·
m-!ETERS
BITEGRATOR
FIG. 10 Outer Loop Block Diagram (Vibration System)
;::
-'
a
>
'
~-'
a
<:
"
<
"'
Fig. 12
TIP
ACCEL, VARIOUS FEEDBACK (14HZ)
2. 5
-~-~-r
T
I
I
2.
:I·
...L
l.S
75:.':Open
~opAttenuation
Predicted
for K=3
1.
I~
-t:.,~,:J
'I
l~h~~l
.
'
I
j
(
I
:1!~
.~,
••
30.
40.
so.
•••
70 •
! ,
•
!
••
FREQ (HZ)
Open
and Closed loop Tip Accelerometer Response
to White Noise Pitch Input in Hover
ACTUATOR
FLAPPING
DYNAMICS
LAG
DYNAMICS
COMPENSATOR
INTEGRATOR
PI=
M300{1+j)
Pz" -12.1 +82.57j
wl
z28.74
rd/~WITH
RQLL~OFFFREQUENCY
SCALE
FACTOR
FIG. 13 Block Diagram of the System with Compensator
-0-..-<59-<-1
+ _+
-SERVO MOTOR
sooo[(T§s)
2
+
1]
(~+1) (~-l)(f,-1)
RATE
PITCH RATE
AMPLIFIER
POTENTIOMETER
Ke
INTEGRATOR
4. 0s
' - - - \
(3~0
+I)'
LINKAGE
AND GEAR
p"-.057+ 2201 FOR
SJ.=O
BLADE
0.972
[(,;sl'+,]
riG. IS Stall Flutter Suppression Systt'l:l Block Diagram
8
63-0
LAG ACCELERATION
DUE TO PITCH
p.=0.27, KR=0.3
"'
UJ 0 ~ UJ"'
<( Ia.
20
- - - . . ,
I
I
----~---,
~I
- - - - 1 - - - 1
j
-Open Loopj
o
Closed Loop-40ko---,~---~,
LOG
FREQ (RAD/S)
180
~-
-I
-
-=I
90
-"
=
-;
==-I--
=I=
-
-1
0
=I
I
-=~=
-I
-90
-1
-
1-2
LOG
FREQ (RAOIS)
FIG. 14 Experimental Results, p.-=0.27, .U=37.7rod/s.
Pitch
8
to Accelerometer Difference Signal
I/2(R-el!;"
PITCH ACCELERATION, KP•.02
e.
Stall Flutter
••
"'
~••
.J 0>
-4.
-e.
:!--::r::-::+-:-7:::-::'-:-::'-:::--:t-:-::'
0,
0.1 111.2 111.3
111.4
111.5
111.6
0.7
TIME <SEC>
FFT OF ACCELERATION, KP•.l112
3.
2.
1.
••
-1-LlL.._L...W,,.._,.l.Ll\ll.LU...,.~....,...
-':'1~111.
10.
213.
30.
4111.
5111.
8111.
FREC <HZ)
F!G.l6 Low Fe(!dback Mechanical Spring Test, fl"' 6.1
fl:,
~ r
-'
0>
~Ci
0>
8.
4.
..
-4.
3.
2.
1.
PITCH ACCELERATION,
KP~.26Ll L2 e.3 L4
~.5L6
~.7TIME
CSEC>
FFT OF ACCELERATION,
KP~.26·-~~~u4~L4~~~~~~
B.
lB.
20,
3B.
4~.SB.
6B.
FREQ <HZ)
FIG. 17 lliqh Feedback Mechanical Spring Test, n,. 6.1 II~, 1J "' O. 33
1-z
w
(Ju.
u.
w
0
(J"'
z
a:
::E
<(0
Cl. <(...J
1.00
0.75
0.50
-0.25
Open Loop
' '
\
\
"
'---Closed Loop
lL-0.50
-0.75
- 1.000';---,L---.,.12"
AZIMUTH (RAD)
FIG, 19
Experi~rentalRotor Flap DaJ!I!Iing Coefficient
Ill
z 1.4)
63-~
2.00
1-z
w
(J1.50
u.
u.
w
1.25
0
(J"'
z
0::
1.00
a.
<f)"'
z
0.75
0::
a.
<(0,50
...J
u.
0.25
0.000
/"
,_/
\
\
"
,_
AZIMUTH (RAD)
Closed Loop
/,--...
Open Loop
2"ff
FIG. 18
Experiment~]Rotor Flapping Spring Coefficient
(IJz 1,4)
2or---r-~--,---.--,---.--~--, ~ ~
~
16 0 ~ 0'
~~"
-'
0z
4•
8
u r ~ ~ 0 4 4-'
mBLADE AZIMUTH ANGLE
