Document
......... , _ : . - : , #.., i I
, - ! NASA Technic a l Me mo r a n d u m 86440
.._ USAAVSCOM T echni ca lMemor a ndum 85 -B- 5
AEROELASTIC MODELHELICOPTER ROTOR TESTING
INTHELANGLEY TDT
(NA_-T M -8o_0} A_a OELA STI C M ODE L N86-| 1 523 H _L - ,.OPYZR _O_O_ IEZ T ING iN _H£ LANGL E Y TDT (NASA ) 1 9 p HC AO2 / M F A0 I CSCL 20K Uacla s G3 / 39 2 " J _7 2
WAYNER, MANTAY , WILLIAM T, YEAGER , ,JR,, i
} -} M-N_IL HAMOUDA, MA J ,ROBERT G, CRAMER , J R,, ,
t '
ANDCHESTER W, LANGSTON _-i
f
JUNE1985
NAS A
Naltonal Aeronauti c sand Space Admm0stral,on _.
,{ LangleyResearchCen t er , m , i ' _ ABS T R A C T I s t h e u s e o f Fre o n-121a s a te s t ne d i um , w h i ch , grea t lyal ds in the scaling of models for Wln d -t unn e l te s ti ng of a p_op e rl y s cal ed a e r oel a s tict es ting. M os t model rotor tests aeroela s ticmo d e l he l lc o pterr o t o r I s con du c t e d in the TDT u tilize the Aeroe l a s t l c c o n s i d ere d a nece ss aryp h a s e I n t h e d e s ign R o t o r Experimenta l Sy s tem (ARES). The main d evel op me n t o f new o r e x l s tl n q r oto r s y s tem s , c_one n t o f t h e ARES i s a aenerlc rot o l te s t F o r t his re ason ,exten s ivete s tl nq o f be d for mea su ring r o tor l o a ds a nd perf o rmance aer o e l a s tlca ll y s c a le d m od e l r oto r s i s d o ne i n d ata, aer o mecha n lca ls tabilitydata, a nd t h e Tra nso nicDynami cs T unn el (T D T) located at vibration d ata. Thi s paper will pre s ent so me • the NASA L a ngle y Res e archC en ter. A u nl oue detai ls o n the T DT and discuss the benefitsof capability of t h i s f a cility,which e n able s us lnq Freon-!2 a s a te s t me d ium. T he mo d el and pr op er dynamic s calin g , i s the u s e o f Fre o n a s a sso ciate d in s trumentat i on that c o mpri s e the a t est me d i u m. T h e p aper pre s e n t s a ARE S , a s w ell as s o me so ftware us e d i n d ata d e sc ripti o n o f t h e TD T an d a di s c uss ionof the acoui s ltlonan d analy s i s ,will al s o be b enefit s of us ing Fre o n a s a t e s t me d ium. A d e s cri b e d . Example s of s ome of t h e m od el d e s cripti o n o f the m o del te s t be d u s e d , t h e aer n e l astlcrotor te s t s con d uctedrecently in A e r o ela s ticRo to r Experlmenta lS y s tem ( ARES), t h e TDT i s includedt o illustratet h e I i s al s o _rovldeda nd exa_le s of recent rotor techni q ue s u s e d to a d dre ss u n ique problems an d te s t s are cited t o ill us tratet h e a d vant a ge s r ese arch o pp o rtunitie s .
and ca p abilitie s of aeroe l a s t J cme d e l rot o r te st i ng In t h e TD T . T hl s p aper d emo ns trate s AeroelasticTesting I t h e im po rt a nceof pr o per d ynamic s caling in i d e n tifyinga nd so lvin g r o torcraftaeroela s tic General pr o bl e m s ,a nd affirm s t h e l_ o rtance o f !
a e r oelas tl c testi n g o f mod e l r o t o r sys tem s i n T he re s p o n s e o f either a full -s cale o r th e de s lan of a d vance d r o t o r sy s tem s , mo del r o t o r blade i s influenced by a e r od ynamic, ela s tic, inertial,and gravitationalloads 1 IN TRODUCTION acting o n t h e blade s ( ref. 5-6). For a model rotor bla d e to be a d y n amically s cale d ver s ion Hi s t o rically,the helic o pterind us try h a s of a full- s calerotor bla d e, the rel a tive not f e l le d o n wln d -tunnelte s tin g o f mannitudesof t h e s e four force s s no uld he the aer o elastlcm od el s a s m u c h as h a s t h e s ame between t h e m od el and full- s calebla d e.
fixe d -wingindu s try _,uf. _). The reaso n for T h is is usually accomplishe d through the u s e of thi s l ack o f te s tin ah a s been t h at n ew rotor ap o ropriaten o n - dlmen s ional s imi l arity ; de s ig ns h ave u s ual l y evolved from exi s ting parameter s .
d e s i g n s . Th e new rot o r d e sl q n susu a ll y h a d i aeroelastlc c haracteri s tic s that were The succe s s of the dynamic simu l ation ; r e a s onablypre d ictedby extrap o lations o f e f fort d epen ds on the ratio of the model i exi s tingdata, and thus the nee d for non- dl mensional similarityparameter s to the ; win d -tun n el te s tingwa s reduced. Win d -tunne l s ame full-scaleparameter s bein a u nity. In te s tin g t h at wa s co ndu c te d was u s ually do ne In a c tual us ag e , particularlywhe n t esting in air, alr. T e s t s done at full-scalehave been it i s v irtuallyim p o ss ih l e fo r t h e se ratios t o ( subject to tunnel speed re s triction s ,While all have a value of unity. For thi s rea s on, testin q re d uce d s _ze mode ls in alr ha s not attempt s are made to match the m os t importa n t re s u l tedi n a s im ul taneous mat c hi n g o f parameters, d ependin o o n the test re s u l t s a d vancln a bla d e tip Mac h num be r, a d vance ratio, desired. Model a d vance ratio and Lock num b er an d Reyno ld _ n u mber, are u s uallymatc h e d to fu l l s cale va l u es to i simulatebasic blade relat i ve velocitie s with
I
Rapi d chan o es in rotorcrafttechnolo q y re s pect to th c te st n e d ium. T h ree a d ditional h ave led to the d evelopmentof new rotor non- d imenslonal Darameter s u s ually c o n s i d ered s y s tem ss uc h a s hl n qe lessand b e arln nl e ss h u b are Mach nu mber, Froud e number, and Reynol ds _ de s l o n % a nd b lad es tailore d to pro duc e number. Sin c e r o tc_ _ip s needs are ge ne ral l y s pecificd y namic characteri s tic s . T h e s e unl au e In the near-sonic r ange, dunlicatlngMach d e s i a n s have pr o vided t h e imp e tu s to ad dre ss number can h e important. Te s tina of the problem s of rotor s y s tem l o ad s , s tability, aeromec h anlcalin s tabi l itie s involve s coup ' _in o and vibration s durln a the de s ign pha s e rather between blade moti o n s and b o d y d e a r e e s of- than provi d e "fix es " t o pr ob lem s a s they occur freedom,making gravity effect s important,an d durin g d evelopment. Th e se desi q n s o Frou d e number s s hould be matc h ed. Rotor con s i d erati o n s can b e st he a d dre ss edby performancete s ting, involvingairfoil wind - t u nneltestinq, at repre s entativefli g ht e valuation,makes Reynold s number matchlnn c o n d ition s ,of a pr o perly scale d aer o ela s tlc important. In addition,ela s tic an d mass • mo de l. Add iti o nally,t he r e ar e op p o rt un itie s s im u lationr e quire sdu plIcatln a rntati n Q I n mo d e l te s tln a t o thoroughlyinve s tigate natural fre a uencle s on a per-rev ba s i s . T h i s po tentialimprov e ment s t o rotor s y s t e m s t h rou gh woul d be n e c ess aryfor bla d e load s and • aer o e l a s tlc d e s ign modifications ( ref. 2- 4 ). vlhratl ons tu d ie s .
E x t ens i ve t es ttn a o f a er oelas t Jc a ll y sc a led me d e l helicop t e r r oto r s is done i n t he v aria bl e densi ty T ra nson i c D y n a m ics Tunn e l (T D T) loc ate d a t t h e NASAL a n q le y Re s earc h C en t e r. A un iq ue capa b ility o f tht s facility ZFre o n-12: Regi s tere d trademark o f E . I. du Po nt de _ le m o ur s an d C o ., Inc.
A "i oo Scale Model Testtnq A greed w ell with ful l -scal e r oto r da ta (Fig u re s 2-3) e ven at t h e l ow e r values o f m odel Re y nolds Th e us e o f sc a l e rot or m o d el s t o m o d e l num b e r s . The exact m a t c hin g o f f ull-scale a eroel a sttc events can be Jus t ifi e d through rotor Re y n o lds nu mb e r w as a cco m plis he d b y c o nsi de rati on s of cost, s afet y , a nd e a se of utili zin g the wi de cho r d m odel r otor, b ut wit h m aking d e sig n c han g e s . _h e n c o mp a re d t o a c co mpa n y ing m ts - mat ch e s in ro t o r so li dit y a nd ful l - s cale _ig ht s t ud i es , mo del te st s al so d y n ami c s ca ling . Th e c _tle d pe rf o rma nce h a ve t he a dv an ta g e o f co n t r o l of t he b a s i c resu lts for t he fu ll - s c al e a nd m ode l -sca l e a e r oe la stlc p aram e t ers a nd test cond i tio n s ro t o r s t s sho wn i n F ig u r e 4. R e ql on B o f ( r ef . 6 ) . Fi g u r e 4 il l u st r at es t he e xpecte d pe rf o r p wl nce t t r e n d wt t h de cr e as ing R eyn o l ds n u m ber f o r t h e The design of a scale m odel r o t or wh i ch w i de cho r d b la de, t . e.. m o re t o rq ue re q ui r ed a t s im u l ta ne o u s l y m atc he s a ll th e f ull-sc a l e a g iven r oto r ta sk. The unexpected r e sul t o f sim ila r it y para me te r s ts be y ond t he curr e nt th e se tests is Illust r at ed b y R e g i on A o f s tat e o f th e art , b u t f o r c e rtai n cop W_tnati o n s Ftq ur e 4 w hic h shows that b e tt e r mode l o f m o d el design a nd t e st e nviron m e nt t h e Jo b p erf ormanc e co r rel a t i on w i th full-sc a le values b e c o m es e r i c h less di f f i c u l t . T h e st r i at ion was a c hi ev ed wi t h a d y n a m ic a lly sca l e d rotor of t a sk i s ma de even mor e tr ac t ab l e i f t he the cor r ec t so li d ity t han with a r o t o r wh i ch a e r od y na m ic t es t m ed i u m can be t a il o re d , mat ched Re y no l ds n umbe r bu t whi ch was vb o t dy na m i c a l l y s cal ed .
Test MedtumConstderattons for Aeroelasttc )est l n _ The d i s a dv a n ta ges o f t he use of Freon-12 I a s a t es t m e d i u m ar e chie f ly cos t a nd t i m e T he ca p ability t o ad j ust th e t e st m ed i u m b ec ause o f pu mpt nq and s a f e t y c o ns i d e ra t i o n s.
for aer o ela s ttc mo de l s t ud ie s is g reatl y Al s o , the r atio o f s p e cific hea t s t s l ess f o r e nh a n c ed b y u se of a hea _ g as s u ch as Fr e on - I 2 th an f o r air a nd th i s would t_a ct th e !
F re o n - I2. Th e or op e rtl e s o f thl s ga s , li s te d e nerg y and c o m p r e ss lb;lltyr e lat io ns h ip so f h in T able I, enable s a m od el s cale r o tor t o Fre o n; h owever, It ha s been do cumente d (ref. 8) a ch ie v e larg e Re y n ol ds nu mbers, and a b ett e r that b e low Ma ch 1 . 4 t h e accuracy o f d at a ma tc h o f Fr oude nu m be r and M ach nu mb e r , all at o b t a i ned i n a F r e o n a tm o sp h e r e t s v e r y a l o w e r rot o r r p m tha n t h e sa me s t ze mode l i n accep t a bl e .
a ir. Sp ecific ally, for a I /5 -_I z e r o t o r m od e l, chosen t o si m u l ta n e ou s l y m at c h F r ou de and M a ch Thus, t h e b e ne fi t s o f F re on -l; f o r the nu m b er, T able II q u a n tifi es h ow clos ely t h e te s ti n g o f a e r oe l as tlcr o t o r m ode l s are F reo n -1 2 sc a l e d r o t o r mat c hes f ull - s ca le c ons i d ered s ig n ifi c ant. In a dd ition, t h e va lu e s , c a pab ilit y t o a c curat e ly s im ul ate r o t o r i dyn a mi c s a pp e a r s to b e as im po rta n ta I The adv anta g e s f o r m od e l cons tr u c ti o n, c h ara c teri s tici n m od el te s tlnq a s the e x ten d e d op erati on, and op portu ni t i e s for d i rec t Rey nol d s num b er c ap abi l ityprovi d e d by Freon. _- ) re s earchapplicati o n s aff o r d ed by a Freon-1 2 Se c t i onso f t h is p ap e r w il l ill u strate t h e , ) te st m ed ium are p er h ap s more subtle, b ut diver s e ra n ge of te s t applic a tionswhic h h ave equally attractive. F i Qure J illu s trate s t he u s e d t h e s e c h aracteri s tic so f F re o n-1 2 t o r edu ct io n in mo del power r eq u ire dt o match tip a d v a n t a ge.
Mac h nu mb e r a nd a d vance r a tio, p. A d ire c t b e n efit of thi s t o vi b rat i onan d l oa ds Test Facilities mea su r e me n t i s t he poss i bi lit y o f u s i n g qu iet belt- d rlv e ntr a n s m iss i ons rather t han Genera l c o nventi o nalgearln q . M od el con s tructi o nf o r rot o r o pertt f on i n Freon-12 i s als o e a s e d T h e faci l itycho s en for s cale mo de l rot o r ( Figur_11 t h r ouah l ow e r lo a ds a n d t he t es tingc a n p la y a n i m p or ta n tr o le i n mat c hi ng - a 11o wa n ce o f h ea v i e r s tr uc t u ral des l ons t ha n a e r oel a s tl cp arameter s . Tunnel cha ra c teri s tic s th o se o f an a_r - scaledmo d el a s sho wn in T abl e s uch a s free- s treamvelocity rang e , wall II. R es earc h applic a ti on sr e q uire lo w e r time effect s , maxim u m mo d e l r o t o r s ize a ll o wa bl e, s ca l e s in F r eo n-1 2 . T h l s I s a benefit to b o t h a nd test me d i u m capabilitie s wl ll determinet h e data analysi s and reaulre d c o ntro l in p u ts , su c h p o te n tia l f o r aeroel as tlct es ting. Many a s us e d i n a c t i v e c o n t ral a p pli c ati o n s , faci l it i e s a r e c o mpat i blew i t h exis t i ng a n d plan n e d rotor te s t b ed s , b u t very few offer the Re s earch s tu d ie s have b ee n c o n du cte dt o rang e of ca pab lll t T eso f the LanQley Tran so n i c de te r mi n e t h e ( u ltah il l t y o f F r e on - 12 as a tes t D y n amic s Tun nel ( T UT). S in c e t he maj o rity o f me d ium for a m od e l rotor (ref. 7). T hese th ls p a p er d e s cr i b e s te s tl n n experi e n c e s i n the s tu d i e s al s o uti l i z e d th e F reo n atm osp her e t o TD T to i ll u s tratete ch ni q u e s an d aer oel a s tlc , p r o v i de parametr i c var i at io ns in r ot o r phen o mena, a d e s cri p tion o f t h at f a cl l ity is in ae r od yn a mic s . Th i s w a s a rc o m p l tshed b y o r d er .
sub j e ct ing a 1 / 5-s i ze d y n a m ica ll y s imilar h e lico p t e r rotor in F r eo n -12, t o th e sa me tasks Chara cteristics of the TDT l as a f ull-siz e hel ico p ter ro t o r t es t e d i n ai r .
R e y no l ds nu mber v a ri a ti ons were a chie ved The L a n gl e y Tra nson icDy n amic s Tu n n el w as t h r ou gh c o ntrolle d F reon-1 2 d en s ity c h ange s a nd d e slg ne d t o s ati s fy the nee d f o r a tran s onic t h e i n t r o d u c ti o n o f a wide c h or d m o d e l r o t o r f a c i l i ty c a pahl e o f te s tin g d y na m i c mo del s o f a w hic h w as not d y n a mi c all y s c a le d , st z e large e no u o h to a l low s i mu l a t i o n o f i i mpo rtant s truct u ral p r o p e rti eso f air c raft. A ) In t h e a re a o f In te g r a t e d r o t o r s c he mat ic of t he T D T i s sho w n in F ig u re 5 . Th e p erf o rma nc e,t h e dyna ml c al l y scaled m ode l r o t o r T OT I s a con tl n u ous -fl o wt u nne l with a slo tted p r ov i ded da t a tre nds and m_ gn lt ud e s w h i ch 2 t es t sec ti on a nd i s cap a b le of ope r a ti o n u p t o _ ° t _L , I Mach 1.2 at sta g nati o n p,' es su r es up t o I atm. hi n ge less . T he ARES m od el has a streamlined T h e se t unnel l imit s o n Ma ch nu m be r a nd h e lic op ter f u selageshape enc I osinathe r o t o r s ta a nation p r essu r e hav e all ow e d r o t o r te s tln a c o ntr o ls a nd dr ive s y s t e m. T h e ARES mo del t o be do ne a t c o mbinatio ns of adva n cln a tlp rotor s y s tem i s powere d b y a water cooled Mach number s and Reynolds numbers as S h ow n i n v aria b le fre qu ency sy nchr o n o u_motor rated at Fi g ure 6 . The t u n n el te s t section Is 16 feet 47 HP o u tput at 12,000 r n m. The motor d rives s q u are wit h cr o ppe d corner s an d ha s a the r o tor sh aft t h ro u g h a belt-driv e ntw o - s tone cros s - s ectiona l area of 248 sq uare fee t . T h e s pee d re du cti o n s )stem. The ARES model rotor • s l z e o f the te s t s e c ti on ea s i l y acc o mm o dat e s c on tr o l sy s tem a n ( i r o t o r sh aft anale of attack r o tor mo d el s up t o 10 feet in d iameter. A are remotelycontr o lle d . T h e m o del rot o r shaft s im ul ated_st f ie ld may be ap p lied to the te s t a n gle o f at t ack is varie d by an electrically s ection flow in the f o rm o f a si nus ol d al contr o ll ed hy d raulicactuator. Rla d e os cillation o f t h e fl o w d irecti o n. Thi s c o llectivep : tc k an d lateral an d lonoitudinal o s cillationg us t s ignatureis ge n erate d by an cyclic pitch are inp u t to t h e r o t o r throuoh th e arran g ementof vane s on either s i d e of the s wa s hplate. The swa s hplateis moved hy three entrance se cti o n (F ig u re 7 ). Vane amDlltu d e h y d ra ul i c actuator s . T h is arran a ementis and fre que ncyi s v a r lab l ea nd the tw o p a ir s ma y p a rticularly us ef ul fo r e x citin a the r o tor be o perated i n or o u t o f p h a s e to pro v i d e a s y s tem d urin g inv es tigati o nsinvolvinnrotor s ymmetric o r a n ti s ymmetrlcgu s t fiel d . T u nne l aer o mechanlcal s ta b i l ltyc h aracteristics.
wall correcti o n sb a sed o n re fe rence9 are i avallab l ef o r d ata c o rrectio n . At l ow a nd ARES Instrumentation mode r ate a dv ance ratios, co rrecti o n s t o t h e tip / path p l ane a n q l e o f attack a r e s mall a s s ho wn I ns tr u mentation o n the A R ES model all o ws in T able Ill. A mor e de taile d des cription o f co n tinuo us mea su r e ment s and d i s play s of mo d el ' t h e TD T may he f ou n d i n referenceI0. co n tr o l s etting s ,r o tor f o rc es an d mome n ts , blade l o ads, and pitch link load s . The ARES in a dd ition to t h e TDT te s t s ection, a n m od el rotor s haft pitch attitu d e is measured by area i s al s o a v allahlefor hover te s t_n o and an acceler o meter, and r o tor c o ntr o l p o sitions " mo de l b u il du p a n d ch e c ko u t. T hi s area i s kn own are mea su red by li n ear p o tentiometersc o nnected a s t h e H el ic op terHo v er Fa c i l ity ( HHF ) an d i s to t h e s washp l ate. For the teete r in a hu h , locate d in a hu ildingadjacent to the TDT. T h e rotor flapping i s mea s ured h y a rotary HHF is a hiah-b a yro o m w i th t h e mo de l pote n tlometer. For th e arti c u l ate d a n d ,, te s t-stan d en c lo s edby co ar s e-me shs creen h ln g el e ss hu b s , h lade flap an d laa p os ition is , 30 ft . x 30 ft. x 20 ft. hiqn. The m o de l i s mea su redas follow s : t h e artic u lated h u h c,_es mo un te d on t h e t es t s ta nd s uc h t h at t he r o t o r r o tary potentl o metersmounte d o n the hub and ) is appr o ximately15 feet ab o ve the floor. The geared to the bla d e cuff; the hin a ele ssh uh HH F h a s it s own h y d ra u lic pu mp t o sup ply u s e s s train oage s mo u nted on the appropriate I pre ss ure f o r o peratingthe m o del control flexure s . The accuracy for these an a ular s y s tem. T he mot o r-generator s et u s e d to run measurementsi s estimate d t o b e wit h in +0.2_ i i th e m ode l d riv e s y s tem in t h e T D T i s also u sed d eg r ees . R o t o r sh aft s p eed i s d e t e rmined h v a to operate t h e model in t h e HHF. magnetic sensor. The rotatlnqblade data are _ In s trumentation, other than that mounte d on the transferredthrough a 30-c h annel slip-rin a mo d el I s als o c ommo n b etween the TD T a nd HHF. a ss emb l y. R o t o r f o r ce s a nd m o me n ts are sen s ed _ At t h e pr esen t time, the d ata re co r d l nq sy s tem by a s ix-c o mp o nent s traln-ga a ebalance m o unted i i n t h e H HF con si s t s o f a 1 4 -cha n ne l a n a l og ta o e be lo w t h e p yl o n and drive s y s t e m. Th e b a l ance recor d er. Data re d uctioni s d one on the TDT i s fixed wit h re s pect to t h e r o tor sh aft an d :omputer s y s tem, p itc h e s with the fu s elage. The balance _ utilizedby the ARES model wa s d esigne d to The TDT i s equipp e dwit h a data provi d e mea s urementerror s of o ne percent or ac au lsltlon s y s tem t h at c an ac q u ire lar a e l e ss . T he entire f o rce measurement s y s tem, o f _ amount s o f dynamic data ov er a w id e _ren ue ncy c o ur s e, co ntain s o t h er e rr o r so ur ces . Ba s ed on ran q e. Thi s s y s tem ha s t h e capa b i l ityof replicate dd ata point s , the re p eatibi l ityof provi d ingreal-time,interactive d ata ARES ba l ance data for con s tant s haft ang l e of reduction,analysis,an d d i s play as we ll a s attack, control ang l es and advance rati o ha s providln q the capa b ility for on- l lne monit o rino been e s timate d to be typica l lywithin the an d contro l of a wi de variety of analoq fo ll owinglimit s : in s trumentation. T h e data acaui s ltlonsy s tem con s i s t s of an ana l o a front en d t h at can CL / O + .0010 typical l yproce ss u p t o 50 channe ls of data, a CD / O _ .00025 mu l tl-channelanaloq-to-di o lta l s ub s ystemthat CQ / O _ .00015 " c an pr ocess u p t o 5 0 ,000 samples of d ata per second , a nd a d ig i tal c o mp u t e r wlth g ra ph ic s F us elag e for ces a nd m o ment s are no t s ens e d h y ca p abl l lty. A more d etai l e dd e s cr i ption o f the the balance.
• T D T data ac quis ition sy stem I s aiven in refere n ce11. A dd iti o nal in s trumentation, other than that mounted on the ARES mo d e l , i s us e d in t he A eroelastlcRotor ExperimentalSystem d ata ac q u is it i on p roce ss . T h i s instrumentatio n i s mounte d in four cabinet s ( F ig u r eq ) that are R o tary-wlngte s t s con d ucte d i n the Lang l ey po rtab le and are u s ed wit h the ARES model in T DT u s u all y u ti l iz e t h e Aeroe l a st lcRot o r both t he TDT an d the HH F , O nly t he prlmarv E xp e r i mentalSy s t e m (ARES). T he mo de l p art o f feature s of each o f the s e i ns tr u mentation the ARES ! shown I r F(_re B. Tes t s may he cabinetswill be di s cu ss e d in thl s paper.
c o n du ct ed u s lv,_ v ne o f the three avallahle Cabinet N o . I contain s s ignal con d ltionln o r o t o r hubs: t ee t e ring, a rticulated, o r 3 eq u i p mentc o n s i s ti ng of th e f ol lowi n g : 3 _ ),_ff ' i Mod e l 122 di ffere ntia l D C amplifi e rs ; a rem ote d es cription o f so m e r e p r e s e ntati ve st ud i e s will • shun t c ali br a t i on box th at allo w s re m ote be p resented to g t v e the re a der so m e i ns i ght ;' i ns e r ti on an d remova l of a c ali br ati o n res ist o r tn to the rese a rch do ne at t h e TDT . Al s o, so me for a n y dat a ch a nne l ; m onit o r b o xes that al l ow f ut ure p l an s will b e b r i e fl y d i scussed.
t h e output of a n y of the Neff am pl i f i ers to be . m on i t o red; a c ont ro l unit th a t suppl t es pow e r Conformabl e Rotor Studies to , a nd rec e i ves s t gnals from t he s i x co m pon e nt s t ra i n - gage balance mo unted t n the A R ES m ode l . On e a rea of res e arch tha t has been _ Three ou tpu ts (PC, AC, and c o m b in e d DC a n d _ ) c onducted t n the TDT has been conformable rotor , a r e a va il a ble from ea ch ba l ance ch a nnel. , i s s tu di e s , specifically the Ae r oe l ast t c a l l y cont r o l un t t al s o allo w s the output of ea c h C on f o r ma bl e Ro t o r (ACR) concept (ref. 1 3). The b a lance channel t o be elect ri cal ly " zeroe d ". potent i al of a confo rm able ro t o r to alte r C a b i net No . 2 conta i ns cont r ol un i ts as unfavorable blade s p a n wts e and az im uthal lo a d " fo ll o w s: a 3- c ha nn e l Fou r th H arm on i c G ene r at _r d i s t r ib ut i o n s h a s been anal yt icall y and !i ._ that can pr o duce a fourth h arm onic s ig na l f o r e xpe rim en tal ly i nv es t igated b y s e ver al research r each of t he s wa sh plate a c tuators; a re sol v e r g r ou ps ( r ef s . 1 4 - 15 ). D u ri n g t h e t es t s in t h e that uses output f r o m po t entto m eters o r st r ain TDT, the aeroelast t c me cha ni s m l t nk tng r o t o r q a ges on the m ode l h uh t o d etermi n e rotor conf ig u rati on per f o rm ance a n d l oads to bla d e # l ong it ud i na l a nd l a t era l f l apping, and b l ade de fl ec ti on wa s d ifficult to de t e rmi ne. I n an c on t n o ; a decoder t ha t m o nit o r s s w as h p l a t e ef f o rt t o )l nde r stand th e coup li ng be tw een po s iti o n i n order t o dete rmi ne r ot o r c o llect iv e conf ig urat i o n r es p onse and t h e resul t i n g ro t or i; p itch an d l ono tt ud t na l and l a t eral cyclic ae roe l ast t c en vi ron m en t , a se ri es of p a ra metri c s_ p it ch ; a T r a n s i e nt C o mm a nd Genera t or that t es ts was initiate d. Sin c e the r ot o r b l ade tip 1, p rod u ces sig n als us e d as inp u t t o t h e mod el operates i n a v er y in flu ent ia l port i on of t h e : _ ' swa sh pla t e, a n d all o w s os ci l l a ti o n o f th e m ode l r o t o r d i sk, empha s i s wa s g i v e n t o par a meter L_ : - sw a sh : la t e wlth the f o ll o wi n gwa ve f o rm s: a ch ange s in thi s are a . _- s i ne v v e, doubl et, s tick - s tlr, a nd const an t _ sp ec t r a li npu t; a nd a 7- char m e lp ie zoele ctr i c S e v en bla de tip s hap e s w e re t es t ed o n a _- a ccel e r o me ters ignal c o n d lti on l n a un it. f ou r-bl ad e d art icu l a te dhu b us ing tw o s et s o f ' i " Ca b in e t No . 3 pr o v i des t he el e ct r l c a l n o w e r f o r i ns tr umen t ed m ode l ro t o r bla des of c u rre n t the variou s in s trume n t a tion a s wel l as the p l anformde s ign. One hl ade s et wa s of ' diglta l d i s play s on t h e mode l contro l p a nel, conventiona ls tiffne ss ,whi l e the oth e r had Cabinet No. 4 cont a in s a time code ge n erator reduce d tor s io na l s tiffne ss . The s e ti p sh ape s t h at can q ene rat e o r read a n IRIG A o r B c o d e d ( F ig u r e 1 3) were w el l c on tr o l l e d wit h r eg ard to s i g nal , an d a 14 -ch ann e l Ampe x P R 22 00 ana l ', g In e rtl al ch a rac t eri s ti cs (ref. 16). T h e use of t ape reco r de r, a Fr eon t es t atm osp h o_ , , d ad bl ade a n d ti p co n structio n ,an d enab l e d a repre s ent a tiv e ARES Software aero d y na micenvironme n tto he maintained during
i
t he t es t s . T h e te s t _atrtx f o r t his . - Seve ral d ata r educ t io nc o mp u t e rpr oa ram s i n v es tigati o ni s sh ow n in T a b le V. \_ are u ti l izedboth during and after te s t i ngwith th e A R ES mo de l. T h e p rimary d a ta r e d uc ti on Si gni fi c antp e r fo rmanc ea n d loads , c odes used wi l l he briefly d i s c ussed . A real- d iff e rencesw e re p r odu c edb y th e d ifferen t tip !
mo n itor t u nnel c o ndition s a nd o utp u t fr o m th e exh ibit ed l o w os ci ll at o ryl o ad s al s o had the time pr og ram t s empl o y ed du rl n a te s tln_ t o s h a p es a n d stif f n esses . C onf l gu r a tlo,ls which !"
m o del' s s tr a in-gagebalance. T h e paramet e r s be s t perform an ce,while t h e c on fi g ura t io ns with th a t c an b e d i s pl a y ed whil e the t un n e l an d p o or pe rf o rm a nceg ene rated the hi gh e s t l o ad s mo de l ar e ope ratln q ar e sho w n i n T abl e IV. (Fi g ure 14). Another intere s tingresult of _ T he s e v a lu e s a id in s lm ul atln q a g i ve n r o t o r the se te s t s wa s t h e s tr on g co rr e lation b etwee n ta sk d u rl nq pe rf o rmancet es tl na . Fo r az im u tha l va r i a tionof e la s tic twi s t an d r o t o r a er omec h a n lca ls t ah illtyt es ti n g th e b eha v i o r. As n o t ed i n r e ference 16 , t he movinq-b l ock m e t h o d d esc ri be dIn ref e rence 1 2 c on flg u r_tlonsw h i c h ex hibit ed s mal l a z im u thal i s used o n-li n e t o de te rmineth e s y s t e m a c ti v ityi n e la s tic twi s t w e re the b es t damplna. The movl na - b lockc o mp u terpr o Qram i s p e rf o rmers.
used Interactlve l y, and an example of it s output i s s hown in F igure 10. For proce ss ing The u tili z ationof a conf o rmablerotor d a t a aft e r t es ting i s co mplete,tw o data c oncep t s h ou l d b e eva l u ate dno t onl y f o r h ow re du ctle' p rogram s are r ou tlne l yused. One of s ucce s sful l yit ac h ieves it s perf o r ma n ceand t h e s e pr o qrams i s u s ed to reduce data from the l oad s g o al s , but a ls o ho w w ell it can be str a ln-g a ge h a lance and p re s ent it In ha t h "fle l de d ". T h at i s , h ow muc h cha n a e (if any) e n gi n e e ri n g un it s and coe fficientform. i n cu rr en t i ns tallati o n, mai n t en anc e , a n d r o t o r Exam p lesof o u tp u t from thl s program are s h o w n tuning i s nece ss ary for the new ro t or concept In F ig u re 11. Another po s t-te s tproqram is to he emp l oyed. O ne aspect of this "fie ld ing" ava ilablet o p erf o rm a h a rmo n ic an a ly s i s of pr o c ess is r o t o r tra ck in_ se n s i t ivityan d its l s el e c tedd a t a c ha n n e ls . E x am p le s o f ou tput Im pl lcatio ns to rot o r a nd fu s e l a a eload s .
" f r .m thi s pr o gram a r e sho wn I n F i gu r e 1 2 .
A s p a rt o f the co n f o rmable r o tor s t ud ie s _" Re searchStudies in the TDT in t h e TDT, a rotor track s en s itivity : _ i n v es ti g ati on wa s c ondu ct ed in w h ic h b la des of In recent yea r s b o th t he TDT a nd the ARES conve n tlonalan d re d u c e d tor s ional s tiffne ss h a s in vo lv edro t o r p e r fo rm ance, bl a de lo a ds , t o a t es t matrix (Tab le Vl ) d es i g ned t o p e rt u rh % a e r o mecha n l ca l s t a b ilit y ,a nd ef f o r ts t o r edu c e the track o f o n e blad e. T hl s p e r tu r b ationw as % " h el lc op t e rv ib r ation le v el s . A h rl e f 4 ac comp li shedb y use o f t_ a lll n g- e dget a b i h ave b e en u tili z e d for rotary - wlnatesting th a t wi th r e presentative s w e nt tl ps w e re su h_ e ct ed The succ e ss o f the HHCin reducing de f le c tion. Initially , th e tab s w er e fixed- s y s tem vibratory res D on s e s i s sh o w n in unde flectedan d th e r o t o r wa s tracke d i n Fig u re 16. Variatio ns o f the ARES s train-ga g e hover. One-per-raylo n git u dinala n d lateral balance and fu s ela a eaccelerometeroutput s wit h fixe d - s y s tem l oad s were mi n imize d ,and forwar d and w i thout the HHC operatinaindicate f l ight te s ting was b eg u n. Forward flight su b s tantia l cqntrol of t h e flxe d - s y s tem t e s tingwas then repeate d with the vibrat i onlevel s . It sh oul d h e noted that traillng-e d getab s d eflecte d on one bla d e. In althoug h the re a uiredc o ntrol Innut s are small bot h ca s e s d ata wa s ac qu ireduntil either the (le ss than one de q ree) t h e blade and control t es t matrix wa s co mp l ete d or un til rotor l o a ds s y s tem loa ds u s ,Jolly increa s ewith t h e HHC b ecame prohibitive, s y s tem operatin1. An exa_le of this i s s hown in F iaure 17.
The ela s tic re s ponseof the b a s elineand t o r s ionallysoft blade s to tab def l ectionwa s The s e win d -tunne l te s ts were the fir s t correlatedwith flxe d - s y s temloads (ref. 17). opportunityto evaluate an adaptive control T hi s wa s done t o a ss e ss th e eff e ct o f p o tential s y s tem us in a op tima l c o ntrol t h e o ry for m o del trackingproce du re s o n bl ad e re s pon s eand t h e helicoptervibratio n red u ction. T h ese accompanying"f us elage"vibrationenvironme n t, experlme n ta ls tudie s hel p ed acce l eratet h e The t o r s l o nal l y s oft b lad es were fo u n d t o s ucce ss f u lapplicatio n of the HHC concept to a respo n d very d lfferent l ythan the ba s eline f u ll-scalehelic o pter (ref. 20).
blade s to t h e s ame tab d eflection. A s s h ow n in Fig u re 15, the tor s ionalmoment s for both s tiff Aermoec hanlcalStability Investigations a n d s oft bla d e s , d u e to tab d eflectio n , re s u l ted in differentbla d e flapping Experimentalan d ana l ytical studies have magnit u de s ,f la pwi s eload s , and fixed- s y s tem al s o been recentlycon d uctedto inve s ti q atP_; , e vibration, ground re s onanceof s oft In-planehl n geles_ T her e f o re, t he e v aluation o f p erf o rmance r o t o rs ( ref. 21). The se e ff o rts wer e Intende d _ an d l o ad s f o r a n a dv anc ed r o t or d e s ign w as t o ai d in the identification o f an analy s i s ac co mpli s h ed u s i na ARES in a re p re s entative t h at can be u sed in b o t h t h e d e s ign and te st ina aeroela s tlc s imulation. In addit i on,ca us e s pha s e s of hin a ele ss an d bearl n gle ss rotor for the rotor behaviorwere fo u nd while d evelopment. Another o bjectiveof the re s earch identifyingfurther area s of practi c a l concer n wa s to developan experimenta l techni a uefor for thi s pa s sive rotor concept, b la d e excitationand d amping mea s urement s in t h e rotating s _ s tem.
Active Control Te stinQ The rotor mo d el u s ed for thi s T e s tin a of active c ontrol c oncept s to inve s tigationis a soft in-planehin a ele ss s re d uce flxed- s y s temvibrationlevel s h as al s o rotor that i s not a dynamicallyscaled b een c ond u cted in the TD T u s in g the ARES. representation o f a s pecifi c a ir c rafthub, bu t Specifically,this testing involved the Higher rather i s representativeof a typical Harm en ic C o ntrol (H HC) co n cept ( ref. 18 ) . T h e f u11 - sc a l e de s ign b a sed o n Mac h nu m b er, _ s s !
appr o ach com b inedHHC experimental s tu d ie s with ratio, and fre ou encysimu l ation. T h e mo d e l the deve l opmentof control alQorithms s uitable blades were fa b ricatedwith fiber al a ss s par s for real-timeimplementationo f the require d s pecificallyfor testin a in Fre o n. T h e rotor control input s , huh (Fi q ure1 8 ) con s i s ts of meta l f l exure s to acco r , Bodate flap an d lead-la q moti o n s an d a The HHC concept involve ss uperim_oslna mec h anical feathering h lnQe to al l ow b la d e fixe d - s y s tem s wa s hplatemotion s at the b lade pitch moti o n. The fla p and lead-lag flexure s pa s sag e freo u en c yon th e ba s ic c ollectiveand are e ac h s traln-gage d an d cali b rate d t o measure cyclic re q uirement s . T h e phase and amplitude motio n in tho s e directions. The hlngele s sh uh _ of the HHC inp u t s are ch os en to minimizethe ha s the capability t o p arametricallyvary b l ade b l ade pas s age re s pon s e s transmitte d to the fixed sy s tem. Severa l contro l lerswere s weep, droop, and precone of the bla d e d eve l o p e df o r t h e HHC s y s t e m. For application feathering axi s .
to ARES model testino in the TDT, the The ComprehensiveAnalytica l Model of controllerswere pro a rammed on the TDT data Rotorcraft Aerodynamicsan d Dynamic s (CAMRAD) ac q ui s iti o n s y s tem. Det a i ls o f t h e c ho ic e o f co mp u ter p r o gram wa s us e d a s t h e t h e o retical elec t roniccontrol d e s ian s and s oftwarecan be too l for t h i s inve s ti a atl o n(ref s . 22-23). T h e f oun d in reference s IB an d 19. s tructura ld ynamic mode l of the r o tor Inc l u des ela s tic d egrees of freedom in flap ben d in g , E x p e rimentalverificationof th e HHC lead- l ag b e n di n o , t o r s ion a nd a rigid pit ch co nc ept invo lved seve ral te s t s wfiere vibratory - degree of freedom. T h e bla d e i s repre s ente d by loads to b e s uppre s se_were o b tainedeither a sp anwl s e d i s tributionof ma ss , flapwl s ean d from t h e ARES s t raln-gageba l ance, or mode l c h or d wl s eben d ing an d tor s ion s tiffne ss an d • f us e l a g e acc e l e rometer s , an d t h e s e s l a nal s were momen t o f inertia. An e s timated s tructural u s ed a s input s to the HHC s y s tem. During t h e s e d amping h a s _I s o b een inclu d ed in t h e rot o r s tudie s ,a fo u r-bladedarticulatedmode l rotor data. The "aircraft"mode l con s i s t s of e l a s t'c wa s t ested over a range of advance ratios m o tion of t h e ARES s train-gagebalance and s im u lating Ig fllaht wlth t h e rotor trimmed to the s haft. Data were recorde d to quantify the s upport sy s tem in the wind tunnel. The CAMRAD inp u t d ata inc l ude s qen e r a ll z e d m ass , . _ v ibratoryl oa d lev els witho u t t he HHC s tr u ctural d am p i n g, fr e o ue ncyan d mod e sh ap e o f operating. The HHC s ystem was then activate d the "aircraft"ela s ticmo d e s . The s e and a l lowed to converge. F ixed- s y s tem characteri s tic s are s et to the mea s ured vi b rationlevel s an d blade loa ds were then recor d e d . 5 value s . T h e rotor hla d e aerodynamicforce s are _N Pl I • "" " " ............... - ' '_ - '- -_-r_ : '_r_., - _ ., . L , •_ calc u la t edus i ng 1 1 f tl ng l in e t h e ory a n d s te ady In g ener a l,th e p u rp o se o f t he te s t was to tw o -dlmen sl onal airf o ilcharacteri s tics wlth pr o vi de ah experi me ntal da t a h ase to h_ us e d corr e ction s for un s teadyand three - dimen s lonal for correlationwith analy s e s in the design flow effects. The degree s of free d om u s e d In developmentpha s e of th e Jg ) pr o oram, qp_riFir the stahllltyanaly s i s are the flap an d la g te s t _Jectlves were to d eterminewinq / rotor motion of the bla d e s , th e b o d y pitch an d roll s tabilityin the airplanemode, and tn measur e _' " m otion s and rotor d ynamic inflow, rotor and control s yste m loads and vihratlon data primarilyin the hellccpter-to-alrplane The test t e chniq u econ s i s tedof two conversion corridor. An initial test series s teps. First, the mo d el wa s excited in the was conductedto deter m inedesl o n parameter fixed system by applying a longitudinalcyclic effects on an early haselln e design• A second o s cillationto the rotor through th e test series was conductedto determinethe : . swa s h p late. The amplit u de o f the s wa s hplate eff e cts of de s ig n updates.
os cill a tionwa s n o minally0.75 d egrees. The _i freq u ency o f the swa s hplateo s cillationwas The m o del wa s te s te d in both air (l o wMach Inltiallys e t eq ua l to the fixed-systemvalue number o peration) a n d Freon (hlah Mach number of the rotor In-planefrequency (lead-laq operation)at d en s itie s correspondingto regre ssi ngmode) pre d ictedhy CAMRAD. The altltudesfr o m sea level to 15,000 feet. A swashplateoscillationwas then adjusted variety of model parameter s were tested. These sl i gh t l yt o ob t ain the maxim u m r o tor In-plane i n c luded : i) pyl o n t o wlnq l ock ln o (on an d off !
r espo ns e. Onc e th e rot o r In- pl aneresp onse wa s do wn s t op ),2) r o tor r p m, 3) wlng a e r od y n a m i c s , e s tabli sh e d ,the s wa s hplateo s cillati o nwa s 4) wing s par s t i ff n e s s,5) rotor p itch-flap removeG an d the m o ving-block p roce du rewa s c o upling, 6 ) rotor co n trol _y s tem s tiffne ss , 7 ) : i n iti a te d to de t e rmi n ethe s y s t e m d a_I ng , a c on i ng hln ae h ub , and 6) r o tor bla de s tiff n e ss . Suh-crltical d am_ing data Were T es ti n g wa s c ondu ct ed I n bo th hove r a nd ob tai nedb y exc itin g th e m ode l I n th e wl n o _:_ f o rwar d fli a ht. A s am p le o f t h e p re d icteda nd b eam , c ho r d , a nd tor s i on mo des us lnq a u ninue me asu r ed h o ver r esul t s i s sh ow n in Fig u r e 1 9 Fre on j e t s y s tem m ou nt ed on t h e wl no . T he F for a collectiv e pitch o f e i qh t d e g r ees . T he s y s tem d am p i ng wa s th e n e xtracte d from th e pre d icted an d e x perimentallea d -laa freque n cy mo d el re s pon s eto thi s excitation us ing t h e are s e en t o be In g o od a g reem en t. The m o vi n g - blockmeth od a nd fr om decay trac e s o n a regre s singlap m od e d amping in th e fixed s y s tem s trip chart rec o rder.
Is al s o well predicted. An u nstahle r e gion is . in d icate dne ar the reqre ss l nq lag-r o ll F o r almost all c on figuration s t es t ed , the coa le sen ce r o tor s p e e d . D u e t o ro to r s tre ss wlng b e am mod e ha d t he l o w es t fl u tter s p ee d s .
lev e l limitations,t h e test could not he The s i ng le ex c ep tionocc u rr ed du ri n g t he first carried out for rotor speeds hl q her than 650 series of tests when a chord _oe instability rpm. Presented in Flqures 20 and 21 are wa s in d uceduslno a s par desl a ned for that sole a,_lytlcal an d ex p erimentallea d -l a g da m p inq ob jective. In a d ditlon,th e r e wer_ s e v eral ( re su lt s w h ich s how the eff e ct of bla de d r oop in s ta nces I n the s ec ond se ri es o f te s t s where _n d pre-coneangle s on t h e da mpin g level s in the c h ord mo d e a p p roac h e d an instabilityat the forwar d flig h t, same conditionthat the beam mo d e hecame critical. Figure 2 3 show s that the various T hes e wl nd -tunnelte s t s aid ed in d es ign u p d ate s i n crea s e d flutt e r s pe eds . T h e | de v el o pin g a s ati s fact o ryt ec hniq u efor data s h o wn in the fig u re are f o r t he mo d el i,_ | aeromechan l c dl stabilityte s tino,a s well a s air wlth t h e pylon locked to t h e wing (on
!
I den tlf y ln a an analy s i s th a t p r oduced h ood down s t op )a nd u nl ock ed ( of f do wnst o p). V ari o us .
co rr el a tio n with th e expe rime n talr esul t s , p erce n tagesof n o mi n al r o tor speed (87 4 RPM ) were s e lec t e d f o r te s tln_. T h e act u al spe e d at _ - Tilt-RotorR esearch which the Cn s tabllitles o cc u rred h a ve b een : normalized to a referenceflutter spee d .
The most recent rotary-win g te s t s Initial predictionsof flutter speed proved conductedin the TDT di d not involve the ARES. unreliable. Con s equent l y,an immediateoutcome The s e tests were conductedin support of the of the first ser i es of test s was a critical design developmentphase of the Joint Advance d re-examinatlonof analysesand the model used VerticalLift (JVX) tilt-rotoraircraft. Test s therein. A s a re s ult, the de s ion up d ates were In the TD T o f a e r o e la s tlcmo dels o f tilt - r o t o r s uc ces sf ul no t only in ral s l n Q flutter s p ee d s , _ con cept s suc h as t h e J V X I s no t a re c ent b u t w e re a l s o v a lu ah l e i n ve rifyingthe d evelopment . Durinq t h e late I g fO' s an d early improve d analyticalmet h od s .
Ig7 0' s , s e v er a ltllt-r o t o r c o ncept s w e re t es t ed in the TD T ( r e f s. 24 -2 6). T hes e t es t s As in p r ev l cus s tabilit y t es t s , the " c on tri bu t eds i g nificantlyt o the suc ce ss f u l ca pabilities o f the TDT were u ti l ize d t o d evel op ment o f the XV-1 5 tilt-r o t o r aircr a ft, provi d e _ hlgh quality da ta ba s e for ve rific a tiona nd im p rovement o f a nal y s e s dur i ng : 4 The mo de l us e d in the TDT t es t s w as the d e s i gn deve l o p m ent pha se of an adv a n ce d desig n e dand bu i l t b y B el l He l lcopter-Textron r o t o rcraft con cept.
0 . 2 - s i ze a e r o e las tt c ally s cal ed , se mi- s p a n Rese arc h Opportunities _i a nd t h e B o eln g - Ve rt o lC o m p any a nd w as a m od e l o f a pr e liminary j V X des ign (F ig u r e 22) .
m T he mo d el con si s t edo f a c antile v er ed wln a a n d Fu t u re plan s f o r the T D T a n d ARES inv o l v e ._ pyl o n / rot o r s y s tem that c ou l d be o peratedwit h g us t s en s itivity s t ud ie s o f a d vance d rot o r the r o t o r e i t h er po w e r ed o r wtndmtlllnq, s y s te ms su c h a s h in g ele ss a nd h e a rin g l ess
I
c o n ce pt s . Re f e re n ce 27 in d i c ate s t ha t a d v a nc ed I 6 r o t o r s y s tem s may be sus ceptl bl- t o _,_
L
d i ) g us t - ln duced limitation sdu e to rotor loads a n d 3. Ta ylor , R o b e rt B.: He li c opter V ibration respons e c haracteri s tic s . F o r e xa _ l e, blad e Redu cti onB y M od a l Shaping. P r e s entedat lo ading s may become exce ss ivelyhigh w h en g us t s t h e 38th Ann u a l F o r u m of the Americ a n are e n c o untere dd urin q n a p-of-the - earth H el ic opterSo c iety, A h aheim,CA, May L _2.
• ' . man e u v e r s . I n crea s edl o ad transfer through a d van c edhub de s ign s _y al s o re s ult fr o m rotor 4. Miura, h.: Overview: Applicationsof " gu s t penetrations. NumericalOptimizationMethods to H eli copt e rDe s ign P r ob lem s . Pre s en t ed at _ . T h e pl a n ned re se ar c h appr o ac h for r o tor the Sy_o s ium on Recent Experiencesin gus t r espon se s t ud i es i n the T D T i s a s f o llow s: M ult J d i sc l pl i n a_ A n a l y s i s and _w _a s ure the fl o w characteri s tic s of the TDT Optimization,NASA Langley Research gust system at s pecificmodel rotor locations Center, April 1984.
_ ' i n t h e bm n e l te s t se ction f o r o p e rating con d ition s where i_ortant aeroelastic 5 . H u nt, G. K.: SimilarityRequirementsfor to he followedby a series of model rotor tests R.A.E., Farnboroug h ,C.P. No. 1245, Ja_..
where parametricvariationsof hub geometry and 1 9 72.
stiffnes s ,rotor operatinaenvironment,ard __ phe no m en aar e pre d ictedby a naly ses . Th i s i s Aer oe la s ticM o d e l s o f H e lic o pterR o t o rs.
gust signaturesare ma d e and the rotor and 6. Lee, Charles: Weight Con s iderationsin fix e d -s y s tem lo a ds are o b s er v ed a nd c o r r elat ed Dy n amicallySimilar Mo d el R o t o r Oesinn.
with analy s e s . Pre s ente d at 27th Ann u al Conference of t h _ Society o f Aero. W e i g ht En g i n e e r s , Inc., e M od ifi c atio ns are al so p la nned f o r th e New O rl_a ns , LA, 1968.
-. A RES m od el. Th e se mo d ificati o n s consist of . IK s tructurala n d i ns tr u mentation improvementsto 7 . Yeager, William T ., Jr., a nd Mantay, Wayne the model s ystem. The maj o r mo d ificatio n R.: Correlationof F ull-Scale Helicopter planned i s to a d d h ody dearee s -of-freedom in Rotor Performancein Air with Mo d el-Scale
I
pitch, roll, yaw, an d longit u dinaland lateral Freon Data. NASA TN D-B323, Nov., 1 9 7 6 .
translation. The s e motion s will be six hydraulicserve-actuator s . The Fluid for Aero d ynamicTe s ting. NACA serve-act u ator s will b e electronicall y TN-3000, 19b J .
controlled to continuou s lypo s ition the model i_ ac co mplishedby mo un t i ng t he en tire m o del on 8 . Hub er, P a u l W. : Us e o f Freon-12 a s a t o s imulateaircraftwith variou s inertial 9. Hey s on, Harry H.: Theoretical Stu_ of characteri s tic s . It i s planned to use t h i s Con d ition s Limitln q V / STOL Te s ting In Wind sy s tem mainly for aeromechanical s tability T un nel s wit h Soli d Floor. NASA TN D-5819, in v e s tigation s . J u ne 1 9 70. _ ConcludinaRemark s 10. Reed, Wilmer H., Ill: Aeroela s t l clty Matters: Some Reflection s on Two Deca d e s Thi s paper ha s s hown the importanceof of Te s ting in the NASA Lan a ley Tran s onic proper dynamic s caling in identlfyinQand Dynamic s Tunnel. NASA TM-83210, " solving rotorcraftaeroela s tlcproblem s . The September 1981.
i unique q ualitie s of the Langley Transonic | Dy n amics Tu n n el ( T DT ) and its a ss o c iated 11. Cole, Patrlc i aH.: Wind-Tunnel Real-Time facilitiesfor model rotor aeroela stl ctestin g Data AcquisitionSystem. NASA TM 80081 t have been described. Aeroelastictesting of April 19 7 9.
model rotor systems has b een shown to he a ne c ess arystep in the design of ad v a n ced 12. Hamm o n d , C h arle s E., a nd Dog q ett, Ro h ert rotorcraft. T he utili z ationof the s e V . , Jr.: Determinationof Suhcr i tical fac i litiesfor rotor testln a which ha s general Dampln q by Movln q -Block / Ran d o r _dec applicabilityis emphasized. A d ditionally, Applications. NASA SP-415, Oct. 1975.
several r e searche x periencesha v e been c i ted to define the scope of model rotor testin g in t h e 13. Blackwell, R. H.; and Merkley, D.J.: T h e TDT as well a s the detail s of the methodolo a y Aeroelast l callyConforma h leRot,or " u se d to o btain so me un iq ue r esul t s . Concept. P reprlnt No. 78- 5 9, A _rl c an He l icopter Society,May 1978.
Ref erences p 14 . D e mon, Gll dd en s S.; T ar z a n ln, F rab_k J.; . I . Hammo nd ,C. E., and W e ller, W.H.: a nd S h aw, Jo hn , Jr.: Investigationof - _ _ Wind- Tu n n el Tes ti n g o f A er o e l a s tlca ll y Aer o ela s tically Adap ti v e R o t o r Sy s t e m s .
_ , S c aled He li c o pter Ro t o r M od el s. Army P ro c ee di ng s of a Symp os i u m on Rot o r S c ie nce C on f e rence,W es t Po i n t, NY, 1976. Tec h n o l o gy,A_rlcan He l icopter Society, Augu s t 1976.
" 2, Moff l tt, R o be rt C . , an d Bi ss e ll ,J ohn R. : T h eory and Applicationof Optimum Alrloa ds 15. Sutton, La_renceR.; White, Richard F '., to Rotors In Hover and Forward Flight. Jr.; and Marker, Robert L.: Wind-Tunnel 39 th Annu al F o r u m P r oc ee di ng s , A mer ic a n Eva l ua ti o n o f an Aer o e las t l cal l y
i
H el l co oter So ci e ty, May lq R 2. C o nf o rm a b l e R o t o r. USAAVRA D COM T R-BI - D-4", 198 2.
i
I , 1 6. Mantay , Wayne R .; a nd Y ea ger, William T .
Jr.: Parametric T ip Effect s f o r C o nf o r mab l e Ro t or A p p licati ons. N A SAT M 22 . J ohnson, W .: A C om preh ens l v e An alyti ca l 8 5 68 2 , Augus t 1983. Mode l o f Rotnr cra f t A e rodyna ml c _ and D y n a m ics, P a rt ! - A n a l y s t s Developm e nt + 17. Mant a y, W ayne R.; a n d Y e age r , Wi ll i a m T., NASAT M -8118 2 , 1 98 0 .
Jr .: Aer o ela s ttc C o n side r a t i ons f o r To r s i o n a l l y S o ft R o t o r s . To b e prese n t e d 23. J ohnso n , W . : A C o m p r ehe n s i v e A na l y tical at t he A me rica n H elic o pt e r Soc iety M od el of Rot o rcraft A e r ody n a mic s an d S pe cia lis t s' M ee t tn o on Ro t o rc r a ft Dynamics, Par t II o Us e r's Ma n ual. NASA D y na mic s, NASAA a n e s R e sea r ch C en t er, TM - 81183, 1980 .
N o ve m be r 19 8 4 .
24. Kva t e rnt k, R. G.: Ex perim en t a l and 1 8 . Ha mm o nd ,C. E . : Wi nd - Tun n e l Resu lt s A na l y t i ca l Stud i es i n T i lt - Roto r S h owi nq Ro t o r Vthra to r y Loads R e du cti on Aer o e last i c tt y . N ASA5 P - 352, Feb . 1 974.
Us i n g H to he r H a r_ n t c Rl a de P it ch .
Jou r nal o f t he A_rt c an Hel i c op t e r 25. K v a t e r n t k, R. G . : S tud i es i n T i lt - Roto r Soci e t y , J a nua ry 19 83 . VTOL Air c raft A e r oel a s tl ci t y . Ph.D .
Di ss erta t i on ,Ca s e W est er n _e s er v e 1 9 . M o lu s l s , J. A.; Hamm o n d , C. E.; and Clin e , U n iv e r si t y ,Cle v ela nd , O H , Ju ne Iq 7 3.
J ohn H.: A Unifie d A pp r oa ch t o t he Optimal De s ign o f A d a p tive a n d G a in 26 . Gaffe y , T.M.; Ye n , J . G.; an d K v at e rn i k, Sc h e d u l e d Contr o l le r s to Ac h ieve Mi n im u m R.G.: A n aly s i s a nd M od el Te s t s o f the Ro to r V i b r atio n . Jo u rnal o f the Ameri c a n Pr o pr o t o rDy n amic s o f c Ti l t- P r o p roto r Helic op ter S o ciety,Apri l 1 9 83. VTO L A i rcraft. Alr Fo rce V / S T OL Tec hn olog y and P l a nni ng C o nf e re nc e . La s 20 . W ood , E . R .; Po wer s , R. W .; Cl i n e , J .H. ; V eqas , N V, S e p t. 1969 .
t
Hamm ond,C . E . : On D e v e l op t n q and F li gh t Tes ti ng a H ig he r Ha rm o ni c Cont r o l _ vs t e m . 27 . S at t o, S ; Azu m a, A . ; a nd Na a ao, M . : G ust Pr esen t ed a t t he 39 t h A nnu al Fo r u m o f th e Re spons e o f R o t a ry W ln g A l- c raft and Its American Hell con t e rS oc ie t y, St. Lou i s , Alle v i a tion. Ve rtl ca , V olu me 5, N u m h e r 2, ; Mi ssou ri, M ay 19 83 . 1 9 8 1. : 2 1 . Ye age r, Wi l liam T . , Jr . ; Ha m oud a,M-N ab l l H.; a nd Mantay, Wayne R.: Aer o mec h anical Stability o f a Hino elessRo t o r i n H o v e r a nd F o rward F ll qh t: Analy s i s and Wind
|
Tunne l Te s t s . NASA TM 8 5683, Auqu s t 1 9 8 3 . _ , !
i, T ABLE I .- Pr o perti e s o f F r eo n -12a n d Air Stan da rdDay, F u l l Atm o sp h e r ic P re ss ure ?
Freon-1 2 Air Spee d of S o und, ft / se c 5 00.4 111 7 .
- I De nsi ty, sl ugs / it J .00 q9 16 . 0 023 7 8 Rati o o f Sp e cific He at s 1. 13 1 . 4 i A bso l u t e Vi s c os i t y, lb sec / ft _ 2.622 x 1 0-7 3 .7 19 x 10 - 7 ¢ _
i
t r i P '
TABLE l_. . - Sc a l ing Pa ra m e t ers f or a 1 / 5-Sc a le Mod e l i n Air an d Freon- 12 T e st M e di u m s Scal e Factor a / M od e l Valu e _ F ul 1 " Scal 'e Value _' _ . A ir Fr e on-12 - M ach nu m be r Fluid inertia force 1.0 1.0 ' Lock nu m b e r Fluid inertia fo r ce 1 .0 1.0 i F1u l( l ela s ti c fo t - ce Ro tor inertia force - _ A dvance r a t io 1.0 1. 0 F r oude nu mb er Rotor inertia fo r c e 5.0 1 .0 i t : R oto r w ei g ht fo T _ ; Re y nold s nu n , h e r Fluid tnertta f o rce 0 .2 0 . 53 I _ [ _ 'T t l l d vi scous forc e i • - TI_ 0.2 0 , _ 6 ) . : A ngula r vel o c i t y 5.0 2. 24 [ - . - k.
" _" - . _ Li ne a r v e l oc ity 1 .0 0 . 448 } ,-::, _ Fo r c e 0 . 04 0 . 0 33 4 i ": _ M o ment 0.008 0 .0066 7 : P ow e r 0. 0 4 0. 0 14 9 t Struct u ral fr equ en c ie s (per re v ) 1 . 0 1.0 !
M ass 0.00 8 0.0 334 '_!
Stiffn ess 0 .001 6 0 . 00 1 3 5 a Based on s t anda r d da y c o nd itio n , f u l l a t m os p he ric p r essu r e I ' I ( TAB L E Ill. - TDT Tunn e l W all C o rr ec ti onsTo Rot o r T ip Path P la ne (C L - .0 07 6, aT PP = - 8° ) ' R oto r a o r rpp, deg.
Rad i us f t. p = . 1 5 :p - . 2 0 p " . 25 p - . 30 - 3 .45 .25 .1 7 .12 4 . 80 .46 .30 .2 1 ' S > 1 . 7 1 .47 .32 I D 6 > I > I . 6 7 .47 z _ N ote: u " Ad vanc e Ra t i o , I ; T A B LE I V . - P a r a mete r s for D i s pl a y Duri nq Model a nd T u nn e l Op era ti ons Definition Un its , Shaft Angle of Attack (leg.
'_ Co / o Rot o r D r ag Coefficl e nt / S o li d l t y Ra tio --- o: :i CH / o Ro t or Drag C omponen t P er pendicular t o i Ro t o r Shaft / S o li d lty R ati o -- - I CL / a Ro t o r Lift C o efflclent / e l l d lty Ra ti o --- CQ / o Ro t o r To r que C o efflclent / Soll d ity Ra ti o - - - CT / o Ro tor L ift C o m po n e ntParall e lt o • Rot o r Shaft / S o lldlty Ra ti o --- - ; " C y / o Ro t o r SI d e F o rce C o effl clent / Sol Idlty R atl o : Per p end icu la rto R ot or Shaft -- - D R otor Drao F orc e Ib s .
H Rotor Drag Force C o m po n e ntP e rpen d ic u lar to Rotor Shaft Ibs .
: HP Rotor Ho r sepower R e qu t red --- , L R o t o r L ift lb s. i i i H T R ot o r Ro t a ti o nal T ip M a ch Numbe r - -- ] M 1, g o R otor A dv a nc lnq T t p M a ch Nu mb e r --- H. Tun n e l F r ees tr e em Ma ch Nu mb e r --- ; Q Ro t or T or o u e tn- lbs.
"4 q Tunn e l F r ees tr e amDynamic P r ess ur e I bs / ft z "i : T Rot o r Lift Fo r ce Comn onen t P arallel _k i to R o t o r Sh aft lbs.
i i T® Tunnel St a tic Te m pe rat u r e ° F l Y Rot o r Sid e Fo rc e lb S . m u Ro t o r A dvance Ra ti o -- - e' I0 t e T a bl e V Ta rg et Te s t Co nditi ons C L as -- c_ s I CL C L .30 .65 -6.0 ° ,-7.8 ° .0 6 -4.5 ° ,-5.9 ° .08 -3.6 ° ,- _, .7 ° .10 .68 • .70 + + +
- _+ - '_ . , 7 - + - _ - '° . + - . o ° . ,. , _ _7. , . .o+ :+ . + . _ . , . _ , . ,_
L_ .4 0 . 6 3 - 1 0. 6 °,- _ 3. 6 ° .0 _ -8.0° 1 -1 0 .3 ° .08 - 6 .40 , -8.30 .10 Symb ols d efi n e d in TABLE IV !
i
t
T a bl e V l . T ra c k S en s iti v ity T e s t C o ndition s u as CL Tab D e f le cti on M T . 05 0 ° . 075 0°, 4 ° do w n . 6 5 30 -5 ° _
_oo° + . + +
. 40 -I0° !
Sy m bol s de fi ned i n Table IV
)
I Q
____j
I _ = 0 .30, M (IO 0 0) = " 0 .8 5 , a S= O °
* Fr e o n _ - -T - I I [ ] / i _ , ._Y
. 3 / _ _ . l o P_"_^ R_ ,o n B I I _ I I N or m ali z e d _ Reynolds no . : l. e x IC°. a : O.11 0 0
*° I , •,r -- "
st r e ngt h C L / a .0 6 _T-__ old s n o " : 4 ., 3x 1 06 , a: O. 110 0 re q uired _- [- -_- -- -JF _ R , _ "M ds no, = !O x 1 0 6 : : O. 1100
JJ; i I I n ° °:° - ° ' =
0 d _ ) 80 .0 2 F T I I ] I _ , . ,.. _ F '_II - s c a l e , ai r, , ,6 _ i i i i .. ,, ,o,_.o" :l o xes , o : o . o 4_ , Model power , hp •o= .DO 4 oo6.Do 8 .O l D.o 1 2.o 14 .o 16 . o 18 : cQ / o F igure 1.-Typica l Ro t o r M od el Po wer a n d : Re qu ir ed S_ r en gth f o r_ i ran d Freon-12. Figure 4.-Effect ofScalin g Pa r ameters on F r eon M o del and F ul l -Sca l e Rotor Perf o rmance.
U ' +t_ . " ' _ FIXED p=0.3 0 , M (I.0 , 9 0 ) = 0 . 85 X " v _ e s- , .... _c - - - sc al e cr F u ll-scale ( air L aS = 5° _ _ :_~ 0 Mo u el ( freon), oS -5° .0 6 X,_ _ - ; " . 0 2 r..M o d e l (f r e on), nS = - 1 5 ° - - - _Cy, x , M,e l ,f re on, , n S = . i0 o 0 _ _' w a _ o I " :. .04 _.._. _ _, / < Ful l 's cal e ( air ) ' °S = -1 " _ ..:I_ 14 Nt_ Ig6 .,0 IY ,OItOI U, _ : l "_ _ Ful l -s c ale , a , r) , O S : _1 50 0 . o = 0 -- $ C kL E, f f -.01 6 - . 0 12 - . 0 0 8 .0 0 4 0 .0 0 4.0 08 Co / ° Figure 5.-Langley Transonic Dynamics Tunnel.
Figure 2.- Full Scale and Model Rotor Performance.
., . : , . . . . , : . :: { ?
C t / o : 0. 05, " : 0 ._ Adva n c i n g dp __ • " _ 'F_, , , ' ' _ r _ " " . " • -_. : ._-_ o o6 Reyno l ds 3 ,", , , , ' . ' _ , '_ : " " " 0 Mod e l [f r e o nL C D / _ : - . 0 01 n u m b er __ . 00 4 - _ o Mclel ( freon), C o / o = -,003 Co / o . 0 0 2 . 006 ...........
[ Y Fu ll -s ca l e _ air ) , Co / o = - . 00 3 0 . 00 4 .... - * --- - + - ---- _ ----- _
I " l
-i .0_ - - _ -- --- ¢ : ) , = ' _) , - - 4 .- _ l l I 0 .7 . 8 . 9 1 .0 . 15 . 80 . 8 _ Q O . _ 5 1 . ( _ Ad v ancin g ti p Ma , : h n umber ] Fig u re 6.- T y p i c al Mod e l R eyn o l ds Nu m b er Fi g ure 3 .- F u ll Scale and M o de l R o tor Performance. in Alr and Fre o n. 12.
i V e rs us Ad v a nc;n g T i p Mach Nu mber . x - '% .i 1 2 _.
i ORIGINAL PAGE IS !
OF POOR QUALITY ' !
,__ " . : ' L ) .
o Figure 7.- Sketch o f Gust Vanes and Model, , With Cut_way Showing Sche m tic ,, o f Mechanism. " : Cigure 9.- A.R.E.S. Instrumentation.
).
. . 00 8 - 2F i .006 - 3 F F T 004 L og , • _l I • J J j_ 0 20 40 60 F r e q 0 I 2 3 4 Ti m e I ,_ Ampof F F Tve r s us fr e q P e a k plo t !
¢ , . i ' - .1 50 • ' A mpl . . I 00 i a i _ . •
. . i, t
0 2 4 6 T ime Figure8.- Ae " _e l asticRotor E x perimental Sign al tra ce System Model in TD T . _ ." _ Fi_,,re 10. - Sa m ple Real- T imeDisplay of Moving-Block Results.
r l : L_ ' _ - L_ C T ' r r _ ' _ TP : * E X PE_I_ ' { ' i_ T A L FY S T Et d A L AN C _ P'_ U _ , P?, P _ X 6A : HA T S TAT F ACH _ vEL _ P 9 kN = _ _ I , _ I C p_ , _ 9 x ' _ 1 3 7 6_ 7 * 0 9 5 _'_ * I *I 00w 7 _ I 8_9_ 8 5 _ = I_ 1. R 1 ( '2 7 . _ 9 _h _3 7 _ ! . 09 7 o ,5 W H .Q OOw l b_ 86h 9 5a • _= ? I r 3_.l 1 C_ Q . ? q _3 1 3 7 6" _ .1 P 5 9 . 1 bl . b UO_ b _ 7 1 1C9 q 5 _ _ == _ I n _ . _ l C p = . = 9._ 1 3 7 b = _ . 1 7 5 9. 1 6 1. _ C O , 6_ U 111 02 7 3 =¢o _ = n. ? I C P _. ? _ P ,1 1 3 7 b 5 _ . 1 2_ _ *C b l o * 00_ 6 e9 11 C_ E 8 _ " _ l _ . P Ir3_.i 9 _n 13 7 h _ k ,I_I I _ , 5 _9 ° b * O0_b h l 1 599 8 _ 3 Ratio Free Free Reyn o l d s _ Test S t ati c Stagnation Freon of Static stream Dyna mi c Freon number / ft stream po i n t p ressure pressure purity specific temperature Mach pressure velocity density free heats number stream Figure 11.- Sample Output From A.R.E.S. Data ReductionProgram. - I i
I
ORIGINAL PA G E IS OF PO O R QUALITY "_ _1 : 1 I C qP T EI _ F P R w ARO F LIG- I T P E R FC _MA NCF_ ( a AT A t _ = _ ":. 2 _ ] _ . _ 3 .9 c 9 ,9 2 .5 JI, 4 *l e l,l _ b _ ;,6 " 2 .1 1 " " _ = 5 "I"; ' 6 1 _ ' _ t"C ) 09'7 2 *R 2 7"1 "2 4" 4 _ 7 1 "7 " 2 " 2 _ 7 " 2 .3 6 17, _ _ ,, _ Q0 .6 5. _ 1%,*, " e. 9,1 301. _ "P*6 : ' _ -2,3 61 R . _ _ , 0 q 0 . _ 5.4 6 *3 "67. _ 3 1 U * _ - 2 ,6 _ ' _ "2,3 _ 1 _ * _ 4, 0 q 0 *6 5 *9 -,8 -73,B 3 16.6 " 2 . ,6 K_._ -5. _ 61 _ , _ 4, 0 _ 7 ,1 1 0 ,4 1 % ,; _ - 13 2 ., b 31 _ , 7 " 3, 7 Sha f t Rotor : T est angle rotation a l Coll e ctiv e Norma l Axi al Pitching R o ll i ng Yaw in g S i d e mo m e nt momen t po int of sp ee d, pitch forc e forc e ( hub) ( hub ) mo m e nt force .', e a tt ac k rpm Fi gur e 11 .- Con tin u e d.
l
?
_ . _1 . _ . _ _ ll .r *?. i .7 l . r *P I_ . _ 1, *o 3 bl l | .10 _ 17 a l * OlSl i_ . ou _|_t - *00|(. _ ..J _ 7 I.. )
(
" Shif t R o t or Lif t fo r ce D r ag forc e NO nN I fo r ce A x ial fo r c e S ide fo r c e To r_ ) _e _ co e ffic |e_ t / Roto r c o e f f i c i ent / c oefffc le nt / coeff| ¢ le ht / - e st angle rotatl o ea l Lat er al LongRvd l n a l _) lec ti v e Mvlm'*. _ h coe ffi c i e n t / m int o f s_e e d o C F I l c c y cl i c p.tch ra tio _ r so lid it y sol idity sol|dlt) soli dity sol l dl t ¥ s o l I d $ty _r s e_r k ett¢ck r m ret$o r l [l o *_t_) ratlo ratio reti o Fig ure 11. - Co ncl uded. ) 'l i I T O T 3 48 J AN / FEB 8 2 RUN N O 28 CHAhNEL NO 4 PT N O Hf . A N 1 /? P-P R PM IP Z P 3 P 4 P bP 6 P 7 P 0 P 681 38.13 16.25 638 11.ff7 5.28 4 .q3 1 .59 .09 .67 I g .71 A,.,P RHS 1 / 2 P-P= 1 3. 4 5 144 . c 1 31 B ._ . 3 354. _ 14 284.98 1 . _ 5 ' _ 9 5.77 2 3 2.8 8 73. 9 3 P;:' , SE 68;' 35,96 1 6 .7 9 64 9 11. ' 4 5. 17 4. c -4 1. 37 .69 . 6 2 IZ . 4 4 AHP R HS 1 / 2 P- P - 13.51 1,; 4 . ,.' 9 3 _ J9 .73 17. _ 3 29 7 .6 ? 75, b 8 3 ?- /4 . . " B 344. 7 9 93.1 8 P q ASE 6 _ 3 36.61 16.41 638 l B . 90 5.16 4. _ 9 1.61 , 4 6 . b4 14 .q Z _ . ' ? P _ f* , S 1 1 2 P - P- 13. 3 4 1, _ 4 .' ;0 3 12.9 4 3gG. , ; q 2 05.74 354 . . "_ ; 3 _ 1 . 2 4 ? 13. 6 7 7 7 . _ 8 P ; A ,'.E 604 36 .33 1 6 .70 64 ( / 1 1 . 17 5 . " 6 4. ' 15 1. 4B . b 5 .54 1 3 .4 9 AHP R MS 1 / 2 P- ? - 1 7. 52 14 Z .35 3_ .7. ' 5 1 _.?- 4 2 88 . 8 7 83. _1 7 31 _ . . $6 33 / . '. t _ 74 93 P i:ASI'. ' 6 _ 5 33.7 2 19.21 641 11,21 6. _ 3 4. 1 7 1.5 7. i.al . ' _ 15 .?. Z A) . ;P R, _ t S 1 / 2 P - ? - 14. £ ' 1 14 , .'r . 7 2 3: _ 0. , ' ,9 3 6.17 3 B 7.91 8 9 .7)' 3 1 3 . '3 33 7 .42 1 _ / 4 _ 4 P'fA S E 6 06 3 4 .] B 1 1 . 72 64 _ ' 1 _." 2 6. e f9 4, ;g 1.5 7 . 1. 4 8 ' .43 II .1 7 A M P R HS 1 / 2 P -P' . 13.5 7 14 _ .4 2 3._ I ._ I 3 1., _ '_ 3 _b .50 C_ .9 5 3 1 1 1.13 344. _ 9 1 "7 .b7 PI:, _ SE ( _ B7 34.19 1 7 .51 6 9G 1 B ." 4 6.1 3 5. t , 3 2 .2 _ r 1, 7 6 . %_ 4 18 .17 A HP ' * _ , _ ;S 1 ,' 2 P-P" 1 4 . _3 141.. _ 3 3( _ 7.;4 2 0. 2 '3 29Z . 4 9 5r , . 1 5 . t0 0.5 ' _ 3 5 1 .1 2 B'; b7 PI l A tE , ' 6_ 8 3.].97 1 7.9 3 b9 3 l g , l b 6.54 5.,*4 2.# 3 1 .74 . ! ,Z .1 7 . /.7 A;'tP :. % Figure 12.- Sam pl e O u t pu t F ro m A . R .E.S. 1 4 H ar m onic Ana lysi s P r og r am . __ w
ORIGINAL PAGE IS
OF POOR QUAL I T' : [
. C LIo = 0.075, MT = 0.65
15-
O scillato r y 1 0 -
t ors i onal / S o f t
• mome nt / I /,, . _ Sti ff
at 5 2' / , rad i us,
in-lb 5 = . . _ _ _ . _ . . _t
0 ., I I I
• 4 --
S oft
Figure 13.- Param e tri cT ip Shape s for I / rev
C o nf o rm a b l eRot o r Test s . fla pp i ng a ng l e , 2
d eg
I
-- Stiff
0 I [ J
30-
) 40 . 8 1R L / So ft : ,
mome nt _ / "
at 26_ r ad ius , 1 0 " /
60 in - Ib - " /
1 / 2 P- P 20 I 0 _ - I I "_.
flapwi se 0 "
mo m e nt 100 - Soft
at
s tation , 6 0 F .39 R 8 0
in - Ib 4 0
0 Ljj i lll} JI
0 l / rev 6 0
normalforce ,
. Ib 4 0
' 20 1111 J _ _ 20 sti ff
0 s
Be st _ Worst -- - ' _
- " T " i I
P erformance rankat CD / O _ = -0 . 01 1 0 0
o l o 2 o_
P
Fig u r e 14,- C on f o r m a b l e Ro t o r Lo a ds a nd F ig u r e 15. E ff e c t o f 4o T a b De fl ec ti o n on To r s i ona l l y Perf o rma n ce . S o f t a n d Stiff B l a de R esponse . _ ' 15 , _ i
acceleration , . 2 5
Frequency, 4 Body rol
g 0 Hz 3 _ _ ' , -Rotor l ead - lag
6 o Ba se line 2 f r e gress i ng mode
• 1 / Ve r tical . 4 OWith HHC o - , , , , , ,
ac c e l e ration , 8 _ Analysis
g 2 R eg ressing o o Ex p e riment
• I _ m od e 4 o o ' 0 dampi ng ratio .
percent 0 • 8 - critical Jn .6 "4 300 , _ 00 _ 0 600 700 800
• a cceleration, .4
g 2 F,gu r e 1 9 . - C omp ari so n o f P r ed i c t ed a nd Me asu re d : • Stability a s a Fun c t i on o f R o tor j Sp ee d t n H ov e r.
c t e r ,
0 .2 .3 .4
. Advanc e r a tio E xp e riment A nalysis D roop
!
• 4° _, F i gu r e 16.- Ef f ect of H ig he r H arm on i cCont r ol • ...... 2 0 on Fix e dSystem 4 p V ibration Lev el s . • -2 ° S / Ib s N / " • 35 - 1 6 0 R e gressing4 . / " / !
la g mod e / f , , } 0 - d a mpi ng ratio, 3 . ," • ) 25 - 1 20 " Optimum " H H C ' _ j _ f \ y _ / pe r ce nt , = / f / -/ . , / _ J pit c h l inklo a d , 80 _- Bas e hne Alte rnatin g 2 0 _ . y , , _ , _ 3 " _ , '1 c ritical 2 _ . .. _ . ._ ../" ;,
,__.._/ •
IO- 40 i i I I J I 5 - 0 2 4 6 8 1 0 1 2 ' _ 1 / 2P - P 15 - t "_ ] L -- % L J J I I t ( 0 - 0 .2 O . 25 . 30 . ) 5 .40 .4 5 Coll ec tive pit ch ,de g Advance r atio Figure 20 .- E ffect o f Bla d eDr oopAng le on Lead- L ag Fig u re17.-Variati o n of Alter n ating PitchLink Dampi n g at A dv an c e Rati o= 0 .30. " _ Load (I / 2Peak-to- ° eak Values) With Adv ance ratio.
Ex pe ri m e n tAnalysis Pre-cone • 3 o • ...... 6 o Reg ressi ng , Jl l ag mod e 3 // da m ping rat i o , m . .- / i • pe r c ent 2 _ " critical 1 i I I . . . . . 1 J 0 2 4 6 8 I0 1 2 Co! l ec tive pit ch, de g [ Fig u r e 2 1 .- E ff e ct o f Blade P r e-Co n eAn gl e o n L e ad- L a g Dam pi n gat A dv a n c e • _ F igure 1 8.-Mo d elHinge l e ss R o t o rHub. Ratio- 0. 3 0. ' i
___ J
Figure 22.- 0.2 Scale JVX AeroelasticModel.
In i t ia l t e st Seco nd test update B as ehne -- -- 0 --- New sp ar ( S ) --12}- - S + stiff b ide s ( SB) S + SB + conllx j hinge hu b O n do wn st o O (I o ctedl Off dow nstop ( unlocked _ !
. o r- q o
J % nomina l 90 _ ', } 8 0 J _ I I I ___t_ I -C , . 9 1.0 l . l 1 . 2 1 .3 . 1 .8 .£ 1 . 0 1.1 1 . 2 i -- Vfl utler / Vref Vfl utter / Vre t F i gu r e 23.- Expe ri men t al Resu lt s of JVX - Model Wind Tunnel Tests.
.| -i
,k
i
" ____
I ,r ' i I. R e poc t No. HAS A T M -864 4 0 2 . Government Acces s ionNo. 3. Re c ipient' s C ata l og No, USAAVSCOM T M 85-B-5 4. T it le and Sub t i t le 5 . Report Dat e June '1985 AEROELASTIC MODEL HELICOPTER ROTOR TESTING IN T HE S. P e rfor min g Or ga niza tion Code LANGLEY TDT 505-42-23-05 7. Author(s) 8 . Perfoc m i ngO r ge ntz a tion Report No.
Wayne R. Mantay, William T. Yeager, Jr., M-Nabil Hamouda, Maj. Robert G. Cramer, Jr., and Chester W . Lan g ston io . W or kUni t No.
9 . , ., P er focming O rga r ', a ti o n Na me and Address I _l : ructures . .aDoratory AVSCOM Research and T echnol o gy Laborat o ries 11 . C ontract or Grant N o .
NASA Langley Research Center !
Hampt o n, VA 23665 1 3. Type of Repo r t and Period Cov ere d t
12 . S pon s or,ng Agency Name and Addres s Technical Me morandum
National Aeronautics and Space Administration • !
Washington, DC 20546 14A r my Proje c t N o . - " U.S. Army Aviation Systems Command St. Louis, MO 63166 lL162209AH76 i 1 5. S uppl e m ent a ry Not e s Paper presented at the AHS Specialists' Meeting on Helicopter Test Methodology, October 29 - November i, 1984, Williamsburg, VA. _ 16 Abstract i Wind-tunnel testing of a properly scaled aeroelastic m odel helicopter rotor is considered a necessary phase in the design development of new or existing rotor systems. For this reason, extensive testing of aeroelastically scaled model rotors is done in the Transonic Dynamics Tunnel (TDT) located at the NASA Langley Research Center. A unique capability of this facility, which enables proper dynamic scaling, is the u s e o f Fre o n as a test medium. The paper presents a i des c ription o f the TD T and a discussion of the benefits of using Freon as a test | medium. A description of the model test bed used, the Aeroelastic Rotor Experi- ! mental System (ARES), is also provided and examples of recent rotor tests are I, cited to illustrate the advantages and capabilities of aeroelastic model rotor i testin g in the TDT. This paper de m onstrates the importance of proper dynamic scaling in i dentifyingand solving rotorcraft aeroelastic problems, and affirms the importance of aeroelastic testing of model rotor systems in the design of advanced r o tor systems.
,I ?
1 7 , Key Words (Sugges t ed b y A u thor(s)) 18. D is t ribut i o n S t atement Helic o pters Unclassified - Unlimited _ Wind tunnel Aeroelasticity Subject Category - 39 | -, 19. Sec ud ty Class i f . (of t h i s rep ort) 20 . S ecu rit y C l ass if. (o f this pa ge ) 21. N o . o f Pages 22 . Pr ic e' i Uncla ss ified Unclassified 18 A0 2 • For sale by the N ational Technical Information S e rvice , Springfield, V ir g ini a 22161 ...... lm