ANKA-1 micro-helicopter design and development project

ANKA-1 MICRO-HELICOPTIW.

OESIGN ,c\.ND DEVELOPMENT PRO.JECT

Y. K Yii!Jkci I . Ill· /urkn. D. P Scilmgc2 I ;,I rt·J 'II.

''!". Ugur1 and S. Yuksct1rn · Furke.1·

Ahstrart

I S.l

Conceptual and initial design of a X70 Jb mtcro-hclicoptcr has been comp!ctccL Stead_\' state forward flight tritll

equations me dcri\"(~d for the compound helicopter configuration \\'ith canard/tail \\'ings and horizonUJI tail propulstotL Blade loads me calculatccl for different nwncu\cr loading and vclHclc configurations. Helicopter fuselage and rotor blade arc modeled usl!lg IDEAS program. Composite rotor blades arc clcsignccl and ;maly:;,cd

b\ IDEAS and blade tnnlstcnt responses arc sunulatcd b! solvmg rotor blade panwl cl!ffcrcntwl cquatiOll-" b.' ;1

conditlo!l<lllv stable c:-.:plic!l finite diffCn.:ncc lllcthod.

1-INTROOUCTION

.ANKA-1 Micro-helicopter project lws been initi;ltecl as an uni\crsi\~ level design and development project b~

Istanbul Technical Uni\·crsity. Faculty of Aeronautics and Astronautics <lllcl CJco1gia Institute of Technology.

Schoo! of Aerospace Engineering in cot\iunctJOU with ong01ng unfunded cooperative b:1sic research studies

related \\'ith !lap controlled rotor blade and stopped rotor concepts. Primary obJcctt\'C of the proJect ts

establishing bnsic rotary \Ying rcscarch-clcsign-clcvc!opmcnt capabilities at Istanbul Technical University.

As bc1ng the first stage dcYc!opment or <t demonstrator <·llrcmft the aim is to stimulate further research and

design efforts ror the dC\'Clopmcnt or a Itt!! prototype. Project currently has received <1 lilllited funding from State Planning Of'ricc or Turkiye and ;\NKA-1 Project has already started capturing natiOnwide in!erest as

concc:ptutll design studies and a full scale mockup have been completed. ~_fg.!~!.l..<.~L~.1Js_!:Q:J~!J_~Q.P_tJ~L.~tH!

..

i.~JJ~·cattt1

Today's pnvate transportallon has gone about as far as it can go on the ground <lncl micro-helicopters will

answer the needs of Jndiv!duals who want to travel pol!lt to pomt W!lil less dependency on ground

trt~nsportation tnl'rastru..::turcs As recently rev!Cwcd by Drees tl J smalL low cost helicopters wi!! be one or the

new and ch;;litcnging mea of' helicopter technology by the cntr) or the 21 til Century. As pointed by Drees r I J

shortly after the World War fl. lWlll\' or helicopter designers had a \"ision that it would be pOSSible to design <l

helicopter lOr e\·crybody. cas~· to 0!. atTordab!c. tlllci safe. 1-!e!icoptcrs \dlh bigger S!I.CS haYe found wick

acceptance in the aviation \\Oriel but nothing signilicant came out !Or the small ones except the two-seater

Robinson R-22: \\Oriel's most populm smallest certified ci\'i! helicopter. Arter a decade several designers hm·c

stmtccl to ask \\hcthcr a small persona! helicopter is still an impossible dream or can it be rcali;.cd \\'ith todw·;'s

knO\\·-ho\\' ;mel technology? CJrmdng in teres! for smalllrnicro-hclicoptcrs and number of design. and prototype

clevclopmcnt studies arc believed to be the C\'ic!cnccs of the possibilit~ of this dream 10clay

l'ABLF- I shmvs the list of I -2 scat nucro-he\icopter design and dc\'clopmcnt studies. most or whtch htl\·c

started dunng 90's. Computer <udcd design and advanced composite tcchnologtcs arc now maktng it possible to

clcsign. clcYclop and nuwuH1cturc small ll.':cd \\'ing aircraft ancl snw!l helicopters e\'Cil by relatively stn<Ill

companies and design groups. GrO\\'ing need and interest for personal transportation ,·chicles which can give

individuals the uJtiJmJte f'rccdom of traveling from point to point is the HU\)Or !1\0tivation these behind design

crrorts. Micro-helicopters nrc expected to be the motorcycles of m·int1on by the 2! st cent or~.

Major objecti\'CS or micro-helicopter designs can be outlined ns easier ancl s<l!Cr to

n,

helicopters \\'ilh raster

speeds <llld increased rtlllges. These capabi!ittcs arc needed to make micro-helicopters more compatible with

cx1sting small fi:-.;cc\ wtng ;urcran. Simplified controls arc needed for these I) pes of helicopters which <Ire

currentlY more difficult to ny then fixed \\'IHg ;urplanes cmd carlike controls for an easy to n~ helicopter 1s

essential \\'here all controls me spnng !oacled and returned to center after rorces ;Jrc remm·cd. It is belie\·eclthat

today's nc\v gcncnillOII or aclnmccclmJcro processors can 1mpement the control lm\·s required to make a

lllicro-hcllcoptcr as cas~ tony <lS driYlltg a em.

1

.\.o.;.'<\. PrPL; h11.:ul\\' of..-\cronauliL·s 8: . .'\S\!'1'11<1\IIi~·s: J:..tanhul Tc::dH\Jc:<d \ 'nn\::rsitY; Tud,c:\' '2 l'rokssor and l)il·~dor of ('1·:1{\VAI' & I-"!.!(; I!'!" Sl \IS: School nl· .-\CI'PS[J<\1..">.: l·:n~;itk·c::rin_;;: (,lc::nq;.1a !n:-.lilutc:: ofTc::l'hth)logy

Today's advanced and highly automated guidance and control systems have significantly c;;lscd the remote

piloting of Unmanned Aerial Vehicles. 1t is now possible to remotely control UA V' s by simple commands as

take-off .climb, tly. turn. descend: like playing Atari games. Several guidance and control hardware and software capabilities originally developed for costly military projects arc now becoming available for civilian applications \Vith highly reduced prices. With these technical development micro helicopters arc no longer a dream.

Table I. Micro-Helicopter General Information

Design Vmax Range Ceiling Pm..-cr Wcmpty Wgross Rmr

knots nm ft shp lb lh ft CH-7 Angel 86 205 11000 65 374 682 'J.S Ultrasport 254 55 70 55 252 525 l 0. 5 Prop. Koptcr 60 200 8500 30 155 650 120 Homcbuilt Hcli. 65 200 7000

40

300 800 12 Sky Bird 50 75 12000 40 !50 350 8.75 Sky Sport 74 150 12000 60 300 575 9.5 Exccll 2000 100 200 10000 150 820 1420 12.5 Baby Bell 100 200 10000 150 900 1400 12.5 Commuter II 100 200 150 700 1300 12.5 Cobra 100 200 10000 150 750 1400 12.5 Predator 95 150 10000 95 450 900 9.5 Skylark I 95 120 12000 65 350 700 9.5 Heli~car 100 125 12000 80 300 650 7.5 Mini 500 95 225 I 0000 67 330

no

9.5 Exec 90 115 [8(1 10000 150 925 1425 12.5 Loncstar 90 1 15 10000 66 370 680 10 Capri l 1 () 555 150 705 1212 10.65 Anka-1 130 520 12000 100 450 870 8.0

One of the particular important aspects of future small rotary wing aircraft development is the need for nc\\ power plants. New developments in rotary engines, diesel powered C!lgincs and especially high performance mass produced light \Veight automotive engines are quite promising. Ne\v technologies opportunities and grmving demands have motivated designers and several concepts for small VfOL aircraft have been

introduced. As an example: the concept of a small tw·in engine personal helicopter as suggested by Drees is

shown in Figure I. A conventional main rotor and tail rotor configuration with very innovative and futuristic

airframe design. ANEX reflects these expectations and imaginations. ANFX designed by industrial designer

Peter Ncwrnann in Germany is also shown in Figure 1.

The first objective of ANKA-1 micro-helicopter project is the development of a small commercial helicopter. Second objective is more research oriented towards the development of a proper tcst-in-tlight helicopter for the validation of flap controlled rotor blade and tip-jet stopped rotor UA V applications. Results

of several initial configuration design and fundamental research studies have indicated several overlapping

(common) design futures for both configurations. Stopped rotor configuration required the utilization of

auxiliary lift and fonvard propulsion devices such as nose canard and tail wing as \Veil as vectorizcd tail

propulsion for anti-torque and horizontal fonvard auxiliary propulsion. This design features can also be

utilized to make commercial a 1-2 seat micro-helicopter fly faster to reach longer ranges. Related research

studies for flap control are also promising for the achievement of advanced control mechanisms even complete

replacement of conventional pitch controls primarily

ror

a micro-helicopter weight thrust range (2.3j. Flap

controls will also give capabilities for wide band controls which can make possible higher harmonic controls (HHC) and individual blade control (IBC). With these new technical developments and design features_ it is believed that highly a stable. agile and easy to fly commercial personal helicopter can be achieved.

2-CONCE.p~J,:_IJAL AND INITIAL DESIGN STUDIKS

Vehicle Configuration

For conceptual and initial design studies, steady flight trim formulation has been derived for a compound

helicopter configuration with canards. tail wings (vertical and horizontal) and fonvard tail propulsion.

General configuration of the vehicle has been illustrated in Figure 2. As the first step longitudinal force

utilization. Conventional trim equations given by Johnson (-1) have been modified for new the vehicle configuration well as for the rotor system \Yith Oap controlled blades. Details of vehicle trim formulation arc given in Reference (5). Tail propulsion. Tpr is assumed to be acting parallel to the main rotor reference plane. For trim calculations helicopter fuselage aerodynamic drag is taken as:

l

'

D =

---pv·r

2

where f equivalent nat plate drag area of ANKA 1 helicopter is approximated as

.,

f= 1.0 + 0.4

u

+ 10

a·

Total auxiliary lift is non dimensioned as

vvherc

_{JC<I~~--~·-f.l~

plrf('Q'

Variation of auxiliary lift coefficient with respect to forward flight velocity is taken as:

C

L :::::

C

'Tt:rm .

"'V'

H

- C I I f d ! 'l . '' - '

2

-r;/2 _{( '}

_{-2 '}

_10·8 _{I , , 'I•- ,}

-tor .-L = 0. 9 anc tota area o. canar anc ta1 wmg .• ) TOT -- J. ·' , !can ·~· , ,). . n d sum di man net auxiliary tail propulsion is formulated as.

c·pr

=

C

tprop X

y~

and initial design value of Ctprop is taken Ctprop'"

0.

45x

lo-s'

VH

is vehicle forward speed in H!scc a series of trim calculations arc performed for initial design and primat)' design parameters of the selected configuration arc listed in Table 2.

Wg ~ 870lb Rmr '" 8.0 ft

Crnr

=

0.52 ft Number of Blades"' ] Clmr '' 76 .rad/scc

Table 2. Baseline Design Parameters 0 '~ 0.089 y "' 6 Otw ~ -0.12 rae! C:tcan '' 2.5 E-8 Ctprop '' 0.45 E-8 Xcg = 0.125

n

Ycg~oo

n

h ~ 2.4 ft Ltw ''' 9.5

n

Ltr ,, 10.9 ft Lean= 4.7 ft

The cfTcct of canarcVtail wing lifts along with the utilization of tail propulsion on main rotor required pO\vcr have been investigated. Figure 3 shows the variation of required rotor shaft moment versus forward speed for different maneuver loading both for the compound and standard helicopter (without auxiliary lift and propulsion) configurations. Significant reductions in power required have been obtained for the compound helicopter configuration primarily at higher speeds. Utilization of canard/tail wing lifts arc also reduced the amount of collective pitch control inputs as the forward speed increased is also shmvn in Figure J.

Initial design studies has indicated the advantage of using auxiliary lift and tail propulsion. Studies arc

currently extended to\vards more realistic approximation of fuselage drag particularly: for d.iffcrent vehicle

angles of attack. Since the fuselage drag has increased with the third power of angle of attack which is reduced by the usc of tail propulsion less fuselage drag is expected for the final configuration. Aerodynamics of the canard fusc.lagc combination in forward fhght are being studied by Gulcat and Asian (6) solving the full Navicr- Stokes Equations numerically. A finite element method (FEM) with an explicit time marching scheme is developed to calculate drag lift of the Anka-l helicopter canard fuselage combination. CFD calculations arc performed around the fuselage with the grid system shown in Figure 4. The velocity vector over fuselage canard configuration about the mid span on the canard arc also illustrated in Figure 4.

CAD and St•'l!'CU!ra_LModeli!!J!:

Advanced computer aided design capabilities is one of the key' assets for the realization of advanced rotorcran

design and development studies. CAD model of ANKA-1 helicopter is modeled with IDEAS package (7)

program and initial layout out of fuselage and tail boom is shown in Figure 5. TDEAS package has been also used for static structural analysis

Rotor loads arc ca!culntccl based on rotor blade dement Ycrtical and in plane force formulation. Resultant blade distributed force Fz acting vertical to blade rotation plane nnd in drag plain force Fx arc written by the usc of t\"vo dimensional strip type aerodynamics and integrated along the blade span. Rotor thrust and required shaft moment arc calculated by averaging these calculated values over one blade revolution. Rotor loads arc calculated for different blade azimuth positions to find the maximum loading condition. Typical blade vertical force spanwisc distribution is shown in Figure 6 for different maneuver conditions up to vertical acceleration of g=3.0 and for standard and compound helicopter \Vith canards. As seen from Figure 6, blade loads arc reduced \Vith the use of auxili<liY tift which cased main rotor thrust requirement.

A graphite-epoxy based composite blade has been designed for the calculated maximum blade loads and deflections oft he designed rotor blade under maximum static loading has been shO\vn in Figure 7.

Rotor blades designed for maximum static loading arc also checked for their dynamic responses. Non

dimensional blade stiffness ::1.re approximated for Anka~l blade as~

E!

A,

=-~;'-;''0.00356 mQ-R1 h

El_

i\,

= ---;' -- =

0 0486

-

m

_h

nir'

Anka-1 rotor blade transient blade responses arc simulated by solving nonlinear clastic blade equations \Vith a conditionally explicit finite difference scheme introduced by Yillikci and Hanagud (8). Blade required control inputs calculated by trim formulation for increasing forward flights conditions arc illustrated in figure !0 where forward speed has been increased by 6~t = 0.025 increments at cvC!)' l blade revolutions. Figure 8 also shows ANKA-l rotor blade lead-lag, flap and clastic t\vist responses respectively. Blade response simulations studies have given promising results for the initial blade configuration.

,>-FINAL EVALUATION_

Conceptual and initial design studies of Anka-1 micro-helicopter have been completed \Vith above clcscribecl studies. Overall weight. dimensions and performance estimations arc as listed in Table 3. Future goals of Anka-1 design arc set as maximum cruise speeds reaching 150 knots and maximum range around 650 nm along with highly automated pilot friendlY flight controls. With cnrrc:nt limited funding de\elopmcnt of a demonstrator helicopter \Vith design goals listed in Table 3 is planned. Anka-l will be developed to be a one-seat high performance helicopter which can be also flown as a t\VO scat helicopter for shorter range. Three view of Anka-l helicopter is shown in Figure 8. A full scale mock~up of the helicopter has been also built by the design group which is shown in Figure 9.

Weights Max Take-Off=-Empty Weight= Fnel Weight '' Payload= 870 lb 440 lb 2!0 lb 220 lb Number of blades,, l

Table 3. Anka--1 Micro-Hcl.iroptcr General Description

Dimensions Performa~)CC

Length ~ 16.8 ft Max cruise~ UO knots

Height., 6.25 ft Normal crnise ,,. 1211 knots

Width " 1.12 ft HOGE

=

70011 ft Rmr ~ 8.0

n

l-llGE ,, 911110 ft Cmr = 0.57 ft Acl<nowlcdgmcnt Ser\iee Ceiling " 12000 ft Range'"'"" 520 nm

This work has been supported by State Planning Office of Turkey under contract 94K 110270 and the authors greatly acknowledge Dr. Kemal Guice. R&D Projects Coordinator for his supports The authors also wish to thank Y cs1m Korkmaz and O~:gur Turkgenc for their help and participation in the project.

References

1- Drees, J.M "Prepare for the 2 I st Century-The 1987 Alexander A. Nikolsky Lccturc11

, Journal of American Helicopter Society, Vol12 No 3 pp 3-14

2- Yil!ikci,Y.K: "Trimming Rotor Blades With Periodically Deflecting Trailing Edge Flaps!!, .17th European Rotorcraft Forum. Berlin, Germany. 24~2() September 1991

J- Y.K. Yit!ikcL S.V. HanagucL D.P. Schrage and J.P. Higman: "Acroclastic Analysis of Rotor Blades with

Flap Controls". 18th European Rotorcmft Forum, Avigno, France, I 5- i8 September 1992 4- \V.Johnson: Helicopter Teary', Princeton Press, IlJSO

5- Y.K. Yillikci: J. V.R. Pnrsacl and D.P Schrage: "Transient Response of A Flap Controlled Stopped Rotor. "ICAS-94-5.8. 1, 19th I CAS/ AIAA Cotlference, I S-2 September I 994, Anaheim. USA

6- U. Gulcat and A.R. Asian: n Drag and Partial Lift Prediction of A Helicopter Fuselage with A Canard Using

CFD11

• Second European Computational Fluid Dynamics Conference. 5··8 September 1994. Stuttgart. Germany.

7- IDEAS. I-DEAS Solid Modeling and I-DEAS Finite Elements are trademarks of Structmal Dynamics .RcscHrch Corporation.

8- YillikcLY.Kc Hanagud,S.V. "finite Difference Tecniques and Rotor Blade Aeroelastic Partial Differantial Equations An Explicit Time-Space Finite Element Approach for P.D.E." Presented at !5th European Rotorcraft Fonun, Sept. 12-15, 1989, Amsterdam. Netherlands.

FIA MAST TILT

TWIN

PACIC_/~\

ENGINE

~"---CAR

LIKE CONTROLS AND COCKPii DIGITAL, l=L Y BY WIRE CONTROL SYSTEM

Figure 1. ANEX futumstic helicopter study by Peter Naumann. and concept suggested by Dress rRej' 1)

T _{MR ;} ~a _s

v

8FJ>

'

_I r· 1 _a o.s

\.

~~--.I h C<tl1 -~

Figure 2.

E ::Oil :::;;.: ..,_.,ISO .• ,,__ ' ~ QJ_;

•

i

o-!--o

•

-I

,

1 I M -< r -"can!

y! 'i'Pr

\

-f~·~

I

I

·A ..

"tn ·

t_ i can ' _l 'X _(.g

w

' \-! can

-\-H <:.: o.:.:r~ >

..

~ v o.::o GJ I tw L -~-tw. -i~--r··

. '·'-o

tw .TJlr_ . I ' - - () ; () - .. , r .-, ., . .,. •. -,-~-,-- . ''" ,--100 !50 :coo o :'"JD 100 1f10

F'orwc-trd Spe('c! (knt:-::) Fon .. vnnl Sp(·c~d (1<:11!.:.:-;)

Figure 3. Effect ofauxiliat)' lift and propulsion on rotor power and collective required.

Figure 4. CFD studies of ANKA .. l micro helicopter.

I··DEAS Maste:o: Series 1.2:

0.-.tn.bll.!le: /usc.r!l/ s6.hinl/o.nka .rt~!1 Viaw No ~<torad View

,.---···-···· ...

·--1

Design

Figure 5. CAD modeling of Al'l'KA-l with IDEAS package program.

~ ~

,,

""

-·

if. i5 0 u ~ 0 "-400.0 :.300.0 200.0 CHH'!-Q-8 ~­ <o-.;>-V-t)-{) --::l-1:<-~

1•·HH

'

Azimuth Position Std. H/C g:::::2.0 0.0 deg 45,0 deg 135.0 deg 225.0 deg 270.0 deg 315.0 d<lg ,0 0 _200.0 150.0

Azimuth Position =135 (deg}

, OO<iHH) Cana.-d H/C g::::1.05 j 00-{...,Hl Std H/C g::o: 1.05

1

"'

t:.-.h"".rl:""- Conard H/C g=2.0 ****""" Std H/C g:::2.0 -~-"-•-+-• Conard H/C g=3.0

ll

~_.,_,._...,Sid H/C g=3.0

Figure 6. Blade loads calculation for standart and compound ANKA-l configuration.

/ u s e r s / a n k a l / s e l i m / p a l b l r mfl RO:SU[..'TS· 2- !3 C. l.LOAO l.S1'111'.:SS_2

STRESS- t~;..x ?ll.Hl MtN:-2.01E•08 ~!,\X: 2 J.6~:-•C9

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O!SPLACEHEN'!'- Y tHN:-6.46!t·05 ~!AX: 7 6'5£-?2

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y

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Figure 7. Composite blade static deflection analysis.

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40 so ao 1 oo 120 , 40 l60 1 ao 2oo 220 2.40 2&0 zso 3oo 320 34C

Blade rotation (rod)

-o.os

t',..,.,.., .

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Blade Rotation (rad)

0.10

0 .oo ~,...,.' H'"SO'""'"'"'.,-' ,...,.8'(i'"'"'"n

,v•roo""'"r

r ' ,..,..,rfO"''T'"'"'i'~o· .,., .,.,.,y1o

;ro·n·· ,.,..

'tAO ,..,..,,.."2.()()'"' 't'trt"t2 2Q'"rn·•n:rlon..-.·.-..-.2 ~0'""'''"'"'"'"'28"0-ro·YC>"'30'0"~"rrrT.,..310

Blade Rotation (rad)

0.02 -:;;- o.oo 0 .

-'=-:~ -0.02 ,__ 0

"'

ti

-0.04

w

-0.06 .:}.,.,-.-,.,.,..,...,..,..,.,.,..,..,., ..--rr,..,-r<"r,...,.,.,...,.,.l""f""O""r>"o·r<·cr,-•"1 T ,-.,.,...,-,., ,.,.,.,.,.,., .. ,., .,.,.,.,.,.,.., • .,-r...-,·.,-rcrn ,.., . .,.,.,.,.n ,., ·r,.-,--rrrn•.,-o·n·p·ny-,.,,-,.,YT>">"<·...-.·r '"'"'"""'"' .,., . .,.,.,..,.,.rr,-,-,.,...,..,,.,.,.,..,-TT"Trrl 40 eo ao 100 120 uo 160 H!O 200 no HO 2GO 2so .lOO :s2o 3-IO

Blade Position (rad)

Figme 9. 3 view of ANKA -1 micro helicopter configuratiolf.

y

Figure 9.Full scale mock-up of ANKA-lmicro helicopter. 9