This report contains artificial aerodynamic characteristics of a set of propeller sections to be used in designing propellers by means of the blade element theory. Characteristics computed from model propeller tests for a single section are extended to cover sections of Navy propeller sections at high Reynolds Number in the variable density tunnel of the NACA

Weick, Fred E

English

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52244
TECHN ICAL NOTES
!'TATIONAL ADVISORY CC%[MITTEE FOR AERONAUTICS
_c_ -T_
No. 244
I_bIVY PROPELLER SECT!01[ O_uAEACTERISTICS AS
USED IN PROPELLER DESIGN
By Fred E. Weick
Langley Memorial Aeronautical Laboratory
Reproduced by
NATIONAL TECHNICAL
INFORMATION SERVICE
U S Department of Commerce
5prlngfiefd VA 22151
Washington
August, 1926
J,3
https://ntrs.nasa.gov/search.jsp?R=19930081052 2020-03-17T04:23:10+00:00Z
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ITATIONAL ADVISORY COL{,:I!TTEE FOR AEF,OI'_7.'\UTICS,
TECt-2IiCAL i_CTE !_0. 244.
I:,AVY PI!0IILnZR SJJOTS0!_ C}L%R%CTERIST!CS AS
U2-iD "_[i_ _:T.CPELIE--t i)i]SItZJ.
By Fred E. Weick.
Sulnma r y
This reoort con+.ai,zs artificial aerodynamic characteristics
of a set of prop,ciTer sections to be used in designin_ propel-
lets by means of ti._cbla:te element theory. Characteristics com-
puted from model propeller tes%s for a single section are ex-
tc,:,C,::dto cover sections of all thicknesses by means of model
win<] _- _'"-,_,_,_on a series of Navy _ropel!er sections at hi_h_= Rey-
nclfs Number in the variable density tunnel of the Nation_l
Advisory Committee for Aeronautics.
Int r oduc t ion
Desig-nin_ proT)oiiers by means of the blade element theory
requires the knowledge of a,_rodTna.mic chzracteristics' which tru-
ly represent the airToi! {,,_tio:-_s. Airfoil characteristics ob-
tained frc,:_ wind tun_tc! r._od,el wing tests arc often used for
lack of better ".nform:_,tlon. These, i-owover, are not directly
a_icable to sec_n_s of rcvolvino orcosiicr blades. Better
results are obtaiDc_i by using characteristics that have been
calculated from mode! propeller tests. Such characteristics have
NoI.C.A, Techuic_! Pote }_o. 244 2
been d _ocrmincd for a limited number of sections (Reference S).
•n_i' rare extruded to cover ssctions of all practicable
thiclu_es_.es by means of r._c_e! wing tests on a series of l_avy
prope!Icr sections (Referense I).
These tests were made in -the _sriable density _rlnc-_tunnel_
of the Kational Advisory Committee for Aeronautics. The sec-
tions were tested at two tank pressures, one atmosphere and
twenty atmospberes, the i£%_oids Number at the latter pressure
.... -_ ..... _mL<,, found, in ._rope!iers. The
shapes of a il _6b_ess.'_._s.s _re derivel from a standard curve
(Fig. S) in such a _s_n_cr that the r_;£t-o of correspondin_ ordi-
nates to the _s_aximum ordinate remains ti'e s_<_.e. The cambers or
maximum ordins ted'.in terms of the chord of the six sections
tested were, .04_ .08, .IO, .12, .!6 stud .SO. These cover the
_ound in propellers Aran_e of z=._ f:_eed sections u__.._l!y
camber of .04 is s!igh_ly less th_.n is used in She thinnest
metal propellers at the prasest time, a_d .20 is about the ca_<-
ber usually found at half the radius in wooden propel!crs.
These sections, sometimes sl___._-_tl_:_,___ modified, have bccn ,._ide-
iT used in propellers in this country m_d abroad. This reoort
gives their aerodynamic characteristics as propeller sections
to be used in the bi'£c element theory.
t. _ecl_mioal 17eta No. 246 .%
Scale Elf oct
Consider an ii ft. propeller of average wooden constmlction
rev olv in_ r__ '. .... ,_14c 1800 revolutions per r:_inu_e .... e most effective
sections, those from about 60 to 80 _er cent of the radius, are
opera.t_ng_:_at a P.eynolds IT<imber of about 3,600,000, which is
the same ;;s %hat of _u(. _>]..o_c.l!er sections testeu at twenty at
mosphcres. N_a_ the tfp of the prcpel].er "_ '_no_ at about half the
radius the Reyn<Cds lf_v_:berdro0s to approximately 3,000,000.
Fi9;. ?_ sho_.rs a sot of CL and CD curves at ]. and _0 atmos-
pheres for each section ,_o" _-_ ,.t ._ed. Over t ",vorkin< ranc_e tee
_o_ ..
curves .Lo._all but the thickest section lie quite close toT5ether,
• %?_I," 7. "7in<iica,tln_r tha_ the scale effect with change of Reynolds _ _r
i_ _,,-_,di;'ib]e. TLe tests on the thickest section show a l,--_,,_
decrease in both the lift and dra._ coefficients at the hitcher
Reynolds }Tumb or.
It is _nown that when operating i_ propellers, the lift and
dra T coeffJ.ci ..... _-o • f... of a]r._o_l sections increase as their s-cecal
rela-_ive to the air __s _.=.,reascd, and this increase becomes
greater aq the velocity :_tproachos that of sound (Reference 2).
. _,.u_.,ber _cn_s to decrease theseSince inc_'easin_, _,_..e ilev-_al@.s '-_-
coefficients where i _ affects them, a,t all, it foi"_o_,,_......_-_ this
increase in the coefficients must be due entirely to the compres-
sibility of the air.
ii.£.oC.:k. TochnicaT. !_To%e No. 264 $
Propel!el _ Section Characteristics for Use
With the Blade Elcnent Theory
Airfoil cha_:acl-e:ristics obtained from wind tunnel model
win_ t e_s are not ,__..'cctiy" a_o!ics} _._ .... .._.c to airfoil sections in
a propeller, for the c,_._.'.i=cionsof operation are quite differ-
ont, The model a.irfoi.-._s_rc <Tsu&l?.y rectan_lar in plan form,
the cbaracte-_is.%ics m___surod %ein_ the average for the whole
span. Sect'.ons in _ro,_el!crs usually v'ary in chord and cambcr
along tl:o radius, a_zd _.... i_f c__,-_.,,_erzs%ics as u,_cc'.in_li_ a ....,oil ....'- .. .... " "
the blade _-!ement theory apply to an infinizely small clement
of the s_an. Fu .......
_ermorc, as Dr. !,iunk of the staff of this
C<._r_ittce has pointed out, the centrifugal effect on those par-
ticles of air which come in co,!tact with the re_oiving b!adcs
m_'_y cause a difference in the air flowo
In order to obtain characteristics which more accurately
represent sections workin_ in a propeller, the values of CL
and L/D h%ve bo,,,._-eo:_r_cd f_rom propeller test data (Reference
.u7Z) The p opejTors tes%:,£ _'_:'_'_standard N,:',.vysections,
C L and "m,/D cur":,rcsL-_''_0_7c.<_l_i9/tcd _{o_ a f_w s,sotions of medium
camber. These curves re:. the section im,vin_ a camber of .IS
are shovm in 9"iS . 8 '_:-,_ curves obfit_inc_ '_,l . the variable -__.en,:, it y
wind tu__e! tests at _00 atmosphare:_ for -the section havin_ a
camber of .i;? are also sho_,n in F _" •
_. S It wi.].! be noticeo, that
the lift curves are, ]parallel, but the an_le of attack for zero
lift is sJoout I degree icy:or for the curve calculated from the
N.A.C.A- Technicaf_ Uote No. 244 5
propc!icr tests.
It scorns reasonable to assume that the variation of lift an<]
dra_ with section thickness is the same for wing sections and
propeller sections. Therefore, for propeller work, a set cf
characteristics for these sections covering the full ran_c of
thiclmess mi@ht be based on the curves calculated from the mro-
pe!ler tests for a camber of ,In and the variation for other
cambers obtained frcn_ th_ airi_oi! section tests in the variable
density t_mnei. Fi:<, S shows a set of such curves which _mve
been faired and cross faired. The .7,ift coefficient at 20 atmos-
pheres for e,qochsection toots! has been obtained in relation to
that for the section of camber .12 at emch an_<!e of attack.
The faired curves for _'-" relation '_In±s _ p!otted
CL i or camber .
a_ainst camber are shorn in Fig. 4. The values of the lift
coefficients for all cambers excepting .12 shown in Fig. 3 l_zve
been obtained throuch Fi_. 4. The values of L/D in Fic. 3
have been obtained in like manner.
This provides a set of propeller section characteristics
to be used with any accurate form of the blade element theory
which takes into account the inflow and the blade interference
(Reference A)_ For all excepting the thickest sections they
may be used for any Reynolds Number, but compressibility of the
air at speeds approachir.g that of sound is not taken into ac-
eount •
i_.A.C._- Technical }Yct_ _o, S44 @
Comparison of Navy Propeller Sections with Other Airfoil Sections
Tested at _!i Scale meynoles _umber
In Fl<_. 6 the maximum L/D found in the variable density
tunnel at 20 atmospheres for each of the Navy propeller sections
is plotted a_<_inst section camber. It will be noticed that ex-
cept for the thilmest section they all plot close to a strai[_ht
line. It was n_ccssar7 to use a different method of supporting
the section having a camber of .0% in the test due to its ex-
treme thinness, so the high L/D found for it is probab!y due
to an error in the drag reading. It is possible, ho_vevcr, tb_t
the sections show rapid improvement as the camber is reducc<i
from .08 to .06.
The maximum, values of L/D of some other sections which
have been tested under tbe same conditions in the variable den-
sity o n_e_ are aT so p=o_t & Fi_ 6. Each of the values is
hisher than that of the propeller section having the same camber,
indicating that for full scale Reynolds Number, better propeller
sections could be designed for all cambers with the possible ex-
ception of the extremely low ones. More complete investigation
has shorn that this holds true _ov__ the entire working ....o-r_.... _e Of
the sections and. not _ ..... _'".___ for the Loint of maximum. L/D The
use of propeller sections similar to the Clark Y or the U.S.A.
S5-B should result in an increase in propeller effieienolr of
from 2 to 5 per cent over Navy propeller sections, if this is
,_, ,C.i_ • Techric_,l l_ote To. 244 7
_ _ fa.:__ :¢ ofco_!fi_,_o& i:u ._roDoiler tcst._, full scml_ tests on a '-_'_
i:,:oz'ove& propclier sectiors would be a ', _.,e_.p to propGller de-
s i ttor3._
Cot_cl_ms ior.s
I. Sco,!e el-feet with che n_e of Rc)mol_.s !h.,_mber is negli-
...( . Jo
_ib!e for &fit excno_::,_ng vex_, thLck :,._avv _rop_,_er st,st _ .....
_Ji L.
_iven to be ueed :::t ce::::.e,;tzon with th,3 b±a&e elc':ucnt theory.
._ _,j2 e s:"5:r.s to be ,_, T,oss:'.]__ it-" of <- -.... si_i_ propel-
ler efmi_nc:._,__'-,'_, '-_" "_rc..."_ g -_,o S _er c¢::,_ by tl_e use of bet+er,,
SOOt " "'_"'
References
I ga'" :':' E,:_oz=,,_nN. '
_e D __ O. P.
• Wcick, Fred E.
4. Ueick, Frc,d E.
Chd_ra_-- -"- of Propel!•<a,Ty 8r
g,:-'_-_ :"_s '.[ :,c- _'d i,_ th9 Variable
L _:,._ i t;y "L': ; 'h .... _"
(To b_. ,ruLl__s_ed __.ater.)
The E._ec_,s Tin See_d ou Airsc ew
Pe:_-fomuanc;e. Eri-_ A ,,v Com. for
Aeron..P2:L{ _Uo. 83.- - 1924.
Prone.±¢r Demi2.m-":i' Extension of
.p,:_!!c:'s by ?':c:_u,-_ o.f the !,_odified
I:L "-':-_ ._.L<uE, n,: T; ...... . A.... n- . }T.A.C.
'f,;rL:,_"._:_,! Z'_ote _7o. _:o -1926. Fig. 5-6.
Prc,_eLler D<,.si[4n--I: Prrtctical Aopli-
_" ..... '_'_,:,_ ._7_.emcnt Theory.
....... .. _:-_;tac.L.::;_]. l:otc No. 235-
_LL,,'_ .: •
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...........
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"_.A.C.A. Technical Note No.2_4 Fig.2
Fig.B
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2° 3° 4° 50
A_g!e of e,t-!,ack
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Characteristics of propeller section of camber .12
_o I0 o
N.A.C.A. Technical Note No.S4-4
1.2
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_hs,_ra_teri_tics of l_,vy 1:
_ecti_)ns f_)r us_ witi_ b!a{
_heor r.
i I
a_, 50 4o 5o 6o 7
Angle of attack
I
c)
N.A.C.A. Technical Note No.244
1.6
1.4
1.O
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Fig.4
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.08 .12 .16 .20
Fig ._4
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0 ._
t
.t
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ZO °
-! ...........
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..... j
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cambe r C
Curves of the ratio _-_L b• er .12
-ii-
N.A.C.A. Teohnlcal Note No.24A Figs.5 &
yMaximum camber-I .0
....! ....1 ..1
.G25i I _ t'lO ', I I I
.... .05 _ .20 .30 .40 .50 .60 .70 .80 .90 _00
6
IFractionlL.E.l _ ,- 'I_,_,_.i.o_I.ooI._oI._o!._oo1
to_ o_o_._,.....____ ..... ___ .....
._o_.oo1.oo/._q._ot _,1
.................................. L _t ....;_-,._5 .sT t.'_4-1.56-b,.35.077
Fig.5 Navy propeller section curve. Ordinates in terms of
maximum oralnate.
28
26
24
22
_"2o
-I
•_ 18
_4
r_
14
12
Fig. 6
1, iI dR. _.F.-15
\ gN. _.C.A.M-4
0
\, _U.S.A.-5
_-C i a : k- Y
. \ \
, U. S _,.'-S!l
N _vy, p copel let sectio as_ "_--,,._
.04 ..08 .12
Section camber
35-A
°k .'-ot t.
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i
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°'-U. S.A.-387
I
.16
I
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Chart of maximum L against camber.


Navy propeller section characteristics as used in propeller design

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