Daniel Guggenheim Air•hip Institute
Akron, Ohio
Etf· ct of ?uaela~ Sp<>ilers
On Fuael&g Drag. Lift and Pitehing Mo:rnont
This report is a description of tests conducted on an a1rs1.ip hull
rnodel Gquipped with te.1.1 thtrfaces, to slmulato e.n irple.ne fi.ll li:...i;;e model,
around which we.x ridgee, representing inflated apoilers, were a.tta.ohed at
several locations along its axia. The teats, conduoted in th 6'- 6
di8..l!leter vertical wind t •.mnel of the Dan~el G'l.lr-genheim Airship Institute
at Akron, Ohio, were made to deterrrdne th etfeot of the spoilers upon the
draG• lift and pitching moment of the fuselage.
!~-~:__r1al and Test Set-Up
fhe model for these tests, furniahed by the Daniel Guggenheim Airship
lnsti tute, was a model of the Akron-.iaoon Airahip hull, five .feet long and
having a maximum diameter of ten inches. The dea1gn or the ·spo i ler outline
waa furnished by the .B.F.Goodrieh Company. Two type• wore us&d, hav ..
round a_~d trillnguls.r cross-sections. The tests reported here wero ms.de
with round spoil9rs and observational tests only were made with the triang~
lar ones. However the indications were that the a-ame type and order of
. results would be obt ined for theee spoiler:s as for the round ones. Fig•
ur"3 I gives a eketoh of the spoiler designs, the model and the placement
of spoilers on the mod 1. Com~inations of f'our posi tione alonG the axis
'-Y"ere te sted , these being the F, c. v. and T location!!, pla.oed at 27. 31i.
44fl, o'l.4~, and ea.s; ot the length. measured from the nose of t .~ model,
respectively. The epoilers were made of a caulking eompound and wax,
shaped to simulate epoilers when inflated.
l'he model was suspended in the tunnel by means of struts o.tt'..lohed
to t.he sides of the model at 1.t& center of gravity.. These struts, sur•
roL,nded by i aolated ahi ld..i.ng to eliminate tneir effeot upon the drag
m.eas..trements. were then fa tenod to the wind-tunnel-balanoe frame aa shown
in Piv..ire II.
The suspension method usef has ristinct advant~res in the simplicity
with hich the model ooal<l be rernoverl f.or ohange of spoilers o.nc the
method 'ti,f which the ngle of a ttaolc oo'11C h e changed. A disadvantage in
tf.e system a t nat the struts lnre directly upstream from the tail aurfaoe
s at low angle• of attaek,oauslnG slight interference.
Lioasurements of the drag, lii't anc pitching moments were me.de at
various angles of• attack, .from ~· to +15•. with a. wind veloeity of 100
mile per hour.
2
Dani•l Guggenhei Air-111p In..tltute
Akron. Ohio
T••t Hoeult•
The toroee and moment• were roduoed to ooettioient• in t.:rma ot both
volume ad ·area. aa defined belmrt
•
where
OD area • Drar/'cto · A
en • Drar/~ • v% vol
Otar.a • Litt/q0 • A
CI.vol • Litt/q0 • V~
C·iii-r .a. r. ea • Moment/q 0 • ..I · A
CM • Moment{q0 • V
vol
V • volume ot model
A • maximum orosa aeotion of model
,I • length of model "°= l/a f~
Th a eoef1'io1enta. plotted againat the angle ot attack to~ "farloua apo1ler
position•, are given in Figs. III-V.
It will be noted in Figure• III-a and III-b. that the drag ia 4ef1nit.ly
inorea.aed by the use ot spoilers, the amount of 1nore&ff depending upon.
the number and the location of the apo11ere. The etreot upon the drag at
0° angle or attack he.• been summarised in Table I, where the value• ot
CDarea and the drag area value• have been lilted. (drag area • A • ODar.a).
The drag are a tor the· variou• apo1lera have been compared to the no•
spoiler data and expressed 1n percent. Typical full-ffale drag area
· values are also liated tor a ship having 11 fu.elage aix time• the model
si e, i.e. 10 tt. long and a -.ximuii diameter ot 5 tt. Tot.al drag 1norea••·
oompared to the no-spoiler teeta, have be~n ocmputed on the ba•i• or th9
assumption that the tuaela&e drag repre•en't#a 36'/b of the total airplane
drag.
It will be noted that a e1ngle spoiler approximately doubled the
f uselage drag. the one farthest ahead producing the maximum etfeot. Two
spoilers located near the center of the hull trebled the t'u.aelage dr&g.
while three epoilera inor~ased this drag to nearly i"our t1-• the no•
spoiler values. With a third spo·iler pla.oed near the tail, the drag in ~
creased only about 34/b of the no -apoiler Yalue, aa •hoe b7 OQ.Uparing the
T + C + B and the C + B values. The total drap are inorea.ed about so;
W1 th OlllllJJ • a.Q.Q.at. 7 O'-fo with two and about laoj w1 th the u•e ot three 1poilera,
indic ting a very definite drag 1nor-ea1e due to the epoilera.
Comparison• of the lift and moment O\U"Ye•• •hown in Figa. IV .... , IV-b,
V -a and V -b •how that lift wa.a 11 ttle af'teoted b7 the uae 0£ apoilere and
the effect on the pitohing moment, while •lightly gnat•tt, oould be
Daniel Guggenheim Ail"ahip Innl tute
Akron, Ohio •
considered a• negligible. The greate•t departure trcm the no-.po1ler GUJ"'t"e,
for the moat etf'eoti.,.. epo1l•r combination w.• only o.oa 1n the wlue ot
Cy a. It will be not d that there •• aome •oatt.ring or point• bl the
liK8ind oment curvee at low angle• or attack du. to the 1nterteNDOe o~
the strut on the tail eurtaoea mentioned above. Bowe-..r thi• aoatt.rlng
11 ot little illlport, considering the total lilt and llS8nt or th• ooapl•te
plane.
It may thu• be ooneluded that apoil•r• ot the type aonaidered oould
be u•ed to inorease the drag or the airplane w1 th negligible etteota OD.
the et.ability or Mn.O•uverab111ty of an &J.rplaae.
P. o. Hues
10"31-41
Spoiler
Location
};one
F
c
1:3
li'+C+B
C+ l)+T
C+B
F+ :d
Daniel Guggenheim Air•hip Institute
Akron, Ohio
Table I
Efteet or Fuselage Spoiler on Drag at oo Angle o£ Attack
(Tests made on Akron•.Macon Airship Hull with Tail Surtacea)
cna.ree . a.t a: • 0
Model Drag- Are&
rt2 . · · -;6 .. Pull Soal 8nrag*-
Ar•·~~f1
0. 097 0.053 100 1.90
0.232 0.126 258 .(~66
0.213 0.116 219 4-.18
0.185 0.101 191 3.64
0.374 0.204 385 1.34
0.324 0.177 3$4 6.31
0.291 0.119 300 5.72
0.291 0.159 ~00 5.72
Distance of spoiler from nose ot model, in % ot :model length
FQ i1.z~. O• 4.f:%, B• e1.4j(. T• aa.s;g
·.rotal Drag••
' ~
100
1'8
142
l~Z
100
182
170
170
• Full scale ship assumed tG 6 times model sige
** Assumption that fuselage drag is 36" ot total drag.
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FUSELAGE
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.LOCATIONS OF SPO!C-ERS
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SPOILER
CIRCULAR SPOILER
tJ.
OETAI L A
J •
.,
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Daniel Guggenheim Airship Inst1 tu e
Akron, Ohio
FIGURE II. View of Airship Model with Spoiler Suspended
in Wind Tunnel
Daniel Guggenheim Airship Institute
Akron, Ohio
Daniel Guggel¥teim Airship Institute
Akron, Ohio
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Daniel Guggenheim Ai~ahip Institute
Akron, Ohro
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...,,, . Daniel Guggenheim Airship Institute
Akron, Ohio