Table Of ContentHOW TO BUILD A
‘CRETAN SAIV
WINDPUMP
HOW TO BUILD A
“CRETAN SAIL’ WIND-PUMP
for use in
low-speed wind conditions
R.D. Mann, Al. Agr.
Agricultural
Gambia Christian Council
Wast Africa
INTERMEDIATE TECHNOLOGY PUBLICATIONS
The printing of this publication hes been made possible by
‘generous grants from three donors who wish to remain
anonymous.
Published hy intarmadiata Techno‘ogy Publications Ltd,
1108 ) 105 Southampton Row, Londen WC1B 4HH, UK
@ Intermediate Technology Publications Ltd +979,
Reprintad 1983
Roprinted March 1988
Aeprinced February 1992
§SBN 0.902031 66 3
fad by Artony Rowe Ltd, Chippenham
CONTENTS
PART 1
Introductian
Meteorological Considerations
Hydrologicat Considerations
Wind-Purnp Design
Wind Frequency Tables
G.C.C. Wind Pump Output, Table 2
Field Testing
G.C.C. Wind-Pump Fest Results, raph 1
Conclusions
Acknowledgements
PART 2
Construction details
Turniaate Frame
Furniable Bearings
Wind-Wheel Drive Shaft
Cranksvaft Bearings
Tower Head
Tower Upper Sectior
Toner Middle Section
Tower Lower Section
Tail Unit
The Wind-Wheel
The Sails
Pump and Connecting Rod
Drewing Sheets A-X
3
Sléanvesag
List of plares Page
Underneath wiew of turntable frame showing bearing
boxes if
Avview of the turntable 6
Turntable in operation on wwer 7
Making a turntable bearing track 18
Making upger tower section frame 2
Fitting bearing track or head frarie 22
Back view ot turrtable showing, on the fer le*t, the ball
hhofes to which the legs of the tail unit are attached = 26
Assembly of wind wheel 26
Fittirg the wind wheel 27
The sails in operation 28
The erected wind pume in action 32
List of iMustrations and tables
Map of the area 7
Table 1 Wind frequercies for site at Yundum 7
Table 2 G.C.C. Wind-pump outout on four selected days 8
Table 3 Wind frequencies for site 2 at Georgetown 8
Table 4 Wind frequencies for site 3 at Basse 8
Graph showing test results of the wind-pump 10
PART 1
Invoduetion
At the end of 1974, the Gambia Christian Council
stared a smatlscale villagelyvel agricultural
programme The rains in the Gambia occur from
mid-July ta mid October, and during the nine
month dry seaton there can be no fiekd crapping
without irrigation. The urowgh: conditions trom
1968 te 19/7, when werage rainfall decreased
from 31.6 inches to 3.8 inches per year, caused a
sho'tage ir domestic tood surly, and anv mathod
ff preducing food or cash craps in the dry season.
is of coneidarabe value to tie rura cammurity
The G.C.C. agricultural pragramme has consisted
of introducing vegetable production on # plane
basis, involving the use of lweslock-proof fercing
‘and ‘the sinking of 4 diameter concretelined
wells at the rate of twa wells per acre. The wells
ange ie depth from 15 in 35°, and. all water
extraction is by bucket and rope, the water keing
carried by hand to the vegetable plats. Each village
project Is planned far an area of oie ty sw ucres
under vegetables eacr season, one acre being
sufficient for 25 farnlies.
At their current stage of development, this
labourinteasive method of irigaticn hy hand ig
‘not limiting factor7o the succass of thase projacts
a the availablity of water from October to
May, together with improved «ethods of crow
husbandry, are he most important inputs.
However, when one considers future develop:
ment possiblities, and in particular the present
eed for troeptanting in all Sahelian aad near:
Sahelian countries, 2 emochanical meane of water
ting could have far-reaching results in making
such schemes feasible, and this has teen the
background thinking which prompted the devetop-
sent of the Gambia Christian Council Wind Puno.
Metearologicat Considerations
With reference to the wind trequencies given tor
three stations in The Gambia in Tables 1. 3 and 4,
will be seen that thera is 10 wind for 27% to
38% of the time, wind sponds of over 12 miles per
hour occur for only 38 0 3% of the year. and the
balance of 61% to 64% of the time has wind
speeds up to 12 miles per hour,
‘So for any practical use to be msde o* wind
power, a windmill dasion is required which can
start and operate in law wind sanads varying from
5 20 10 miles per hour
Hydralogicel considerations
“The river Samaia is lidal for a distance nf 150 miles
for imara fram the coast, and theraora water far
irrigation can o7y be taker trom the upper
reaches of the river. Tre graund water lever varies
‘ror 18! to BU, the dewier wells being mainly in
the eastern end of he county.
‘Mast dry-season vegetable growing areas are low
Iving with water tables varying fram 18° ta 25%,
but their location would require = high windmill
tower of 60" to 60" in order te reach the available
wind, However, there are sore areas, suitable for
dry-scason cropeing, with a water table af narmare
than 20° depth at the end of the dry season, and
it was decided to build a windrit 10 operate a
simple biston lift-pump,
Wind: pump design
Tre design was basse on the infrematian giver: in
the ITDC. publication, Food from Windmills, and
from practical advice given by Mr Pevar Fraenkel,
ITDG Power Project Engineer, In Septernber t876.
The design of the ‘Cmo’ windrril, devefoped by
the American Presbyterian Mission in Ethiopia,
‘as studied in detail, The ‘Omo" windmill worked
‘mainly ina wind regime of speeds from & ta
16 cites por hour, and it had oroblems asrociated
with turntable rotation ard directional stability of
the windheet into the wiad. Since our winds are
‘much lighter than those of the Ethiopian situation,
it was decided 10 make the wind-whee! 16° in
diameter and with six ams to permit the use af
‘wo, three, fou or six salle at required.
With referance =o drawings A and & (iven in
Part 2) the drive shaft tumns in three bearinas,
wo of oil-impregnated hardwood, the rear bearing
being a self-aligning ball-bearing which also takes
the axial thrust, The adjustable crank permits
uno strokes of 87%", 7” and St" to be used,
The pump is the same as used on the “Smo"
windmills: it ig a 3” diameter piston operating in a
16 pc. cylinder, ond it is connected to the
crankshaft via a universal join. The wurntaale is
fitted with four seated roller-bearing unit, which
run on a i" wide, 12° diameter bearing wack,
GAMBIA
sence 1,000,000
2 2e 30 muRe
Table + Wind frequencias for sire 1 at Yunctum
WIND SPEED JOR OM AM J J AS GO ON 0 Average
Gaim 2 17 % 1 12 20 30 39 di a8 48 28 20%
TA2eitesperhour = «707171727 «BD BB HO bs BAK.
1224 miecperhour «Bo 12:«16 «WB OB 14 8 8 kk BH
Qver 44 milesperhour 9 8 O CO 9 0 0 OO 0 Oo oO
‘The tai-fin has bean Lull hig! in relation to its
‘igth to obtain maximum leverage in the wind-
stream, The tall unit is of articulated design, with
ontrol rapes operated below the whee! to Dut the
wheel into of ot af the wind. The pesition of the
tail-in can be adjusted on tha teit boom to obain
tostance actos: the turntable bearings and 50
provide the best response te changes In wind
directien.
The tower is thiee-cormered and made in three
sections for ease of transport and erection. The
‘ower feat have platas welded on ta the battom of
the legs, end are sunk inta the graund to @ depth
cof 4". When erecting the tower, a spirit tevl is held
‘across the bearleg track at the top, the patition of
the Tags being adjusted in turn until the track ie
precisely feval in all directions. and the holes are
than filled in with tightly packed soit, The haight
of the tower is 23° fram ground level 19 the
bearing track,
‘Tha ‘main’ sails are made of heavy-duty marine
canvas, and the ‘starter’ sails are lightweight
The inner and outer sail comers. ore
fitted with aubber loops (details of which are given
In the construction deta in Part 2}, and it takes
io Table 2 6.C.C. Wind pump output on four selected days
sae Sins Bs 25rane Biber 1259 gi
Bos2%e Nexo Geoninae ofmns Shears Smet 1090 3a
S470 Nvwe ceso Tota mins Se fom Gaines ast
pene canis Une AMES Jee emi erh
J ries thins vequencies or ste 2 Georgetown
| OE ee
Calm 35 34 35 32024 73 «27 33 Be 46 A aD 35%
Tadimiscerhow SGT RS oo oh oe aS ee
ae
| rates ne rence torst 74 ese
| sinosreco SUF # ¥ 2 fA SOND mew
aim ee
1-12 miles per hour - 8 66 73 72 BO 70 64 49 52 43 41 B%
taza mies hour Ec ee
about six minutes to either fit or remove the salls,
‘The wind-whee is provided with struts and
Perimater-wire tension adjusters sn that the
wheel can be mada quite taut, and thus eny
tendency of the wheel arms to flex during gusting
winds is avoided.
‘As will be Seen in the construction drawings in
Part 2, the various windmill components Gen all be
unbolted to allow for easy maintanance and
modifications. After completing the workshop
construetion, all the mild steel perts are coated
with a murine anti-corrosive palnt to give tong
tetm rust protection,
‘The construction of this prototype machine
was carried out on a part-time basis, 2s and when
Cother field duties parmittad, in tha Ministry of
Agriculture engineering workshop . at “Yundum
Experimental Station, The constructioe com-
‘menced in Merch 1977 and was completed by the
end of September 1977.
Flos vesting
To feciltate testing, the wind-pump was sited
adjacent to a 74’ deep concrete water reservoir
tank at Abuko, 2% miles from Yundum. The top
of the tank was at grourd level, and the coxal lee
could he kept constant, the sutor lifted being
regsured ie rurs aud ter drained back int the
revervcur
There were a tery scavtered trees of up 0 38 1"
height, hot nane with n IDM yams af te wind
pune, and at 100 yarsk and heyore tre Tee
Foe was mainly cll-naim. The tstraction
wine-I'2W Cask by his wegatation asco TsIDEFe
ce fae'y typieal e rhae whien would be tourd
gt other su tabe Purping sites. nital tied tnas
ins aut im Nevcenaar and Dever ber 1977.
‘eet “ittod 47 8% large sails,
wish he outer
The veel was
a size, ait cons
feorer G shown in cvawing Ui tele by rigs:
ober nope 1a the cutee sail oes cm the peti
meter wins, (with ths arranmene”i there 286 0
diesticnal scarility ie wind snes nf 8 m.p h. anc
ove Ihe ea pattern sss shariged to Uhige [sige
ils, core’s titted as wefere, end this provides
etter winghwhee! staoiliny and less sail-lapping
During the frst srials, the aris af Ure with
‘heel were nat fitted with support steuls TL was
fennnt that thie ww edootiael was tne flexihle
in gusting winds, and struts ware tur fread to
teach arey weigh sulved this mechanical proble'n
and made the wheo compleraly rigia.
The taif boom design was also vvsiged. The
initia tail boom was mace af 17x 1” annle iran,
BO" total tength buat this allowed baisting nf the
booms and causad the 1ailfin to shake under
wind pressure. A new tubular tail boom was
designed (as shown in drawing QI, and to counter-
Lalance the extra weight of the struts on the wheel
it was then possible tc fit the tailsin @ further
away from the turntable
The result of these alte-ations ta the Wheel anc
teil, wagether ith hve use OF thine Farge sil, wees
improved sensttraty to changes in wind direction,
but the'e as still some sail lapping and the whee!
would tend to overrun at wind speeds above
9 mupsh. Durieg sudden high-speed gusle, dhe back
fof the sails would occasionally hit the Lower legs,
and there was still the (euuerey [er the wheel 10
move 19 the right-hand side around the tower as
the speed of the wind and the wheel incrensed,
‘The large sails provided avecuste saif area to
drive the wheal, but curing ligtt winds the starting
performance was. pacr. Ta provide more etarting
lorque, three sirallsi7e sails mare Uesigned with
4 na- oad ‘angle of attack’ to the vind cf approxi
mately 19°
During uniform wind conditions, in February
and March 1978, the sail arrangements of 3
‘rain’ ssik, 2 ‘Trait’ sails ane 2 ‘starter’ eile, and
‘main’ sails wth 3 ‘Harter’ sails were compared,
are ie war fae Oral for @ wind speed ranye of
§ te 10 mph. te test nwerall pertarmance was
tained with 3 ain’ sails and 2 starter’ sails,
ter frther teal, found that sail
flanpirg and any tondensy of the erain sail to hie
che tower "ags, could La: Cuirslelely eliminated by
ryire te Wad ug edges of te sas tightly against
the ware! a-ms, znd 4". sher considerable imarove=
net in whee! “oteon and ouIMa.ng OUSE.t was
ceslained fy “ting leregsha. nF rabhee From
Prucishing whee arins i the oucer sail curser,
full deta ls ef wach are givun int Curt 2 under
ie Sevvun aeated “Sal. This peavsion ol af
easceeated cormect an oft each sail Vailing edge
a0 730 the effec: cf gaverning the wheel specu
uring Tigh gusts, an Uns prevent
it war
he wheal
The final improwement inva val wuurteravting
she Tencency oF the wheel co swing to dhe right
hhand side around the teiaer a8 the wheel-rotation
snwed increagea. “0 do this, thy hoor ext Ie2e
Urawing P) was releasoa, and in the first instance
the la beo-n wise ted 11a positian 10" to the lett
Houking forvaas lo the wreel). The wenency was
ow for the vaizel to rrave progressively around
tha lower “0 the leftchand sice: a final nositien of
about 74” lo the left »as than fund te qive the
best diectinrs stability of the wlwel, and the
boom was fixod in this pasition for the remainder
of she trials,
For the pumping tosts, two ceums teach of
43.4 gallons capacity) with screwtype outless at
the hotiam were placed or the reservoir wall
The pump inlet was connestod viag 1!2" diameter
owe, pie to 2 1%” factory-matte brase toot
valve pieced in the wator :ank. The punip outlet
was taken by a 1%" ameter ov.c. pipe lo the
drums. ‘Nind-un wes measured by an integrating
cup anemameses mounted on a pole at a heignt
ot 8
‘ait we to Graph 1, tre windspred was
Calculated from the time taken to till a drum and
she wind run at shown by the nemometer at the
commencement anc cample:ian of each drum:
filling perind Qn some of the lest days, the total
Tift (measured from the water reservoit surface to
the purmp outlet, vertically) was 13''4", and on
others it was 14° 1”, so all output figures have
been suuated io footgallons for ease of com
parison, The work done in foot-gallons per hour
‘was calculated by noting the time required to fill
each drum. 45 ona drum was filled ta the top, tha
fen
WORK DONE: FOOT/GALLONS PER HOUR
13,000 GRAPH T
rac00 ’
‘TEST RESULTS OF THE
bc, WINDFUMP
11 090
12,080 @ ‘Gc! 1 PUMP
-oMo'— 1 PUVP
200 @ ‘omo"— 2 PUMPS
000
1080 :
’
6.000
,
,
4.000
seve
3,000
2.000
ave
z é 'o nm 26 18
c 6 ho eB
