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HOW 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