The Evel Knievel of ENG2000 FINAL REPORT York University, Department of Engineering ENG2000

Transcription

1 The Evel Knievel f ENG000 FINAL REPORT Yrk University, Department f Engineering ENG000 Team 5 Brandn Rbinsn bran@yrku.ca Piratheepan Jeyakumar pratheep@yrku.ca Lei Ta leita@yrku.ca Dwaraga Dushyanthan dwaraga@yrku.ca Prject Manager: Brandn Rbinsn Presented t Prfessr Eshrat Arjmandi On April 0 th, 007

2 Table f Cntents.0 Abstract....0 Intrductin Backgrund Infrmatin. 4.0 Design Issues.. 4. AutCAD Cncept Drawing 4. Materials Used 4.3 Hw it Wrks 4.4 Advantages. 4.5 Disadvantages. 4.6 Risks Final Budget Other Design Issues and Experiment analysis Spring-Cil Design. 6. Rubber Band Design 6.3 Gunpwder Design Bttle-Rcket Design Mathematical supprt. 8.0 WBS 9.0 Lgic diagram Gantt chart.0 Timetable...0 Analysis f Demnstratin 3.0 Lessns Learned and Cnclusins 4.0 Cntributin f team members. 5.0 References

3 .0 Abstract Over the curse f the semester, this team has been designing and building a rcket car fr the Evel Knievel prject. The gal f the prject is t design and build a land vehicle that travels up a ramp and becmes airbrne at the end f the ramp. The ramp is.83 meters lng and 40 centimeters wide with an incline f 5 degrees. At a distance f five meters away there will be a target that has an area f ne meter square. The gal f the car is t land n the target. The target is mved repeatedly and a vehicle can prceed t the next stage f the cmpetitin if it successfully lands n the target r a grup member stands behind the target and catches it until a winner is identified. The budget f the prject is $5. Over the curse f the semester, the design team has apprached many barriers and had t make many changes t the design. The team started by designing a bttle rcket car, then thught f a better idea. A butane-injected bttle rcket car was designed. Thrugh feedback, the design was scrapped due t difficulty in pressurizing the butane withut xygen present inside the bttle. Butane leads t safety issues. The bttle-rcket car successfully went ff the ramp but missed the target. Prvided in this reprt is a cmplete prject plan, design issues, final budget details, calculatins, backgrund infrmatin, and an analysis f the demnstratin..0 Intrductin The gal f the prject is t design and build a land vehicle that is prpelled by sme frce up a ramp, becme airbrne and land n a target five meters away. The ramp is.83 meters lng and 40 centimeters wide with an incline f 5 degrees. The target will have an area f ne meter square. The target will cntain a 30 centimeter diameter green zne where bnus marks will be awarded if the car vehicle lands n it. The target is mved repeatedly and a vehicle can prceed t the next stage f the cmpetitin if it successfully lands n the target r a grup member stands behind the target and catches it until a winner is identified. The team designed a car that has fur rubber wheels, an aerdynamic bdy and a mdified -L bttle that will hld abut 600 ml f water. The muth f the bttle has a valve attached, which is designed t fit a stpper with a valve stem. The valve stem is used t pump air int the bttle with a bike pump. The amunt f water and pressure was determined thrugh calculatins and trial and errr. The team s design perfrmed fairly well in cmparisn t sme f the ther cars in the cmpetitin. Its failure t win is mst likely due t time cnstraints. The design was changed frm a bttle-rcket t butane, but the butane idea had t be discarded due t safety cncerns a few weeks befre the cmpetitin. The team feels that if they had mre time fr testing, they wuld have been able t give a better analysis f the car, leaving less rm fr errr, and then hpefully hit the target. The team encuntered prblems later n in the prject, but enugh slack time was left t prepare a car that wrked fairly well. During the cmpletin, the car veered ff t the left and lst cntrl thrugh the air. A vide recrding was analyzed. It seems that it lst cntrl due t a center f mass issue. The car was nt crrectly balanced. It is difficult t balance the car because the weight is cnstantly changing since the vlume f water is depleted as it is prpelled. Thrugh mre testing, the directin f travel wuld have been made mre accurate and mre precise. 3

4 Prvided in this reprt is a cmplete prject plan, design issues, final budget details, calculatins, backgrund infrmatin, and an analysis f the demnstratin. 3.0 Backgrund Infrmatin The histry f rckets dates back t 00 AD, where the first rckets knwn as the "Chinese Fire Arrws" [] were made. It is said that nly after Newtn discvered the laws f mtin in 687, that the actual scientific principles behind rcket science was understd. Tsilkvsky's rcket equatin (903) uses the cnservatin f mmentum and applies it t the principle f the rckets. Hwever, it is fund frm a recently discvered pamphlet by William Mre, a British mathematician, that this kind f derivatin was used lng befre 903 by the ryal military academy in England fr weapns research [4]. The first liquid-fueled rcket was launched in 96 by Rbert H.Gddard [3]. Water r bttle rckets are simple t cnstruct and have n engine, thus, the flight is similar t a bullet being fired frm a gun. This type f flight culd be termed as ballistic flight []. In a ballistic flight, we assume that the nly frce that acts n the rcket is its weight. But in the case f the bttle rcket, there are ther frces like the aerdynamic lift and drag that acts n it. S this kind f mtin r flight is nt strictly ballistic. Numerus advances in the field f rcketry have been made and tday, mdern rcket science invlves the explratin f space by the use f rckets/vehicles that carry peple t uter space. 4.0 Design Issues This sectin will utline the final design f the rcket-car. Included in this sectin is an AutCAD cncept drawing, the materials used, hw the design wrks, the advantages and disadvantages f the design, and the risks. 4

5 4. AutCAD Cncept Drawing The rcket-car is prpelled by a bttle rcket. Belw is a cncept drawing dne using AutCAD. FRONT TOP SIDE 5

6 4. Materials used: - -L Bttle - Water alve - Fam - Rubber Wheels (4) - Metal Axles () - Blts () - alve stem - Tefln tape, Clear tape, Weldbnd glue, Cement glue 4.3 Hw it Wrks Prpulsin System: The car must be able t bridge a gap f five meters. T d this, we thught f a way t attach a bttle rcket t a car. The car is prpelled by pressurizing a -L bttle f water attached t a fam bdy. The bttle is attached by using clear tape t wrap arund the fam bdy. This is the mst effective way t attach the bttle t the bdy because it is cst-efficient and light. The bdy must be aerdynamic in rder t mve effectively. The bdy f the car is made f fam. Fam was chsen because it is light-weight, cheap, and easy t cnstruct things with. The frnt end is shaped like a split-dwn-the-center triangular prism with the pint being n the frnt end. This creates an aerdynamic car since it reduces drag. The wind will cut arund the triangular shape and pass by the car rather than push against it. The vlume r the size f the bttle determines the amunt f energy and pressure that the bttle rcket can hld. A L bttle is used in rder t stre the required amunt f energy and pressure needed fr the launch. Release Mechanism: At the muth f the bttle is a metal valve. A valve-stem stpper was design t effectively pressurize the bttle withut any air r water escaping. A valve-stem was remved frm a bike tire tube, and then attached t rubber washers. The valve-stem stpper is then placed at the pening f the valve. T pump air int the bttle t pressurize it, the valve was pened, the stpper put int the muth f the valve, air pumped thrugh the stpper, the valve clsed, then the stpper is remved. During the demnstratin, n pressure escaped prir t the actual launch. T attach the valve, we wrapped rubber arund the utside f the end f the valve t fit the bttle. We wanted the fit t be as tight as pssible s it was difficult t push the rubber end f the valve int the bttle. The valve was then put inside f a freezer and frzen s it wuld cntract. The muth f the bttle was put in biling ht water s it wuld expand. After a few minutes, the valve was taken ut and cvered in Weldbnd glue and then put inside the muth f the bttle. After the glue dried, mre glue was applied, then Tefln sealing tape, then clear tape. During the first few tests f the car, the bttle experienced leeks and we culd nt get maximum pressure inside f the bttle. The valve was taken ff and the same prcess as abve ccurred. Mre layers were applied t ensure that there are n leaks. T launch the car, the valve must be pened. Greece was added arund the valve handle t make it pen easier because it was nt pening as easily as the team wanted. 6

7 The Base: Attached t the bttm f the base is fur wden blcks in each crner. There are hles drilled int each ne s that a metal axle can be put thrugh them. Rubber wheels frm a ty car were attached t the ends f the rd using blts and glue. Since the frnt and back wheels were n their same respective axle, the car is mre likely t travel straighter. 4.4 Advantages - Pwerful - Easy design cncept t implement - Cst efficient - Easy t cnstruct - Easy and fast t setup - Effective release system - Safe - Oxygen is easy t cmpress - ery versatile - Mre r less pressure and water can be used t change the distance it launches 4.5 Disadvantages - Can g ut f cntrl easily - Difficult t balance the weight - Weight cnstantly changes until acceleratin reaches zer - A spray f water ccurs frm the valve as it is launched 4.6 Risks The bttle rcket design is safe and des nt pse any envirnmental hazards. If the launch area is clear and there are n peple in frnt f the rcket when it is launched, n ne will be hurt. 5.0 Final Budget Item Cst -L Bttle $.48 Water alve $6.04 Fam $3.58 Rubber wheels (4) $7.9 Metal axles () $.8 Blts () $.38 alve stem $.7 Tefln tape $0.79 Clear tape $0 Weldbnd glue $0 Cement glue $0 Sum $4.45 The budget f the prject is $5.00. Accrding t the chart, there is an extra $0.55 that remains unspent. The budget was calculated carefully in rder nt t g ver budget. The items that cst $0 were bjects that the team already had and did nt need t buy. The items used during the testing f different designs were als already wned by the team members. 7

8 6.0 Other Design Issues and Experiment Analysis Many prblems n chsing the final design were encuntered. It was trublesme deciding the mst effective way t prpel the car up a ramp and travel 5 meters thrugh the air. A cntinuus frce is the mst effective way and there were many ideas that came up during the brainstrming perid. The ideas that came up were using a bttle rcket, strng springs, rubber bands, CO, butane, and gun pwder. The spring, rubber band, and gun pwder ideas were tested. 6. Spring-cil Design A spring can be cntracted t stre energy. This energy can be used t push the vehicle frward. The spring-cil was attached t a thin rd. It was then ciled as tight as pssible and the end was fastened tightly t a statinary bject. Tw wheels were attached t bth ends f the thin rd while the rd was held in place. When the rd was released, the spring unciled and made the wheels spin. A prblem was immediately nticed. The spring unciled at a very fast rate and mst f the frce was exerted n the bdy f the vehicle rather than the wheel axel. Cntrlling the rate at which the spring uncils wuld be very cmplicated. Fr this reasn this idea f a spring-cil was dismissed. 6. Rubber band Design The rubber-band design is similar t the spring-cil design. Since the rubber band is elastic we assumed that it will have a lwer rate f releasing energy. We tied ne end f a lng rubber band t the wheel axel. The ther end was tied t a statinary pint f the bdy. The wheels were rlled backwards, causing the rubber band t cil arund the axel. When the elastic reached its maximum stretch, we placed the vehicle n the flr and released it. The vehicle mved frward with fairly high acceleratin, but sn came t a stp. The rubber did uncil and it als prvided the axel with trque t make the car mve frward as predicted. But when the rubber band was fully unciled, it started t cil back arund the axel again in the ppsite directin. This ccurred due t the fact that the wheel was still spinning and it was cnnected t the rubber band. This created a trque in the ppsite directin and slwed the vehicle t a cmplete stp. This idea was als dismissed. 6.3 Gunpwder Design By lking at firewrks we can see the amunt f frce cmpressed gunpwder can prduce. We tried t harness this int ur vehicle design. A small cpper tube was filled with gunpwder and sealed n ne end. When we lit the ther end, the gunpwder burst int flames, but there was barely any frward mvement in the tube. The pwder was nt being pushed ut, s the flame went inside the tube. T slve this prblem we must insert a spring inside the tube which pushes the gunpwder ut while it burns and prduces the required frce. This wuld require us t find the spring with the crrect diameter and cmpressin length. This wuld make the design very cmplicated, and therefre this idea was als dismissed. 6.4 Bttle-Rcket Design The bttle-rcket idea was researched n the internet befre testing. We used a -L bttle and pumped air int it. We released it and the bttle prpelled with a lt f frce. The directin was nt cnstant but with further testing, this seems like it culd be a very gd design. 8

9 7.0 Mathematical Supprt When the vehicle travels up the ramp and takes ff, it takes a prjectile mtin. In the calculatins air resistance and frictin are neglected. The amunt f speed the car must have when it leaves the ramp is calculated belw. We als assume that the hrizntal distance it travels is five meters, and the length f the slpe is.83m. Fr the car t travel mre than five meters it must have a greater speed than the amunt calculated belw. y.83 m x y 5 y sin5 =.83m y =.83sin5 y = m tan5 x = = y tan5 x y x x x y = 5m = x t yt = tan5 5 tan5 = t y = y + at 5 tan = t 9.8 t = ( tan 5 ) t = t 9.8 t = t y x = = 5tan5 =.09m / s = 8.907m / s tan5 y + = x = 8.509m / s = 30.63km / h = Calculatins shw that the car must have a speed f 8.509m/s r abut 30 km/h t successfully make the five meter target. This implies that the final velcity f the car befre it leaves the ramp must be mre than 8.509m/s s that it vercmes air-resistance and the frictin between the wheels and the ramp. 9

10 The amunt f frce required by the prpulsin system must be calculated. Fr this we set the ttal distance f travel equal t the length f the ramp, the initial velcity t equal zer and final velcity t equal 8.509m/s. N F app Ө, 5 mg mgcsө mgsinө = 0m / s = 8.509m / s = + xa ( ) = a a = = 9.78m / s 3.66 = ma mg sinθ = m a = m F = F app ( g sinθ ) [ ( sin5 )] = 7.44m F mg sinθ 0

11 8.0 Bttle-Rcket Car WBS Bttle-Rcket Car Design Rcket Buy Materials Build Frame Build Bumper Build Nzzle Put bumper n frame Build alve-stem Stpper Attach wheels and suspensin Attach nzzle t bttle Munt bttle Fill bttle with water Cmpleted Bttle- Rcket Car

12 9.0 Bttle-Rcket Car Lgic Chart Bttle Rcket Car Mar 5 (0) Mar 5 Mar 5 Design Rcket Mar 5 Mar 5 (5) Mar 5 Mar 5 Buy Materials Mar 0 Mar 6 Mar 7 Mar 6 Mar 9 Mar 6 Mar 7 () Build Bumper () Build Frame Mar Mar 3 Mar Mar 5 Mar Mar 3 3 () Build Nzzle Mar 0 Mar () Put bumper n frame Mar 6 Mar 8 Mar Mar 3 () Attach wheels and suspensin Mar 8 () Mar 9 Build valve-stem Mar 4 stpper Mar 6 Mar 9 Mar 3 Mar 4 () Mar 5 Apr Munt Bttle Apr 3 Mar 6 (6) Inject bttle with Mar 7 Apr 4 water Apr 5 Mar 8 Apr 5 Cmpleted Bttle- Rcket Car

13 0.0 Gantt Chart 3

14 .0 Prject Time Table Date What Happened Jan 5, 007 Meeting Discussed design ideas Jan 3, 007 Meeting Discussed mre design ideas Jan 9, 007 Meeting Discussed testing design ideas Jan 3, 007 Meeting Discussed the testing f the design ideas, decided n bttle-rcket, discussed prpsal. Split up wrk between members. Brandn cver letter, putting tgether end prduct f prject charter Piratheepan wrk divisin sectin Lei preliminary milestnes and schedule design Dwaraga Intrductin t cncept f design Jan 9, 007 Cmpilatin f prject charter and handed it in Feb 6, 007 Meeting Discussed evaluatin prpsal. Made bttle-rcket design better by making it mre aerdynamic Feb 3, 007 Meeting Decided a gaseus fuel wuld be better t use. Each member will cnduct research Feb 0, 007 Meeting Discussed research n gaseus fuel. Decided t use butane as the gaseus fuel Drew a preliminary design Estimated a cst Feb 5, 007 Brandn and Piratheepan buy materials frm Hme Dept Feb 7, 007 Meeting Ideas were discussed n hw t start cnstructin Interim reprt details read ver and discussed A WBS was drawn up t aid the cnstructin f the rcket car Mar 3, 007 Interim reprt cmpiled Mar 7, 007 Interim reprt handed in Mar 5, 007 Meeting Discussed results f interim reprt Decided it wuld be better t revert back t bttle-rcket idea Brandn and Piratheepan buy supplies Mar 4, 007 Meeting Bumper, frame, and nzzle is built Mar 5, 007 Lei, Dwaraga, and Brandn prepare Pwer Pint slides fr the presentatin Piratheepan prepares the handut fr the presentatin Mar 8, 007 Meeting Bumper added t frame alve-stem stpper is built Mar 9, 007 Brandn gives the presentatin Mar 30, 007 Meeting 4

15 Apr, 007 Apr 4, 007 Apr 6, 007 Apr Apr 0, 007 Attached wheels and suspensin Munted Bttle Meeting Attempted t pump 45 psi int bttle but due t a leak, valve had t be reattached Meeting Tested bttle-rcket car n flat grund. Travelled 7 m n average Meeting Tested bttle-rcket n small ramp. Smetimes it landed 5 m away, smetimes it spun ut f cntrl Meeting Tested bttle-rcket n small ramp. Put extra weight in the frnt t try t stp it frm ging ut f cntrl Demnstratin.0 Analysis f Demnstratin This sectin is devted t what happened during the demnstratin and why. The pictures were taken frm a vide taken by Adrian asilescu. Figure.: The car prpelling up the ramp a mment after being released. Due t the car being pushed slightly t the right while the valve was being pened, it is ff center by abut 0 degrees Figure. shws that the car is nt pinted in the crrect directin when it is released. This is because it is difficult t aim the car withut any accurate measurements, but it is als due t a weakness f the bttle-rcket design. Frm figure., it is estimated that the car is pinted abut 0 degrees ff center f the ramp. Using simple trignmetry, tan(0 ) = x / 5 x = 5tan(0 ) x = 0.88 m Based n the estimatin, this means that if the car did travel the five meters, it wuld have been 0.88 meters t left, respective t the picture. The valve handle had t be pushed twards the right t pen it, which is what pushed the car in that directin. This culd have been reslved by applying mre grease t the valve, r by turning the car 0 degrees t the left befre launching. After the car left the ramp, anther prblem ccurred. In figure., it can be seen that the car starts t change directin at the mment it leaves the incline. This is because we cannt cntrl the density f the water inside the bttle. The water in the bttle is 5

16 Figure.: The car a mment after leaving the ramp. The car is being prpelled twards the left and is abut t spin uncntrllably. nt unifrmly distributed because it is a liquid and nly takes up abut 30% f the vlume f the bttle. Therefre there must be sme parts f the bttle that are heavier than the rest f the bttle. The nn-unifrm density f the water makes it hard t cntrl what directin the car will take nce it leaves the ramp. The water mves arund inside the bttle as the car mves cnstantly changing the center f mass f the car causing it t spin. Frm figure., it can already be seen that the car is nt ging t hit the target because the car is nt ging straight. It will mst likely keep turning at this pint. The car must be travelling straight at the target with the valve cnstantly acting as the center f mass. When the car left the ramp it was suppse t pint straight at the target, but frm figure.3, we can see that the car is pinting dwnward instead f upward. One majr reasn fr this imprper directin t happen is that at the mment the car left the ramp, the frnt was pushed dwnward. The car shuld be prpelled t cntinue ging straight but since the frnt was pinting dwn, the water in the bttle als went t the prtin f the bttle pinting dwn, when it shuld have been at the back where the nzzle is. As the frnt gt heavier, mre water went t the frnt. Since the frnt has nw been weighed dwn, the nzzle is nw pushing in the wrng directin. The bttle is n lnger being prpelled frward twards the target, but spinning uncntrllably. The biggest prblem abut the design is that the car flipped in the air after it went ff the ramp. The main reasn fr the car t land far away frm the target is that the car flipped in the air. The car flipped because the frce was nt cntinuus. As the car was mving, the density f the water in the bttle was changing with respect t time. Therefre, the frce that was being applied t the car was changing with respect t time. The water is always released frm Figure.3: The car spinning uncntrllably. It is spinning due t it being ff center was it launched, and the valve nt being the center f mass during the entire flight. 6

17 the same spt s this caused the travel path t be circular instead f parablic. As the car left the ramp, the frce pushed the car in a circular path. The last part t analyze is the energy. Althugh the car did nt travel the required path, it did have enugh energy t travel the five meters t the target. The car was prpelled int the grund causing the frnt end t break, as seen in figure.4. The bttle rcket generated enugh energy t make it t the target. If the valve was a cntinuus center f mass, the car wuld have travelled a range f five meters and hit the target instead f being frced int the grund causing it t break. 3.0 Lessns Learned and Cnclusins There are a few cncepts that the team culd definitely imprve n if asked t design anther bttlercket car. Mre testing n a ramp needed t be dne. The car did travel five meters n a different ramp, but it did nt happen every time. Mre testing culd have reslved mre issues. There are sme main issues that culd have been imprved. The center f mass f the car must be the valve where the water is sht ut until the bttle is empty. Fr a mass that is cnstantly changing by such a large factr, making the valve the center f gravity is very difficult. With mre testing devted t the weight f the rcket car, this may have been accmplished. The team used bags f sand in the frnt end t way dwn the frnt. Hwever, as the water ran ut, the frnt became heavier and caused the bttle t spin. Mre weight needed t be added t the middle fr when the water cntent is in-between empty and full. Figure.4: The car as it is landing. The bttle-rcket spun the car causing the back end t g straight int the grund. If the rcket travelled straighter withut ging ut f cntrl, it wuld have made it t the target. The car culd als have been made mre aerdynamic. Wings were ging t be used t create lift, but wings were restricted. The frnt end f the car was shaped t cut thrugh the air but there was t much frce pushing dwnward. The frnt end f the car shuld have been shaped like a cne t evenly distribute the frce. During the testing, there was a lt f unexpected behavir. This is due t the bttle-rcket s cnstantly changing mass. As the mass changes, it causes the directin t change, and as this happens, then the water mves arund and causes the car t spin uncntrllably. It was difficult t stay n budget. There were many types f valves that we culd have tested but valves are expensive. There were different designs we culd have used s we had t pick a cheap material t make the bdy ut f and it had t be easy t craft as well. 7

18 The dwnfall was nt in ur design, but hw we came abut ur design. If we did nt spend s much time designing the butane car nly t have t change ur idea due t safety cncerns, then there wuld have been a lt mre time t test the car. Testing was still dne, hwever, there was nt enugh testing t eliminate all f the tumbling. The car still perfrmed, but it culd have wrked a lt better. 4.0 Cntributins f Team Members The wrk-lad was distributed as evenly as pssible. The meetings were planned arund everyne s schedule s that everyne culd be present at every meeting. Prject Charter - Brandn did the cver letter and cmpiled the end result - Piratheepan did the wrk divisin sectin - Lei did the preliminary milestnes and schedule design - Dwaraga did the intrductin t cncept f design Interim Reprt - Brandn did the abstract, intrductin, lgic chart, cnclusins and cmpilatin f the reprt - Piratheepan did the mathematical supprt and design drawings - Lei did the prblem analysis, and the gantt chart - Dwaraga prepared the minute meeting charts and the WBS Presentatin - Brandn, Lei, and Dwaraga made the pwer pint slides - Piratheepan prepared the handut - Brandn did the presentatin Final Reprt - Brandn did the Abstract, Intrductin, Prject Timetable, WBS, Lgic Diagram, Gantt Chart, Cntributin f Team Members, and Design Issues - Piratheepan did the Mathematical Supprt, Final Budget Details, and Other Design Issues and Experiment Analysis. - Lei did the Analysis f Demnstratin, Lessns Learned and Cnclusins - Dwarage did the Backgrund Infrmatin, Design Issues, References, Cnstructin - All team members wrked tgether t cnstruct the car Signature f Team Members Brandn Rbinsn, Prject Manager Piratheepan Jeyakumar 8

19 Lei Ta Dwaraga Dushyanthan 5.0 References [] Flight Equatins with Drag. Natinal Aernautics and Space Administratin. Accessed n Mar 4, 007. < [] Mre, Jel. Using Newtn s Laws with Liter Bttle Rckets. 0 Mar, 999. Accessed n Mar 4, 007. < [3] Prpelling Equatins fr Rckets. Accessed n Mar 4, [4] Tsilkvsky Rcket Equatin. April 007. Accessed n Mar < 9