Control Line. Racing. Bill Lee IT SEEMS areas construction competition can best classified black magic seems flier has own way doing something undoubtedly best way Well want talk about little theory give some equations about fuel tanks shape placement act way flight hope will dis pel some myth surrounds topic First some basic facts weight water very near oz per fluid ounce converts 0346 pounds per cu since fluid ounce 1804 cu OK whos worried about weight water Certainly use very little flying model airplanes Well turns out fuel very near water weight 96 ounce per fluid ounce So want un derstand what goes fuel system can investigate using water know ballpark fuel Listed V-IF IF vj ii 1 -I1W 1 I1I ff11 1 FIGURE 1 WATER IN JAR PRESSURE IS FUNCTION OF DEPTH 0346 0346 IUIIIfIYiILILIiII below some densities various fluids Ounces Lbs Specific fi oz cu Gravity Water Methanol Ucon LB625 Nitromethane Fuel 50% nit ro 100346 810281 960332 1060368 960332 10 81 96 106 96 As can seen table alcohol lighter water nitro heavier oil slightly lighter com bine components make fuel result slightly lighter water about same density oil Now apply numbers few principles physics can help us swer question Any quantity fluid subjected force will exhibit some fixed characteristics important us pressure gradiant within fluid function much fluid piled above pressure can simply expressed formula P product G L D GThe acceleration affect measured Continued page 92 j7{F41 LI2ii -R4i2S j-- -v - 30NCFoHNv 2O1 UIiFA 11li ILl AIR 6 IL-FUEL IAIR TO ENGINE FIGURE 4 TANK CONFIGURATIONS MAIN TANK AIR Ei HOPPER -PARTIAL VACUUM FUEL TO ENGINE UNIFLOW CHICKEN HOPPER 36 Model Aviation NORMALLY VENTED TO ENGI now cost dollar fuel consistent its home brew good chance could have picked up some water air Theres also chance home brew consistent last batch horrible experience cost two en gines place two Nationals some backyard brew no oil Sure lots smaller fuel distribu tors have good consistent mixes fuel need careful will maintain two gallon cans same fuel side side can run differently seems unlikely muffler could cause inconsistent run except muffler pressure too much too little Experimenting size muffler pressure lines could help some instan ces muffler pressure fitting bad place receiving too much too little pres sure Finally back pressure muf fler may causing engine heat up and/or allowing engine breathe properly good run feel inconsistent runs stem fuel tank fuel lines tank must checked leaks broken tubing clogged lines fuel tubing must go straight line possible pick up tube spray bar No bends twists necessary have removable tank makes much easier adjust tank can moved up down relation spray bar engine can adjusted shims etc recall Bill Werwage inletted mounting beams 1977 Juno could raise engine air plane viewed upright position did get design doubt seriously 25% stunt fliers could plot airfoil mathemati cally accurately scratch doubt have aeronautical design training other what picked up model magazines like sit down sketch out new plane put working drawings using proven wing areas force moment arms tailplane sizes powerplant com ponents Actually canards have seen Nationals finals Open Stunt disguised combat planes have won Walker Cup trophy Ive seen person ever fly Sea Fury Yes know twin-engine stunter placed back 60s 1967 Rich Loomis first Senior best advice can give someone wants depart kit airplane look what works other accom plished fliers well competition over period years sit down draw up couple planes appeal using some full-size plans published planes have Nation als FAI competition adapt rough drawings utilize basic impor tant ingredients must present successful stunt plane wing area related engine size total weight aspect ratio wing force moment-arms both nose tail tailplane size tail vol ume flap size thrust line placement respect wing fuselage side area con trol movement equal unequal wing pan els leading edge sweepback dihedral airfoil size tip configuration Lastly stick design three four versions work out bugs information stunt PAMPA contact Wynn Paul 1640 Maywick Drive Lex Ky. 40504 CL Racing/Lee continued page 36 units acceleration due gravity LDistance measured inches free surface fluid point pressure being measured measured direction force causing acceleration DThe density fluid measured pounds per cubic inch What formula tells us pile up more fluid top pressure feel correspondingly higher model airplane three variables 6-loading due centrifugal force plane flies circle density fuel carried tank dis tance L distance free sur face fuel hole needle valve measured perpendicular line flight Fig illustrates pressure jar water meas uring pressure water various levels jar Note pressure ex hibited independent shape container three variables G L D couple intersting numbers can calculated formula First what kind pressure change would see variable L reduced some value some other value Fig 2 graph shows pressure change water under normal force gravity function depth water much water above point water pressure being meas ured As can seen pressure changes about 0346 psi/in water about psi 10 inches order verify number built simple test apparatus consisted 104 large diameter plastic tubing pressure gauge tachment enabled read pres sures various places column Much relief theoretical values supported reality measured 36 psi bottom column 104 ches water under 1-6 acceleration re sults 36 psi OK much water jar about fuel fuel tank First off have measure G force model hence tank fuel 6 loading can calculated know line length speed plane flying few representative values 6 listed below 6 1467 x MPH2 322 X line length few representative values G listed below MPHGs 525Gs 60 10012731114 10514041228 11015401349 11516841473 12018331604 12519891740 13021511882 13523202030 14024952183 14526762242 ISO28642506 160-flat Goodyear will pulling 1611 6s Slow Rat 160 flat pulling 1409 6s Now crank 6-values first equation along density fuel 0332 lbs/cu find pressure variation 1125-mph Goodyear over /2 psi per slightly less per Slow Rat tank oneinch wide pressure variation fuel level changes full empty will neighborhood pres sure variation will occur regardless whether using pressure fuel system course Slow Rat suction systems allowed psi variation will pressure system Goodyear too its pretty obvious wider tank will result greater variation general rule keep fuel tank narrow possible Tall long OK narrow possible keep pressure change minimum good question ask much does pressure change affect total pressure pressure system order find answer have know pressure created tank using crankcase pressure set up test stand measure found tank pressure untimed crank case tap about 14 psi about 16 psi ball-check used pressure line 92 Model Aviation $ WIN $ USE DAVIS DIESEL CONVERTER AT THE 1978 NATS Fastest Time CL$10000 Highest Time FF$10000 Highest Points /zA Stunt$10000 Davis Diesel Devlopment Inc Box 141 DEPT E MILFORD CT 06460 LiPHONE 203 877-1670 Six eight Db reduction 01 noise engines Proportional volumne expan sion chamber Large exhaust nozzle low back pressure Little no losa power No30109191049 So 30229401939 No 30043001949 xIIbI o 0 5 sod x sI No 304R1991911095 NO 005402940ttl95 NO 30641 45us 41309 NEW/ MUFF-L-IT SERIES Available B C engines REGULAR 1k REAR EX 1/2A MUFFLER Fits COX 049 engInes NO 30099491544 No 30940911549 order find pressure engine sees air have add pressure due centrifugal force can calculated above pressure placed tank pressure line Fig 3 illustrates pressure needle valve function distance needle valve free surface fuel basic assumption crankcase pressure results 14 psi Given /2 psi variation per pressure change fuel level changes signifi cant pressure fuel system three basic non-pressure tank set-ups general use today normally vented tank uni-flow tank chicken-hopper tank designs has different very predictable pressure characteristics modeler has either use allow design Fig 4 shows three types tanks gravity feed intended help visualize effect centrifugal force thinking effect gravity Note normally vented tank will cause pressure vary continuously level fuel tank changes full empty obviously reason kind tank causes rich-to-lean needle setting have encountered case uni-flow tank placement air bleed line im portant pressure seen en gine will equal pressure free surface fuel always level air bleed long actual free surface aboveo bleed air bleed above free surface fuel pressure will change continuously since tank has become normally vented tank bleed out fuel aspect uni-flow tank will cause problems need tank airtight after fuel has put air bleed can work properly tank sealed will act just like nor mally vented tank since precisely what has become chicken-hopper tank uses de mand feed principle tank really two tanks sealed large other normally vented tank small engine draws fuel small tank drawing fuel level down until vent large tank un covered allows bubble air get large tank corresponding quantity fuel flow back small hopper tank process repeats engine uses fuel out small tank chicken hopper has several notable characteristics First since hopper tank usually small pressure varia tion develops fuel used normally quite small desirable attribute Second tank set-up usually exhibits tendency run rich short until pres sure main tank decreases point vent hopper tank starts work Third main tank must airtight chicken hopper tank usu ally results large amount plumb ing install thing common three fuel tank set-ups re quire fuel drawn engine venturi action engine itself fact causes use pressure fuel feed systems events allowed events like Slow Rat Slow Combat pressure systems allowed its properly built installed fuel tank will make break entry Texas domi nant fuel tank set-up somewhat different Ive described above Look picture accompanies column read description knowledge design first used Larry Miller Larry Hoffman Corpus Christi Texas about two years ago general idea mount fuel tank inboard side nose plane causes have seen above significant amount pressure seen engine due centri fugal force tank placement fact plane pictures fuel free surface varies three ches two inches engine draws fuel tank translates pres sure 160 flat 14 psi tank full 94 psi absolutely empty Now tank just about half empty after 35 laps means pres sure engine sees about 12 14 July1978 93 F I9D9 qualities make moaei NATS winner same ones Sunday sport-scale fliers look Exceptional appearance start wth course FW 190s stark sinster shape has always excited modeiers important friendly flying qualities designs have always emphasized safety low speeds FW 190 has herited ability fly 80-90 mph right down near-hover landing wide-track gear makes ideal first tail-dragger Kit features Fuil-size plans showing rado retracting gear installat Color schemes decais THREE different FW l9CsSeparate 16-page instructon oooklet cutaway diagrams in-depth flying hints Diecut machined balsa nylon fttings formed wire cowl canopy etc Span 65 Area 730 Sq 4 6 channel Engine 60 GET ORGANIZED Mores set 4 Siurdy fries holds over 4 years favorite Byft mageorses 4 MAG FILES $495 Send $495 pbs $1 SO postage 50541mg DON INDUSTRIES PO BOX 388-K DOVER NH 03820 psi very nearly what pressure system would yield using untimed crank case pressure real key systems operation use carburetor has very large hole air arranged closed ground no pressure tank due centrifugal forcer open air take advantage tank pressure due centrifugal force have using old Pylon carb 1K/B once supplied old Series 71 rear-rotor 40 put big blob sol der throttle arm thatr does centrifugal force supply pres sure fuel causes carbure tor open take advantage pres sure carb has used weve found order get airplane air until centrifugal force builds up Weve also found must set needle valve air since no reliable way set needle ground have right air tank set-up looks rather wierd does work very well results ability use ven turi large used pressure sys tem corresponding increase en gine performance Bill Lee 2522 Tamarish Lane Missouri City TX 77459 Safe Flying No Accident CL Combat/Johnson continued page 37 Fast Combat Top Ten I Richard Lopez 2 Richard Brasher 3 Richard Stubblefield 4 Bob Burch 5 Chuck Rudner 6 Mike Guthomson 7 Neal Rose 8 George Cleveland 9 Phil Granderson 10 Paul Smith Slow Combat Top Ten I Paul Smith 2 Richard Subblelield 3 Mike Guthomson 4 George Cleveland 5 Andrew Lee 6 Paul Curtis 7 Gil Reedy 8 Chuck Rudner 9 Ed Brzys 10 Joseph Ambrose FAI Combat Top Ten I Neal Rose 2 Richard Imboff 3 Paul Smith 4 Max Mearns 5 Howard Rush 6 Richard Stubblefield 7 Gary Frost 8 Bob Burch 9 Phil Cartier 9 Chuck Rudner Last year received few queries certain well known very compe tent combat fliers list Probably common reason person MACA member question arises list MACA members count wins against other MACA members combat fliers general Others have complained though MACA members limited number contests can enter get points because weather no con tests California Florida Hawaii should have death grip Top Twenty case other factor Southern California fliers combat meets restricted-entry con tests counted toward standings would think objective throughout year would have fun contests best devis ing ways get points usually make pitch MACA end articles think Ill catch ofT guard time owe yourself become knowledgeable about Combat dont fly com petition join MACA send $600 $1000 overseas year member ship along name address MACA Treasurer Patty Sasnett 1443 McKinley Ave Escondido CA 92027 Please state renewal list MACA member responsible joining intention duplicate con test calendar found Model viation would like call attention sev eral contests deserve support first United States Control Line Model Airplane Championships held June 17 18 Winston-Salem North Carolina Bill Pardue has added FAI Combat year condition combat fliers step forward help run event Remember controlline AAAA contest 1978 big gest except Nationals MACA Combat Championships will held 8th 9th July Cincinnati Fast Slow FAI Combat will fea tured will Top Twenty chal lenge may challenge Top Twenty person $500 fee will go MACA treasury Speed Performance will featured both days will consist following Time takeoff 2 fly four level laps 3 3 inside loops 4 Pull out inverted fly four inverted laps 5 3 outside 1oops level flight stop timer 6 Seven level laps IS feet less top speed Score will total number seconds maneuvers plus num 94 Model Aviation CUSTOM TUNED ENGINES COMPETITION ACCESSORIES Cox 049A051 Specialists brochure send 13C stamp Kustom Krattsmanship Brochure Box 2699 Laguna Hjll5r CA 92653 714 830-5162
Edition: Model Aviation - 1978/07
Page Numbers: 36, 92, 93, 94
Control Line. Racing. Bill Lee IT SEEMS areas construction competition can best classified black magic seems flier has own way doing something undoubtedly best way Well want talk about little theory give some equations about fuel tanks shape placement act way flight hope will dis pel some myth surrounds topic First some basic facts weight water very near oz per fluid ounce converts 0346 pounds per cu since fluid ounce 1804 cu OK whos worried about weight water Certainly use very little flying model airplanes Well turns out fuel very near water weight 96 ounce per fluid ounce So want un derstand what goes fuel system can investigate using water know ballpark fuel Listed V-IF IF vj ii 1 -I1W 1 I1I ff11 1 FIGURE 1 WATER IN JAR PRESSURE IS FUNCTION OF DEPTH 0346 0346 IUIIIfIYiILILIiII below some densities various fluids Ounces Lbs Specific fi oz cu Gravity Water Methanol Ucon LB625 Nitromethane Fuel 50% nit ro 100346 810281 960332 1060368 960332 10 81 96 106 96 As can seen table alcohol lighter water nitro heavier oil slightly lighter com bine components make fuel result slightly lighter water about same density oil Now apply numbers few principles physics can help us swer question Any quantity fluid subjected force will exhibit some fixed characteristics important us pressure gradiant within fluid function much fluid piled above pressure can simply expressed formula P product G L D GThe acceleration affect measured Continued page 92 j7{F41 LI2ii -R4i2S j-- -v - 30NCFoHNv 2O1 UIiFA 11li ILl AIR 6 IL-FUEL IAIR TO ENGINE FIGURE 4 TANK CONFIGURATIONS MAIN TANK AIR Ei HOPPER -PARTIAL VACUUM FUEL TO ENGINE UNIFLOW CHICKEN HOPPER 36 Model Aviation NORMALLY VENTED TO ENGI now cost dollar fuel consistent its home brew good chance could have picked up some water air Theres also chance home brew consistent last batch horrible experience cost two en gines place two Nationals some backyard brew no oil Sure lots smaller fuel distribu tors have good consistent mixes fuel need careful will maintain two gallon cans same fuel side side can run differently seems unlikely muffler could cause inconsistent run except muffler pressure too much too little Experimenting size muffler pressure lines could help some instan ces muffler pressure fitting bad place receiving too much too little pres sure Finally back pressure muf fler may causing engine heat up and/or allowing engine breathe properly good run feel inconsistent runs stem fuel tank fuel lines tank must checked leaks broken tubing clogged lines fuel tubing must go straight line possible pick up tube spray bar No bends twists necessary have removable tank makes much easier adjust tank can moved up down relation spray bar engine can adjusted shims etc recall Bill Werwage inletted mounting beams 1977 Juno could raise engine air plane viewed upright position did get design doubt seriously 25% stunt fliers could plot airfoil mathemati cally accurately scratch doubt have aeronautical design training other what picked up model magazines like sit down sketch out new plane put working drawings using proven wing areas force moment arms tailplane sizes powerplant com ponents Actually canards have seen Nationals finals Open Stunt disguised combat planes have won Walker Cup trophy Ive seen person ever fly Sea Fury Yes know twin-engine stunter placed back 60s 1967 Rich Loomis first Senior best advice can give someone wants depart kit airplane look what works other accom plished fliers well competition over period years sit down draw up couple planes appeal using some full-size plans published planes have Nation als FAI competition adapt rough drawings utilize basic impor tant ingredients must present successful stunt plane wing area related engine size total weight aspect ratio wing force moment-arms both nose tail tailplane size tail vol ume flap size thrust line placement respect wing fuselage side area con trol movement equal unequal wing pan els leading edge sweepback dihedral airfoil size tip configuration Lastly stick design three four versions work out bugs information stunt PAMPA contact Wynn Paul 1640 Maywick Drive Lex Ky. 40504 CL Racing/Lee continued page 36 units acceleration due gravity LDistance measured inches free surface fluid point pressure being measured measured direction force causing acceleration DThe density fluid measured pounds per cubic inch What formula tells us pile up more fluid top pressure feel correspondingly higher model airplane three variables 6-loading due centrifugal force plane flies circle density fuel carried tank dis tance L distance free sur face fuel hole needle valve measured perpendicular line flight Fig illustrates pressure jar water meas uring pressure water various levels jar Note pressure ex hibited independent shape container three variables G L D couple intersting numbers can calculated formula First what kind pressure change would see variable L reduced some value some other value Fig 2 graph shows pressure change water under normal force gravity function depth water much water above point water pressure being meas ured As can seen pressure changes about 0346 psi/in water about psi 10 inches order verify number built simple test apparatus consisted 104 large diameter plastic tubing pressure gauge tachment enabled read pres sures various places column Much relief theoretical values supported reality measured 36 psi bottom column 104 ches water under 1-6 acceleration re sults 36 psi OK much water jar about fuel fuel tank First off have measure G force model hence tank fuel 6 loading can calculated know line length speed plane flying few representative values 6 listed below 6 1467 x MPH2 322 X line length few representative values G listed below MPHGs 525Gs 60 10012731114 10514041228 11015401349 11516841473 12018331604 12519891740 13021511882 13523202030 14024952183 14526762242 ISO28642506 160-flat Goodyear will pulling 1611 6s Slow Rat 160 flat pulling 1409 6s Now crank 6-values first equation along density fuel 0332 lbs/cu find pressure variation 1125-mph Goodyear over /2 psi per slightly less per Slow Rat tank oneinch wide pressure variation fuel level changes full empty will neighborhood pres sure variation will occur regardless whether using pressure fuel system course Slow Rat suction systems allowed psi variation will pressure system Goodyear too its pretty obvious wider tank will result greater variation general rule keep fuel tank narrow possible Tall long OK narrow possible keep pressure change minimum good question ask much does pressure change affect total pressure pressure system order find answer have know pressure created tank using crankcase pressure set up test stand measure found tank pressure untimed crank case tap about 14 psi about 16 psi ball-check used pressure line 92 Model Aviation $ WIN $ USE DAVIS DIESEL CONVERTER AT THE 1978 NATS Fastest Time CL$10000 Highest Time FF$10000 Highest Points /zA Stunt$10000 Davis Diesel Devlopment Inc Box 141 DEPT E MILFORD CT 06460 LiPHONE 203 877-1670 Six eight Db reduction 01 noise engines Proportional volumne expan sion chamber Large exhaust nozzle low back pressure Little no losa power No30109191049 So 30229401939 No 30043001949 xIIbI o 0 5 sod x sI No 304R1991911095 NO 005402940ttl95 NO 30641 45us 41309 NEW/ MUFF-L-IT SERIES Available B C engines REGULAR 1k REAR EX 1/2A MUFFLER Fits COX 049 engInes NO 30099491544 No 30940911549 order find pressure engine sees air have add pressure due centrifugal force can calculated above pressure placed tank pressure line Fig 3 illustrates pressure needle valve function distance needle valve free surface fuel basic assumption crankcase pressure results 14 psi Given /2 psi variation per pressure change fuel level changes signifi cant pressure fuel system three basic non-pressure tank set-ups general use today normally vented tank uni-flow tank chicken-hopper tank designs has different very predictable pressure characteristics modeler has either use allow design Fig 4 shows three types tanks gravity feed intended help visualize effect centrifugal force thinking effect gravity Note normally vented tank will cause pressure vary continuously level fuel tank changes full empty obviously reason kind tank causes rich-to-lean needle setting have encountered case uni-flow tank placement air bleed line im portant pressure seen en gine will equal pressure free surface fuel always level air bleed long actual free surface aboveo bleed air bleed above free surface fuel pressure will change continuously since tank has become normally vented tank bleed out fuel aspect uni-flow tank will cause problems need tank airtight after fuel has put air bleed can work properly tank sealed will act just like nor mally vented tank since precisely what has become chicken-hopper tank uses de mand feed principle tank really two tanks sealed large other normally vented tank small engine draws fuel small tank drawing fuel level down until vent large tank un covered allows bubble air get large tank corresponding quantity fuel flow back small hopper tank process repeats engine uses fuel out small tank chicken hopper has several notable characteristics First since hopper tank usually small pressure varia tion develops fuel used normally quite small desirable attribute Second tank set-up usually exhibits tendency run rich short until pres sure main tank decreases point vent hopper tank starts work Third main tank must airtight chicken hopper tank usu ally results large amount plumb ing install thing common three fuel tank set-ups re quire fuel drawn engine venturi action engine itself fact causes use pressure fuel feed systems events allowed events like Slow Rat Slow Combat pressure systems allowed its properly built installed fuel tank will make break entry Texas domi nant fuel tank set-up somewhat different Ive described above Look picture accompanies column read description knowledge design first used Larry Miller Larry Hoffman Corpus Christi Texas about two years ago general idea mount fuel tank inboard side nose plane causes have seen above significant amount pressure seen engine due centri fugal force tank placement fact plane pictures fuel free surface varies three ches two inches engine draws fuel tank translates pres sure 160 flat 14 psi tank full 94 psi absolutely empty Now tank just about half empty after 35 laps means pres sure engine sees about 12 14 July1978 93 F I9D9 qualities make moaei NATS winner same ones Sunday sport-scale fliers look Exceptional appearance start wth course FW 190s stark sinster shape has always excited modeiers important friendly flying qualities designs have always emphasized safety low speeds FW 190 has herited ability fly 80-90 mph right down near-hover landing wide-track gear makes ideal first tail-dragger Kit features Fuil-size plans showing rado retracting gear installat Color schemes decais THREE different FW l9CsSeparate 16-page instructon oooklet cutaway diagrams in-depth flying hints Diecut machined balsa nylon fttings formed wire cowl canopy etc Span 65 Area 730 Sq 4 6 channel Engine 60 GET ORGANIZED Mores set 4 Siurdy fries holds over 4 years favorite Byft mageorses 4 MAG FILES $495 Send $495 pbs $1 SO postage 50541mg DON INDUSTRIES PO BOX 388-K DOVER NH 03820 psi very nearly what pressure system would yield using untimed crank case pressure real key systems operation use carburetor has very large hole air arranged closed ground no pressure tank due centrifugal forcer open air take advantage tank pressure due centrifugal force have using old Pylon carb 1K/B once supplied old Series 71 rear-rotor 40 put big blob sol der throttle arm thatr does centrifugal force supply pres sure fuel causes carbure tor open take advantage pres sure carb has used weve found order get airplane air until centrifugal force builds up Weve also found must set needle valve air since no reliable way set needle ground have right air tank set-up looks rather wierd does work very well results ability use ven turi large used pressure sys tem corresponding increase en gine performance Bill Lee 2522 Tamarish Lane Missouri City TX 77459 Safe Flying No Accident CL Combat/Johnson continued page 37 Fast Combat Top Ten I Richard Lopez 2 Richard Brasher 3 Richard Stubblefield 4 Bob Burch 5 Chuck Rudner 6 Mike Guthomson 7 Neal Rose 8 George Cleveland 9 Phil Granderson 10 Paul Smith Slow Combat Top Ten I Paul Smith 2 Richard Subblelield 3 Mike Guthomson 4 George Cleveland 5 Andrew Lee 6 Paul Curtis 7 Gil Reedy 8 Chuck Rudner 9 Ed Brzys 10 Joseph Ambrose FAI Combat Top Ten I Neal Rose 2 Richard Imboff 3 Paul Smith 4 Max Mearns 5 Howard Rush 6 Richard Stubblefield 7 Gary Frost 8 Bob Burch 9 Phil Cartier 9 Chuck Rudner Last year received few queries certain well known very compe tent combat fliers list Probably common reason person MACA member question arises list MACA members count wins against other MACA members combat fliers general Others have complained though MACA members limited number contests can enter get points because weather no con tests California Florida Hawaii should have death grip Top Twenty case other factor Southern California fliers combat meets restricted-entry con tests counted toward standings would think objective throughout year would have fun contests best devis ing ways get points usually make pitch MACA end articles think Ill catch ofT guard time owe yourself become knowledgeable about Combat dont fly com petition join MACA send $600 $1000 overseas year member ship along name address MACA Treasurer Patty Sasnett 1443 McKinley Ave Escondido CA 92027 Please state renewal list MACA member responsible joining intention duplicate con test calendar found Model viation would like call attention sev eral contests deserve support first United States Control Line Model Airplane Championships held June 17 18 Winston-Salem North Carolina Bill Pardue has added FAI Combat year condition combat fliers step forward help run event Remember controlline AAAA contest 1978 big gest except Nationals MACA Combat Championships will held 8th 9th July Cincinnati Fast Slow FAI Combat will fea tured will Top Twenty chal lenge may challenge Top Twenty person $500 fee will go MACA treasury Speed Performance will featured both days will consist following Time takeoff 2 fly four level laps 3 3 inside loops 4 Pull out inverted fly four inverted laps 5 3 outside 1oops level flight stop timer 6 Seven level laps IS feet less top speed Score will total number seconds maneuvers plus num 94 Model Aviation CUSTOM TUNED ENGINES COMPETITION ACCESSORIES Cox 049A051 Specialists brochure send 13C stamp Kustom Krattsmanship Brochure Box 2699 Laguna Hjll5r CA 92653 714 830-5162
Edition: Model Aviation - 1978/07
Page Numbers: 36, 92, 93, 94
Control Line. Racing. Bill Lee IT SEEMS areas construction competition can best classified black magic seems flier has own way doing something undoubtedly best way Well want talk about little theory give some equations about fuel tanks shape placement act way flight hope will dis pel some myth surrounds topic First some basic facts weight water very near oz per fluid ounce converts 0346 pounds per cu since fluid ounce 1804 cu OK whos worried about weight water Certainly use very little flying model airplanes Well turns out fuel very near water weight 96 ounce per fluid ounce So want un derstand what goes fuel system can investigate using water know ballpark fuel Listed V-IF IF vj ii 1 -I1W 1 I1I ff11 1 FIGURE 1 WATER IN JAR PRESSURE IS FUNCTION OF DEPTH 0346 0346 IUIIIfIYiILILIiII below some densities various fluids Ounces Lbs Specific fi oz cu Gravity Water Methanol Ucon LB625 Nitromethane Fuel 50% nit ro 100346 810281 960332 1060368 960332 10 81 96 106 96 As can seen table alcohol lighter water nitro heavier oil slightly lighter com bine components make fuel result slightly lighter water about same density oil Now apply numbers few principles physics can help us swer question Any quantity fluid subjected force will exhibit some fixed characteristics important us pressure gradiant within fluid function much fluid piled above pressure can simply expressed formula P product G L D GThe acceleration affect measured Continued page 92 j7{F41 LI2ii -R4i2S j-- -v - 30NCFoHNv 2O1 UIiFA 11li ILl AIR 6 IL-FUEL IAIR TO ENGINE FIGURE 4 TANK CONFIGURATIONS MAIN TANK AIR Ei HOPPER -PARTIAL VACUUM FUEL TO ENGINE UNIFLOW CHICKEN HOPPER 36 Model Aviation NORMALLY VENTED TO ENGI now cost dollar fuel consistent its home brew good chance could have picked up some water air Theres also chance home brew consistent last batch horrible experience cost two en gines place two Nationals some backyard brew no oil Sure lots smaller fuel distribu tors have good consistent mixes fuel need careful will maintain two gallon cans same fuel side side can run differently seems unlikely muffler could cause inconsistent run except muffler pressure too much too little Experimenting size muffler pressure lines could help some instan ces muffler pressure fitting bad place receiving too much too little pres sure Finally back pressure muf fler may causing engine heat up and/or allowing engine breathe properly good run feel inconsistent runs stem fuel tank fuel lines tank must checked leaks broken tubing clogged lines fuel tubing must go straight line possible pick up tube spray bar No bends twists necessary have removable tank makes much easier adjust tank can moved up down relation spray bar engine can adjusted shims etc recall Bill Werwage inletted mounting beams 1977 Juno could raise engine air plane viewed upright position did get design doubt seriously 25% stunt fliers could plot airfoil mathemati cally accurately scratch doubt have aeronautical design training other what picked up model magazines like sit down sketch out new plane put working drawings using proven wing areas force moment arms tailplane sizes powerplant com ponents Actually canards have seen Nationals finals Open Stunt disguised combat planes have won Walker Cup trophy Ive seen person ever fly Sea Fury Yes know twin-engine stunter placed back 60s 1967 Rich Loomis first Senior best advice can give someone wants depart kit airplane look what works other accom plished fliers well competition over period years sit down draw up couple planes appeal using some full-size plans published planes have Nation als FAI competition adapt rough drawings utilize basic impor tant ingredients must present successful stunt plane wing area related engine size total weight aspect ratio wing force moment-arms both nose tail tailplane size tail vol ume flap size thrust line placement respect wing fuselage side area con trol movement equal unequal wing pan els leading edge sweepback dihedral airfoil size tip configuration Lastly stick design three four versions work out bugs information stunt PAMPA contact Wynn Paul 1640 Maywick Drive Lex Ky. 40504 CL Racing/Lee continued page 36 units acceleration due gravity LDistance measured inches free surface fluid point pressure being measured measured direction force causing acceleration DThe density fluid measured pounds per cubic inch What formula tells us pile up more fluid top pressure feel correspondingly higher model airplane three variables 6-loading due centrifugal force plane flies circle density fuel carried tank dis tance L distance free sur face fuel hole needle valve measured perpendicular line flight Fig illustrates pressure jar water meas uring pressure water various levels jar Note pressure ex hibited independent shape container three variables G L D couple intersting numbers can calculated formula First what kind pressure change would see variable L reduced some value some other value Fig 2 graph shows pressure change water under normal force gravity function depth water much water above point water pressure being meas ured As can seen pressure changes about 0346 psi/in water about psi 10 inches order verify number built simple test apparatus consisted 104 large diameter plastic tubing pressure gauge tachment enabled read pres sures various places column Much relief theoretical values supported reality measured 36 psi bottom column 104 ches water under 1-6 acceleration re sults 36 psi OK much water jar about fuel fuel tank First off have measure G force model hence tank fuel 6 loading can calculated know line length speed plane flying few representative values 6 listed below 6 1467 x MPH2 322 X line length few representative values G listed below MPHGs 525Gs 60 10012731114 10514041228 11015401349 11516841473 12018331604 12519891740 13021511882 13523202030 14024952183 14526762242 ISO28642506 160-flat Goodyear will pulling 1611 6s Slow Rat 160 flat pulling 1409 6s Now crank 6-values first equation along density fuel 0332 lbs/cu find pressure variation 1125-mph Goodyear over /2 psi per slightly less per Slow Rat tank oneinch wide pressure variation fuel level changes full empty will neighborhood pres sure variation will occur regardless whether using pressure fuel system course Slow Rat suction systems allowed psi variation will pressure system Goodyear too its pretty obvious wider tank will result greater variation general rule keep fuel tank narrow possible Tall long OK narrow possible keep pressure change minimum good question ask much does pressure change affect total pressure pressure system order find answer have know pressure created tank using crankcase pressure set up test stand measure found tank pressure untimed crank case tap about 14 psi about 16 psi ball-check used pressure line 92 Model Aviation $ WIN $ USE DAVIS DIESEL CONVERTER AT THE 1978 NATS Fastest Time CL$10000 Highest Time FF$10000 Highest Points /zA Stunt$10000 Davis Diesel Devlopment Inc Box 141 DEPT E MILFORD CT 06460 LiPHONE 203 877-1670 Six eight Db reduction 01 noise engines Proportional volumne expan sion chamber Large exhaust nozzle low back pressure Little no losa power No30109191049 So 30229401939 No 30043001949 xIIbI o 0 5 sod x sI No 304R1991911095 NO 005402940ttl95 NO 30641 45us 41309 NEW/ MUFF-L-IT SERIES Available B C engines REGULAR 1k REAR EX 1/2A MUFFLER Fits COX 049 engInes NO 30099491544 No 30940911549 order find pressure engine sees air have add pressure due centrifugal force can calculated above pressure placed tank pressure line Fig 3 illustrates pressure needle valve function distance needle valve free surface fuel basic assumption crankcase pressure results 14 psi Given /2 psi variation per pressure change fuel level changes signifi cant pressure fuel system three basic non-pressure tank set-ups general use today normally vented tank uni-flow tank chicken-hopper tank designs has different very predictable pressure characteristics modeler has either use allow design Fig 4 shows three types tanks gravity feed intended help visualize effect centrifugal force thinking effect gravity Note normally vented tank will cause pressure vary continuously level fuel tank changes full empty obviously reason kind tank causes rich-to-lean needle setting have encountered case uni-flow tank placement air bleed line im portant pressure seen en gine will equal pressure free surface fuel always level air bleed long actual free surface aboveo bleed air bleed above free surface fuel pressure will change continuously since tank has become normally vented tank bleed out fuel aspect uni-flow tank will cause problems need tank airtight after fuel has put air bleed can work properly tank sealed will act just like nor mally vented tank since precisely what has become chicken-hopper tank uses de mand feed principle tank really two tanks sealed large other normally vented tank small engine draws fuel small tank drawing fuel level down until vent large tank un covered allows bubble air get large tank corresponding quantity fuel flow back small hopper tank process repeats engine uses fuel out small tank chicken hopper has several notable characteristics First since hopper tank usually small pressure varia tion develops fuel used normally quite small desirable attribute Second tank set-up usually exhibits tendency run rich short until pres sure main tank decreases point vent hopper tank starts work Third main tank must airtight chicken hopper tank usu ally results large amount plumb ing install thing common three fuel tank set-ups re quire fuel drawn engine venturi action engine itself fact causes use pressure fuel feed systems events allowed events like Slow Rat Slow Combat pressure systems allowed its properly built installed fuel tank will make break entry Texas domi nant fuel tank set-up somewhat different Ive described above Look picture accompanies column read description knowledge design first used Larry Miller Larry Hoffman Corpus Christi Texas about two years ago general idea mount fuel tank inboard side nose plane causes have seen above significant amount pressure seen engine due centri fugal force tank placement fact plane pictures fuel free surface varies three ches two inches engine draws fuel tank translates pres sure 160 flat 14 psi tank full 94 psi absolutely empty Now tank just about half empty after 35 laps means pres sure engine sees about 12 14 July1978 93 F I9D9 qualities make moaei NATS winner same ones Sunday sport-scale fliers look Exceptional appearance start wth course FW 190s stark sinster shape has always excited modeiers important friendly flying qualities designs have always emphasized safety low speeds FW 190 has herited ability fly 80-90 mph right down near-hover landing wide-track gear makes ideal first tail-dragger Kit features Fuil-size plans showing rado retracting gear installat Color schemes decais THREE different FW l9CsSeparate 16-page instructon oooklet cutaway diagrams in-depth flying hints Diecut machined balsa nylon fttings formed wire cowl canopy etc Span 65 Area 730 Sq 4 6 channel Engine 60 GET ORGANIZED Mores set 4 Siurdy fries holds over 4 years favorite Byft mageorses 4 MAG FILES $495 Send $495 pbs $1 SO postage 50541mg DON INDUSTRIES PO BOX 388-K DOVER NH 03820 psi very nearly what pressure system would yield using untimed crank case pressure real key systems operation use carburetor has very large hole air arranged closed ground no pressure tank due centrifugal forcer open air take advantage tank pressure due centrifugal force have using old Pylon carb 1K/B once supplied old Series 71 rear-rotor 40 put big blob sol der throttle arm thatr does centrifugal force supply pres sure fuel causes carbure tor open take advantage pres sure carb has used weve found order get airplane air until centrifugal force builds up Weve also found must set needle valve air since no reliable way set needle ground have right air tank set-up looks rather wierd does work very well results ability use ven turi large used pressure sys tem corresponding increase en gine performance Bill Lee 2522 Tamarish Lane Missouri City TX 77459 Safe Flying No Accident CL Combat/Johnson continued page 37 Fast Combat Top Ten I Richard Lopez 2 Richard Brasher 3 Richard Stubblefield 4 Bob Burch 5 Chuck Rudner 6 Mike Guthomson 7 Neal Rose 8 George Cleveland 9 Phil Granderson 10 Paul Smith Slow Combat Top Ten I Paul Smith 2 Richard Subblelield 3 Mike Guthomson 4 George Cleveland 5 Andrew Lee 6 Paul Curtis 7 Gil Reedy 8 Chuck Rudner 9 Ed Brzys 10 Joseph Ambrose FAI Combat Top Ten I Neal Rose 2 Richard Imboff 3 Paul Smith 4 Max Mearns 5 Howard Rush 6 Richard Stubblefield 7 Gary Frost 8 Bob Burch 9 Phil Cartier 9 Chuck Rudner Last year received few queries certain well known very compe tent combat fliers list Probably common reason person MACA member question arises list MACA members count wins against other MACA members combat fliers general Others have complained though MACA members limited number contests can enter get points because weather no con tests California Florida Hawaii should have death grip Top Twenty case other factor Southern California fliers combat meets restricted-entry con tests counted toward standings would think objective throughout year would have fun contests best devis ing ways get points usually make pitch MACA end articles think Ill catch ofT guard time owe yourself become knowledgeable about Combat dont fly com petition join MACA send $600 $1000 overseas year member ship along name address MACA Treasurer Patty Sasnett 1443 McKinley Ave Escondido CA 92027 Please state renewal list MACA member responsible joining intention duplicate con test calendar found Model viation would like call attention sev eral contests deserve support first United States Control Line Model Airplane Championships held June 17 18 Winston-Salem North Carolina Bill Pardue has added FAI Combat year condition combat fliers step forward help run event Remember controlline AAAA contest 1978 big gest except Nationals MACA Combat Championships will held 8th 9th July Cincinnati Fast Slow FAI Combat will fea tured will Top Twenty chal lenge may challenge Top Twenty person $500 fee will go MACA treasury Speed Performance will featured both days will consist following Time takeoff 2 fly four level laps 3 3 inside loops 4 Pull out inverted fly four inverted laps 5 3 outside 1oops level flight stop timer 6 Seven level laps IS feet less top speed Score will total number seconds maneuvers plus num 94 Model Aviation CUSTOM TUNED ENGINES COMPETITION ACCESSORIES Cox 049A051 Specialists brochure send 13C stamp Kustom Krattsmanship Brochure Box 2699 Laguna Hjll5r CA 92653 714 830-5162
Edition: Model Aviation - 1978/07
Page Numbers: 36, 92, 93, 94
Control Line. Racing. Bill Lee IT SEEMS areas construction competition can best classified black magic seems flier has own way doing something undoubtedly best way Well want talk about little theory give some equations about fuel tanks shape placement act way flight hope will dis pel some myth surrounds topic First some basic facts weight water very near oz per fluid ounce converts 0346 pounds per cu since fluid ounce 1804 cu OK whos worried about weight water Certainly use very little flying model airplanes Well turns out fuel very near water weight 96 ounce per fluid ounce So want un derstand what goes fuel system can investigate using water know ballpark fuel Listed V-IF IF vj ii 1 -I1W 1 I1I ff11 1 FIGURE 1 WATER IN JAR PRESSURE IS FUNCTION OF DEPTH 0346 0346 IUIIIfIYiILILIiII below some densities various fluids Ounces Lbs Specific fi oz cu Gravity Water Methanol Ucon LB625 Nitromethane Fuel 50% nit ro 100346 810281 960332 1060368 960332 10 81 96 106 96 As can seen table alcohol lighter water nitro heavier oil slightly lighter com bine components make fuel result slightly lighter water about same density oil Now apply numbers few principles physics can help us swer question Any quantity fluid subjected force will exhibit some fixed characteristics important us pressure gradiant within fluid function much fluid piled above pressure can simply expressed formula P product G L D GThe acceleration affect measured Continued page 92 j7{F41 LI2ii -R4i2S j-- -v - 30NCFoHNv 2O1 UIiFA 11li ILl AIR 6 IL-FUEL IAIR TO ENGINE FIGURE 4 TANK CONFIGURATIONS MAIN TANK AIR Ei HOPPER -PARTIAL VACUUM FUEL TO ENGINE UNIFLOW CHICKEN HOPPER 36 Model Aviation NORMALLY VENTED TO ENGI now cost dollar fuel consistent its home brew good chance could have picked up some water air Theres also chance home brew consistent last batch horrible experience cost two en gines place two Nationals some backyard brew no oil Sure lots smaller fuel distribu tors have good consistent mixes fuel need careful will maintain two gallon cans same fuel side side can run differently seems unlikely muffler could cause inconsistent run except muffler pressure too much too little Experimenting size muffler pressure lines could help some instan ces muffler pressure fitting bad place receiving too much too little pres sure Finally back pressure muf fler may causing engine heat up and/or allowing engine breathe properly good run feel inconsistent runs stem fuel tank fuel lines tank must checked leaks broken tubing clogged lines fuel tubing must go straight line possible pick up tube spray bar No bends twists necessary have removable tank makes much easier adjust tank can moved up down relation spray bar engine can adjusted shims etc recall Bill Werwage inletted mounting beams 1977 Juno could raise engine air plane viewed upright position did get design doubt seriously 25% stunt fliers could plot airfoil mathemati cally accurately scratch doubt have aeronautical design training other what picked up model magazines like sit down sketch out new plane put working drawings using proven wing areas force moment arms tailplane sizes powerplant com ponents Actually canards have seen Nationals finals Open Stunt disguised combat planes have won Walker Cup trophy Ive seen person ever fly Sea Fury Yes know twin-engine stunter placed back 60s 1967 Rich Loomis first Senior best advice can give someone wants depart kit airplane look what works other accom plished fliers well competition over period years sit down draw up couple planes appeal using some full-size plans published planes have Nation als FAI competition adapt rough drawings utilize basic impor tant ingredients must present successful stunt plane wing area related engine size total weight aspect ratio wing force moment-arms both nose tail tailplane size tail vol ume flap size thrust line placement respect wing fuselage side area con trol movement equal unequal wing pan els leading edge sweepback dihedral airfoil size tip configuration Lastly stick design three four versions work out bugs information stunt PAMPA contact Wynn Paul 1640 Maywick Drive Lex Ky. 40504 CL Racing/Lee continued page 36 units acceleration due gravity LDistance measured inches free surface fluid point pressure being measured measured direction force causing acceleration DThe density fluid measured pounds per cubic inch What formula tells us pile up more fluid top pressure feel correspondingly higher model airplane three variables 6-loading due centrifugal force plane flies circle density fuel carried tank dis tance L distance free sur face fuel hole needle valve measured perpendicular line flight Fig illustrates pressure jar water meas uring pressure water various levels jar Note pressure ex hibited independent shape container three variables G L D couple intersting numbers can calculated formula First what kind pressure change would see variable L reduced some value some other value Fig 2 graph shows pressure change water under normal force gravity function depth water much water above point water pressure being meas ured As can seen pressure changes about 0346 psi/in water about psi 10 inches order verify number built simple test apparatus consisted 104 large diameter plastic tubing pressure gauge tachment enabled read pres sures various places column Much relief theoretical values supported reality measured 36 psi bottom column 104 ches water under 1-6 acceleration re sults 36 psi OK much water jar about fuel fuel tank First off have measure G force model hence tank fuel 6 loading can calculated know line length speed plane flying few representative values 6 listed below 6 1467 x MPH2 322 X line length few representative values G listed below MPHGs 525Gs 60 10012731114 10514041228 11015401349 11516841473 12018331604 12519891740 13021511882 13523202030 14024952183 14526762242 ISO28642506 160-flat Goodyear will pulling 1611 6s Slow Rat 160 flat pulling 1409 6s Now crank 6-values first equation along density fuel 0332 lbs/cu find pressure variation 1125-mph Goodyear over /2 psi per slightly less per Slow Rat tank oneinch wide pressure variation fuel level changes full empty will neighborhood pres sure variation will occur regardless whether using pressure fuel system course Slow Rat suction systems allowed psi variation will pressure system Goodyear too its pretty obvious wider tank will result greater variation general rule keep fuel tank narrow possible Tall long OK narrow possible keep pressure change minimum good question ask much does pressure change affect total pressure pressure system order find answer have know pressure created tank using crankcase pressure set up test stand measure found tank pressure untimed crank case tap about 14 psi about 16 psi ball-check used pressure line 92 Model Aviation $ WIN $ USE DAVIS DIESEL CONVERTER AT THE 1978 NATS Fastest Time CL$10000 Highest Time FF$10000 Highest Points /zA Stunt$10000 Davis Diesel Devlopment Inc Box 141 DEPT E MILFORD CT 06460 LiPHONE 203 877-1670 Six eight Db reduction 01 noise engines Proportional volumne expan sion chamber Large exhaust nozzle low back pressure Little no losa power No30109191049 So 30229401939 No 30043001949 xIIbI o 0 5 sod x sI No 304R1991911095 NO 005402940ttl95 NO 30641 45us 41309 NEW/ MUFF-L-IT SERIES Available B C engines REGULAR 1k REAR EX 1/2A MUFFLER Fits COX 049 engInes NO 30099491544 No 30940911549 order find pressure engine sees air have add pressure due centrifugal force can calculated above pressure placed tank pressure line Fig 3 illustrates pressure needle valve function distance needle valve free surface fuel basic assumption crankcase pressure results 14 psi Given /2 psi variation per pressure change fuel level changes signifi cant pressure fuel system three basic non-pressure tank set-ups general use today normally vented tank uni-flow tank chicken-hopper tank designs has different very predictable pressure characteristics modeler has either use allow design Fig 4 shows three types tanks gravity feed intended help visualize effect centrifugal force thinking effect gravity Note normally vented tank will cause pressure vary continuously level fuel tank changes full empty obviously reason kind tank causes rich-to-lean needle setting have encountered case uni-flow tank placement air bleed line im portant pressure seen en gine will equal pressure free surface fuel always level air bleed long actual free surface aboveo bleed air bleed above free surface fuel pressure will change continuously since tank has become normally vented tank bleed out fuel aspect uni-flow tank will cause problems need tank airtight after fuel has put air bleed can work properly tank sealed will act just like nor mally vented tank since precisely what has become chicken-hopper tank uses de mand feed principle tank really two tanks sealed large other normally vented tank small engine draws fuel small tank drawing fuel level down until vent large tank un covered allows bubble air get large tank corresponding quantity fuel flow back small hopper tank process repeats engine uses fuel out small tank chicken hopper has several notable characteristics First since hopper tank usually small pressure varia tion develops fuel used normally quite small desirable attribute Second tank set-up usually exhibits tendency run rich short until pres sure main tank decreases point vent hopper tank starts work Third main tank must airtight chicken hopper tank usu ally results large amount plumb ing install thing common three fuel tank set-ups re quire fuel drawn engine venturi action engine itself fact causes use pressure fuel feed systems events allowed events like Slow Rat Slow Combat pressure systems allowed its properly built installed fuel tank will make break entry Texas domi nant fuel tank set-up somewhat different Ive described above Look picture accompanies column read description knowledge design first used Larry Miller Larry Hoffman Corpus Christi Texas about two years ago general idea mount fuel tank inboard side nose plane causes have seen above significant amount pressure seen engine due centri fugal force tank placement fact plane pictures fuel free surface varies three ches two inches engine draws fuel tank translates pres sure 160 flat 14 psi tank full 94 psi absolutely empty Now tank just about half empty after 35 laps means pres sure engine sees about 12 14 July1978 93 F I9D9 qualities make moaei NATS winner same ones Sunday sport-scale fliers look Exceptional appearance start wth course FW 190s stark sinster shape has always excited modeiers important friendly flying qualities designs have always emphasized safety low speeds FW 190 has herited ability fly 80-90 mph right down near-hover landing wide-track gear makes ideal first tail-dragger Kit features Fuil-size plans showing rado retracting gear installat Color schemes decais THREE different FW l9CsSeparate 16-page instructon oooklet cutaway diagrams in-depth flying hints Diecut machined balsa nylon fttings formed wire cowl canopy etc Span 65 Area 730 Sq 4 6 channel Engine 60 GET ORGANIZED Mores set 4 Siurdy fries holds over 4 years favorite Byft mageorses 4 MAG FILES $495 Send $495 pbs $1 SO postage 50541mg DON INDUSTRIES PO BOX 388-K DOVER NH 03820 psi very nearly what pressure system would yield using untimed crank case pressure real key systems operation use carburetor has very large hole air arranged closed ground no pressure tank due centrifugal forcer open air take advantage tank pressure due centrifugal force have using old Pylon carb 1K/B once supplied old Series 71 rear-rotor 40 put big blob sol der throttle arm thatr does centrifugal force supply pres sure fuel causes carbure tor open take advantage pres sure carb has used weve found order get airplane air until centrifugal force builds up Weve also found must set needle valve air since no reliable way set needle ground have right air tank set-up looks rather wierd does work very well results ability use ven turi large used pressure sys tem corresponding increase en gine performance Bill Lee 2522 Tamarish Lane Missouri City TX 77459 Safe Flying No Accident CL Combat/Johnson continued page 37 Fast Combat Top Ten I Richard Lopez 2 Richard Brasher 3 Richard Stubblefield 4 Bob Burch 5 Chuck Rudner 6 Mike Guthomson 7 Neal Rose 8 George Cleveland 9 Phil Granderson 10 Paul Smith Slow Combat Top Ten I Paul Smith 2 Richard Subblelield 3 Mike Guthomson 4 George Cleveland 5 Andrew Lee 6 Paul Curtis 7 Gil Reedy 8 Chuck Rudner 9 Ed Brzys 10 Joseph Ambrose FAI Combat Top Ten I Neal Rose 2 Richard Imboff 3 Paul Smith 4 Max Mearns 5 Howard Rush 6 Richard Stubblefield 7 Gary Frost 8 Bob Burch 9 Phil Cartier 9 Chuck Rudner Last year received few queries certain well known very compe tent combat fliers list Probably common reason person MACA member question arises list MACA members count wins against other MACA members combat fliers general Others have complained though MACA members limited number contests can enter get points because weather no con tests California Florida Hawaii should have death grip Top Twenty case other factor Southern California fliers combat meets restricted-entry con tests counted toward standings would think objective throughout year would have fun contests best devis ing ways get points usually make pitch MACA end articles think Ill catch ofT guard time owe yourself become knowledgeable about Combat dont fly com petition join MACA send $600 $1000 overseas year member ship along name address MACA Treasurer Patty Sasnett 1443 McKinley Ave Escondido CA 92027 Please state renewal list MACA member responsible joining intention duplicate con test calendar found Model viation would like call attention sev eral contests deserve support first United States Control Line Model Airplane Championships held June 17 18 Winston-Salem North Carolina Bill Pardue has added FAI Combat year condition combat fliers step forward help run event Remember controlline AAAA contest 1978 big gest except Nationals MACA Combat Championships will held 8th 9th July Cincinnati Fast Slow FAI Combat will fea tured will Top Twenty chal lenge may challenge Top Twenty person $500 fee will go MACA treasury Speed Performance will featured both days will consist following Time takeoff 2 fly four level laps 3 3 inside loops 4 Pull out inverted fly four inverted laps 5 3 outside 1oops level flight stop timer 6 Seven level laps IS feet less top speed Score will total number seconds maneuvers plus num 94 Model Aviation CUSTOM TUNED ENGINES COMPETITION ACCESSORIES Cox 049A051 Specialists brochure send 13C stamp Kustom Krattsmanship Brochure Box 2699 Laguna Hjll5r CA 92653 714 830-5162