Many us have penchant collecting tables airfoil plotting coordinates reason another collections comprise various books individual pages copied cut various sources generally incomplete will save data sheet presented article will have complete data bank commonly-used NACA airfoils can pluck out whichever need occasion arises Plotting FourDigit Five-Digit ries 1 0 NAC ALTHOUGH plotting procedure somewhat dif ferent ordinary should have no trouble fol lowingthe instructions So afew words will distribution ordinates Yt mean line camber airfoil symmetri said about development air- ordinates Yin mean line iscal shapes have minimum profile drag co foils relate model applica- straight resulting shape called sym-efficient operating zero lift don bearing mind activities metrical mean line curved orvalue coefficient depends thickgenerally go realm Reynolds cambered resulting shapes calledness smoothness shape RN As numbers RN below million variety other names depending onare inclined wind create lift As seen using chart sec- combination thickness camberdrag coefficient increases using cam tions formed combining thickness usedber minimum drag coefficient basic shape can maintained practical purposes fairly high values design lift coefficient DLC four-digit sections designed systematically investigate effects amount camber location point maximum camber thickness distil bution essentially Clark Y Gottingen 398 first two numbers gether denote NACA mean line used first maximum amount cam ber percent chord second location maximum point tenths chord back leading edge last two numbers percent thickness Test results showed ward locations maximum camber somewhat efficient moving minimum drag conditions higher CL values also resulted lower nega tive nose down pitching moment coeffi cients shown chart 12% sections thinner being somewhat higher thicker somewhat lower OOXX sections probably still widely used tail surfaces X4XX sections mostly used wings since gave smoother stall forward maximum camber addition somewhat higher CL max Based data NACA variable density tunnel however LETS NAVE ANoTt4 E[. LOOK TNOEdoes seem significant dif RFO IL C N ARTS F yo rence stalling severity between Continued page 133 42 Model Aviation S KY FOX SPORT FLYER Wing Span Wing Area Length Weight Engine Radio SEE YOUR 54 Inches 620 Sq 43 Inches 55 Lbs 4050 4 Channel DEALER RLA MODELS513 859-7839 P 0 BOX 640 WEST CARROLLTON OHIO 45449 Direct Orders Send check money order pay shipping handling Ohio residents add 6% Sales Tax $8995 trols adjustments its transmitter two adjust stick-centering force lacks Collective Pitch Trim Collective Pitch Curve Adjustments have things presetting belicrank angles adjusting ball snaplinks mind system has features other could use Both long long way Basic Airplane Radio four-functions nine controls Kraft systems flight pack feeding Kraft gyro KPR-8FDS receiver five KPS-24 servos delivers 150 mA servos stationary two servos moving freely easily-duplicated condition current drain jumps 550 mA use 5R900 pack gives about two hours operating time operating conditions better some voltage measurements before flight stop flying instant flight pack voltage drops below 48 VDC under load you ask Both Kraft Airtronics transmitter have built-in ESVs Flight Pack both come long cord plugs helicopters Charging Jack purpose assess ing flight pack voltage Use before flight know its little inconvenient carry because nei ther transmitter provides storage packet test cords So make yourself no excuse will undo crash damage Ive done little testing now meters red-lined 48 volts needle drops below point head charger Never mind 44 volts stuff. thats charge exhausted basic continuous drain Helicopter gyro over 150 mA flight time remaining after 47 volts has reached desperately shortI estimate generally less time burn tank fuel Baron 20 tank lasts 10 minutes flight Heli Boy tank lasts 27 minutes could exhaust batteries flight either case after youve lifted off 47 volts speak experience Dont neglect transmitter batteries either Kraft strongly advises stop flying transmitter pack reaches 96 volts judging way system degenerated let run down below point ground tests agree dont like built-in meters alternatives ESVs Ex panded-Scale Voltmeters built-in load resistors available ac cessory market Just sure use some thing Ive asked Which better Synthe sized RF PCM no better case because different things both can used same transmitter fact Ill very surprised Futaba Circus dont add synthe sizer PCM sets next year George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 AirfoilslBrownlee Continued page 42 symmetrical cambered sections RN below million showing smooth stall tendency Large negative pitching moments undesirable higher efficient values CL unless center gravity located behind center pressure wing Otherwise tall will have develop down load trim wing will turn have lift addition aircraft weight added induced drag resulting can substantial five-digit sections devised solve problem retaining same thickness distribution changing equations mean line first three numbers together denote NACA mean line sections variously cam bered DLC 015 times first number second two numbers gether twice distance percent Qf chord point maximum camber last two numbers again thick ness results successful showing very low pitching moments particularly 18-21 07o thickness range Another series 1 middle place 0 devised give theoretical zero pitching moment used sections have reputation violent stalls full scale should tame realm shape basic thickness distri bution four- five-digit sections results minimum pressure maximum velocity air flow 75 1007o back leading edge RN 9 10 million range flow turbulent over about 80-85% surface well below flight RN large fast aircraft objective 6-series sec tions develop basic thickness shapes would move minimum pressure point far back possible provide controlled drop pressure trigger premature transition laminar turbulent flow 6- merely separates sections 1- through 5- 7- 8-series second number denotes minimum pressure point tenths chord basic thickness form third number either following comma wntten subscript denotes extent above below DLC tenths low drag bucket range function thickness will about two 15% three 18% etc notation omit ted basic thicknesses below 12070 subscript ordinates represent later devel opment efforts first number after dash 10 times DLC last two thick ness either whole November1984 133 Engineered tne sport moacler mind TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation
Edition: Model Aviation - 1984/11
Page Numbers: 42, 133, 134
Many us have penchant collecting tables airfoil plotting coordinates reason another collections comprise various books individual pages copied cut various sources generally incomplete will save data sheet presented article will have complete data bank commonly-used NACA airfoils can pluck out whichever need occasion arises Plotting FourDigit Five-Digit ries 1 0 NAC ALTHOUGH plotting procedure somewhat dif ferent ordinary should have no trouble fol lowingthe instructions So afew words will distribution ordinates Yt mean line camber airfoil symmetri said about development air- ordinates Yin mean line iscal shapes have minimum profile drag co foils relate model applica- straight resulting shape called sym-efficient operating zero lift don bearing mind activities metrical mean line curved orvalue coefficient depends thickgenerally go realm Reynolds cambered resulting shapes calledness smoothness shape RN As numbers RN below million variety other names depending onare inclined wind create lift As seen using chart sec- combination thickness camberdrag coefficient increases using cam tions formed combining thickness usedber minimum drag coefficient basic shape can maintained practical purposes fairly high values design lift coefficient DLC four-digit sections designed systematically investigate effects amount camber location point maximum camber thickness distil bution essentially Clark Y Gottingen 398 first two numbers gether denote NACA mean line used first maximum amount cam ber percent chord second location maximum point tenths chord back leading edge last two numbers percent thickness Test results showed ward locations maximum camber somewhat efficient moving minimum drag conditions higher CL values also resulted lower nega tive nose down pitching moment coeffi cients shown chart 12% sections thinner being somewhat higher thicker somewhat lower OOXX sections probably still widely used tail surfaces X4XX sections mostly used wings since gave smoother stall forward maximum camber addition somewhat higher CL max Based data NACA variable density tunnel however LETS NAVE ANoTt4 E[. LOOK TNOEdoes seem significant dif RFO IL C N ARTS F yo rence stalling severity between Continued page 133 42 Model Aviation S KY FOX SPORT FLYER Wing Span Wing Area Length Weight Engine Radio SEE YOUR 54 Inches 620 Sq 43 Inches 55 Lbs 4050 4 Channel DEALER RLA MODELS513 859-7839 P 0 BOX 640 WEST CARROLLTON OHIO 45449 Direct Orders Send check money order pay shipping handling Ohio residents add 6% Sales Tax $8995 trols adjustments its transmitter two adjust stick-centering force lacks Collective Pitch Trim Collective Pitch Curve Adjustments have things presetting belicrank angles adjusting ball snaplinks mind system has features other could use Both long long way Basic Airplane Radio four-functions nine controls Kraft systems flight pack feeding Kraft gyro KPR-8FDS receiver five KPS-24 servos delivers 150 mA servos stationary two servos moving freely easily-duplicated condition current drain jumps 550 mA use 5R900 pack gives about two hours operating time operating conditions better some voltage measurements before flight stop flying instant flight pack voltage drops below 48 VDC under load you ask Both Kraft Airtronics transmitter have built-in ESVs Flight Pack both come long cord plugs helicopters Charging Jack purpose assess ing flight pack voltage Use before flight know its little inconvenient carry because nei ther transmitter provides storage packet test cords So make yourself no excuse will undo crash damage Ive done little testing now meters red-lined 48 volts needle drops below point head charger Never mind 44 volts stuff. thats charge exhausted basic continuous drain Helicopter gyro over 150 mA flight time remaining after 47 volts has reached desperately shortI estimate generally less time burn tank fuel Baron 20 tank lasts 10 minutes flight Heli Boy tank lasts 27 minutes could exhaust batteries flight either case after youve lifted off 47 volts speak experience Dont neglect transmitter batteries either Kraft strongly advises stop flying transmitter pack reaches 96 volts judging way system degenerated let run down below point ground tests agree dont like built-in meters alternatives ESVs Ex panded-Scale Voltmeters built-in load resistors available ac cessory market Just sure use some thing Ive asked Which better Synthe sized RF PCM no better case because different things both can used same transmitter fact Ill very surprised Futaba Circus dont add synthe sizer PCM sets next year George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 AirfoilslBrownlee Continued page 42 symmetrical cambered sections RN below million showing smooth stall tendency Large negative pitching moments undesirable higher efficient values CL unless center gravity located behind center pressure wing Otherwise tall will have develop down load trim wing will turn have lift addition aircraft weight added induced drag resulting can substantial five-digit sections devised solve problem retaining same thickness distribution changing equations mean line first three numbers together denote NACA mean line sections variously cam bered DLC 015 times first number second two numbers gether twice distance percent Qf chord point maximum camber last two numbers again thick ness results successful showing very low pitching moments particularly 18-21 07o thickness range Another series 1 middle place 0 devised give theoretical zero pitching moment used sections have reputation violent stalls full scale should tame realm shape basic thickness distri bution four- five-digit sections results minimum pressure maximum velocity air flow 75 1007o back leading edge RN 9 10 million range flow turbulent over about 80-85% surface well below flight RN large fast aircraft objective 6-series sec tions develop basic thickness shapes would move minimum pressure point far back possible provide controlled drop pressure trigger premature transition laminar turbulent flow 6- merely separates sections 1- through 5- 7- 8-series second number denotes minimum pressure point tenths chord basic thickness form third number either following comma wntten subscript denotes extent above below DLC tenths low drag bucket range function thickness will about two 15% three 18% etc notation omit ted basic thicknesses below 12070 subscript ordinates represent later devel opment efforts first number after dash 10 times DLC last two thick ness either whole November1984 133 Engineered tne sport moacler mind TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation
Edition: Model Aviation - 1984/11
Page Numbers: 42, 133, 134
Many us have penchant collecting tables airfoil plotting coordinates reason another collections comprise various books individual pages copied cut various sources generally incomplete will save data sheet presented article will have complete data bank commonly-used NACA airfoils can pluck out whichever need occasion arises Plotting FourDigit Five-Digit ries 1 0 NAC ALTHOUGH plotting procedure somewhat dif ferent ordinary should have no trouble fol lowingthe instructions So afew words will distribution ordinates Yt mean line camber airfoil symmetri said about development air- ordinates Yin mean line iscal shapes have minimum profile drag co foils relate model applica- straight resulting shape called sym-efficient operating zero lift don bearing mind activities metrical mean line curved orvalue coefficient depends thickgenerally go realm Reynolds cambered resulting shapes calledness smoothness shape RN As numbers RN below million variety other names depending onare inclined wind create lift As seen using chart sec- combination thickness camberdrag coefficient increases using cam tions formed combining thickness usedber minimum drag coefficient basic shape can maintained practical purposes fairly high values design lift coefficient DLC four-digit sections designed systematically investigate effects amount camber location point maximum camber thickness distil bution essentially Clark Y Gottingen 398 first two numbers gether denote NACA mean line used first maximum amount cam ber percent chord second location maximum point tenths chord back leading edge last two numbers percent thickness Test results showed ward locations maximum camber somewhat efficient moving minimum drag conditions higher CL values also resulted lower nega tive nose down pitching moment coeffi cients shown chart 12% sections thinner being somewhat higher thicker somewhat lower OOXX sections probably still widely used tail surfaces X4XX sections mostly used wings since gave smoother stall forward maximum camber addition somewhat higher CL max Based data NACA variable density tunnel however LETS NAVE ANoTt4 E[. LOOK TNOEdoes seem significant dif RFO IL C N ARTS F yo rence stalling severity between Continued page 133 42 Model Aviation S KY FOX SPORT FLYER Wing Span Wing Area Length Weight Engine Radio SEE YOUR 54 Inches 620 Sq 43 Inches 55 Lbs 4050 4 Channel DEALER RLA MODELS513 859-7839 P 0 BOX 640 WEST CARROLLTON OHIO 45449 Direct Orders Send check money order pay shipping handling Ohio residents add 6% Sales Tax $8995 trols adjustments its transmitter two adjust stick-centering force lacks Collective Pitch Trim Collective Pitch Curve Adjustments have things presetting belicrank angles adjusting ball snaplinks mind system has features other could use Both long long way Basic Airplane Radio four-functions nine controls Kraft systems flight pack feeding Kraft gyro KPR-8FDS receiver five KPS-24 servos delivers 150 mA servos stationary two servos moving freely easily-duplicated condition current drain jumps 550 mA use 5R900 pack gives about two hours operating time operating conditions better some voltage measurements before flight stop flying instant flight pack voltage drops below 48 VDC under load you ask Both Kraft Airtronics transmitter have built-in ESVs Flight Pack both come long cord plugs helicopters Charging Jack purpose assess ing flight pack voltage Use before flight know its little inconvenient carry because nei ther transmitter provides storage packet test cords So make yourself no excuse will undo crash damage Ive done little testing now meters red-lined 48 volts needle drops below point head charger Never mind 44 volts stuff. thats charge exhausted basic continuous drain Helicopter gyro over 150 mA flight time remaining after 47 volts has reached desperately shortI estimate generally less time burn tank fuel Baron 20 tank lasts 10 minutes flight Heli Boy tank lasts 27 minutes could exhaust batteries flight either case after youve lifted off 47 volts speak experience Dont neglect transmitter batteries either Kraft strongly advises stop flying transmitter pack reaches 96 volts judging way system degenerated let run down below point ground tests agree dont like built-in meters alternatives ESVs Ex panded-Scale Voltmeters built-in load resistors available ac cessory market Just sure use some thing Ive asked Which better Synthe sized RF PCM no better case because different things both can used same transmitter fact Ill very surprised Futaba Circus dont add synthe sizer PCM sets next year George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 AirfoilslBrownlee Continued page 42 symmetrical cambered sections RN below million showing smooth stall tendency Large negative pitching moments undesirable higher efficient values CL unless center gravity located behind center pressure wing Otherwise tall will have develop down load trim wing will turn have lift addition aircraft weight added induced drag resulting can substantial five-digit sections devised solve problem retaining same thickness distribution changing equations mean line first three numbers together denote NACA mean line sections variously cam bered DLC 015 times first number second two numbers gether twice distance percent Qf chord point maximum camber last two numbers again thick ness results successful showing very low pitching moments particularly 18-21 07o thickness range Another series 1 middle place 0 devised give theoretical zero pitching moment used sections have reputation violent stalls full scale should tame realm shape basic thickness distri bution four- five-digit sections results minimum pressure maximum velocity air flow 75 1007o back leading edge RN 9 10 million range flow turbulent over about 80-85% surface well below flight RN large fast aircraft objective 6-series sec tions develop basic thickness shapes would move minimum pressure point far back possible provide controlled drop pressure trigger premature transition laminar turbulent flow 6- merely separates sections 1- through 5- 7- 8-series second number denotes minimum pressure point tenths chord basic thickness form third number either following comma wntten subscript denotes extent above below DLC tenths low drag bucket range function thickness will about two 15% three 18% etc notation omit ted basic thicknesses below 12070 subscript ordinates represent later devel opment efforts first number after dash 10 times DLC last two thick ness either whole November1984 133 Engineered tne sport moacler mind TIDEWATER ENGR & MACH Co I4~ PO B0X1135BASTROP LA 71220 MICROMOTORSPHONE 318- 281-2460US DISTRIBUTOR MARINE & CAR ENGINE SPECIALS P-21 Car SE$6500P21 Marine SE$6500P65 Marine $9000 P-21 Car RE$6500P-21 Marine RE$6500P80 Marine $11000 P-21 Buggy SE$6500 P-21 Delta$7500P-45 Marine$7800P90 Marine $14000 AERO ENGINESPECIALS P-21 SE$5000P-45 SE$6000P-80 SE$9000 P21 RE$5500P60 SE$8500P-80 RE$9500 P-40 $6500P60 RE$9000P80 Duct Fan $10000 P-40 SE$5800 P-4b Duct Fan$7500P-65 Duct Fan $9500 TWO NEW MARINE ENGINES P45 Mar-Disc Rotor Valve $8500 P90 Mar-Disc Rotor Valve New Carb $14000 number value enclosed paren theses thickness ordinates directly scalable other exact ordinates can scaled make 12% sec tions charts will correctly 6X X12 Otherwise will 6X, z XXX sections smooth sections superi drag very high RN have somehwat lower CL max far superior high Mach numbers delaying force divergence significantly changing lift moment characteristics severely high subsonic speeds have rather large negative pitching mo ments normally used fairly low CL moment can designed out part combining swept wings washout original 1series sections 16-XXX shapes used propellers because better performance high Mach numbers commonly called 16- series airfoils RN about 12 million mini mum profile drag sections will about same four- five-digit sections same thickness Below suffer earlier laminar separa tion higher drag shapes down RN about 70 thousand below drag airfoils becomes mostly pressure drag due laminar separation no reason use sec tions model application other scale fidelity make nice flying wings however relatively sharp leading edges have caused no problems variety scratchbuilt planes conclude hoped tables can future practical use comments have clear interest information condensed primarily Theory Wing Sections Abbott von Doenhoff RC AerobaticslVan Putte Continued page 45 want go remainder turn almost like sailboat irons Whyif doesnt know wind blowing think virtually questions contained Allan Kass letter lot other letters received can answered considering frame ref erence observer fly ing RC usually standing ground attempting make air plane fly maneuvers prescribed man ner regardless wind blowing may have heard about danger ous downwind turn downwind turn 1800 turn started airplane heading downwind Usually turn starts out right little past halfway around airplane stalls out crashes Basically its because pilot crashed wind con tributing factor pilots faulty understanding effects wind causes stall crash Figure 1 shows top view l8O turn both steady wind wind downwind assumed control inputs same both cases effect wind can have move ground track airplane downwind relative no wind track movement ground track function fast wind blowing long has since turn started hash marks respective turns equal time crements Since effect wind constant its effect ground track constant additive other words points B B certain distance apart points C C will twice far apart points D D will three times far apart looks pretty wild doesnt Well pilot trying perform turn looks like no-wind gets upset starts go astray course stand ard correction increase roll angle pull Up elevator track still doesnt look right pilot keeps creasing roll angle pulling Up elevator Surpriselthe airplane just stalled out Its known accelerated stall stall occurs airplane puffing lot Gs isnt like normal stall Since airplane high speed stall happens very abruptly airplane often crashes before pilot can anything way take another look track airplane wind does look like reluctant come around wind until last part turn doesnt no magic involved observers view turn appears indicate strange things happening because observer fixed airplane moving relative wind youd like another thrill take look Figure 2 airplane starts 180 0turn heading upwind comparison same turn shown no-wind situation identical control input Again theres no magic involved fixed observer airplane again appears doing strange things No wonder beginners often get shook make kind turn airplane appears jump back Strange things happen loops too Ill cover later column Thats enough effects wind month heard about costly crash think would valuable lesson us planning change RC equipment new frequencies seems flier took equipment repairman routine maintenance have frequency changed got back assumed equip ment top shape new fre quency bill didnt say specifically what done equipment went contest got shot down because repairman never changed fre quency fault dont know have frequency change future Ill make sure bill dicates what done mystery plane appeared September issue El Gringo 60-size Slicker according Bill Dennis Amarillo TX Bill used trike gear 40-size Slicker place 1972 Canadian Nats Rebel Rally Jacksonville FL way Bill would like modelers interested plans old Stormer IV know has available $12 set Write Sky Fllte Models 20 Windsor Amarillo TX 79106 being written just before 84 134 Model Aviation