echniquc EVERYONE wants use cheapest lightat battery pack possible So figure what size pack choose classical method invented rubber-motor experts know drill wind til breaksthen back off turn two counterpart RC guy uses what has until crash buys next larger size replace Its exciting way separate good stuff trash little hard model mathematician knows have multiply average operating current desired operating time find necessaty battery capacity problem finding out AMPS 3 IOLE 0 what average operating current typical RC situation operating system consists 500maH battery pack receiver switch harness four servos same type cases receiver idles about 2Oma servos idle 5 15 ma run free about 120ma stall 450ma observe combination can flown about two hours using 40- 60powered model hacking around usual sport-flying way hook stopwatch transmitter can keep track ON time use battery tester find out whats left battery return home learn average operating current situation about 260ma Now know operating current can vary idle stall current servo multiplied number servos use also know servos spend least much time idle doing work work depends loads servo must over come important point no servo can draw less idle current So its obvious operating current made up two compo nents idle currentwhich constant drain easy calculate working currentwhich extremely vari able hard calculate Schematic ESV-shunt make match characteristics system use three big servos regular onelike Quarter Scale job instance Operating Current Idle Current ing Currenteq 1 Going back paragraph estimate average operating current keeping few records dumping rest charge battery tester soon discover something like Average operating current a Idle current receiver plus 4 x iSma servos 8Oma mfrs data measure Therefore average working current 260- 80 l8Oma Which peculiar coincidence turns Out 15 x free running current average servo Estimated Working Current FreeRunning Currenteq 2 past two columns have urging calculate size servo need rather following Crash Replace school design gave tools calculate what need evaluate manufacturers literature select effi cient servo purposes Now well assume have decided build larger model have average kind RC system have decided need use three World Engines S-16 servos Lets see long battery will last keep flying same way keep using SOOmaH battery pack caine system Sample Problem No 1 Replace 3 servos S-I 6s 1 Compute system idle current Receiver 20 1 regular servo 15 Three 5-16 @ 8ma 24 59ma 2 Estimate working current case would consider aileron elevator servos S-16 therefore working current 400 ma 3 Estimate Operating Current 59 659ma 4 Estimate Operating Time SOOmah 59ma hours 45 minutes can hear screams starting Obviously picked S-16s make point powerful servos need powerful batteries point would just valid KPS-20H Atlas Chevron Magnum etc get large packs what size buy first part question easy answer since manufacturers offer large packs show pictures Ace RC NI-CD pack contains batteries rated 12 AmpHr World Engines pack rated 16 Amp-Hr should aware fact RC systems generally use batteries rated capacity discharging C/2 rate What mean World Engines 16 Amp-Hr pack rated deliver 16 Amp-Hr discharged 8 Amps 12 Amp-Hr Ace NI-CD pack rated 6 Amp rate Use either above 22 Model Aviation George M Myers lVisra-vi11keouS CUCrr f-oc1e OJe-1nq CUt4-1 J- TlE Figuring battery capacity need know much current system draws long its used per flight could look battery drain over period time would look some thing like World Engines S-16 servo its 16 amp-hour battery pack Below erence equipment Kraft KPS-15 servo 500maH pack performance differences much larger physical sizes would lead expect George couldnt resist Radio Shack stopwatch saw itthe color matches customized Ace Silver Seven transmitter watch used assist record-keeping connection gathering data current consumption airborne system Its also natural Sailplane Pylon Racing contests problem Mounted position polarizer screen LCD readout crossed Georges polarized sunglasses cant read flying repositioning transmitter situation fly modified system usual way will operate usual two hours above discussion related general problem does gather data own spec fic problem ideal situation would measure current demand flight back described tool called PLC 5000 did just works too delicate just stick airplane fly time local experimenter has come up durable digital device Flite * Cycle serves same purpose show photo proto type just will see its expensive isnt production now may never because will have sell over $100 have working in-flight recorder myself thats expensive also friends working telemetry system uses NE5044 chip multiplex several channels information will expensive solution may show up construc tion article days Ive heard tales other types instrumentation nothing publish have something working want share let editor know about Academy means society promotion science case science Model Aeronautics Lacking specific instrumentation best com mon approach started column wit fly known mission freshly charged batteries dump rest charge battery tester Compute average operating current subtracting dumped charge full charge dividing result mission time example might take off 100 loops land record elapsed time change battery packs next flight might 100 snap-rolls Change batteries agaln go back forth over field 100 times constant altitude Change batteries again make 100 circles convenient dia meter constant altitude Now go home discharge packs data will able estimate energy required straightand-level flight turns loops rolls data can estimate energy required mission have mind formula Average Operating Current x Operating Time ery Capacityeq 3 Figuring out what want half battle Measuring what youve got other half will find battery testers market draw about 250ma discharging battery packs value set analysis above Its pretty good flight packs little fast transmitter packs Transmit ters usually draw constant 1 3Oma Transmit ter current doesnt change significant amount move sticks would accurate discharge trans mitter packs 1 3Oma did youd wait four hours transmitter test two hours flight pack test Battery tester design ers figure its less confusing have both packs take about same time test So everyone gets used idea new battery pack tests 120 minutes time gets shorter pack gets older start drawing much larger currents test really begins lie As example could take ESV Expanded Scale Voltmeter stopwatch add am meter few resistors start investi gating Most ESYs draw about 250ma can see much yours draws putting am meter battery leads Now want test higher current need shunt across ESV power resistor 20 ohm resistor rated 2 watts put across ESV terminals will draw another 250ma approximately flight pack ammeter will show exactiy much current drawn Now actually perform test have suggested will find doubling dis charge current does cut discharge time half always get less half time Continued page 103 May1981 23 FliteCycle circuit board finished itemcompared quarter reference few will available mid-igal Contact UST Systems Suite 200 555 Broadhollow Rd Melville NY 11747 interested participating its development lump line between Ace RC NI-CD pack LR Taylor Super Power Panel isa simple 10 ohm 10 watt resistor wired across set Deans connectors connector reversed accommodate different wiring schemes battery pack power panels ESV resistor place ESV reads slightly less 47 VDC Removing resistor jumpathe voltage readingto485 VDC inthis particularcase maycalculatethatthe battery packs resistance state charge approximately 1/3 ohm ft 3/1 6-in flat rubber 100 ft I0-lb-test fishing line old antenna ribbon streamer place usual parachute optional tow hook shown plan worked very well yeilded better results desert hand-launching am sure would better twice length rubber line Maybe am just lazy Slope Soaring much liking especially late lazy afternoons wind down whisper just few Gliders left slopejust barely scratching out flight Zephyr really shines always last plane forced land can tossed up 50 ft above ridge just gentlest breezes will permit several passes problem very well yielded better results desert because youre still flying cant stay out brush down slope ridge Balance very important gentle forgiving little bird slow flight hand-launching speed range quite broad hand-launching easily going 50 mph launch leaves hand about 10 mph light lift can trimmed both conditions Thought would never ask get balance correct place will trimmed both conditions anything between throw up should go straight rock zooms up have too nose-heavy thats right nose-heavy too tail-heavy will tend arc downward slight dive both cases assumes have model adjusted relatively slow hands-off glide Without getting lengthy aerodynamic discussion extra nose weight causes extra up-elevator trim just keep model level during slow flight throw hard above trim speed up-elevator trim causes nose pull up can also test same thing gliding higher up Start slow-trimmed glide Gradually push nose down hold control stick same position model builds up speed tends pull out dive too nose-heavy dive steepens tail-heavy correct balance should continue same diving attitude started correct balance point Zephyr will loops rolls inverted flight dont expect inverted flight undercambered airfoil good upright flight decent wind slope should able maintain altitude inverted have Zephyr mastered make control surfaces sensitive travel better real fun Radio Technique/Myers Continued page 23 reason judge end-of-charge point voltage small part battery voltage lost across ammeter larger part lost inside battery batteries have internal resistance new AA-size nickle-cadmium battery will show about 035 ohms operating about 75% full charge As charge exhausted resistance increases until reaches about 100 ohms battery shows terminal voltage around 10 VDC numbers look small until consider multiply four get pack resistance add some ohms account welded tabs soldered joints wire plug Figure flight pack will vary depending its state charge Multiply resistance current Continued page 106 May1981 103 Shes surprisingly easy handle. can really get up go. WING SPAN 56 rfster LENGTH 39 WEIGHT 5-6 LBS POWER 40 C0VERITE 420 BABYLON RD 1-IORSHAM PA 19044 1YEAR WARRANTY WARRANTY OR SERVICE-K WORK CAR RE DONE UT RUQOR Hf 0 OR RY YOUR** REAREST ECIIO-KIORITZ PRODUCTS DEALERK** K** Exhaust Manifold Velocity Stack Kits Available * being drawn find out much voltage lost inside battery Volts x Ohms eq 4 Lets say during flight enough servos move against enough load draw 1 amp Lets also say battery partially discharged showing us 50 volts internal resis tance lost voltage will volt drops terminal voltage 4875 VDC No problem Now move over other end curve battery showing 47 VDC resistance has risen Ys ohm Lost voltage now 375 VDC terminal voltage drops 43 25 VDC consider 44 VDC end useful charge analysis tells us battery done day Suppose test ESY draws nominal 250ma voltage lost 047 VDC improper test shows 465 VDC ESV figure fine shape another flight think get point want compare Apples Apples instead Apples Oranges need shunt ESV enough external resistance make measure situation face flying larger servos Id permanently mount 10 ohm 10 watt resistor across plug THE RISING STAR IN GIANT SCALE ENGINES 24 CU inch 32 HP 8000 RPM 6/s lbs 03 Ring Piston Ball Bearings Crank Sealed Points VAYSHPPNG ON PRE-PAID ORDER * * Dealer Inquiries * * Welcome KK ROUSH MFG P0 Box 251 Sandyville OH 44671 Ph 216/866-9462 216/484-4374 see sketch ESV used test system powers three World Engines S-16 servos youre using something else now know figure similar shunt needs Lest ye think Im picking World Engines let point out real message column follows time decide something out ordinary consider consequences Some pretty subtle ESV have learned love trust designed around different situation face fly anything four ordinary servos number larger-than-ordinary ser vos Ive shown estimate average working current compensate ESV Ive also shown larger servos need larger batteries figure what need ratings came returned Christmas vacation 10 letters waiting responded request rating previous columns took rankings provided put point scores columns reverse order preference respondent listed five columns assigned five points most-liked column point least 10 columns mentioned top column got 10 points etc Based limited sampling top column 1980 September 80 column MEN C50/4 charger barely nosed out three columns Ace Silver Seven transmitter Third place went WRAMS show coverage didnt expect Five letters asked information Dual Mixer 10 letters expressed preference technical content scoring system biased favor people rated large number columns Doing statistics differently tried assigning scores order preference summing scores dividing number entries against item Using method lowest score greater zero best Dual Mixer column October 80 walked away rest MEN column came second Any way look respondents liked scientific articles show interest something unusual Most seemed want details Whats preference dont vote no will know Keep letters flowing George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 Letteri ng/Woaver Continued page 24 type used commercial art trade setting headlines available hundreds styles sizes Directions using press type explained catalogs put out various manufacturers Zip-A-Tone Formatt Letraset short simply draw straight line sheet paper position appropriate letters numbers line rub area stylus such pencil ball-point pen etc Remove plastic sheet Presto. beautiful master Use master make Xerox copies youre ready proceed illustrated steps way press type can used directly model Some care must exercised rub too hard ruin surface model After application number press type must fuel-proofed Light coats sprayed-on clear dope new fuel-proofing clear finishes will work long lightly apply first few coats SAFE FLYING IS NO ACCIDENT Features r Specifications s=-r ftfl~Span 86 II 1P111k i1I ITI'1 11111k IIgArea 1245sq-. IIIWeight 12 Engine 91 Cline drive unit elevators vertical fin rudder 1 Seperate detachable presheeted wing panels 2 Preassembiled fuselage frame 3 Preassembiled stabilizer IOC L 4 Epoxy Glass cowl wheelpants 5 Formed hatch clear canopy 6 Aluminum landing gear DEALER & 015 AWL OA INQUIRIES E Fronton St Brownsv lie TX 7852015121 5413867J Wayne Ulerys outstanding design Leo Loudenslagers Laser 200 geared 90 offered Model Merchant nearly constructed model critical fuselage & control surfaces framing wing sheeting has done Just some finish up ready fly best available 106 Model Aviation
Edition: Model Aviation - 1981/05
Page Numbers: 22, 23, 103, 106
echniquc EVERYONE wants use cheapest lightat battery pack possible So figure what size pack choose classical method invented rubber-motor experts know drill wind til breaksthen back off turn two counterpart RC guy uses what has until crash buys next larger size replace Its exciting way separate good stuff trash little hard model mathematician knows have multiply average operating current desired operating time find necessaty battery capacity problem finding out AMPS 3 IOLE 0 what average operating current typical RC situation operating system consists 500maH battery pack receiver switch harness four servos same type cases receiver idles about 2Oma servos idle 5 15 ma run free about 120ma stall 450ma observe combination can flown about two hours using 40- 60powered model hacking around usual sport-flying way hook stopwatch transmitter can keep track ON time use battery tester find out whats left battery return home learn average operating current situation about 260ma Now know operating current can vary idle stall current servo multiplied number servos use also know servos spend least much time idle doing work work depends loads servo must over come important point no servo can draw less idle current So its obvious operating current made up two compo nents idle currentwhich constant drain easy calculate working currentwhich extremely vari able hard calculate Schematic ESV-shunt make match characteristics system use three big servos regular onelike Quarter Scale job instance Operating Current Idle Current ing Currenteq 1 Going back paragraph estimate average operating current keeping few records dumping rest charge battery tester soon discover something like Average operating current a Idle current receiver plus 4 x iSma servos 8Oma mfrs data measure Therefore average working current 260- 80 l8Oma Which peculiar coincidence turns Out 15 x free running current average servo Estimated Working Current FreeRunning Currenteq 2 past two columns have urging calculate size servo need rather following Crash Replace school design gave tools calculate what need evaluate manufacturers literature select effi cient servo purposes Now well assume have decided build larger model have average kind RC system have decided need use three World Engines S-16 servos Lets see long battery will last keep flying same way keep using SOOmaH battery pack caine system Sample Problem No 1 Replace 3 servos S-I 6s 1 Compute system idle current Receiver 20 1 regular servo 15 Three 5-16 @ 8ma 24 59ma 2 Estimate working current case would consider aileron elevator servos S-16 therefore working current 400 ma 3 Estimate Operating Current 59 659ma 4 Estimate Operating Time SOOmah 59ma hours 45 minutes can hear screams starting Obviously picked S-16s make point powerful servos need powerful batteries point would just valid KPS-20H Atlas Chevron Magnum etc get large packs what size buy first part question easy answer since manufacturers offer large packs show pictures Ace RC NI-CD pack contains batteries rated 12 AmpHr World Engines pack rated 16 Amp-Hr should aware fact RC systems generally use batteries rated capacity discharging C/2 rate What mean World Engines 16 Amp-Hr pack rated deliver 16 Amp-Hr discharged 8 Amps 12 Amp-Hr Ace NI-CD pack rated 6 Amp rate Use either above 22 Model Aviation George M Myers lVisra-vi11keouS CUCrr f-oc1e OJe-1nq CUt4-1 J- TlE Figuring battery capacity need know much current system draws long its used per flight could look battery drain over period time would look some thing like World Engines S-16 servo its 16 amp-hour battery pack Below erence equipment Kraft KPS-15 servo 500maH pack performance differences much larger physical sizes would lead expect George couldnt resist Radio Shack stopwatch saw itthe color matches customized Ace Silver Seven transmitter watch used assist record-keeping connection gathering data current consumption airborne system Its also natural Sailplane Pylon Racing contests problem Mounted position polarizer screen LCD readout crossed Georges polarized sunglasses cant read flying repositioning transmitter situation fly modified system usual way will operate usual two hours above discussion related general problem does gather data own spec fic problem ideal situation would measure current demand flight back described tool called PLC 5000 did just works too delicate just stick airplane fly time local experimenter has come up durable digital device Flite * Cycle serves same purpose show photo proto type just will see its expensive isnt production now may never because will have sell over $100 have working in-flight recorder myself thats expensive also friends working telemetry system uses NE5044 chip multiplex several channels information will expensive solution may show up construc tion article days Ive heard tales other types instrumentation nothing publish have something working want share let editor know about Academy means society promotion science case science Model Aeronautics Lacking specific instrumentation best com mon approach started column wit fly known mission freshly charged batteries dump rest charge battery tester Compute average operating current subtracting dumped charge full charge dividing result mission time example might take off 100 loops land record elapsed time change battery packs next flight might 100 snap-rolls Change batteries agaln go back forth over field 100 times constant altitude Change batteries again make 100 circles convenient dia meter constant altitude Now go home discharge packs data will able estimate energy required straightand-level flight turns loops rolls data can estimate energy required mission have mind formula Average Operating Current x Operating Time ery Capacityeq 3 Figuring out what want half battle Measuring what youve got other half will find battery testers market draw about 250ma discharging battery packs value set analysis above Its pretty good flight packs little fast transmitter packs Transmit ters usually draw constant 1 3Oma Transmit ter current doesnt change significant amount move sticks would accurate discharge trans mitter packs 1 3Oma did youd wait four hours transmitter test two hours flight pack test Battery tester design ers figure its less confusing have both packs take about same time test So everyone gets used idea new battery pack tests 120 minutes time gets shorter pack gets older start drawing much larger currents test really begins lie As example could take ESV Expanded Scale Voltmeter stopwatch add am meter few resistors start investi gating Most ESYs draw about 250ma can see much yours draws putting am meter battery leads Now want test higher current need shunt across ESV power resistor 20 ohm resistor rated 2 watts put across ESV terminals will draw another 250ma approximately flight pack ammeter will show exactiy much current drawn Now actually perform test have suggested will find doubling dis charge current does cut discharge time half always get less half time Continued page 103 May1981 23 FliteCycle circuit board finished itemcompared quarter reference few will available mid-igal Contact UST Systems Suite 200 555 Broadhollow Rd Melville NY 11747 interested participating its development lump line between Ace RC NI-CD pack LR Taylor Super Power Panel isa simple 10 ohm 10 watt resistor wired across set Deans connectors connector reversed accommodate different wiring schemes battery pack power panels ESV resistor place ESV reads slightly less 47 VDC Removing resistor jumpathe voltage readingto485 VDC inthis particularcase maycalculatethatthe battery packs resistance state charge approximately 1/3 ohm ft 3/1 6-in flat rubber 100 ft I0-lb-test fishing line old antenna ribbon streamer place usual parachute optional tow hook shown plan worked very well yeilded better results desert hand-launching am sure would better twice length rubber line Maybe am just lazy Slope Soaring much liking especially late lazy afternoons wind down whisper just few Gliders left slopejust barely scratching out flight Zephyr really shines always last plane forced land can tossed up 50 ft above ridge just gentlest breezes will permit several passes problem very well yielded better results desert because youre still flying cant stay out brush down slope ridge Balance very important gentle forgiving little bird slow flight hand-launching speed range quite broad hand-launching easily going 50 mph launch leaves hand about 10 mph light lift can trimmed both conditions Thought would never ask get balance correct place will trimmed both conditions anything between throw up should go straight rock zooms up have too nose-heavy thats right nose-heavy too tail-heavy will tend arc downward slight dive both cases assumes have model adjusted relatively slow hands-off glide Without getting lengthy aerodynamic discussion extra nose weight causes extra up-elevator trim just keep model level during slow flight throw hard above trim speed up-elevator trim causes nose pull up can also test same thing gliding higher up Start slow-trimmed glide Gradually push nose down hold control stick same position model builds up speed tends pull out dive too nose-heavy dive steepens tail-heavy correct balance should continue same diving attitude started correct balance point Zephyr will loops rolls inverted flight dont expect inverted flight undercambered airfoil good upright flight decent wind slope should able maintain altitude inverted have Zephyr mastered make control surfaces sensitive travel better real fun Radio Technique/Myers Continued page 23 reason judge end-of-charge point voltage small part battery voltage lost across ammeter larger part lost inside battery batteries have internal resistance new AA-size nickle-cadmium battery will show about 035 ohms operating about 75% full charge As charge exhausted resistance increases until reaches about 100 ohms battery shows terminal voltage around 10 VDC numbers look small until consider multiply four get pack resistance add some ohms account welded tabs soldered joints wire plug Figure flight pack will vary depending its state charge Multiply resistance current Continued page 106 May1981 103 Shes surprisingly easy handle. can really get up go. WING SPAN 56 rfster LENGTH 39 WEIGHT 5-6 LBS POWER 40 C0VERITE 420 BABYLON RD 1-IORSHAM PA 19044 1YEAR WARRANTY WARRANTY OR SERVICE-K WORK CAR RE DONE UT RUQOR Hf 0 OR RY YOUR** REAREST ECIIO-KIORITZ PRODUCTS DEALERK** K** Exhaust Manifold Velocity Stack Kits Available * being drawn find out much voltage lost inside battery Volts x Ohms eq 4 Lets say during flight enough servos move against enough load draw 1 amp Lets also say battery partially discharged showing us 50 volts internal resis tance lost voltage will volt drops terminal voltage 4875 VDC No problem Now move over other end curve battery showing 47 VDC resistance has risen Ys ohm Lost voltage now 375 VDC terminal voltage drops 43 25 VDC consider 44 VDC end useful charge analysis tells us battery done day Suppose test ESY draws nominal 250ma voltage lost 047 VDC improper test shows 465 VDC ESV figure fine shape another flight think get point want compare Apples Apples instead Apples Oranges need shunt ESV enough external resistance make measure situation face flying larger servos Id permanently mount 10 ohm 10 watt resistor across plug THE RISING STAR IN GIANT SCALE ENGINES 24 CU inch 32 HP 8000 RPM 6/s lbs 03 Ring Piston Ball Bearings Crank Sealed Points VAYSHPPNG ON PRE-PAID ORDER * * Dealer Inquiries * * Welcome KK ROUSH MFG P0 Box 251 Sandyville OH 44671 Ph 216/866-9462 216/484-4374 see sketch ESV used test system powers three World Engines S-16 servos youre using something else now know figure similar shunt needs Lest ye think Im picking World Engines let point out real message column follows time decide something out ordinary consider consequences Some pretty subtle ESV have learned love trust designed around different situation face fly anything four ordinary servos number larger-than-ordinary ser vos Ive shown estimate average working current compensate ESV Ive also shown larger servos need larger batteries figure what need ratings came returned Christmas vacation 10 letters waiting responded request rating previous columns took rankings provided put point scores columns reverse order preference respondent listed five columns assigned five points most-liked column point least 10 columns mentioned top column got 10 points etc Based limited sampling top column 1980 September 80 column MEN C50/4 charger barely nosed out three columns Ace Silver Seven transmitter Third place went WRAMS show coverage didnt expect Five letters asked information Dual Mixer 10 letters expressed preference technical content scoring system biased favor people rated large number columns Doing statistics differently tried assigning scores order preference summing scores dividing number entries against item Using method lowest score greater zero best Dual Mixer column October 80 walked away rest MEN column came second Any way look respondents liked scientific articles show interest something unusual Most seemed want details Whats preference dont vote no will know Keep letters flowing George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 Letteri ng/Woaver Continued page 24 type used commercial art trade setting headlines available hundreds styles sizes Directions using press type explained catalogs put out various manufacturers Zip-A-Tone Formatt Letraset short simply draw straight line sheet paper position appropriate letters numbers line rub area stylus such pencil ball-point pen etc Remove plastic sheet Presto. beautiful master Use master make Xerox copies youre ready proceed illustrated steps way press type can used directly model Some care must exercised rub too hard ruin surface model After application number press type must fuel-proofed Light coats sprayed-on clear dope new fuel-proofing clear finishes will work long lightly apply first few coats SAFE FLYING IS NO ACCIDENT Features r Specifications s=-r ftfl~Span 86 II 1P111k i1I ITI'1 11111k IIgArea 1245sq-. IIIWeight 12 Engine 91 Cline drive unit elevators vertical fin rudder 1 Seperate detachable presheeted wing panels 2 Preassembiled fuselage frame 3 Preassembiled stabilizer IOC L 4 Epoxy Glass cowl wheelpants 5 Formed hatch clear canopy 6 Aluminum landing gear DEALER & 015 AWL OA INQUIRIES E Fronton St Brownsv lie TX 7852015121 5413867J Wayne Ulerys outstanding design Leo Loudenslagers Laser 200 geared 90 offered Model Merchant nearly constructed model critical fuselage & control surfaces framing wing sheeting has done Just some finish up ready fly best available 106 Model Aviation
Edition: Model Aviation - 1981/05
Page Numbers: 22, 23, 103, 106
echniquc EVERYONE wants use cheapest lightat battery pack possible So figure what size pack choose classical method invented rubber-motor experts know drill wind til breaksthen back off turn two counterpart RC guy uses what has until crash buys next larger size replace Its exciting way separate good stuff trash little hard model mathematician knows have multiply average operating current desired operating time find necessaty battery capacity problem finding out AMPS 3 IOLE 0 what average operating current typical RC situation operating system consists 500maH battery pack receiver switch harness four servos same type cases receiver idles about 2Oma servos idle 5 15 ma run free about 120ma stall 450ma observe combination can flown about two hours using 40- 60powered model hacking around usual sport-flying way hook stopwatch transmitter can keep track ON time use battery tester find out whats left battery return home learn average operating current situation about 260ma Now know operating current can vary idle stall current servo multiplied number servos use also know servos spend least much time idle doing work work depends loads servo must over come important point no servo can draw less idle current So its obvious operating current made up two compo nents idle currentwhich constant drain easy calculate working currentwhich extremely vari able hard calculate Schematic ESV-shunt make match characteristics system use three big servos regular onelike Quarter Scale job instance Operating Current Idle Current ing Currenteq 1 Going back paragraph estimate average operating current keeping few records dumping rest charge battery tester soon discover something like Average operating current a Idle current receiver plus 4 x iSma servos 8Oma mfrs data measure Therefore average working current 260- 80 l8Oma Which peculiar coincidence turns Out 15 x free running current average servo Estimated Working Current FreeRunning Currenteq 2 past two columns have urging calculate size servo need rather following Crash Replace school design gave tools calculate what need evaluate manufacturers literature select effi cient servo purposes Now well assume have decided build larger model have average kind RC system have decided need use three World Engines S-16 servos Lets see long battery will last keep flying same way keep using SOOmaH battery pack caine system Sample Problem No 1 Replace 3 servos S-I 6s 1 Compute system idle current Receiver 20 1 regular servo 15 Three 5-16 @ 8ma 24 59ma 2 Estimate working current case would consider aileron elevator servos S-16 therefore working current 400 ma 3 Estimate Operating Current 59 659ma 4 Estimate Operating Time SOOmah 59ma hours 45 minutes can hear screams starting Obviously picked S-16s make point powerful servos need powerful batteries point would just valid KPS-20H Atlas Chevron Magnum etc get large packs what size buy first part question easy answer since manufacturers offer large packs show pictures Ace RC NI-CD pack contains batteries rated 12 AmpHr World Engines pack rated 16 Amp-Hr should aware fact RC systems generally use batteries rated capacity discharging C/2 rate What mean World Engines 16 Amp-Hr pack rated deliver 16 Amp-Hr discharged 8 Amps 12 Amp-Hr Ace NI-CD pack rated 6 Amp rate Use either above 22 Model Aviation George M Myers lVisra-vi11keouS CUCrr f-oc1e OJe-1nq CUt4-1 J- TlE Figuring battery capacity need know much current system draws long its used per flight could look battery drain over period time would look some thing like World Engines S-16 servo its 16 amp-hour battery pack Below erence equipment Kraft KPS-15 servo 500maH pack performance differences much larger physical sizes would lead expect George couldnt resist Radio Shack stopwatch saw itthe color matches customized Ace Silver Seven transmitter watch used assist record-keeping connection gathering data current consumption airborne system Its also natural Sailplane Pylon Racing contests problem Mounted position polarizer screen LCD readout crossed Georges polarized sunglasses cant read flying repositioning transmitter situation fly modified system usual way will operate usual two hours above discussion related general problem does gather data own spec fic problem ideal situation would measure current demand flight back described tool called PLC 5000 did just works too delicate just stick airplane fly time local experimenter has come up durable digital device Flite * Cycle serves same purpose show photo proto type just will see its expensive isnt production now may never because will have sell over $100 have working in-flight recorder myself thats expensive also friends working telemetry system uses NE5044 chip multiplex several channels information will expensive solution may show up construc tion article days Ive heard tales other types instrumentation nothing publish have something working want share let editor know about Academy means society promotion science case science Model Aeronautics Lacking specific instrumentation best com mon approach started column wit fly known mission freshly charged batteries dump rest charge battery tester Compute average operating current subtracting dumped charge full charge dividing result mission time example might take off 100 loops land record elapsed time change battery packs next flight might 100 snap-rolls Change batteries agaln go back forth over field 100 times constant altitude Change batteries again make 100 circles convenient dia meter constant altitude Now go home discharge packs data will able estimate energy required straightand-level flight turns loops rolls data can estimate energy required mission have mind formula Average Operating Current x Operating Time ery Capacityeq 3 Figuring out what want half battle Measuring what youve got other half will find battery testers market draw about 250ma discharging battery packs value set analysis above Its pretty good flight packs little fast transmitter packs Transmit ters usually draw constant 1 3Oma Transmit ter current doesnt change significant amount move sticks would accurate discharge trans mitter packs 1 3Oma did youd wait four hours transmitter test two hours flight pack test Battery tester design ers figure its less confusing have both packs take about same time test So everyone gets used idea new battery pack tests 120 minutes time gets shorter pack gets older start drawing much larger currents test really begins lie As example could take ESV Expanded Scale Voltmeter stopwatch add am meter few resistors start investi gating Most ESYs draw about 250ma can see much yours draws putting am meter battery leads Now want test higher current need shunt across ESV power resistor 20 ohm resistor rated 2 watts put across ESV terminals will draw another 250ma approximately flight pack ammeter will show exactiy much current drawn Now actually perform test have suggested will find doubling dis charge current does cut discharge time half always get less half time Continued page 103 May1981 23 FliteCycle circuit board finished itemcompared quarter reference few will available mid-igal Contact UST Systems Suite 200 555 Broadhollow Rd Melville NY 11747 interested participating its development lump line between Ace RC NI-CD pack LR Taylor Super Power Panel isa simple 10 ohm 10 watt resistor wired across set Deans connectors connector reversed accommodate different wiring schemes battery pack power panels ESV resistor place ESV reads slightly less 47 VDC Removing resistor jumpathe voltage readingto485 VDC inthis particularcase maycalculatethatthe battery packs resistance state charge approximately 1/3 ohm ft 3/1 6-in flat rubber 100 ft I0-lb-test fishing line old antenna ribbon streamer place usual parachute optional tow hook shown plan worked very well yeilded better results desert hand-launching am sure would better twice length rubber line Maybe am just lazy Slope Soaring much liking especially late lazy afternoons wind down whisper just few Gliders left slopejust barely scratching out flight Zephyr really shines always last plane forced land can tossed up 50 ft above ridge just gentlest breezes will permit several passes problem very well yielded better results desert because youre still flying cant stay out brush down slope ridge Balance very important gentle forgiving little bird slow flight hand-launching speed range quite broad hand-launching easily going 50 mph launch leaves hand about 10 mph light lift can trimmed both conditions Thought would never ask get balance correct place will trimmed both conditions anything between throw up should go straight rock zooms up have too nose-heavy thats right nose-heavy too tail-heavy will tend arc downward slight dive both cases assumes have model adjusted relatively slow hands-off glide Without getting lengthy aerodynamic discussion extra nose weight causes extra up-elevator trim just keep model level during slow flight throw hard above trim speed up-elevator trim causes nose pull up can also test same thing gliding higher up Start slow-trimmed glide Gradually push nose down hold control stick same position model builds up speed tends pull out dive too nose-heavy dive steepens tail-heavy correct balance should continue same diving attitude started correct balance point Zephyr will loops rolls inverted flight dont expect inverted flight undercambered airfoil good upright flight decent wind slope should able maintain altitude inverted have Zephyr mastered make control surfaces sensitive travel better real fun Radio Technique/Myers Continued page 23 reason judge end-of-charge point voltage small part battery voltage lost across ammeter larger part lost inside battery batteries have internal resistance new AA-size nickle-cadmium battery will show about 035 ohms operating about 75% full charge As charge exhausted resistance increases until reaches about 100 ohms battery shows terminal voltage around 10 VDC numbers look small until consider multiply four get pack resistance add some ohms account welded tabs soldered joints wire plug Figure flight pack will vary depending its state charge Multiply resistance current Continued page 106 May1981 103 Shes surprisingly easy handle. can really get up go. WING SPAN 56 rfster LENGTH 39 WEIGHT 5-6 LBS POWER 40 C0VERITE 420 BABYLON RD 1-IORSHAM PA 19044 1YEAR WARRANTY WARRANTY OR SERVICE-K WORK CAR RE DONE UT RUQOR Hf 0 OR RY YOUR** REAREST ECIIO-KIORITZ PRODUCTS DEALERK** K** Exhaust Manifold Velocity Stack Kits Available * being drawn find out much voltage lost inside battery Volts x Ohms eq 4 Lets say during flight enough servos move against enough load draw 1 amp Lets also say battery partially discharged showing us 50 volts internal resis tance lost voltage will volt drops terminal voltage 4875 VDC No problem Now move over other end curve battery showing 47 VDC resistance has risen Ys ohm Lost voltage now 375 VDC terminal voltage drops 43 25 VDC consider 44 VDC end useful charge analysis tells us battery done day Suppose test ESY draws nominal 250ma voltage lost 047 VDC improper test shows 465 VDC ESV figure fine shape another flight think get point want compare Apples Apples instead Apples Oranges need shunt ESV enough external resistance make measure situation face flying larger servos Id permanently mount 10 ohm 10 watt resistor across plug THE RISING STAR IN GIANT SCALE ENGINES 24 CU inch 32 HP 8000 RPM 6/s lbs 03 Ring Piston Ball Bearings Crank Sealed Points VAYSHPPNG ON PRE-PAID ORDER * * Dealer Inquiries * * Welcome KK ROUSH MFG P0 Box 251 Sandyville OH 44671 Ph 216/866-9462 216/484-4374 see sketch ESV used test system powers three World Engines S-16 servos youre using something else now know figure similar shunt needs Lest ye think Im picking World Engines let point out real message column follows time decide something out ordinary consider consequences Some pretty subtle ESV have learned love trust designed around different situation face fly anything four ordinary servos number larger-than-ordinary ser vos Ive shown estimate average working current compensate ESV Ive also shown larger servos need larger batteries figure what need ratings came returned Christmas vacation 10 letters waiting responded request rating previous columns took rankings provided put point scores columns reverse order preference respondent listed five columns assigned five points most-liked column point least 10 columns mentioned top column got 10 points etc Based limited sampling top column 1980 September 80 column MEN C50/4 charger barely nosed out three columns Ace Silver Seven transmitter Third place went WRAMS show coverage didnt expect Five letters asked information Dual Mixer 10 letters expressed preference technical content scoring system biased favor people rated large number columns Doing statistics differently tried assigning scores order preference summing scores dividing number entries against item Using method lowest score greater zero best Dual Mixer column October 80 walked away rest MEN column came second Any way look respondents liked scientific articles show interest something unusual Most seemed want details Whats preference dont vote no will know Keep letters flowing George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 Letteri ng/Woaver Continued page 24 type used commercial art trade setting headlines available hundreds styles sizes Directions using press type explained catalogs put out various manufacturers Zip-A-Tone Formatt Letraset short simply draw straight line sheet paper position appropriate letters numbers line rub area stylus such pencil ball-point pen etc Remove plastic sheet Presto. beautiful master Use master make Xerox copies youre ready proceed illustrated steps way press type can used directly model Some care must exercised rub too hard ruin surface model After application number press type must fuel-proofed Light coats sprayed-on clear dope new fuel-proofing clear finishes will work long lightly apply first few coats SAFE FLYING IS NO ACCIDENT Features r Specifications s=-r ftfl~Span 86 II 1P111k i1I ITI'1 11111k IIgArea 1245sq-. IIIWeight 12 Engine 91 Cline drive unit elevators vertical fin rudder 1 Seperate detachable presheeted wing panels 2 Preassembiled fuselage frame 3 Preassembiled stabilizer IOC L 4 Epoxy Glass cowl wheelpants 5 Formed hatch clear canopy 6 Aluminum landing gear DEALER & 015 AWL OA INQUIRIES E Fronton St Brownsv lie TX 7852015121 5413867J Wayne Ulerys outstanding design Leo Loudenslagers Laser 200 geared 90 offered Model Merchant nearly constructed model critical fuselage & control surfaces framing wing sheeting has done Just some finish up ready fly best available 106 Model Aviation
Edition: Model Aviation - 1981/05
Page Numbers: 22, 23, 103, 106
echniquc EVERYONE wants use cheapest lightat battery pack possible So figure what size pack choose classical method invented rubber-motor experts know drill wind til breaksthen back off turn two counterpart RC guy uses what has until crash buys next larger size replace Its exciting way separate good stuff trash little hard model mathematician knows have multiply average operating current desired operating time find necessaty battery capacity problem finding out AMPS 3 IOLE 0 what average operating current typical RC situation operating system consists 500maH battery pack receiver switch harness four servos same type cases receiver idles about 2Oma servos idle 5 15 ma run free about 120ma stall 450ma observe combination can flown about two hours using 40- 60powered model hacking around usual sport-flying way hook stopwatch transmitter can keep track ON time use battery tester find out whats left battery return home learn average operating current situation about 260ma Now know operating current can vary idle stall current servo multiplied number servos use also know servos spend least much time idle doing work work depends loads servo must over come important point no servo can draw less idle current So its obvious operating current made up two compo nents idle currentwhich constant drain easy calculate working currentwhich extremely vari able hard calculate Schematic ESV-shunt make match characteristics system use three big servos regular onelike Quarter Scale job instance Operating Current Idle Current ing Currenteq 1 Going back paragraph estimate average operating current keeping few records dumping rest charge battery tester soon discover something like Average operating current a Idle current receiver plus 4 x iSma servos 8Oma mfrs data measure Therefore average working current 260- 80 l8Oma Which peculiar coincidence turns Out 15 x free running current average servo Estimated Working Current FreeRunning Currenteq 2 past two columns have urging calculate size servo need rather following Crash Replace school design gave tools calculate what need evaluate manufacturers literature select effi cient servo purposes Now well assume have decided build larger model have average kind RC system have decided need use three World Engines S-16 servos Lets see long battery will last keep flying same way keep using SOOmaH battery pack caine system Sample Problem No 1 Replace 3 servos S-I 6s 1 Compute system idle current Receiver 20 1 regular servo 15 Three 5-16 @ 8ma 24 59ma 2 Estimate working current case would consider aileron elevator servos S-16 therefore working current 400 ma 3 Estimate Operating Current 59 659ma 4 Estimate Operating Time SOOmah 59ma hours 45 minutes can hear screams starting Obviously picked S-16s make point powerful servos need powerful batteries point would just valid KPS-20H Atlas Chevron Magnum etc get large packs what size buy first part question easy answer since manufacturers offer large packs show pictures Ace RC NI-CD pack contains batteries rated 12 AmpHr World Engines pack rated 16 Amp-Hr should aware fact RC systems generally use batteries rated capacity discharging C/2 rate What mean World Engines 16 Amp-Hr pack rated deliver 16 Amp-Hr discharged 8 Amps 12 Amp-Hr Ace NI-CD pack rated 6 Amp rate Use either above 22 Model Aviation George M Myers lVisra-vi11keouS CUCrr f-oc1e OJe-1nq CUt4-1 J- TlE Figuring battery capacity need know much current system draws long its used per flight could look battery drain over period time would look some thing like World Engines S-16 servo its 16 amp-hour battery pack Below erence equipment Kraft KPS-15 servo 500maH pack performance differences much larger physical sizes would lead expect George couldnt resist Radio Shack stopwatch saw itthe color matches customized Ace Silver Seven transmitter watch used assist record-keeping connection gathering data current consumption airborne system Its also natural Sailplane Pylon Racing contests problem Mounted position polarizer screen LCD readout crossed Georges polarized sunglasses cant read flying repositioning transmitter situation fly modified system usual way will operate usual two hours above discussion related general problem does gather data own spec fic problem ideal situation would measure current demand flight back described tool called PLC 5000 did just works too delicate just stick airplane fly time local experimenter has come up durable digital device Flite * Cycle serves same purpose show photo proto type just will see its expensive isnt production now may never because will have sell over $100 have working in-flight recorder myself thats expensive also friends working telemetry system uses NE5044 chip multiplex several channels information will expensive solution may show up construc tion article days Ive heard tales other types instrumentation nothing publish have something working want share let editor know about Academy means society promotion science case science Model Aeronautics Lacking specific instrumentation best com mon approach started column wit fly known mission freshly charged batteries dump rest charge battery tester Compute average operating current subtracting dumped charge full charge dividing result mission time example might take off 100 loops land record elapsed time change battery packs next flight might 100 snap-rolls Change batteries agaln go back forth over field 100 times constant altitude Change batteries again make 100 circles convenient dia meter constant altitude Now go home discharge packs data will able estimate energy required straightand-level flight turns loops rolls data can estimate energy required mission have mind formula Average Operating Current x Operating Time ery Capacityeq 3 Figuring out what want half battle Measuring what youve got other half will find battery testers market draw about 250ma discharging battery packs value set analysis above Its pretty good flight packs little fast transmitter packs Transmit ters usually draw constant 1 3Oma Transmit ter current doesnt change significant amount move sticks would accurate discharge trans mitter packs 1 3Oma did youd wait four hours transmitter test two hours flight pack test Battery tester design ers figure its less confusing have both packs take about same time test So everyone gets used idea new battery pack tests 120 minutes time gets shorter pack gets older start drawing much larger currents test really begins lie As example could take ESV Expanded Scale Voltmeter stopwatch add am meter few resistors start investi gating Most ESYs draw about 250ma can see much yours draws putting am meter battery leads Now want test higher current need shunt across ESV power resistor 20 ohm resistor rated 2 watts put across ESV terminals will draw another 250ma approximately flight pack ammeter will show exactiy much current drawn Now actually perform test have suggested will find doubling dis charge current does cut discharge time half always get less half time Continued page 103 May1981 23 FliteCycle circuit board finished itemcompared quarter reference few will available mid-igal Contact UST Systems Suite 200 555 Broadhollow Rd Melville NY 11747 interested participating its development lump line between Ace RC NI-CD pack LR Taylor Super Power Panel isa simple 10 ohm 10 watt resistor wired across set Deans connectors connector reversed accommodate different wiring schemes battery pack power panels ESV resistor place ESV reads slightly less 47 VDC Removing resistor jumpathe voltage readingto485 VDC inthis particularcase maycalculatethatthe battery packs resistance state charge approximately 1/3 ohm ft 3/1 6-in flat rubber 100 ft I0-lb-test fishing line old antenna ribbon streamer place usual parachute optional tow hook shown plan worked very well yeilded better results desert hand-launching am sure would better twice length rubber line Maybe am just lazy Slope Soaring much liking especially late lazy afternoons wind down whisper just few Gliders left slopejust barely scratching out flight Zephyr really shines always last plane forced land can tossed up 50 ft above ridge just gentlest breezes will permit several passes problem very well yielded better results desert because youre still flying cant stay out brush down slope ridge Balance very important gentle forgiving little bird slow flight hand-launching speed range quite broad hand-launching easily going 50 mph launch leaves hand about 10 mph light lift can trimmed both conditions Thought would never ask get balance correct place will trimmed both conditions anything between throw up should go straight rock zooms up have too nose-heavy thats right nose-heavy too tail-heavy will tend arc downward slight dive both cases assumes have model adjusted relatively slow hands-off glide Without getting lengthy aerodynamic discussion extra nose weight causes extra up-elevator trim just keep model level during slow flight throw hard above trim speed up-elevator trim causes nose pull up can also test same thing gliding higher up Start slow-trimmed glide Gradually push nose down hold control stick same position model builds up speed tends pull out dive too nose-heavy dive steepens tail-heavy correct balance should continue same diving attitude started correct balance point Zephyr will loops rolls inverted flight dont expect inverted flight undercambered airfoil good upright flight decent wind slope should able maintain altitude inverted have Zephyr mastered make control surfaces sensitive travel better real fun Radio Technique/Myers Continued page 23 reason judge end-of-charge point voltage small part battery voltage lost across ammeter larger part lost inside battery batteries have internal resistance new AA-size nickle-cadmium battery will show about 035 ohms operating about 75% full charge As charge exhausted resistance increases until reaches about 100 ohms battery shows terminal voltage around 10 VDC numbers look small until consider multiply four get pack resistance add some ohms account welded tabs soldered joints wire plug Figure flight pack will vary depending its state charge Multiply resistance current Continued page 106 May1981 103 Shes surprisingly easy handle. can really get up go. WING SPAN 56 rfster LENGTH 39 WEIGHT 5-6 LBS POWER 40 C0VERITE 420 BABYLON RD 1-IORSHAM PA 19044 1YEAR WARRANTY WARRANTY OR SERVICE-K WORK CAR RE DONE UT RUQOR Hf 0 OR RY YOUR** REAREST ECIIO-KIORITZ PRODUCTS DEALERK** K** Exhaust Manifold Velocity Stack Kits Available * being drawn find out much voltage lost inside battery Volts x Ohms eq 4 Lets say during flight enough servos move against enough load draw 1 amp Lets also say battery partially discharged showing us 50 volts internal resis tance lost voltage will volt drops terminal voltage 4875 VDC No problem Now move over other end curve battery showing 47 VDC resistance has risen Ys ohm Lost voltage now 375 VDC terminal voltage drops 43 25 VDC consider 44 VDC end useful charge analysis tells us battery done day Suppose test ESY draws nominal 250ma voltage lost 047 VDC improper test shows 465 VDC ESV figure fine shape another flight think get point want compare Apples Apples instead Apples Oranges need shunt ESV enough external resistance make measure situation face flying larger servos Id permanently mount 10 ohm 10 watt resistor across plug THE RISING STAR IN GIANT SCALE ENGINES 24 CU inch 32 HP 8000 RPM 6/s lbs 03 Ring Piston Ball Bearings Crank Sealed Points VAYSHPPNG ON PRE-PAID ORDER * * Dealer Inquiries * * Welcome KK ROUSH MFG P0 Box 251 Sandyville OH 44671 Ph 216/866-9462 216/484-4374 see sketch ESV used test system powers three World Engines S-16 servos youre using something else now know figure similar shunt needs Lest ye think Im picking World Engines let point out real message column follows time decide something out ordinary consider consequences Some pretty subtle ESV have learned love trust designed around different situation face fly anything four ordinary servos number larger-than-ordinary ser vos Ive shown estimate average working current compensate ESV Ive also shown larger servos need larger batteries figure what need ratings came returned Christmas vacation 10 letters waiting responded request rating previous columns took rankings provided put point scores columns reverse order preference respondent listed five columns assigned five points most-liked column point least 10 columns mentioned top column got 10 points etc Based limited sampling top column 1980 September 80 column MEN C50/4 charger barely nosed out three columns Ace Silver Seven transmitter Third place went WRAMS show coverage didnt expect Five letters asked information Dual Mixer 10 letters expressed preference technical content scoring system biased favor people rated large number columns Doing statistics differently tried assigning scores order preference summing scores dividing number entries against item Using method lowest score greater zero best Dual Mixer column October 80 walked away rest MEN column came second Any way look respondents liked scientific articles show interest something unusual Most seemed want details Whats preference dont vote no will know Keep letters flowing George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 Letteri ng/Woaver Continued page 24 type used commercial art trade setting headlines available hundreds styles sizes Directions using press type explained catalogs put out various manufacturers Zip-A-Tone Formatt Letraset short simply draw straight line sheet paper position appropriate letters numbers line rub area stylus such pencil ball-point pen etc Remove plastic sheet Presto. beautiful master Use master make Xerox copies youre ready proceed illustrated steps way press type can used directly model Some care must exercised rub too hard ruin surface model After application number press type must fuel-proofed Light coats sprayed-on clear dope new fuel-proofing clear finishes will work long lightly apply first few coats SAFE FLYING IS NO ACCIDENT Features r Specifications s=-r ftfl~Span 86 II 1P111k i1I ITI'1 11111k IIgArea 1245sq-. IIIWeight 12 Engine 91 Cline drive unit elevators vertical fin rudder 1 Seperate detachable presheeted wing panels 2 Preassembiled fuselage frame 3 Preassembiled stabilizer IOC L 4 Epoxy Glass cowl wheelpants 5 Formed hatch clear canopy 6 Aluminum landing gear DEALER & 015 AWL OA INQUIRIES E Fronton St Brownsv lie TX 7852015121 5413867J Wayne Ulerys outstanding design Leo Loudenslagers Laser 200 geared 90 offered Model Merchant nearly constructed model critical fuselage & control surfaces framing wing sheeting has done Just some finish up ready fly best available 106 Model Aviation