MYERS Universal Gremlin-Finde point isAn RC system should draw idling current battery pack idle draws idle current battery charge will exhausted prematurely equipment will subjected unnecessary wear 0 First Questiov does find out what idling current should might begin manufacturers liter ature Idle currents usually specified either sales brochure Owners Handbook both Typically will find idle currents listed type servo receiver Make list equipment plane list idle current next item add up Fig 1 cant find data literature have Get hold back issues Flying Models magazine buddy Bob Aberle goes lot trouble put info review writes Bob has reviewed just about RC system Hes sort PGF Chinn RC crowd dont subscribe Try local library and/or flying buddies Still cant find out what blasted currents should Refer back Radio Technique ModelAviation August79 pp 22 etc Thats showed make ammeter adapter aileron extension cable Make will find useful pieces test equipment can make home See Fig 2 Install adapter between battery pack switch harness flight pack Connect VOM set range about 500 ma Turn receiver transmitter must off idle current should measure somewhere between 25 SO ma depending number servos manufacturer condition equipment Write what find meter some place owners manual should read something like Idle current 3 large servos 1 small a 7/4/79 some possibility error mea surement servos arent absolutely quiet make measurement current will read too high Jittery servos canbe caused other transmitters vicinity noisy servo group improper arrangement servo pigtails respect antenna metal clattering metal nearby Some older sets will go crazy simply jangle ring keys near receiver antenna transmitter turned off faced such problems have dispose before can get valid idle current measurement Second Question Now know what idle current should determine what Theres way find out sure need VOM adapter described above Turn receiver note idle current no-signal condition transmitter oIl turn transmitter meter should jump up momentarily settle back no-signal leveL Thats point little essay sake discussion lets assume current jumped up 300 ma stayed turned transmitter have trouble Turn off set unplug servos Turn transmitter receiver back agaln idle current receiver should between 10 50 ma Modem CMOS receivers par ticularly 2 4 channels tend group low end older 6- 8- channel sets draw high currents receiver draw ing 100 ma needs service Start plugging servos time observe jumps current servo should settle out about 10 25 ma above previous group Any servo increments current its brothers suspect find servo drawing exces sive current disconnect pushrod discon necting pushrod eliminates drain know item being controlled causing October 1979 21 Fig 1 typical list equipment specified idle currents summed up determine what no-signal drain flight pack battery should Fig 2 Myers Unviversal Gremlin Finder making connections meter solder lugs fastened large screws other pair solder lugs light bulbs inside meter supplied Fig 3 list properties measured used servos numbers will change slightly age use Stall current depends strongly motor stopped its commutator Toledo Show Gems Glenn Bussmans deHavilland Gypsy Moth Quadra powered weighs 18 lbs resulting 15-ounce wing loading Acrylic Aerogloss finish problem Some likely suspects 1 Throttle servo non-Perry throttles contain spring loads barrel closed direction Therefore continuously draw lot current wide-open throttle faced problem 1971 HP61 simply make new weaker spring Another problem area Low adjustment screw go low motor trim entirely possible servo ends up leaning screw Again draw excess current ammeter shows problem Check out situation see Im predicting problem never knew Incidentally throttle over-ride devices reduce eliminate excess current drain test plainly shows 2 Combined Nose-wheeVRudder Servo Everyone knows nose-wheel loads beat up servo its common practice put bend pushrod use spring device protect servo Unfortunately still have make sure nose-wheel tiller bar doesnt bottom out anywhere Left/Right range As throttle servo servo leans spring will use excess current 3 Landing Gear Refract mechanismsIt common practice use some form over center cam provide solid up-and downlock leaves load servo particularly fail use 1800 refract servo made especially service Anyone uses kind retract mechanism should perform idle current test both Up Down positions 4 Flaps Bomb Release Sailplane tow-hook release etcAny device might cam position have limited freedom motion should checked out position idle-current test 5 Rudder Elevator AileronsIf will slowly move control stick through its full range including trims stopping few de grees let things settle back idle current test will quickly show up epoxy hinges pushrods binding structure way control surfaces other little gremlins infest incompletely finished job fact such universal test wouldnt surprise bit see someone offer cheap ammeter kit line accessories youve got have someone does think theyll credit source Well see final thought help analyze problems Any servo has three different charac teristic currents according what doing Idle About lOmAenergized stationary no signal Free 150-250mArunning no mechanism connected Stalled about 450mAtrying push immovable object numbers will vary little manufac turer manufacturer among servo types much writing column measured bunch used servos tabulated results Fig 3 Use data example what expect shopping list Waming After use little gem may tempted build right airplane Dont meter too delicate stand up engine vibrations meter fails current flight pack lost Crash Keep letters coming folks havent done yet fill out send reader survey form printed page 8 August1979 issue Thanks George M Myers 70 Froehlich Farm R4 Hicksville NY 11801 22 Model Aviation Quarter-Scale Spad XIII SOS military entry Doug Dragoo Unusual power-plant M&M 14 cuin Doug used two servos ailerons photos Wischer Monster 11-foot span Fieseler Storch welded steel-tube fuselage work Glenn Buasman Quadra engine flies 285-lb plane true STOL performance
Edition: Model Aviation - 1979/10
Page Numbers: 21, 22
MYERS Universal Gremlin-Finde point isAn RC system should draw idling current battery pack idle draws idle current battery charge will exhausted prematurely equipment will subjected unnecessary wear 0 First Questiov does find out what idling current should might begin manufacturers liter ature Idle currents usually specified either sales brochure Owners Handbook both Typically will find idle currents listed type servo receiver Make list equipment plane list idle current next item add up Fig 1 cant find data literature have Get hold back issues Flying Models magazine buddy Bob Aberle goes lot trouble put info review writes Bob has reviewed just about RC system Hes sort PGF Chinn RC crowd dont subscribe Try local library and/or flying buddies Still cant find out what blasted currents should Refer back Radio Technique ModelAviation August79 pp 22 etc Thats showed make ammeter adapter aileron extension cable Make will find useful pieces test equipment can make home See Fig 2 Install adapter between battery pack switch harness flight pack Connect VOM set range about 500 ma Turn receiver transmitter must off idle current should measure somewhere between 25 SO ma depending number servos manufacturer condition equipment Write what find meter some place owners manual should read something like Idle current 3 large servos 1 small a 7/4/79 some possibility error mea surement servos arent absolutely quiet make measurement current will read too high Jittery servos canbe caused other transmitters vicinity noisy servo group improper arrangement servo pigtails respect antenna metal clattering metal nearby Some older sets will go crazy simply jangle ring keys near receiver antenna transmitter turned off faced such problems have dispose before can get valid idle current measurement Second Question Now know what idle current should determine what Theres way find out sure need VOM adapter described above Turn receiver note idle current no-signal condition transmitter oIl turn transmitter meter should jump up momentarily settle back no-signal leveL Thats point little essay sake discussion lets assume current jumped up 300 ma stayed turned transmitter have trouble Turn off set unplug servos Turn transmitter receiver back agaln idle current receiver should between 10 50 ma Modem CMOS receivers par ticularly 2 4 channels tend group low end older 6- 8- channel sets draw high currents receiver draw ing 100 ma needs service Start plugging servos time observe jumps current servo should settle out about 10 25 ma above previous group Any servo increments current its brothers suspect find servo drawing exces sive current disconnect pushrod discon necting pushrod eliminates drain know item being controlled causing October 1979 21 Fig 1 typical list equipment specified idle currents summed up determine what no-signal drain flight pack battery should Fig 2 Myers Unviversal Gremlin Finder making connections meter solder lugs fastened large screws other pair solder lugs light bulbs inside meter supplied Fig 3 list properties measured used servos numbers will change slightly age use Stall current depends strongly motor stopped its commutator Toledo Show Gems Glenn Bussmans deHavilland Gypsy Moth Quadra powered weighs 18 lbs resulting 15-ounce wing loading Acrylic Aerogloss finish problem Some likely suspects 1 Throttle servo non-Perry throttles contain spring loads barrel closed direction Therefore continuously draw lot current wide-open throttle faced problem 1971 HP61 simply make new weaker spring Another problem area Low adjustment screw go low motor trim entirely possible servo ends up leaning screw Again draw excess current ammeter shows problem Check out situation see Im predicting problem never knew Incidentally throttle over-ride devices reduce eliminate excess current drain test plainly shows 2 Combined Nose-wheeVRudder Servo Everyone knows nose-wheel loads beat up servo its common practice put bend pushrod use spring device protect servo Unfortunately still have make sure nose-wheel tiller bar doesnt bottom out anywhere Left/Right range As throttle servo servo leans spring will use excess current 3 Landing Gear Refract mechanismsIt common practice use some form over center cam provide solid up-and downlock leaves load servo particularly fail use 1800 refract servo made especially service Anyone uses kind retract mechanism should perform idle current test both Up Down positions 4 Flaps Bomb Release Sailplane tow-hook release etcAny device might cam position have limited freedom motion should checked out position idle-current test 5 Rudder Elevator AileronsIf will slowly move control stick through its full range including trims stopping few de grees let things settle back idle current test will quickly show up epoxy hinges pushrods binding structure way control surfaces other little gremlins infest incompletely finished job fact such universal test wouldnt surprise bit see someone offer cheap ammeter kit line accessories youve got have someone does think theyll credit source Well see final thought help analyze problems Any servo has three different charac teristic currents according what doing Idle About lOmAenergized stationary no signal Free 150-250mArunning no mechanism connected Stalled about 450mAtrying push immovable object numbers will vary little manufac turer manufacturer among servo types much writing column measured bunch used servos tabulated results Fig 3 Use data example what expect shopping list Waming After use little gem may tempted build right airplane Dont meter too delicate stand up engine vibrations meter fails current flight pack lost Crash Keep letters coming folks havent done yet fill out send reader survey form printed page 8 August1979 issue Thanks George M Myers 70 Froehlich Farm R4 Hicksville NY 11801 22 Model Aviation Quarter-Scale Spad XIII SOS military entry Doug Dragoo Unusual power-plant M&M 14 cuin Doug used two servos ailerons photos Wischer Monster 11-foot span Fieseler Storch welded steel-tube fuselage work Glenn Buasman Quadra engine flies 285-lb plane true STOL performance