THE LONGER write column 13 years counting get recurring questions Outside downwind turn common question probably figure out place center-of-gravity new plane obvious reason question keeps com ing new RC fliers enter hobby time theyve never read answer previ ous columns because joined since last ap peared Its time redo center-of-gravity calcula tion discussion hope hit happy medium tween boring excessive mathematics insulting intelligence Its difficult because background RC column read ers varied basic premise airfoil section has point about pitching moment constant point called aerodynamic center aerodynamic center center pressure may have heard about cen ter pressure point through re sultant force can assumed act order pro duce moment present Ive never liked center pressure concept never will will now go brief tirade dont like center pressure concept know lift pitching moment surface produces about point can divide pitching moment lift result distance point center pres sure sounds straightforward few hitches As angle attack surface changes both lift pitching moment change Unfortunately dont change linear ly get different answer time di vide pitching moment lift other words center pressure moves carry discussion extreme lets look typical airfoil like Figure 1 adjust angle attack airfoil until no lift produced well discover still negative pitching moment nose down present Lets calculate center pressure divide pitching moment Iiftoops can divide zero cant lets suppose wing tiny angle attack produces tiny amount lift pitch ing moment wont have changed much its still negative division pitching mo ment lift get very large negative num ber distance center pressure lo cates point thats contained airfoils surface dont like center pres sure concept End tirade -0-c Figure 1 Typical airfoil section Aerodynamic center noted sc T -L B Figure 2 Definition terms discussing aerodynamic surface Refer column l.C C6 X C0 0C L 193 iO7 CG 3 ILa u-J T toO Figure 4 Top view typical Pattern model Its used example text months discussion model aerodynamics Subject put center-of-gravity aerodynamic center does remain same point surface moves small distance large range angles attack airspeeds like aerodynamic center concept Theoretical aerodynamicists have determined aerodynamic center airfoils like ones use located point 25% local surface chord aft leading edge airfoil Figure 1 have aerodynamic surface wing tail looks like Figure 2 airfoil section will have its aerodynamic center point 25% local chord aft airfoil leading edge thin strip width dy length consti tuting local chord C incremental area wing fact C times dy incre 42 Model Aviation Radio Conoi Sport Aerobatics Ron Van Putte Ill Sleepy Oaks Rd Ft Walton Beach FL 32549 Figure 3 Side view typical Pattern modei Center-of-gravity cg mental area dont want frighten anyone away use integral calculus determine total wing area 5 get Equation 1 B12 1S cdy B/2R 8/2 Similarly can locate aerodynamic cen ter wing Figure 2 Equation 2 distance X distance between leading edge center wing aerody namic center 5/ 2 2XXcdy 8/2 R2 T2 RT R D/3) RT result mathematical hocus pocus equation can use determine aerodynamic center wings look like ones us use can also use same equation locate aerody namic center horizontal tail using ap propriate dimensions tail Suppose weve determined wing hori zontal tail areas using Equation 1 twice have located aerodynamic centers wing horizontal tail using Equation 2 twice Put side view airplane Figure 3 Equation 3 will locate proper CG R T second part equation values wing 3CGLxStab Area 3 x Wing Area R2 T2 T Lets try example Figure 4 shows typical airplane swept wing tail leading edges First calculate wing area using Equation 1 its 600 sq Next calculate tail area its 125 sq Now must calculate location wing aerodynamic center using Equation 2 swer 393 Note distance mea sured leading edge chord center wing location horizontal tail aerodynamic center 173 aft lead ing edge center horizontal tail Now can determine location center-of-gravity using Equation 3 yields 107 means proper center-of-gravity location 107 behind wing aerodynamic center exactly five inches behind leading edge wing hope try calculations sure understand use equa tions An airplane center-of-gravity calcu lated equations guaranteed stable pitch However after airplane flown may desirable move center-of-gravity back small amount make airplane re sponsive pitch reduce amount ele vator input required rolling maneuvers careful movement center-of-gravity get too far back alrplane will handful know some would like com plete discussion equations Ive shown developed So put together report Id happy send anyone sends SASE Next month Ill tell you can use equations Ive shown delta wing canard tail first airplanes received letter RJ Jim Pinkerton Continued page 134 Hundreds unusual tools bonowed Jewelry UGunsmithing Clock Making professional Iluel Makina trades NOW AVAILABLE TO YOU BY MAIL guaranteed I Use coupon send name anaress ann iuu MICRO MARK 541 Snyder Ave eley Heights NJ 07922 INAME ADDRESS L mii July 1988 43 Over 1000 TOOlS NEW Catalog FROM MicroMark Small Tool Specialists Curtiss Jenny * Quality hand-cut kit complete plans rigging scale control setup wire parts pre-bent special hardware included parts individually indentified packaged Decals Major Decal * Engine sizes 20 40 FS 25 TS * Wing unit removes four screws less 3 minutes flying wires left intact * Superb flight characteristics Introductory Price 12500 VISA erCard y Order Michigan residents add 4% sales tax Add $550 P&H US orders $1250 foreign Video Catalog $1250 Ipoat mci VHS/Beta 95 rebate return tape kit order Reg catalog sample mini-plan -$2 Hand-Cut Quality Affordable Price AERODROME MODELS LTD 2623 S Miller Rd 27Y__Saginaw MI 48603 517 781-3000 Other Kits Available Aero-Pacer Baby -Pacer Gipsy Moth Flybaby Flybaby Combo Hawker Hurricane Jester Table 2 PERFORMANCE SUMMARY SIX ASTRO COBALT iSa data average six motors RPM Voltage Current Power Mm/Max Psvr voltsampswattswatts 900077846461/68 tO000871028885/91 ItOCO98123119113/127 12000109146156150/168 13000120173204t97/220 ance spread relatively narrow included averages can also tell voltages currents super ferrites right line cobalt averages listing should useful would like know 15 cobalt super ferrite stacks up need run motor measure brush terminal volt age current prop rpmor two parametersand youll know yours com pares speed control installation easy range numbers may compared Fi nally seriously interested modelers can add versatility info smoothly graphing thereby having possible numbers range look As matter historic technical interest operating conditions voltage current power eight Astro cobalts super fer rites virtually indistinguishable other far performance concerned motor No 9my very old black back 15 power inputs various rpm levels exactly like newer motors input voltages currents quite different nothing bad about Its just earlier days Electric brushes commutators couldnt take heat motors wound operate higher voltages lower currents Thus good ol 15 normally used 16 cells lower currents todays iSs nor mally used 12 cells higher currents Bat tery cost driven cell count cell size same flight performance can say newer motors use cheaper batteries So much discussion Later well take look some performance information iSs various other propsand geared ver sions well Meanwhile upwards 200 watts comfortable capability 15and especially cobalt 15 because its lighter weightis good size consideration larger power system special request goes out person New York think 1987 KRC Electric Fly spent entire weekend tripod-mounted video camera youre reading please get touch Please forward comments questions photos SASE please address given very top column Happy Quiet Landings Everyone RC Aerobatics/ Van Putte Continued page 43 wrote Some months ago assembled Ace R/C Digipace kit Having amateur radio operator over 40 years Ive assembled kits well having laid out etched several boards relating RTTY particular kit should avoided experienced builder Anyone interested Digipace would be-well advised pay $10 difference tween mail order kit assembled tested unit reasons saying thistoo include letter would like assemble kit have enclosed tip sheet Ive put together tip sheet available anyone SASE Write RJ Pinkerton 2500 ONeal Circle Birmingham AL 35226 tip sheet RC Slope Soaring/Triebes Continued page 45 F3F slope racing rules use pilot stands center 330ft course After launch pilot has 30 sec onds get plane course Ten laps timed winner round re ceives 1000 points yes its exactly like F3B Speed contest has minimum 5 maximum 10 rounds throw-out round Its very simple CD infinitely difficult competi tor Fast runs good weather range 50 60 seconds best performance North Sea Cup 454 seconds 22 mph winds wind direction 20 side Danish record 403 seconds 40 mph winds slopes Denmark Swe den mostly coastside cliffs some 110 200 ft high 450 steep very clean have same type slopes southwest coast Norway also use inland mountains 4000 ft high night last summer flew F3B model hour two such slope Norway together 22 Norwegian Swedish pilotsno midairs typical Danish slope racer has twistwing ailerons flaps coupled elevator no brakes Wingspans average eight 81/2 ft use modified Eppler 180 374 airfoils E374 thinned 85% 10% reflex top E180 ten flattened popular airfoil used Den mark Thy Combination E180 root E374 tips thinned 10% Turn ing techniques less ballast name Speed game race highest winds loading 13 15 oz/sq ft unballasted 18 20 ozIsq ft bal lasted FUN what about Most magazines print technical organiza tional details slope gliding Northern Europe little said about great fun have must way share enjoyment sport certainly agree what Purben say ing whole reason us volved sport pure fun thrill want column dry technical report although will defi nitely contain some technical material rather means slope fliers around country world communicate ideas stories am really looking forward Slopers out send ing stories humorous exciting ser ious otherwise photos can shared other Slopers 134 Model Aviation Wa SUNSHINE HOBBY READY TO FLY Call 1-800-45-TO FLY ACCESSORIES INCLUDED PIPER CHEROKEE-40$12999 PIPER CHEROKEE-2510899 FOKKER E111-4011999 FANCY STICK-4tJ11499 FANCY STICK-256999 CESSNA 172-2010899 CONDOR-40L11999 TERCEL-4512199 ENGINE NOT INCLUDED PIONEER CAR$6000 ENGINE INCLUDED 17221 South Western Avenue Gardena California 90247 CONTACT us FOR THIS MONTHS 5PECIAL
Edition: Model Aviation - 1988/07
Page Numbers: 42, 43, 134
THE LONGER write column 13 years counting get recurring questions Outside downwind turn common question probably figure out place center-of-gravity new plane obvious reason question keeps com ing new RC fliers enter hobby time theyve never read answer previ ous columns because joined since last ap peared Its time redo center-of-gravity calcula tion discussion hope hit happy medium tween boring excessive mathematics insulting intelligence Its difficult because background RC column read ers varied basic premise airfoil section has point about pitching moment constant point called aerodynamic center aerodynamic center center pressure may have heard about cen ter pressure point through re sultant force can assumed act order pro duce moment present Ive never liked center pressure concept never will will now go brief tirade dont like center pressure concept know lift pitching moment surface produces about point can divide pitching moment lift result distance point center pres sure sounds straightforward few hitches As angle attack surface changes both lift pitching moment change Unfortunately dont change linear ly get different answer time di vide pitching moment lift other words center pressure moves carry discussion extreme lets look typical airfoil like Figure 1 adjust angle attack airfoil until no lift produced well discover still negative pitching moment nose down present Lets calculate center pressure divide pitching moment Iiftoops can divide zero cant lets suppose wing tiny angle attack produces tiny amount lift pitch ing moment wont have changed much its still negative division pitching mo ment lift get very large negative num ber distance center pressure lo cates point thats contained airfoils surface dont like center pres sure concept End tirade -0-c Figure 1 Typical airfoil section Aerodynamic center noted sc T -L B Figure 2 Definition terms discussing aerodynamic surface Refer column l.C C6 X C0 0C L 193 iO7 CG 3 ILa u-J T toO Figure 4 Top view typical Pattern model Its used example text months discussion model aerodynamics Subject put center-of-gravity aerodynamic center does remain same point surface moves small distance large range angles attack airspeeds like aerodynamic center concept Theoretical aerodynamicists have determined aerodynamic center airfoils like ones use located point 25% local surface chord aft leading edge airfoil Figure 1 have aerodynamic surface wing tail looks like Figure 2 airfoil section will have its aerodynamic center point 25% local chord aft airfoil leading edge thin strip width dy length consti tuting local chord C incremental area wing fact C times dy incre 42 Model Aviation Radio Conoi Sport Aerobatics Ron Van Putte Ill Sleepy Oaks Rd Ft Walton Beach FL 32549 Figure 3 Side view typical Pattern modei Center-of-gravity cg mental area dont want frighten anyone away use integral calculus determine total wing area 5 get Equation 1 B12 1S cdy B/2R 8/2 Similarly can locate aerodynamic cen ter wing Figure 2 Equation 2 distance X distance between leading edge center wing aerody namic center 5/ 2 2XXcdy 8/2 R2 T2 RT R D/3) RT result mathematical hocus pocus equation can use determine aerodynamic center wings look like ones us use can also use same equation locate aerody namic center horizontal tail using ap propriate dimensions tail Suppose weve determined wing hori zontal tail areas using Equation 1 twice have located aerodynamic centers wing horizontal tail using Equation 2 twice Put side view airplane Figure 3 Equation 3 will locate proper CG R T second part equation values wing 3CGLxStab Area 3 x Wing Area R2 T2 T Lets try example Figure 4 shows typical airplane swept wing tail leading edges First calculate wing area using Equation 1 its 600 sq Next calculate tail area its 125 sq Now must calculate location wing aerodynamic center using Equation 2 swer 393 Note distance mea sured leading edge chord center wing location horizontal tail aerodynamic center 173 aft lead ing edge center horizontal tail Now can determine location center-of-gravity using Equation 3 yields 107 means proper center-of-gravity location 107 behind wing aerodynamic center exactly five inches behind leading edge wing hope try calculations sure understand use equa tions An airplane center-of-gravity calcu lated equations guaranteed stable pitch However after airplane flown may desirable move center-of-gravity back small amount make airplane re sponsive pitch reduce amount ele vator input required rolling maneuvers careful movement center-of-gravity get too far back alrplane will handful know some would like com plete discussion equations Ive shown developed So put together report Id happy send anyone sends SASE Next month Ill tell you can use equations Ive shown delta wing canard tail first airplanes received letter RJ Jim Pinkerton Continued page 134 Hundreds unusual tools bonowed Jewelry UGunsmithing Clock Making professional Iluel Makina trades NOW AVAILABLE TO YOU BY MAIL guaranteed I Use coupon send name anaress ann iuu MICRO MARK 541 Snyder Ave eley Heights NJ 07922 INAME ADDRESS L mii July 1988 43 Over 1000 TOOlS NEW Catalog FROM MicroMark Small Tool Specialists Curtiss Jenny * Quality hand-cut kit complete plans rigging scale control setup wire parts pre-bent special hardware included parts individually indentified packaged Decals Major Decal * Engine sizes 20 40 FS 25 TS * Wing unit removes four screws less 3 minutes flying wires left intact * Superb flight characteristics Introductory Price 12500 VISA erCard y Order Michigan residents add 4% sales tax Add $550 P&H US orders $1250 foreign Video Catalog $1250 Ipoat mci VHS/Beta 95 rebate return tape kit order Reg catalog sample mini-plan -$2 Hand-Cut Quality Affordable Price AERODROME MODELS LTD 2623 S Miller Rd 27Y__Saginaw MI 48603 517 781-3000 Other Kits Available Aero-Pacer Baby -Pacer Gipsy Moth Flybaby Flybaby Combo Hawker Hurricane Jester Table 2 PERFORMANCE SUMMARY SIX ASTRO COBALT iSa data average six motors RPM Voltage Current Power Mm/Max Psvr voltsampswattswatts 900077846461/68 tO000871028885/91 ItOCO98123119113/127 12000109146156150/168 13000120173204t97/220 ance spread relatively narrow included averages can also tell voltages currents super ferrites right line cobalt averages listing should useful would like know 15 cobalt super ferrite stacks up need run motor measure brush terminal volt age current prop rpmor two parametersand youll know yours com pares speed control installation easy range numbers may compared Fi nally seriously interested modelers can add versatility info smoothly graphing thereby having possible numbers range look As matter historic technical interest operating conditions voltage current power eight Astro cobalts super fer rites virtually indistinguishable other far performance concerned motor No 9my very old black back 15 power inputs various rpm levels exactly like newer motors input voltages currents quite different nothing bad about Its just earlier days Electric brushes commutators couldnt take heat motors wound operate higher voltages lower currents Thus good ol 15 normally used 16 cells lower currents todays iSs nor mally used 12 cells higher currents Bat tery cost driven cell count cell size same flight performance can say newer motors use cheaper batteries So much discussion Later well take look some performance information iSs various other propsand geared ver sions well Meanwhile upwards 200 watts comfortable capability 15and especially cobalt 15 because its lighter weightis good size consideration larger power system special request goes out person New York think 1987 KRC Electric Fly spent entire weekend tripod-mounted video camera youre reading please get touch Please forward comments questions photos SASE please address given very top column Happy Quiet Landings Everyone RC Aerobatics/ Van Putte Continued page 43 wrote Some months ago assembled Ace R/C Digipace kit Having amateur radio operator over 40 years Ive assembled kits well having laid out etched several boards relating RTTY particular kit should avoided experienced builder Anyone interested Digipace would be-well advised pay $10 difference tween mail order kit assembled tested unit reasons saying thistoo include letter would like assemble kit have enclosed tip sheet Ive put together tip sheet available anyone SASE Write RJ Pinkerton 2500 ONeal Circle Birmingham AL 35226 tip sheet RC Slope Soaring/Triebes Continued page 45 F3F slope racing rules use pilot stands center 330ft course After launch pilot has 30 sec onds get plane course Ten laps timed winner round re ceives 1000 points yes its exactly like F3B Speed contest has minimum 5 maximum 10 rounds throw-out round Its very simple CD infinitely difficult competi tor Fast runs good weather range 50 60 seconds best performance North Sea Cup 454 seconds 22 mph winds wind direction 20 side Danish record 403 seconds 40 mph winds slopes Denmark Swe den mostly coastside cliffs some 110 200 ft high 450 steep very clean have same type slopes southwest coast Norway also use inland mountains 4000 ft high night last summer flew F3B model hour two such slope Norway together 22 Norwegian Swedish pilotsno midairs typical Danish slope racer has twistwing ailerons flaps coupled elevator no brakes Wingspans average eight 81/2 ft use modified Eppler 180 374 airfoils E374 thinned 85% 10% reflex top E180 ten flattened popular airfoil used Den mark Thy Combination E180 root E374 tips thinned 10% Turn ing techniques less ballast name Speed game race highest winds loading 13 15 oz/sq ft unballasted 18 20 ozIsq ft bal lasted FUN what about Most magazines print technical organiza tional details slope gliding Northern Europe little said about great fun have must way share enjoyment sport certainly agree what Purben say ing whole reason us volved sport pure fun thrill want column dry technical report although will defi nitely contain some technical material rather means slope fliers around country world communicate ideas stories am really looking forward Slopers out send ing stories humorous exciting ser ious otherwise photos can shared other Slopers 134 Model Aviation Wa SUNSHINE HOBBY READY TO FLY Call 1-800-45-TO FLY ACCESSORIES INCLUDED PIPER CHEROKEE-40$12999 PIPER CHEROKEE-2510899 FOKKER E111-4011999 FANCY STICK-4tJ11499 FANCY STICK-256999 CESSNA 172-2010899 CONDOR-40L11999 TERCEL-4512199 ENGINE NOT INCLUDED PIONEER CAR$6000 ENGINE INCLUDED 17221 South Western Avenue Gardena California 90247 CONTACT us FOR THIS MONTHS 5PECIAL
Edition: Model Aviation - 1988/07
Page Numbers: 42, 43, 134
THE LONGER write column 13 years counting get recurring questions Outside downwind turn common question probably figure out place center-of-gravity new plane obvious reason question keeps com ing new RC fliers enter hobby time theyve never read answer previ ous columns because joined since last ap peared Its time redo center-of-gravity calcula tion discussion hope hit happy medium tween boring excessive mathematics insulting intelligence Its difficult because background RC column read ers varied basic premise airfoil section has point about pitching moment constant point called aerodynamic center aerodynamic center center pressure may have heard about cen ter pressure point through re sultant force can assumed act order pro duce moment present Ive never liked center pressure concept never will will now go brief tirade dont like center pressure concept know lift pitching moment surface produces about point can divide pitching moment lift result distance point center pres sure sounds straightforward few hitches As angle attack surface changes both lift pitching moment change Unfortunately dont change linear ly get different answer time di vide pitching moment lift other words center pressure moves carry discussion extreme lets look typical airfoil like Figure 1 adjust angle attack airfoil until no lift produced well discover still negative pitching moment nose down present Lets calculate center pressure divide pitching moment Iiftoops can divide zero cant lets suppose wing tiny angle attack produces tiny amount lift pitch ing moment wont have changed much its still negative division pitching mo ment lift get very large negative num ber distance center pressure lo cates point thats contained airfoils surface dont like center pres sure concept End tirade -0-c Figure 1 Typical airfoil section Aerodynamic center noted sc T -L B Figure 2 Definition terms discussing aerodynamic surface Refer column l.C C6 X C0 0C L 193 iO7 CG 3 ILa u-J T toO Figure 4 Top view typical Pattern model Its used example text months discussion model aerodynamics Subject put center-of-gravity aerodynamic center does remain same point surface moves small distance large range angles attack airspeeds like aerodynamic center concept Theoretical aerodynamicists have determined aerodynamic center airfoils like ones use located point 25% local surface chord aft leading edge airfoil Figure 1 have aerodynamic surface wing tail looks like Figure 2 airfoil section will have its aerodynamic center point 25% local chord aft airfoil leading edge thin strip width dy length consti tuting local chord C incremental area wing fact C times dy incre 42 Model Aviation Radio Conoi Sport Aerobatics Ron Van Putte Ill Sleepy Oaks Rd Ft Walton Beach FL 32549 Figure 3 Side view typical Pattern modei Center-of-gravity cg mental area dont want frighten anyone away use integral calculus determine total wing area 5 get Equation 1 B12 1S cdy B/2R 8/2 Similarly can locate aerodynamic cen ter wing Figure 2 Equation 2 distance X distance between leading edge center wing aerody namic center 5/ 2 2XXcdy 8/2 R2 T2 RT R D/3) RT result mathematical hocus pocus equation can use determine aerodynamic center wings look like ones us use can also use same equation locate aerody namic center horizontal tail using ap propriate dimensions tail Suppose weve determined wing hori zontal tail areas using Equation 1 twice have located aerodynamic centers wing horizontal tail using Equation 2 twice Put side view airplane Figure 3 Equation 3 will locate proper CG R T second part equation values wing 3CGLxStab Area 3 x Wing Area R2 T2 T Lets try example Figure 4 shows typical airplane swept wing tail leading edges First calculate wing area using Equation 1 its 600 sq Next calculate tail area its 125 sq Now must calculate location wing aerodynamic center using Equation 2 swer 393 Note distance mea sured leading edge chord center wing location horizontal tail aerodynamic center 173 aft lead ing edge center horizontal tail Now can determine location center-of-gravity using Equation 3 yields 107 means proper center-of-gravity location 107 behind wing aerodynamic center exactly five inches behind leading edge wing hope try calculations sure understand use equa tions An airplane center-of-gravity calcu lated equations guaranteed stable pitch However after airplane flown may desirable move center-of-gravity back small amount make airplane re sponsive pitch reduce amount ele vator input required rolling maneuvers careful movement center-of-gravity get too far back alrplane will handful know some would like com plete discussion equations Ive shown developed So put together report Id happy send anyone sends SASE Next month Ill tell you can use equations Ive shown delta wing canard tail first airplanes received letter RJ Jim Pinkerton Continued page 134 Hundreds unusual tools bonowed Jewelry UGunsmithing Clock Making professional Iluel Makina trades NOW AVAILABLE TO YOU BY MAIL guaranteed I Use coupon send name anaress ann iuu MICRO MARK 541 Snyder Ave eley Heights NJ 07922 INAME ADDRESS L mii July 1988 43 Over 1000 TOOlS NEW Catalog FROM MicroMark Small Tool Specialists Curtiss Jenny * Quality hand-cut kit complete plans rigging scale control setup wire parts pre-bent special hardware included parts individually indentified packaged Decals Major Decal * Engine sizes 20 40 FS 25 TS * Wing unit removes four screws less 3 minutes flying wires left intact * Superb flight characteristics Introductory Price 12500 VISA erCard y Order Michigan residents add 4% sales tax Add $550 P&H US orders $1250 foreign Video Catalog $1250 Ipoat mci VHS/Beta 95 rebate return tape kit order Reg catalog sample mini-plan -$2 Hand-Cut Quality Affordable Price AERODROME MODELS LTD 2623 S Miller Rd 27Y__Saginaw MI 48603 517 781-3000 Other Kits Available Aero-Pacer Baby -Pacer Gipsy Moth Flybaby Flybaby Combo Hawker Hurricane Jester Table 2 PERFORMANCE SUMMARY SIX ASTRO COBALT iSa data average six motors RPM Voltage Current Power Mm/Max Psvr voltsampswattswatts 900077846461/68 tO000871028885/91 ItOCO98123119113/127 12000109146156150/168 13000120173204t97/220 ance spread relatively narrow included averages can also tell voltages currents super ferrites right line cobalt averages listing should useful would like know 15 cobalt super ferrite stacks up need run motor measure brush terminal volt age current prop rpmor two parametersand youll know yours com pares speed control installation easy range numbers may compared Fi nally seriously interested modelers can add versatility info smoothly graphing thereby having possible numbers range look As matter historic technical interest operating conditions voltage current power eight Astro cobalts super fer rites virtually indistinguishable other far performance concerned motor No 9my very old black back 15 power inputs various rpm levels exactly like newer motors input voltages currents quite different nothing bad about Its just earlier days Electric brushes commutators couldnt take heat motors wound operate higher voltages lower currents Thus good ol 15 normally used 16 cells lower currents todays iSs nor mally used 12 cells higher currents Bat tery cost driven cell count cell size same flight performance can say newer motors use cheaper batteries So much discussion Later well take look some performance information iSs various other propsand geared ver sions well Meanwhile upwards 200 watts comfortable capability 15and especially cobalt 15 because its lighter weightis good size consideration larger power system special request goes out person New York think 1987 KRC Electric Fly spent entire weekend tripod-mounted video camera youre reading please get touch Please forward comments questions photos SASE please address given very top column Happy Quiet Landings Everyone RC Aerobatics/ Van Putte Continued page 43 wrote Some months ago assembled Ace R/C Digipace kit Having amateur radio operator over 40 years Ive assembled kits well having laid out etched several boards relating RTTY particular kit should avoided experienced builder Anyone interested Digipace would be-well advised pay $10 difference tween mail order kit assembled tested unit reasons saying thistoo include letter would like assemble kit have enclosed tip sheet Ive put together tip sheet available anyone SASE Write RJ Pinkerton 2500 ONeal Circle Birmingham AL 35226 tip sheet RC Slope Soaring/Triebes Continued page 45 F3F slope racing rules use pilot stands center 330ft course After launch pilot has 30 sec onds get plane course Ten laps timed winner round re ceives 1000 points yes its exactly like F3B Speed contest has minimum 5 maximum 10 rounds throw-out round Its very simple CD infinitely difficult competi tor Fast runs good weather range 50 60 seconds best performance North Sea Cup 454 seconds 22 mph winds wind direction 20 side Danish record 403 seconds 40 mph winds slopes Denmark Swe den mostly coastside cliffs some 110 200 ft high 450 steep very clean have same type slopes southwest coast Norway also use inland mountains 4000 ft high night last summer flew F3B model hour two such slope Norway together 22 Norwegian Swedish pilotsno midairs typical Danish slope racer has twistwing ailerons flaps coupled elevator no brakes Wingspans average eight 81/2 ft use modified Eppler 180 374 airfoils E374 thinned 85% 10% reflex top E180 ten flattened popular airfoil used Den mark Thy Combination E180 root E374 tips thinned 10% Turn ing techniques less ballast name Speed game race highest winds loading 13 15 oz/sq ft unballasted 18 20 ozIsq ft bal lasted FUN what about Most magazines print technical organiza tional details slope gliding Northern Europe little said about great fun have must way share enjoyment sport certainly agree what Purben say ing whole reason us volved sport pure fun thrill want column dry technical report although will defi nitely contain some technical material rather means slope fliers around country world communicate ideas stories am really looking forward Slopers out send ing stories humorous exciting ser ious otherwise photos can shared other Slopers 134 Model Aviation Wa SUNSHINE HOBBY READY TO FLY Call 1-800-45-TO FLY ACCESSORIES INCLUDED PIPER CHEROKEE-40$12999 PIPER CHEROKEE-2510899 FOKKER E111-4011999 FANCY STICK-4tJ11499 FANCY STICK-256999 CESSNA 172-2010899 CONDOR-40L11999 TERCEL-4512199 ENGINE NOT INCLUDED PIONEER CAR$6000 ENGINE INCLUDED 17221 South Western Avenue Gardena California 90247 CONTACT us FOR THIS MONTHS 5PECIAL