Dihedral

NO OCR TEXT NO OCR TEXT Figure 1 five dihedral schemes have same Equivalent Dihedral Angle EDA 100 ThIs illustrates different dihedral schemes can have same rolling power order top called V Three-Panel Polyhedral Four-Panel Polyhedral Para bolic Inverted Gull table below details geometry of various schemes Dihedral Type V dihedral 3-panel 4-panel Parabolic Inverted Gull Inboard Angle degree 1000 000 Outboard Angle degree 1000 1961 435 Z 0296/spanX2* -1500 Panel Break spanl2 NA 06 1304 1407 Z height along wing semi-span station X Figure 2 Dihedral causes change angle attack wing yawed di agram apparent change roughly proportional dihedral angle D yaw angle ii Note change angle attack forward wing positive equal opposite change angle attack aft wing Total lift remains constant Figure 3 ThIs graphic illustration Figure 2 Imagine wings flying toward yawed right shaded underside wing presented wind planes left side same degree light upper surface presented right side difference angle attack will cause rolling moment planes right Note amount change angle attack increases local dihedral angle Dihedral mechanism job dihedral increase lift side plane decrease other air plane yawed does increasing angle attack forward wing decreasing aft wing As can see Figure 2 airstream passing over leading dihedraled wing leaves trailing edge lower hit lead ing edgean effective increase angle attack trailing wing opposite true effect also illustrated Figure 3 dark underside forward wing visible light upper surface aft wing proportion local dihedral angle little trigonometry applied Fig ure 2 following equation can de rived Moderate angles dihedral yaw angle attack assumed Also no 05 doubt air does exactly follow such NA nice neat lines purpose ap proximating effect dihedral rea 03 sonable assumption Change angle attack - ARCTAN SIN Yaw x TAN Dihedral angle Delta Alpha AN SIN 5 TAN D formula graphed Figure 4 Note change angle attack approx imately proportional both dihedral gle yaw angle change angle attack determines change lift based lift curve slope lift curve slope varies pect ratio degree wing section Remarkably though lift curve slope approximately constant within wings unstalled range angle attack sim plify analysis article assumes typical value 01 Cl per degree wings wing rolling moment can cal culated planform wing known constant-chord wing will gener ate rolling moment highly ta pered since has area outboard have chosen evaluate wings elliptical planform since wings approximate classic shape roll moment wing may esti mated dividing wing large num ber panels same way ribs di vide wing lift panel may computed based its chord angle tack airspeed product lift distance panel airplane cen terline roll moment produced panel sum of panel moments net moment airplane Since distance side airplane taken positive other side negative net moment symmetrical airplane straight flight zerothat does roll analysis article have divided wing 20 panels Since change angle attack roughly proportional dihedral angle yaw angle follows roll mo ment also approximately proportional 94 Model Aviation Local Dihedral Angie 30 III 11114 I I I 0510 aw Angle degrees 250 20 150 202530 og 08 07 06 Moment Fraction 04 03 02 01 0 ILI II IIt 0 01 02 03 04 05 06 07 08 og rootSemispan Stationtip Figure 4 left change angle attack Delta Alpha roughly proportional yaw angle local dihedral angle plot shows Delta Alpha six different dihedral angles over range yaw angles Figure 5 right Most roll force comes out board portion wing plot shows roll force fraction due portion wing outboard given wing semi-span station elliptical planform wing instance wing center station 0 wing outboard 100% roll moment produced outboard half wing station 05 out produces 65% total moment inboard half produces 35% Half roll moment comes wing outboard station 06 plot critical calculating Equivalent Dihedral Angle described text yaw dihedral example means doubling dihedral angle will yield twice roll moment Equivalent dihedral angle formal aerodynamics coefficient quantifies roll moment wing function wingspan area airspeed air density yaw angle coefficient called Clj3 see-el-beta dimensionless coefficient difficult lay modeler utilize have come up another term Equi valent Dihedral Angle EDA liffle easier visualize V-dihedral wing taken standard instance 10 0-per-side V-dihedral wing has EDA 100 Another type dihedral may quantified having equivalent dihedral angle though made up multiple angles Two wings have equal EDA generate same rolling moment suming equal wingspan area airspeed air density yaw angle Figure 1 illustrates five wings have same EDA despite different dihe dral schemes Note EDA has nothing span aspect ratio proportions angles dihedral ar rangement wing planform does have minor effectmore about later wing rolling moment sum moments generated small panel wing lifting distance cen terline airplane fraction tal wing moment wing outboard given semi-span station graphed Figure 5 graph reflects fact outboard portions wing have longer moment arm generate roll moment instance outboard half wing has less 40% area has 65% rolling moment moment fraction would greater except reduced chord near tip elliptical planform wing simple structure calculate EDA might three-panel wing flat center section tips bent up 100 panel break 05 semi-span Since cen ter section has no dihedral angle contrib utes nothing EDA outboard pan els generate 065 rolling moment 65% effective full V-dihe dral wing 100 dihedral Therefore three-panel wing has EDA 065 X 100 Now take four-panel wing 50 board 100 outboard again panel break 05 semi-span outboard panels same size angle previous example generate same EDA inboard panels generate remainder moment 10 035 35% effective dihedral wing 50 dihedral board panels yield EDA 035 X 50 175 0 sum panels yields total EDA 825 0 can compute EDA many-panel wing Take six-panel wing breaks 04 07 semi-span stance inner panel generates 1 022 moment center panel gener ates 078 041 moment tip panel generates 037 37 moment Continued page 166 Computing EDA Computing Equivalent Dihedral Angle straightforward based location dihedral breaks dihedral angle panel fraction full wing moment generated panel location panel break quanti fied terms fraction halfspan instance four-panel wing has its panel break halfway out tip panel break 05 semi-span dihedral angle panel sim ply the angle panel relative horizontal line neighboring panel Z7T7i Figure 6 Dihedral types have analogous aileron schemes Dihedral type determines roll power generated much same way aileron chord location anal ogy local dihedral angle related local aileron chord fraction useful under standing dihedral based understanding ailerons vice versa Some informa tion can applied aileron airplanes estimating power ailerons good rule thumb ailerons modest deflections higher Reynolds numbers about 02 chord 10 aileron deflection equals about 05 change angle attack chord August 1988 95 16 14 12 10 Delta Alpha degrees 8 6 4 2 0 48/ TS FUN-TO-FLY SPORTS AIRCRAFT SLOW AND STABLE WITH 25 ENGINE FOR TRAINING FAST AND FULLY AEROBATIC WITH 40 ENGINE SPECIFICATIONS WINGSPAN50 IN WING AREA500 50 IN LENGHT34 IN WEIGHT31/2 4 LBS ENGINE25 40 KIT FEATURES BUILT UP WING &FUSEL SELECT BALSA SPRUCE & LIGHT PLYWOOD ALL PARTS MACHINED & FITTED PHOTOILLUSTRATEDCONSTRUCTIONBOOK oCOMPLETE HARDWARE PACKAGE 5995 TERMS KITS IN STOCK FORCHECK MONEY JER IMMEDIATE DELIVERYOR COD CASH ADD$400 FOR SHIPPING DEALER INQUIRIESjj~ ... ADD$300 FORCOD INVITEDARIZONA RESIDENTS ADD 1109 SOUTH PLAZA WAY #335FLAGSTAFF AZ 860016% FOR SALES TAX true square up After light sanding cut opening cowl seal up well last finish coat resin inside out Finishing painting Give model final sanding 400-grit sandpaper before filling dents blending everything Model Magic Filler Apply coat K&B Finishing Resin followed sand ing 400-grit paper dry Add second light coat resin go over model again 400-grit sandpaper applied two coats gray NAPA auto lacquer primer dry lightly sanded 600-grit sandpaper Two coats glossy black Perfect Paint Cheveron sprayed rest trim paint decals added coat clear satin sprayed used Chev eron Perfect Paint exclusively its easi est forgiving paint likely encounter Flying first order business check model balances centerof-gravity shown plan better yet make airplane little nose-heavy Before connecting lines certain plane will roll straight forward outside circle adjustable nose gear comes handy operation good friend Indianapolis Steve Ashby gave helpful hand starting engines first flight started outboard engine leaned out started leaned out inboard en gine match outboard Boy let tell crowed inboard matched outboard pure magic ears What beauti ful hypnotic sound just stood like plant soaking up until Steve ask going merely stand planning fly know answer lieve fly did day P-61 has ter rific flier never letdown Its very sta ble smooth wind touch-andgo maneuvers great wing tank drops 19 engines provide model adequate power thing go something biggerdont go less Whether flown competition purely fun Black Widow has consistently winner modeler cant ask Dihedral/Beron-Rawdon Continued page 95 moment fractions panel simply multiplied panel dihedral gle summed find EDA Further examples provided Figure 1 have EDA 100 Analogy ailerons amount dihe dral wing panel has determines its roll power plane yawed Thus plane flat center panel center panel makes no contribution roll power tip panels everything ap proximately equivalent aileron wing partial-span barn door ailerons V-dihedral wing makes equal contribu tion delta alpha-wise along length wing analogous strip aile rons taper proportion wing chord other analogies illus trated Figure 6 Note analogies may turned around used better understand function ailerons instance can see Figure 4 05 semi-span barn door ailerons will about 65% power ful full-span strip ailerons same percentage chord Transitional maneuvers steadystate maneuvers such rolling circling managed very well rudder eleva tor airplanes transitional maneuvers such initiating ending roll maneuver weak point because double series events required initiate end maneuver example series events re quired transition rapidly straight flight steady-state turn fairly com plex large rudder deflection accelerates plane yaw axis As plane comes yawed begins accelerate roll axis As plane approaches maxi mum yaw angle rudder deflection se lected plane decelerates yaw until maximum yaw angle reached air plane underdamped yaw due heavy wing tips undersized rudder may overshoot steady-state maximum yaw angle oscillate briefly about maximum angle Shortly after plane reaches maximum yaw angle maximum roll rate achieved Rudder deflection held until desired bank angle ap proached rudder neutralized airplane yaws back zero yaw airplane stops rolling again delays acceleration deceleration As can see order plane roll first must yaw order stop rolling must stop yawing order min imize lag between control input re sponse yaw roll acceleration decel eration should maximized achieved large fin/rudder long tall moment arm generous dihedral light weight airplane extremities namely wing tips tail group extremities overweight vertical stabilizer undersized too short moment arm plane will difficult fly precisely Its response will slow start will tend coast past desired re sponse prompting control input op posite direction input may also overshot airplane will end up wal lowing around will force pilot very slow smooth control puts giving up potential rapid pre cise control dihedral angle insufficient larger yaw excursions will necessary gener ate desired roll response will make planes response sluggish will reduce maximum roll rate Conversely plane has ample dihe dral lightweight extremities long tail mo ment generous vertical stabilizer its handling can immediate precise powerful General comments some inter esting properties point out about beha vior dihedral given airplane roll moment generated function yaw angle airspeed noteworthy overall angle attack impor tant unless airplane nearly stalled speed yaw angle same 166 Model Aviation airplane will roll same direction same speed upright upside down 0-g dive true because roll moment generated equal opposite changes angle attack left wing right Within wings unstalled range angle tack change lift per change angle attack approximately constant cause change matters base angle attack important Note also because equal opposite change yawing airplane will cause change total lift gener ated nice feature able roll thermal having simultane ously compensate pitch However air planes high rates yaw roll possibility gyroscopic coupling yaw roll axes yielding unex pected pitch-up response due gyroscopic precession problem coordi nated aileron aircraft since axis being spun time Swept-wing arrangements couple yaw roll much like dihedral doesbut some important differences yawed swept wing generates roll moment differ ence effective length wings wings still produce roughly same amount lift since have same area roughly same angle attack wing longer other has leverage means roll moment swept wing related to tal lift being produced yaw angle plane yawed 1 g roll mo ment will same independent speed pulling three gravities roll moment will three times great 0-g dive no roll mo ment upside down 1 g roll moment reversed Radio Con trol pure swept-wing model dihe dral ailerons will very tricky air plane fly well swept-wing airplanes ailerons emphasis rudder coordina tion will prevent unexpected responses Summary conclusions dihedral arrangement crucial handling roll axis Dihedral provides coupling between yaw roll roughly proportional Equivalent Dihedral Angle EDA yaw angle rolling moment wing can com puted based its dihedral arrangement yaw angle airspeed wingspan wing area planform Different dihedral arrangements have same roll moment otherwise equal V-dihedral wing said have Equivalent Dihedral Angle equal dihedral angle V-dihedral wing Equivalent Dihedral Angle given dihedral arrangement may easily calcu lated Various dihedral arrangements have anal ogies aileron arrangements Transitional maneuvers weak point rudder-and-elevator airplanes Generous dihedral long tail moment arm large verti Step future AVIATION Become Aviation Electronics Technician learn repair maintain electronic equipment used aboard aircraft Actual planes used training Hangar runway campus Train just 19 months Jobs waiting CALL NOW 1-800-758-5757 CLOVER PARK Vocational Technical Institute 4500 Steilacoom Blvd SW Tacoma WA 98499-4098 FAA Repair Station #4466 cal stabilizer lightweight wing tip pan els tail group minimize transitional shortcomings roll moment dihedral wing dependent overall angle attack Swept wings behave quite differently dihedral wings RC Soaring/Blakeslee Continued page 54 Adjustable preset trims Launch Cruise Speed Simple switch-selection simplifies pilots work during critical launch sequences In-flight setup changing Switch planes config uration on-the-fly try Out new adjustments enhance performance during particular events Landing position flap threshold selection Al lows set trip-point triggers aile ron spoiler deployment Works Airtronics FM/PPM FM/PCM receivers Initially Module 7SP Other brands added deal contact CSL make reserva tion have transmitter converted will send shipping kit sending transmitter work takes about 10 days ATRCS-modified transmitter re turned users manual explains program using examples illustrations Dur ing setup sequence asked inputs through menu-style prompts Special program features arc designed help enter correct information prevent accidental loss set ups Full information available fmm CSL 1361 Fallen Leaf Dr Milpitas CA 95035 can call 408 946-4142 SM Sailplanes Vince Parizek produces limited number Sailplane mostly Scale kits Kits may best word describe since Vinces planes appear pretty completely fin ished Lets have Vince tell us about himself well get specs two big Scale Sallplanes Just let know about background have involved RC Gliders years have building own Gliders quite some time grew up Europe became interested Scale Glid ers Since arriving States 1968 found basically no Scale ships made concerned however because could purchased Germany past few years drop dollar has put price out reach average modeler So decided offer experience Scale enthusiasts reasonable prices Because still hobby make kit myself production low waiting list stands about four weeks SMs two Scale ships Start & Flug H101 Salto 44-meters wingspan fourmeter Schleicher AS-W 17 Both have white gel coat epoxy glass fuselages foam wings sheeted obechi wood wings have ply wood spars plus carbon fiber reinforcement Aile ron spoiler areas reinforced twoounce glass cloth Tail surfaces also obechi covered foam Individual specs Salto fuselage 67in long wing area 1140 sq weight 85 lb wing loading 16-18 oz per sq ft airfoil modified Ritz II AS-W 17 specs include fuselage 59-in long wing area 1020 sq weight seven pounds wing loading 14 oz per sq ft airfoil modified Ritz III Both planes available basic com plete kit explained easily listing what complete kit gives leading edges wing tips installed shaped precut aile rons spoilers installed precut plywood pieces radio installation set decals Salto complete kit includes wheel basic complete kits AS-W 17 $289 $385 respectively Salto kits $425 $515 full-size AS-W 17 has 20-meter span model / scale Seventeen has enormously popular subject modelers H101 Salto much rarer subject Its maker offshoot Glasfiugel factory first flew 1971 wings Standard August 1988 167

NO OCR TEXT NO OCR TEXT Figure 1 five dihedral schemes have same Equivalent Dihedral Angle EDA 100 ThIs illustrates different dihedral schemes can have same rolling power order top called V Three-Panel Polyhedral Four-Panel Polyhedral Para bolic Inverted Gull table below details geometry of various schemes Dihedral Type V dihedral 3-panel 4-panel Parabolic Inverted Gull Inboard Angle degree 1000 000 Outboard Angle degree 1000 1961 435 Z 0296/spanX2* -1500 Panel Break spanl2 NA 06 1304 1407 Z height along wing semi-span station X Figure 2 Dihedral causes change angle attack wing yawed di agram apparent change roughly proportional dihedral angle D yaw angle ii Note change angle attack forward wing positive equal opposite change angle attack aft wing Total lift remains constant Figure 3 ThIs graphic illustration Figure 2 Imagine wings flying toward yawed right shaded underside wing presented wind planes left side same degree light upper surface presented right side difference angle attack will cause rolling moment planes right Note amount change angle attack increases local dihedral angle Dihedral mechanism job dihedral increase lift side plane decrease other air plane yawed does increasing angle attack forward wing decreasing aft wing As can see Figure 2 airstream passing over leading dihedraled wing leaves trailing edge lower hit lead ing edgean effective increase angle attack trailing wing opposite true effect also illustrated Figure 3 dark underside forward wing visible light upper surface aft wing proportion local dihedral angle little trigonometry applied Fig ure 2 following equation can de rived Moderate angles dihedral yaw angle attack assumed Also no 05 doubt air does exactly follow such NA nice neat lines purpose ap proximating effect dihedral rea 03 sonable assumption Change angle attack - ARCTAN SIN Yaw x TAN Dihedral angle Delta Alpha AN SIN 5 TAN D formula graphed Figure 4 Note change angle attack approx imately proportional both dihedral gle yaw angle change angle attack determines change lift based lift curve slope lift curve slope varies pect ratio degree wing section Remarkably though lift curve slope approximately constant within wings unstalled range angle attack sim plify analysis article assumes typical value 01 Cl per degree wings wing rolling moment can cal culated planform wing known constant-chord wing will gener ate rolling moment highly ta pered since has area outboard have chosen evaluate wings elliptical planform since wings approximate classic shape roll moment wing may esti mated dividing wing large num ber panels same way ribs di vide wing lift panel may computed based its chord angle tack airspeed product lift distance panel airplane cen terline roll moment produced panel sum of panel moments net moment airplane Since distance side airplane taken positive other side negative net moment symmetrical airplane straight flight zerothat does roll analysis article have divided wing 20 panels Since change angle attack roughly proportional dihedral angle yaw angle follows roll mo ment also approximately proportional 94 Model Aviation Local Dihedral Angie 30 III 11114 I I I 0510 aw Angle degrees 250 20 150 202530 og 08 07 06 Moment Fraction 04 03 02 01 0 ILI II IIt 0 01 02 03 04 05 06 07 08 og rootSemispan Stationtip Figure 4 left change angle attack Delta Alpha roughly proportional yaw angle local dihedral angle plot shows Delta Alpha six different dihedral angles over range yaw angles Figure 5 right Most roll force comes out board portion wing plot shows roll force fraction due portion wing outboard given wing semi-span station elliptical planform wing instance wing center station 0 wing outboard 100% roll moment produced outboard half wing station 05 out produces 65% total moment inboard half produces 35% Half roll moment comes wing outboard station 06 plot critical calculating Equivalent Dihedral Angle described text yaw dihedral example means doubling dihedral angle will yield twice roll moment Equivalent dihedral angle formal aerodynamics coefficient quantifies roll moment wing function wingspan area airspeed air density yaw angle coefficient called Clj3 see-el-beta dimensionless coefficient difficult lay modeler utilize have come up another term Equi valent Dihedral Angle EDA liffle easier visualize V-dihedral wing taken standard instance 10 0-per-side V-dihedral wing has EDA 100 Another type dihedral may quantified having equivalent dihedral angle though made up multiple angles Two wings have equal EDA generate same rolling moment suming equal wingspan area airspeed air density yaw angle Figure 1 illustrates five wings have same EDA despite different dihe dral schemes Note EDA has nothing span aspect ratio proportions angles dihedral ar rangement wing planform does have minor effectmore about later wing rolling moment sum moments generated small panel wing lifting distance cen terline airplane fraction tal wing moment wing outboard given semi-span station graphed Figure 5 graph reflects fact outboard portions wing have longer moment arm generate roll moment instance outboard half wing has less 40% area has 65% rolling moment moment fraction would greater except reduced chord near tip elliptical planform wing simple structure calculate EDA might three-panel wing flat center section tips bent up 100 panel break 05 semi-span Since cen ter section has no dihedral angle contrib utes nothing EDA outboard pan els generate 065 rolling moment 65% effective full V-dihe dral wing 100 dihedral Therefore three-panel wing has EDA 065 X 100 Now take four-panel wing 50 board 100 outboard again panel break 05 semi-span outboard panels same size angle previous example generate same EDA inboard panels generate remainder moment 10 035 35% effective dihedral wing 50 dihedral board panels yield EDA 035 X 50 175 0 sum panels yields total EDA 825 0 can compute EDA many-panel wing Take six-panel wing breaks 04 07 semi-span stance inner panel generates 1 022 moment center panel gener ates 078 041 moment tip panel generates 037 37 moment Continued page 166 Computing EDA Computing Equivalent Dihedral Angle straightforward based location dihedral breaks dihedral angle panel fraction full wing moment generated panel location panel break quanti fied terms fraction halfspan instance four-panel wing has its panel break halfway out tip panel break 05 semi-span dihedral angle panel sim ply the angle panel relative horizontal line neighboring panel Z7T7i Figure 6 Dihedral types have analogous aileron schemes Dihedral type determines roll power generated much same way aileron chord location anal ogy local dihedral angle related local aileron chord fraction useful under standing dihedral based understanding ailerons vice versa Some informa tion can applied aileron airplanes estimating power ailerons good rule thumb ailerons modest deflections higher Reynolds numbers about 02 chord 10 aileron deflection equals about 05 change angle attack chord August 1988 95 16 14 12 10 Delta Alpha degrees 8 6 4 2 0 48/ TS FUN-TO-FLY SPORTS AIRCRAFT SLOW AND STABLE WITH 25 ENGINE FOR TRAINING FAST AND FULLY AEROBATIC WITH 40 ENGINE SPECIFICATIONS WINGSPAN50 IN WING AREA500 50 IN LENGHT34 IN WEIGHT31/2 4 LBS ENGINE25 40 KIT FEATURES BUILT UP WING &FUSEL SELECT BALSA SPRUCE & LIGHT PLYWOOD ALL PARTS MACHINED & FITTED PHOTOILLUSTRATEDCONSTRUCTIONBOOK oCOMPLETE HARDWARE PACKAGE 5995 TERMS KITS IN STOCK FORCHECK MONEY JER IMMEDIATE DELIVERYOR COD CASH ADD$400 FOR SHIPPING DEALER INQUIRIESjj~ ... ADD$300 FORCOD INVITEDARIZONA RESIDENTS ADD 1109 SOUTH PLAZA WAY #335FLAGSTAFF AZ 860016% FOR SALES TAX true square up After light sanding cut opening cowl seal up well last finish coat resin inside out Finishing painting Give model final sanding 400-grit sandpaper before filling dents blending everything Model Magic Filler Apply coat K&B Finishing Resin followed sand ing 400-grit paper dry Add second light coat resin go over model again 400-grit sandpaper applied two coats gray NAPA auto lacquer primer dry lightly sanded 600-grit sandpaper Two coats glossy black Perfect Paint Cheveron sprayed rest trim paint decals added coat clear satin sprayed used Chev eron Perfect Paint exclusively its easi est forgiving paint likely encounter Flying first order business check model balances centerof-gravity shown plan better yet make airplane little nose-heavy Before connecting lines certain plane will roll straight forward outside circle adjustable nose gear comes handy operation good friend Indianapolis Steve Ashby gave helpful hand starting engines first flight started outboard engine leaned out started leaned out inboard en gine match outboard Boy let tell crowed inboard matched outboard pure magic ears What beauti ful hypnotic sound just stood like plant soaking up until Steve ask going merely stand planning fly know answer lieve fly did day P-61 has ter rific flier never letdown Its very sta ble smooth wind touch-andgo maneuvers great wing tank drops 19 engines provide model adequate power thing go something biggerdont go less Whether flown competition purely fun Black Widow has consistently winner modeler cant ask Dihedral/Beron-Rawdon Continued page 95 moment fractions panel simply multiplied panel dihedral gle summed find EDA Further examples provided Figure 1 have EDA 100 Analogy ailerons amount dihe dral wing panel has determines its roll power plane yawed Thus plane flat center panel center panel makes no contribution roll power tip panels everything ap proximately equivalent aileron wing partial-span barn door ailerons V-dihedral wing makes equal contribu tion delta alpha-wise along length wing analogous strip aile rons taper proportion wing chord other analogies illus trated Figure 6 Note analogies may turned around used better understand function ailerons instance can see Figure 4 05 semi-span barn door ailerons will about 65% power ful full-span strip ailerons same percentage chord Transitional maneuvers steadystate maneuvers such rolling circling managed very well rudder eleva tor airplanes transitional maneuvers such initiating ending roll maneuver weak point because double series events required initiate end maneuver example series events re quired transition rapidly straight flight steady-state turn fairly com plex large rudder deflection accelerates plane yaw axis As plane comes yawed begins accelerate roll axis As plane approaches maxi mum yaw angle rudder deflection se lected plane decelerates yaw until maximum yaw angle reached air plane underdamped yaw due heavy wing tips undersized rudder may overshoot steady-state maximum yaw angle oscillate briefly about maximum angle Shortly after plane reaches maximum yaw angle maximum roll rate achieved Rudder deflection held until desired bank angle ap proached rudder neutralized airplane yaws back zero yaw airplane stops rolling again delays acceleration deceleration As can see order plane roll first must yaw order stop rolling must stop yawing order min imize lag between control input re sponse yaw roll acceleration decel eration should maximized achieved large fin/rudder long tall moment arm generous dihedral light weight airplane extremities namely wing tips tail group extremities overweight vertical stabilizer undersized too short moment arm plane will difficult fly precisely Its response will slow start will tend coast past desired re sponse prompting control input op posite direction input may also overshot airplane will end up wal lowing around will force pilot very slow smooth control puts giving up potential rapid pre cise control dihedral angle insufficient larger yaw excursions will necessary gener ate desired roll response will make planes response sluggish will reduce maximum roll rate Conversely plane has ample dihe dral lightweight extremities long tail mo ment generous vertical stabilizer its handling can immediate precise powerful General comments some inter esting properties point out about beha vior dihedral given airplane roll moment generated function yaw angle airspeed noteworthy overall angle attack impor tant unless airplane nearly stalled speed yaw angle same 166 Model Aviation airplane will roll same direction same speed upright upside down 0-g dive true because roll moment generated equal opposite changes angle attack left wing right Within wings unstalled range angle tack change lift per change angle attack approximately constant cause change matters base angle attack important Note also because equal opposite change yawing airplane will cause change total lift gener ated nice feature able roll thermal having simultane ously compensate pitch However air planes high rates yaw roll possibility gyroscopic coupling yaw roll axes yielding unex pected pitch-up response due gyroscopic precession problem coordi nated aileron aircraft since axis being spun time Swept-wing arrangements couple yaw roll much like dihedral doesbut some important differences yawed swept wing generates roll moment differ ence effective length wings wings still produce roughly same amount lift since have same area roughly same angle attack wing longer other has leverage means roll moment swept wing related to tal lift being produced yaw angle plane yawed 1 g roll mo ment will same independent speed pulling three gravities roll moment will three times great 0-g dive no roll mo ment upside down 1 g roll moment reversed Radio Con trol pure swept-wing model dihe dral ailerons will very tricky air plane fly well swept-wing airplanes ailerons emphasis rudder coordina tion will prevent unexpected responses Summary conclusions dihedral arrangement crucial handling roll axis Dihedral provides coupling between yaw roll roughly proportional Equivalent Dihedral Angle EDA yaw angle rolling moment wing can com puted based its dihedral arrangement yaw angle airspeed wingspan wing area planform Different dihedral arrangements have same roll moment otherwise equal V-dihedral wing said have Equivalent Dihedral Angle equal dihedral angle V-dihedral wing Equivalent Dihedral Angle given dihedral arrangement may easily calcu lated Various dihedral arrangements have anal ogies aileron arrangements Transitional maneuvers weak point rudder-and-elevator airplanes Generous dihedral long tail moment arm large verti Step future AVIATION Become Aviation Electronics Technician learn repair maintain electronic equipment used aboard aircraft Actual planes used training Hangar runway campus Train just 19 months Jobs waiting CALL NOW 1-800-758-5757 CLOVER PARK Vocational Technical Institute 4500 Steilacoom Blvd SW Tacoma WA 98499-4098 FAA Repair Station #4466 cal stabilizer lightweight wing tip pan els tail group minimize transitional shortcomings roll moment dihedral wing dependent overall angle attack Swept wings behave quite differently dihedral wings RC Soaring/Blakeslee Continued page 54 Adjustable preset trims Launch Cruise Speed Simple switch-selection simplifies pilots work during critical launch sequences In-flight setup changing Switch planes config uration on-the-fly try Out new adjustments enhance performance during particular events Landing position flap threshold selection Al lows set trip-point triggers aile ron spoiler deployment Works Airtronics FM/PPM FM/PCM receivers Initially Module 7SP Other brands added deal contact CSL make reserva tion have transmitter converted will send shipping kit sending transmitter work takes about 10 days ATRCS-modified transmitter re turned users manual explains program using examples illustrations Dur ing setup sequence asked inputs through menu-style prompts Special program features arc designed help enter correct information prevent accidental loss set ups Full information available fmm CSL 1361 Fallen Leaf Dr Milpitas CA 95035 can call 408 946-4142 SM Sailplanes Vince Parizek produces limited number Sailplane mostly Scale kits Kits may best word describe since Vinces planes appear pretty completely fin ished Lets have Vince tell us about himself well get specs two big Scale Sallplanes Just let know about background have involved RC Gliders years have building own Gliders quite some time grew up Europe became interested Scale Glid ers Since arriving States 1968 found basically no Scale ships made concerned however because could purchased Germany past few years drop dollar has put price out reach average modeler So decided offer experience Scale enthusiasts reasonable prices Because still hobby make kit myself production low waiting list stands about four weeks SMs two Scale ships Start & Flug H101 Salto 44-meters wingspan fourmeter Schleicher AS-W 17 Both have white gel coat epoxy glass fuselages foam wings sheeted obechi wood wings have ply wood spars plus carbon fiber reinforcement Aile ron spoiler areas reinforced twoounce glass cloth Tail surfaces also obechi covered foam Individual specs Salto fuselage 67in long wing area 1140 sq weight 85 lb wing loading 16-18 oz per sq ft airfoil modified Ritz II AS-W 17 specs include fuselage 59-in long wing area 1020 sq weight seven pounds wing loading 14 oz per sq ft airfoil modified Ritz III Both planes available basic com plete kit explained easily listing what complete kit gives leading edges wing tips installed shaped precut aile rons spoilers installed precut plywood pieces radio installation set decals Salto complete kit includes wheel basic complete kits AS-W 17 $289 $385 respectively Salto kits $425 $515 full-size AS-W 17 has 20-meter span model / scale Seventeen has enormously popular subject modelers H101 Salto much rarer subject Its maker offshoot Glasfiugel factory first flew 1971 wings Standard August 1988 167