For high performance safety fiberglass propeller ideal ice free flight CL RC racing events first two part article authors cover making \ mold U Text Photos Tom Hail Larry \Fagan * 9 THE ADVANTAGES fiberglass propsstrength rigidity safety su perior performancehave made popular item competitive modeling events Fiberglass props useful ever resistance dc-pitching desired whenever high rpm encountered fiberglass prop will resist flying pieces high rpm makes ideal choice free flight CL RC racing events Its rigidity lends itself events such Carrier require engine run rpm because prop does throb low rpm like nylon prop occasionally does addition performance prop can colored different dyes event such Stunt planes appearance considered part tal points prop adds effect paint scheme might help Another advantage fiberglass prop easily reproduced Molding favorite prop have spent considerable time carving pitching finishing will allow reproduce far less effort doing similar modifications new prop Also can make modifications ruining prototype Breaking copy far less traumatic breaking original may have hours work Because fiberglass pops popu larity different events has difficult obtain insure adequate supply realized needed make own concerned about safety performance aspects building props well ease duplication talk Les Pardue Albuquerque alleviated fears con vinced us should proceed immediately next two weeks spent obtain ing various materials involvedwhich VE goodespecially considering first An article carbon fiber props May 1972 issue Aeromodeller helped first prop different story however although taught us couple things First amount glass should absolute maximum Second prop will increase maximum rigidity about week after molding last factor important because means maximum economy motion can realized using weekend turn out number props second weekend 34 Model Aviation HowtoMold U Fiberglass Props totalled about $4000 figured enough material make about 600 7-inch props size terested approximate cost com mercially manufactured prop about $400 Starting Saturday afternoon tried first prop mold very Ins maxerisas vor praaucng ins mou ars uvsaule around house plastic fiberglass supply shops plethora excellent propellers exists average modeler seriously racing ultra high-rpm running will benefit feature After PVA mold release has completely dried tape around struc ture making mold hold Bondo After clay has taped clamp two pieces wood along sides keep tape bulging out mold poured September 1978 35 clay has shaped accommodate prototype prop will used form mold blank will form top portion mold knife clay carefully sliced away edges prop sharp angles clay smoothed keep flaws Out mold After clay trimmed smoothed piece drill rod placed through hub prop creating hole mold poured entire structure including drill rod coated two coats PVA PVA water-based mold release Mold carved out ends allow fiberglass stick Out prop being constructed Most carving cleaning done mold still warm Edges mold filed smooth easy handling separation mold resin sticks during propeller construction Part II 36 Model Aviation After Bondo has bean thoroughly mixed should about con sistency milkshake few air bubbles Bondo carefully poured parts mold entire struc ture left harden ventilated area After Bondo has hardened tape clay excess material removed top half mold Prop carefully removed after mold has oeen carvea ne tnIn sneet PVA left prop mold easily washed off warm water Labeling finished mold easy identification helpful Once have through routine will making other maids September1978 37 mold has completely hardened cooled wasned water remove clay dust particles After mold has finished propeller replaced drill rod coated PVA surfaces mold now coated twice PVA allowed dry nothing procedure seems difficult top halt mold now finished retaped clamped Jaw hIS ready have other half mold poured mold after has hardened now ready taken apart finished Note clean work area has throughout balancing finishing Another excellent winter project summer flying Mold Materials Equipment first step producing mold obtain required materials include modeling clay finishing resin K&B fine auto motive body filler such Ditzler 999 compatible K&B resin Masking tape mold release agent PVA wax paper also required Equipment will need mixing bowl preferably expendable putty knife modeling knife long bladed knife old butcher knife will drill drill rod diameter engines drive shaft C clamps two boards measuring about 3 X 12 X wish duplicate should carefully brought desired pitch prop should also thinned same thickness want fiberglass prop 7 diameter prop would vicinity 100 approxi mately mid-blade thinning approxi mately 050 tips Other approxi mate mid-blade thicknesses 5050 6075 8 135 Once prop properly dimensioned should finished very high gloss Wood props should stripped finished resin buffed because molding agent will melt varnish result rough finish Any dents scratches prop duplicated will faithfully re produced mold Procedure Begin piece clay about 1-inch square slightly longer prop duplicated Soften clay kneading until easy work important because want deform prop push bottom clay Hereafter top prop will refer front curved side airfoil bottom will re fer back flat side airfoil Continue working clay around prop until fills entire bottom Next trim clay around prop sharp angle edges blades insure easy separation completed mold point insert drill drill rod hub trim excess clay away ends clay should ex tend no further nd sides prop nd ends void appears under blade carefully work clay cover body filler will flow Carefully brush two coats mold re lease structure allowing coat dry thoroughly must wish retrieve prototype prop Tape around structure carefully form sealed trough about 1 above highest point blade Clamp taped struc ture between two boards taking care deform clay Set aside mix resin body filler should use about five golf-ballsized portions body filler enough resin thin mixture milk-shake consistency Complete step before adding catalyst because mixture goes off quite suddenly want some time allow bubbles come surface after have filled mold Take care pouring filler flows smoothly around hub entraining air After filler has set still very warm touch remove drill drill rod clay clay separates easily hot excess body filler can trimmed easily too care ful bend mold very pliable until cures completely Remove prop carefully score surface mold mold release will resemble thin water-soluble plastic coating Carve out ends mold allow fiber glass strands room pass through mold during laying up process Com plete top half mold thor oughly washing drying produce bottom half mold replace prop drill drill rod top half mold Give new structure two coats mold release allow ing coat dry completely Once again tape assembly clamp tween boards Mix body filler same consistency before pour mold still quite warm sep arate trim being careful score bend mold bend mold panic Simply clamp hot half gently back onto cured mold cools completely two halves will mate perfectly cured mold will retain its clamped shape spring back its originally warped condi tion allowed two halves cool completely before separation find stubbornly stick together heat mold hot water should find mold will separate little effort last step label mold identify prop will produce Also mark mating ends two halves will try assemble back wards molding props completes construction mold continued 38 Model Aviation
Edition: Model Aviation - 1978/09
Page Numbers: 34, 35, 36, 37, 38
For high performance safety fiberglass propeller ideal ice free flight CL RC racing events first two part article authors cover making \ mold U Text Photos Tom Hail Larry \Fagan * 9 THE ADVANTAGES fiberglass propsstrength rigidity safety su perior performancehave made popular item competitive modeling events Fiberglass props useful ever resistance dc-pitching desired whenever high rpm encountered fiberglass prop will resist flying pieces high rpm makes ideal choice free flight CL RC racing events Its rigidity lends itself events such Carrier require engine run rpm because prop does throb low rpm like nylon prop occasionally does addition performance prop can colored different dyes event such Stunt planes appearance considered part tal points prop adds effect paint scheme might help Another advantage fiberglass prop easily reproduced Molding favorite prop have spent considerable time carving pitching finishing will allow reproduce far less effort doing similar modifications new prop Also can make modifications ruining prototype Breaking copy far less traumatic breaking original may have hours work Because fiberglass pops popu larity different events has difficult obtain insure adequate supply realized needed make own concerned about safety performance aspects building props well ease duplication talk Les Pardue Albuquerque alleviated fears con vinced us should proceed immediately next two weeks spent obtain ing various materials involvedwhich VE goodespecially considering first An article carbon fiber props May 1972 issue Aeromodeller helped first prop different story however although taught us couple things First amount glass should absolute maximum Second prop will increase maximum rigidity about week after molding last factor important because means maximum economy motion can realized using weekend turn out number props second weekend 34 Model Aviation HowtoMold U Fiberglass Props totalled about $4000 figured enough material make about 600 7-inch props size terested approximate cost com mercially manufactured prop about $400 Starting Saturday afternoon tried first prop mold very Ins maxerisas vor praaucng ins mou ars uvsaule around house plastic fiberglass supply shops plethora excellent propellers exists average modeler seriously racing ultra high-rpm running will benefit feature After PVA mold release has completely dried tape around struc ture making mold hold Bondo After clay has taped clamp two pieces wood along sides keep tape bulging out mold poured September 1978 35 clay has shaped accommodate prototype prop will used form mold blank will form top portion mold knife clay carefully sliced away edges prop sharp angles clay smoothed keep flaws Out mold After clay trimmed smoothed piece drill rod placed through hub prop creating hole mold poured entire structure including drill rod coated two coats PVA PVA water-based mold release Mold carved out ends allow fiberglass stick Out prop being constructed Most carving cleaning done mold still warm Edges mold filed smooth easy handling separation mold resin sticks during propeller construction Part II 36 Model Aviation After Bondo has bean thoroughly mixed should about con sistency milkshake few air bubbles Bondo carefully poured parts mold entire struc ture left harden ventilated area After Bondo has hardened tape clay excess material removed top half mold Prop carefully removed after mold has oeen carvea ne tnIn sneet PVA left prop mold easily washed off warm water Labeling finished mold easy identification helpful Once have through routine will making other maids September1978 37 mold has completely hardened cooled wasned water remove clay dust particles After mold has finished propeller replaced drill rod coated PVA surfaces mold now coated twice PVA allowed dry nothing procedure seems difficult top halt mold now finished retaped clamped Jaw hIS ready have other half mold poured mold after has hardened now ready taken apart finished Note clean work area has throughout balancing finishing Another excellent winter project summer flying Mold Materials Equipment first step producing mold obtain required materials include modeling clay finishing resin K&B fine auto motive body filler such Ditzler 999 compatible K&B resin Masking tape mold release agent PVA wax paper also required Equipment will need mixing bowl preferably expendable putty knife modeling knife long bladed knife old butcher knife will drill drill rod diameter engines drive shaft C clamps two boards measuring about 3 X 12 X wish duplicate should carefully brought desired pitch prop should also thinned same thickness want fiberglass prop 7 diameter prop would vicinity 100 approxi mately mid-blade thinning approxi mately 050 tips Other approxi mate mid-blade thicknesses 5050 6075 8 135 Once prop properly dimensioned should finished very high gloss Wood props should stripped finished resin buffed because molding agent will melt varnish result rough finish Any dents scratches prop duplicated will faithfully re produced mold Procedure Begin piece clay about 1-inch square slightly longer prop duplicated Soften clay kneading until easy work important because want deform prop push bottom clay Hereafter top prop will refer front curved side airfoil bottom will re fer back flat side airfoil Continue working clay around prop until fills entire bottom Next trim clay around prop sharp angle edges blades insure easy separation completed mold point insert drill drill rod hub trim excess clay away ends clay should ex tend no further nd sides prop nd ends void appears under blade carefully work clay cover body filler will flow Carefully brush two coats mold re lease structure allowing coat dry thoroughly must wish retrieve prototype prop Tape around structure carefully form sealed trough about 1 above highest point blade Clamp taped struc ture between two boards taking care deform clay Set aside mix resin body filler should use about five golf-ballsized portions body filler enough resin thin mixture milk-shake consistency Complete step before adding catalyst because mixture goes off quite suddenly want some time allow bubbles come surface after have filled mold Take care pouring filler flows smoothly around hub entraining air After filler has set still very warm touch remove drill drill rod clay clay separates easily hot excess body filler can trimmed easily too care ful bend mold very pliable until cures completely Remove prop carefully score surface mold mold release will resemble thin water-soluble plastic coating Carve out ends mold allow fiber glass strands room pass through mold during laying up process Com plete top half mold thor oughly washing drying produce bottom half mold replace prop drill drill rod top half mold Give new structure two coats mold release allow ing coat dry completely Once again tape assembly clamp tween boards Mix body filler same consistency before pour mold still quite warm sep arate trim being careful score bend mold bend mold panic Simply clamp hot half gently back onto cured mold cools completely two halves will mate perfectly cured mold will retain its clamped shape spring back its originally warped condi tion allowed two halves cool completely before separation find stubbornly stick together heat mold hot water should find mold will separate little effort last step label mold identify prop will produce Also mark mating ends two halves will try assemble back wards molding props completes construction mold continued 38 Model Aviation
Edition: Model Aviation - 1978/09
Page Numbers: 34, 35, 36, 37, 38
For high performance safety fiberglass propeller ideal ice free flight CL RC racing events first two part article authors cover making \ mold U Text Photos Tom Hail Larry \Fagan * 9 THE ADVANTAGES fiberglass propsstrength rigidity safety su perior performancehave made popular item competitive modeling events Fiberglass props useful ever resistance dc-pitching desired whenever high rpm encountered fiberglass prop will resist flying pieces high rpm makes ideal choice free flight CL RC racing events Its rigidity lends itself events such Carrier require engine run rpm because prop does throb low rpm like nylon prop occasionally does addition performance prop can colored different dyes event such Stunt planes appearance considered part tal points prop adds effect paint scheme might help Another advantage fiberglass prop easily reproduced Molding favorite prop have spent considerable time carving pitching finishing will allow reproduce far less effort doing similar modifications new prop Also can make modifications ruining prototype Breaking copy far less traumatic breaking original may have hours work Because fiberglass pops popu larity different events has difficult obtain insure adequate supply realized needed make own concerned about safety performance aspects building props well ease duplication talk Les Pardue Albuquerque alleviated fears con vinced us should proceed immediately next two weeks spent obtain ing various materials involvedwhich VE goodespecially considering first An article carbon fiber props May 1972 issue Aeromodeller helped first prop different story however although taught us couple things First amount glass should absolute maximum Second prop will increase maximum rigidity about week after molding last factor important because means maximum economy motion can realized using weekend turn out number props second weekend 34 Model Aviation HowtoMold U Fiberglass Props totalled about $4000 figured enough material make about 600 7-inch props size terested approximate cost com mercially manufactured prop about $400 Starting Saturday afternoon tried first prop mold very Ins maxerisas vor praaucng ins mou ars uvsaule around house plastic fiberglass supply shops plethora excellent propellers exists average modeler seriously racing ultra high-rpm running will benefit feature After PVA mold release has completely dried tape around struc ture making mold hold Bondo After clay has taped clamp two pieces wood along sides keep tape bulging out mold poured September 1978 35 clay has shaped accommodate prototype prop will used form mold blank will form top portion mold knife clay carefully sliced away edges prop sharp angles clay smoothed keep flaws Out mold After clay trimmed smoothed piece drill rod placed through hub prop creating hole mold poured entire structure including drill rod coated two coats PVA PVA water-based mold release Mold carved out ends allow fiberglass stick Out prop being constructed Most carving cleaning done mold still warm Edges mold filed smooth easy handling separation mold resin sticks during propeller construction Part II 36 Model Aviation After Bondo has bean thoroughly mixed should about con sistency milkshake few air bubbles Bondo carefully poured parts mold entire struc ture left harden ventilated area After Bondo has hardened tape clay excess material removed top half mold Prop carefully removed after mold has oeen carvea ne tnIn sneet PVA left prop mold easily washed off warm water Labeling finished mold easy identification helpful Once have through routine will making other maids September1978 37 mold has completely hardened cooled wasned water remove clay dust particles After mold has finished propeller replaced drill rod coated PVA surfaces mold now coated twice PVA allowed dry nothing procedure seems difficult top halt mold now finished retaped clamped Jaw hIS ready have other half mold poured mold after has hardened now ready taken apart finished Note clean work area has throughout balancing finishing Another excellent winter project summer flying Mold Materials Equipment first step producing mold obtain required materials include modeling clay finishing resin K&B fine auto motive body filler such Ditzler 999 compatible K&B resin Masking tape mold release agent PVA wax paper also required Equipment will need mixing bowl preferably expendable putty knife modeling knife long bladed knife old butcher knife will drill drill rod diameter engines drive shaft C clamps two boards measuring about 3 X 12 X wish duplicate should carefully brought desired pitch prop should also thinned same thickness want fiberglass prop 7 diameter prop would vicinity 100 approxi mately mid-blade thinning approxi mately 050 tips Other approxi mate mid-blade thicknesses 5050 6075 8 135 Once prop properly dimensioned should finished very high gloss Wood props should stripped finished resin buffed because molding agent will melt varnish result rough finish Any dents scratches prop duplicated will faithfully re produced mold Procedure Begin piece clay about 1-inch square slightly longer prop duplicated Soften clay kneading until easy work important because want deform prop push bottom clay Hereafter top prop will refer front curved side airfoil bottom will re fer back flat side airfoil Continue working clay around prop until fills entire bottom Next trim clay around prop sharp angle edges blades insure easy separation completed mold point insert drill drill rod hub trim excess clay away ends clay should ex tend no further nd sides prop nd ends void appears under blade carefully work clay cover body filler will flow Carefully brush two coats mold re lease structure allowing coat dry thoroughly must wish retrieve prototype prop Tape around structure carefully form sealed trough about 1 above highest point blade Clamp taped struc ture between two boards taking care deform clay Set aside mix resin body filler should use about five golf-ballsized portions body filler enough resin thin mixture milk-shake consistency Complete step before adding catalyst because mixture goes off quite suddenly want some time allow bubbles come surface after have filled mold Take care pouring filler flows smoothly around hub entraining air After filler has set still very warm touch remove drill drill rod clay clay separates easily hot excess body filler can trimmed easily too care ful bend mold very pliable until cures completely Remove prop carefully score surface mold mold release will resemble thin water-soluble plastic coating Carve out ends mold allow fiber glass strands room pass through mold during laying up process Com plete top half mold thor oughly washing drying produce bottom half mold replace prop drill drill rod top half mold Give new structure two coats mold release allow ing coat dry completely Once again tape assembly clamp tween boards Mix body filler same consistency before pour mold still quite warm sep arate trim being careful score bend mold bend mold panic Simply clamp hot half gently back onto cured mold cools completely two halves will mate perfectly cured mold will retain its clamped shape spring back its originally warped condi tion allowed two halves cool completely before separation find stubbornly stick together heat mold hot water should find mold will separate little effort last step label mold identify prop will produce Also mark mating ends two halves will try assemble back wards molding props completes construction mold continued 38 Model Aviation
Edition: Model Aviation - 1978/09
Page Numbers: 34, 35, 36, 37, 38
For high performance safety fiberglass propeller ideal ice free flight CL RC racing events first two part article authors cover making \ mold U Text Photos Tom Hail Larry \Fagan * 9 THE ADVANTAGES fiberglass propsstrength rigidity safety su perior performancehave made popular item competitive modeling events Fiberglass props useful ever resistance dc-pitching desired whenever high rpm encountered fiberglass prop will resist flying pieces high rpm makes ideal choice free flight CL RC racing events Its rigidity lends itself events such Carrier require engine run rpm because prop does throb low rpm like nylon prop occasionally does addition performance prop can colored different dyes event such Stunt planes appearance considered part tal points prop adds effect paint scheme might help Another advantage fiberglass prop easily reproduced Molding favorite prop have spent considerable time carving pitching finishing will allow reproduce far less effort doing similar modifications new prop Also can make modifications ruining prototype Breaking copy far less traumatic breaking original may have hours work Because fiberglass pops popu larity different events has difficult obtain insure adequate supply realized needed make own concerned about safety performance aspects building props well ease duplication talk Les Pardue Albuquerque alleviated fears con vinced us should proceed immediately next two weeks spent obtain ing various materials involvedwhich VE goodespecially considering first An article carbon fiber props May 1972 issue Aeromodeller helped first prop different story however although taught us couple things First amount glass should absolute maximum Second prop will increase maximum rigidity about week after molding last factor important because means maximum economy motion can realized using weekend turn out number props second weekend 34 Model Aviation HowtoMold U Fiberglass Props totalled about $4000 figured enough material make about 600 7-inch props size terested approximate cost com mercially manufactured prop about $400 Starting Saturday afternoon tried first prop mold very Ins maxerisas vor praaucng ins mou ars uvsaule around house plastic fiberglass supply shops plethora excellent propellers exists average modeler seriously racing ultra high-rpm running will benefit feature After PVA mold release has completely dried tape around struc ture making mold hold Bondo After clay has taped clamp two pieces wood along sides keep tape bulging out mold poured September 1978 35 clay has shaped accommodate prototype prop will used form mold blank will form top portion mold knife clay carefully sliced away edges prop sharp angles clay smoothed keep flaws Out mold After clay trimmed smoothed piece drill rod placed through hub prop creating hole mold poured entire structure including drill rod coated two coats PVA PVA water-based mold release Mold carved out ends allow fiberglass stick Out prop being constructed Most carving cleaning done mold still warm Edges mold filed smooth easy handling separation mold resin sticks during propeller construction Part II 36 Model Aviation After Bondo has bean thoroughly mixed should about con sistency milkshake few air bubbles Bondo carefully poured parts mold entire struc ture left harden ventilated area After Bondo has hardened tape clay excess material removed top half mold Prop carefully removed after mold has oeen carvea ne tnIn sneet PVA left prop mold easily washed off warm water Labeling finished mold easy identification helpful Once have through routine will making other maids September1978 37 mold has completely hardened cooled wasned water remove clay dust particles After mold has finished propeller replaced drill rod coated PVA surfaces mold now coated twice PVA allowed dry nothing procedure seems difficult top halt mold now finished retaped clamped Jaw hIS ready have other half mold poured mold after has hardened now ready taken apart finished Note clean work area has throughout balancing finishing Another excellent winter project summer flying Mold Materials Equipment first step producing mold obtain required materials include modeling clay finishing resin K&B fine auto motive body filler such Ditzler 999 compatible K&B resin Masking tape mold release agent PVA wax paper also required Equipment will need mixing bowl preferably expendable putty knife modeling knife long bladed knife old butcher knife will drill drill rod diameter engines drive shaft C clamps two boards measuring about 3 X 12 X wish duplicate should carefully brought desired pitch prop should also thinned same thickness want fiberglass prop 7 diameter prop would vicinity 100 approxi mately mid-blade thinning approxi mately 050 tips Other approxi mate mid-blade thicknesses 5050 6075 8 135 Once prop properly dimensioned should finished very high gloss Wood props should stripped finished resin buffed because molding agent will melt varnish result rough finish Any dents scratches prop duplicated will faithfully re produced mold Procedure Begin piece clay about 1-inch square slightly longer prop duplicated Soften clay kneading until easy work important because want deform prop push bottom clay Hereafter top prop will refer front curved side airfoil bottom will re fer back flat side airfoil Continue working clay around prop until fills entire bottom Next trim clay around prop sharp angle edges blades insure easy separation completed mold point insert drill drill rod hub trim excess clay away ends clay should ex tend no further nd sides prop nd ends void appears under blade carefully work clay cover body filler will flow Carefully brush two coats mold re lease structure allowing coat dry thoroughly must wish retrieve prototype prop Tape around structure carefully form sealed trough about 1 above highest point blade Clamp taped struc ture between two boards taking care deform clay Set aside mix resin body filler should use about five golf-ballsized portions body filler enough resin thin mixture milk-shake consistency Complete step before adding catalyst because mixture goes off quite suddenly want some time allow bubbles come surface after have filled mold Take care pouring filler flows smoothly around hub entraining air After filler has set still very warm touch remove drill drill rod clay clay separates easily hot excess body filler can trimmed easily too care ful bend mold very pliable until cures completely Remove prop carefully score surface mold mold release will resemble thin water-soluble plastic coating Carve out ends mold allow fiber glass strands room pass through mold during laying up process Com plete top half mold thor oughly washing drying produce bottom half mold replace prop drill drill rod top half mold Give new structure two coats mold release allow ing coat dry completely Once again tape assembly clamp tween boards Mix body filler same consistency before pour mold still quite warm sep arate trim being careful score bend mold bend mold panic Simply clamp hot half gently back onto cured mold cools completely two halves will mate perfectly cured mold will retain its clamped shape spring back its originally warped condi tion allowed two halves cool completely before separation find stubbornly stick together heat mold hot water should find mold will separate little effort last step label mold identify prop will produce Also mark mating ends two halves will try assemble back wards molding props completes construction mold continued 38 Model Aviation
Edition: Model Aviation - 1978/09
Page Numbers: 34, 35, 36, 37, 38
For high performance safety fiberglass propeller ideal ice free flight CL RC racing events first two part article authors cover making \ mold U Text Photos Tom Hail Larry \Fagan * 9 THE ADVANTAGES fiberglass propsstrength rigidity safety su perior performancehave made popular item competitive modeling events Fiberglass props useful ever resistance dc-pitching desired whenever high rpm encountered fiberglass prop will resist flying pieces high rpm makes ideal choice free flight CL RC racing events Its rigidity lends itself events such Carrier require engine run rpm because prop does throb low rpm like nylon prop occasionally does addition performance prop can colored different dyes event such Stunt planes appearance considered part tal points prop adds effect paint scheme might help Another advantage fiberglass prop easily reproduced Molding favorite prop have spent considerable time carving pitching finishing will allow reproduce far less effort doing similar modifications new prop Also can make modifications ruining prototype Breaking copy far less traumatic breaking original may have hours work Because fiberglass pops popu larity different events has difficult obtain insure adequate supply realized needed make own concerned about safety performance aspects building props well ease duplication talk Les Pardue Albuquerque alleviated fears con vinced us should proceed immediately next two weeks spent obtain ing various materials involvedwhich VE goodespecially considering first An article carbon fiber props May 1972 issue Aeromodeller helped first prop different story however although taught us couple things First amount glass should absolute maximum Second prop will increase maximum rigidity about week after molding last factor important because means maximum economy motion can realized using weekend turn out number props second weekend 34 Model Aviation HowtoMold U Fiberglass Props totalled about $4000 figured enough material make about 600 7-inch props size terested approximate cost com mercially manufactured prop about $400 Starting Saturday afternoon tried first prop mold very Ins maxerisas vor praaucng ins mou ars uvsaule around house plastic fiberglass supply shops plethora excellent propellers exists average modeler seriously racing ultra high-rpm running will benefit feature After PVA mold release has completely dried tape around struc ture making mold hold Bondo After clay has taped clamp two pieces wood along sides keep tape bulging out mold poured September 1978 35 clay has shaped accommodate prototype prop will used form mold blank will form top portion mold knife clay carefully sliced away edges prop sharp angles clay smoothed keep flaws Out mold After clay trimmed smoothed piece drill rod placed through hub prop creating hole mold poured entire structure including drill rod coated two coats PVA PVA water-based mold release Mold carved out ends allow fiberglass stick Out prop being constructed Most carving cleaning done mold still warm Edges mold filed smooth easy handling separation mold resin sticks during propeller construction Part II 36 Model Aviation After Bondo has bean thoroughly mixed should about con sistency milkshake few air bubbles Bondo carefully poured parts mold entire struc ture left harden ventilated area After Bondo has hardened tape clay excess material removed top half mold Prop carefully removed after mold has oeen carvea ne tnIn sneet PVA left prop mold easily washed off warm water Labeling finished mold easy identification helpful Once have through routine will making other maids September1978 37 mold has completely hardened cooled wasned water remove clay dust particles After mold has finished propeller replaced drill rod coated PVA surfaces mold now coated twice PVA allowed dry nothing procedure seems difficult top halt mold now finished retaped clamped Jaw hIS ready have other half mold poured mold after has hardened now ready taken apart finished Note clean work area has throughout balancing finishing Another excellent winter project summer flying Mold Materials Equipment first step producing mold obtain required materials include modeling clay finishing resin K&B fine auto motive body filler such Ditzler 999 compatible K&B resin Masking tape mold release agent PVA wax paper also required Equipment will need mixing bowl preferably expendable putty knife modeling knife long bladed knife old butcher knife will drill drill rod diameter engines drive shaft C clamps two boards measuring about 3 X 12 X wish duplicate should carefully brought desired pitch prop should also thinned same thickness want fiberglass prop 7 diameter prop would vicinity 100 approxi mately mid-blade thinning approxi mately 050 tips Other approxi mate mid-blade thicknesses 5050 6075 8 135 Once prop properly dimensioned should finished very high gloss Wood props should stripped finished resin buffed because molding agent will melt varnish result rough finish Any dents scratches prop duplicated will faithfully re produced mold Procedure Begin piece clay about 1-inch square slightly longer prop duplicated Soften clay kneading until easy work important because want deform prop push bottom clay Hereafter top prop will refer front curved side airfoil bottom will re fer back flat side airfoil Continue working clay around prop until fills entire bottom Next trim clay around prop sharp angle edges blades insure easy separation completed mold point insert drill drill rod hub trim excess clay away ends clay should ex tend no further nd sides prop nd ends void appears under blade carefully work clay cover body filler will flow Carefully brush two coats mold re lease structure allowing coat dry thoroughly must wish retrieve prototype prop Tape around structure carefully form sealed trough about 1 above highest point blade Clamp taped struc ture between two boards taking care deform clay Set aside mix resin body filler should use about five golf-ballsized portions body filler enough resin thin mixture milk-shake consistency Complete step before adding catalyst because mixture goes off quite suddenly want some time allow bubbles come surface after have filled mold Take care pouring filler flows smoothly around hub entraining air After filler has set still very warm touch remove drill drill rod clay clay separates easily hot excess body filler can trimmed easily too care ful bend mold very pliable until cures completely Remove prop carefully score surface mold mold release will resemble thin water-soluble plastic coating Carve out ends mold allow fiber glass strands room pass through mold during laying up process Com plete top half mold thor oughly washing drying produce bottom half mold replace prop drill drill rod top half mold Give new structure two coats mold release allow ing coat dry completely Once again tape assembly clamp tween boards Mix body filler same consistency before pour mold still quite warm sep arate trim being careful score bend mold bend mold panic Simply clamp hot half gently back onto cured mold cools completely two halves will mate perfectly cured mold will retain its clamped shape spring back its originally warped condi tion allowed two halves cool completely before separation find stubbornly stick together heat mold hot water should find mold will separate little effort last step label mold identify prop will produce Also mark mating ends two halves will try assemble back wards molding props completes construction mold continued 38 Model Aviation