ling ▁motion , ▁a ▁second ▁model ▁was ▁built ▁of ▁al umin um ▁and ▁released ▁from ▁the ▁window ▁of ▁a ▁car . ▁As ▁hoped , ▁the ▁t umb ling ▁quickly ▁slow ed ▁the ▁package ▁to ▁safe ▁spe eds . ▁The ▁team ▁then ▁started ▁work ▁on ▁a ▁radio - clear ▁version ▁using ▁fi berg lass ▁rein for ced ▁pl astic . ▁ ▁While ▁they ▁worked ▁on ▁the ▁design , ▁the ▁Division ▁of ▁Elect rical ▁Engineering ▁was ▁working ▁on ▁a ▁production ▁radio ▁system . ▁After ▁about ▁two ▁years ▁of ▁development , ▁everything ▁was ▁ready ▁and ▁the ▁first ▁experimental ▁C PI ▁was ▁assemble d . ▁Among ▁the ▁many ▁tests , ▁early ▁examples ▁were ▁fired ▁on ▁a ▁ro cket ▁s led ▁at ▁spe eds ▁up ▁to ▁ 3 7 0   km / h ▁off ▁the ▁top ▁of ▁a ▁cl iff ▁formed ▁by ▁a ▁former ▁gra vel ▁pit . ▁ ▁These ▁tests ▁were ▁followed ▁by ▁production - setting ▁releases ▁from ▁aircraft . ▁In ▁this ▁case ▁the ▁C PI ▁was ▁placed ▁inside ▁a ▁cyl ind rical ▁re cess ▁on ▁the ▁outside ▁of ▁the ▁aircraft ▁fus el age , ▁normally ▁near ▁the ▁tail . ▁The ▁upper ▁cur ved ▁portion ▁of ▁the ▁C PI ▁project ed ▁into ▁the ▁wind , ▁providing ▁a ▁constant ▁lift ▁when ▁the ▁aircraft ▁was ▁in ▁motion . ▁This ▁was ▁counter ed ▁by ▁a ▁spring ▁l atch ▁that ▁would ▁automatically ▁release ▁in ▁the ▁case ▁of ▁a ▁sudden ▁dec eler ation . ▁ ▁Com mer cial ▁production ▁When ▁development ▁was ▁completed ▁in ▁ 1 9 5 9 , ▁production