▁periods ▁was ▁used . ▁▁ ▁Hence ▁US ▁acceler om eters ▁either ▁consisted ▁of ▁the ▁flo ated ▁type ▁or ▁the ▁g ase ous ▁bearing ▁type ▁with ▁the ▁US ▁Army ▁and ▁US ▁Space ▁program ▁re lying ▁on ▁the ▁later ▁type ▁of ▁instrument . ▁ ▁References ▁" Develop ments ▁in ▁the ▁Field ▁of ▁Autom atic ▁Gu id ance ▁and ▁Control ▁of ▁Rock ets ", ▁Walter ▁H ae us ser mann , ▁The ▁B end ix ▁Corporation , ▁Hun ts ville , ▁A la . ▁V OL . ▁ 4 , ▁NO . ▁ 3 ▁J . ▁G UID ANCE ▁AND ▁CON T RO L ▁MA Y - J UN E ▁ 1 9 8 1 , ▁History ▁of ▁Key ▁Techn ologies ▁A I AA ▁ 8 1 - 4 1 2 0 . ▁From ▁A I AA ▁American ▁Institute ▁for ▁Aer onaut ics ▁& ▁A str onaut ics ▁Digital ▁Library ▁A I AA ▁ 2 0 0 1 - 4 2 8 8 , ▁" The ▁P end ul ous ▁Integr ating ▁Gy ros cope ▁Acc eler ometer ▁( PI GA ) ▁from ▁the ▁V - 2 ▁to ▁Tr ident ▁D 5 , ▁the ▁Str ateg ic ▁Inst rument ▁of ▁Cho ice ", ▁R . E . ▁Hop kins ▁The ▁Charles ▁St ark ▁Dra per ▁Labor atory , ▁Inc . ▁Cambridge , ▁MA , ▁Dr . ▁Fritz ▁K . ▁Mu eller , ▁Dr . ▁Walter ▁H ae us ser mann , ▁Hun ts ville , ▁AL , ▁Gu id ance , ▁Navigation , ▁and ▁Control ▁Conference