▁for ▁light ening ▁the ▁air frame . ▁This ▁prototype ▁also ▁featured ▁mounted ▁under ▁wing ▁supports , ▁to ▁help ▁stop ▁the ▁plane ▁when ▁land ed . ▁▁ 3 4 6 - 1 ( A ) ▁- ▁On ▁ 5 ▁May ▁ 1 9 4 9 , ▁construction ▁of ▁ 3 4 6 - 1 ▁was ▁finished . ▁It ▁had ▁a ▁ro cket ▁engine ▁mock ▁up ▁installed , ▁and ▁incorpor ated ▁some ▁minor ▁changes ▁in ▁the ▁rud der ▁and ▁tail ▁design . ▁▁ 3 4 6 - 2 ( D ) ▁- ▁The ▁same ▁as ▁ 3 4 6 - 1 , ▁but ▁the ▁ro cket ▁engines ▁fitted . ▁▁ 3 4 6 - 3 ▁- ▁Only ▁plane ▁that ▁fle w ▁ro cket - engine ▁power ed , ▁and ▁twice ▁went ▁trans onic . ▁ ▁Oper ators ▁ ▁Soviet ▁Air ▁Force ▁ ▁Spec ifications ▁( 3 4 6 - 3 ) ▁ ▁See ▁also ▁ ▁References ▁ ▁Category : 1 9 4 0 s ▁German ▁experimental ▁aircraft ▁Category : 1 9 4 0 s ▁Soviet ▁experimental ▁aircraft ▁Category : World ▁War ▁II ▁experimental ▁aircraft ▁of ▁Germany ▁Category : G erm any – S ov iet ▁Union ▁relations ▁Category : Cancel led ▁aircraft ▁projects ▁Category : R ocket - power ed ▁aircraft ▁D FS ▁ 3 4 6 ▁Category : S ie bel ▁aircraft ▁Category : M id - wing ▁aircraft ▁Category : A ircraft ▁first ▁flow n ▁in ▁ 1 9 4 8 <0x0A> </s> ▁Francisco ▁J ara ▁Gar rib ay ▁( born ▁ 3