 The McDonnell XF @-@ 85 Goblin was an American prototype fighter aircraft conceived during World War II by McDonnell Aircraft . It was intended to be deployed from the bomb bay of the giant Convair B @-@ 36 bomber as a parasite fighter . The XF @-@ 85 's intended role was to defend bombers from hostile interceptor aircraft , a need demonstrated during the Doolittle Raid , in which the B @-@ 36 was used to launch the raid on Tokyo . The XF @-@ 85 was a conventional single-seat fighter with a 1000-pound bomb in its nose , a 30