Ok the B-2 predacesor the XB-35 was also a flying wing and was unstable due to the lack of a tail rudder, but it was remedied due to the way the prop engine housing made small rudder like humps.
look at the engine housing in the back.
When the jet engines were installed it was found too dificult to control the XB-49 due to the loss of the "tail" element. So 4 small tail units were installed o compasate for the loss, as seen blow. A XB-49 aircraft crashed in 1948 due to such problems at the Edward airforce base. Edwards base was named after Capt. Glen Edwards who died in the crash.
Now the B-2 infact has the same problems and in someceases is worse, the only way it says in the air is with computer assisted flight, if the computers were to be damaged it would crash, it is said that it could not be flown without them. The B-2 is too unstable to be flown by the pilot alone.
