There is speculation that a B-29 (s/n 44-61721) ended up in Red Lake in Northern Minnesota, on 15 July 1945, although it has never been located. The crew bailed out at 9,500 ft (at night) due to a fuel leak in the aircraft after taking off from Duluth. The flight engineer was unconscious at the time bail out was ordered, but he was pushed out the hatch and landed safely. The crew was recovered near Big Fork, MN, slightly more than half way between Duluth and Red Lake. The crew stated the aircraft was on autopilot on a heading that would have it heading towards Montana.
http://minnesotabrown.com/2014/03/70-year-mystery-skies-itasca-county.htmlhttp://ww2f.com/threads/b-29-disappears-after-crew-bales-out-1945.48637/I spoke with a gentleman (Richard G. King) who was to have crewed that aircraft out of Pyote, TX, but his aircraft commander refused to take the airplane due to a previously squawked fuel leak. Richard was a central fire control gunner on -29's and commented that the autopilot was not an altitude holding autopilot. He also pointed out that bail out from the B-29 was accomplished by exiting through a hatch that required dropping the nose gear. If the autopilot was a pitch hold type system, it might not be unreasonable that the additional drag of the nose gear hanging down induced a slow rate of descent that the autopilot would not have compensated for.
Lower Red Lake is ~66 Nm from the location where some of the crew were recovered. If the aircraft continued on at 200 mph, it would have required a rate of descent of ~360 ft/min to descend from 9,500 ft MSL at Napoleon Lake (location where one crew member was recovered) to 1,200 ft MSL at Red Lake (approximate altitude of Red Lake).
This accident is listed on this Wikipedia page (see 15 July 1945);
https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_military_aircraft_(1945%E2%80%931949)I'm not familiar with the B-29 autopilot, so I have no idea if this is a reasonable theory or not. Otherwise, the B-29 could be in the mountains/woods of Montana or Canada, or who knows where...