 flight using an F4F Wildcat modified with breakaway wingtips. F8F flight tests were subsequently accomplished by Corky himself to include landings with only one wingtip broken off to demonstrate controllablity in the asymmetric condition. Demonstrated and proven, the safety tip was standard on production Bearcats.
There were, however, fatal crashes associated with the breakaway of only one wingtip. One was a Blue Angel who failed to pull out of the downward finish to a Cuban 8 at an airshow in September 1946. Another was during pullout from a dive-bombing run. The resulting sudden roll reduced the effectiveness of a pullout to less than that needed to avoid hitting the ground.** That only one wingtip came off instead of both was ascribed to variation in manufacturing tolerance (size of rivet holes, clamp-up load, skin thickness, etc) in the structure and a difference in the weakening over time of the weak-link structure in each wing caused by carrier landings and buffet during high-g maneuvers.
The response was to add a ballistic backup to the weak link to insure that both tips came off at the same time. Primacord (a thin plastic tube filled with explosive) and a microswitch were added to the break point and the installations on each wing were connected electrically. If the microswitch opened on one wing, indicating that the wingtip had separated, a circuit would close to detonate the Primacord on the other wing, insuring that its wingtip separated as well. Corky demonstrated the removal of one wingtip ballistically in flight.
If there was understandable nervousness about bombs embedded in aircraft structure, it wasn't enough to insure that adequate safety measures were established or observed although the installation was identified with a red line on at least some Bearcats.
Capt Paul Anderson collection via Jan van Waarde
It was therefore probably inevitable that a short circuit during maintenance on an F8F caused the wing tip to separate, killing a sailor. According to the Flight Manual "it has not been possible to make and maintain a continuously reliable installation of the explosive wing-tip-shedding device in service airplanes." The result was an airframe change in early 1949 to delete the Primacord installation and eliminate the weak link with a structural beef-up of the wing.
* A somewhat different story of the genesis of the Bearcat than the one provided by Corky in his monograph can be read here: http://thanlont.blogspot.com/2011/02/conception-of-f8f-bearcat.html
** Contrary to what you might think, the loss of lift from the wing tip was usually accompanied by a net increase in lift from the rest of the wing rather than a decrease. The nose-down pitching moment of the wing was reduced by the loss of the wing area but the nose-up pitching moment of the horizontal tail remained the same, resulting in an increase in the angle of attack of the wing at the amount of aft stick when the tips came off. If the increase didn't exceed the angle of attack for stall, lift would therefore increase.