The deployable ballast is a quest item that attaches to the B-29 under each wing, between the engines and the propellers. Once detonated, the plane is able to float on the ballasts.
During Volare!, they have to be put under each wing on the B-29 as stated above. Lake Mead is a rad-free but very deep lake, so you need to talk to Loyal about getting to the plane safely if you don't feel like chancing it. He will send you to his assistant, Jack. Jack will say he can help you, but in order to do that, you need to either bring him a pressure cooker or pass a science check of 45. If you want to find a pressure cooker quickly, there should be one in the kitchens at Nellis AFB. Once you have the cooker, he will give you the Rebreather, which allows you to breathe underwater. Attach the ballast and complete the quest by going over to the quest marker and activating Loyal's detonator.
- If the player attaches the ballasts on the plane and then goes back to Loyal and talks about the plane, Loyal will give the player two additional ballasts, which can't be removed from one's inventory even after the quest (because they'll still be marked as quest items). This can only be fixed with console commands.
- The tail of the plane has a glitch where you will go through it but you can't get back out and the only way is to reload your last save.