Ok, found the plane - attached the ballasts - went back on shore to set of the detonator - can't find it! It starts beeping when I get close, but I can't see it. Anyone know the secret, or is this a glitch???

In your inventory equip it and press the fire button.

Do you have the detonator out as a weapon? Its on the weapons list. Otherwise, it might be a glitch, or the game might not be "floating" right. (B-29 will "float" when the detonator is activated)

Thank you and Thank you! Didn't realize detonator was in weapon inventory! I can now move on!!!! Thanks again to both of you!!!