Ballard used the term "kiting" to describe how the Titanic traveled horizontally as well as vertically on its way to the bottom, which in part could explain the difference between its last reported position on the surface and where it is now (the other part being the accuracy of the surface position). Kiting might be a better term for the Electra under water than gliding. It seems to me that an airplane -- in the air-- that was unable to maintain flight but retained enough of its flight surfaces might travel some way horizontally as well as vertically before hitting the ground. An airplane that suffered a sufficiently catastrophic in-flight breakup just falls straight down. This is Ric's area of expertise (aircraft accident investigation) and he may have some data on the trajectory of damaged aircraft on their way to the ground.
Another consideration, though, is that this airplane (the Electra after it washes off the reef) was not in air, which offers little resistance to falling solid objects that have little surface area (thus, for example, when Galileo dropped two different-sized cannon balls from the Campanile de Pisa, the difference in air resistance did not materially affect the observation that they fell at the same speed), but in water. Displacement (what floats your boat) means even massive objects in water behave differently when submerged (their apparent weight is reduced by an amount equal to the weight of the water they displace), and water offers more resistance than does air to objects moving through it, such that they may not fall straight down. This of course is affected by the density of the object (two cannon balls dropped in water might not fall at different rates), and whether the water is still or in motion (how much force it can apply to the object). Moving water has enough force to push big pieces of iron from the Norwich City a considerable distance horizontally.
The Electra, in order to be able to fly, was a lot less dense than iron -- in total, of course -- certain parts by themselves were more dense -- so depending on how much was still in one piece, perhaps it could travel some way, even if it was no longer airworthy, and even if it was no longer what we would consider buoyant.
Just inviting some discussion.
LTM,
Don