So, no aeronautical engineer here, but I'd note - despite all of them having wings - that the Cherokee 140 in which I first soloed, the Cessna 150 which followed, and the Cessna 172 (most recent but years ago) all have very different flying characteristics and glide speeds, at least as nearly as I recall.
At the very least, the weight of the engine upfront and the drag of a prop produces, it seems, a different dynamic when it ceases to function.
Is not the wing of a glider designed to sustain lift without power, and therefore being at least subtilely different and with different handling requirements/ability from that of an airplane designed to produce lift or lose it) with an engine?
What you are saying is not incorrect. It is probably the typical understanding of a lot of pilots.
But it is far from complete or comprehensive enough, IMHO.
At some superficial level, all types of fixed-wing aircraft work slightly differently - some
very differently. Mostly, that's a function of built-in stability characteristics of the overall aircraft, wing plan, wing shape, control surface size, power-loading, etc.
At a much more profound level, and despite
any specifics of make or model,
all fixed-wing aircraft work in
precisely the same way. They all work according to precisely the same aerodynamic principles. Therefore, ultimately, they are all controlled (or not) according to those same aerodynamic principles. Furthermore, regardless of shape, size, or any other characteristics of A/C design, the aerodynamic principles that make airplanes work ALL require energy inputs, and therefore the management of whatever those energy inputs may be.
Glider, competition glider, 152, 747, space shuttle, piper cub... the pilot MUST be able to fly the aircraft in all phases of flight based on the pilot's intellectual understanding of the aircraft systems and their energy states and energy needs. But, that's not really good enough. That "understanding" isn't just for passing a test and moving on. That "understanding" must have been ingested and internalized so deeply as to have become intuitive to the pilot... almost instinctive.
As to energy management, for the same reasons mentioned above, ALL fixed wing aircraft - engines or no - require a deep (ideally, an intuitive) sense and application of energy management during all phases of flight, but particularly the "critical" phases. Energy may come from different sources, but whatever its source, it must still be managed precisely and judiciously.
As to
"sustain[ed]
lift without power"... Well, there we venture into the realm of perpetual motion. No aircraft can indefinitely sustain lift without an energy input. The energy may come from heat transformed into upward flowing kinetic energy (thermal updraft) or from kinetic energy deflected upward (orographic updraft), or from the conversion of dinosaur hay into the chemical energy stored in hydrocarbon chemical bonds, and then into heat and the kinetic energy created by a motor, but it MUST come from somewhere. No aircraft can fly forever unless the energy-input source lasts forever. And no pilot can fly forever - or, usually, even for a short time - if he doesn't understand the basic aerodynamics of airfoil relationships and how to manage the energy which powers those airfoils.
Lastly, let me leave you with this - EVERY powered, fixed-wing aircraft is ALSO a glider if it is flown correctly. Maybe not a very efficient glider, but a glider nevertheless. When the engines of a powered fixed-wing aircraft stop turning, pilots MUST understand that. It's precisely when the engines stop turning that a pilot's deepest, most intuitive understanding of airplane control and energy management become MOST critical.
To return to the origin of this thread digression... I hope this wee exegesis suffices to support my previously stated humble opinion that a prerequiste of becoming a powered pilot should be to become a glider pilot. That's where all the basic learning is easiest to ingest and most profoundly digested. At the end of the day, a pilot's basic job is simply to be a competent, practical translator of energy into lift - of physics into control of whatever aircraft he's flying.