alt Hacker NewsSays that it's boost-only in all the literature I could see, so it can only add power to the prop not generate with it. Regardless, you don't really get into a position where you're harvesting energy in a plane - you just use less power while you're descending. Unlike in a car, most of a passenger jet's flight time is at speeds where drag (which squares with speed) basically means you'd have to nose down at a very aggressive angle to actually pick up speed without the engines providing thrust. The plane's engines are almost always under some kind of load until it is on the tarmac and slowing down so there isn't any opportunity to "regen" during a normal flight.
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> you'd have to nose down at a very aggressive angle to actually pick up speed
Sorry but what the hell are you talking about? Airliners are heavy, very aerodynamic, very easy to overspeed and they regularly actively brake on descent!
Unless there are other constraints on the approach, the point of the entire descent phase is to have the engines IDLING the whole time. The FMC actually calculates the descent profile backwards, starting from the earliest known constraint (e.g. a certain point at 5000 ft) and extending that back into the air accounting for the expected weight and drag of the plane. The descent phase often begins more than a hundred kilometers from the destination. Remember how they tell you in the cabin that the plane is starting to descent and you should put your laptop away etc? That's when the engines go to idle and if everything goes right, they won't spool up again until just dozens of second before touchdown. The goal of the entire industry is to have that happen as often as possible, on as many airports as possible.
If the plane is a bit heavier or less draggy than expected, or if the approach requires a steeper descent at some point, the airplane will calculate all that (in advance!) and let the pilot know (e.g. a DRAG REQUIRED message) and will require spoiler deployment. This is very common.
Yea that makes sense. Can't be hitting stall speed. Although maybe there's an argument for less load / wear on the turbine motor if the electric motors could be involved during landing ?
Or maybe you keep your downsized turbine motor running closer to peak efficiency even during landing and increase the mechanical energy harvesting to your APU or alternator thing or whatever to control speed and use that to charge a small supercapacitor. In the event of an aborted landing the supercapacitor could provide a boost of thrust to your electric motors. This would keep wear on the battery lower and also allow it to dump energy at its peak efficiency