21–30 of 104 posts
Earlier quoted context omitted.
The Prius is in series, or something like it.
No it’s not. The majority of power comes from the engine. It drives the electric motor mechanically, using it as a transmission. It is not just charging the battery.
1300 HP electric engine power, now that's an achievement. I do wonder if prop engines can act as "windmills" (similar to turbine engines, which often in accidents still have been found to provide a bit of hydraulic power), which means regenerative braking could be used instead of speedbrakes.
Earlier quoted context omitted.
> you're carrying all that dead weight for the rest of the flight If you're recharging the batteries for extra go-arounds during landing, they are as dead weight as the fuel you would otherwise reserve for that purpose. And if you have 30% more efficient engines, meaning less fuel and smaller engines, it's possible you could come out ahead, weight-wise. > what if you need two go-arounds I assume that a go-around requ…
> I assume that a go-around requires less sustained power output than a full climb from takeoff, No. Source 1: PE = mgh Source 2: am pilot
Also, PE = mgh is probably an not a great formula for energy cost of takeoff/go-around, as there are probably large costs it ignores (gravity loss, less efficient engine use, maybe less efficient turbines?).
For your source 2 I have no rebuttal so will have to defer to you, but would ask for an explanation.
Nothing on recharging the battery in the landing phase, so room for improvement.
Earlier quoted context omitted.
> I assume that a go-around requires less sustained power output than a full climb from takeoff, No. Source 1: PE = mgh Source 2: am pilot
You don't do a full climb after a go-around, so the heights are not equal, and the mass is less since you've expended fuel. You also retain some kinetic energy but I assume that is closer to a negligible effect. Also, PE = mgh is probably an not a great formula for energy cost of takeoff/go-around, as there are probably large costs it ignores (gravity loss, less efficient engine use, maybe less efficient turbines?).…
Earlier quoted context omitted.
> you're carrying all that dead weight for the rest of the flight If you're recharging the batteries for extra go-arounds during landing, they are as dead weight as the fuel you would otherwise reserve for that purpose. And if you have 30% more efficient engines, meaning less fuel and smaller engines, it's possible you could come out ahead, weight-wise. > what if you need two go-arounds I assume that a go-around requ…
> I assume that a go-around requires less sustained power output than a full climb from takeoff, No. Source 1: PE = mgh Source 2: am pilot
I think there are startups making a similar sort of engine for general aviation. It's good to see that there is development of the same idea for commercial aviation. This isn't like a hybrid car. It's a parallel hybrid, where the gas engine is just big enough for efficient cruise at altitude, and the electric motor/generator provides extra power for takeoff and ascent (or go-around power), and then charges slowly dur…
The fuel burn of take-off and climb substantially lightens the aircraft for cruise. Electric batteries have no such effect, you're carrying all that dead weight for the rest of the flight. This reduces the passenger or cargo capacity of the aircraft, which reduces potential revenue. And what if you need two go-arounds?
On an airplane, most of the energy in cruise is spent overcoming parasitic drag, not induced drag. It’s spent pushing the airmass out of the way as it moves forward, not creating lift to stay aloft.
For that reason, a change in weight does not significantly change cruise fuel usage.
Weight is still precious, but that’s because airplanes’ load are more often weight constrained than volume constrained, and capital and operating costs are such that you want to maximize the load.
Earlier quoted context omitted.
The fuel burn of take-off and climb substantially lightens the aircraft for cruise. Electric batteries have no such effect, you're carrying all that dead weight for the rest of the flight. This reduces the passenger or cargo capacity of the aircraft, which reduces potential revenue. And what if you need two go-arounds?
> you're carrying all that dead weight for the rest of the flight If you're recharging the batteries for extra go-arounds during landing, they are as dead weight as the fuel you would otherwise reserve for that purpose. And if you have 30% more efficient engines, meaning less fuel and smaller engines, it's possible you could come out ahead, weight-wise. > what if you need two go-arounds I assume that a go-around requ…