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Comment by cm2187 | Hacker News Reader

As a first step, they could make at least the take off and landing electric, that would help a lot with the noise and pollution around cities, i.e. where people live. I guess the batteries could be recharged during the flight for landing.

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Landings are mostly idle power until they lower landing gears in the last few miles; Take-off with fuel load is the most demanding leg and also the hardest to electrify.

...until they're not (e.g. failed landing, go-around)

Yes, my point being - there is no gain in electrifying that part and more risk in cases you mentioned.

Well yes, noise.

Hah, nope.

https://www.broward.org/Airport/Community/Documents/Stage3an...

It's also worth noting that the range of an airliner depends heavily on the fact that it becomes lighter en route through burning fuel. At takeoff, nearly half the mass of the aircraft can be fuel.

Batteries don't provide that kind of mass reduction as they discharge, which means long-range flight using only batteries as a power source is rather unlikely.

Now that electromagnetic catapults are becoming a thing, perhaps they can be adapted for airliner takeoff. One supposed benefit is the ability to adjust the acceleration profile to reduce airframe fatigue, and probably improve crew comfort at the same time. If it's smooth enough for passengers, it'd save carrying quite a bit of fuel and batteries.

I would have thought landing to be far less energy intensive (except perhaps in case of aborts, but I would imagine they're reasonably uncommon).

Although missed landings are uncommon in commercial service, every flight has to carry enough fuel for multiple missed landings, just in case.

Not sure catapults are a great idea for commercial passenger service, unless they can handle rejected takeoffs in case of other mechanical problems on the aircraft. You don't want to be catapulted off the end of the runway if you have an engine failure shortly after the start of the take-off run.

That doesn’t sound fundamentally different from having a failure on one engine sufficiently late during takeoff. Either way you probably want your other engine to have enough power to make a landing?

I remember reading one UK airline saved a huge amount of fuel just by towing their aircraft to the take off point rather than using the engines.

Probably related to Electric Ground Taxi System [0] which allows the APU(Auxiliary Power Unit, a small turbine driven generator) or potentially batteries to provide electrical power for taxiing. The APU also powers the air conditioning packs on the ground. The electric taxiing system was tested on Easyjet [1]

[0] https://en.wikipedia.org/wiki/EGTS

[1] http://aviationweek.com/commercialregiontabs-true/easyjet-te...

If you compare to hybrid cars, landing is more like braking to a stop light (unless you need to gun it again to abort the landing). Takeoff is like accelerating from a stoplight (where you need the most power). If electric could take over at any point, it would be in the steady cruise at altitude (akin to overdrive on the highway).

Going by your hybrid car analogy, electric would make most sense as a brief power boost on takeoff, allowing the aircraft to use smaller, lighter engines to cover cruising power requirements more efficiently.

Takeoff is the hardest part requiring the most power, unfortunately.

But they are also close to the main grid so could charge up a big capacitor from the mains to get a boost.

Takeoff, and landing abort. It might turn out to be economical to have hybrid engines that are fully optimized (in efficiency and in drag) for sustained climb load (or even just to cruise) that can only deliver takeoff/abort thrust using electrical assist. It could be enough to carry batteries for no more than a few minutes of assist!

I don't know though how much the efficiency of current jet engine drops off at the far ends of their throttle range.

> Takeoff is the hardest part requiring the most power, unfortunately.

So, we just need a catapult system for commercial aircraft (like used on aircraft carriers, only lower acceleration since you are doing it to reduce the amount of energy needed from the engines, not to shorten the take-off distance.)

Why not something similar to railgun but at a slower speed.

This would involve few things on the plane.

The draw back is that airports needs to install this system.

During take off, if there is a problem, the system could be stopped.

Perhaps it's not usable in this context ?

Magnetic media on the plane might be unhappy.

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