But I do wonder how much power is actually expended at takeoff versus climbing or cruising flight. According to [1], only ~19% is used for both takeoff and climb, so electrifying the runway to save the fraction of the 19% used while in contact with the ground is probably not worth it.
[1] https://aviation.stackexchange.com/questions/47262/how-much-...
Nah. If someone can't handle a few g's in takeoff, maybe they shouldn't be flying, and should should stay home, or maybe in a nursing home. I know it sounds mean, but seriously, think about it: aircraft transport isn't always comfortable. Turbulence happens, and it can be extremely rough at times, even injuring people severely if they're not belted in. If someone is too frail to handle being launched by an aircraft carrier catapult (which, remember, also launch those big AWACS planes, not just small fighter jets), then they're not suited for handling turbulence either.
Also, don't forget, the latest generation of catapult technology is actually pretty gentle. The USS Ford's "EMALS" catapults are electromagnetic, rather than steam, and one of the big stated benefits of this is that it's gentler on the airframes than the old steam catapults. It's still going to subject the pilots/passengers to several g's, but probably lower peak acceleration than the older technology did.
Maximum power requirements come from take-off and climb-out, so the engine size is designed around the max take-off power. This means that the engine is over-designed and less-efficient for the majority of the flight.
By implementing a hybrid engine, the gas-powered component and the electric powered component work together to provide take-off power requirements. By the time the aircraft reaches cruising altitude, the batteries are dead, and the gas-powered component works alone. This allows the engine to be designed for the cruise power requirements, which results in a much more efficient engine. UTC is currently experimenting with this concept.
https://www.flightglobal.com/news/articles/utc-to-test-hybri...
Yes it's not carbon neutral, but it's a step in the right direction.
However I also wonder why, if electric motors are a solution here, there hasn't been a comparable fuel-powered extra-takeoff-engine. Why would this not have the same benefits? Or are extra engines simply too complicated mechanically unless they are motors?
(The liked article is about modifying a Dash 8, which is a turboprop, and perhaps it's easy to have oversize propellers for takeoff, and just connect a motor to the same gearbox.)
Military aviation has dealt with this in various ways:
1. Carried aloft by a larger plane
2. Towed aloft be multiple other planes
3. Jet assisted takeoff
4. catapults
5. drop tanks
6. mid-air refueling
That seems quite dangerous - to both the aircraft and everyone onboard, as well as to anyone on the ground in the path of this cable.
Simply put, that's just not how aviation works.
Mechanical failures aren't uncommon in aviation, but for an aircraft to not be able to divert and return to the ground, a lot has to go wrong all at once. It's infinitesimally rare for all systems to fail at once on an airliner. There simply isn't a problem of airliners dropping out of the sky, ever. They're incredibly robust machines.
However, with your idea, we'd be relying on a single system to prevent catastrophic failure. That's a massive step backwards for aviation.
That doesn't even begin covering the problems with delivering enough electricity over this cable to power an airliner at takeoff... That cable would need to be a very thick gauge of wire and very heavy - causing all sorts of it's own problems.
It's actually an interesting supposition, because whether it's gasoline or electric, it should be cheaper and more reliable to run a ground operation than to pack fuel that is expelled before anything meaningful has happened.
But having also launched from a carrier myself, I wouldnt want that g force everytime I fly commercially.
If I was a carrier pilot, I doubt I'd ever get used to that!
Yes, but the reason they're used is because it's infeasible or too expensive to build an aircraft carrier long enough to have jets reliably take off from them without this extra boost. Even so, those catapults are fairly short: notice they're only a fraction of the length of the carrier.
They're not used in regular airports because they're not absolutely necessary, the way they are on aircraft carriers. It's more expense, and planes can do without them. However, there's a cost to this: the planes need bigger engines and more fuel to take off reliably. And bigger engines are less efficient overall (as in cruising). So there would be a significant fuel savings if you could count on having catapults on the ground to help get the plane to takeoff speed: you could downsize the engines, and carry less fuel, saving a lot of money overall per flight (not to mention all the carbon pollution).
Finally, the extra g-forces shouldn't be a big deal. There's high g-forces in a carrier launch because the catapults are very short. And until recently, they were steam powered. This needn't be the case with commercial aviation: they can use modern electromagnetic launchers, and they can make the catapults very long (as long as much of the runway), to have lower peak acceleration. Basically, the planes and passengers would not need to experience higher g-forces than they already do; they'd just be getting them from the catapult instead of solely from the engines.
https://en.m.wikipedia.org/wiki/Space_fountain
https://en.m.wikipedia.org/wiki/Cloud_Nine_(tensegrity_spher...
Regardless of the specifics, it's obvious that any of these schemes is a logistical and technical nightmare compared to "taxi up to the terminal, plug in the refueling hose while people and cargo are loaded onto the plane." It's unlikely that the private sector will be too enthusiastic about investing in anything like this without heavy incentives.
Ideally when we have kerosene based fuel cells we could have small electic aeroplanes that will be much easier to control, and would allow more frequent direct flights, instead of having to collect 100s of people together make them wait several hours, and drop them at an inconvenient location.