[richardjs]

Accepting that we're just throwing out interesting-sounding ideas, I wonder if having a powered runway rail (or something of the sort) to provide takeoff power could work. With that you wouldn't have to worry about dropping anything.

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-...

[ctack]

Could use an electromagnetic rail to slowly but surely accelerate and launch it up to to cruising altitude https://en.m.wikipedia.org/wiki/Rocket_sled_launch

[scottlamb]

SupersonicScrub's comment (a sibling to yours) says that the engine can be significantly more efficient if it doesn't have to meet the power demands of take-off. Their link says "at least 30%" fuel savings on a one-hour flight (although "the fuel savings will partly come from the latest gas turbine technology"). So maybe the rail system you propose isn't such a crazy idea. Also, it's not totally different in concept from an aircraft carrier's catapult; hopefully gentler...

[magduf]

>Also, it's not totally different in concept from an aircraft carrier's catapult; hopefully gentler...

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.