The Hangar

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Federico

06:06

@TannerSwett you can run anyway, nothing prevents you from withdrawing later on.

2 hours later…

kevin

08:25

Just saw the moderator election. Coming back after gone for the entire 2019 to see what I've missed (:

8 hours later…

ymb1

16:00

WB @kevin

haven't seen anyone mention the elevator problem of the 30k airport -- how would the daily thousands on tonnes of pax/cargo make it to the top? that takes energy right? not to mention time... and changing elevators, and fainting in the elevators -- wait... pressurized elevators it is

Dan Hulme

16:19

ah, but you could run the elevators on the Swiss cablecar system, and it would be relatively cheap

ymb1

well, if it's a shallow gradient, then passengers might as well start at their destination to arrive at the departure to fly to the destination :P whatever elevator system, it's the same energy requirement moving tonnes to 30k, and it'll end up costing more energy due to the inefficiencies introduced by the number of trips

and I know you were kidding ;)

Dan Hulme

I wasn't really kidding, I think that's the best solution to the problem. Trade the energy of the arriving cargo for the energy of the departing cargo.

ymb1

but don't planes do that in descent?

Dan Hulme

airplanes have devices to dissipate energy in descent to avoid overspeed

ymb1

if the descent is started late, which it does sometimes, otherwise it's a clean decent

Dan Hulme

16:30

yeah, you're still trading energy for speed in that case

I guess the question is, what would a flat flight from one 30k airport to another look like, energy-wise

ymb1

the only loss is the engines at idle power for 12 minutes or so

Dan Hulme

if you're running the engines at cruise power during what would be the descent phase when they would be idle, your flat route is not necessarily a saving over ground-level airports

that said, I think airplane engines are sufficiently inefficient at creating height that a Swiss cablecar-like elevator and a flat route could be more efficient, even though it's not very practical

ymb1

I think I kind of get it, but then we need to consider the engines, right now they can't start in thin air and standing

that can be reengineered, but then the cruise efficiency will not be as tailored

and the tires to withstand very fast GS, faster than the Concorde/fighter-type tires

and with the reduced thrust at 30k (25% of sea level), a lot more runway will be needed to overcome the initial steep induced drag

we're talking about a brand new mode of transportation really, not jetliners as they are now

Dan Hulme

we might as well just build space elevators

ymb1

maybe steam/EM catapults like the carriers

g-training for pax

JATO (RATO really) for the planes

the latter to get the engines started after the catapult launch

reworded, I think it'll fit World Building SE

and if the inbound is a ferry flight with no payload, the pax will wait for a loaded inbound to get the cable cars working :P

but then the pax to board that loaded flight, will wait for the next loaded flight

one ferry flight ruined the project basically :P

Dan Hulme

17:12

indeed

some cablecars solve that problem by filling a ballast tank on the empty down-going car with spring water at the top of the mountain, and draining it at the bottom

but I don't think that would be an available solution at FL300