The age of electric flight is finally upon us

Post by Johnny555 » Fri, Jun 21, 2019, 9:11 PM UTC

newnewpdro wrote: post #198

Johnny555 wrote: post #169

Would it make sense to jettison the discharged batteries shortly after takeoff to reduce cruising weight? The "takeoff battery pack" could be in some sort of autonomous drone that pilots itself back to the airport so it could be jettisoned after reaching cruising altitude. Does weight make a significant difference once the aircraft is at cruising altitude?

Yes, planes for ages jettisoned any fuel before landing because of the weight. Keeping the landing weight down to a minimum does wonders for the airframe design. Nowadays they just do a better job of loading only the fuel necessary, and circle pointlessly to burn excess fuel before landing. It's still an issue, they just don't dump the fuel on the neighborhood below like they used to.

Post by rbanffy » Fri, Jun 21, 2019, 9:15 PM UTC

isostatic wrote: post #143

Patrick_Devine wrote: post #63

Earlier quoted context omitted.

It's a game changer for airlines such as Harbour Air in British Columbia and Mokulele Airlines in Hawaii. These are small regional airlines which operate from the water or from small airports with flight times usually less than an hour, and most of their operational expenditures are in fuel costs. Typically for these airlines you show up 15 minutes before the flight and there is no security screening, so it's very ha…

How long would recharging take?

Post by trollied » Fri, Jun 21, 2019, 9:20 PM UTC

upofadown wrote: post #171

marvin wrote: post #20

I fly gliders. Absolutely can't wait until my local club finally decides to get an electric single-seat self-launching glider, preferably with enough endurance to do some additional tens of kilometers after the launch, in order to avoid landing out if the weather dies out. It's a gamechanger with regards to both costs and convenience. No towplane, towplane pilot, no outlandings.

Self launching on batteries means carrying around a fair bit of dead battery weight for the entire flight. Electric sustainers (can't take off but can stay up) are pretty interesting because gliders take hardly any power to fly level. Example: * http://front-electric-sustainer.com All this electric vehicle technology works really well for electric glider winches. You can get a whole lot of peak power off of a battery…

Post by dreamcompiler » Fri, Jun 21, 2019, 9:31 PM UTC

jacquesm wrote: post #208

dreamcompiler wrote: post #201

I know nothing about Eviation other than what this article says. They're claiming 650 miles of range with nine passengers on batteries, and to that I will not say I'm merely skeptical. I'm saying they are flat-out liars selling bullshit, and I'll stake my engineering reputation on that statement.

> I'll stake my engineering reputation on that statement Such forceful claims should not be made anonymously. I'm with you on the claim itself but feel that if you want to make that statement and stand by it that you should do so with your name and 'engineering reputation' attached to the claim itself.

Post by namirez » Fri, Jun 21, 2019, 9:47 PM UTC

waterhouse wrote: post #209

FabHK wrote: post #197

Earlier quoted context omitted.

> > improved modern materials means you can just have most of your take-off mass be battery, compensating for the poorer specific energy > Again, this can be done for any aircraft, not just the electric ones. Not only that: you burn the fuel, so for the second half of the flight you only need to carry half the fuel. But you have to carry the full battery mass (modulo E=mc^2) all the way.

Dumb idea: If the weight of the batteries is significant, then dump out the empty ones with parachutes partway through the flight?