billiebob
Well-known member
Harbour Air flies Vancouver to Victoria. Perfect distance for the first commercial electric airplane.
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Electric FLIGHT is Here
- Thread starter billiebob
- Start date
Harbour Air flies Vancouver to Victoria. Perfect distance for the first commercial electric airplane.
crazysccrmd
Observer
It doesn’t seem cost effective unless they swap the entire battery pack out between trips or use a pack that can last for an entire day of operations. I’ll be interested to see how they work around the recharging vs refueling limitations.
I think you're right. They would need to be able to do a quick swap. I don't think a battery pack big enough to last the whole day would make sense, as that would mean a lot of weight - weight they could use on paying passengers and cargo.
luthj
Engineer In Residence
I look forward to aircraft that don't require complex and expensive to maintain gas turbine engines. It's going to be a while though, as battery density has a ways to go, and recharge rates with the current generation are still lacking. Though the trend may accelerate if we stop externalizing the costs of carbon fueled flight.
Some interesting numbers. Jet A has an energy density of 12500 watt-hours per kg. Typical lithium ion is about 200 watt-hours per kg.
Typical single cycle gas turbine engines are about 30% efficient, so that's about 3750 watt-hours per kg adjusted. So about 200/3750. However, the weight of the engine itself is a big deal.
A v2500A5 engine (737/A320F) weighs about 2500kg. An equivalent electric motor would weigh about 300kg. Thats 4,000kg more payload, or lighter weight. With AC each extra KG you carry means more energy to go the same distance. Its a compounding problem, so any saved weight is a big deal. So the electric option may see practical use sooner than the raw energy numbers would predict.
The other interesting aspect, is that instead of 2-4 large ducted turbofans, an electric aircraft could use numerous distributed electric ducted fans. They could be integrated into the fuselage, or spread over an unusual wing structure. These newer designs have shown promise in modeling, and could reduce the energy required for flight significantly. Since aircraft design and certification is done over the timespan of decades, its going to be 20-30 years before they reach mainstream though.
Some interesting numbers. Jet A has an energy density of 12500 watt-hours per kg. Typical lithium ion is about 200 watt-hours per kg.
Typical single cycle gas turbine engines are about 30% efficient, so that's about 3750 watt-hours per kg adjusted. So about 200/3750. However, the weight of the engine itself is a big deal.
A v2500A5 engine (737/A320F) weighs about 2500kg. An equivalent electric motor would weigh about 300kg. Thats 4,000kg more payload, or lighter weight. With AC each extra KG you carry means more energy to go the same distance. Its a compounding problem, so any saved weight is a big deal. So the electric option may see practical use sooner than the raw energy numbers would predict.
The other interesting aspect, is that instead of 2-4 large ducted turbofans, an electric aircraft could use numerous distributed electric ducted fans. They could be integrated into the fuselage, or spread over an unusual wing structure. These newer designs have shown promise in modeling, and could reduce the energy required for flight significantly. Since aircraft design and certification is done over the timespan of decades, its going to be 20-30 years before they reach mainstream though.
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shade
Well-known member
Makes sense. Just like with terrestrial vehicles, it makes sense for e-planes to start small on capabilities and build up.
Right-sizing the battery is what it's all about. Spec it for short hops with an appropriate reserve, and have a quick charge capability that can meet their turnaround time requirement. Too big of a battery would be a waste.
My thoughts exactly. Maybe they're counting on better/lighter batteries in the next two years.
shade
Well-known member
There's no need to swap the battery if it can be sufficiently charged in a short timeframe. Many lithium chemistries have very high charge acceptance rates.
luthj
Engineer In Residence
Solid electrolyte lithium chemistries currently in development can be charged from 20-90% in 45 minutes. Its going to take some more innovation, but the battery boom has already started. Massive investment in battery tech over the next 20 years will exceed investment from the previous 60 combined.
My point is that its impossible, and well within the realm of feasible in the next 30 years. The first major commercial applications will probably regional jets which fly 30-60 minutes routes 10 times a day. Prior to that will be medium sized drones in the sub 500lb range.
My point is that its impossible, and well within the realm of feasible in the next 30 years. The first major commercial applications will probably regional jets which fly 30-60 minutes routes 10 times a day. Prior to that will be medium sized drones in the sub 500lb range.
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