Electric Powered Aircraft
This is all very well, but what will the turn round time be to recharge a 600 mile range battery to allow it to fly back?
I might just be confused, but it seems as though this 'electric' plane is powered by a gas turbine which drives the main pusher propeller and runs a generator that powers two wing tip electric motors; that's how they can achieve a 650 mile range - it's not running of batteries. How is this an 'electric' plane? What about the loss of efficiency every time there is a power conversion step? Am I missing something here?
I might just be confused, but it seems as though this 'electric' plane is powered by a gas turbine which drives the main pusher propeller and runs a generator that powers two wing tip electric motors; that's how they can achieve a 650 mile range - it's not running of batteries. How is this an 'electric' plane? What about the loss of efficiency every time there is a power conversion step? Am I missing something here?
The linked article's final paragraph mentions a different aircraft (or different optional hybrid power system) - EcoPulse. In passing, it should be noted that many large ships (E.G. RMS Queen Mary 2) now use "distributed power" - diesel or turbine-powered generators produce electric power to drive the actual electric motors attached to the props.
See: https://en.wikipedia.org/wiki/Integr...ric_propulsion
As to the change to a tailwheel - probably to protect the pusher-prop (as noted, it was a bit exposed to a prop-strike in the tricycle configuration).
But for those wondering about where the nose wheel would have fitted in the original: Pilots have been stepping over a hump between the cockpit seats since the DC-3 and B-17 - it's called a control pedestal. Check that original shiny-floor mockup and you'll see the nose-wheel would have retracted right between the pilots. And in an electric plane, the throttles are probably simple rheostats - the pedestal will be mostly empty space with minimal levers and such inside. Tuck the wheel right in there.
See: https://en.wikipedia.org/wiki/Integr...ric_propulsion
As to the change to a tailwheel - probably to protect the pusher-prop (as noted, it was a bit exposed to a prop-strike in the tricycle configuration).
But for those wondering about where the nose wheel would have fitted in the original: Pilots have been stepping over a hump between the cockpit seats since the DC-3 and B-17 - it's called a control pedestal. Check that original shiny-floor mockup and you'll see the nose-wheel would have retracted right between the pilots. And in an electric plane, the throttles are probably simple rheostats - the pedestal will be mostly empty space with minimal levers and such inside. Tuck the wheel right in there.
Color me skeptical. Here are some VERY rough numbers; please feel free to correct any errors of bad assumptions.
I am comparing the weight of energy for a Cessna Grand Caravan and the electric plane, simply because they are about the same size and carry approximately the same number of passengers.
1) The energy density of kerosene is 39.5 kw-hr/gallon
2) The Caravan consumes in the range of 75 gallons (550#)/hour in cruise. For a 540 mile trip this is approximately 1650# or 8850 kw-hr of energy.
3) The energy density of a Lithium battery is maximally about 250 wh/kg, so let's give the electric a generous 400 wh/kg.
4) Let's give the electric machine another boost and call the efficiency of the turbo-prop 30% and the electric 100%.
5) With these assumption the electric will need 2655 kw-hr of stored energy and will arrive with a flat battery and no reserve.
6) At 0.4 kw-hr/kg the battery will weigh 6600 kg.
Doesn't look doable to me
I am comparing the weight of energy for a Cessna Grand Caravan and the electric plane, simply because they are about the same size and carry approximately the same number of passengers.
1) The energy density of kerosene is 39.5 kw-hr/gallon
2) The Caravan consumes in the range of 75 gallons (550#)/hour in cruise. For a 540 mile trip this is approximately 1650# or 8850 kw-hr of energy.
3) The energy density of a Lithium battery is maximally about 250 wh/kg, so let's give the electric a generous 400 wh/kg.
4) Let's give the electric machine another boost and call the efficiency of the turbo-prop 30% and the electric 100%.
5) With these assumption the electric will need 2655 kw-hr of stored energy and will arrive with a flat battery and no reserve.
6) At 0.4 kw-hr/kg the battery will weigh 6600 kg.
Doesn't look doable to me
Last edited by Winemaker; 22nd Jun 2019 at 23:42.
https://www.dw.com/en/ampaire-test-f...ane/a-49098126
Looks like they put an electric unit in the rear, while keeping the recip in the front- and STILL needed a pod to house the batteries.
Hardly ground-breaking.
It's all vapour-ware until battery technology makes another quantum leap. It will happen, but not as soon as the plethora of "paper aeroplane" companies suggest.
Join Date: Nov 2000
Posts: 645
Likes: 0
Received 0 Likes
on
0 Posts
Batteries as we know them are certainly not weight efficient enough for aviation use and won't be for tens of years to come. Hydrogen has volume and storage issues. It looks like the only high capacity electrical power source for aircraft might be nuclear fuel from a pure technical standpoint. I'd stick to Kerosene.
Join Date: Jul 2007
Location: Auckland, NZ
Age: 79
Posts: 722
Likes: 0
Received 0 Likes
on
0 Posts
The company said this is a "parallel hybrid," meaning the internal combustion engine and electric motor work to optimize power output as the plane flies.
https://www.dw.com/en/ampaire-test-f...ane/a-49098126
Looks like they put an electric unit in the rear, while keeping the recip in the front- and STILL needed a pod to house the batteries.
https://www.dw.com/en/ampaire-test-f...ane/a-49098126
Looks like they put an electric unit in the rear, while keeping the recip in the front- and STILL needed a pod to house the batteries.
In land transport, with weight not being a critical factor and constant variation of speed to charge the battery, I can see this might be a win, with a smaller ICE running more of the time in its most efficient regime. I would be very sceptical about an aviation application, but I know nothing, and it would presumably take some fairly serious analysis to see if the added complexity was worth the gains. Does anyone have information?
UTC is betting on an electric future and is building a flying demonstrator. They are not playing with small airframes but are converting a Dash 8.
The hybrid electric is a good start to an electric future. There will be much experience gained and a potentially viable hybrid aircraft to boot.
Besides building a flying demonstrator, they are also building a lab to support future development. Construction has already started.
Besides building a flying demonstrator, they are also building a lab to support future development. Construction has already started.
Join Date: May 2003
Location: KGRB, but on the road about 1/2 the time.
Age: 61
Posts: 622
Likes: 0
Received 0 Likes
on
0 Posts
The "Alice" has been ordered in double-digit numbers by Cape Air, a US airline that flies small planes on short routes.
https://www.capeair.com/#/availability
Apparently, they are now flying to Australia...."Billings to Sydney" (dry humour)...
https://www.capeair.com/#/availability
Apparently, they are now flying to Australia...."Billings to Sydney" (dry humour)...
Join Date: Mar 2010
Location: Often in Jersey, but mainly in the past.
Age: 79
Posts: 7,808
Received 135 Likes
on
63 Posts
As an all-electric car owner, I'm happy after a full charge from the mains electricity gives me 70 miles range ... at c. 30 mph.
The basic physics of batteries have a long way to go, IMO.
There's a lot of fantasy in these expositions.
The basic physics of batteries have a long way to go, IMO.
There's a lot of fantasy in these expositions.
Another one bites the dust:
https://www.seattletimes.com/busines...s-out-of-cash/
https://www.seattletimes.com/busines...s-out-of-cash/
Zunum, the Bothell-based startup developing a small hybrid-electric airplane, has run out of cash, and much of the operation has collapsed.The company promised to develop a family of small jets to serve lucrative short-hop routes with on-demand air-taxi services. A graphic produced by the company showed three different electric aircraft flying over Seattle: a 10-seat plane; a 50-seat plane; and a 100-seat airliner.The credibility of the company’s Silicon Valley-style pitch for a technology shift that would transform aviation was boosted by investments from Boeing and JetBlue. But unless new investors step forward, that fanciful dream is dead.