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Why battery-powered aircraft will never have significant range

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SpainCub

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Electric flight is pending a power/weight storage limitation of current batteries. Once we get beyond that, the possibility of safer flight is no longer a sci-fi discussion. One of the values is real-time monitoring of all critical components, and benchmarking MTTF a gains fleets, which is still rather limited even in Comercial aviation today. AI will play an even bigger role is improving safety by fingerprinting potential issues before they happen.

Pretty cool stuff.... it’s coming, which I know exactly when, would be vested in all those future companies.
 

tspear

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There was an interesting discussion about HP versus drag when comparing Diamond planes to Beech and Cessna on a Diamond forum.
It was pretty impressive how the slick Diamond planes use a lot less HP for the same mission. For example the DA-42 has twin 135HP engines (older model) and comes very close to matching the Baron with 300HP engines. (Baron wins down low, but by 5K the DA-42 outruns the Baron).....

How much of the analysis on energy range and requirements is based on design like the Baron, or closer to something like the Diamond?

Tim
 

sotaro

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For a battery electric or hybrid electric, I have a question about countering the wing tip vortices with wing tip propellers turning the opposite direction. What kind of forces are in play here for a 500 kg General Aviation aircraft at 100-300 km/h? Does reduction in span make adding the wing tip propellers worthwhile? It is one of the benefits of electric power I can't quantify. Great discussion.
 

henryk

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For a battery electric or hybrid electric, I have a question about countering the wing tip vortices with wing tip propellers turning the opposite direction. What kind of forces are in play here for a 500 kg General Aviation aircraft at 100-300 km/h? Does reduction in span make adding the wing tip propellers worthwhile? It is one of the benefits of electric power I can't quantify. Great discussion.
https://www.youtube.com/watch?v=zd5z0kQCNGQ

https://www.youtube.com/watch?v=jULz0afl_Ow

=hybrids...
 

pictsidhe

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Wingtop props don't eliminate drag from tips, they convert some of it into extra thrust. If you can do that twice by having winglets and tip props, even better!
 

Doggzilla

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Wingtop props don't eliminate drag from tips, they convert some of it into extra thrust. If you can do that twice by having winglets and tip props, even better!
They actually run counter to the vortex and help maintain low pressure on the wing by keeping the vortex in check. At least at low speeds when the Vortex is really bad. Which helps STOL dramatically.
 

Doggzilla

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The tip rotors in that first video seem kind of pointless since the wingtip rudders are going to handle the tip vortexes on their own.
Wingtip engines are vastly more effective. The flying pancake makes everything else look like a joke. Props running counter to the flow of the vortex.
 

Sockmonkey

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Wingtip engines are vastly more effective. The flying pancake makes everything else look like a joke. Props running counter to the flow of the vortex.
Yeah, I get what they're supposed to do but the tip rudders already do that. The pancake is a different critter and needs those props because it's such a low aspect wing.
 

Doggzilla

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Yeah, I get what they're supposed to do but the tip rudders already do that. The pancake is a different critter and needs those props because it's such a low aspect wing.
The wingtip rudders can only partially neutralize the vortex, which the wingtip engines contain the pressure a magnitude better.

The pancake requiring them doesnt change that they are more effective. A high aspect wing would also perform drastically better with wingtip engines than with rudders or winglets.

The two are not even in the same league when it comes to the level of improved performance.
 

Sockmonkey

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The wingtip rudders can only partially neutralize the vortex, which the wingtip engines contain the pressure a magnitude better.

The pancake requiring them doesnt change that they are more effective. A high aspect wing would also perform drastically better with wingtip engines than with rudders or winglets.

The two are not even in the same league when it comes to the level of improved performance.
My point is that unless it's a racer or something, the tip vortexes on a high-aspect wing aren't going to be that bad in the first place, so the tip rudders handle it well enough that we don't need to worry about it.
Now if it didn't have those rudders, then by all means stick some props on there. Electric is reliable enough to use differential thrust for steering.
 

tspear

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Random thought. Traditionally, with gas engines, energy is abundant and fairly easy to manage. Therefore, there is a greater focus on a simple airframe and engine reliability.
With electric motors, engine reliability is more "built in", but energy is much more critical. Therefore does it make sense to consider going higher and pressurize the plane so you get a higher TAS with a lower drag for electric planes? Could the new normal be, pressurized to a few PSI for electric planes?

Tim
 

pictsidhe

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Random thought. Traditionally, with gas engines, energy is abundant and fairly easy to manage. Therefore, there is a greater focus on a simple airframe and engine reliability.
With electric motors, engine reliability is more "built in", but energy is much more critical. Therefore does it make sense to consider going higher and pressurize the plane so you get a higher TAS with a lower drag for electric planes? Could the new normal be, pressurized to a few PSI for electric planes?

Tim
L/D is the same up high. There's no energy benefit to flying high. You have to fly faster to stay at best L/D at altitude. That means you need more power than down low. Electric doesn't suffer a power loss at altitude, however. So an electric plane with a reasonably healthy power surfeit for takeoff and climb should fly much higher than a non-turbo gas plane.
 

tspear

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L/D is the same up high. There's no energy benefit to flying high. You have to fly faster to stay at best L/D at altitude. That means you need more power than down low. Electric doesn't suffer a power loss at altitude, however. So an electric plane with a reasonably healthy power surfeit for takeoff and climb should fly much higher than a non-turbo gas plane.
Maybe I could have stated it better. :D
I was thinking in reverse. You want a plane to fly at set true air speed; not at a specific L/D ratio.
At 5K MSL in almost all aircraft this takes more power then at 15K or 25K. The reason is as you state; lower drag. This means less energy.

Tim
 
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