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Why battery-powered aircraft will never have significant range

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Doggzilla

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A 10 fold improvement sounds like BS to me.
At like 300 degrees its possible. Clearly that would be useless in real life.

What they announced is the ability to use Flouride at near room temperature.

The hot version is already proven, but clearly useless in its original form.
 

Doggzilla

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It's probably one of those percentage things that's "technically" true but is actually way less than they make it sound.
They said they don't even have it working yet so I'm not holding my breath.
It clearly says they have a working prototype.

"When used in a prototype battery composed of copper, lanthanum, and fluorine, the new battery was able to be discharged and recharged at room temperature."
 

pictsidhe

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At like 300 degrees its possible. Clearly that would be useless in real life.

What they announced is the ability to use Flouride at near room temperature.

The hot version is already proven, but clearly useless in its original form.
10x the capacity of lithium, but at 300F? Yeah, right...
 

Sockmonkey

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It clearly says they have a working prototype.

"When used in a prototype battery composed of copper, lanthanum, and fluorine, the new battery was able to be discharged and recharged at room temperature."
They mentioned that the anodes and cathodes get eaten away quickly, which means it's still in the category of "impressive thing in the lab that's not at all practical in the real world" so we shouldn't get excited yet.
 

Bigshu

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So at time 0 there is no batteries, no fuel, the weight of the electric is about 15Kg, the ICE is 66Kg. Comparing them at 40KW, the red and blue line, the electric is less until about 20 minutes. At 20KW the electric weight stays lower until about 40 minutes, yellow and green line.

As I mentioned before, this is relevant a small aircraft I'm doing the concept on, 40KW would be needed to hover and 20KW for cruise. What I'm saying, is that under a certain range, all electric propulsion would weight less than an internal combustion.
So what kind of range are you positing for those flight durations? What kind of range are you thinking for VTOL takeoff and land, with cruise in the middle?
 

Dusan

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The VTOL flight portion is short (maybe 2-3 minutes) and range depends how "clean" the aerodynamics is. If the aircraft can stay in the air for 40 minutes and consume 20KW in cruise and still get to 110kts, that means range would be about 70nm. If not, range will be shorter. Anyway range is highly dependent on L/D, efficiency and weight ratio. Look for modified Breguet range equation.
 

Speedboat100

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Don is correct. Your statements are conflicting.

Your previous statement agreed with him when you said a given L/D was faster at higher altitude, while using the same power setting.

Now you're saying it requires more power. It does not. The additional speed is allowed by the reduction in drag by the reduced air density.

No additional power is required to take advantage of that.

But you need much higher pitched propeller in high speed...or double the rpm.
 

Speedboat100

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I think the electric flying is still in its infancy.

luciole.jpg

Above Luciole MC 30.

Electric aircraft development of the basic design, first flown on 1 August 2011. Powered by 26 hp (19 kW) electric motor running from a 4.7-kWh Kokam battery. The aircraft weighs 113 kg (249 lb) empty and has a 55 minute endurance on a charge. The aircraft has achieved a top speed of 220 km/h (137 mph).[10]
 
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henryk

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Speedboat100

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Years ago Chevron renamed itself the Energy Company. They tried to distance themselves from being oil only. As part of this effort, they bought a couple of solar companies, a battery company...
I have no idea of the success or if it persisted.
But the basic concept is the same to me, stop thinking about batteries per se, or gas engines... They all are part of an energy storage system.
So it does not matter if it is LI, or gas, or Jet-A. What matters is I can get more, makes the plane useful, and is not made from unobtanium.

Tim

Aaaahh....the famous unobtainium card again !

The problem is speed. Solar powered aircraft will always remain slow. That too is simple physics.

If we look up the state of the art, you're talking about cruise speeds in the 30-35 mph range give or take. Those are aircraft with solar cells of around 20% efficiency. Theoretical PV efficiency is on the order of 75% efficiency. Since power required goes up with the cube of the speed, even a theoretically perfect solar aircraft will cruise at a modest 45-50 mph.





I picked the "never" for a good reason, next to being sure to lead to a lot of discussion. The point is that we are up to fundamental limits, not some artificial barrier in progress. Over the last 30 years we have only seen a two-fold increase in energy density in batteries, though they've gotten much more practical. We are fairly close to the theoretical limitations and those we will never surpass. Just like a prop can't be >100% efficient, a piston engine can't exceed 60-something percent thermal efficiency etc.

If somebody claims doubling the efficiency of a prop or a combustion engine, such claims are quickly refuted to the mad-house. Yet, there is widespread belief in the enormous potential increase in battery energy density. That hasn't happened anywhere to the extent most people think (two-fold since the cold war roughly) and we are hitting solid physical barriers very soon.



Don't get me wrong. Battery powered and solar panel powered aircraft are practical and feasible today and I certainly believe they're the future. Just not for going places unless you consider a FAR103 design adequate.
I recall Helios went nearly 300 km/h at 98 000 ft..some call it fast.

But add 60% battery power to it and you get high fast.
 

Speedboat100

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Can we define significant range ?

I say 300 km is already significant.

I suggest that the GosHawk project be completed, flown, and evaluated.


BJC
It adds up 363 km range if they are correct.

--

Eraole seem to have become a biplane ( here still a two wing ): Greener skies: Frenchman prepares for history-making zero-carbon Atlantic flight


history Funk has lotsa good ideas.

Wright bros infact also invented the first real biplane as well: 1910 Wright Model R
 
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