Problem with Electric Vehicles

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bifft

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I think electric could beat gas today on a self launch sailplane/non-cruising motor glider. Simpler, better restart reliability, might even be lighter if run times are kept short. Might even be lighter (haven't really run the numbers on that part).

The design goals on my napkin sketch is best climb 5 times min sink speed and enough battery for 15 minutes at full power. Even if no lift available get 60 minutes of flight out of two five minute climbs, leave 1/3 capacity in the battery to improve battery life or for emergencies.

Put some solar panels on the trailer and let it charge up on the 80-90% of days when you're not flying. Downside would be the long recharging turn-around time after that 60 minute "sled ride".
 

Aerowerx

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I think electric could beat gas today on a self launch sailplane/non-cruising motor glider. ...
Yes, but would you be trying to fly in cold weather? Probably not, since there are very few thermals in the winter anyway.

Another thought. If you could build a plane powered entirely by solar panels you would not have to worry about the cold affecting the batteries. And, as I understand it, solar panels work better when it is colder. So if you have a bright sunny day like we had here a couple weeks ago (high temp -4f), you're all set!
 

lr27

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Solar powered aircraft tend to have very light wing loadings and fly very slowly. Probably not best for soaring. I suppose if we get really good solar cells, the wing loadings can be a bit heavier, but I think there will still be a problem.

Let's say you're getting 600 watts of sunlight per square meter, which implies a fairly bright day, not terribly far north. 100 square feet would give you around 5,600 watts, or 7.5 hp. However, your solar cells might be only 20 percent efficient, and your motor might only be 90 percent. So, at the shaft, you'd only have around 1.4 hp. According to Wikipedia NASA's Pathfinder had around 790 square feet of wing*. The whole thing grossed only 560 lbs. Power output was supposed to be about 7,500 watts, or around 10 hp before inefficiencies. For something the weight of an ultralight. That's close to my estimate, but the Pathfinder was a high altitude aircraft, which I'm sure helps with the amount of sun on the wing.

Maybe if you had cells that were several times as efficient as Pathfinder's, you could power an ultralight. But that's getting close to 100 percent. And you'll have a problem if you take off after, say, 1 or 2 in the afternoon.


*Based on reported chord and span.
 

Aesquire

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On the contrary. Real, practical, solar airplanes look exactly like a high end sailplane. Or, like Solar Impulse, they are a hugely expensive stunt using NASA inspired 24/7 drone tech.

https://www.solar-flight.com

What I found interesting is to find my old acquaintance Eric Raymond online, I got Solar Impulse promos. ( I forgot his company name. He was a local hang glider pilot. We're not friends but we've met. ) I was searching first solar flight across America, and repeated news clips lied about it. Eric beat the rich team with the rich sponsors by years. Camping out by his plane, waiting for weather, it's an inspiring story, and apparently forgotten.

Torqued me right off.

Like forgetting Lindbergh ever existed and declaring Balbo the first to cross the Atlantic.

Don't believe everything you read.

Electric vehicles are waiting on batteries. They are improving. They may take a century or never equal the energy density of gasoline.

They will, for the foreseeable future, cost more even in self launch glider applications. Which are now just expensive, not impossible. That's progress.
 

Aerowerx

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Electric vehicles are waiting on batteries. They are improving. They may take a century or never equal the energy density of gasoline.

They will, for the foreseeable future, cost more even in self launch glider applications. Which are now just expensive, not impossible. That's progress.
Exactly my thoughts! An in order to equal gasoline, they will have to able to operate in the same, or most of, the environment that gasoline will.
 

Vigilant1

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On paper, for the particular requirements of airplane propulsion, a fuel cell that provides electric power to electric motors is (IMO) much more attractive than any present battery options. It could have better reliability than IC engines, much better specific energy than batteries, much faster "recharge" time than batteries (just pour in more fuel and go). But, because batteries are "good enough" for cars (whether "full electric" or plug-in hybrids), and cars will be the mass-production application that drives down costs, I don't think we'll get economical fuel cells for airplanes.
 

Topaz

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On paper, for the particular requirements of airplane propulsion, a fuel cell that provides electric power to electric motors is (IMO) much more attractive than any present battery options. It could have better reliability than IC engines, much better specific energy than batteries, much faster "recharge" time than batteries (just pour in more fuel and go). But, because batteries are "good enough" for cars (whether "full electric" or plug-in hybrids), and cars will be the mass-production application that drives down costs, I don't think we'll get economical fuel cells for airplanes.
The problem with fuel cells (and, by the way, the reason I don't think they'll catch on with cars, either) is that they throw away almost all the advantages of electric systems, while retaining some of the "issues" of electrics: Parts count is easily equal to an IC engine, still full of control and maintenance electronics, they require fuel handling and storage like an IC. Add that they're extraordinarily sensitive to fuel contamination, to a degree IC's aren't. Plus, as you note, unless they somehow get into mass production, they're ungodly expensive beasts. If you're going to accept fuel pumping and storage tanks, why not just stay with IC? It's proven, cheap, well-known, and there's still some room for improvement in IC designs.

I think airplanes (in the broadest sense) are going to go the same route as cars are: IC will hang on until hybrids start taking over for longer-range designs, with full-battery designs expanding from short-range vehicles to longer range as energy storage improves. All the major jet-engine manufacturers have hybrid jet programs, with an electric "booster" adding takeoff- and climb-power to a jet-fuel engine core that's completely optimized for cruise. I think you're going to see the first hybrid airliner prototype in the next ten years, and in-service in the next twenty. Small planes will see pure electric starting on short-range trainers and small LSA types, and expanding to longer-range aircraft as energy storage gets better. I think that, even in small aircraft, IC's will stay in play for at least another 30-50 years, at least as part of hybrid systems, unless there's some "miracle breakthrough" in electric energy storage technology.
 

BBerson

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Nothing wrong with IC. The pollutants other than CO2 have been removed.
So if the only remaining concern is excess atmospheric CO2, then make synthetic fuel using atmospheric CO2. No net CO2 gain.
 

Pops

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When we outlaw the IC engine, what are you going to do about all the people still living without electric in Appalachia, in the hollows and out the ridges miles from the grid. Do they walk or ride horses? I just looked at 47 acres that was for sale out a ridge with a small house and barn, green house and a gravity water system from a spring. Electric supplied by solar and a windmill. It is 3.5 miles from the end of the grid, and the mail box. Four farms out the ridge that is about 10 miles long. Just cost prohibited to extend the grid out the ridge. This is normal in a large part of the Appalachia. These people live on land that has been in the family for several generations, raise almost all of their food, do whatever they can do to make a little cash money by doing a little logging, selling livestock, vegetables, etc to buy the items they need and pay their taxes on the land.
We worry and help people in large cities and all over the world while turning a blind eye to a lot of our own people.
 

Topaz

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When we outlaw the IC engine, what are you going to do about all the people still living without electric in Appalachia, in the hollows and out the ridges miles from the grid...
That's about as likely to happen in the next 30-50 years as the US landing people back on the Moon or on Mars. It'll always be "20-30 years from now."
 

John.Roo

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I see two main problems with electric airplanes (cars) :)
First is in the heads of pilots - they want to have performance and range of combustion engine even of they don´t need it. I fully understand that the same is with drivers. But when I speak with drivers of electric cars and I use all arguments about length of re-charging, low range etc. they just answer that driver of electric car must change the way of thinking. The same will be with pilots of electric airplanes. "Waiting for better technology" or "waiting when batteries with 50% higher capacity are available"... this are excuses, not arguments.

Second problem is more serious... prices of electric components. Is nice to see new articles about prototypes of special high capacity cells, but I would prefer to see - we have actual existing cells for much lower prices. So "too high price for electric propulsion" is argument I accept.

Elon Musk - 2018
“We think at the cell level probably we can do better than $100/kWh maybe later this year … depending upon [stable] commodity prices…. With further improvements to the cell chemistry, the production process, and more vertical integration on the cell side, for example, integrating the production of cathode and anode materials at the Gigafactory, and improved design of the module and pack, we think long-term we can get below $100/kWh at the pack level. Which is really the key figure of merit for a car. But long-term meaning definitely less than 2 years.”

Google - today :)
"The average price a residential customer in the United States pays for electricity is 13.31 cents per kWh."

I have battery with 35 kWh capacity allowing me to fly for 2,5 hours + reserve.
https://youtu.be/y6CU8cfcYN4
If this battery will cost me 3 500 USD and energy cost per hour will be below 2.00 USD (energy for recharge x efficiency losses etc.) than will be no problem to change pilots way of thinking.
Take a look into your logbooks - what is average number of hours you fly every week / month / year? Electric propulsion will "push" you to fly much more :)

Best regards!
Martin
 

Dusan

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No problem with electric vehicles

I don't see any problems with electric vehicles. in this post: https://www.homebuiltairplanes.com/forums/showthread.php?t=28680&page=9&p=417153&viewfull=1#post417153 I've compared 2 power-plants, having similar power, electric vs internal combustion engine. The results are conclusive: designed for flying under a time threshold, an electric propulsion system weights LESS than an ICE.

The electric propulsion also is highly efficient, compared to the ICE, which narrow down to two advantages:
1. not needing so much cooling, so the aircraft can be designed much more aerodynamically, having less drag
2. high efficiency is mostly maintained at any power setting, so an aircraft that have wide range of power required(e.g. a VTOL) looks much more appealing.

Sure, the batteries specific energy, now, is puny compared to fuel, but I think it will improve over time.

This comparison was done for a feasibility study for a one person VTOL aircraft. More details here: http://aliptera.com/#ADR-1

Fore reference, I'm reproducing the graph here:
 

Aerowerx

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Getting back to my original post, is there an alternative to gasoline that can operate over the same temperature range?
 

Toobuilder

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And the ancillary question, to the point that John.Roo and myself have both made: Does there need to be?
I think the answer is generally "yes". In my neighborhood I get a seasonal temperature swing of over 100 degrees. I have launched out on cross country missions with ramp temps over 120 and less than 10. When trying to do a 1000 mile day you cant afford a lot of stops to refuel/recharge. You want to get high and fast and stay there as long as possible.
 

Aesquire

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Here it's 100 to -20, and getting high isn't as big a deal, distances are shorter.

Heck I've had years where I never hit cloudbase at less than 3500 ASL. The West coast guys were bewildered I was excited about 5000. ( not to say there were not ever higher clouds, I just missed them )

Beware excessive zeal on the Fad of Electric Everything. It is also the Fad of Fraud. Just like past Fads. Steampunk is cool, but it never happened.
 

pwood66889

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No problem with electric vehicles

<snip>

Fore reference, I'm reproducing the graph here:
Have I gotten your graph correct? To me it says that an ICE will increase only a small amount from initial weight as the time gets longer, while an electric one jumps radically.
Now, it could be restated that the ICE is much heaver than an electric motor, but the weight of the (Tank{s} and Fuel) goes up Much Faster than the (Batteries to carry the charge for that time).
An inhancement, if I may suggest, would be verticle lines where electric and ICE propultion systems have the same weight for the same operating time; a "Break Even" point.
I believe I have discussed "Mission Weight" when comparing 2- and 4-stroke engines; sorta the same deal.
Thanks for keeping me tracking!
Percy
 
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