Electric Aircraft interest?

bexrbetter

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#1
Modern China revolves around what is called "The 5 Year Plan", with a new one with different aims and goals implemented, wait for it ....... every 5 years!

In the previous 5 year plan, obviously among many social, industry and technology programs, pollution and congestion of the automobile was a key issue and billions of research grants were given to car manufacturers to develop electric and other 'clean' cars. (6 years later we are just seeing some and others who have failed to show what happened to their research money are seeing jail cells, but that's another story).

The current 5 year plan, instigated late last year, has two of it's categories slated for aerospace (inclusive of personal light aircraft) and new energy development so I have applied for a Grant to develop an electric aircraft. The indicators that my grant will be successful are very good, but then again, TIC - this is China where anything can happen and usually does.

Some of you may have noticed I am building an aircraft at the moment, but most of you don't know I also am involved in the beginnings of an electric car stealership of 4 brands, which has importantly given me access to all the drive systems and components, including batteries, separately. I drive and live with electric cars daily now, and have for some time, all the good and the bad that goes with them.


................


Now some of you are already thinking there's a couple of electric planes available and flying, but are they?

Would you consider a $100K - $150K (whatever) aircraft that can only for 30 to 40 minutes before requiring a 6 hour recharge? Might be ok for a training school, but I think others would grow weary of that nonsense very quickly. The others around are 'self launching' sailplanes, different, like the people who fly them.

It's very simple, batteries are heavy and bulky, it's no secret. Not just heavy, they are still heavy at the end of your trip, the weight doesn't burn off like fuel does.
What's needed for moderate stol, low stall speeds and a couple of hours flying time, is lots of wing area with low loading, something you're not going to get with a common planform.

There are a few choices for consideration ranging from lifting bodies such as the Facetmobile (a very good choice for keeping the battery mass around the CoG)..



Delta Dyke



.. to more flying wing orientated such as Northrop Avion (scaled up a bit) ..



There are other options, possibly a bi-plane might do it, but I think you get the drift, which leads me to my relevant question;

Are you willing to forgo "normal planform" (99% of the way all planes are shaped with a forward main wing and rear tail feathers), for the convenience, possible increased safety, and lowered cost of having an all electric powered aircraft?


PS: do not give me any "There's a new battery just around the corner" rubbish thanks.











 

Marty_d

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#3
Electric car stealership? Freudian slip?
I think he meant "dealership". The stealership is down the road, where they deal in second hand cars...

But seriously:

Why do you need a different planform than the regular ones? Can you not get the batteries in separate components, so you can have say 50kg of them right behind the motor (which is a lot lighter than IC), some below the pilot, and some in the wings?
 

nomadpete

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#5
I have long held a fascination for Wainfan's Facetmobile. Especially his concept for simple, cheap construction. Yes, IF I had the money, and it was available, I'd buy one. But my eccentricity is not a good market indicator. The only hope for a marketable "different" flying machine would be to do what Wainfan originally did. He built a prototype and flew it to Oshkosh, and won awards there. Instant publicity.
 

nomadpete

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#6
Electric? - as Jab has shown, the students seem to want to learn in a "proper" looking aeroplane. And I assume that the training market would be your target, with swappable batteries sitting at the "fuel shed", ready to go.
Electric seems a good proposition for short training flights. In a Jab airframe! (Note. Please activate your humour subroutine)
An advantage might be the lower noise- many strips can't allow flying too early in the day in case it wakes somebody up.

Also, training schools are more likely to appreciate the entire operating cost, and see the potential for offering cheaper hourly rates. I'm expecting the higher purchase cost is offset by cheaper fuel and engine maintenance cost over the life of the batteries and motor.
 
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aro

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#7
Conserving energy i.e. minimizing drag will be a key requirement for electric aircraft, so I would expect them to be more like gliders with high aspect ratio etc.

Look to current motor gliders to get a better idea what an electric aircraft might look like.
 

geoffreywh

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#8
Do the math, Training aircraft are doing circuits most of the time. Is there a system (batteries / motor ) than can handle that for an hour? If no, then you are wasting your time. ....I can't see many schools changing their aircraft unless the new one cheaper to run than the old one> Considerably cheaper because of the outlay..... Unless of course, they are replacing an older aircraft... The thrill of flying an electric aeroplane will wear off very quickly at $300 or so an hour....It's a shame, but it's economics. Much like our " renewable energy" Great Plan, but the numbers just don't add up.....
 

Nobody

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#10
With an aircraft one of the design considerations is keeping the CG within the limits under all loading conditions. This means that all the variable masses either close to the CG or balanced either side of it. This means that the fuel, and the passengers and their baggage all need to be lumped close together.

With a battery powered aircraft, as you note, the weight doesn't change over the curse of a flight as in a traditional aircraft as fuel is burnt off. This has positives and negatives for an electric aircraft. The negative being that you can't leave some fuel behind to take more payload but the positive is that you don't have to worry about fuel induced CofG changes. Further with an electric aircraft it is relatively easy to package the battery in multiple lumps. Multiple fuel tanks increase pilot workload and increase the risk of starvation issues so other than left/right wing tanks are often not done in small aircraft.

Based on the above I am not sure that the lifting wing shapes give you significant aerodynamic or performance benefit for an electric aircraft. They were developed to have a large volume close to the CofG but the use of electric power reduces the need for this.

When you look at the weights and sizes required a conventional layout like you are developing for your other project with an engine and batteries in front with some additional batteries behind the cockpit likely work quite well.

I think though that marketing and not aerodynamics would drive the decision. I think that a degree of Teslas success in selling electric cars has been due to the cars not looking particularly unusual. The other car makers tended to go for a very futuristic/quirky look in developing their electric cars and it scared many buyers away. I suspect that the same will apply in aircraft too.

The battery technology probably isn't there yet but it probably won't be too far away. My rough calculations indicate that to provide 50kw(about cruise power on a rotax 912s) for 2 hours you would need a battery of about 400kg.
 

bexrbetter

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#11
Thank you for your replies.


I'm surprised you have never heard the term before.


To help with your survey, I would want a conventional layout and not a space oddity. Small steps.
They are available, have fun flying for 30 - 40 minutes. You may have missed my point, I am aiming for a 2 hour duration, you can not use a normal planform for that.


. And I assume that the training market would be your target,
You assume wrong.


The thrill will wear off very quickly at $300 an hour.
Watt costs $300 per hour?


Conserving energy i.e. minimizing drag will be a key requirement for electric aircraft, so I would expect them to be more like gliders with high aspect ratio etc.

Look to current motor gliders to get a better idea what an electric aircraft might look like.
No one in my market demographic wants to own a 20 meter wing span aircraft. There are already electric motor gliders available.


Why do you need a different planform than the regular ones? Can you not get the batteries in separate components, so you can have say 50kg of them right behind the motor (which is a lot lighter than IC), some below the pilot, and some in the wings?
Every time you seperate a battery pack you include heavy cables, water cooling routes, extra structures, and extra dangers. You also increase the risk of spin and decrease recovery ability as you move weight away from the CoG in any direction other than forward.

We are talking 300+ kgs of battery here, not 50. Add to that the motor, cables and water cooling system (same as a water cooled car) so closer to 300. That's why wing area, lower loading and somewhere to put everything is needed for a small plane to run 2 hours.

Here is under the bonnet of a Siemans and a Pipistrel to get 30 to 40 minutes...





pipi power 1.jpg




With an aircraft one of the design considerations is keeping the CG within the limits under all loading conditions. This means that all the variable masses either close to the CG or balanced either side of it. This means that the fuel, and the passengers and their baggage all need to be lumped close together.
Correct, you seem to get that bit. It will take space to do it though, that's why some of the designs mentioned. If a normal planform, it will need to be a wide body to say the least, and probably bi-plane to get low wing loading, not a terrible thing and might be the answer.

I am fond of smaller Griffin concept ...





Further with an electric aircraft it is relatively easy to package the battery in multiple lumps.
That's a fallacy, there is plenty more to it as I mentioned above. For one people should understand that it's necessarily a water cooled system.



Based on the above I am not sure that the lifting wing shapes give you significant aerodynamic or performance benefit for an electric aircraft. They were developed to have a large volume close to the CofG but the use of electric power reduces the need for this.
I'll get you the numbers later. I need that space around the CoG, that's part of the point why a lifting body is ideal.


When you look at the weights and sizes required a conventional layout like you are developing for your other project with an engine and batteries in front with some additional batteries behind the cockpit likely work quite well.
As I keep saying, a normal planform and 2 hours duration doesn't work.


The battery technology probably isn't there yet but it probably won't be too far away.
There is nothing coming. BYD and Tesla, number one and two in the world for lithium battery manufacturing, along with a number of other large Chinese battery manufacturers, are gearing up and spending billions right now for the production of what we have right now. They know exactly what's available and wouldn't be doing what they are doing right now if they knew something was "just around the corner".

Even if something is suddenly discovered by accident, as all great inventions are, it's to my advantage as there will be a flood of lithium batteries on the market. - and the 'new' battery would just increase the performance of what I have anyway, Pipstrel would then have a 2 hour plane, I would have a 4 hour plane, status quo.
 
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geoffreywh

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#13
I cannot see how it could be made economically viable. The previous post says circa $300ph (under instruction) That's petrol. There's a bit in that amount for engine replacement. Electric will have to include battery replacement. ( so we remain at $250 ph hr? ) Will a 400kg? (see one of the posts) battery go 2000 recharges? ( Although the inspection cost should drop a great deal.) and if it takes a 400kg battery to get 50kw for an hour you're going to need a very light pilot an EXtremely light airframe and NO passenger or pupil. Is that a selling point?...The power content of petrol is just soooo much higher per kg. than any present battery. More is the pity. I wish you BEX all the goodwill in the world, but I think you're too early.

The previous post just popped up!...I am astonished to see a figure of $50? per hour....Really. WOW. THose batteries much be so cheap and the airframe weighs what 200kg? ( 200 battery 200 airframe and 200 pilot and px. ) for 50KW for 30 minutes...I am a sceptic
 
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SDQDI

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#19
I agree Birdseye but that biplane looks pretty nice too and would probably be more widely accepted by a broader range of us.

I have always liked different designs but a lot of people are more conservative.