Why Gas Engines Are Far From Dead - Biggest EV Problems

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cblink.007

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Gas engines ARE dead, a tesla SEDAN will take just about anything but a top fuel dragster at the lights.
Same with electric bikes,nothing that burns fuel can stay with one.
An academic discusion of the energy density of varios storage types is of course still valid,though
the rate at which newer more modern energy storage means are advancing tells the tale to come,and that soon.
"The future is here now,its just not evenly distributed"
Brushless electric motor and controller technology and performance are certainly up to the task of the light GA mission set. But the state of the art in battery/energy storage simply is not there. Not yet...at least not for sustained operations (ie 1 to 3 hours endurance).

The day will come when we have a light GA bird that can perform at the same level as a Cirrus SR22 or similar, range in all, but the price point needs to be on par, if not outright below current GA prices. Also, the aircraft battery systems must have fast recharge capability.

The moment an electric power solution hits the market that has power, endurance and significant affordability, will be the moment that the days of the fuel-burning powerplant become limited.
 

stanislavz

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But the state of the art in battery/energy storage simply is not there. Not yet...at least not for sustained operations (ie 1 to 3 hours endurance).
I have run some numbers in past - electric is on pair with two strokers. Due to similar mission targets - limited range due to ears fatigue/small cockpit fatigue. And fuel burn rate of two stroke rarely calls for longer thant 1 hrs mission. So for me - yes, for small/nice one/two seater with primary mission to go circles/loops around airport. But something faster, than sky pup or similars.. Because - 20kw power motor + 20kw/h batter is only ~5-8 kg less than 40kw electric motor + 20 kw/h battery. And draining all battry juice in 20-30 minutes ok on battery of any decent chemistry.

And you can go for 60kw motor with same battery setup too.. 20kwh of battery weight ~ 100 kg / 220 lbs..
 

cblink.007

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I have run some numbers in past - electric is on pair with two strokers. Due to similar mission targets - limited range due to ears fatigue/small cockpit fatigue. And fuel burn rate of two stroke rarely calls for longer thant 1 hrs mission. So for me - yes, for small/nice one/two seater with primary mission to go circles/loops around airport. But something faster, than sky pup or similars.. Because - 20kw power motor + 20kw/h batter is only ~5-8 kg less than 40kw electric motor + 20 kw/h battery. And draining all battry juice in 20-30 minutes ok on battery of any decent chemistry.

And you can go for 60kw motor with same battery setup too.. 20kwh of battery weight ~ 100 kg / 220 lbs..
I can absolutely agree with your perspective. I should have made mention of the 2 cycle community, so I apologize!

In all honesty, my dream would be to electrify my 2-seat design...or at least hybridize it! My all wing bird has a 'cavernous' area in the centerbody on both sides of the cockpit that can easily accomodate a sizable bank of li-po batteries (once ruggedized, of course)!

It is a neat new branch of the art...and I strongly believe our community rightfully belongs on the forefront of it!
 

stanislavz

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In all honesty, my dream would be to electrify my 2-seat design...or at least hybridize it! My all wing bird has a 'cavernous' area in the centerbody on both sides of the cockpit that can easily accomodate a sizable bank of li-po batteries (once ruggedized, of course)!
My nap-sketch was redone many times - but best of the buck was looked like this: tractor or pull configuration, twin motor, with batteries at wingtips, wing tips with size to support battery weight.

for ul class in eu - we want/have 40-50% of airframe to be battery at least for mtow 450kg - 200 kg useful load, 250kg engine and airframe 100 kg airframe and 150 all electric stuff..

And if done classic way - 200 kg of useful load + 150 kg of motor/batteries in fuselage - it is hard way to make with 100 kg for airframe.

BUT! if we put batteries in wingtips, motors in simpler nacelles - we have doable solution We have left only 200 kg of useful load to deal with. And we go with twin boom - we are even splitting airframe weight. And much safer. If on motor/battery pack would catch fire - we will end with this :

1590588590623.png



Ugly - but will take you home safely :)

On construction side - making two smaller composite airplanes is faster and cheaper than one big.. For central section - you would weld some steel cage still :)

And one small + for twin or 4 motor solution - for 12-15kw of power, large pancake motor is totally doable in cheap china way with only air-cooling. Anything more will call for water cooling..
 

Dan Thomas

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Batteries in the wingtips isn't a good idea as far as aircraft stability is concerned. If the airplane stalls and starts into a spin, that rotating mass so far from the center of rotation makes it hard to stop the spin. It's one reason why fuel tanks in the wings are near the fuselage. Tip tanks are normally quite small.
 

Topaz

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Batteries in the wingtips isn't a good idea as far as aircraft stability is concerned. If the airplane stalls and starts into a spin, that rotating mass so far from the center of rotation makes it hard to stop the spin. It's one reason why fuel tanks in the wings are near the fuselage. Tip tanks are normally quite small.
Not to mention slow the roll rate and require larger ailerons (and therefore also rudder) for adequate lateral control. There are very good reasons that small-plane designs tend to concentrate masses near the center of gravity, and it's not only the CG range.
 

stanislavz

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Prove me wrong - Pazmany pl2 have fuel in wing tip tanks only. And was far from slow aircraft..
 

dog

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Dec 29, 2019
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Batteries in the wingtips isn't a good idea as far as aircraft stability is concerned. If the airplane stalls and starts into a spin, that rotating mass so far from the center of rotation makes it hard to stop the spin. It's one reason why fuel tanks in the wings are near the fuselage. Tip tanks are normally quite small.
Good point,that you have made concerning mass
placed at the exremities,including aft.
So ,as the flexibility is there,put the battery under
the cabin ,one, or wrap the whole fueselage and
get the cg,exactly where it helps stability and control.
And ya they still catch on fire,mainly due to dendrite growth of lithium crystals,though there is
any number of good ideas moving into production
that dramaticaly reduce that.
The full scope of current battery research is HUGE,
horibly techneckly complicated, and fraut with every kind of wild speculation,wishfull thinking,outright fraud, and pile of excellent work.
Its not my field but I lumber along reading as much as I can.
There are significantly better batteries in prouction
and use that have not made it in the mass market,presumably because of cost,which should
be less of an issue for aiviation, given the prices
charged for everything else that makes an airframe, before the fuel costs
 

cblink.007

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Messages
207
Location
Texas, USA
There are significantly better batteries in prouction
and use that have not made it in the mass market,presumably because of cost,which should
be less of an issue for aiviation, given the prices
charged for everything else that makes an airframe, before the fuel costs
Just because this is aviation doesn't necessarily mean that we can absorb any high cost...

A new, electric light GA bird must, at an absolute minimum, match the capability, performance and utility of either a Cessna 172, Piper PA28, Cirrus SR22 or equivalent...AND be less expensive to purchase, operate and maintain if it is to be successful, and to have ANY chance of resurrecting private civil aviation as we know it.

A brand-new Piper Cherokee Arrow starts at well over $320,000. Wrong answer...

...as a community, we have A LOT of work ahead. And, it will be up to us to innovate these solutions!
 

BJC

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A new, electric light GA bird must, at an absolute minimum, match the capability, performance and utility of either a Cessna 172, Piper PA28, Cirrus SR22 or equivalent...AND be less expensive to purchase, operate and maintain if it is to be successful, and to have ANY chance of resurrecting private civil aviation as we know it.
I believe that a two seat electric airplane that can do both touch-and-go circuits for an hour, as well as takeoff, climb to 3,000 feet, cruise for an hour, descend and land, while still having enough energy for 1/2 hour endurance and one go-around, will find a sizable market if the price is right. The right price will be less than a professionally constructed RV-7.

It will need to have a battery that will be usable for enough flight cycles that replacement cost is reasonable, and it will need to be rechargeable with low amperage, 120 volt, single phase electric service common in hangars at public airports.

I don’t expect such an airplane to be commercially available within the next few years. And yes, I have looked at the Pipistrel Alpha Trainer and concluded that it does not meet this criteria.


BJC
 

dog

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Dec 29, 2019
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294
Just because this is aviation doesn't necessarily mean that we can absorb any high cost...

Because its aviation we ARE absorbing high costs
,training,fuel,insurance,technical expertise,parts,insruments,more training,"fees",more fees.
So returne serv then, puzzle me this affordable
cheap,easy,aiviation that you alude to.
And I mentioned money just to stur the pot.
What up?
 

cblink.007

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Messages
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Texas, USA
I wasn't attacking you. I was only clarifying. You were correct to bring the money matter to the equation!

Yes, aviation is expensive. It is not easy. And no, electric is not, and never will be the unicorn to make it "cheap". I wish it was. However, it will point our community to more affordability and sustainability, which is what we need.

That is what's up, and I am sure you will agree!
 

stanislavz

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Good point,that you have made concerning mass
placed at the exremities,including aft.
So ,as the flexibility is there,put the battery under
the cabin ,one, or wrap the whole fueselage and
get the cg,exactly where it helps stability and control.
Rutan boomerang ? Or rc tug for sailplane...
 

SlowFlight

Member
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Dec 31, 2016
Messages
6
Location
Alaska
I believe that a two seat electric airplane that can do both touch-and-go circuits for an hour, as well as takeoff, climb to 3,000 feet, cruise for an hour, descend and land, while still having enough energy for 1/2 hour endurance and one go-around, will find a sizable market if the price is right. The right price will be less than a professionally constructed RV-7.

It will need to have a battery that will be usable for enough flight cycles that replacement cost is reasonable, and it will need to be rechargeable with low amperage, 120 volt, single phase electric service common in hangars at public airports.

I don’t expect such an airplane to be commercially available within the next few years. And yes, I have looked at the Pipistrel Alpha Trainer and concluded that it does not meet this criteria.


BJC
Thank you for all of your input over the years. I have learned much, but not enough.
These are my thoughts on Power from a wall outlet.
120v 15amp=1830 watts, charge loss efficiency slow charge maybe 10%, 1647watts, throw in guess for take off high discharge loss additional 5%, 1564watts, then a 95% efficient motor 1486 watts, HP=746watts=1.99hp per hour of charging. 24hours might produce 48hp/hour, per day charging, though not all discharged in an hour. The high discharge rate might reduce useful power considerably through battery heat.

C152, say guess 95 hp, 71kw(hr), Take off climb to 3k at 750fpm, 5 mins = 6kw, almost double that for a high discharge rate, could be 10kw. That would be 7 hours of charging by itself. 1/2 hr reserve at 75% = 75hp = 38hrs of charging. Not so frequent flying. Going to 240v and higher amperage would help a bit. I think the electrical hookup costs are going to be less than the electric plane.
 

BJC

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These are my thoughts on Power from a wall outlet.
I should have made it clear that the usage of the airplane I was thinking of would be a single weekend flight.

For those of us who live on an airport and or own our own hangars, higher energy sources typically are available, and would allow more rapid recharging.


BJC
 
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