Electriflying

wrote:
vaughn wrote:

wrote in message
...

transportation, Noun

1. The action of transporting someone or something or the process of
being transported.

transport, Verb

1. To carry from one place to another; convey.


The word "transportation" implies nothing about either the purpose
or the distance of the movement. It just means movement.

If I fly 25 miles to get a hamburger, the airplane provided the
transportation.



OK. This conversation has descended to idiocy.

See you next thread perhaps.

Vaughn

Sorry if my use of English words as defined by the dictionary offends
you somehow.

I think perhaps he meant to say it had descended to pedantry, ergo idiotic.

In article ,
"vaughn" wrote:

wrote in message
...
How many light planes are actually used for transportation?

All of them that fly unless they are remotely controlled.

The trip may be as short as 3 turns around the pattern to maintain
currency,
but a person is still being moved.

Sorry, but that's stretching a point beyond nonsense. You could also argue
that a pogo stick is a transportation device, but few would take you
seriously.
"Three turns around the pattern" may actually be either recreation or
training,
but hardly transportation. Most light planes are used for training and
recreation, not transportation. Regardless of the owner's intentions when
they
buy them, few light planes are actually used for serious transportation.

This thread started with a post about a 2-place training aircraft with a 90-
minute endurance. Fact is, that plane (if it really exists) could handle
many,
(possibly most) of the missions I see flown out of my local airport. If
available as a rental, it could handle about 70% of my own flights.

Vaughn

That all depends on turnaround time. If it takes 8 to 12 hours to
recharge the batteries, the plane will be sitting idle for most of the
operating day -- not a good return on investment!

Orval Fairbairn wrote:
In article ,
"vaughn" wrote:

wrote in message
...
How many light planes are actually used for transportation?

All of them that fly unless they are remotely controlled.

The trip may be as short as 3 turns around the pattern to maintain
currency,
but a person is still being moved.

Sorry, but that's stretching a point beyond nonsense. You could also argue
that a pogo stick is a transportation device, but few would take you
seriously.
"Three turns around the pattern" may actually be either recreation or
training,
but hardly transportation. Most light planes are used for training and
recreation, not transportation. Regardless of the owner's intentions when
they
buy them, few light planes are actually used for serious transportation.

This thread started with a post about a 2-place training aircraft with a 90-
minute endurance. Fact is, that plane (if it really exists) could handle
many,
(possibly most) of the missions I see flown out of my local airport. If
available as a rental, it could handle about 70% of my own flights.

Vaughn

That all depends on turnaround time. If it takes 8 to 12 hours to
recharge the batteries, the plane will be sitting idle for most of the
operating day -- not a good return on investment!

The current crop of electric cars "quick charge" times run from about
3 hours to 6 hours with 240V/48A service and 2 to 3 times that for
standard 110V service.

So allowing 1.5 hours to get the airplane in the air, do training, get
the airplane back on the ground, do the paperwork, hook up to the charging
station, then 4 hours of charge, you could get 2 flights per day in an
eleven hour day.

Cut the charge time in half to 2 hours and you can get 3 flights per day.


--
Jim Pennino

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"Orval Fairbairn" wrote in message
news
That all depends on turnaround time. If it takes 8 to 12 hours to
recharge the batteries, the plane will be sitting idle for most of the
operating day -- not a good return on investment!

Yep. I actually agree 100%. We discussed that very point a few days ago.
That, along with the amortized hourly price of battery use are potential deal
killers, and are up to the manufacturers to solve if electric planes are ever to
make a dent in the training market.

Vaughn

On Jun 22, 10:17*am, Gatt wrote:
A few years ago when people were discussing the possibility of
electric-powered flight, you'd get hacked on pretty hard for
suggesting such a thing would be practical or possible in our
lifetime. Obviously if you knew anything about physics or electrical
engineering, why, you'd know it was totally impossible.

Buddy of mine has a Tesla. It'll make Seattle on a charge, he says.
You couldn't have done that with an electric car even a few years ago.
It's amazing what they've been able to do, and it only gets better.

Curt

On 2011-06-27, wrote:
1kWh per kilogram is 3.6 MJ/kg.

But it is an order of magnitude (more or less) better than what we have
now, and would certainly be useful for electric ground transportation.

On 2011-06-27, Orval Fairbairn wrote:
Hextane? I don't think so! Don't you mean octane (C8H18)?

It doesn't matter for this calculation, the numbers work nearly the same
for any alkane.

C8H18 + 25 O = 8 CO2 + 9 H2O

Molar weight of C8H18 = 114
Molar weight of O = 16

So for each 114g of C8H18 we need 400g oxygen. Or around 3.5 parts
oxidiser to each part fuel. Pretty much the same.

I stand by my analogy in that, even though the nitrogen does not
participate in the chemical reaction, it still plays an important role
in the propulsion equation, by providing a working medium to receive
heat and expand to push pistons or to turn turbines.

But it cannot be used to compare with chemicals required in batteries,
because batteries do not need this at all! If you want to compare
against the mass that must be included in a battery, how can you
include the nitrogen? It doesn't make sense, because batteries do
not need the equivalent of nitrogen carried along with them. Batteries
are not heat engines, they don't need a working medium to transfer heat
or turn turbines. So a comparison involving nitrogen is just not valid,
so I would reconsider standing by that particular analogy because it's
just incorrect.

Dylan Smith wrote:
On 2011-06-27, wrote:
1kWh per kilogram is 3.6 MJ/kg.

But it is an order of magnitude (more or less) better than what we have
now, and would certainly be useful for electric ground transportation.

That depends on what you mean by "what we have now".

The only chemistry seriously concidered for vehicle use these days is
lithium.

battery MJ/kg fraction of 3.6 MJ/kg

lithium sulphur 1.8 2
lithium ion .72 5
lithium manganse 1.01 3.6
lithium thionyl chloride 2.5 1.4
lithium ion nanowire 2.54 1.4

lead acid .14 25.7


So yeah, a 3.6 MJ/kg battery would be more than an order of magnitude
better than a lead acid battery, but nowhere near an order of magnitude
better than existing lithium technology as it is only 1.4 times better
than the best of the chemistries currently being developed.

--
Jim Pennino

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wrote:
100LL Avgas is 44 MJ/kg.

Batteries need to be able to produce better than 20 MJ/kg to be
generally usefull for transportation.

The Avgas energy density is not comparable to battery energy density
because it doesn't factor in thermal to mechanical conversion. Current
automobile engines extract only about 20% of that 44 MJ/kg. Electric motors
are anywhere from 75% to 95% efficient in converting electrical power to
mechanical power.

So a battery with ~11 MJ/kg powering an 80% efficient electric motor has
the same usable energy density as Avgas powering an internal combustion
engine.

Setting the goal for battery energy density at 20 MJ/kg would simply be
wrong because it uses the wrong numbers.

Jim Logajan wrote:
wrote:
100LL Avgas is 44 MJ/kg.

Batteries need to be able to produce better than 20 MJ/kg to be
generally usefull for transportation.

The Avgas energy density is not comparable to battery energy density
because it doesn't factor in thermal to mechanical conversion. Current
automobile engines extract only about 20% of that 44 MJ/kg. Electric motors
are anywhere from 75% to 95% efficient in converting electrical power to
mechanical power.

So a battery with ~11 MJ/kg powering an 80% efficient electric motor has
the same usable energy density as Avgas powering an internal combustion
engine.

Setting the goal for battery energy density at 20 MJ/kg would simply be
wrong because it uses the wrong numbers.

There is a difference between the theoretical efficiency of a motor of
any type and the obtainable efficiency of a real world motor.

The 20 MJ/kg assumes that a real electric airplane motor would be about
twice as energy efficient as a real gasoline airplane motor.

We can quibble about exactly what that number is, but a factor of 2 seems
to me to be a realistic number.

And since airplane engines spend most of their time operating at a single
point in their power curve by design, while automobiles spend a lot of
time at different points in their power curve by necessity, the overall
real efficiency of an airplane engine is a bit better than an automobile
engine.


--
Jim Pennino

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