Can Aircraft Be Far Behind?

wrote)
If a Cri-Cri were to be set up with electric motors and a battery, how
big (heavy) would the battery need to be to allow the pilot to: Take-off,
fly around for 15 minutes at 100 kts, and land?

Altair has a graph on their Web site that seems to show that their
batteries will give 90 Wh/kg at a 15-minute discharge rate. On the other
hand, that graph also has "Altair's Disruptive Technology" written on it,
which means it was probably produced by salesmen and not engineers. If you
take the 90 Wh/kg at face value, you'd need about 169 lb (77 kg) of
batteries.


This is why I love these groups!!

Thanks for the answer.

Ok, so 170 lbs worth of batteries it is! :-)

I have 50 lbs 'to give' swapping over to electric. So now all I need to do
is find 120 remaining lbs (55 kg) of weight, and shave THAT off the Empty
Weight of the Cri-Cri.

Gotta start somewhere! g


Montblack

http://www.technologyreview.com/Energy/18054/

describes GM's plans to build car with A123 System Li Ion batteries

On 11 Jan 2007 08:38:33 -0800, "JD" wrote in
.com:

http://www.technologyreview.com/Energy/18054/

describes GM's plans to build car with A123 System Li Ion batteries

Here's another link to information about GM's 'Volt prototype hybrid
automobile dated Jan. 7, 2007.


http://www.canada.com/topics/finance...aa&k=45978&p=2
Lutz said the engineering development of the car itself is 18
months from being completed. The batteries are about 18 months
behind the rest of the car.

How many years would that put GM's product behind the Japanese? :-(

Larry Dighera wrote:

Here's another link to information about GM's 'Volt prototype hybrid
automobile dated Jan. 7, 2007.


http://www.canada.com/topics/finance...48-a654-4000-8
b3c-aff0354600aa&k=45978&p=2
Lutz said the engineering development of the car itself is 18
months from being completed. The batteries are about 18 months
behind the rest of the car.

How many years would that put GM's product behind the Japanese? :-(

None.

All of the car manufacturers are waiting for battery technology to get to
the point where such cars can be practical. The auto manufacturers have
put electric cars on the market in the past, mainly because of
California's ZEV requirements, but they were quickly pulled when the
California regulations were retracted, since the vehicles were expensive
and the batteries had relatively short lives. Battery technology at the
time wasn't good enough to make the vehicles practical.

Battery technology has improved somewhat since then, with about double
the energy density, but they still have a long way to go before they can
compete with liquid fuels foe convenience and cost.

This is like the days when stereo equipment manufacturers were in an
ouput power race, or today's speed race with personal computer
manufacturers. Every time a new improved type of transistor came on the
market, or a new microprocessor, the builders of the final product would
quickly market the highest power stereo, or the fastest computer. They
were all pretty well at the same place in the market at the same time,
based on what was available.

The same can be said for hybrid vehicles, plug in hybrids, or all-
electric vehicles. The manufacturers need appropriate batteries to make
their products practical and cost-effective.

As far as practical aviation applications, using batteries for primary
power is nowhere near possible today, and given the huge gulf in weight
that has to be overcome, they will only be practical after a huge
technical breakthrough, making the energy density something like ten or
fifteen times what it is today. At the present rate of improvement,
assuming it can be sustained, that will take something like 50 years.

The original developer of LiIon batteries has stated that such
improvements will never happen. He feels that improvements of existing
batteries will be in safety, cost, and the ability to more quickly charge
or discharge them, but there will be little improvement in energy
density, which is what would be required for aviation application.

Montblack wrote:
Thanks for the answer.

You're welcome.

Ok, so 170 lbs worth of batteries it is! :-)

If you believe Altair. One rule of thumb for rechargeable batteries
is to apply a correction factor of 0.5 to the numbers the salesman
emits, which puts you up to 340 lbs. Also, call them up and see if they
can sell you some of their batteries if you give them a credit card
number. If they can't, then as far as you're concerned, their batteries
don't really exist.

I have 50 lbs 'to give' swapping over to electric. So now all I need
to do is find 120 remaining lbs (55 kg) of weight, and shave THAT off
the Empty Weight of the Cri-Cri.

Say the Battery Fairy gave you some batteries with an energy density
equal to gasoline. Then, going electric would let you lose the carbs,
cylinders, and exhaust pipes, which would probably help the drag a
little. The shape of an electric motor would make it easy to have a
nice smooth fairing over it, right behind the prop hub. Unfortunately
I've been putting dead D cells under my pillow for years and the Battery
Fairy has never shown up for me.

I wonder what a G1000 weighs, compared to steam gauges.

Matt Roberds