Electrically Powered Ultralight Aircraft

On Aug 6, 4:52 am, Larry Dighera <LDigh...@att.net> wrote:
> Electrically Powered Ultralight Aircraft

It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to see
them as viable in the distant future either).

That said though, I recently saw an article somewhere about an
electric car with a stirling engine tucked away in the back (Deam
Kamen was in on it somewhere - he's the Segway and fancy wheelchair
guy).

On the face of it, that seems like not a bad idea for how an electric
aircraft could be realistic - take your stirling engine, hook it
through a smaller, cheaper, lighter battery system to your electric
motor. The battery would act as a buffer (capacitor) to allow for
stored energy to do rapid changes in power to the drive motor, the
stirling engine would tick away at a constant rate feeding it's
generated electricy into the battery.

But then, I'm no engineer, I'm sure it's already been discounted as
impractical by the real engineers :) Maybe the stirling engine ends
up so big and heavy to produce the power required that it's useless.

On Aug 6, 1:14 am, James Sleeman <bitsybof...@> wrote:
> On Aug 6, 4:52 am, Larry Dighera <LDigh...@att.net> wrote:
>
> > Electrically Powered Ultralight Aircraft
>
> It's a nice idea, but realisitically there are too many problems, not
> the least of which is battery size, weight, cost and safety. I don't
> really see batteries as a viable in the near future (I struggle to see
> them as viable in the distant future either).
>
> That said though, I recently saw an article somewhere about an
> electric car with a stirling engine tucked away in the back (Deam
> Kamen was in on it somewhere - he's the Segway and fancy wheelchair
> guy).
>
> On the face of it, that seems like not a bad idea for how an electric
> aircraft could be realistic - take your stirling engine, hook it
> through a smaller, cheaper, lighter battery system to your electric
> motor. The battery would act as a buffer (capacitor) to allow for
> stored energy to do rapid changes in power to the drive motor, the
> stirling engine would tick away at a constant rate feeding it's
> generated electricy into the battery.
>
> But then, I'm no engineer, I'm sure it's already been discounted as
> impractical by the real engineers :) Maybe the stirling engine ends
> up so big and heavy to produce the power required that it's useless.

For a battery-powered car todays practical approach is to have a
second engine for backup or as you suggest to generate electricity.
When they start selling cars only powered by batteries I'm going to
invest in a tow truck business. For aircraft the best use for
batteries today is to start the engine. Lange has demonstrated what is
possible with today's batteries/motors and while it provides an
attractive self-launch the cost and range tradeoffs bring it back into
perspective.

In article <1186384454.047870.95690@z24g2000prh.. com>,
James Sleeman <bitsyboffin@> wrote:

> On Aug 6, 4:52 am, Larry Dighera <LDigh...@att.net> wrote:
> > Electrically Powered Ultralight Aircraft
>
> It's a nice idea, but realisitically there are too many problems, not
> the least of which is battery size, weight, cost and safety. I don't
> really see batteries as a viable in the near future (I struggle to see
> them as viable in the distant future either).

Look at the problem this way: In an all-electric machine, you carry ALL
of your energy supply with you: fuel and oxidizer -- to make electricity.

With any IC engine, you carry the fuel only -- the air is free (20%
oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
each gallon of fuel.

Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
have to carry an additional 7500 lb of air.

That is a lot of weight for a 3000 lb aircraft!

In article <orfairbairn-5D8336.11534806082007@news.west.>,
Orval Fairbairn <orfairbairn@> wrote:

> In article <1186384454.047870.95690@z24g2000prh.. com>,
> James Sleeman <bitsyboffin@> wrote:
>
> > On Aug 6, 4:52 am, Larry Dighera <LDigh...@att.net> wrote:
> > > Electrically Powered Ultralight Aircraft
> >
> > It's a nice idea, but realisitically there are too many problems, not
> > the least of which is battery size, weight, cost and safety. I don't
> > really see batteries as a viable in the near future (I struggle to see
> > them as viable in the distant future either).
>
> Look at the problem this way: In an all-electric machine, you carry ALL
> of your energy supply with you: fuel and oxidizer -- to make electricity.
>
> With any IC engine, you carry the fuel only -- the air is free (20%
> oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
> each gallon of fuel.
>
> Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
> have to carry an additional 7500 lb of air.
>
> That is a lot of weight for a 3000 lb aircraft!

DUH! I meant 4500 lb of air! That is still a lot of weight penalty.

> There is a fundamental problem with attempting to power an aircraft
> with batteries: The propulsion system must not only move the vehicle
> forward as it would with an automobile, but it must also
> simultaneously maintain the aircraft's altitude;

This is significant at low airspeeds. At higher airspeeds overcoming
wind resistance takes much more power than maintaining altitude.

> unlike an automobile
> that only requires a small amount of energy to overcome rolling and
> wind resistance once in motion, an aircraft can't coast without losing
> altitude,

It sure can, until it loses speed and stalls.

Bartek

"Michael Ash" > wrote

> The extra drag caused by the extra weight of the batteries and
> the rest of the hybrid system would probably outweigh any efficiency gain.

Probably? You are being far too kind. A redundant power system, only
helping at takeoff is GOING to waste efficiency. There is no way to avoid
that fact unless then cruise speed is going to be painfully slow.
--
Jim in NC

James Sleeman wrote:

> stick a heatsink in the wind, higher you go,
> colder it gets, more power the engine can deliver, directly the
> opposite of IC

What I didn't get from the article: Where does the "hot" come from? A fuel
burner, probably, which would have the same problems with altitude as an IC
engine, wouldn't it?

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Gattman wrote:
> "Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote in message
> news:13beqm8gnlqf8dd@news.supernews.com...
>
>> Come on, it's not like there isn't sufficient motivation out there
>> now and it isn't coming from battlebots. If anyone comes up with a
>> battery that can power and automobile for 4 hours at highway speeds
>> and is affordable to produce they will be very wealthy.
>>
>> If they can make one that is as efficient as a tank of gasoline they
>> will shortly become very, very wealthy.
>
> I agree. It's on the way. Wasn't too long ago that terms like
> "lithium ion" and "nickle metal hydride" were unheard of to the
> common consumer.
> Five or six years ago your choices were Hawker Genesis-style Sealed
> Lead Acid or custom-built NiCad battery arrays which is what we used.
> NiMH and lithium ion weren't available or affordable but the
> proliferation of power chairs, stuff like the Segway, electric
> scooters and so forth have really pushed the demand for lightweigh,
> high performance batteries.
> -c

Do me a favor Gattman. What is the weight of the most effeicent battery that
could power an automobile at highway speed and how long will it do so and
how long to recharge?

George wrote:
>>
>
> Just a wild guess, but wouldn't this make for a very, very safe
> airplane??
> George

None would be safer, though you might find some people who would have a
problem with calling it an airplane if it couldn't get off the ground.

Gig 601XL Builder wrote:
> George wrote:
>> Just a wild guess, but wouldn't this make for a very, very safe
>> airplane??
>> George
>
> None would be safer, though you might find some people who would have a
> problem with calling it an airplane if it couldn't get off the ground.
>
>
That was my point, if it can't fly, how can it crash?? <vbg>

George