contrails

On Jan 12, 5:08*pm, Martin Gregorie
wrote:
On Tue, 12 Jan 2010 08:12:31 -0800, bildan wrote:
On Jan 11, 6:56*pm, Martin Gregorie
wrote:
On Sun, 10 Jan 2010 12:47:53 -0800, Tom Gardner wrote:
2) If everyone turns their thermostats one degree closer to the
outside temperature, drives a smaller car, and switches off phone
chargers when not in use, will an energy crisis be averted?

My sister pointed out recently that British people tend to keep their
houses warmer than we did/do in NZ, so turning down the thermostat is
not a hardship - just put on a pullover over your T-shirt in winter.

Smaller cars is a problem for us in the trailer towing fraternity. My
main gripe with the current crop of electric and hybrid cars is that
nobody mentions towing, that I've seen anyway. There's one exception:
Aptera say NO TOWING up front. I guess the same goes for many of the
rest but they're too chicken to mention it.

Hungry chargers are just stupidly bad technology and should be banned.
Chargers that use no power[1] when they're plugged in but not connected
to anything have been around for at least 8 years, so there's no excuse
for selling one that burns power when its under no load.

Anyway, I just looked at four chargers I happened to have handy and
here's what it shows they burn when plugged into the mains and
disconnected from the things they charge:

18 month old Lenovo laptop PSU (65w o/p) * * * *0 * watts. my much
older Thinkpad 560Z PSU (54w o/p) * * * 1.9 watts. iPAQ 3630 PSU (10w
o/p) * * * * * * * * * * * * 2.0 watts. 2001 Motorola T250 phone
charger (2.5w o/p) * * 0 * watts.

[1] I recently bought myself a power meter for a tenner from Maplins.
It which reads to 0.1 watts, so a reading of 0.0 should mean 50 mW
consumption or less. These power meters are simple to use: they have a
13 amp plug on the back and a 13 amp socket on the front, so you just
plug them in between the wall and the device you want to measure.

--
martin@ * | Martin Gregorie
gregorie. | Essex, UK
org * * * |

I suspect the concept of "powered trailers" will pop up more frequently..
*This is not an unproven concept since the mining industry has used it
for years.

If you use a load cell to measure the push-pull loads at the trailer
hitch, the data can be used to control electric motors in the trailer
wheels. *If a glider *trailer housed a large battery, possibly charged
with a large solar panel on top and wheel motors, it could minimize the
loads imposed on the towing vehicle by essentially powering itself. *The
wheel motors would also provide regenerative braking.

The whole car-trailer combo then becomes a parallel hybrid which permits
the use of a much smaller and less powerful car. *The fuel savings while
towing would be small compared to the fuel savings achieved by driving a
small, fuel efficient yet tow capable car when not towing.

The energy capacity of the trailer battery pack coupled to an inverter
could also power things like power tools and polishers when parked at
the airport.

That sounds good, practical, even. I've seen film of power trailers
behind Landrovers which seemed remarkably good at ploughing through mud
in off-road tests. Do you know if there are stability problems with these
rigs at highway speeds? I ask because I expect mining trailers would be
somewhat slower and the film didn't show anything operating at much over
10 mph.

--
martin@ * | Martin Gregorie
gregorie. | Essex, UK
org * * * |

I guess it could be done wrong so stability problems ensued. However,
electric wheel motors create an opportunity for dynamic stability
control. One motor could be instantly braked while the other powered
forward to counter sway. Since the motors are directly coupled to the
wheels, this could happen at the speed of electronics. Accelerometers
in the trailer would sense sway. I would think it could be done in a
way to create dead solid stability.

bildan wrote:

That sounds good, practical, even. I've seen film of power trailers
behind Landrovers which seemed remarkably good at ploughing through mud
in off-road tests. Do you know if there are stability problems with these
rigs at highway speeds? I ask because I expect mining trailers would be
somewhat slower and the film didn't show anything operating at much over
10 mph.


I guess it could be done wrong so stability problems ensued. However,
electric wheel motors create an opportunity for dynamic stability
control. One motor could be instantly braked while the other powered
forward to counter sway. Since the motors are directly coupled to the
wheels, this could happen at the speed of electronics. Accelerometers
in the trailer would sense sway. I would think it could be done in a
way to create dead solid stability.

SparrowHawk owners, and maybe PW-5 owners, probably are looking forward
to towing with EV!

A lot of the glider pilots I know bring the glider over the mountains to
Ephrata and leave it there all season, then take it home. They could
borrow or rent a vehicle to do that, and use an EV or other high mpg car
to go soaring the rest of the time. Pilots with self-launchers often
avoid a lot of towing, since they can fly from a nearby airport instead
driving to someplace with a tow plane, and don't need retrieves. Works
for me.

I like the idea of a powered trailer, though.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly