OT: Petrol consumption

"Eeyore" wrote in message news: snipped-for-privacy@REMOVETHIS.hotmail.com...

Yes. I think it has become slightly less noticeable on modern cars and with modern lubricants and fuel injection, but on older models, there were days when the engine just wanted to 'sing', and others when it felt like half the cylinders were missing!. I'd put 90% of it down to the mixture control on these engines though. Temperature is the big beast in regard to overall engine 'output'. On light aircraft, you use a slightly 'safe' factor of

10% loss in take-off performance for every 10C change in air temperature...

Best Wishes

this is the correct answer, the fuel cost to run the headlights is MUCH lower compared to the "probability cost" of reducing the chances of having an accident.

Mark

Sure it's true. The heater fan runs faster. (But in some weather in some cars with electric cooling fans, their duty cycle might go down, offsetting the heater fan's extra draw.)

The bulbs I remember were about 60 watts apiece. I doubt if modern bulbs run less. Tail-light bulbs IIRC are about 10 watts. The alternator efficiency is about 90%, and the battery discharge-recharge cycle about

80%. I guess that the lighting system consumes about 1/5 hp.

Jerry

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Engineering is the art of making what you want from things you can get.
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Not for those in the utility business!

More like 3/4. (Actually, .746, I remember it as half of 1492, a significant date in history.)

Drivers of Sherman tanks? :-)

Jerry

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Engineering is the art of making what you want from things you can get.
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In all cars. Usually, though, the AC condenser is in front of the engine radiator, so th radiator's cooling air is warmer with AC on.

Jerry

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Engineering is the art of making what you want from things you can get.
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I kept the ignition timing on the edge of too advanced in my '53 Ford F-head. I could just make it knock a little between 35 and 45 mph when floored in third gear. That is, except on humid days. Fog was just like retarding the timing. The engine ran smoother, but with less oomph.

Jerry

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Engineering is the art of making what you want from things you can get.
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Some old military aircraft engines injected water to make the engines run better.

The practice started with drag racers before WWII. As one story goes, an aircraft mechanic in the Pacific theater who gad been a drag racer in civilian life equipped his pilot's P-47 Thunderbolt with a make-shift water-injection system to better defend against the more nimble Japanese Zeros. (The Thunderbolt was a magnificent fighter, as heavy and with as much horsepower as a DC-3 cargo plane. It was heavily armed and armored, and fast on the level. Because of its weight, it was relatively slow to turn and climb. The Zero had no armor at all, not even room for a parachute. They would climb rapidly and dive down on the Thunderbolts, shooting through the canopy if the pilot didn't roll.

The mechanic's word to his pilot was supposedly something like "If you get into trouble, pull this handle. Horsepower should go from 2300 to

3000 if the engine doesn't blow up." Later tests indicated something more like 2800 than 3000, but it was enough. When a Zero tried to outclimb him, the pilot headed straight up and, hanging on his prop, raked the Zero's belly.

All was not immediately well, however. The pilot included details of the maneuver in his debriefing, and the base commander court martialed both him and his mechanic for unauthorized tampering with Government property. The court martial order was sent for approval to the division general, who quashed it and ordered the modification made to all the Thunderbolts in his command, under the tutelage of the mechanic.

Can anyone confirm the details? I heard the story from a returning veteran, with no corroboration.

I was once shot at (sort of) by a P-47, but that's another story.

jerry

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Engineering is the art of making what you want from things you can get.
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Not the details. BUT I've read similar about the war in Europe.

For perspective my parents were married 12/06/41

when they retrieved my mother's affects after the honeymoon

My grandfather is reported saying "SEE WHAT YOU STARTED"

lol

I heard the story from a returning

I didn't know there were any Jugs in the Pacific.

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  Keith

Not just to 'make them run better'. They could run with higher boost pressures, and/or the ignition more advanced (just like the car in the above quote), without knocking. Adding water is not really quite like retarding the timing. It has a whole 'series' of effects, but the main ones are cooling the mixture, and cooling the combustion chamber. On the car, the mixture, and induction pressures used were fixed, but on most aircraft, the mixture can be adjusted, and with a supercharger, you can run with more boost to get more total power. It was tried as early as the 1920's, by Sir Harry Ricardo (he also came up with the 'octane' designation for fuels), but first came into 'common' use on the latter supercharged engines in WWII, where a 'combat power' setting, used this. Both UK, and US aircraft used this. You actually can get higher fuel economy with this. The problem of course is the need to supply water...

Best Wishes

Ah, we've digressed to car stuff. Yay!

FWIW, in the 70s I knew a guy who was a 747 captain for PanAm. In those days he'd said that the 747 carried more weight in water than in fuel to support the water injection in the turbofans.

A lot of guys who do performance tuning on cars with superchargers still use water injection to cool the air charge under pressure. The thing I've found really strange is that the optimum juice to use for this is windshield washer fluid. So what a lot of people do is just run a pump line from the washer reservoir to the high pressure side of the supercharger and trigger the pump with a particular boost level. Works like a champ.

Since P-47s had substantial forced induction I could see the same sort of thing happening, but whether or not it just cooled the intake charge or actually got injected into the jugs it would be having different effects.

I'd also heard that a side effect of in-cylinder water injection in aircraft engines was accelerated corrosion of the cylinders (or heads, I don't recall). So it was a tradeoff.

Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions.

Uh, only assuming that one would be as likely to drive in the dark if the headlights were not equipped.

Do you try to fly your car even though it doesn't have wings?

Ya gotta give people _some_ credit for having brain cells.

Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions.

*WHY*

Have you EVER directed traffic at a fire or accident scene?

I have!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I was a Fire Police Officer in Ithaca New York Fire Department

Do you understand that otherwise intelligent people have problems understanding that a 100 ft ladder parked crosswise of their intended route presents a problem?

And I have even better stories.

Screenwash often contains ethanol. The ethanol evaporates and absorbs latent heat, cooling the intake air.

Graham

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From the link I posted,

"By the end of the war, the Thunderbolt had been used in every active war theater with the exception of Alaska."

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Jerry

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Engineering is the art of making what you want from things you can get.
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Un bel giorno Eric Jacobsen digitò:

He probably meant during the day:

In several countries (like Italy) it is mandatory to keep the headlights switched on during the day.

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asd

Eric must be a cool frood, and knows where his towel is

martin

LOL ! I like it.

Graham