Russian Revolutionary Hybrid car

Power is torque times (rotational) speed, so "the power output divided by the speed" _is_ torque (give or take some unit conversion from rotational wheel speed to linear vehicle speed, and to allow for the fact that you probably weren't measuring the rotational speed in radians per second).

about 3300 *passengers*

About 27 passenger miles per gallon.

Yes, but the situation exists where wheel torque may peak where engine torque does not, through a gear change.

Which is why we have 5,6,7 speed gearboxes these days instead of 3 or 4 especially in racing.

Actually ships are absolutely in the 'vee squared' - or worse - regime. Run them at 5-8mph and they are hugely fuel efficient.

I cant remember the actual equations but drag goes up massively with speed - and tends to hit almost a 'sound barrier' at certain speeds related to hull length.

If we're comparing fuel consumptions across modes of transport, could we at least compare like with like?

The QE2 and QM2 would compare more closely to a Pullman train or an executive jet such as a Learjet or Gulfstream than a fully loaded 737. The closest comparison to the 737 would be the ferries running from Plymouth to Santander, or a train running from London to Berlin.

Yes, someone else had already pointed out that you have to consider the width of the power band, not just the peak. More gears means you can use a narrower band/stay closer to the peak.

Similarly modern racing bicycles have 20 or 22 gears, not the 10 they had when I was young, even though the narrower chains needed cost more and wear out faster. (Though that's complicated by overlap - it isn't 22 usefully different gears.)

The obvious endpoint is a continuously variable transmission of course, but making one which can transmit high powers at high efficiencies is tricky.

It's closer to a cube law, from what I remember.

Wikipedia to the rescue:-

If you change gear so the engine is no longer on maximum torque then neither is the wheel. Unless you think there is something in between them that produces 'energy'? All the gearbox does is multiply the engine's torque minus some losses due to friction.

Because the useable torque band on that sort of engine is narrower.

Indeed - they're pretty impressive when they do run away, though...

Starving them of air's really the only way to do it, assuming you want to risk getting close enough to one that might be about to go bang in order to shove something in the intake :-)

cheers

Jules

Bloke I worked with told me of one large marine diesel (in use as a generator power source) he witnessed that ran away - somebody grabbed a sledgehammer and ran past the fuel pump swinging the sledge hammer at it as he passed. Unfortunately, the pistons chose just that moment to make a bid for freedom through the crankcase. Lucky f***er only got a broken leg for his trouble. If it was running on its own oil, the gesture was futile anyway, and he'd have been better off standing at the door of the shed pointing and laughing.

In message , snipped-for-privacy@gmail.com writes

Absolutely fantastic to fly in. Taking off and climbing was just unbelievable. The acceleration pushed you right back in your seat. p to 36000 ft in no time then climbing up to 50000 and watching the speed climbing up through mach 1 and beyond. Brilliant.

In message , "Dave Plowman (News)" writes

Which whilst I cannot quote the exact wording is the gist of the warning notice in MOT stations - make sure your governor is working

Unfortunately in my case it didn't.

If I'd thought quickly enough I might have tried stalling it.

So which cross Atlantic ferry do you have in mind?

If they were still running, the old Union Castle line mail ships. Any passenger ship where the main purpose of the voyage is to arrive, rather than to have travelled. Now almost all made redundant on the Atlantic by the speed and convenience of the airliner.

This one, maybe:-

Technically, some of the Cal-Mac ferries do cross parts of the Atlantic, and some of the ferries in the Far East do carry out long sea passages.

That is an artefact of the units you are using - HP and ft lbs.

Try it in kW and newton metres and you'll get a radically different answer.

Australian engines obey the exact same laws of physics as American engines. The only real distinction between the two is that Aussie engines are designed to run upside down."

also

Andy

"Guest Capacity: 4,375 guests (total)"

_passenger_ miles per gallon (excluding crew) ... errr... 12800kg in gallons ... err...3500-ish ... 166gals per nm = 145 gals per statute mile - about 30 passenger statute miles per imperial gallon.

And that beast only does 21kts, not the 28-ish of QE2. About the same speed as a pre-WW1 liner.

Andy

No Dennis you terminally dishonest f****it.

If you try to claim that the crew are not passengers on the ship the, by the same argument a car has no passengers at all if there is only a driver on board.

No Dennis. 46 miles per passenger gallon.

wave drag - the "sound barrier" one is when the ship goes at the same speed as a wave of the same length.

Being old fashioned I know that the speed of a wave in knots is 1.34 times the square root of the waterline length in feet.

So for a 16 ft dinghy, just over 5 knots. If it wants to go faster it must plane - rise up on top of its own bow wave.

For a 100ft ship, 13 kts. Ships don't normally plane, but a destroyer or such may be able to go through its bow wave - forced mode. Not fuel efficient.

For a 400ft one, 27 kts.

Andy