Diesel/Electric Cars?

[Broomstick]

@j_sum1

And I think it will be a while before you see a model aeroplane with a diesel engine.

I’m no authority on model airplane engines, but I do know that there is at least one viable and working diesel engine for small airplanes. Not personally familar with it, but I do know it inolves some sophisticated computer controls to manage the fuel flow and engine conditions. First developed in Europe, it is now entering the US market. Costs a little more than a conventional gasoline piston (and that’s a significant cost right there, if you’re talking airplanes) but you burn less fuel per unit of time for the same or similar performance. Given the price of fuel, over the lifetime of the engine, it may be the same cost or even less. Given the pressures to eliminate aviation gasoline, over the next decade or two the small planes may well convert to diesels, which can run on standard jet fuel.

[GorillaMan]

@TheLoadedDog

I think it’s not so much the low start up torque generally as the fact that a steam locomotive trying to accelerate at very low speeds delivers its power in rather cumbersome pulses, and this leads to serious wheel slip problems. …The main cause of wheel slip in this case was the regulation of power (often these big locos would be applying too much), and this required an experienced hand on the throttle, …

As a diehard railfan and steam lover, I have to be honest with myself, and say that, despite her beauty, steam is a total bitch of a form of motive power. Very inefficient.

The world isn’t completely free of people looking for ways to modernise steam traction - not least with an eye on long-term oil supplies. And there can be no doubt that it would be possible to effectively neutralise the major wheel-slip problems through traction-control systems. There’s a good page of links here.

[zut]

@Balthisar

The problem with a purely electrical drive is demand horsepower, meaning accelleration. You’d need a big, big generator (and consequently a motor) to give instant power needed for the type of accelleration we expect. Or, as I said, another energy storage system for that reserve power.

Hybrids do both, though. Their motors run an electric drive system, and directly drive a transmission when power is needed.

There’s two kinds of hybrids: 1. the parallel hybrid, where the engines directly drive the wheels, and additional power is supplied or absorbed by a parallel (electric) system. This is the system the Ford Escape, and Toyota Prius, and all other available automotive hybrids that I can think of off-hand, use. 2. the series hybrid, where the engine is not directly connected to the wheels, and all the power supplied by the engine is converted into another form (electricity). This, I believe, is what diesel-electric locomotives use. You could develop either series or parallel hybrid automobiles, there being advantages and disadvantages to each configuration. A significant disadvantage to series electric hybrids is what you say here:

@Balthisar

The problem with a purely electrical drive is demand horsepower, meaning accelleration. You’d need a big, big generator (and consequently a motor) to give instant power needed for the type of accelleration we expect. Or, as I said, another energy storage system for that reserve power.

There are series diesel-hydraulic hybrids in the development stages. Hydraulics will give you the instant power you need in a series configuration (there’s some engineering trade-offs, of course).

@El_Kabong

Interesting thread. Hope this isn’t too much of a hijack, but given the relatively higher fuel efficiency of diesel vs. gas, why have all the manufacturers that produce hybrid vehicles so far selected gasoline, rather than diesel, for the drive/battery-charging engine?

In addition to what mike1dog said, I’d hazard that another issue is consumer perception. For the people that buy Priuses and Insights, diesel has the perception of being smelly, polluting, and unavailable – exactly what these people don’t want in a hybrid automobile. However, note that Chrysler is making a parallel diesel-electric hybrid Ram truck (albeit only a “mild” hybrid with a souped-up starter motor), so not everything is gasoline.