Slashdot Mirror
Jaguar's Hybrid Jet-Powered Concept Car
An anonymous reader writes "Jaguar has developed a hybrid car that runs on gas turbines. The range extended vehicle usually uses four electric motors (one on each wheel) plus a lithium-ion battery pack for propulsion, but can achieve a performance boost from a pair of gas turbines mounted in the rear. Cnet UK reports the car can do 0-60 mph in 3.4 sec. (and 50-90 mph in 2.3 sec.) and reach 205 mph while emitting less CO2 than a Toyota Prius."
This thing has a dozen or so moving parts. Granted, the turbines move pretty damn fast but electric motors and generators are extremely reliable. Four indepenent motors and two turbines menas we have redundancy on top of that.
I'm a little suspicious of the emission claims though. How much of that is from plugin? I can't imagine turbine->electric->battery->motors is an efficient drive train.
It's funny how developments that reduce the environmental impact of cars often originate from the high-performance end of the spectrum. While I'm no expert, my understanding is that sports such as Formula 1 and Indycar have done massive amounts to improve the fuel efficiency of the cars you see on the roads every day. After all, there's a clear and direct incentive when you have a high performance car out on the track to design something that can carry a smaller (and lighter) fuel tank or get away with fewer refuelling stops. And once you've developed that technology, you might as well make good use of it on a commercial basis.
Gas turbines are powerful for their weight, but not exactly economical in fuel use. The power-to-weight ratio makes them suitable for aircraft, but for cars they are just a thirsty show-off.
Nae king! Nae laird! Nae yurrupiean pressedent! We willna be fooled again!
Gas turbines are powerful for their weight, but not exactly economical in fuel use.
A friend of mine was a tank commander in the US army. He complained about the reliability of the gas turbine engines in the M1 Abrams tanks. When they break down, oil gets into the turbine, and spews itself around.
Over the radio, when your tank breaks down, you say, "I shit the bed."
On the other hand, he was really impressed with the German Leopard tank. It just uses a turbo diesel engine, so it is not so sexy, but seems to get the job done.
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
...tends to be that by definition, they only kick in when something is broken.
I used to climb a little bit. We'd be up on a thousand feet of exposure with just a thin nylon harness and some carefully tied rope. Now I'm a firefighter and have done some rope rescue classes. We don't even go on a steep hill without a far more complex (and heavy) harness system. It seemed ridiculous to me, but it was explained that if the usual way of doing things had worked then we wouldn't have been called in. Something has gone wrong, and we can't always know what it was.
The same problem exists, to us, for cars like the Prius. Lots of very high voltage cables running through parts of the car we would usually cut through to get someone out. In theory, there are safety systems that will cut power to those cables after an accident. In practice, what if the accident affected those cut-off systems? There's a manual cut-off -- I'd have to check the reference material we have, but I think it's under the back seat. If I could get to something under the back seat, I wouldn't need to cut the car apart.
When things are broken, they're ...well....broken. The safety systems may or may not be affected. I think the issue in this case is that broken at 65 miles per hour is one thing, and broken at 205 miles per hour is something else entirely.
I think if a car that was moving that fast being propelled by four independent motors suddenly found itself being propelled by thrust that was no longer balanced and centered -- I wouldn't want to be down range for quite some distance.
The problem with quotes on the internet, is that nobody bothers to check their veracity. -- Abraham Lincoln
I remember hearing about some of the problems with this, and another. A turbine also happens to be wonderful gyroscope, so Chrysler's Turbine Car (I remember seeing the TV commercials as a kid.) had an embedded gyroscope which interfered somewhat with steering. Obviously arranging the axis of the turbine correctly can take care of this, but might make it more difficult to extract power from the engine. When I heard that this new car had 2 turbines, especially after reading about the difficulty of scaling turbines downward, I thought "counter-rotating" to mitigate the gyroscopic effects.
I also have an old high-school friend that has the gearbox problem. He travels to tractor-pull competitions with his jet-powered tractor. Last I talked to him, his #1 maintenance item was the gearbox. No matter what you did, high power plus high RPMs just makes for a tough problem. I also saw the engine room of the battleship Massachusetts at Fall River, Ma. It was steam turbine powered, and the gearbox was several times the size of the turbine.
Using the turbine to drive a generator instead of trying to directly extract mechanical power out of it solves a lot of problems. But from some other reading, I get the impression that they still gear the turbines down, preferring to generate electricity at about 1800 rpm instead of the direct 30-40 krpm. Makes me wonder about the difficulties of high-rpm electrical generation, and how tough that would be to solve.
The living have better things to do than to continue hating the dead.
A plain gas turbine driving a land vehicle is impractical due to turbo lag. Gas turbines respond too slowly for throttle settings. Everyone knows about the turbo lag in the turbo-supercharged gas/diesel engines. Jay Leno has a motorcycle made from an Airforce surplus helicopter gas turbine engine. That thing runs so smoothly with nary a vibration, you would not know the machine is running unless you stand on the exhaust path. But he was saying, "There is a 0.5 sec turbo lag. You twist the throttle, the machine thinks you have suggested a speed increase, and a committee decides to approve of it and then it starts accelerating rapidly. And remember the lag is on the other end too. You shut the throttle off, and the machine produces power for another half a second before decelerating" (paraphrased. not exact words of Jay).
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
I've always thought that NASCAR in particular could reduce the thickness of their rulebook considerably by putting the teams on a fuel allowance for the race. If the cars start going too fast to be safe, pull back the fuel they are allowed to get.