JHZR2
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LOL, if you only knew...
JMH
Engine Technology
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I was on a 91,000 ton gas turbine powered ship last September. I also has a large steam turbine that ran off waste heat from the gas turbines when they were making real power. Real data was hard to come by, but supposidly when underway it's total system efficiency was not much worse than a diesel. It was very smooth, nary a power system induced ripple in my drinks.
Nuclear fusion with its theoretical lack of negative byproducts.
The electricity produced will result in electric cars taking over.
Enter the medical field. The lack of noise from an electric car should result in a huge increse of pedestrian/bicyclist/etc collisions.
Buy stock in a bandage firm.
Wear thine helmet.
Look both ways.
The electricity produced will result in electric cars taking over.
Enter the medical field. The lack of noise from an electric car should result in a huge increse of pedestrian/bicyclist/etc collisions.
Buy stock in a bandage firm.
Wear thine helmet.
Look both ways.
It does pose a problem if there's no alternative to platinum--especially at its current price!
Imagine what the cost of platinum would be if there was a significant demand.
turbine engines only like to run in a narrow RPM band and have slow throttle responce. one example is a turboprop engine runs at a constant rpm-always, aircraft speed and power is determined by blade pitch. another example is a turbine engine could take 7-10 seconds to go from idle to 100% rpm, very slow compared to recip engines.quote:
Originally posted by Tempest:
I really don't understand why rotary or turbine engines don't rule. Their non-reciprocating nature makes them more effeciant, lighter, smaller, and with fewer moving parts than the dinosaur piston engines that we have now. Coupled with a CVT, it should be the ultimate drivetrain.
There is a reason why aircraft, helicopters, some navy ships, and even the M1 tank use turbines: more power with less weight with higher reliability and less noise.
My understanding is that the Mazda RX8's engine is roughly half the size/weight of comparable output engines, and is one of the reasons for the cars great performance (along with the twin turbos).
Caterpiller has been working on camless engines that varies valve timing and use a electric/hydralic system to actuate the valves.
Why is it then that they use a 1500HP multifuel turbine engine on the M1 tank? The M1 is the "hot rod" of all main battle tanks. Diesel piston driven tanks don't compare. It is very quiet compared to diesels.
Also, while tanks can maintain a constant speed (across open terrain/highway) for a time, they are also required to have good acceleration for off roading, urban, maneuvering, reversing and climbing hills.
The M1 has a conventional, muti-gear auto transmission as well. I would think that a properly designed CVT type set up would offset much of the drawbacks of the slower turbine response time for passenger car use. And I would think that much of the down sides of turbines could eliminated if the R&D funds of current piston engines was put into passenger car turbines.
I recall seeing somewhere that a race team in the 60's used a turbine car for a while, but that the fuel switch killed it. (All from memory so
One of the M1s biggest drawbacks is it's high fuel consumption. It's an old turbine so is even worse than a modern one. The T-type power pack arrangement takes up even more space than a modern diesel.
I worked on some study programs in the late 1980s and got to meet Dr Phill Lett, the father of the M1 tank. He even sat in on some of my design reviews. He was a brilliant Engineer with a wry sense of humor and a real gentleman.
At that time, the Army was seriously looking for a way to get rid of the gas turbine in future vehicles because of high fuel consumption. I seriously doubt that they would use one in a new clean sheet of paper tank. A tank spends most of it's life at low power levels, just what a turbine doesn't like.
that turbine engine also uses 20-50% more fuel then a diesel and costs 10x more.
it travels about 270 miles on 500 gallons of fuel.
there is certain applications that a turbine engine for transportation works excellent. basically where high horsepower is needed and fuel consumption is not much of an issue.
a new turbine engine of any size costs more then a new car + new house + a year's salary. you can't really make them "cheap".
My father worked at Garret as QC in the 80's. Garret helped to design several of the M1 systems (including the engine) so I got hear a lot about the platform.
No doubt the M1's engine is old (20+years). But like most things, technology advances. I think if the billions spent by the Auto manufactures to make a %60 parasitic engine (piston) slightly better were spent on making an inherently more efficient design (rotary or turbine) better, we would be seeing more reliable and fuel efficient vehicles.
The M1 is a gas guzzler for sure. Something like 3GPM (that's Gallons per Mile!) at speed. But it also weighs 63 tons and uses caterpillar tracks. Passenger car don't suffer from these drawbacks.
If turbines aren't the way to go, what makes rotary so bad?
No doubt the M1's engine is old (20+years). But like most things, technology advances. I think if the billions spent by the Auto manufactures to make a %60 parasitic engine (piston) slightly better were spent on making an inherently more efficient design (rotary or turbine) better, we would be seeing more reliable and fuel efficient vehicles.
The M1 is a gas guzzler for sure. Something like 3GPM (that's Gallons per Mile!) at speed. But it also weighs 63 tons and uses caterpillar tracks. Passenger car don't suffer from these drawbacks.
A turbine needed to power a car would not need to be all that large. And with the mass production capabilities of modern auto plants coupled with fewer moving parts, I thinks costs would come down quickly.
Along with greater performance. Most other diesel tank engines are in the 750HP area.
Again, it all comes down to scale. There are what, maybe 3-4000 M1 tanks out there? With production of those spread out over 20 years. Your talking about building just a few units a year, and those have to meet Mil spec with all the associated paperwork and bull **** that drives prices through the roof. Auto manufactures pump out those numbers in a week and don't have the Mil spec overhead.
If turbines aren't the way to go, what makes rotary so bad?
All else being equal, in the real world the turbine and rotary inherently have lower thermal efficiency than arecip engine. I'm sure Mr Google can help you find out why in an hour or less.
What was Garret doing working on a Lycoming gas turbine? I remember the M1 power train designers talking about working with Lycoming on the power train, but Garret?
What was Garret doing working on a Lycoming gas turbine? I remember the M1 power train designers talking about working with Lycoming on the power train, but Garret?
XS650: Thanks for the info. I'll have to look that up when I get some time.
As I recall, my Dad said they were working on heat exchangers for the engine. My Dad did a lot of work with those. I believe in the end though that the contract went to another company. My Dad said they had to get special permission from the EPA (Cali) in order to run a 24hour engine test even back then.
I also recall them working on the NBC/overpressure systems and some others that I forgot about. It's been a while.
As I recall, my Dad said they were working on heat exchangers for the engine. My Dad did a lot of work with those. I believe in the end though that the contract went to another company. My Dad said they had to get special permission from the EPA (Cali) in order to run a 24hour engine test even back then.
I also recall them working on the NBC/overpressure systems and some others that I forgot about. It's been a while.
The NBC/Overpressure system sounds right. I wasn't involved with those people at GD but have run across Garret in NBC/Overpressure system work at another company. Also APUs.quote:
Originally posted by Tempest:
XS650: Thanks for the info. I'll have to look that up when I get some time.
As I recall, my Dad said they were working on heat exchangers for the engine. My Dad did a lot of work with those. I believe in the end though that the contract went to another company. My Dad said they had to get special permission from the EPA (Cali) in order to run a 24hour engine test even back then.
I also recall them working on the NBC/overpressure systems and some others that I forgot about. It's been a while.
Chrysler made a Turbine powered car in the 60's. I saw one at the original Harrah's auto museum. There is a guy with a web site about it. His dad got to drive on for a few months.
http://www.turbinecar.com/turbine.htm
The thermodynamic cycle of a turbine engine is much less efficient than the thermo cycle of a 4 cycle gas engine (otto cycle). Then again the diesel thermo cycle is more efficient than the Otto cycle.
Turbines are too innefficient for cars.
http://www.turbinecar.com/turbine.htm
The thermodynamic cycle of a turbine engine is much less efficient than the thermo cycle of a 4 cycle gas engine (otto cycle). Then again the diesel thermo cycle is more efficient than the Otto cycle.
Turbines are too innefficient for cars.
Union Pacific Rairoad ran a gas turbine locomotives for awhile. They was very powerful, and not as efficient as a diesel. The stopped one under an overpass once and melted the asphalt pavement on the road above it with it just idling.
The M1 tank puts so much heat out the rear that the army had to redesign the dyno vehicles that the drag behind tanks for test purposes at the proving grounds. They put heat shields on the front, insulated the cabs better and increased the air conditioning for the cab.
I take it you haven't driven a Model T lately. Yup, it had a two-speed planetary, but each of those speeds had an infinitely variable friction contraption that changed the ratio as you pressed on one of the two 'forward' pedals (there was a third pedal for reverse). A far cry indeed from a modern CVT but not all that different in concept.
From my book "Nebraska Tractor Tests Since 1920" by C.H. Wendel.
Test #0766
Gasoline fuels, the all-time best fuel economy at full rated power was the 1960 Oliver 1800 which developed 13.18 horsepower hours per gallon. I converted that to pounds once but don't have the numbers handy.
Joe
I take you have never driven a Model T or seen a T transmission taken apart. There is no variable ratio device in one.
Find a schematic for T transmission and you can see for yourself.
http://www.old-carburetors.com/1922 Ford Operators Manual/target6.html
The three pedals were brake, reverse and clutch.
The clutch pedal not being the same as modern clutch pedal. If you pushed it all the way to the floor it was in low gear, if you let it all the way up, it was in high gear. In between it was either fully disengaged or slipping and frying the bands. You didn't drive them that way anymore than you would slip the clutch on a modern car and call it a variable ratio transmission. Model T owners manuals are easy to find online, I looked one up to confirm my memory because I only drove one once briefly.
What was the BSFC of the Oliver at light throttle, like a car being driven down the road? Hint, it wouldn't have been very good compared to modern engine.
Here's BSFC map for an older Saturn, not an inefficient engine but not the best. As you can see it's a bit more efficient than your old tractor at the best BSFC. Because of the nature of modern engine design and control systems, it will be far more efficient than the Oliver producing the power needed for ordinary driving.
I really don't understand why rotary or turbine engines don't rule. Their non-reciprocating nature makes them more effeciant, lighter, smaller, and with fewer moving parts than the dinosaur piston engines that we have now. Coupled with a CVT, it should be the ultimate drivetrain.
There is a reason why aircraft, helicopters, some navy ships, and even the M1 tank use turbines: more power with less weight with higher reliability and less noise.
My understanding is that the Mazda RX8's engine is roughly half the size/weight of comparable output engines, and is one of the reasons for the cars great performance (along with the twin turbos
).
There is a reason why aircraft, helicopters, some navy ships, and even the M1 tank use turbines: more power with less weight with higher reliability and less noise.
My understanding is that the Mazda RX8's engine is roughly half the size/weight of comparable output engines, and is one of the reasons for the cars great performance (along with the twin turbos
Turbines are less fuel efficient that recip engines in real world automotive applications. So are rotary engines.quote:
Originally posted by Tempest:
I really don't understand why rotary or turbine engines don't rule. Their non-reciprocating nature makes them more effeciant, lighter, smaller, and with fewer moving parts than the dinosaur piston engines that we have now. Coupled with a CVT, it should be the ultimate drivetrain.
There is a reason why aircraft, helicopters, some navy ships, and even the M1 tank use turbines: more power with less weight with higher reliability and less noise.
My understanding is that the Mazda RX8's engine is roughly half the size/weight of comparable output engines, and is one of the reasons for the cars great performance (along with the twin turbos).
Turbines do better in applications where average power output is high percentage of peak power. That and their lighter weight are the reason they are popular in aircraft. They are generally used in ships where performance is valued over fuel efficiency, but can be pretty efficent in a naval application where average loads are fairly high.
Here's another interesting twist to ICE design -
http://www.revetec.com/
I haven't been following along to see how there R&D has been going, but neat all the same.
http://www.revetec.com/
I haven't been following along to see how there R&D has been going, but neat all the same.
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