@Texas,a little sketchy on details,has a special cooling system and an Aluminum block and I’m assuming its compression ignition(I think I read the article on either the “Gizmag” or “Aviation week” site respectivaly,anyway it had enough output to lift that Chopper off the ground(I know they have used “Rodacs” in experimental aircraft before(the climb rate was great!)
@Bill,I imagine this engine wouldnt cost quite as much as a Turbine,but I have to agree,you cant beat a Turbine in this application,the fuel flow on these new turboprops must be really in line now, a turbine is just a terriffic engine,the adaptibility to different fuels is another plus for a turbine.One Guy told Me there are huge industrail turbines that can run on coal dust.
I once lived right next to an interstate highway where it curved and trucks were always using their engine brakes. I am fully convinced there are different styles and maybe even “variability” in these braking systems. Some emitted a very mild sound while about 2 per day were downright painful. The sound was like a meat tenderizer to the entire body. There also seemed to be variability or steps like half the cylinders were being used for braking or all of them for braking. Maybe they just downshifted and that is the variability/steps I was thinking about.
Then there were the occasional tire blowouts and the concussion from those sounded like a bomb going off.
You might be referring to “Rotax” engines:
Gas turbines are efficient only if the waste heat is recovered, otherwise, not so much.
Gas turbines are used as “peakers” in power plants. The steam turbines provide the base load and gas turbines are fired up when there is a large peak demand for power. A gas turbine can come on line in a matter of minutes, a steam turbine not.
Gas turbines are really in their element in aircraft where light weight power is more important than fuel efficiency. After all, what good is a super efficient engine if it weighs so much that it causes the airplane to need twice as much power to fly? Also, gas turbines have a small operating point sweet spot, which is not a problem in aircraft where they cruise at around 75% power for every part of the trip except for takeoff and landing. But the small sweet spot is what killed them for auto use where you might need 200 horsepower to pass and accelerate but then that engine is throttled back to 10 or 15 horsepower to cruise down the highway at 60 mph.
Perhaps small micro turbines may be used in future hybrid cars where the turbine is either on or off instead of being throttled, topping off the battery that powers the electric motors.
Ships once embraced steam turbines but today they have returned to huge Diesel reciprocating piston engines…Much higher efficiency…When the railroads were converting from steam to diesel power, they built a few steam turbine locomotives but they didn’t work out…
@CW,most “Jakes” are staged,mostly for safety when slick and slight downgrades,most of the time it is accomplished by the amount of cylinders involved.a lot of trucks use either a 2 stage or 3 stage engine brake.
@Insightful,a “Rodac” is a aluminum block highly modified Chevy small block engine(very powerful and light)My comment about the gas turbines was that,for something as efficient as a Diesel to be only 50% better means the turbines have come of age,I toured the "Normandy"last Thanksgiving and it was powered by Gas turbines that would get it up to flank speed in short order,I forget the specs,but it was impressive for something weighed that many Kilotons.
Back on the aircraft subject,50% better means it would take 50 gals to do what the other engine did with 75 gals,so maybe not that meaningful,not to mention the advantages in high altitude operation,I would hate to think what 80,000 HP OF Reciporcating engine would look like hanging off an airliners wings.
@Caddyman Correct. A steam engine without a condenser is about 5% efficient vs a diesel at 35% or so. You can’t put a condenser on a train, it’s just too bulky. And you have to make multiple stops for water without a condenser.
Cruise ships ad freighters use high efficiency large diesels that burn cheap residual oil. The power plant is relatively compact compared to a steam turbine with boiler and condenser.
But being an external combustion setup,means practically anything that burns can be used for heat.One Guy had a small boat at Lake MooMaw powered by "pineknots"via a local artisan built steam engine.A few early steam cars had condensing type engines,the readily availible cheap liquid easily handled ,energy dense,hydrocarbon fuel has spoiled us,especially for smaller apps(I suppose most powerplants and most nuclear subs are still steam driven(to turn the generators)steam will always be with us.
I suppose....most nuclear subs are still steam driven(to turn the generators)steam will always be with us.
From Wiki:
The Russian, US and British navies rely on steam turbine propulsion, while the French and Chinese ships use the turbine to generate electricity for propulsion (turbo-electric transmission).
The reduction gears from the turbines to the prop shaft are quite impressive:
There were some steam locomotives with condensers, used only in places where water was very, very scarce. In most places providing enough water was easier than supplying fuel, though it did sharply influence the routes railroads chose through desert areas. In the driest areas they used a second tender to carry more water.
In addition to a small number of steam turbine locomotives, there were also gas turbines, massive and massively powerful, but their inflexibility and thirst doomed them. Trains don’t do as much starting and stopping as cars, but the energy spent getting a train up a modest grade is far greater than pulling a train on level track. A gas turbine big enough to get a train up a grade would be very inefficient at all other times. In this sense a train is more like a car than a ship, and even they find big diesels attractive.
I suspect before pure electric cars predominate we’ll have future hybrids with very small engines keeping batteries charged, but relying on the batteries to drive an electric drivetrain. Right now we’re still sizing engines that are providing far more power than is needed to keep the batteries charged. The problem seems to be that a much smaller ice is inherently less efficient, so it’s worth putting in a larger engine even if it is not running most of the time. Toyota even increased the size of the engine in the current Prius to improve its gas mileage. If we can figure out how to make a truly fuel efficient very small engine we can build a really super car.
While Diesel is cheap it is attractive a very good substitute for diesel fuel can be made from coal and marketed for less then $1 USD GAL,while the crude is cheap and still flowing,alternatives will not make a major impact,due to the current hierarchy
.Many times here in the ridges it has been noted that smaller engines are not necessarily more fuel fuel efficient then a larger engine,its not so much the inherent efficiency of a larger engine,its the thing of matching the engine to the task,To get my Dakota up to speed probaly requires at least 2/3s throttle,were as the V8,would probaly require 1/2 throttle or less,now which engine would be using less fuel?The Caprices and Roadmasters would get 25-26 mpg cruising on the road toting around 4-5k# with a 350 cid engine so it amazes me that the manus still try to foist things on the public that are subpar,any drivetrain upgrade you buy a vehicle with around here will cost several thousand dollars more,over the so called “standard” engine(now is that really an option?).
@Mark.we know how to do it(its called a CRD) engine and the so called adibatic engine design was quitely allowed to slip into oblivion,to make a larger engine more efficient means to narrow its operating range to constant number,go watch any diesel powered piece of equipment when it throttles up,there is a large squirt of fuel going into the combustion chambers,an excavator is not a very efficient piece of equipment,because the oil flow depends on the engine speed and everytime you move the lever,the engine accelerates,accumulators would would really help this,but its not common practice(caterpillar has started developing “Hybrid"excavators said to be 25% more fuel efficient,havent kept up,so I dont know were this has went)
So there is always room for improvement,just like in housing construction simple things can mean a lot in terms of energy usage(and some of it depends on the human element)some convenience and comfort can be sacrificed. As Jim Marrs said"There is really not a population explosion,you coud settle all the earths inhabitants in Texas and give them an acre apiece” which is true in a way,we He didnt tke into into consideration was greed,ambition quarreling,some land is just not suited for people and the comfort level some people think they need to thrive.
I will postulate this,there are technologies that car makers posses right now,that will not showup for at least 5 yrs,after all,wouldnt the perfect automobile create mass unemployment?
“you could settle all the earths inhabitants in Texas and give them an acre apiece” – not true
Texas area is 268,581 sq mi (Wikipedia) or 1.7e8 acres. World population is 7.3e9.
dividing, that is 0.02 acres per person. Or 114 square yards, a square 32 feet on a side.
Didnt check it myself,thats what Jim Marrs said,but thanks for the correction,I may have gotten mixed up when he quoted the figures(an acre is 208.something on a side.ft that is{43560 sq ft})So each person could have a 1/50 th an acre?
He was trying to make the point there is still plenty of land availible) but I thank He was obscuring the real issue as to how many resources the average person would consume ,living an american lifestyle.
You are mostly correct but please double check your math,(I believe a sq yd equals 9 sq ft) you have got Me a bit confused,please point out where my arithmetic breaks down,I figure a.01 of an acre @43.56 sq ft x2= 97.2( 32 squared =1024 sq ft) are we talking about a different acre equivalent?No offense intended I’m just curious.
1/50 of an acre is hardly “plenty of land.” You’d need around 40 acres simply for food, timber and fuel for a family–especially in Texan land conditions. (I’m assuming self-sustaining, so no upping crop yields via synthetic fertilizers, unless you can make 'em on site, or trade with neighbors.)
kmccune, not clear what part of my math you find confusing. In more detail…
268,581 sq mi x (5280 ft/mi)² = 7.49e12 ft²
7.49e12 ft² / 7.3e9 people = 1025 ft²/person
√(1025 ft²) / person = a square 32 ft on a side
7.49e12 ft² x (1 acre/43,560 ft²) = 1.72e8 acre
1.72e8 acre / 7.3e9 people = 0.024 acre/person
didnt know Bill,didnt realise you were rounding down not familar with your notation either I.always used exponets the old fashioned way,didnt realize that how you express with standard keyboard(not that I really am concerned,I was just quoting Jim Marrs FWIW.
I would just multiply the sq miles by 640,to get the acreage in Texas,anyone can see after a little scrutiny and estimation,that the figures I quoted wasnt even close
@kmccune, gotta disagree with the bigger engine is more efficient argument. There’s a reason why the Corvette has cylinder deactivation, which transforms the engine from a V8 to a V4. A V4 requires a larger throttle opening than a V8 to achieve the same power level. Larger throttle opening equals lower pumping loss and higher efficiency.
A large engine can turn at a slower speed during high power operation and keeps itself from grinding into dust or grenade due to fatigue failure.
@CA,true,didnt think I was disagreeing with you,the larger engine has more surplus power and will move things with less throttle,that why I despise “standard engines”(which maybe cost the manufacturers $50 less to produce-give me the true option of engine choice)
I see what you mean about the pumping efficiency,my v6,burns as much gas as a v8 to achieve the same (maybe more,as it seems to strain) result then at top end you have less output(real slug) when you need the power the most,I expect the corvette at v4 mode plus lower weight and better aerodynamics will cruise easily at 70 mph,whereas my Dakota will not,another thing to consider with that vette,you could install a steep overdrive,and that thing would cruise at high speed just above idle with the throttle barely open,getting great mileage without cylinder deactivation.I heard that Chrysler was considering cylinder deactivation on the small Pentastar V6(that would have been a disaster,fortunately cooler heads prevailed)The engineers are good but,sometimes KISS is ignored,one of my brothers replaced the front stabilizer links on the Dakota yesterday,( for the second time in 87k miles)whilst I was doing other things I noticed how the front sheetmetal was attached to that vehicle(really weird engineering and no attempt was made at aerodynamics either,streamlining could have been easily accomplished to a certain degree)But I guess its easy to see how the domestic pecking order of vehicles was wrought,other then that its a good vehicle to go to Home Depot in.
The reason for using tall overdrive is to keep the engine lugging close to idle while cruising. This requires a large throttle opening and the opened throttle reduces pumping loss. A final drive this tall can be install in any car without damage to the engine. However, since your throttle is already opened, the only way to call for more power is to downshift, which apparently is distasteful to many drivers.
Note that the Chevy sonic with aa 1.4l engine cruises at 60 with 1.4k on the tach, probably with the throttle opened up. When you need more power, the turbo crams more air in there sooner than the driver can downshift