Wind Powered Ships 2

[TugboatEng]

Augmented, maybe.

https://gcaptain.com/first-wind-assisted-supertanker-delivered-in-china/

It even has a real number, 9.8% reduction in fuel consumption. A typical tanker will consume ~500-600 bbls of fuel per day so that's no trivial number.

Alas, there is little interest as it's not "zero".

 

[dik]

I understand that fuel for ships is really 'ugly' stuff; is that correct?

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[itsmoked]

America's Cup Wings. When will they be going hydrofoil?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[TugboatEng]

Ships burn a range of fuels including marine gas oil, marine diesel oil, intermediate fuel oil, heavy fuel oil, and residual marine. Sulfur is the primary listed pollutant though there are others that aren't listed. The big issue around marine engines is that they're built for efficiency which means high cylinder pressure/temps. Marine engines and boilers make a lot of NOx emissions. We called it the brown efficiency haze when you had your boiler tuned just right.

 

[dik]

Largely depends on the type of power they require, and the efficiency of hydrofoil copared to conventional floatation, I suspect.

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

So, it can be real ugly stuff...

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[TugboatEng]

The Bunker C of yesteryear has long been obsolete. The closest comparable fuel would be IFO 380. The worst fuel I have seen is RMK770. That's residual marine, 1010 specific gravity, 770 centistokes.

 

[IRstuff]

Based on my limited experience in only cruise ships, they seem to burning some form of diesel, based on exhaust fume smell. And as with diesel trucks, lots of black, sooty, exhaust when getting going from a dead stop.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

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[hendersdc]

Personally I always found the rotor sails very interesting.

[URL unfurl="true"]https://www.norsepower.com/[/url]

 

[enginesrus]

Wind powered ships? Back to the good old sails I guess. Just like jet planes need to go back to propellers and pistons, much less fuel wasted.

 

[rb1957]

why do you think jets waste fuel (compared to props) ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[LionelHutz]

He thinks airlines are so dumb they don't realize they are flying planes that are very fuel inefficient.

 

[SwinnyGG]

Strap in, here we go

 

[btrueblood]

I mean, turboprops are pretty miserly on fuel consumption...but they run on turbines, not pistons.

edit: but props have a lower best-efficiency speed than jets, so for longer distances, turbofans give better efficiency. The linked page helps:

https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Propulsive_efficiency

It all comes down to $ per passenger-mile, and fuel cost is only part of the equation (airport operating costs, crew salaries and rest schedules, available routes to available airport slots...). And the biggie: nobody prefers slower, noisier flying experiences unless they have to. Like others mentioned, there are a lot of smart people trying to work the variables and win the game in commercial aviation, and very few of those are looking at piston powered aircraft engines.

 

[enginesrus]

There have been and still are standard non swept wing planes with piston power that travel very close to jet speeds and altitudes.
With proper aerodynamics of now, and 50% plus efficient piston engines using jet fuel, the fuel consumption of aircraft would drop dramatically.
Jets are not the future anyway, there can't be a battery powered jet. And when the airlines have the choice of an electric motor turning the propeller
and a huge Li ion battery pack, that is not allowed to be shipped on an aircraft in the first place. That will make those pistons look real good.
Kind of like returning ship's to wind power. Its regression all the way.

 

[btrueblood]

"very close to jet speeds and altitudes" - uh, no. 400 mph tops and 28000 ft., whereas jets are in the 500-600 mph range, >40,000 ft. Comparing the Constellation to a modern 787.

"Jets are not the future anyway"
Yes, props may dominate in the future, as you point out you can probably more easily hybridize a prop with an electric motor, though there are more and more geared-fan "jets" these days so we shall see. The economics aren't quite there yet for hybrids.

"proper aerodynamics of now" - meh, maybe CFD helps a few percent at lower speeds, but a lot of the heavy lifting for sub-400mph wings/controls got done in WW2.

"That will make those pistons look real good."
If piston engines are so wonderful, why do all the smaller commuter planes, and even some of the larger 12-passenger float planes use turboprops then? Decent efficiency (>40%), lower maintenance (3,000-6,000 hours between overhauls vs. 1000-2000 hrs. for pistons) (edit: also reliability, but that is at least partially baked into the MTBH numbers...but no way are you taking a 2-engine piston prop airliner on long flights over water with current FAA regs) and hp per pound. Nobody is talking putting a Wasila diesel on an airliner, that's just too much dead weight, any efficiency increase gets wiped out by having to lift the extra pounds. People are still using DC-3's, but you typically see them running turboprops on them, because they can put out more power with less weight (than the radials they replaced) which means more payload per run. Saw a recent article that talked about how the Union Pacific railroad developed gas turbine locos - because they could deliver 3-4x more horsepower than similar sized diesels. Yes, even in an automotive application where weight is valued (for traction), turbines gave an advantage. And they ran them for some 14 years, even though they had their issues (sucking all the air out of tunnels, roasting birds in flight with 800F exhaust blast) - because they could run them on heavy residual oil at a cheaper ton/mile freight cost than the Big Boy steamers or the diesel-electrics. They only stopped when refineries got better at cracking the heavy residue oils and upgrading them, and the cost of the heavy oils rose, and they figured out ways to efficiently run multiple linked locos.

It's all about the money, and you certainly don't know enough about airline economics (I sure as hell know I don't and I have a Masters in Aeronautical Engineering) to make a convincing argument here.

 

[enginesrus]

The why do they use turbines? is the phasing out of aviation gasoline and lack there of thus high prices. And lack of a modern recip engine capable of burning kerosene(jet fuel), large ones last produced in the early 1960's and only use leaded gasoline.

 

[SwinnyGG]

I know I'm wasting my time here but...

Large piston power for aircraft stopped being a thing because large piston technology was surpassed... not because they stopped making avgas.

What you don't seem to understand in these threads - there's been more than one at this point that brings this up and you either haven't absorbed it or don't understand it - is that best efficiency speed matters, a lot.

There are cases where a particular large piston engine could surpass the pure thermal efficiency of a turbine. That doesn't matter much, because a piston engine running at 50% efficiency in an aircraft flying at 400 kn still burns a lot more fuel than a turbine running at 40% efficiency but flying at 600 kn over the same route.

An aircraft is a system. Just because a particular piston engine can be more thermally efficient than a particular turbine can at a certain point of operation, does not mean that piston engine is the most efficient possible solution in the real world when all factors are accounted for.

Airlines are extremely cost sensitive. Extremely. And fuel is one of their largest fixed costs. If there were savings to be had, you'd be seeing a bunch of lycoming and rotax powered aircraft. You don't see that, because there isn't any savings to be had. It really is that simple.

 

[dik]

thanks Swinny...

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[LionelHutz]

SwinnyGG - ya most likely a complete waste of time.

Since passengers buy the tickets, airlines will break it down to expected number of passengers on a route and pick the plane that uses the least fuel per passenger. Of course, the plane has to be capable of travelling the route distance.

The stretched versions of the same plane are considered more efficient by the airlines simply because they carry more passengers.