skippydiesel Posted January 27, 2019 Share Posted January 27, 2019 Hi All - This is not a topic I have any deep understanding about, so feel free to disagree but when you do please give rational reasons. A very learned friend of mine, just happened, as a part of general wide ranging conversation, to voice the opinion that jet (generic usage covering all forms of non piston powered aircraft) aircraft are probably the single worse generator of atmospheric pollution today, in particular passenger/freight services. He went on to say that the pollution generated by the tonnes/hr of aviation kerosene that is burnt, by the many thousands of aircraft airborne at any one time, is delivered straight into the upper levels of the atmosphere, where it can do the most damage. The popularity of the oversees/destination vacation has added to this, unspoken about (we are all culpable) man made fowling of our planet. What think you??? Link to comment Share on other sites More sharing options...
Swish Projects Posted January 27, 2019 Share Posted January 27, 2019 I think we leave the chickens and ducks out of this. 1 Link to comment Share on other sites More sharing options...
facthunter Posted January 28, 2019 Share Posted January 28, 2019 There are reliable figures out there on it.( CO2 and NOx.) I'm not sure it's at the figures your learned friend has conveyed to you, YET.. Fuel consumption of jet engines has improved a lot since the early ones. There's many conspiracy theories about jets secretly releasing chemicals in the upper atmosphere (which I would see as very unlikely to be happening and unlikely to be kept secret if it was happening). IF you calculate how much jet fuel it takes to get you to Europe and back It looks really bad. Flying is probably artificially cheap and too easy to do today, hence we probably do more than we should and can justify, on a need to do and a looking after the planet basis. I spent most of my working life up the front of a Commercial Jet, and I Iiked that, but hate being a passenger so I only get in one when I pretty much HAVE to.. Currently many airlines are having trouble making a profit, including some middle east ones. It's ALWAYS been a difficult Industry with high turnovers and low profit margins on turnover . Fuel costs are CRITICAL and prices a big risk to all operators. That's why if you aren't operating the Latest lightweight fuel sipping models you go out of business. Nev Link to comment Share on other sites More sharing options...
turboplanner Posted January 28, 2019 Share Posted January 28, 2019 Correct FH, I’m not sure of the emission standards, but there is plenty of video of 1959 Boeing 707s trailing black smoke compared with no smoke today. Link to comment Share on other sites More sharing options...
old man emu Posted January 28, 2019 Share Posted January 28, 2019 I wonder what the comparison is in the CO2 emissions of an ocean liner going between Sydney and Southhampton, and an airliner doing the Sydney Heathrow run. Link to comment Share on other sites More sharing options...
skippydiesel Posted January 28, 2019 Author Share Posted January 28, 2019 I wonder what the comparison is in the CO2 emissions of an ocean liner going between Sydney and Southhampton, and an airliner doing the Sydney Heathrow run. Yes indeed and not just the emissions think of the supplies to keep each passenger alive & well. It would be very interesting to have someone do the calculations/comparison. Link to comment Share on other sites More sharing options...
fly_tornado Posted January 28, 2019 Share Posted January 28, 2019 shipping things by ship is always the most efficient method of transport, especially if you ship from west to east Link to comment Share on other sites More sharing options...
Hargraves Posted January 28, 2019 Share Posted January 28, 2019 I,m by no means any sort of expert on this subject, but for my two(sense) worth it seems to me that most are almost completley missing the issue, (as in being in a forest but can,t find a stick) as already correctly stated jet engine efficency has vastly improved over the last 50 years espessially in power output and emissions control, but does anyone consider why this is the case overall, in both nature and engineering you still don,t get something for nothing, the amount of oxygen required to burn that fuel and produce that power is exponentially a much more serious problem that any form of polution generated by it. As a complete layperson In the eighties, as now, it was once simlpy explained to me by a very savvy pilot, that if we could view oxygen usage by high altitude jet engines in the same way we can view the contrails they make, the (skytubes) for each would be hundreds of times bigger for each engine than the contrails themselves. But then again I,m just a igorant storch pilot pickin on me tablet. Cheers hargraves Link to comment Share on other sites More sharing options...
johnm Posted January 28, 2019 Share Posted January 28, 2019 5,000,000 barrels of aviation gas a day - or thereabouts Link to comment Share on other sites More sharing options...
facthunter Posted January 28, 2019 Share Posted January 28, 2019 Basically the less fuel you burn the less oxygen used. The ratios are pretty constant but the efficiencies are vastly improved by running the system hotter with better blade design (cooling) and materials. Also variable incidence vanes and higher bypass ratios help too. The higher combustion temps might be more adverse with NOx Bypass air is not altered Cabin air is recycled (BAD for passengers) another efficiency increase.. Average cruise levels have increased too. Nev Link to comment Share on other sites More sharing options...
Litespeed Posted January 28, 2019 Share Posted January 28, 2019 If comparing the ship to aircraft, it depends on what we measure. If it is passengers then the plane will always win. Why? The ship is 99.99% not passengers by weight, it carries a massive bulk just for luxury, staff, food, grog, entertainment, pools, casinos. It is incredibly inefficient, however if it is airfrieght vs a cargo ship the opposite is true. Link to comment Share on other sites More sharing options...
skippydiesel Posted January 29, 2019 Author Share Posted January 29, 2019 If comparing the ship to aircraft, it depends on what we measure. If it is passengers then the plane will always win. Why? The ship is 99.99% not passengers by weight, it carries a massive bulk just for luxury, staff, food, grog, entertainment, pools, casinos. It is incredibly inefficient, however if it is airfrieght vs a cargo ship the opposite is true. Its possible that the resources needed/expended to maintaining an environment that will deliver passengers in good health,could be considered neutral - if they stay at home they might consume a similar amount of resources. Link to comment Share on other sites More sharing options...
Litespeed Posted January 29, 2019 Share Posted January 29, 2019 The need for food etc at home is irrelevant. It is the idea of moving such a massive climate controlled moving city across the plant for a tiny human weight fraction. It is a incredibly wasteful way to travel. 1 Link to comment Share on other sites More sharing options...
fly_tornado Posted January 29, 2019 Share Posted January 29, 2019 you can just imagine the amount of sewerage a cruise ship produces every day with everyone eating and drinking themselves stupid 1 Link to comment Share on other sites More sharing options...
facthunter Posted January 29, 2019 Share Posted January 29, 2019 You would need to drink a lot to get over the confinement and boredom. I wouldn't do it if YOU paid for it., for me. It must get addictive. I know people who do it all the time.. Sometimes the whole thing goes septic and everyone gets ill. Nev Link to comment Share on other sites More sharing options...
Downunder Posted January 29, 2019 Share Posted January 29, 2019 The time taken to travel and litres per person are relevant. (Litres per person per hour?) X thousand people on a cruise liner taking weeks Vs X hundred people on an airliner taking hours...... And regarding pollution, I guess the type of fuel matters too..... Is it any worse than one person driving their car back and forth to work everyday by themselves? Link to comment Share on other sites More sharing options...
facthunter Posted January 29, 2019 Share Posted January 29, 2019 Ships engines run on Bunker fuel which is just about pure crude oil. It's a lot cheaper than Avtur but much more polluting. Lot's of Sulphur, that forms strong sulphuric acid when burnt with hydrocarbons. Great stuff. Nev Link to comment Share on other sites More sharing options...
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