Air travel (possible n00b question)

Mike 1972

First off wasnt sure it this should come under "advice" or "policy" -apologies if Ive got it wrong.

Is there much difference in the efficiency (and emission) levels between jet and propeller based aircraft ?

If so is there any reason why the latter cant be promoted as a greener somewhat less environmentally unfriendly solution for short to medium haul travel ?

Or would longer journey times (less turnaround) and lower capacity (smaller aircraft but similar staffing levels) make it uneconomic ?

Occasionally Ive heard some people suggest a return to airships but safety concerns would probably rule out hydrogen (even though long metal tubes carrying tonnes of highly flammable liquid at hundreds of kilometres per hour dont worry anyone) while long term availability of helium has recently come into question.

Mahatma coat

From my understanding the Modern JEt engineis eficient due to Scale, a Turboprop probably burns a little less fuel per hour, but its not as fastandcant cary the same loads so overall on the comparasins of PEople moved in a specific timeperiod theJet wins out.

I too believe there may be some kind of solution with Blimps and Gliders for non time critical travel, come on lads if it cost the same to Fly to the Canaries on a plane or a blimp, the only difference being that you had to spend 3hours in a cramped seat or 30 hours in an opulant floating hotel, whichway would you begin your Holiday???

hurleronditch

Mahatma coat wrote: »

From my understanding the Modern JEt engineis eficient due to Scale, a Turboprop probably burns a little less fuel per hour, but its not as fastandcant cary the same loads so overall on the comparasins of PEople moved in a specific timeperiod theJet wins out.

I too believe there may be some kind of solution with Blimps and Gliders for non time critical travel, come on lads if it cost the same to Fly to the Canaries on a plane or a blimp, the only difference being that you had to spend 3hours in a cramped seat or 30 hours in an opulant floating hotel, whichway would you begin your Holiday???

But if you kit it out like an opulent floating hotel it means weight and the heavier it is, the more fuel needed. At the moment by a long way the most fuel efficient way of moving many people decent distances at relative speed, is by jet aircraft. New developments such as the dreamliner made from lightweight composites are really starting to reduce fuel burn.

Prop craft dont save on staff anyways as you need 1 cabin crew for every 50 passengers i think so 200 with 4 in a big plane or 4x50's in small planes makes no difference

Merch

Mike 1972 wrote: »

First off wasnt sure it this should come under "advice" or "policy" -apologies if Ive got it wrong.

Is there much difference in the efficiency (and emission) levels between jet and propeller based aircraft ?

If so is there any reason why the latter cant be promoted as a greener somewhat less environmentally unfriendly solution for short to medium haul travel ?

Or would longer journey times (less turnaround) and lower capacity (smaller aircraft but similar staffing levels) make it uneconomic ?

Occasionally Ive heard some people suggest a return to airships but safety concerns would probably rule out hydrogen (even though long metal tubes carrying tonnes of highly flammable liquid at hundreds of kilometres per hour dont worry anyone) while long term availability of helium has recently come into question.

I dont know how if you are unsure of the efficiency of one type of aircraft compared to another, you imagine a prop aircraft would be more efficient?
That makes me curious, anyway essentially turbo prob are jet aircraft, confused?? well most prop aircraft (large commercial ones) are powered by jets, yes they are, albeit of the turbo-shaft variety, they are turbine engines driving a prop like a jet drives a fan+ its thrust.
Turboprops would be better (generally) at short takeoffs/landings and over shorter distances. As all long distance commercial aircraft are turbo jets or actually turbo fans then I guess the companies that design build and operate them have already figured out they are more efficient in many ways, safety, reliability, cost, power and fuel consumption, otherwise they wouldn't be using them. I'd have guessed at that but given the aircraft industry is bult around it, i'd say it's a given.
Piston engines are only (generally) used in light aircraft. Also there are some big turboprop aircraft out there, comparable to turbo jets too so you would really have to compare perhaps two very specifc aircraft types from each stable.

Also you talk about airships, probably an evolutionary dead end as far as passenger/cargo carrying goes. Hydrogen gets a really bad, but in my opinion undeserved bad press, mostly due to the Hindenburg. I dont suggest you try dropping a blob of grease onto some spilled oxygen but am sure its online somewhere, you wont get the same reaction with hydrogen.
As for long metal tubes filled with highly flammable fuel, well the tube is filled with people and cargo (mostly), the wings are filled with fuel (mostly)
Contrary to what Bruce Willis can do with a zippo lighter, kerosesne (jet fuel) isnt that flammable, it is ignited under conditions of high pressure and high voltage.

Mahatma coat

I had an Idea about
GliderBlimps

lets saythat you want to fly from Dublin to Frankfurt

Currently yo hop in a 737 or A330 or somesuch Jet, it climbs to cruising sped and altitude but by the tim its goten to a level and efficient flight its time to land again, so the engine is only efficient for a fractionof the journey.

how about

Some Big Blimps and (powered)gliders

You go Dublin Airport, you shufle through the terminal and Board your designated Aircraft, but instead of hurtling down the Runway at ferocious acceleration and pulling the machine full tilt into the sky with the big engines you simply cut a few ropes and gracefully raise into the sky ina Blimp, once the blimp is at the correct height, Just guessin at this but does 6-8 miles sound right, you point it at Frankfurt,and split it into two pieces, Blimp and Glider, the Blimp vents/Cools the Gases and descends gracefully back to Dublin Airport, The pasengers are now Gliding/falling in their compartment and using the engines only when nescessary for course corrections and the like, whenit gers to Frankfurt it lands on the Runway like conventional Aircraft, when its time to go home Frankfurt link itup to one of their 'BlimpTugs'and repeat the process.

I'm sure these someway of controling theBlimps around the Airport with Electromagnets or somesuch.


Maybe a system where there is a permanant Sky platform for them to link up to before Glide seperation, or a system that dosent involve ditching theblimp half of the craft might work better for controll of the landing


The idea came to me when I was looking at those toy Planes from Nazaca.

Merch

Mahatma coat wrote: »

I had an Idea about
GliderBlimps

lets saythat you want to fly from Dublin to Frankfurt

Currently yo hop in a 737 or A330 or somesuch Jet, it climbs to cruising sped and altitude but by the tim its goten to a level and efficient flight its time to land again, so the engine is only efficient for a fractionof the journey.

how about

Some Big Blimps and (powered)gliders

You go Dublin Airport, you shufle through the terminal and Board your designated Aircraft, but instead of hurtling down the Runway at ferocious acceleration and pulling the machine full tilt into the sky with the big engines you simply cut a few ropes and gracefully raise into the sky ina Blimp, once the blimp is at the correct height, Just guessin at this but does 6-8 miles sound right, you point it at Frankfurt,and split it into two pieces, Blimp and Glider, the Blimp vents/Cools the Gases and descends gracefully back to Dublin Airport, The pasengers are now Gliding/falling in their compartment and using the engines only when nescessary for course corrections and the like, whenit gers to Frankfurt it lands on the Runway like conventional Aircraft, when its time to go home Frankfurt link itup to one of their 'BlimpTugs'and repeat the process.

I'm sure these someway of controling theBlimps around the Airport with Electromagnets or somesuch.


Maybe a system where there is a permanant Sky platform for them to link up to before Glide seperation, or a system that dosent involve ditching theblimp half of the craft might work better for controll of the landing


The idea came to me when I was looking at those toy Planes from Nazaca.

Ok, you're having a laugh, right?
Actually, I'm editing this reply, putting this and the following in, to frame an answer correctly I would really need to know what age you are? so are you 5-10, 11-20, 20-30 , I'm not trying to offend you but I need to know where I am aiming my answer.

Mahatma coat

Merch wrote: »

Ok, you're having a laugh, right?
Actually, I'm editing this reply, putting this and the following in, to frame an answer correctly I would really need to know what age you are? so are you 5-10, 11-20, 20-30 , I'm not trying to offend you but I need to know where I am aiming my answer.

https://www.youtube.com/watch?v=rGkseGFQLh4

Explain it to me like I'm 5

Merch

ok but I cant play the guitar or sing

Airships couldn't be used because it would take ages to get where you want and they would be at the mercy of the weather more so than current aircraft.
Also I'm sure blimps use helium (they do, look it up) as a means to float not hot air so heating or cooling isnt what you need to do, I think they dump helium at the end of a flight, however the gases used would need to be manufactured and compressed somewhere which requires energy and human input and from what I read there is only a limited amount of it available (it might be the most abundant element in the universe but the processes to manufacture it here are not that efficient.
The idea of using electromagnets doesnt sound practical in the least, they would also require energy and money to research.

Aircraft while being technically advanced also have a lot of features which are old and tried and tested, mostly aircraft structures have harked to the design of days not long after WW2 thats more than half the whole era of flight! Im not saying they are all that old, just the design of rivets and sheetmetals etc obviously it has come a long way from when it and airship travel were operated at the same time.
Airships lost

Mahatma coat

Merch wrote: »

ok but I cant play the guitar or sing

Thats fine, neithre canI :D

Airships couldn't be used because it would take ages to get where you want

Thats why I sugested they be use for Non Time critical aplications

and they would be at the mercy of the weather more so than current aircraft.

Dunno, the Zeplins could land on Targetmost of the time, given our advances inpropulsion This is a problem that can be overcome.

Also I'm sure blimps use helium (they do, look it up) as a means to float not hot air so heating or cooling isnt what you need to do, I think they dump helium at the end of a flight,

Boyles Law would still apply tho, so coolin ad Recompressing would be an option.

however the gases used would need to be manufactured and compressed somewhere which requires energy and human input and from what I read there is only a limited amount of it available (it might be the most abundant element in the universe but the processes to manufacture it here are not that efficient.

AvGas still needs to be manufactured for existing planes, so whats the problem manufacturing something that wont be burned to give off CO2

The idea of using electromagnets doesnt sound practical in the least, they would also require energy and money to research.

Its very practical if you think about it.

Aircraft while being technically advanced also have a lot of features which are old and tried and tested, mostly aircraft structures have harked to the design of days not long after WW2 thats more than half the whole era of flight! Im not saying they are all that old, just the design of rivets and sheetmetals etc obviously it has come a long way from when it and airship travel were operated at the same time.
Airships lost

Airships lost due to a Little bit of Bad publicity, the asscosiation with the Nazis and the Abundance of Douglas and Boeing Bombers/transport planes on the Market after the War. Simple as that, there was a Glut of cheap planes, thats what made the Plane the most popular mode of Air travel, they were cheap and plentiful, as you said yerself techology hasnt really come any further since the 60's Hell we've gone backwards withthe Scrapping of Concorde.

Mahatma coat

Check this Baby out
http://www.smh.com.au/travel/travel-news/future-of-air-travel-giant-floating-hotels-20100706-zyqq.html?rand=1278400742145

Merch

Mahatma coat wrote: »

Quote:
and they would be at the mercy of the weather more so than current aircraft.
Dunno, the Zeplins could land on Targetmost of the time, given our advances inpropulsion This is a problem that can be overcome.
Quote:
Also I'm sure blimps use helium (they do, look it up) as a means to float not hot air so heating or cooling isnt what you need to do, I think they dump helium at the end of a flight,
Boyles Law would still apply tho, so coolin ad Recompressing would be an option.
Quote:
however the gases used would need to be manufactured and compressed somewhere which requires energy and human input and from what I read there is only a limited amount of it available (it might be the most abundant element in the universe but the processes to manufacture it here are not that efficient.
AvGas still needs to be manufactured for existing planes, so whats the problem manufacturing something that wont be burned to give off CO2
Quote:
The idea of using electromagnets doesnt sound practical in the least, they would also require energy and money to research.
Its very practical if you think about it.

Quote:
Aircraft while being technically advanced also have a lot of features which are old and tried and tested, mostly aircraft structures have harked to the design of days not long after WW2 thats more than half the whole era of flight! Im not saying they are all that old, just the design of rivets and sheetmetals etc obviously it has come a long way from when it and airship travel were operated at the same time.
Airships lost
Airships lost due to a Little bit of Bad publicity, the asscosiation with the Nazis and the Abundance of Douglas and Boeing Bombers/transport planes on the Market after the War. Simple as that, there was a Glut of cheap planes, thats what made the Plane the most popular mode of Air travel, they were cheap and plentiful, as you said yerself techology hasnt really come any further since the 60's Hell we've gone backwards withthe Scrapping of Concorde. .

Im curious as to what background you come from or what your experience is that you would pose/post such things?? genuinely I am.

compared to aircraft of their time they probably were safe and Zeppelins weren't the only airships, commonly the ones by the german designer or german ones that came after, besides the little information I can find actually says German Zeppelins actually lost time for operation due to ground handling issues due to the size, compared to the mostly efficient turnaround of aircraft and simplicity for fewer people to operate while on the ground, airplane wins that round in my opinion.

Currently blimps use helium,I'm not sure why you think boyles law is relevant as its about changing volume and pressure under constant temperature? from what you had written previously it looked to me as if you assumed blimps heated air like a hot air balloon, so I mentioned they use helium, I'd have to look into it but I would say a greater consideration is that as a blimp rises air pressure drops, also its large surface area could heat up if in the sun or possibly even daylight, I wouldn't think the temp is constant. I think you are talking about ascending and descending?? work is being done if you cool or compress anything, the energy for that has to come from somewhere?

Avgas isn't used in the quantities jet fuel is, avgas is for piston engined aircraft, commercial aircraft burn kerosene jet fuel.
As for the problem with manufacturing something that wont be burned to produce CO2, you answered it yourself it has to be manufactured, that in itself creates CO2, there isn't a large ready available supply of helium and to build the infrastructure, well it would cost.
Jet fuel already has an establised infrastructure for production, it would probably be cheaper and it might even be greener, by the time you take into account the total carbon footprint of almost starting from scratch to manufacture on a global scale gases for blimps en masse.

I have thought about it (re electro magnets) it doesnt sound in the least bit practical, please explain this to me because, I would prefer to be sitting in a jet under power than blown off course into a building in a blimp under the power of electro magnets
despite the fact that a jet engine is producing its own power, is about maybe 60% or more efficient.
electromagnetic fields could disrupt things, aprt from the fact they have to get their energy from somewhere to, by the time energy got to the magnet, I think its effectiveness would be so low that the efficiency would be horrendus.

It was nothing to do with the Nazis? aircraft could outperform airships before WW2 even started, airships would have been very vulnerable to a determined enemy, they got bad press from the well known Hindenburg disaster, but it was not due to a glut of aircraft after the war, aircraft simply outperform airships.
I didnt say technology hasnt come any further since the 60's if anything it has come on leaps and bounds since WW2, probably moslty after the 60's when electronics were more available than before and becoming cheaper and cheaper, a lot of things have changed, engines & their performance, reliability and efficiency, certain things have stayed relatively constant, like aircraft structure, but that is changing now also, navigation (electronics) I mean what I said previously in relative term, you could be in a freshly overhauled and outfitted 747 from the 70's (if someone had the money to do it) and to the untrained eye, not really be able to tell to much of a difference, but if you were to get into a car of the same era, you definitely know about it, I meant comapred to alot of other manufactured goods such as cars, electronics aircraft havent changed as much as other things have, even though they have changed a lot in themselves, other things have progressed more rapidly.
Concorde was an aviation evolutionary dead end, honestly I'm not suprised you brought that up as you think airships are all that too :eek:

Airships will only have a role in the future if aircraft are not viable in some way, re fuel supply and even then I would hold any hopes of going back to some golden age.

Merch

Mahatma coat wrote: »

Check this Baby out
http://www.smh.com.au/travel/travel-news/future-of-air-travel-giant-floating-hotels-20100706-zyqq.html?rand=1278400742145

Hate to rain on your parade, but it says its a concept, they talk about designing the materilas to support its mass?

Mahatma coat

Yeah, and I'm talkin about Theoretical possibilities with Airships as well.

Jaysus its a good thing you werent around when The Wheel was invented, I can picture it now

Ah Lad theres no ned for expensive Research into this Circle concept of yours
Its a Dead end, nothing will come of it
Why cant you just Walk like everyone else



Fortunatley for Humanity there are People with Vision out there who Dare to Imagine things and Say WHY NOT

Merch

Mahatma coat wrote: »

Yeah, and I'm talkin about Theoretical possibilities with Airships as well.

Jaysus its a good thing you werent around when The Wheel was invented, I can picture it now

Ah Lad theres no ned for expensive Research into this Circle concept of yours
Its a Dead end, nothing will come of it
Why cant you just Walk like everyone else



Fortunatley for Humanity there are People with Vision out there who Dare to Imagine things and Say WHY NOT

excuse me?
I'm pointiong out why airplanes are preeminent over airships because you dont have a clue, youre talking about stuff that is incorrect like avgas and suggestions that prop aircraft are piston engined among others.Airships?
You sound like you are still in school or have never come across anything technical in your life.
I agree with challenging things which is why I said there may be a place for airships but it is only when for some reason aircraft are not viable.

I live in the real world not the land of sci fi comics

Mahatma coat

OK So I said AvGas instead of Aviation GradeKerrosene for Jet engines, it may not be technically corect, but Hey, I was only trying to expand on a point.

Where did I say a Turboprop had Pistons????

My Age or Schooling is irelevant to the situation, I was interested in having a discussion with the OP about the merits of Airships, not to have to deal with this level of Arrogance from some Armchair Expert.

I think Airships in some form or other will make a resurgence this century

Merch

Im no armchair expert, Id have allocated you that title. I am not being or attempting to be arrogant, that's your interpretation, I'm just saying you're wrong, if you weren't there'd be airships all over the place. Anyway as I have worked in aviation and it has been something of interest to me as long as I can recal, I think of the two of us I know significantly more about the subject.

When someone hails the next best thing, you have to look at it on its own merits, how does it stand up to what it will compete with.

You say airships will make a comeback this century, well thats a hell of a long time so you could be proved right as god knows what will happen in that time and what needs people might have, currently NO.

When I see blimps being guided in to land with electro magnets I'll come back and congratulate you myself.

by the by you threw the first insult regarding your wheel comment, that came across as an insult, you'll find when you insult someone you get the same in return.
good day

Mahatma coat

Hey donty start withthe Who threw the First insult, Cos I was Offended by your Age question.

Simple Rule, if You find yerself Typing
'I dont mean to Offend'
That generally indicates that You yourself see it as being offensive,
in that Situation, Dont Type it.

Corsendonk

Would Blimps be better employed as heavy lifters rather than passenger carries? I do vaguely remember reading an article that the germans were interested in using them as heavy cargo lifters.

Mahatma coat

I remember reading that article Too

Heres a bit about it
http://www.airshipinitiatives.com/heavy-lift/4526949604

it was being discussed as a posible means of transport for large industrial equipment across Africa and the like, where curently to get something to a mine you have to build the road first, and you run the risk of being ambushed at any point along it, the HLA would be able to float gracefuly overheadwith a few thousand tonnes of stuf danglin underneath.

djpbarry

Merch wrote: »

You sound like you are still in school or have never come across anything technical in your life.

Mahatma coat wrote: »

My Age or Schooling is irelevant to the situation...

Merch wrote: »

...you threw the first insult regarding your wheel comment, that came across as an insult, you'll find when you insult someone you get the same in return.

Mahatma coat wrote: »

Hey donty start withthe Who threw the First insult, Cos I was Offended by your Age question.

Simple Rule, if You find yerself Typing
'I dont mean to Offend'
That generally indicates that You yourself see it as being offensive,
in that Situation, Dont Type it.

I have a much more simple and effective rule - if you have an issue with a post, report it.

Let's keep the personal comments out of the discussion please.

djpbarry

On the subject of airships, I just came across this article in IEEE Spectrum which may be of interest:

Airships for the 21st Century

Long-duration, heavy-lift designs breathe new life into the world's oldest aircraft technology

http://spectrum.ieee.org/aerospace/aviation/airships-for-the-21st-century

I've just had a quick flick through it - some cool pictures in there. Haven't had a chance to read it in any detail just yet.

Mahatma coat

Interestin article, it would seem tyhat a lot of companies are researching Airships, the advantages laid out there in the article are fairly obvious really.

As Observation posts they would excell, also as missile platforms and obviously the heavy lift capacity I mentioned earlier.


Anyone see an episode of Dr Who where they jump into a paralel universe where Everyone who's anyone lives in an Airship

Capt'n Midnight

Jets fly higher than turboprops, there is less air resistance so they are more fuel efficient up there. On shorter trips turboprops would be more efficient. But since a jet is about twice as fast you only need half as many of them so a huge saving on resources.

Airships wouldn't be faster than trains and probably less effecient than electric trains.

And if airships go commercial don't expect car ferry like space to wander around in, it will be lots of seats, unless airships become cheap enough to carry freight with a side line in passengars

Mahatma coat

Eh, no one thinks that Airships could have a speed advantage, even over trains, but its the ability to Lift Massive objects or stay in the air for long periods thats really interesting, especially considering the simplicity of the infrastructure requirements to Deploy Airships, Trains need Rails, Trucks need roads Planes need runways, but everything required to 'Land' something with an Airship can be carried in the ship.

Capt'n Midnight

airships look very interesting for stuff that the Antanov 124 /224 currently do

loads too heavy / bulky to travel by existing roads between A and B and provide point to point delivery - you could build multistory appartments one by one in the factory and then bolt them in place

of necessity airships can't travel above the weather so flying time will be heavily affected by bad weather. - this means that time critical travel should be done by rail instead

one consideration would be an airship with limited independent endurance , where a ground vehicle provides most of the power / propulsion and anchorage. imagine you have an electricly powered airship with 30 minutes of batteries / generators / fuel cells operating off some hydrogen gas - you would save a lot of weight on powerplant and fuel

in places like africa / america / russia / australia where there are empty roads you could use a magnetic tow line, releasing when there were obstacles and re-engaging on the other side

in other places you could use microwave power transfer, airships have plenty of surface area for receiving and since you can get 50% efficiency on the transfer you could even have an electric train doing the uplink , so in effect you have an airship that can follow railway lines

as lighter thin film solar panels are developed they should become more feasible as power to weight ratio improves further http://en.wikipedia.org/wiki/Thin-film_solar_cell

it might even be possible to have enough power to keep such an airship in the sunlight above the clouds if was designed as a lifting body such that long distance travel was possible - but for reliability and speed they won't be able to compete with jet aircraft. They won't beat trains on speed or cost even if energy is free.

Mahatma coat

heres an interstin product to power the Airships
http://www.abc.net.au/tv/newinventors/txt/s3008638.htm