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Single Engine Airliners Of The Future?  
User currently offlineDHHornet From United Kingdom, joined May 2006, 252 posts, RR: 0
Posted (7 years 10 months 1 week 4 hours ago) and read 5141 times:

Single Engine Airliners Of The Future?

Will we in the future have a 737/A320 type (and bigger) single engine airliners flying?
New light biz jets have tidy designs based around a single engine. Could this work on a larger scale?

Why not? Engines are more reliable; Twins fly across the oceans now. Years ago it would have been as silly as suggesting single engines now. Why not have solar/electric/wind turbines powered very light engines, as back up if the main one stops. With just enough power for basic turns and straight and level flying?

Fuel of the future. I go with Hydrogen.

What do you think?

[Edited 2006-11-29 16:10:24]

52 replies: All unread, showing first 25:
 
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 1, posted (7 years 10 months 1 week 3 hours ago) and read 5133 times:

Not in the USA. Our regulations prohibit such a thing.

FAR § 121.159 Single-engine airplanes prohibited.

No certificate holder may operate a single-engine airplane under this part.


This "part" refers to Title 1 USC Part 121, which is titled "Operating requirements, Domestic, Flag, and Supplemental Operations" and it contains the rules under which our airlines operate.

Although today's jet engines are much more reliable than early ones, and especially early piston engines the issue is redundancy. In fact all important important components and systems must be redundant. I don't think in today's political or liability climate anyone would change this rule if they had the opportunity, and no matter the economic pressures.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineKukkudrill From Malta, joined Dec 2004, 1123 posts, RR: 4
Reply 2, posted (7 years 10 months 1 week 3 hours ago) and read 5130 times:

Yes you have twins flying across the oceans, but only if they are ETOPS-certified. A backup powerplant using an alternative energy source seems to me to be extremely unfeasible because (a) surely it won't generate enough power to keep the plane flying (b) during normal flight it would constitute very uneconomic deadweight, as opposed to a conventional twin where both engines earn their keep.


Make the most of the available light ... a lesson of photography that applies to life
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17054 posts, RR: 67
Reply 3, posted (7 years 10 months 1 week 3 hours ago) and read 5128 times:

I don't see it. It would introduce a single point of failure of tremendous proportions. Engine failures are rare but they still happen every now and then.


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 4, posted (7 years 10 months 1 week 3 hours ago) and read 5127 times:

There were some threads about this a few months back:

Hydrogen: Insufficient energy per volume. In an A380, half the hull would have to be fuel tanks to get the same range as a normal A380 running on kero. Now if you could compress hydrogen to the point where it became degenerate matter, then you might get somewhere.

Whether a single engine can be reliable or not is kind of moot. It wouldn't get certified. But ignoring the rules for a minute, where would you put an engine that size? You [i]could[/] mount it the same way that Tacit Blue's was, but history has shown that an S-duct is not the most efficient way to feed air to an engine.

Lastly, I expect that any secondary devices - solar-powered props or whatever - would not be sufficient to carry the plane very far, and would be dead weight for the 99.999% of the time that they weren't being used. If you're going to hump weight around, it might as well be worthwhile - like a second, working engine...

edit : cyselxid fingers

[Edited 2006-11-29 16:25:51]


Todos mis dominós son totalmente pegajosos
User currently offlineDHHornet From United Kingdom, joined May 2006, 252 posts, RR: 0
Reply 5, posted (7 years 10 months 1 week 3 hours ago) and read 5124 times:

Thanks all. I was really thinking in 20-30 years time. What will be the norm?

OK. I say the A340 and 747 will be last four engine airliners built. The future is the twin or ....?


User currently offlineOly720man From United Kingdom, joined May 2004, 6756 posts, RR: 11
Reply 6, posted (7 years 10 months 1 week 3 hours ago) and read 5120 times:

Quoting DHHornet (Thread starter):
Fuel of the future. I go with Hydrogen.

Or carbon neutral(ish) bio fuel. (Still got to process it.)

Single engine on a bigger plane? Unlikely. Main reason redundancy (and the rules #1 above). Reason 2; where to put it?

Biggest single engine plane is what? An2? And there have been no improvements on that.

Solar power is inefficient, space wise. You need a massive area of cells to generate any meaningful power and even that won't be enough to keep even a small airliner in straight and level flight.

http://www.pvresources.com/en/helios.php

The helios aircraft has a wing area of around 190m2, covered with efficient solar panels and they powered electric motors with total power of around 22kW. This wing area is around 50% higher than an A320 or B737. In one of the wind tunnels I use, a 50kW motor is needed to move air at around 50m/s through an area of around 1.2m^2.

A jet engine generates power in the 100s of kW. No easy replacement.



wheat and dairy can screw up your brain
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 7, posted (7 years 10 months 1 week 3 hours ago) and read 5120 times:

Quoting DHHornet:
The future is the twin or ....?

...The return of the tri-jet in some form or another. But I recently learned here that this is not likely, since the mission that the tri-jet fulfilled can now be handled by twins.

I don't think I'm sticking my neck out when I say that the future of conventional aviation probably belongs to the two-holer.



Todos mis dominós son totalmente pegajosos
User currently offlineDHHornet From United Kingdom, joined May 2006, 252 posts, RR: 0
Reply 8, posted (7 years 10 months 1 week 3 hours ago) and read 5116 times:

BAe146QT:
You are probably bang on with your comments. I just like to think that one day we will see as the norm a change from the 737/320 design.
But in reality this will be around for a very long time. I hope not and something more radical comes along?


User currently offlineDavid L From United Kingdom, joined May 1999, 9524 posts, RR: 42
Reply 9, posted (7 years 10 months 1 week 3 hours ago) and read 5107 times:

Quoting DHHornet (Thread starter):
Engines are more reliable

Maybe but even a 100% reliable engine would still be subject to birdstrikes and manitenance errors, for example.


User currently offlineDHHornet From United Kingdom, joined May 2006, 252 posts, RR: 0
Reply 10, posted (7 years 10 months 1 week 2 hours ago) and read 5102 times:

Some Intresting bits....

http://www.abovetopsecret.com/forum/thread205112/pg1


User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 11, posted (7 years 10 months 1 week 2 hours ago) and read 5090 times:

Quoting DHHornet:
You are probably bang on with your comments.

I'll cherish this, since it doesn't happen very often.

Quoting DHHornet:
I hope not and something more radical comes along?

Big-bang design changes tend to be influenced by need, or a major technological revolution. For example, most pre-WWII era aircraft I can think of didn't have swept wings... because they didn't need to.

The recent (say, since the 707 or DC-8) process of development seems to be very organic. It's all improvements to a trusted design. Some of them are radical enough - the glass cockpit comes to mind, which was made possible in part by cheap reliable computing power.

But for a major break from tradition, something really earth-shattering needs to happen. What, for example, would long-haul aircraft look like in 20 years' time if someone released a practical scramjet tomorrow which cost the same as a turbofan...?



Todos mis dominós son totalmente pegajosos
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 12, posted (7 years 10 months 1 week 1 hour ago) and read 5068 times:

For airliners to become single engine there would have to be a breakthrough, not in technology but in political courage.

To discuss this issue seriously you must overlook completely WHO makes laws in our societies. Can you honestly imagine a politician who seeks re-election for either himself or his party drafting a new regulation that removed any and all redundancy, backup, safety net from airliners? If you can imagine such a thing you need to watch politicians a while longer.

Never happen.
Not in ten thousand years.

Not unless the Constitution is amended first to remove ALL possibility of a citizen's being compensated for injuries or even bringing suit for same.

It is not a tech question. The technology has existed for this as long as airlines have existed. It is a question of law, of political courage and of pecuniary liability. Nothing else.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineBond007 From United States of America, joined Mar 2005, 5417 posts, RR: 8
Reply 13, posted (7 years 10 months 1 week 1 hour ago) and read 5051 times:

Quoting SlamClick (Reply 12):
imagine a politician who seeks re-election for either himself or his party drafting a new regulation that removed any and all redundancy, backup, safety net from airliners? If you can imagine such a thing you need to watch politicians a while longer.

Never happen.
Not in ten thousand years.

Not unless the Constitution is amended first to remove ALL possibility of a citizen's being compensated for injuries or even bringing suit for same.

It is not a tech question. The technology has existed for this as long as airlines have existed. It is a question of law, of political courage and of pecuniary liability. Nothing else.

I agree partly, but we'll be flying fare paying pax in single engine VLJs in the next few years, and you can fly now for hire under anything except Part 121 in a single engine aircraft.

You make it sound like everything has to be double/triple redundancy, but you can legally pay for a flight on a PC12 or Caravan today if you wish, and you've been able to for years....agreed under different regulations, but somebody making regulations thinks it's safe enough for me to fly Part 135 in a PC12 tomorrow.

As the thread starter mentioned, we'd had laughed at the fact not too long ago, if somebody told us we'd be flying 2-engine B737/757/767/777 across the Atlantic. No way would they let a twin jet fly across the oceans.

I agree that engine redundancy is a huge issue, but engine failures result in extremely few incidents/accidents, even in single engine aircraft.

Who know's what jet engine design will be like 10 years from now, or longer. I don't want to guess, but I know reliability increases year after year.


Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 14, posted (7 years 10 months 1 week 1 hour ago) and read 5043 times:

Quoting SlamClick (Reply 12):
It is not a tech question. The technology has existed for this as long as airlines have existed. It is a question of law, of political courage and of pecuniary liability. Nothing else.

While I agree with what you're saying there, I implicitly expanded the definition of "radical" beyond the OP's question of a single-engined airliner.

I was thinking more along the lines of a departure from the usual tube-with-fins-sticking-out-of-it, or perhaps even the application of some military technologies, like the removal of the vertical stab, (to reduce drag, not RCS...).



Todos mis dominós son totalmente pegajosos
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 15, posted (7 years 10 months 1 week ago) and read 5027 times:

Quoting Bond007 (Reply 13):
You make it sound like everything has to be double/triple redundancy

Do you grasp the mathematical difference between two engines and one?
In practical terms:

One engine - one engine failure = one forced landing at the most suitable piece of terrain within your gliding distance - if you can see the ground. This may be a gravel road across a hillside, it may be a tank farm or a subdivision or a mall parking lot.

Two engines - one engine failure = a normal landing at the nearest suitable airport in point of time, which may be, in the case of ETOPS more than three hours away. It may, indeed, be your original destination.


The difference is almost absolute, almost infinite.

Then there is the "one in a million" factor in air safety rulemaking. They allow for a one in a million event in aircraft design and operation. Events that are less common than that, a wing falling off in level, unaccelerated flight, or meteor strikes or an earthquake swallowing up every airport your plane can possibly reach for example need not be addressed in the interest of safety. The "one in a million" does not have to be precisely that in mathematical terms but that is an approximation.

So if an engine failure is a one in a million, then a second engine failure is one in a million millions.

1:1,000,000
or
1:1,000,000,000,000


Now there is the redundancy they allow for.

The redundancy difference between one engine and two is greater than the difference between a two engine airplane and a thousand-engine airplane.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 16, posted (7 years 10 months 1 week ago) and read 5019 times:

Quoting SlamClick (Reply 15):
So if an engine failure is a one in a million, then a second engine failure is one in a million millions.

Very true, but what about cases like the gimli glider or the Air Transat A330?

 duck 
 Big grin


User currently offlineDHHornet From United Kingdom, joined May 2006, 252 posts, RR: 0
Reply 17, posted (7 years 10 months 1 week ago) and read 5011 times:

Quoting BAe146QT (Reply 11):
I'll cherish this, since it doesn't happen very often

Make the most of it!

Quoting Bond007 (Reply 13):
As the thread starter mentioned, we'd had laughed at the fact not too long ago, if somebody told us we'd be flying 2-engine B737/757/767/777 across the Atlantic. No way would they let a twin jet fly across the oceans.

I agree that engine redundancy is a huge issue, but engine failures result in extremely few incidents/accidents, even in single engine aircraft.

Who knows what jet engine design will be like 10 years from now, or longer. I don't want to guess, but I know reliability increases year after year.

Yes exactly!


I guess I should of said originally is: How long will airliners remain looking like 7*7s AND A3*0s?
Maybe we are stuck with the aerodynamic shape of such aircraft for along time. A bit like road cars. Gone are the days of variation?


User currently offlineDavid L From United Kingdom, joined May 1999, 9524 posts, RR: 42
Reply 18, posted (7 years 10 months 1 week ago) and read 5006 times:

Quoting FLY2HMO (Reply 16):
Very true, but what about cases like the gimli glider or the Air Transat A330?

Smileys duly noted but, for the sake of completeness, ten engines aren't going to help in cases like that.  Smile


User currently offlineBond007 From United States of America, joined Mar 2005, 5417 posts, RR: 8
Reply 19, posted (7 years 10 months 1 week ago) and read 5001 times:

Quoting SlamClick (Reply 15):
Do you grasp the mathematical difference between two engines and one?

Yes, physics major  Wink

We can talk math all we like, but like I said, we allow fare paying pax to fly in 9 seat PC12s today ....it's perfectly legal and those who wrote the Part 135 and Part 91 rules think that it's OK for 9 people to fly commercially in a single engine aircraft under certain rules. FAA regs are amended continously to keep up with the latest developments, and will continue to do so.

Correct me if I'm wrong, but with 2 engines you're also twice as likely to have one engine fail, than with a single engine, correct?  Wink

I'm not saying it's going to happen, but it'll hardly be a "breakthrough in political courage" if/when it does.

A bigger problem might be convincing the public it's safe!


Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineDHHornet From United Kingdom, joined May 2006, 252 posts, RR: 0
Reply 20, posted (7 years 10 months 1 week ago) and read 5001 times:

Quoting SlamClick (Reply 15):
Do you grasp the mathematical difference between two engines and one?
In practical terms:

One engine - one engine failure...

The chances are higher you will have a car crash on the way to the airport, win the lotto, or drop dead?
 wink 


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 21, posted (7 years 10 months 1 week ago) and read 4994 times:
AIRLINERS.NET CREW
DATABASE EDITOR



It seems that most of this discussion has revolved around passenger ops.....I wonder if, sometime in the next 30+ years, the lack of redundancy in large-airplane single-engine ops will be considered an acceptable risk with regard to cargo ops. If most of the flight path is over water and unpopulated terrain, such operations would endanger few people on the ground.



2H4





Intentionally Left Blank
User currently offlineBond007 From United States of America, joined Mar 2005, 5417 posts, RR: 8
Reply 22, posted (7 years 10 months 6 days 23 hours ago) and read 4979 times:

Quoting 2H4 (Reply 21):
an acceptable risk with regard to cargo ops.

Well, what FAR part are the Fedex Caravans operated under?
Is that restricted by aircraft weight, or is it just that a Caravan is the largest single engine aircraft out there for such use?

I guess, what FAR restricts a Caravan being 4 times as big as it is now, and still be used for cargo? ...of course, aircraft design restricts it...but assuming you can make a single-engine aircraft that size.

Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineDavid L From United Kingdom, joined May 1999, 9524 posts, RR: 42
Reply 23, posted (7 years 10 months 6 days 23 hours ago) and read 4961 times:

Quoting Bond007 (Reply 19):
Correct me if I'm wrong, but with 2 engines you're also twice as likely to have one engine fail, than with a single engine, correct?  Wink

But the important odds are those of being left with fewer engines than required, regardless of how many you started with.  Smile


User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6461 posts, RR: 54
Reply 24, posted (7 years 10 months 6 days 21 hours ago) and read 4928 times:

Quoting Oly720man (Reply 6):
A jet engine generates power in the 100s of kW. No easy replacement.

Oh yes, many many 100s of kW.

It is not easy to convert thrust into power, but one way is to calculate the shaft power delivered to the fan and add the percentage of thrust delivered by the core.

That way a B744 taking off relies on 5-600 MW (MegaWatt) power. And something like 100 MW for cruise.

Thats also pretty consistent with gas turbines on ships. For instance Rolls-Royce claims around 75 MW continuous power from one shipborne RR Trent.

Quoting Oly720man (Reply 6):
Solar power is inefficient, space wise. You need a massive area of cells to generate any meaningful power and even that won't be enough to keep even a small airliner in straight and level flight.

Right. Very right! With the sun at zenith on a clear sky a solar powered B744 with all its upper surfaces covered with solar panels would be more underpowered than an Airbus 340. It would need roughly 10,000 to 20,000 times more power to get off the ground. I wonder how many acres of solar panels that would be.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
25 Post contains images Starlionblue : And what is the 380? Chopped liver? Sure. However large jets (currently those larger than 400 pax) will for economic reasons served by quads since th
26 Post contains images 2H4 : I'm still holding out for the return of 1000-foot long luxury zeppelins, complete with staterooms, cigar parlors, crushed velvet furniture, and a pia
27 Post contains images Lightsaber : I'm going to say no. Why? First rule of aviation engineering: Never be the lead story on CNN While in flight shutdowns are becoming rare, they still h
28 Post contains links Bond007 : Not sure where you got that statistic from. Even 'historically' , out of the 2 studies I have on-hand, the total for ALL mechanical failures (not jus
29 SlamClick : There is one type of accident where two engines may appear to degrade overall safety. That is underpowered, overloaded light twins flown by an amateu
30 BAe146QT : That would require separate designs for cargo and passenger aircraft. To me, that imples a lack of commonality which I believe in turn would; 1) Incr
31 Prebennorholm : Just one simple question, which doesn't need an answer: Are there any mx people out there who would want to work on an engine of a single engined airl
32 Post contains images KELPkid : Yes, but I'd imagine that Fedex, UPS, and DHL want reasonable assurances that their cargo makes the destination too. For a cargo bird, 1 vs. 2 engine
33 Post contains images 2H4 : Clearly, the ultimate solution is to build a single-engine widebody with bird-filled pods mounted on each wing. 2H4
34 Post contains images KELPkid : Light twins, however, have checkered safety records due to varying abilities of light twin pilots to manage Vmc (much closer to cruise speed and/or t
35 Post contains images KELPkid : Don't make that pod out of Aluminum or Glare, lest you find out the corrosive effects of bird excrement mixed with bird urine...
36 Post contains images Lightsaber : True... very true as you and KELPkid noted. Hence the comment "2nd engine to take the plane to the crash location." While I agree with your numbers,
37 Kl671 : If I remember correctly, FAA rules mandate that single engine aircraft have to have a very low stall speed so they can land safely on the local golf
38 Bond007 : Correct, but I believe there are waivers for certain conditions...I think one of the VLJs has a higher stalling speed, and some kind of waiver. .....
39 SlamClick : Do you have a reference for this? Regulation number?
40 Vzlet : I believe Kl671 and Bond007 are referencing the Part 23 61-knot requirement, but that only applies to "Normal, Utility, Acrobatic, and Commuter Categ
41 Lemurs : You can never have a 100% reliable piece of technology, espcially one that involves high temperatures, high speeds, and moving parts. Therefore, as lo
42 Pelican : There is a similar question I have: will we see one pilot airliners in the foreseeable future? I don't mean on long range flights where one pilot woul
43 Post contains images DHHornet : Yep! I'll go with that! Some of you should use your imagination more, and you should never, say never! Do you really know what technology will bring
44 SlamClick : It might be considered the "air time" rule: A crash that kills a hundred people gets a lot more television "air time" than does one that kills ten. S
45 Cloudy : This has been discussed to death... and Slamclick is probably right. The economic benefits of going from 2 engines to one are not enough to overcome e
46 BoeingOnFinal : This discussion can be compared to "will the planes in the future be fully automated and have no pilots?". Never gonna happen :p You can never say nev
47 747400sp : This would be dangerous, but if there was a very good back up system it could work. It would likely be a short body version of the CRJ 200/700/900. Th
48 2H4 : Why? It would be no safer. 2H4
49 SlamClick : As the saying goes: I want to look to my left and see nothing but engines, look to my right and see nothing but copilots.
50 David L : ... and look down and see nothing but mattresses.
51 Post contains images Starlionblue : Every time I think I'm cynical, Captain Click is there to show me I'm not cynical enough. ... or logical enough. Absolutely never say never. There ma
52 Bond007 : Well, I see exactly the same arguments for one pilot and one engine ... except that in term of reduncancy arguments, since over 55% of accidents are
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