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Topic: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-11-29 15:59:29 and read 5044 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]

Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-11-29 16:16:07 and read 5036 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: Kukkudrill
Posted 2006-11-29 16:19:46 and read 5033 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: Starlionblue
Posted 2006-11-29 16:20:31 and read 5031 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: BAe146QT
Posted 2006-11-29 16:23:35 and read 5030 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]

Topic: RE: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-11-29 16:29:16 and read 5027 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 ....?

Topic: RE: Single Engine Airliners Of The Future?
Username: Oly720man
Posted 2006-11-29 16:33:20 and read 5023 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: BAe146QT
Posted 2006-11-29 16:35:17 and read 5023 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-11-29 16:38:39 and read 5019 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?

Topic: RE: Single Engine Airliners Of The Future?
Username: David L
Posted 2006-11-29 16:53:30 and read 5010 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-11-29 17:06:27 and read 5005 times.

Some Intresting bits....

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

Topic: RE: Single Engine Airliners Of The Future?
Username: BAe146QT
Posted 2006-11-29 17:26:33 and read 4993 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...?

Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-11-29 18:06:55 and read 4971 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: Bond007
Posted 2006-11-29 18:40:30 and read 4954 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

Topic: RE: Single Engine Airliners Of The Future?
Username: BAe146QT
Posted 2006-11-29 18:57:59 and read 4946 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...).

Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-11-29 19:20:27 and read 4930 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: FLY2HMO
Posted 2006-11-29 19:33:44 and read 4922 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

Topic: RE: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-11-29 19:45:47 and read 4914 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?

Topic: RE: Single Engine Airliners Of The Future?
Username: David L
Posted 2006-11-29 19:49:30 and read 4909 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

Topic: RE: Single Engine Airliners Of The Future?
Username: Bond007
Posted 2006-11-29 19:53:00 and read 4904 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

Topic: RE: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-11-29 19:53:19 and read 4904 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 

Topic: RE: Single Engine Airliners Of The Future?
Username: 2H4
Posted 2006-11-29 19:57:58 and read 4897 times.



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


Topic: RE: Single Engine Airliners Of The Future?
Username: Bond007
Posted 2006-11-29 20:28:38 and read 4882 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

Topic: RE: Single Engine Airliners Of The Future?
Username: David L
Posted 2006-11-29 21:01:30 and read 4864 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

Topic: RE: Single Engine Airliners Of The Future?
Username: Prebennorholm
Posted 2006-11-29 22:17:59 and read 4831 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.

Topic: RE: Single Engine Airliners Of The Future?
Username: Starlionblue
Posted 2006-11-29 23:15:03 and read 4833 times.

Quoting DHHornet (Reply 5):
OK. I say the A340 and 747 will be last four engine airliners built. The future is the twin or ....?

And what is the 380? Chopped liver?  Wink

Quoting BAe146QT (Reply 7):
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.

Sure. However large jets (currently those larger than 400 pax) will for economic reasons served by quads since the cost of developing larger engines increases exponentially while corresponding market size decreases. The "large jets" boundary will continue move outwards as it has in the past. A few decades ago, 250 pax was a definite quad. Now it is a definite twin.

Quoting SlamClick (Reply 12):
For airliners to become single engine there would have to be a breakthrough, not in technology but in political courage.

Indeed.

Quoting SlamClick (Reply 15):
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.

Agreed.

Quoting FLY2HMO (Reply 16):
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?

Well, as you know (saw the smilie) some incidents/accidents are unaffected by the number of engines.

Quoting 2H4 (Reply 21):
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.

Or perhaps zeppelins with one engine?

Topic: RE: Single Engine Airliners Of The Future?
Username: 2H4
Posted 2006-11-29 23:29:04 and read 4921 times.




Quoting Starlionblue (Reply 25):
Or perhaps zeppelins with one engine?

I'm still holding out for the return of 1000-foot long luxury zeppelins, complete with staterooms, cigar parlors, crushed velvet furniture, and a piano bar.

Ah yes....it will be the sophisticated, gentleman's way to travel....  Wink



2H4


Oh....and we'll use helium....not hydrogen....


Topic: RE: Single Engine Airliners Of The Future?
Username: Lightsaber
Posted 2006-11-30 02:41:38 and read 4884 times.

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 happen. How can you prove they wouldn't ever happen?  scratchchin 

Don't get me wrong, for VLJ's, I love the idea of a single engine jet. But its one thing to lose a few golfers on an excursion; its quite another to loose 100+ people. One is like a bad car accident. It happens. We're conditioned to accept it. Loss of major life? Ugh uh...

Let's put it this way, which one ends up on CNN?

Quoting SlamClick (Reply 1):
Not in the USA. Our regulations prohibit such a thing.

FAR § 121.159 Single-engine airplanes prohibited.


 checkmark 

Quoting Starlionblue (Reply 3):
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.

While we joke in the areospace field that the 2nd engine is there to take the plane to the site of the crash, the reality is it provides a tremendous safety cushion.

Quoting Starlionblue (Reply 25):
Quoting DHHornet (Reply 5):
OK. I say the A340 and 747 will be last four engine airliners built. The future is the twin or ....?

And what is the 380? Chopped liver?

Its built?  duck 
just kidding...

Quoting Starlionblue (Reply 25):
Well, as you know (saw the smilie) some incidents/accidents are unaffected by the number of engines.

Very true. But historically, about half of all crashes have been due to engine failures. Do you want to vote for a dramatic risk increase?

Try to buy that insurance... Even with a regulation change, I doubt that the insurance companies will buy the idea...

Besides, the engine out climb test would be *really interesting.* (Required as part of airframe certification...)  duck 

Lightsaber

Topic: RE: Single Engine Airliners Of The Future?
Username: Bond007
Posted 2006-11-30 03:29:13 and read 4860 times.

Quoting Lightsaber (Reply 27):
Very true. But historically, about half of all crashes have been due to engine failures. Do you want to vote for a dramatic risk increase?

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 just engine), is highest 17%, and that's from 1959 or something, when engine reliability is not as it is today.

In the most recent Boeing study of commericial accidents from 1987 to 2005, the percentage of crashes related to powerplant (they do specify), is 6%.

http://www.boeing.com/news/techissue...desh%20Airlines%20DC-10%20crash%22

I assume that percentage will only get smaller.

The largest cause of accidents is pilot error, around 55%, and this is main concern for insurance companies. Once the aircraft is certified, the heaviest insurance restrictions are on pilot training, single vs dual, and hours.

There's a line somewhere between a bigger version of the PC12/Caravan, and something that than carry 100 pax.

10 people can legally fly commercially in a single engine turboprop ...could you have envisioned this 20 years ago?


Jimbo

Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-11-30 03:51:49 and read 4868 times.

Quoting Lightsaber (Reply 27):
the reality is it [the second engine] provides a tremendous safety cushion.

There is one type of accident where two engines may appear to degrade overall safety. That is underpowered, overloaded light twins flown by an amateur or a weak professional pilot. The classic VMC crash where the remaining engine was asked to do something it could not.

I've had, to the best of my recollection, seven engine failures.

4 in singles resulting in two restarts and two forced landings, one of them off-airport.

2 in four-engine jets which were not particularly dangerous. One inflight, with progressive damage finally making the engine inoperable and one rather dramatic seizure on takeoff roll, resulting in an RTO from about eighty knots.

1 in a two engine jet which resulted in a landing at the nearest suitable airport which happened to be my destination. Only one passenger even knew we'd lost an engine and that is because he was a deadheading pilot familiar with the equipment.

Let me tell you something about passengers.

Passengers are not airinersDOTnet members. They know nothing and care even less about airplanes. They just want to be in Kansas City in two hours instead of nine. Don't tell these people that this hypothetical new type of engine will never fail. They all know their car breaks down, their watch has stopped and their toaster has quit working. Machines fail.

Know what? They are not wrong.

Now, a few more related points:


• Elected officials are mostly lawyers. They will not even speak in paragraphs but limit themselves to sound bytes.
• No government official ever got in trouble for saying no.
• Someone sued McDonalds because the "hot" coffee she ordered was hot.
• The crash of a 6-place airplane makes local news for a day, the crash that kills a hundred people gets shown over and over on TV.
• No one but the members here remember a Cessna Caravan crash, but people still question the safety of the DC-10 because of a crash twenty years ago and the maintenance at one really good airline because of a crash six years ago.
• When there is a lawsuit over a plane crash the US Government is often sued as well.


But hey, someone might be so persuasive that they could convince people that they can bet their lives, their children's lives on ONE engine.

But I have money to bet that it will not happen in my lifetime except where it exists now - on itty bitty airplanes operated mostly by small companies that could be folded up in bankruptcy before a court date could be set and without triggering a Congressional investigation.

But I could be wrong.

Topic: RE: Single Engine Airliners Of The Future?
Username: BAe146QT
Posted 2006-11-30 13:03:06 and read 4768 times.

Quote:
.....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.

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) Increase the cost of mx., in the case of a mixed cargo/passenger airline.

2) Increase the price of production across the range for the manufacturer.

Quote:
Oh....and we'll use helium....not hydrogen....

You might want to make sure you don't paint the envelope with the equivalent of rocket fuel while you're at it.

Topic: RE: Single Engine Airliners Of The Future?
Username: Prebennorholm
Posted 2006-11-30 21:31:51 and read 4708 times.

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 airliner?

Topic: RE: Single Engine Airliners Of The Future?
Username: KELPkid
Posted 2006-11-30 23:08:35 and read 4676 times.

Quoting 2H4 (Reply 21):
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


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 engines might mean the difference between taking a swim in the drink vs. diverting to an alternate.

Just my  twocents 

Topic: RE: Single Engine Airliners Of The Future?
Username: 2H4
Posted 2006-11-30 23:11:41 and read 4676 times.




Quoting KELPkid (Reply 32):

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 engines might mean the difference between taking a swim in the drink vs. diverting to an alternate.

Clearly, the ultimate solution is to build a single-engine widebody with bird-filled pods mounted on each wing.  duck 



2H4


Topic: RE: Single Engine Airliners Of The Future?
Username: KELPkid
Posted 2006-11-30 23:18:01 and read 4671 times.

Quoting Lightsaber (Reply 27):
While we joke in the areospace field that the 2nd engine is there to take the plane to the site of the crash, the reality is it provides a tremendous safety cushion.

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 typical approach speeds) and/or single engine inoperative flight...also, many light twins have rather low single engine service ceilings...problems Jets don't suffer  Wink It also takes monster amounts of force to hold rudder against the dead engine...

Topic: RE: Single Engine Airliners Of The Future?
Username: KELPkid
Posted 2006-11-30 23:25:47 and read 4670 times.

Quoting 2H4 (Reply 33):
Clearly, the ultimate solution is to build a single-engine widebody with bird-filled pods mounted on each wing. duck



2H4


Don't make that pod out of Aluminum or Glare, lest you find out the corrosive effects of bird excrement mixed with bird urine...  Wink

Topic: RE: Single Engine Airliners Of The Future?
Username: Lightsaber
Posted 2006-12-01 02:37:59 and read 4615 times.

Quoting SlamClick (Reply 29):
There is one type of accident where two engines may appear to degrade overall safety. That is underpowered, overloaded light twins flown by an amateur or a weak professional pilot. The classic VMC crash where the remaining engine was asked to do something it could not.

 rotfl  True... very true as you and KELPkid noted.

Hence the comment "2nd engine to take the plane to the crash location."  Wink

Quoting Bond007 (Reply 28):
Not sure where you got that statistic from.

While I agree with your numbers, I disagree with many of the crashes in terms of who should have received the blame. Also, I should have noted half the mechanical induced... oops, my bad. Yes, weather induced crashes are of greater concern/frequency.  Smile

I personally believe the pilot gets blamed a lot of the time when they shouldn't. But that's only my  twocents 

I was once on a tristar and asked the stewardess why the engine wasn't turning in cruise... as a 7 year old kid (at the time) she insisted it was turning... I knew it wasn't. Now with what I know about gas turbine engines, I would have been a lot more worried! But the flight continued on (ATL-JAX) as if nothing was wrong.

I've seen the statistics on how rare in flight shutdowns have become. But as we say, FOD happens... (among other resons an engine won't perform as intended).

Lightsaber

Topic: RE: Single Engine Airliners Of The Future?
Username: Kl671
Posted 2006-12-01 03:27:27 and read 4607 times.

Quoting Bond007 (Reply 19):
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

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 course or farmers field if the engine quits.

For a large single engine commercial aircraft, I suspect that high cruise speed combined with a very low stall speed are not the best combinations to make an efficient airliner. There is always the problem of finding that golf course mid Atlantic.

Topic: RE: Single Engine Airliners Of The Future?
Username: Bond007
Posted 2006-12-01 06:36:09 and read 4560 times.

Quoting Kl671 (Reply 37):
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 course or farmers field if the engine quits.

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.

.....but I think we agree that if this ever happens, many regulations would have to change, so we shouldn't be assuming the aircraft would be built with the current FAA regs in mind.

As it stands, and as mentioned in the second post, it's impossible to have a single engine airliner under current regs anyway.


Jimbo

Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-12-01 15:48:17 and read 4502 times.

Quoting Kl671 (Reply 37):
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 course or farmers field if the engine quits.



Quoting Bond007 (Reply 38):
Correct

Do you have a reference for this?
Regulation number?

Topic: RE: Single Engine Airliners Of The Future?
Username: Vzlet
Posted 2006-12-01 16:15:47 and read 4491 times.

Quoting Kl671 (Reply 37):
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 course or farmers field if the engine quits.



Quoting Bond007 (Reply 38):
Correct



Quoting SlamClick (Reply 39):
Do you have a reference for this?
Regulation number?

I believe Kl671 and Bond007 are referencing the Part 23 61-knot requirement, but that only applies to "Normal, Utility, Acrobatic, and Commuter Category Airplanes".

Part 25, for Transport Category Airplanes, states "The reference stall speed, VSR, is a calibrated airspeed defined by the applicant. VSR may not be less than a 1-g stall speed."


(But I assume you already knew that, Slamclick, and were just testing us!)

Topic: RE: Single Engine Airliners Of The Future?
Username: Lemurs
Posted 2006-12-01 19:04:46 and read 4467 times.

You can never have a 100% reliable piece of technology, espcially one that involves high temperatures, high speeds, and moving parts. Therefore, as long as safety is a serious concern of your project, you can never do away with redundancy. Redundancy will be a part of your life for as long as you value your life, regardless of how reliable technology gets. The odds have to go from "very low" to "virtually inconcievable" before the tradeoff starts to make sense again.

If you knew that once every 5 years, a plane would *definitely* crash killing all on board because of a lack of a second engine, would you call that a good risk? How about once every 50 years? Starting to get more appealling, right? Still kinda scary though...but that's probably where reliability would have to go before you could make the case convincingly to the public. Keep in mind we're NOWHERE near that mark now. Engines fail on a regular basis at the moment, often at or after takeoff, where a single engined airplane would almost be guaranteed to become a fireball.

Topic: RE: Single Engine Airliners Of The Future?
Username: Pelican
Posted 2006-12-01 22:05:04 and read 4425 times.

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 would have to work too many hours, but why not on intra-continental flights?

pelican

Topic: RE: Single Engine Airliners Of The Future?
Username: DHHornet
Posted 2006-12-03 21:53:56 and read 4321 times.

Quoting 2H4 (Reply 26):
I'm still holding out for the return of 1000-foot long luxury zeppelins, complete with staterooms, cigar parlors, crushed velvet furniture, and a piano bar.

Ah yes....it will be the sophisticated, gentleman's way to travel....

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 in the future?

Caravans do scheduled flights with a single engine carrying 12 paying passengers at the moment. So we are at a point that some authorities allow this to happen now. Is that immoral? Is the plane a death trap? That’s what some of you are saying!

So in 30+ years? I still think we will see a large airliner powered with one engine in service. Made of metal that floats, runs on water….or a flying carpet with bird pulling it!  wink 

Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-12-03 22:28:23 and read 4312 times.

Quoting DHHornet (Reply 43):
Is that immoral? Is the plane a death trap?

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. So, under our laws it is okay to kill a person every now and then, but you may not kill a hundred at a time, especially when the legislature is in session.

In the US the smaller planes operate under FAR Part 135 which does permit single engine airplanes, does permit scheduled service, but limits the size and seating capacity of the planes. Bigger airplanes, more than 19 seats are operated under FAR Part 121 which specifically prohibits single engine airplanes. (see reply # 1)

So if we are talking about bigger "real airliners" it does come down to rule of law and not technology.

My own opinion - if the new, hypothetical engine is so safe that it CAN NOT have a failure it must be terribly simple and therefore inexpensive. So why not go ahead and hang two of them on my plane anyway?

Topic: RE: Single Engine Airliners Of The Future?
Username: Cloudy
Posted 2006-12-03 23:01:35 and read 4298 times.

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 either the political or the real safety issues - at least for airliners.

What may be closer is the end of the need for 2 pilots. It is technically possible to have a pilot on the ground fly a plane remotely, and there is talk of deploying this capability as a safeguard against 9-11 style attacks. The crew need only push a button for a ground pilot to take over - or perhaps ATC could do it on their own. There is no technical reason modern jets need 2 pilots, except for long trips and as backup. If the plane can be operated remotely at the push of a button, that could serve as the backup capability. Well, having a second set of eyes does help avoid certain accident causing mistakes - but new planes could have cockpits designed to minimize the additional risk.

IMHO this is still a long way off but only for political reasons. It almost certainly will happen eventually, and before anyone seriously considers deploying a single engined jetliner. When we have safe and legal one-pilot airliners (except for very long flights), it will revolutionize service to small cities. Having only one pilot is IMHO the only way VLJ's can live up to their hype. Its worth working for.

Topic: RE: Single Engine Airliners Of The Future?
Username: BoeingOnFinal
Posted 2006-12-03 23:31:35 and read 4285 times.

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 never, but looking from the economical side of things, you need to think about what the passengers want. Would you get on a plane with no pilots? Would you get on a plane with one engine?

From my perspective, I could say yes to the second one, but as far as the "no pilot" goes, it's a definately NO.

Topic: RE: Single Engine Airliners Of The Future?
Username: 747400sp
Posted 2006-12-04 01:13:55 and read 4260 times.

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. The engine would need at least 40000lb of trust for even that aircraft. But I do not even like the ideal of twin engine jet going across the Pacific let lone a single engines jet liner, I still would like to see five engine jet flying over seas today.

Topic: RE: Single Engine Airliners Of The Future?
Username: 2H4
Posted 2006-12-04 01:16:47 and read 4257 times.




Quoting 747400sp (Reply 47):
I still would like to see five engine jet flying over seas today.

Why? It would be no safer.



2H4


Topic: RE: Single Engine Airliners Of The Future?
Username: SlamClick
Posted 2006-12-04 01:56:12 and read 4254 times.

Quoting 747400sp (Reply 47):
I still would like to see five engine jet flying over seas today.

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.

Topic: RE: Single Engine Airliners Of The Future?
Username: David L
Posted 2006-12-04 02:17:23 and read 4238 times.

Quoting SlamClick (Reply 49):
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.

... and look down and see nothing but mattresses.

Topic: RE: Single Engine Airliners Of The Future?
Username: Starlionblue
Posted 2006-12-04 02:29:50 and read 4238 times.

Quoting SlamClick (Reply 44):
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. So, under our laws it is okay to kill a person every now and then, but you may not kill a hundred at a time, especially when the legislature is in session.

Every time I think I'm cynical, Captain Click is there to show me I'm not cynical enough.  Wink

Quoting SlamClick (Reply 44):
My own opinion - if the new, hypothetical engine is so safe that it CAN NOT have a failure it must be terribly simple and therefore inexpensive. So why not go ahead and hang two of them on my plane anyway?

... or logical enough. Big grin

Quoting DHHornet (Reply 43):
Some of you should use your imagination more, and you should never, say never! Do you really know what technology will bring in the future?

Absolutely never say never. There may well be a one engine large airliner in our future. However, I think we're talking far in the future. We have to start talking one in several hundred million chance of failure. As Captain Click points out, any such device would have to be rather simple to get to those failure rates. And thus it would be simple to put two on there.

But hey, who knows what the future holds. If you had told my grandfather about the 380 or Concorde, he would have told you to check in to a padded room. Big grin

Topic: RE: Single Engine Airliners Of The Future?
Username: Bond007
Posted 2006-12-04 03:11:22 and read 4234 times.

Quoting Cloudy (Reply 45):
There is no technical reason modern jets need 2 pilots, except for long trips and as backup.



Quoting Cloudy (Reply 45):
Well, having a second set of eyes does help avoid certain accident causing mistakes - but new planes could have cockpits designed to minimize the additional risk.

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 pilot error (or human error of some sort), and only around 6% attributed to engine failure, then I'd rather have one engine over one pilot anyday.

As I mentioned before....those who bet on risks today...the insurance companies...weigh heavily against the pilot and his training and hours, rather than necessarily number of engines. Rightly so, according to accident statistics.

Quoting Starlionblue (Reply 51):
Absolutely never say never. There may well be a one engine large airliner in our future. However, I think we're talking far in the future.

That's my philosophy. We had no idea 30 years ago what technology has brought us today.

As for regulations....they change every year. In 20 years time, Part 135 and Part 121 will be VERY different from today.

jimbo


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