You mean like this??

Old Widgets never die, they just smell that way!

So that's what an un-ducted fan looks like!

Or also... HBDAN

I would think that airport noise would be the main problem for props in the 100+ seat range. Noise pollution was a big factor in the demise of the unducted fan. But there are probably technological fixes for this by now.

Quoting Cloudy (Reply 4): The article said that engine noise INSIDE the a/c was also a problem.

Old Widgets never die, they just smell that way!

I doubt that this would happen. Noise would be one factor that would slow this down. As well, would they be as effeceint as a fan engine? I know fan engines probably use more fuel, but would they not use it more effectivly? Imagine a 747 or 380 with props...

DW over and out!

What does anyone think of using the Russian-style counter-rotating dual props? View Large View Medium Photo © Lystseva Marina - Russian AviaPhoto Team View Large View Medium Photo © George Canciani

Ich haben zwei Platzspielen und ein Microphone

Props are noisy - more than jets most of the time - no matter what their configuration. Props are slower than jets over long distances. Most of the world perceives props as less reliable than jets - which I'm not sure is valid. Will props replace large aircraft - no. I think the efficiency of jets for heavy loads at good speeds will beat props. However, I would not be surprised to see the 50 to 70 seat regional jet market disappear, replaced by turbo-props over the next ten years. Especially for flights under 500nm.

Quoting RFields5421 (Reply 8): Props are noisy Props are cheaper and more fuel efficient. Which do you think is going to win out? Quoting RFields5421 (Reply 8): Props are slower The news this week was that the jets were going to fly slower to save fuel. Quoting RFields5421 (Reply 8): Most of the world perceives props as less reliable than jets Soon most of the world won't be able to afford a plane ticket. All I am saying is that something has got to give. If fuel goes any higher props will have to be back on the table. Quoting RFields5421 (Reply 8): Will props replace large aircraft - no. Probably not however the larger jet routes may get fewer frequencies on selected routes. Certainly a good topic here and worth exploring and discussing further.

Quoting RFields5421 (Reply 8): However, I would not be surprised to see the 50 to 70 seat regional jet market disappear, replaced by turbo-props over the next ten years. Especially for flights under 500nm. I totally agree. These 50 to 70 seater RJ will disappear.

I recall reading that the Delta Board decided on the MD-80s instead of 737s when a MD salesperson showed them a MD-80 model, snapped off the engines, and snapped on unducted fan engines, thereby demonstrating that should fuel prices spike Delta could readily replace the engines and thereby recognize significant fuel savings. I think I read that in the WSJ, but it was so long ago I may be wrong. Can anyone confirm the story?

There was another thread on this subject a few months ago in the Tech/Ops forum. http://www.airliners.net/aviation-forums/tech_ops/read.main/206513/

Quoting HBDAN (Reply 3): Might have to re-brand to EasyUDF

You know either this or a geared turbofan could save the MD-80... funny to think that everybody laughed at American and SAS for keeping them... but it could be done.

2 years ago I was talking to a friend at GE who said that they were thinking of bringing the UDF back. It would be great way to suddenly save the MD-80's and who knows, maybe even the NW DC-9's would go another 20 years with UDF's strapped to the back. They couldn't be any louder than they already are.   727forever

Quoting Cloudy (Reply 4): Noise pollution was a big factor in the demise of the unducted fan. But there are probably technological fixes for this by now. Its called a geared turbo fan!    Quoting RFields5421 (Reply 8): Props are noisy - more than jets most of the time - no matter what their configuration. Exactly. Why? Shedding off of the blade tips. A ducted fan (e.g., a GTF) will always be quieter. Also, a ducted fan has much better efficiency above M=0.6. Since no one is talking about going *that* slow, the next course should be the GTF.   Ok, where does the propeller have an efficiency advantage? Climb. By not carrying the weight of the nacelle, the airframe is always going to have better climb efficiency. Quoting HBDAN (Reply 3): Or also... Your photo is an excellent start on a discussion on Prop fans. Notice how the propellers are behind the cabin? That is to protect the passengers in a blade out situation. A prop fan is extreamly dangerous in bird strike conditions. To meet today's regulations, I see no way other than a variety of the pusher in the photo. But think about weight. That thrust from the engines must have structure to move it to the main source of drag: the wings. Hence why tail mounted engines always put a weight penalty upon the airframe as there must be more structure between the tail engine(s) and the wing. I think we'll continue to see props on sub-100 seat aircraft. We'll probably see a nice new 100 seater with propellers. Perhaps even a prop-fan. But the GTF brings in competition with the prop.    Basically, a GTF will always win in efficiency for routes over 1000nm. Somewhere below that the prop fan will have better economics. Fuel isn't getting cheaper... but the gas turbine isn't a static target either.   Lightsaber

If at first it doesn't fly, put on a bigger engine!

Quoting Crewchief (Reply 11): I recall reading that the Delta Board decided on the MD-80s instead of 737s when a MD salesperson showed them a MD-80 model, snapped off the engines, and snapped on unducted fan engines, thereby demonstrating that should fuel prices spike Delta could readily replace the engines and thereby recognize significant fuel savings. I think I read that in the WSJ, but it was so long ago I may be wrong. Who knows what may have been said during negotiations, but it was never a technically plausable option to swap the JT8D for a UDF without a number of modifications. The vibration environment is more potent with a UDF which directly affects the fatigue life of the engine pylons and rear fuselage. More than likely, it was just MD showing off an evolutionary "road map" for the MD-80 series. The MD-91X, -92X, and -94X were all various proposals that utilized a UDF. Quoting KarlB737 (Reply 9): Props are cheaper and more fuel efficient. Which do you think is going to win out? The news this week was that the jets were going to fly slower to save fuel. Do not make the mistake of forgetting labor. It costs a boat load to keep 2 pilots and the necessary FAs on payroll longer than necessary. The same stories of airlines cruising slower also mention how the fuel savings must be balanced with the increase in labor cost. Saying that props are "cheaper" is a forgone conclusion. In many applications, they would be more costly.

Comventional props may be up to 80 seats. Above that, we will see ducted props, and the GTF is an example of how a prop looks like in 2010.

Heck Frontier had those cvr 580,s Texas intl had soeme cvr, southern had the martin 404 and i had no problem fling them they seemed to have more room than the rj,s The ys-11 was a good plane with an rr engine

i can see for 80 miles

Quoting RFields5421 (Reply 8): Most of the world perceives props as less reliable than jets - which I'm not sure is valid. Perception is reality to most people. Think about it. Old movies, old pictures, old memories, old wars...all of them depict aviation with piston engined or turbo-prop powered aircraft (this is also a difference that is beyond most people...props are props to almost everyone, even though piston engines and turboprops are two totally different things). If the perception of being "old" technology wasn't enough, you have two more problems. First of all, all of the prop planes that most people would commonly fly on or see are private planes (Cessnas etc...) and regional turboprops. These are typically small, noisy, and creaky, not because they are props (well noise...but), but because they are cramped and typically offer less separation from the environment. I've also heard more than one person say they consider props "dirty" (probably because more of the machinery is exposed). Additionally, there are a lot of older propeller driven airliners still in service, and they do everything but carry passengers, which makes them seem "inferior" to the flying public. Overcoming these perceptions is an almost insurmountable barrier for props to be accepted again for mainline travel. -IR

Saab tried - on the Saab 2000 - to overcome this with blades that look futuristic.

Quoting IRelayer (Reply 20): Overcoming these perceptions is an almost insurmountable barrier for props to be accepted again for mainline travel. I disagree. Selling the benefit of your product is what marketing departments are for. There's never been any real impetus to market "against the grain" before now; the 37- and 50-seat RJ's weren't the money pit that they have become at $100+ oil. So nobody (at least in the US) has bothered to seriously combat the old prop image. I think if someone really wanted to fly a mainline or near-mainline sized turboprop, it wouldn't be all that hard to sell; it would just take a bit of work. (That's assuming a half-decent product, of course.)

Fly, you fools! Fly!

Quoting Acidradio (Reply 7): What does anyone think of using the Russian-style counter-r