If an aircraft winglets are supposed to reduce lift induced drag by reducing/alleviating the amount of vortices and spillage of air over the wing, why don't propellers what mini winglets too?

not 100%, but im guessing that old friend centripetal force has a part to play!

Do you mean winglets on prop planes?

Well if yes then this one does

http://www.airliners.net/open.file?id=349396

Want winglets on your props? Try a gear-up landing.

In fact, some types of props have winglets (or is it proplets ? ). Although the main advantage is noise reduction. They are called Q-tip props.
Here is a picture : http://www.airliners.net/open.file/716566/L/

touchez, you learn something new every day!

Good one I needed a good laugh!

And, if you want to carry the "proplet" idea a bit further you might consider the Unducted Fan.
http://www.airliners.net/open.file/405754/M/

What the heck is that?

A project that never really came to fruition.

The McDonnell Douglas MD-94X was a planned propfan-powered airliner, intended to begin production in 1994. The aircraft was to seat between 160 and 180 passengers in an unknown seating configuration. An all-new design, it was begun in the late 1980s to compete with the similar Boeing 7J7. Configuration was similar to the MD-80, but advanced technologies such as canard noseplanes, laminar and turbulent boundary layer control, side-stick flight control (via fiber optics), and aluminum-lithium alloy construction were under consideration.

Airline interest in the brand-new propfan technology was weak despite claims of up to a 60% reduction in fuel use, and both aircraft were cancelled.

http://en.wikipedia.org/wiki/McDonnell_Douglas_MD-94X

A propfan is a modified turbofan engine, with the fan placed outside of the engine nacelle on the same axis as the compressor blades. Propfans are also known as ultra-high by-pass (UHB) engines. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop.

More- http://www.aerospaceweb.org/question/propu...ion/q0067.shtml

Hey SF3aviatrix:

Do you remember the relatively short-lived television series on Fox, called "John Doe?" The guy had no memory of anything, including his own identity -- but, the interesting part was that he knew the answer to any and all questions, regardless of the subject or source. I was just wondering if you might be related to him???????? :lol:

I wonder what it will take for airlines to try new technology. The propfan seems like a really good idea, although I suspect it is pretty noisy...gotta get a duct on it!!. I suppose fuel was pretty cheap in 1994.....

What did the airlines consider to be the downside of this concept.

Probably cost. I think the unducted fan concept might be great for today's world of aviation!

It was noisier than hell, for one thing. If I remember correctly, it was test flown out of Long Beach, CA. Ultimately, it was the noise and the perceived lack of demand that ended the idea. Again, if memory serves.

I don’t know the cost of an unducted fan engine in comparison with a modern turbo-jet/high by-pass engine but I do know that when adjusted for inflation, gasoline prices today are only 37% of what they were in 1955, 70% of what they were in 1972, and 45% of what they were in 1981.

And, yes, the UDF was somewhat "noisy;" but sometimes it just comes down to what do you want to put up with -- noise or empty pockets?

Another thread about the UHB/UDF with a link to an official NASA study about the noise concerns.

http://forum.flightlevel350.com/viewtopic....3507&highlight=

It's not that simple. Most airports are now surrounded by residential land, and people do not want noisy planes. Apparently the TU-95, which is the fastest turboprop prodn plane ever, is SO noisey, even the US pilots that intercepted it over Alaska experienced discomfort from the noise of the props.

Well, I didn't say it was a simple decision nor am I advocating an over-haul of the commercial fleet to UDF operations. I was merely pointing out that when discussing "prop-let" engines, the UDF might be considered -- and that the UDF engine was developed during a time when fuel prices were of significant importance to some.

Besides, folks who build airports today don't do so in the middle of populated areas. Airports are usually built in outlying areas, away from people and problems. For example, the journey from downtown Denver to the airport is quite a trek. It is the people who then move closer to the airports. Why? Land is usually cheaper (because of the noise). Then those same people start to complain about the factors that allowed the prices to be cheaper in the first place. How long do you think it will take for the land around the new Denver airport to be developed and have the new residents start complaining about the "noise?"

Well I agree, that people tend to encroach on airports. But urban growth is well known phenomena. Planes have become more efficient and quiet over the years. I think such planes can be made quiet. Perhaps they will develop active noise cancellation devices that are switched on during landing and takeoff. (they will probably use quite a bit of energy. )

I can second that planes are getting quiter- look at the A380. Whoever has had a chance to see it, all agrees that it is extremely quite. I was looking at the promo website for the 747-8 the other day and boeings claiming that the 747-8 will be 25% quiter than the A380....

The only problem with noise is that people complain too much. First they complain that airlines use too much oil, then they complain about noise. There's gotta be a tradeoff here!

On one of the A380 documentries, they discussed the issue of noise, and it turns out, that during landing, more noise is generated by the airframe then the engines!!! So the solution to that was to lower the landing speed. On takeoff, this is less of a problem as the plane can do a noise abatement takeoff with a very steep climbout. I found this fact to be quite a revelation

I have got another point of view on the noise issue.

The more effort we make to reduce the noise, the more people will complain as they get used to the lower amount of noise and move closer and closer to the airport.
SO...
Lets make A LOT of NOISE! Eventually, they will give up and go away!
What do you think about that?

Yeah the Embraer ERJs are incredibly quiet too.. But so is my cessna, and a passing train.. If you don't like airport noise build yourself a time machine and go back to the stone age..

If everyone goes away...you don't need and airport so it will close..... :lol: