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MD 81 Unducted Fan test aircraft.

Started by SkyBaby, April 16, 2011, 08:25:31 PM

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SkyBaby

Equipment:  Canon EOS 50D; 28-135mm IS 3.5-5.6  Saving up for the Canon 100-400L. 

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NikonGuy

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SkyBaby

Equipment:  Canon EOS 50D; 28-135mm IS 3.5-5.6  Saving up for the Canon 100-400L. 

Wildlife and aviation photographer.

My Facebook photography page. If you like what you see, give me page a thumbs up! I promise not to flood your news feeds. :D
https://www.facebook.com/PhotographybyKiraAndreola

My flickr:
http://www.flickr.com/photos/skys_flickr/

WARBIRD KEITH


SkyBaby

Quote from: WARBIRD KEITH on April 17, 2011, 09:57:07 AM
It sounded like a Piaggio Avanti but a little louder :)


I noticed that.  Not quite a turbo prop.  Not mellow enough. lol  Got a real nice sound I think. 
Equipment:  Canon EOS 50D; 28-135mm IS 3.5-5.6  Saving up for the Canon 100-400L. 

Wildlife and aviation photographer.

My Facebook photography page. If you like what you see, give me page a thumbs up! I promise not to flood your news feeds. :D
https://www.facebook.com/PhotographybyKiraAndreola

My flickr:
http://www.flickr.com/photos/skys_flickr/

Realbigtaco

You know that sound is one of the main reason why the Unducted Fan (UDF) has not caught on in commercial aviation.  When McDonnell Douglas was doing those tests they claimed that the UDF would reduce fuel burn by up to 60% of traditional bypass turbofans.  The timing of the program also occurred at a time when oil prices where fairly low and therefore the fuel burn reduction was not as appealing as it is today.

With that said I know either Rolls Royce or GE is looking into UDF's a lot more today.  However the two big areas they need to concentrate on are noise and fan blade out conditions.  In a traditional turbofan if you lose a blade you aim to have your fan cowl contain your blades.  In a UDF you loose a blade and it will possibly destroy the plane.

NikonGuy

Quote from: Realbigtaco on April 18, 2011, 10:50:54 AM
In a traditional turbofan if you lose a blade you aim to have your fan cowl contain your blades.  In a UDF you loose a blade and it will possibly destroy the plane.

Wow that's pretty scary, how about regular turbo props? Is it not the same?
Fernando Sedeno
Camera: Nikon D90 DSLR
Nikkor DX 18-55mm ED AF
Nikkor 70-300mm ED-IF AF-S VR
Member of... AOPA,PHPA, and ISAP.
www.flickr.com/photos/fernandosedeno
www.helispot.com/who/102247-Fernando+Sedeno/
www.jetphotos.net/showphotos.php?userid=32801
www.flightaware.com/user/Nando08

nmcbride

Quote from: N@Nd0 on April 18, 2011, 11:09:09 AM
Wow that's pretty scary, how about regular turbo props? Is it not the same?

Apparently not.   Sounds cool, but what would the noise pollution people have to say?

"An unducted fan or propfan is a modified turbofan engine, with the fan placed outside the engine nacelle on the same axis as the compressor blades. Propfans are also known as ultra-high bypass (UHB) engines and, most recently, open rotor jet engines. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop."

Realbigtaco

In regards to the noise I'm sure people would hate it.  I work for the biggest engine nacelle company in the world and you would be surprised at how much money is invested into making those engines quieter.  So the unique situation with the propfan is that it is a pretty substantial step back in the noise abatement rules that the FAA set out.  So much so that I think at the current levels of dB's that are put out by propfans, if airlines used them today they could be subject extreme restrictions in use due to the FAA Stage IV noise requirements.  In fact I'm not even sure you can certify a plane with the FAA unless it meets those Stage IV guidelines.

This is one of the big hurdles that this engine has to make.

But then it is a give and take.  This engine has better fuel efficiency and hence also has less pollution (CO2 and NOX). 

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