Contra-rotating propellers - GIF

[Altair]

Contra-rotating propellers of an Antonov An-70. The An-70 is powered by four Progress D-27 three-shaft propfan engines, each capable of producing 10,350kW of output power.




Previously:

Stratolaunch the world's largest aircraft - video
Bell Boeing V-22 Osprey unfolding - GIF and photos
Painting a 777 airplane - GIF

[PJs]

Technically I believe it is a Propfan and not a Scimitar prop although the shape is true. A mere 55,518 hp but the AN70's max take off weight is 319,670 lb...wonder what kind of thrust those props produce to kick that baby off the ground ground in 2000 feet with 25 tons of cargo. It's an impressive beast of burden and the prop-fans are pretty impressive looking as well as giving lift to the wings as a STOL. Note the distance between the two props and the small diameters. Small diameter keeps the tip speed down and the distance between gives better fuel consumption.

[IAMSatisfied]

Now, if these were only shrouded or ducted, then efficiency would be increased dramatically.

[ranald]

Technically I believe it is a Propfan and not a Scimitar prop although the shape is true. A mere 55,518 hp but the AN70's max take off weight is 319,670 lb...wonder what kind of thrust those props produce to kick that baby off the ground ground in 2000 feet with 25 tons of cargo. It's an impressive beast of burden and the prop-fans are pretty impressive looking as well as giving lift to the wings as a STOL. Note the distance between the two props and the small diameters. Small diameter keeps the tip speed down and the distance between gives better fuel consumption.

They don't seem to have a lot of pitch. How does this affect the torque? (obviously, I have NO knowledge on the subject & may seem 2b a very silly question but that is some big mother with or without a load).

Aside: Looks a little like my portable saw which has a totally different use to my dado sets (blades of which ((of course)) turn the same way).

[PJs]

They don't seem to have a lot of pitch. How does this affect the torque? (obviously, I have NO knowledge on the subject & may seem 2b a very silly question but that is some big mother with or without a load).

Aside: Looks a little like my portable saw which has a totally different use to my dado sets (blades of which ((of course)) turn the same way).

It is a big MO. I saw a special while back about a service that uses them and they transported a wind turbine blades from Malaysia to Colorado jobsite a while back that had an impossible deadline. The front and back end open up to allow drive thru for loading and unloading.

Actually they do have quite a bit of pitch. I thought they might be variable pitch but can't find evidence of that but a close inspection of the pic I believe they are. Here is a close up of the props from the side from wiki:



Also some good history of the prop-fan and it's efficiencies on wiki and some clues as to why no ducting for high lift wing profiles.

[ranald]

It is a big MO. I saw a special while back about a service that uses them and they transported a wind turbine blades from Malaysia to Colorado jobsite a while back that had an impossible deadline. The front and back end open up to allow drive thru for loading and unloading.

Actually they do have quite a bit of pitch. I thought they might be variable pitch but can't find evidence of that but a close inspection of the pic I believe they are. Here is a close up of the props from the side from wiki:



Also some good history of the prop-fan and it's efficiencies on wiki and some clues as to why no ducting for high lift wing profiles.

Thanks: interesting that the rear ones seem to have more pitch than the front ones but that may be just me. A close look & you may well be right again about variable pitch.