Free 173 Best Homemade Tools eBook:  
Become a founding member: 500+ tool plans, full site access, and more.

User Tag List

Results 1 to 6 of 6

Thread: Contra-rotating propellers - GIF

  1. #1
    Content Editor
    Supporting Member
    Altair's Avatar
    Join Date
    Aug 2013
    Posts
    4,895
    Thanks
    913
    Thanked 11,881 Times in 3,657 Posts

    Contra-rotating propellers - GIF

    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

    173 Best Homemade Tools eBook
    Last edited by Altair; Dec 27, 2018 at 03:28 PM.

  2. The Following 5 Users Say Thank You to Altair For This Useful Post:

    baja (Dec 29, 2018), KustomsbyKent (Dec 28, 2018), PJs (Dec 28, 2018), ranald (Dec 29, 2018), Seedtick (Dec 28, 2018)

  3. #2
    PJs
    PJs is offline
    Supporting Member PJs's Avatar
    Join Date
    Sep 2014
    Location
    Northern CA
    Posts
    1,841
    Thanks
    8,322
    Thanked 1,097 Times in 712 Posts

    PJs's Tools
    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.
    ‘‘Always do right. This will gratify some people and astonish the rest.’’
    Mark Twain

  4. #3
    Supporting Member IAMSatisfied's Avatar
    Join Date
    Apr 2017
    Location
    The desolate ranch country of Northeastern corner of New Mexico, USA
    Posts
    366
    Thanks
    255
    Thanked 191 Times in 111 Posts
    Now, if these were only shrouded or ducted, then efficiency would be increased dramatically.

  5. #4
    Supporting Member ranald's Avatar
    Join Date
    Jan 2018
    Location
    Black Mountain Queensland
    Posts
    1,305
    Thanks
    952
    Thanked 352 Times in 245 Posts

    ranald's Tools
    Quote Originally Posted by PJs View Post
    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).

  6. #5
    PJs
    PJs is offline
    Supporting Member PJs's Avatar
    Join Date
    Sep 2014
    Location
    Northern CA
    Posts
    1,841
    Thanks
    8,322
    Thanked 1,097 Times in 712 Posts

    PJs's Tools
    Quote Originally Posted by ranald View Post
    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:

    Contra-rotating propellers - GIF-800px-antonov_an-70_at_paris_air_show_2013_4.jpg

    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.
    ‘‘Always do right. This will gratify some people and astonish the rest.’’
    Mark Twain

  7. The Following User Says Thank You to PJs For This Useful Post:

    ranald (Dec 30, 2018)

  8. #6
    Supporting Member ranald's Avatar
    Join Date
    Jan 2018
    Location
    Black Mountain Queensland
    Posts
    1,305
    Thanks
    952
    Thanked 352 Times in 245 Posts

    ranald's Tools
    Quote Originally Posted by PJs View Post
    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:

    Click image for larger version. 

Name:	800px-Antonov_AN-70_at_Paris_Air_Show_2013_4.jpg 
Views:	404 
Size:	61.4 KB 
ID:	27307

    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.



    173 Best Homemade Tools eBook

  9. The Following User Says Thank You to ranald For This Useful Post:

    PJs (Jan 2, 2019)

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •