Page 1 of 4 1234 LastLast
Results 1 to 15 of 55

Thread: Swept-forward, shoulder-wing configuration

  1. #1
    Registered User cluttonfred's Avatar
    Join Date
    Feb 2010
    Location
    World traveler
    Posts
    3,651
    Likes (Given)
    792
    Likes (Received)
    1124

    Swept-forward, shoulder-wing configuration

    Hi, all. In my own design musings I keep returning to the shoulder-wing configuration with one or two seats ahead of the spar as a great combination in terms of simplicity and visibility, even if it is often necessary to sweep the wing forward a bit to make the CG work.

    A few examples are the homebuilt Andreasson BA-7 (which led to the factory-built Malmö Flygindustri MFI-9 Junior and the Bölkow Bo 208), homebuilt Viking Cygnet and homebuilt Pottier P.130 Bleu Citron (images of all three below).

    What are the pros and cons of this configuration? Why don't we see it more often?

    Cheers,

    Matthew
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	4589598543_bab918fb0a_o.jpg 
Views:	364 
Size:	86.2 KB 
ID:	35883   Click image for larger version. 

Name:	SF2.jpg 
Views:	386 
Size:	42.5 KB 
ID:	35884   Click image for larger version. 

Name:	5621.jpg 
Views:	588 
Size:	54.7 KB 
ID:	35885  

    *******
    Matthew Long, Editor
    cluttonfred.info
    A site for builders, owners and fans of Eric Clutton's FRED

    « Voici ce que j'ai fait...vous pouvez en faire autant! »
    "This is what I have done...you can do the same!"
    --Henri Mignet (1893-1965)

  2. #2
    Registered User BBerson's Avatar
    Join Date
    Dec 2007
    Location
    Port Townsend WA
    Posts
    7,176
    Likes (Given)
    1231
    Likes (Received)
    1069

    Re: Swept-forward, shoulder-wing configuration

    Sure, it will work if the sweep isn't too extreme such as 3° used for the Bolkow.
    Too much sweep might cause torsion instability (tips could twist up). Not good. I don't know what is too much.
    John Roncz chose forward sweep for his design.
    Forward sweep helps delay tip stall. That's good.

  3. #3
    Registered User FritzW's Avatar
    Join Date
    Jan 2011
    Location
    Las Cruces, NM
    Posts
    1,816
    Likes (Given)
    1396
    Likes (Received)
    1712

    Re: Swept-forward, shoulder-wing configuration

    Great minds think alike Matthew

    If you remember the renderings I've posted of the 'Router Lark' it has a sort of Westland Lysander shaped wing to solve the CG issue.

    A friend of mine built an all wood single seat Cygnet (never finished), it was beautiful.

    P.S. Don't forget the Nord 8xx

    Iēsous Christos, Theou Yios, Sōtēr

  4. #4
    Registered User cheapracer's Avatar
    Join Date
    Sep 2013
    Location
    Australian
    Posts
    3,756
    Likes (Given)
    2351
    Likes (Received)
    2097

    Re: Swept-forward, shoulder-wing configuration

    Quote Originally Posted by cluttonfred View Post
    What are the pros and cons of this configuration? Why don't we see it more often?
    Having a wing punched into the side of your head in an accident?
    Quote Originally Posted by BoKu View Post
    The vast majority of engineering failures are the results of failure of imagination rather than failure of calculation.

  5. #5
    Registered User FritzW's Avatar
    Join Date
    Jan 2011
    Location
    Las Cruces, NM
    Posts
    1,816
    Likes (Given)
    1396
    Likes (Received)
    1712

    Re: Swept-forward, shoulder-wing configuration

    ...I wish there was a "Dislike" button
    Iēsous Christos, Theou Yios, Sōtēr

  6. #6
    Registered User cluttonfred's Avatar
    Join Date
    Feb 2010
    Location
    World traveler
    Posts
    3,651
    Likes (Given)
    792
    Likes (Received)
    1124

    Re: Swept-forward, shoulder-wing configuration

    Thanks, all, for the comments and of course with my twin tail fixation I should have mentioned the Nord. Cheapracer, I am not sure if you are being facetious or not but I don't really see any significant crash danger there, maybe you could elaborate? If you're thinking that the wings would fold forward in a sudden stop, I supposed that the inner spars could be made deliberately over strong with a discontinuity to encourage the wing to breakaway further outboard, though I suspect that in a crash that severe you'd have other issues to worry about as well.
    *******
    Matthew Long, Editor
    cluttonfred.info
    A site for builders, owners and fans of Eric Clutton's FRED

    « Voici ce que j'ai fait...vous pouvez en faire autant! »
    "This is what I have done...you can do the same!"
    --Henri Mignet (1893-1965)

  7. #7
    Registered User FritzW's Avatar
    Join Date
    Jan 2011
    Location
    Las Cruces, NM
    Posts
    1,816
    Likes (Given)
    1396
    Likes (Received)
    1712

    Re: Swept-forward, shoulder-wing configuration

    Iēsous Christos, Theou Yios, Sōtēr

  8. #8
    Registered User cheapracer's Avatar
    Join Date
    Sep 2013
    Location
    Australian
    Posts
    3,756
    Likes (Given)
    2351
    Likes (Received)
    2097

    Re: Swept-forward, shoulder-wing configuration

    Quote Originally Posted by cluttonfred View Post
    I am not sure if you are being facetious or not but I don't really see any significant crash danger there, maybe you could elaborate?
    Sure, large chunks of metal close to one's head, first thing I think of every time I see a shoulder wing and why I wouldn't fly in one.

    You asked a question specifically requesting pros and cons, I gave you my honest answer and there is plenty of circumstance that the wing, or parts thereof, would go straight through that Pilots head.

    Alternately, the Pilot's head is also simply to close to the structure and even in a minor accident could be a serious outcome - and FWIW, no way does it meet standard FIA car racing 'head to structure' clearance rules. There are plenty of inboard car race crash videos to see how far a head travels in accidents, scary stuff.

    Click image for larger version. 

Name:	headbutt.jpg 
Views:	192 
Size:	16.4 KB 
ID:	35888.


    Quote Originally Posted by FritzW View Post
    ...I wish there was a "Dislike" button
    I'll keep that card for use later.

    You say you are an "ex-Cop", if true you have seen what happens to peoples heads in car and machinery accidents, you have also seen how small an impact to the head can kill, but most of all you have also seen weird stuff that you wouldn't think otherwise possible, I most certainly have and choose to keep everything as far away from my skull as possible.
    Quote Originally Posted by BoKu View Post
    The vast majority of engineering failures are the results of failure of imagination rather than failure of calculation.

  9. #9
    Registered User cluttonfred's Avatar
    Join Date
    Feb 2010
    Location
    World traveler
    Posts
    3,651
    Likes (Given)
    792
    Likes (Received)
    1124

    Re: Swept-forward, shoulder-wing configuration

    Guys, let's not get cranky, there is no need for it in a friendly forum.

    Cheapracer, I do see your point and it's certainly a consideration to keep in mind and perhaps an argument in addition to visibility for the cutout where the wing joins the fuselage in the BA-7/MFI-9/Bo 208. I would be less worried about structure behind the pilot's head, often there for rollover protection and seat harness support in any case, than structure ahead or to the sides of the head. I think you can see from this MFI-9 close-up that there is no structure in the 145 degree or so arc from the passengers' heads. There is also no need for there to be major rigid structures forward of the spar at the junction of the canopy and wing root, there could be light fairings or even hollow extensions of the canopy itself, a bit like the old Praga Baby.

    Click image for larger version. 

Name:	mfi-9 cockpit detail.jpg 
Views:	742 
Size:	41.6 KB 
ID:	35889 Click image for larger version. 

Name:	praga baby cabin top open.jpg 
Views:	311 
Size:	42.5 KB 
ID:	35890

    In my own design evolution I am focusing on minimum structure and maxiumum building simplicity. Nonetheless, I was thinking of using a two-piece cantilever wing joined by a bending beam so strut bracing angles are not a factor. The wing postion I have in mind would be more "elbow wing" than "shoulder wing" so no head injury issues but at the cost of reduced visibility downward and rearwards. Take an Andreasson BA-7, add a dash of Evans Volksplane VP-2 and maybe a simple rectalinear H-tail and perhaps you can imagine where this is going. ;-)
    *******
    Matthew Long, Editor
    cluttonfred.info
    A site for builders, owners and fans of Eric Clutton's FRED

    « Voici ce que j'ai fait...vous pouvez en faire autant! »
    "This is what I have done...you can do the same!"
    --Henri Mignet (1893-1965)

  10. Likes Doggzilla liked this post
  11. #10
    Registered User cheapracer's Avatar
    Join Date
    Sep 2013
    Location
    Australian
    Posts
    3,756
    Likes (Given)
    2351
    Likes (Received)
    2097

    Re: Swept-forward, shoulder-wing configuration

    Quote Originally Posted by cluttonfred View Post
    Guys, let's not get cranky, there is no need for it in a friendly forum.
    Quote Originally Posted by BoKu View Post
    The vast majority of engineering failures are the results of failure of imagination rather than failure of calculation.

  12. #11
    Registered User cluttonfred's Avatar
    Join Date
    Feb 2010
    Location
    World traveler
    Posts
    3,651
    Likes (Given)
    792
    Likes (Received)
    1124

    Re: Swept-forward, shoulder-wing configuration

    Food for thought...

    Take a look at the original Andreasson BA-7 (1958) all-moving vertical and horizontal tail, later changed to a fixed, swept vertical fin and rudder though the all-moving horizontal tail was retained. I don't think the similarity of the Volksplane VP-1 (1968) and VP-2 (1971) tail arrangement is simple coincidence as both Andreasson and Evans worked at Convair in San Diego, though I don't know if they actually worked together.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	4589598543_bab918fb0a_o.jpg 
Views:	122 
Size:	86.2 KB 
ID:	35891   Click image for larger version. 

Name:	01.jpg 
Views:	145 
Size:	76.8 KB 
ID:	35892  
    *******
    Matthew Long, Editor
    cluttonfred.info
    A site for builders, owners and fans of Eric Clutton's FRED

    « Voici ce que j'ai fait...vous pouvez en faire autant! »
    "This is what I have done...you can do the same!"
    --Henri Mignet (1893-1965)

  13. Likes billyvray liked this post
  14. #12
    Registered User billyvray's Avatar
    Join Date
    Aug 2005
    Location
    Newnan, GA
    Posts
    417
    Likes (Given)
    205
    Likes (Received)
    67

    Re: Swept-forward, shoulder-wing configuration

    Might as well mix it up some more: pinch the root ribs in like a Wittman Tailwind, add an all-moving V-tail like a Davis (or H-tail like an Ercoupe). simple structure and good visibility.

    Bill

  15. #13
    Registered User Doggzilla's Avatar
    Join Date
    Jun 2013
    Location
    Everywhere USA
    Posts
    1,122
    Likes (Given)
    580
    Likes (Received)
    254

    Re: Swept-forward, shoulder-wing configuration

    Quote Originally Posted by cheapracer View Post
    Having a wing punched into the side of your head in an accident?
    As if your head is just gone sit there and get cracked open. If anything, your head will be moving forward in a crash while the spar stays in place. Striking the side of the canopy is the main killer in aviation. A shoulder spar is no problem, and I dare anybody to show an example of someone being killed in one.

    In fact, I'm sure the other spar designs kill just from lack of vision. Lots of high wing low wing visibility accidents, no shoulder wing head crushing accidents. That's a good enough record for me. Isn't too shabby, in the overall view of things.
    Your work is going to fill a large part of your life, and the only way to be truly satisfied is to do what you believe is great work. And the only way to do great work is to love what you do. If you haven't found it yet, keep looking. Don't settle. As with all matters of the heart, you'll know when you find it.
    And no, we don't know where it will lead. We just know there's something much bigger than any of us here.



  16. #14
    Registered User cluttonfred's Avatar
    Join Date
    Feb 2010
    Location
    World traveler
    Posts
    3,651
    Likes (Given)
    792
    Likes (Received)
    1124

    Re: Swept-forward, shoulder-wing configuration

    Thanks, guys. Like in nerobro's bargain racer, it's not lost on me that this configuration basically allows the wing to simply sit on top of the fuselage top longerons. Also, if you were to use a one-piece, forward-hinged canopy like a Minicab and integrate the "headrest" fairing in the canopy or wing, it's easy to imagine a quick-folding wing along the top of the rear fuselage, with our without an H-tail.

    I do think cheapracer has a point about keeping the hard and pointy bits away from people's heads so that's something to keep in mind. As Doggzilla said, every wing location has pros and cons including safety issues -- high wing visibility in a turn, low-wing crashworthiness with the unyielding spar under the seats, etc.

    PS--In an interesting twist, the homebuilt BA-7 became the factory-built MFI-9 and Bo-208, and later spawned the SAAB MFI-15 and -17 and the Pakistani Mushshak. But at some point, MFI also offered the plane as...a kit for homebuilders! Here is my latest discovery, the MFI-9HB (homebuilt) info pack from http://www.boelkow-junior.de/d/MFI-9HB.pdf. Enjoy!
    Attached Files Attached Files
    Last edited by cluttonfred; November 3rd, 2014 at 12:44 PM. Reason: Added MFI-9HB info packet
    *******
    Matthew Long, Editor
    cluttonfred.info
    A site for builders, owners and fans of Eric Clutton's FRED

    « Voici ce que j'ai fait...vous pouvez en faire autant! »
    "This is what I have done...you can do the same!"
    --Henri Mignet (1893-1965)

  17. Likes steveair2 liked this post
  18. #15
    Registered User cheapracer's Avatar
    Join Date
    Sep 2013
    Location
    Australian
    Posts
    3,756
    Likes (Given)
    2351
    Likes (Received)
    2097

    Re: Swept-forward, shoulder-wing configuration

    Quote Originally Posted by Doggzilla View Post
    As if your head is just gone sit there and get cracked open. If anything, your head will be moving forward in a crash while the spar stays in place.
    Entirely based on the assumption that it is a forward impact, if life was only so predictable.

    Quote Originally Posted by Doggzilla View Post
    Striking the side of the canopy is the main killer in aviation.
    Aha, now we are getting somewhere, would you rather strike a nice flat flexible bit of plastic or that wing end pictured above.

    Sorry guys, I've just pulled one too many people out of car wrecks I guess, please consider your head and what it will hit within a 2ft/600mm radius and know a lot of people have died in car accidents from their heads hitting the B Pillar.

    We are pretty darn fragile things.
    Quote Originally Posted by BoKu View Post
    The vast majority of engineering failures are the results of failure of imagination rather than failure of calculation.

Similar Threads

  1. CG of swept tapered wing?
    By rtfm in forum Aircraft Design / Aerodynamics / New Technology
    Replies: 16
    Last Post: January 9th, 2014, 07:57 AM
  2. Forward Swept Wings - a question
    By rtfm in forum Aircraft Design / Aerodynamics / New Technology
    Replies: 25
    Last Post: October 29th, 2013, 07:44 PM
  3. Swept Wing Lift
    By Docskyhawk in forum Aircraft Design / Aerodynamics / New Technology
    Replies: 3
    Last Post: March 29th, 2013, 12:36 PM
  4. Forward swept wings
    By Leighton in forum Hangar Flying
    Replies: 29
    Last Post: December 28th, 2011, 01:47 PM
  5. Swept wing & Wing Taper
    By rtfm in forum Aircraft Design / Aerodynamics / New Technology
    Replies: 6
    Last Post: April 11th, 2011, 08:47 PM

Posting Permissions

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