Leading edge sweep

[Serge_Krauss]

Sooo, getting back to sweep, it seems like we do this for looks and either way works.

I agree that either way works well, but the question should be what works best for what purposes.

I re-read the whole thread and realize that my last post was somewhat redundant in that the point about taper moving the a.c. inboard had already been addressed quite early by Howard and maybe Keith. Anyway, I think this point is valid and makes taper relevant more than just aesthetically. I remember the old Smoothie ads referring to "windy weather" performance, and I have talked to others who feel that their more elliptically shaped wings are more stable (for Howard, 'less prone to upsets' or 'prone to milder upsets') in gusts. To me that seems to be because the elliptical wing has the furthest inboard a.c. of any normally accepted wing. Also I note that the more extremely tapered designs like the "Firecracker" are prominent at the top of the lists in Australia. Note also what elliptical and highly tapered wings have been on top in classic there.

So here are more extreme examples of useful taper. I hope that you'll forgive my using borrowed internet-posted pictures, a couple from Stunthangar members. The first picture shows a straight-tapered wing  with the same a.c. position as an equivalent elliptical wing superimposed on a "Firecracker". The second is the Bond "Bandolero", with extreme taper. The third shows the 2013 Classic winners "down under": Palmer T-Bird,  Rondinelli "Venus", and extreme-tapered Aldrich "Magnum."  Configurations may be coincidental due to other reasons (Bob Palmer is quite popular there), but I think it shows that the accelerated-taper elliptical wing is very much at home in that element.

edit: I've added a final picture of my short-lived high-aspect-ratio model from 2007, which featured a highly tapered wing. It flew better than I expected in mild gusts for an Aspect ratio of over 6:1

I usually double taper mine in order to ensure that section thicknesses remain constant or increase just slightly spanwise for the reason stated above and for consistency.

SK

[Joseph Patterson]

I like waking up feeling ignorant, even a little stupid. Means there's something to try and figure out. Think about. It's the action of trying that feels good.

 
                 Well Dennis I too wake up feeling ignorant, and even a little stupid. Except I won't say that I like it! But like you I try to think about whatever I'm thinking about and to figure things out. Sometimes I succeed.
                  Mike, I like swept leading edges too!
                  Topic is a good one.
                  If this were a pissing contest, Howard and Brett the winners! Serge, start your @#$^%^(*&^%$ UPHILL!!!
     Doug 

[Air Ministry .]

This is credible.  The optimal amount would be that which makes the plane look coolest. 

I Dissagree . it Should look @#$% Hot .

[Serge_Krauss]

 
If this were a pissing contest, Howard and Brett the winners! Serge, start your @#$^%^(*&^%$ UPHILL!!!
     Doug  

Hmmm... 'have to admit, having awakened not feeling particularly brilliant this morning, I have no idea what this means. Was there a pissing contest back in 2014? What does the rest mean?

SK

Edit: Oh, wait! I just re-read what I wrote myself. Ha! Now I know what it means. 'still not fully aware of the quote's intent in new context, but at least I know what I meant by my part. Thanks for reading.

[EddyR]

 One thing I don't believe anyone mentioned is wing thickness at center and tips on the tapered wing and a non tapered wing. Most but not all tapered wings have thinner wings at the tip than straight wings do. I think this seems to help our models with tapered wing fly better then straight wings. When I used the term tapered I am meaning leading edge sweep. Models  like the Juno and a well known Australian model have sweep in both the leading edge and trailing edge and have very thin tips. These models seem to have very good all around performance but especially in the wind.. My conclusion from my experience is leading edge sweep ON FLAPPED MODELS does fly better than straight wing models.
 That is my answer to the original question. 
NOTE  In the answer above I used the term "I" meaning it is my personal feeling not a proven answer.
Ed

[Chris McMillin]

oops



 







  

[Motorman]

  I would like to know why most stunter wings have leading edge sweep and what would be the optimum amount.
                                                                                                   Juan

Just copy ThunderGazer.

MM