Joined Wings Aircraft
08-06-2006 | 09:09 AM
#1
Thread Starter
Junior Member
Joined: Aug 2006
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
From: adelaide, AUSTRALIA
Joined Wings Aircraft
Does anyone has any experience in flying or building a joined wing R/C plane before? What characteristics does it carries? I have attempt to look for information on this kinds of wings but all I got was data on high speed plane which does not apply for R/C models
08-06-2006 | 09:52 AM
#2
RE: Joined Wings Aircraft
go ahead and make one -there are lots of examples --a biplane is actually a joined wing
some have two V shaped panels
as long as you figure out the aprox cg (cut a paper planform of the finished setup and balance by picking op with a straight pin)
make it very light - this resolves lots of problems for you
the easiest ,best approach is to obtain some 3 or 6 mm Depron and simply make a simple one from the sheets and power with a small electric setup - easy to fix and modify - then if the mood really strikes you-- do it all larger with a built up model .
some have two V shaped panels
as long as you figure out the aprox cg (cut a paper planform of the finished setup and balance by picking op with a straight pin)
make it very light - this resolves lots of problems for you
the easiest ,best approach is to obtain some 3 or 6 mm Depron and simply make a simple one from the sheets and power with a small electric setup - easy to fix and modify - then if the mood really strikes you-- do it all larger with a built up model .
08-07-2006 | 08:07 AM
#4
Senior Member
Joined: Dec 2002
Posts: 569
Likes: 0
Received 0 Likes
on
0 Posts
From: Edmond,
OK
RE: Joined Wings Aircraft
I can only partially answer your questions, since I have never flown any joined-wing craft other than biplanes, but the following is based on my study of general aerodynamics:
The wings are often staggered to mitigate the significant interference drag between panels joined at less than a 90 degree angle. Unless the panels are staggered (by opposing sweep), the interference drag can far exceed any gains made by elimination of one pair of tip vortices. There will then be losses near the joint caused by the leading wing influencing the trailing wing's local AOA, in turn creating drag and low-speed handling problems. The trailing wing would have to have an unusual twist distribution to account for this without massive increase in induced drag (due to highly non-elliptical CL distribution along the span), and then it would only be "correct" in one flight condition, unless the geometry was variable in flight.
It is complex to design a truly efficient joined-wing airplane (ultimately it would require CFD and wind-tunnel testing). This is why there are few full scale examples of joined-wing craft, other than biplanes.
Dick't right again: A biplane with interplane struts is generally the best form of joined-wing craft, since the panels are joined at 90 degree angles, minimizing interference drag.
Aside from looking cool (in a marketing to the uninformed sense) and structural advantages, there is no practical advantage to the design, or at least (again) it is very difficult to realize the theoretical advantage of two fewer vortices.
Not meant to discourage -- you asked. Most models are by definition 0% efficient anyway, since they burn fuel and do no useful work
.
The wings are often staggered to mitigate the significant interference drag between panels joined at less than a 90 degree angle. Unless the panels are staggered (by opposing sweep), the interference drag can far exceed any gains made by elimination of one pair of tip vortices. There will then be losses near the joint caused by the leading wing influencing the trailing wing's local AOA, in turn creating drag and low-speed handling problems. The trailing wing would have to have an unusual twist distribution to account for this without massive increase in induced drag (due to highly non-elliptical CL distribution along the span), and then it would only be "correct" in one flight condition, unless the geometry was variable in flight.
It is complex to design a truly efficient joined-wing airplane (ultimately it would require CFD and wind-tunnel testing). This is why there are few full scale examples of joined-wing craft, other than biplanes.
Dick't right again: A biplane with interplane struts is generally the best form of joined-wing craft, since the panels are joined at 90 degree angles, minimizing interference drag.
Aside from looking cool (in a marketing to the uninformed sense) and structural advantages, there is no practical advantage to the design, or at least (again) it is very difficult to realize the theoretical advantage of two fewer vortices.
Not meant to discourage -- you asked. Most models are by definition 0% efficient anyway, since they burn fuel and do no useful work
.
