Piaggio P180 Avanti scratch build previously "Foam choice for a scratch build...

[sihinch]

I think you need more beer, Bill!!

[Papa]

Here are some Clark Y images. You could modify it by giving the bottom some lifting characteristics.

Jack.

[Andy Hoffer]

Here are some Clark Y images. You could modify it by giving the bottom some lifting characteristics.

Jack.

Looks like a whole school of Pike !!!

A

[piker]

My approach for choosing airfoils sections for scale models (not that I've done it very often) is to browse through Profili until I find a section that looks reasonable close to that shown on the three view.  In the case of the Sandringham, I did that then chose to reduce the thickness to 15% from the scale 18% or 20%, as I recall, to reduce drag.

However, anytime I've done this, the scale section looked reasonable so I didn't see any risk in this method, but if you say the Piaggio has a strange section, then going with the good old Clatk Y is a great option.  I remember Keith Shaw saying that he would use the Clark Y on all his planes.

[Wingnutz]

Clark Y it is...the 3-view is no help at all. I will incease the wing size slightly...my plan is to add 1/4-1/2" all the way around. Hopefully that will not lose the character of the full size wing. Thanks Jack, Rob, for your help. I'll cut the templates today and dust off(there even more dust than usual right now!) the hot wire stuff.

[Tom M.]

There should be no dust Bill cause you're vacuuming every few minutes, right?
  Tom

[Wingnutz]

There should be no dust Bill cause you're vacuuming every few minutes, right?
  Tom

Well, a lot more frequently tha before your earlier post!

[Wingnutz]

Cut some templates for the wing and started to lay it out on the magnetic building table. Used Jack and Rob's suggestion and used a Clark-Y airfoil. This is really easy to work with...the bottoms are flat and sit nicely on the table! (Unlike my last scratch built wing which had a scale symmetrical airfoil and wouldn't sit still on anything!)
Increased the wing approx. 1/2" in chord and span. It still looks ridiculously high aspect ratio!
Used 1/8" ply for the templates and I got tempted to cut a bunch of balsa ribs and frame and sheet the wing with balsa but I think I'll stick with the original plan to hotwire foam cores. I may not even sheet them for the first few flights until I get the CG and incidences right...foam's easy to fix!

[piker]

Bill,

How does the wing section transition from the center section to the outer portion.  It looks like an abrupt change.  Is the step hidden under the nacelle?  You'll have to consider the structural consequences of this set-up when designing the wing.  You'll have quite a stress riser there.

Robert

[Wingnutz]

Rob, Thanks for noticing...I need all the help I can get with the wing (everything else too!) design! Plan (not yet cast in epoxy) is to run a spar or spars (3/16"?) through the centre section, angling to create the 2-3degrees dihedral where the wing joins the fuse. I will either cut the ply spars as single pieces or gusset the angles. This section will remain attached to the fuse and will include the nacelles. Wing sections outboard of the nacelles will be detachable...I might rethink the detachable part if I go for the flaps outboard of the nacelles.
I will be thrilled to have my plans revised or re-written by anybody with a great build and fly track-record like yourself. Hoping for suggestions!
Bill

[Wingnutz]

Back to the build I today. (Too busy yesterday trying to "work with" the club photographers! Hard work! They're demanding guys! Well, one of them anyway!)
Started building the centre section (one section, three foam pieces, three spars) of the wing...at least a trial of this part. As you can see from the increase in a Canadian content, this was hard work and involved a lot of head scratching and bottle opening.
Anyway, pulled out my hotwire cutting stuff and after a discussion with Andre who knows about electricity (I don't), I discovered my power source is kicking out AC  current...better consume the Canadian content after I do the hotwire cutting and buy a new power source before I electrocute myself and/or burn the house down!
Managed to get the three centre wing pieces of foam cut and slotted, the spars cut (balsa for now, ply later) and trial fitted with about 3degrees dihedral. Choosing the Clark Y airfoil has again proven a joy...everything in the bottom lines up in one plane!
Now that I know some of the problems trying to build the wing this way, I'll probably go back and do it again
more accurately.
Any suggestions appreciated, especially how to cut the faces of the centre section at the right angle to match the three degrees dihedral of the outer sections... I'm still "winging" it!

[Ededge2002]

The model is looking great Bill and I love the form. In your comment about finding CG and flying characteristics you might take a look at the multiplex sonic liner. Its not a match for your plane but it might give some insight.  I think your concerns of the high aspect wings will be resolved. High aspect ratio wings make proportionally more lift at less drag than there stubbier relatives. All plusses for you in this case as less power will be required to push it through the air allowing less power system weight!

http://www.google.ca/search?biw=360&bih=293&tbm=isch&sa=1&ei=O1LcUtDwHIywqwGJhICADg&q=multiplex+sonic+liner&oq=multiplex+sonic&gs_l=mobile-gws-serp.1.0.0i24l2.26868.31978.0.33473.16.15.0.1.1.1.171.1754.1j11.12.0....0...1c.1.32.mobile-gws-serp..4.12.1666.meWVv44dmns

[Wingnutz]

Wow! That is one wonderfully unique configuration! My browser went straight to the images and...wow! Gonna see ifj I can still find one! The general layout is similar to what I'm trying to build.
Thanks for the link. Good to hear from you!

[Wingnutz]

Trial fitted the wing. Lots more work here but I wanted to see the inboard part of the wing in place. Time for bed.

[piker]

That wing sure does look small but it's looking very cool

Now go nurse that hang-over