Which is lighter?
 

which is lighter?

Foam wing or the equivalent sized ribbed wing?

RE: Which is lighter?
 

Depends on how the ribbed wing is built and wood selection.
I can usually build lighter foam sheeted wings using contest grade balsa than I can build a ribbed wing. I can always build a straighter foam wing. Wood selection is key to both however.

RE: Which is lighter?
 

The "average" built up wing tends to be lighter than the "average" foam core wing. However with some special building techniques such as lightening holes in the foam, and very judicial glue usage, the foam wing can be built as light as a good light weight built up wing. Notice my use of the word "average".:)

RE: Which is lighter?
 

Which size wings are the target ?- and why not Fiber-Glass ones to compare with ?
It looks to me for thick (pattern-flying) wings the Foam is maybe(?) not the best solution, but
it might be better if someone wants to have hard-surface by oter reasons and monocote is
not so robust for that. I like the smooth, exact(!) surface of the foam wings but almost no one
is making them arround at low cost. Could you name some not-too-expensive foam wings
one can get from the main RC suppliers ?

RE: Which is lighter?
 

Hi Mtcarey

It is similar.

For two pieces wings :
I did wings foam/balsa sheet, ribbed wings. So weight is about 450 g (15,87 onces) totaly finished (oracover, servo, quick link ..) without carbon tube
I had composite wing (painted in the mold) planes Rhapsody and Cocaine. Weight are 470 g (16,58 onces) with servo, quick link ...

There is an exception as one piece wing made by CPLR foam and brown paper (weight about 700/750 g (24,7/26,45 onces).
Claude

RE: Which is lighter?
 

In my experience, with a foam wing and a built wing of equal weight, the foam one will be a little stiffer.

RE: Which is lighter?
 

I'm starting to think also that foam wings tend to be "quieter" which may be a concern if you're building an IC powered ship.



wait, I take that back, I'm not starting to think, I "know"

RE: Which is lighter?
 

I have built foam wings ready to fly at 12.5 oz and so have many others.

Personally, strength and weight favor the foam wing by far. Unless you dont sheet the entire balsa structure, could save weight there.

Chuck Hochhalter

RE: Which is lighter?
 

I think alot of it is to so with construction times, Foam is quicker and easier to build. I do not think a foam wing would be any lighter or stronger than professional built built up wing. But the built up wing would probably take four times longer.

RE: Which is lighter?
 

For what it's worth Ola Fremming has a great descripion on how to cut even more weight out of a foam wing after vacuum bagging.

http://www.ofremmi.info/HowTo/WingLi..._foam_core.htm

RE: Which is lighter?
 

This hadn't occurred to me before, but to anyone who has played an acoustic guitar, and an unplugged solid electric guitar it makes a lot of sense. It probably is not as much of a concern with electric, where the vibration is less.

RE: Which is lighter?
 

Again, this is a difference between IC and electric, where you can get away with a lighter wood structure on an electric.

RE: Which is lighter?
 

I have built foam wings, and built up wings, and have found that foam isn't really that much faster if the built up is from accurately laser cut parts. Back in the days of die cut kits, getting everything to fit properly was very time consuming. Cutting a scratch built set of ribs on a band saw? Forget it. Of course the caveat is that the laser cut parts must be very precise, and you need a good jig.

With foam, you still need to cut the core. If it is hand cut, and both sides are not absolutely identical it becomes a real pain. I sheeted 12 sets of wings for a guy one time and the thickness varied by as much as 1/32 inch. If they had been CNC'd, I could have done them in half the time. And you still have to trim and edge glue the sheeting. Glue it and vacuum bag it. Cut out the ailerons, hinge them, cut, etc. servo pockets. I can assemble a good laser cut wood wing almost as fast

RE: Which is lighter?
 

Hi Dave


I aggree with you. Also with 2 pieces built up wings it is easier to install carbon tube.
Now for friend of mine I 'm doing 2 pieces wings for plane Nebula as shown on pics below :
2 last pics are shoot on french championship.
Claude

RE: Which is lighter?
 

Wow . . the Nebula looks NICE !

For interest, pics of my Wind S Pro 'built up' wings . . 348.9g (12.3oz). Both wings are within a gram of each other.

JB

RE: Which is lighter?
 

Hi Jeff

Is that each wing? My foams wings came out at 850 grms, which I think was pretty good seeing as I wasn't keeping check on the weight.

Just looking at the photos of your plane, are they composite wings or built up balsa skinned?

Nice photos too Claude.

What type of material is the ribs from on the model you are building. Is it light ply or balsa, also what width, is it 1/16 or 3/32 or 1/8?

Cheers?

RE: Which is lighter?
 

Yep, you got it!

RE: Which is lighter?
 

That was the weight for one wing, so approx 696g for the pair . . The wings are built-up ribs and fully sheeted, covered with Oracover.

JB

RE: Which is lighter?
 

Hi Foofydoo

There are 17 ribs. 15 are made of normal balsa 2 mm (0.079 "). Rib number 1 and 5 which support carbon sleeve are made of 3 mm light plywood (0.118 ").
Note that there is a litle bit difference between 2 airfoils. May be it's real or suppose due to the cutting foam or the drawing I did with my pencil !