Scale Soaring UK

Can anyone lend a hand?

I'm after a rib plot of a wing, with tabs / locating feet / base tabs etc to get the correct dihedral and sweep.

No doubt there's a few questions, but the basic wing is:

Span (single wing) 700mm, (there will be 100mm fuse between them, the root will be extended within the fuse)

Sweep 3.5Degrees (Leading edge)
Dihedral: 0
Washout: 0

Root: SB96V
Chord: 342mm

Tips: SB96VS
Chord: 210mm

M

Mark,
I could knock up the basic wing on DevWing if you like.
The SB96 airfoil coordinates appear to be available on the web, so probably just needs an indication of your preferred rib spacing unless you also want provision for spars, joiners etc.
Simple to provide front & rear building tabs & if no dihedral or washout then can setup for building parallel to building board.
PM your email address unless already available on the forum system.
Peter

Email sent. I don't appear to be able to attach and image of the plan view... hey ho.

To add, rib spacing on the plan (for a built up wing) is ~55mm

Thanks,

Marc

Marc,
Is this the sort of thing you mean?

Yup!

Then I can print and hand cut. The tabs will keep the sections aligned while the top surface is created and a spar fitted, then once that's sorted / solid, over it goes for the bottom to be done!

M

Marc
dxf files are on their way to you.
Interestingly, DevWing already had the 2 sections in its airfoil database, plus a few more of that ilk
Root is 9.35% thick, 1.25% camber, whereas tip is 9.75% thick with same camber.

mjcp wrote: ↑15 Apr 2021, 18:01 Yup!

The tabs will keep the sections aligned while the top surface is created and a spar fitted, then once that's sorted / solid, over it goes for the bottom to be done!

M

I've always struggled to understand this method... Once you've removed the tabs, how do you keep the wing straight when adding the bottom sheeting?

(Someone probably explained to me once, but now I can't remember)

chris williams wrote: ↑15 Apr 2021, 19:40

mjcp wrote: ↑15 Apr 2021, 18:01 Yup!

The tabs will keep the sections aligned while the top surface is created and a spar fitted, then once that's sorted / solid, over it goes for the bottom to be done!

M

I've always struggled to understand this method... Once you've removed the tabs, how do you keep the wing straight when adding the bottom sheeting?

(Someone probably explained to me once, but now I can't remember)

By using the Quantum of Solice. Please try and keep up...



BC

here is an option
You turn the wing upside down , do not remove the tabs. Then make supports to fit the top of the wing at say the root, the tip and two more in between those at roughly equal distances. check with a level if the tabs are still in line and level
Secure the wing on the supports, remove the tabs and do whatever you need to do on the wing bottom.

You can also make the new supports when the wing is still on the tabs. make sure the top of these supports that later will rest on your building board, are on a plain level,.then turn over the wing.

On one or two of my glider designs I have these supports included in the Laser cut kit made from 12 mm balsa sheet. . it is an extra expense that one want to invest in or not

Some built-up wing design programs (e.g. DevWing) also give the option to produce top and/or bottom surface building jigs to rest the wing structure on whilst skinning.
However, as Jilles says, it’s extra expense & wood.
Peter

This is my preferred method; easy to draw on the PC, and as you can see, expensive it is not, even at today's balsa prices!
Sheet the bottom, lay wing on jig supports and sheet top...

The PSSA Mass build Sabre used a similar method to include the dihedral and washout into the wing build:

It's worth remembering that a wing is not torsionally rigid until all three elements of the D-section are in place...(web plates, lower sheeting, top sheeting) Thus, when adding the lower sheeting, for instance, it really doesn't matter if the wing is flat or not. It's not until it's jigged up and the top sheeting added that the wing becomes fully rigid...