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Ribs profiles - assistance.

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mjcp
Posts: 175
Joined: 29 Jul 2015, 08:14
Location: A wind swept hill with no wind, in driving distance of Windsor, UK
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Ribs profiles - assistance.

Post by mjcp »

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
m̶j̶c̶p̶ Marc

Hanger -
Some (now) pristine models that are un-flown for a year.

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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Ribs profiles - assistance.

Post by Peter Balcombe »

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

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mjcp
Posts: 175
Joined: 29 Jul 2015, 08:14
Location: A wind swept hill with no wind, in driving distance of Windsor, UK
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Re: Ribs profiles - assistance.

Post by mjcp »

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
m̶j̶c̶p̶ Marc

Hanger -
Some (now) pristine models that are un-flown for a year.

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Peter Balcombe
Posts: 1410
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Ribs profiles - assistance.

Post by Peter Balcombe »

Marc,
Is this the sort of thing you mean?
Attachments
Marc ribs.jpg

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mjcp
Posts: 175
Joined: 29 Jul 2015, 08:14
Location: A wind swept hill with no wind, in driving distance of Windsor, UK
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Re: Ribs profiles - assistance.

Post by mjcp »

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
m̶j̶c̶p̶ Marc

Hanger -
Some (now) pristine models that are un-flown for a year.

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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Ribs profiles - assistance.

Post by Peter Balcombe »

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.

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chris williams
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Location: Blandford Dorset

Re: Ribs profiles - assistance.

Post by chris williams »

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)

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Barry_Cole
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Joined: 10 Mar 2015, 09:30
Location: Hampshire UK

Re: Ribs profiles - assistance.

Post by Barry_Cole »

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...

:twisted: :twisted: :twisted: :twisted:

BC

Jilles
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Joined: 22 Mar 2015, 10:27
Location: Australia
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Re: Ribs profiles - assistance.

Post by Jilles »

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

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Peter Balcombe
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Re: Ribs profiles - assistance.

Post by Peter Balcombe »

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

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