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Author Topic: Making Ribs And Half Ribs  (Read 1379 times)

Offline Motorman

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Making Ribs And Half Ribs
« on: January 11, 2020, 03:56:30 PM »
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« Last Edit: August 27, 2021, 08:19:28 AM by Motorman »
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Offline Avaiojet

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Re: Making Ribs And Half Ribs
« Reply #1 on: January 11, 2020, 05:16:58 PM »
Stacking may not work as well as you think.

Just a suggestion, but you could do as I have sometimes done,

That is, to make all ribs, except the root and tip rib, over sized. A quick cut using a #11. Then build the wing. One advantage is the rough cut ribs will have a square end.

Tape the root rib and the tip rib tops and bottoms then "T" bar sand away. Yes, you have to pay attention to the airfoil shape and maintain it while sanding.

I've done full wings this way. the Stuka and I repaired my P-40 this way also. It does work.

This method may not be meant for everyone.

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Offline Avaiojet

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Re: Making Ribs And Half Ribs
« Reply #2 on: January 11, 2020, 07:26:28 PM »
Quote from: Motorman on January 11, 2020, 06:39:39 PM
Interesting idea but on the first go round I will only know the tip and root so it's hard to cut out ribs with no patterns.

This is why you make them chubby except for the length.

Make them all the thickness of the root rib.

This method works fine.

See.

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Amazing how ignorance can get in the way of the learning process.
If you're Trolled, you know you're doing something right.  Alpha Mike Foxtrot. "No one has ever made a difference by being like everyone else."  Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten. "No amount of evidence will ever persuade an idiot."- Mark Twain. I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.   Proverb 11.9  "With his mouth the Godless destroys his neighbor..."  "Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Online Paul Smith

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Re: Making Ribs And Half Ribs
« Reply #3 on: January 11, 2020, 08:19:03 PM »
Stack standing.

I use 4/40 threaded rod for the long bolts.  For alignment, I drill two holes in a block of wood with the drill press.  Using two 1/8" rods I get the stack straight.  I keep the stack straight with a bit of clear dope holding the blanks in line.  I put the dope in the sanded-off area so there isn't much to cut or dissolve when I'm done.

For tapered wings I do them all at once, with the an odd rib going in the inboard (longer) side. 

I haven't considered the issue of half ribs on a taper wing.  But throwing away half of each rib isn't an option that I would accept.  Maybe a second stack sanding with the half ribs would be close enough.
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Offline pmackenzie

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Re: Making Ribs And Half Ribs
« Reply #4 on: January 11, 2020, 09:18:59 PM »
I do it the lazy man's way - but might not be easy for everyone.
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Online Fredvon4

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Re: Making Ribs And Half Ribs
« Reply #5 on: January 12, 2020, 07:15:41 AM »
Find any current airplane model with near identical wing and buy the laser cut rib set

Brodak
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not sure why a Phil Cartier or Bob Hunt cored foam wing would not work
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Offline Serge_Krauss

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Re: Making Ribs And Half Ribs
« Reply #6 on: January 12, 2020, 10:13:59 AM »
An alternative:

Profili software is very inexpensive and requires no particular skills to use. If you tell it the root and tip chords and how many ribs you want, you can select a wing section from its library or make your own. It will generate all the ribs in between. You can use differently shaped sections for root and tip, and it will interpolate, giving you the progressively-changing ribs between. It can also be made to create recesses and cut-outs for spars, lead-outs, lightening holes, etc. It does elliptical wings too. Once you have this tool, you will always be able to do this simply. When building from plans, you'll often find that the designer has used an NACA section from the library.

It's worth the effort to get it and just use it when needed.

SK
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Offline pmackenzie

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Re: Making Ribs And Half Ribs
« Reply #7 on: January 12, 2020, 10:50:56 AM »
Quote from: Motorman on January 12, 2020, 07:30:27 AM
There's no plane like it and can't use foam because it's too heavy for 1/2a and lost foam is too expensive for 1/2a.

Pat, don't you need a set of ribs to set up that cutter in the first place or do you design it all on the computer? Either way I'm envious.


Motorman 8)

Designed on the computer. I use a combination of CAD and Compufoil3D.
The latter saves a lot of CAD time, and can do some things that are harder in CAD, like tweaking the initial root and tip sections.
For example shifting the high point a bit or changing the trailing edge thickness is very easy in Compufoil.

Lost foam can be a DIY thing and not expensive, just cut a blue foam core, and slice it to get the rib stations.
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Offline john e. holliday

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Re: Making Ribs And Half Ribs
« Reply #8 on: January 12, 2020, 11:37:20 AM »
I make my half ribs the same time I make the full ribs with the ply tip and center rib pattern.   The rear bolt/rod has scrap balsa between the full ribs.   Yes cut all a little over size and carve/sand to the ply templates.  Before removing bolts/rods mark top side of the ribs.  I also don't cut the spar notches until the ribs are attached to leading and trailing edge.   Don't for get to number the ribs and mark inboard/outboard. D>K
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Offline Randy Powell

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Re: Making Ribs And Half Ribs
« Reply #9 on: January 16, 2020, 03:16:32 PM »
I tend to go to Pat Johnston and have him laser cut me a set of ribs. I give him the root and tip ribs, tell him how many ribs and he sends them to me in a tube.

But hey, I'm lazy these days.
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Offline Brett Buck

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Re: Making Ribs And Half Ribs
« Reply #10 on: January 16, 2020, 04:42:32 PM »
Quote from: Motorman on January 16, 2020, 02:52:53 PM
So, if your wing is longer on the inboard side you have to make the inboard and out board ribs separately?

   You have to do that anyway, you can't stack both sides at once.

    Brett
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Offline Leester

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Re: Making Ribs And Half Ribs
« Reply #11 on: January 18, 2020, 01:37:10 PM »
Can't be that much difference, assemble without R2's in place then adjust them to fit.
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