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Old Apr 17, 2008, 11:39 PM
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How to make wing ribs

My easy sport recenty had a close encounter wth the ground, and was somewhat damaged, and I want to rebuild it, the fuselage will be new, and the wing is one half complete ; I got the plans froma good friend and want to do the repair myself, but I am having problems making the ribs, what is the propper technique to do this? I would like to build a couple of planes from plans as well, but the ribs seem to be the hardest for me, any help is appreciated.

regards
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Old Apr 18, 2008, 02:32 AM
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Here is an article on how to make ribs using the block-technique.

Individual ribs for repairs I cut roughly with a balsa knife and then sand to shape, constantly comparing to plans. You can also copy the plan, and stick it to the balsa, then cut.
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Old Apr 18, 2008, 09:15 AM
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Since your Easy Sport has a constant chord planform, making multiple ribs as shown in the article is certainly a workable approach.

I use counter laminate (formica) for my templates. It's hard and I can also use it for making foam core templates. The easiest method I've found for making the master template is the same as in the article and like MarkusN -- copy that portion of the plan and glue the rib profile to the laminate. I cut as closely as possible to the outline with a bandsaw, then finish up with a file and sandpaper block. Spar notches are also cut with the bandsaw. I also write the airfoil identifier or plane on them for future reference.

For just a few ribs, I've found it to be just as fast to hold the template on the balsa and cut around it with an Xacto knife. Generally, I cut the spar notches with a single edge razor blade. After all the ribs are cut, I align them with short pieces of spar stock and finish sand to shape. If the template tends to slip around, glue fine sandpaper to the backside -- it won't move at all.

I've used the same technique that the article shows for many years -- I hate cutting ribs and it makes it a little easier.
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Old Apr 18, 2008, 10:06 AM
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Thanks

Thanks i'll try both approaches.

Regards,
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Old Apr 18, 2008, 10:21 PM
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A friend with a cnc router or laser is always a good option!
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Old Apr 18, 2008, 11:59 PM
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Hey guys, on a similar subject, how would one make wing ribs for a wing that tapers on all 4 sides (front, back, top and bottom) I could do it the easy way and photochop my one known rib down to scale as a function of the chord at the point I choose. But I hate using computers to do stuff, things come out funky. Im building a Yak 55 by the way, but its wings are similar to an extra 300 as far as tapering from a large airfoil to a small airfoil but they are both the same airfoil, just different sizes.
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Old Apr 19, 2008, 01:47 PM
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The stack cutting technique described in the article referenced in post #2 works ok for moderately tapered wings with similar root and tip airfoil sections. If the taper ratio is very high or the root and tip are radically different you'll need to loft the sections and cut the ribs individually. Lofting by hand is pretty tedious but if you don't want to do it the easy way you can learn it from a drafting book. However said book will cost you more than software
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Old Apr 19, 2008, 07:13 PM
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True, I think I might take a trip to the library then!

I discovered I could use a program on my computer to make ribs however I want them..but it's kinda annoying since its using a Bezier curve instead of a true airfoil program.
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Old Apr 19, 2008, 10:32 PM
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Quote:
Originally Posted by ziomatrixacs
I discovered I could use a program on my computer to make ribs however I want them..but it's kinda annoying since its using a Bezier curve instead of a true airfoil program.
May I suggest that you look into Profili II . It comes with about 2200 proprocessed airfoils, is quite versatile, allows you to automatically loft ribs, create foam cutting templates and a host of other features. Cost is around 10 euro and worth every bit.

www.profili2.com

There is also a plans page included in his site.

andrew
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Old Apr 20, 2008, 12:06 AM
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Thank you for the suggestion, I checked it out and it looks like it would work but I am using a Mac. It appears to be Pc only.

I could, in theory, take a jpeg of an airfoil off the internet and use Omnigraffle to trace over the outline with a Bezier curve then I could look on my physical planes. Say the root rib is 10 inchs, and my tip is 5 inchs at 20 inchs apart. I could do a little trig or just measure the span at where I want the rib to be. So just say half way down the wing, at 10 inchs, the chord is 7 inchs. I could find the ratio of how large the root rib is to that rib, then enlarge it until the picture on my computer says the rib is 7inchs long. Print, test fit, and then do the usual thing. It outta work..if not, then I only use a few minutes of my time since I have learned how to do airfoil shapes (not necessarily a real airfoils) I will report back as soon as I get my wing built!

Thanks again for the suggestions.
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Old Apr 20, 2008, 07:00 AM
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Originally Posted by ziomatrixacs
Thank you for the suggestion, I checked it out and it looks like it would work but I am using a Mac. It appears to be Pc only.
Yeah. I wanted to ditch my PC as well. So I got my wife's old Mac, put OSX on it and then thought:-

"How hard can it be to get the equivalent of Corel Draw and Motocalc on a MAC, and hook up my HP scanner and 24" paper inkjet?"

The short answer was, that it was, in fact, impossible: When I pointed this out to Mac afficionados on the Net I was shouted down as a PC troll.

I managed to find a turbocad sort of demo that almost worked OK, but it wasn't a patch on Corel for Laser design. And it dint do decal artwork. The adobe suite worked well but only for graphic design, and cost a lot of money. No combination of drivers managed to make the big inkjet work reliably, and the scannner only worked with a third party unfree program. And that only in isolation. You couldn't import directly to a graphics program.

The power PC G4 on 1GB RAM runs a shade slower than the old PC on 512Mybte on XP.


The sad fact is that Mac's are for people who don't use computers in a serious way: They are great home computers, and they do typsetting stuff really well, but they have zero third party support in almost any other specialist area. And what they have comes very expensive.

If you want to do model aircarft design, you need an INTEL MAC, boot camp or parallels, and a copy of windows. Or do as I did and put together a scrap PC from old hardware. And use that. Here in the home office, I have the Mac, which is fine for word processing, spreadsheet, mail and web browsing, but its useless for models. The model PC is in the workshop, connected to the scanner and the big inkjet, and there is another old PC put together from scrap running LINUX as an office file server, and web server.

It works for me...
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Old Apr 20, 2008, 09:36 AM
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Interesting. I am running a G4 ibook with 1.2ghz power pc processor and 256mb of ram. I needed a computer to do my homework and stuff on. My friend got a new macbook and didnt want this thing any more so I bought it for a couple hundred bucks. My alternate was a dell with almost the same specs but it was refurbished and selling for $500 around christmas. So I just went with the better deal considering I could have got a HP with like 1-2 gb of ram and much better processor for around $650 at the time.

I like it though.

I do agree there really isnt any software support for building models on a mac, but I prefer to do things the old fashion way with a sheet of paper and a pencil. The program I use is called omnigraffle. Its like MSpaint but its actually designed for flow charts I guess. It allows me to make shapes and define their size and position by punching in numbers, and it has an aligning grid. It only lets me have 20 shapes though unless if I buy the $40 licence. Im sure there are other programs but this one allows me to draw the same way I do on paper, but a bit more precisely. Then I can print it out on multiple sheets and build off it. I usually get annoyed with havving to do a lot of clicking but this program is really comfy..
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Old Apr 20, 2008, 11:19 AM
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There is a version of Qcad for Mac OS 10.4 It lacks many of the editing features that a professional drafter would be used to but it's good enough for home use especially if you're on a budget. And the splines are NURBS.

--Norm
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Old Apr 20, 2008, 11:29 AM
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Stuff it with a gig of ram and it will do more.

Not a bad processor at all, on OSX anyway.

But a scrap PC will be more use modelling wise..and there is a lot of ..ahem..pirate software out there..if you want to try stuff out ..and a three to four year old legal copy of e.g. Corel Draw won't break the bank either.

Most of the computers I am putting together these days are recycled 'its not fast enough' stuff that people have found wont run Vista etc. Get windows 2000 or XP and an old PC, shove half a gig of RAM in, and get some 4 year old software for it. Not hard, and very very useful.


I've got XP, CorelDraw 12, open office for WP and spreadsheet, Thunderbird mail and Firefox browser, and Motocalc on my 'model' PC. Ive also got turbocad, for compatibility, but I don't use it.


Only XP, Corel and Motocalc cost anything, and they weren't much. Well obsolete! Except Motocalc of course.

Corel draw is the bees knees for 2D draughting as it covers everything from bitmap maniplation through decal design up to mathematical CAD.

Rhino 3D would be ideal but it costs a small fortune.

And needs more machine to run it!

You can pick up 24" inkjet roll printer for less than 500 on ebay too.

To be honest if I had to put a new machine together it would be simply 'what is the best machine to run Corel Draw /Rhino on?" and leave the rest to chance..
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Old Apr 20, 2008, 11:45 AM
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Q cad looks like it would work but I don't feel like spending $32 on it at the moment... I tried google sketchup and it does what it does, but its a pain in the butt to get it to do that with any precision. Its good for just chalking up a concept.. not sure why but even then I still prefer a sheet of paper. Unfortunately most employers would rather have you work with CAD instead! Ill try the Demo and then will consider buying it..

What about adobe photo shop? I know that cost some serious money but what does it do exactly? I know it edits pictures but I hear its the swiss army knife of its class.

Either way, I need to get a comfy mouse first. I so used to drawing with a pencil that it actually hurts my wrist to use a mouse to draw. I would look for specialty pen style mouse but Im sure if they make them, they arnt cheap. I think I might get a cheap micro laptop mouse and try to get it to fit into a pencil shape or something of the nature..
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