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  • June 21, 2021, 02:11:06 AM

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Author Topic: Making Rib Sets  (Read 534 times)

Offline Ken Culbertson

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Making Rib Sets
« on: June 09, 2021, 02:47:04 PM »
I have time on my hands so I know that either of the options I am asking about are not the most efficient approach but, I need to make a rib set for my own airfoil.  It is basically the Thundergazer with an additional 1/8" thicker TE to house recessed flaps.  I have two options.

1. Draw and cut out each rib individually which I can do but I would really like to find a cheap CAD program to draw them so that I can find someone to laser cut a set.

2. The old sandwich method which usually ends up with some tilted cap strips.  Should I select this option, and it is looking like I will, I would like an opinion on something I have done once n the past.  When I stacked the blanks, I did both sides at the same time then alternated the ribs inboard/outboard.  This resulted in the inboard wing being approximately 1/32" thicker.  To compensate I did not offset the centerline. I didn't notice anything different about how that plane flew compared to others with unequal spans but the same thickness.

Ken
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Offline Motorman

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Re: Making Rib Sets
« Reply #1 on: June 09, 2021, 03:13:10 PM »
If you're making a true Thundergazer wing with the Warren truss ribs, stacking won't work. Also, it is very critical to line up the leading edge perfectly straight which requires near perfect rib cut outs and is hard to do without the lost foam system.

Motorman 8)
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Offline Ken Culbertson

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Re: Making Rib Sets
« Reply #2 on: June 09, 2021, 03:41:16 PM »
If you're making a true Thundergazer wing with the Warren truss ribs, stacking won't work. Also, it is very critical to line up the leading edge perfectly straight which is hard to do without the lost foam system.

Motorman 8)
No, it will be a classical "C" tube build with a molded LE.  The Airfoil I have used since the 60's, with minor tweaking, is very close to the Thundergazer.   

Ken
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Offline pmackenzie

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Re: Making Rib Sets
« Reply #3 on: June 09, 2021, 05:12:42 PM »
Have a look at Compufoil.
It is not that expensive, and simplifies a lot of the tasks involved in doing a set of ribs.

http://www.compufoil.com/product_cf.shtml


You can get the free version and play around with it to see if you like it.
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Offline Ken Culbertson

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Re: Making Rib Sets
« Reply #4 on: June 09, 2021, 06:57:17 PM »
Have a look at Compufoil.
It is not that expensive, and simplifies a lot of the tasks involved in doing a set of ribs.

http://www.compufoil.com/product_cf.shtml


You can get the free version and play around with it to see if you like it.
Thanks, this looks like exactly what I want.

Ken
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Offline John Miller

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Re: Making Rib Sets
« Reply #5 on: June 09, 2021, 08:38:14 PM »
I've used Compufoil" for over 20 years now, and believe it's one of the best. There may be a bit of learning required but there are popups available, built intro the program. Over the years the program has gotten stronger, and more capable. The program comes packed with a huge airfoil selection. It also has a NACA generator that will allow you to generate nearly any NACA based airfoil.

With the help of the program you can modify any airfoil, almost any way you desire.  I tend to use one of 4 airfoils for stunt use. a NACA  4 digit,  a NACA 6 digit that I've modified, a Pathfinder "Ice Cream cone" Combat style, and an Eppler 169 symmetrical foil that seems very good. I can change almost every possible feature and can usually come within a pencils line width of matching most any airfoil. It is possible to enter in your own airfoil.

There are several very good options  when it comes to lofting the wing. My most favorite lately has been the ability to create wings with the Warren Truss style ribs. I've lofted several true elliptical warren truss wings for a design I've been working on.

Getting the free version for learning on may be a good idea. If  you begin to understand how it works, you'll want the fully loaded version I use. It is always update-able for free.

John Miller

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Offline Motorman

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Re: Making Rib Sets
« Reply #6 on: June 10, 2021, 06:48:45 PM »
I have to admit i downloaded the free version but I'm dumb on it. Can't get it to do anything.


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Offline pmackenzie

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Re: Making Rib Sets
« Reply #7 on: June 10, 2021, 06:54:42 PM »
Like anything else, there is a bit of a learning curve :)

A video might help:



Once you get it to do something, you will get a better idea how to do other things.
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Offline Dennis Toth

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Re: Making Rib Sets
« Reply #8 on: June 11, 2021, 06:01:22 AM »
Ken,
Other option is to find a ship that is close enough for the wing style you want and order a set of laser cut ribs (Brodak has them for all their kits), then design around it for the ship you like. I have ordered several rib sets and it is well worth the money and time saved. Also could look at Bob Hunts lost foam approach as I think he could offer the core cut for the warren truss to give you rib templates.

Best,    DennisT

Offline Ken Culbertson

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Re: Making Rib Sets
« Reply #9 on: June 11, 2021, 06:20:39 AM »
Ken,
Other option is to find a ship that is close enough for the wing style you want and order a set of laser cut ribs (Brodak has them for all their kits), then design around it for the ship you like. I have ordered several rib sets and it is well worth the money and time saved. Also could look at Bob Hunts lost foam approach as I think he could offer the core cut for the warren truss to give you rib templates.

Best,    DennisT
I have done that with a Brodak set that was close before and I agree it was well worth it.  I looked through their set and didn't find anything close to the Thunderbolt/gazer.  If what I am building now were not a "classic" I would do the lost foam but it isn't.  I am stretching it as much as I can internally but I think the Warren truss might be a bridge too far.  I do think it might be a good idea though to get a lost foam mold for my PA design before he retires again.

Ken
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USAF 1968-1974 TAC

Offline Motorman

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Re: Making Rib Sets
« Reply #10 on: June 12, 2021, 09:36:32 PM »
The video helped, I got it to do something!

Couple of questions, can it make templates for warren truss ribs? On the Thundergazer wing some ribs are straight but not spaced evenly and some are angled. Will it do all that? 

Thanks,
Motorman 8)
« Last Edit: June 12, 2021, 10:19:24 PM by Motorman »
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Offline pmackenzie

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Re: Making Rib Sets
« Reply #11 on: June 13, 2021, 05:46:29 AM »
To do geodetic ribs you need the paid program, with the $21 lofting option add on.
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Offline Serge_Krauss

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Re: Making Rib Sets
« Reply #12 on: June 13, 2021, 06:51:14 AM »
Profili is a good option. It comes with a wide variety of extra functions, but the old basic has been sufficient for me to accomplish what you want to do.


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