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bcchurch
Joined: 10 Dec 2007
Posts: 25
Location: Racine, WI
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 Posted: Wed Sep 17, 2008 6:54 pm Post subject: 801 wing root rib |
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I'm working on the right wing and ran into a problem with the root rib. When I locate the root rib, the rear spar deflects rearward 6 or 7 mm. The distance between the main spar and rear spar at all of the rear wing ribs is 820 mm. At the root rib, I get 827 mm. Now, the IB bottom skin is 820 mm wide which tells me that all the ribs are looking good except for the root rib.
I'm discussing the issue with Caleb but wanted to ask some of the 801 builders here a few questions:
1) is the root rib parallel to the other rear wing ribs?
2) is the root rib the same length as the other rear wing ribs?
3) does the root rib join the rear spar at the 1st or 2nd row of pre-drilled holes in the rear spar? (My pre-drilled skin tells me the first row in the rear spar is correct).
Without your parts in front of you, I realize it's a pretty small detail and probably hard to answer. I've attached an excel file with some measurements and notes to help describe my problem.
I suppose there are some that would say I'm nit-picking over a few mm. But, when I get that root rib in place I really see a curve in the rear spar between the root and station 1 and I just don't like that.
Thanks,
Ben
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Ben Church
CH801
Racine, WI |
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jgswartout(at)gmail.com
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| Posted: Thu Sep 18, 2008 2:49 am Post subject: 801 wing root rib |
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Dear Ben,
You are absolutely correct to nitpick about millimeters in this issue.
I had a related problem on my 801 which I purchased about 9 years ago (serial # 6). The left wing root rib had the wrong angle on the rear flange, resulting in about a 5 degree twist between #1 rib and the root rib. As I'd never built an airplane before, I didn't know that the rear spar should be straight--no twists and no bends--it's full length. I installed it as it was. When I built the right wing, the root rib was correct, which provoked me to ask ZAC about the first one. They insisted it was impossible that that root rib could have the wrong angle, as all those root ribs are made on the same form. (Don't get me started.) Bottom line: The rear spar should not bend or twist. Finally Roger said the simple fix is to cut off the offending flange and rivet onto the rib another piece of aluminum with a flange set to the correct angle--the angle that matches the other ribs.
To try to answer your specific questions:
1. The rear flange of the root rib is parallel to the rest of the ribs, and in the same plane.
2. My plane is 20 miles from here right now, but I seem to recall that the root rib rivets to the rear spar doubler, which would mean it is about 3mm shorter than the other ribs. Although when you build the cabin, you will be able to adjust the distance between the main and rear spar attach points slightly, you would be well advised to make sure your main and rear spars are EXACTLY the correct distance apart at the root end (look ahead in the instructions and find the template for setting the length of the top outboard tubes of the cabin frame--which determines how far apart the main and rear attach points will be) and EXACTLY the same on the left and right wings.
3. Further depending on my memory, it seems to me there was one row of rivets in the rear spar doubler outboard of where the root rib rivets to the spar. I will see my plane later today and will confirm or correct this statement this evening.
John Swartout
On Wed, Sep 17, 2008 at 10:54 PM, bcchurch <bcchurch(at)yahoo.com (bcchurch(at)yahoo.com)> wrote:
[quote]--> Zenith701801-List message posted by: "bcchurch" <bcchurch(at)yahoo.com (bcchurch(at)yahoo.com)>
I'm working on the right wing and ran into a problem with the root rib. When I locate the root rib, the rear spar deflects rearward 6 or 7 mm. The distance between the main spar and rear spar at all of the rear wing ribs is 820 mm. At the root rib, I get 827 mm. Now, the IB bottom skin is 820 mm wide which tells me that all the ribs are looking good except for the root rib.
I'm discussing the issue with Caleb but wanted to ask some of the 801 builders here a few questions:
1) is the root rib parallel to the other rear wing ribs?
2) is the root rib the same length as the other rear wing ribs?
3) does the root rib join the rear spar at the 1st or 2nd row of pre-drilled holes in the rear spar? (My pre-drilled skin tells me the first row in the rear spar is correct).
Without your parts in front of you, I realize it's a pretty small detail and probably hard to answer. I've attached an excel file with some measurements and notes to help describe my problem.
I suppose there are some that would say I'm nit-picking over a few mm. But, when I get that root rib in place I really see a curve in the rear spar between the root and station 1 and I just don't like that.
Thanks,
Ben
--------
Ben Church
CH801
Racine, WI
Read this topic online here:
[url=http://forums.matronics.com/viewtopic.php?p 4883#204883]http://forums.matronics.com/viewtopic.php?p 4883#204883[/url]
[quote][b]
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bcchurch
Joined: 10 Dec 2007
Posts: 25
Location: Racine, WI
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| Posted: Fri Sep 19, 2008 6:39 am Post subject: Re: 801 wing root rib |
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John, Thanks for the great reply.
I've re-measured my root ribs and main ribs from both left and right sides and all are the same length. Since the root rib attaches 1) to the inside of the rear spar doubler and 2) to the inside of the main spar extrusions, then I would say that the root rib needs to be shorter than the main ribs by the combined thickness of the rear doubler and the main spar extrusion. That combined thickness is about 6-7 mm which exactly corresponds to the deflection I see in the rear spar when I locate the root rib.
I'm thinking of cutting off the rear flange on the root rib and using a short piece of std L to join the root rib to the rear spar doubler. I will, naturally, call and ask Zenith about this. But, I would also appreciate comments / opinions from other builders. Please tell me if I'm doing something stupid.
On another note, what is the proper term for the thin sheet in the main spar that connects the top and bottom extrusions? I'm talking about the sheet with all the lightneing holes. I call it a "web" but I'm sure there's a better term.
Thanks,
Ben
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Ben Church
CH801
Racine, WI |
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jgswartout(at)gmail.com
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| Posted: Fri Sep 19, 2008 9:32 am Post subject: 801 wing root rib |
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I think "web" is the correct term.
Std. L is probably okay but I made a piece with a long enough flange mating up with the rib to put two rows of rivets into the rib, parallel to the rear spar.
I wouldn't be surprised if ZAC changed the shape of the root rib because it is so difficult to get a nice smooth curve in the root skin, and maybe made some the wrong length. I thought Roger told me once that they had actually changed the root rib to have a separate flange riveted on the rear end--but that was about 7 or 8 years ago so who knows? When I was fitting my root skins, I had to make a dummy out of .016 aluminum, trimming and fitting, trimming and fitting etc. ad nauseum, then duplicate it with .025. But even then, I chased a bubble 'round and 'round and 'round trying to get the skin to lay flat on the rear spar, the root rib, and the flange attached between #1 rib and the inboard end of the main top skin.
John
On Fri, Sep 19, 2008 at 10:39 AM, bcchurch <bcchurch(at)yahoo.com (bcchurch(at)yahoo.com)> wrote:
[quote]--> Zenith701801-List message posted by: "bcchurch" <bcchurch(at)yahoo.com (bcchurch(at)yahoo.com)>
John, Thanks for the great reply.
I've re-measured my root ribs and main ribs from both left and right sides and all are the same length. Since the root rib attaches 1) to the inside of the rear spar doubler and 2) to the inside of the main spar extrusions, then I would say that the root rib needs to be shorter than the main ribs by the combined thickness of the rear doubler and the main spar extrusion. That combined thickness is about 6-7 mm which exactly corresponds to the deflection I see in the rear spar when I locate the root rib.
I'm thinking of cutting off the rear flange on the root rib and using a short piece of std L to join the root rib to the rear spar doubler. I will, naturally, call and ask Zenith about this. But, I would also appreciate comments / opinions from other builders. Please tell me if I'm doing something stupid.
On another note, what is the proper term for the thin sheet in the main spar that connects the top and bottom extrusions? I'm talking about the sheet with all the lightneing holes. I call it a "web" but I'm sure there's a better term.
Thanks,
Ben
--------
Ben Church
CH801
Racine, WI
Read this topic online here:
[url=http://forums.matronics.com/viewtopic.php?p 5057#205057]http://forums.matronics.com/viewtopic.php?p 5057#205057[/url]
[quote][b]
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bobkat
Joined: 07 Sep 2008
Posts: 143
Location: Bismarck, ND
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| Posted: Fri Sep 19, 2008 10:12 am Post subject: 801 wing root rib |
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I agree John. I made mine twice on one side and three times on the other, neot including the carboard ones I also made. They are far from perfect, but I decided I'd live with them. I wish ZAC would have them moulded out of plastic to simplify making the darned things. The wing tips could be made from plastic, too. Would save a week or more of work, and after banging my head against the wall making them I'd gladly pay the difference!
[quote] ---
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Tom P
Joined: 19 Sep 2006
Posts: 15
Location: Beamsville, Ontario
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| Posted: Fri Sep 19, 2008 4:56 pm Post subject: Re: 801 wing root rib |
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Hi guys I just went out and looked at my completed wings and found that one was very straight at the root area but the other wing dips in at the rear spar at rib #1 only about a millimeter. I'm not worried about it but will be looking at the rest when I get things closed up. 6-7 millimeters would suck!
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Tom CH801
Dynon D180
Lycoming IO-360 From Teledyne Mattituck
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bcchurch
Joined: 10 Dec 2007
Posts: 25
Location: Racine, WI
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| Posted: Sat Sep 20, 2008 4:18 am Post subject: Re: 801 wing root rib |
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Thanks for taking the time to check your wings. So what would everyone recommend for a possible fix? Should I try and remake the entire root rib? Should I cut off the rear flange on the root rib and then rivet on a new flange so I can set the rib length? Other ideas?
- Ben
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Ben Church
CH801
Racine, WI |
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Tom P
Joined: 19 Sep 2006
Posts: 15
Location: Beamsville, Ontario
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| Posted: Sun Sep 21, 2008 1:27 pm Post subject: Re: 801 wing root rib |
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I would order the right length you need to make it the correct length. Keep in mind also that your cabin frame will be adjusted to the length of the main spar to the rear spar. When it comes time to do that you will be making a template for each wing that holds the top cabin frame at the correct distance for each wing. I'm not sure how much of a difference in the two would be acceptable so keep that in mind that you might want to make sure both wings will be kinda close in this distance. Mine happen to be exact! The final test though will be when I put the wings on, hopefully they fit perfectly and I made no mistakes while measuring for my templates.
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Dynon D180
Lycoming IO-360 From Teledyne Mattituck
http://home.cogeco.ca/~tomp |
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