Ribs: full length and aileron ribs

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Brian Amato
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Ribs: full length and aileron ribs

Post by Brian Amato » Mon Sep 03, 2018 2:51 pm

So, I've built about 12 or 13 ribs so far. Full length ones.
I keep pretending those extra gussets and aileron spars and stuff down there on the right end of the drawing are for later.
Well....now it's later and I need to ask this:
Do I just go ahead and build up all 18 ribs (I think the plans say 18) and then cut off the ones that become aileron ribs and add the extra stuff they require or....do I then build up special aileron ribs, using the same rib drawing but modify the rib jig to include the extra truss and gussets and area for the ail. spar?
How'd you guys do it?
Thanks in advance,
Brian

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taildrags
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Re: Ribs: full length and aileron ribs

Post by taildrags » Mon Sep 03, 2018 10:38 pm

Brian; I'm just a little bird sitting up here in the tree, watching the wing building as if I knew what I was doing. I didn't build the wings on my airplane, so I'm just going to speculate here. What I have seen on my airplane is that there are small variations in alignment between the wings and ailerons, some of it due to fabric tautening creating a slight twist or bow in the ailerons or what-not, with the wings not experiencing the same deviations due to them being larger. Looking at the plans, it seems to me that the best way to get the wings and ailerons to match up at the aileron cutout is to build all the ribs on the same jig and then leave the fabrication of the ailerons till such time as you can slide the ribs onto the spars on a table or jig and align them all. Once they are fixed in place, glue in the aileron spars and let everything cure, and then the trailing edges should be straight and square from root to tip. When that is all set up, the ailerons can then be cut out and hinges installed, but up until that point all the airfoil sections will be the same all the way down the wing since you built all the ribs the same, on the same jig, and squared everything up before installing the aileron spars and cutting them out. When you cut the ailerons out, nothing will move and the next challenge will just be tautening the fabric carefully so as to not introduce any twist or bow to the ailerons.

One variation of this process might be to build all the full ribs first, then add some spacers to the rib jig where the aileron spars go and build those last ribs with the hinge gaps ready to accept the aileron spars when the time comes. That seems like fussier work to me than building all the ribs the same though.

However, since I've never done it, this is all "just talking to talk", as they say in Texas.

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Tue Sep 04, 2018 7:39 am

Thanks for that input. Makes perfect sense.
The only other thought, tho, doing it the way you said is will everything line up properly building the aileron ribs kind of "in space" hanging out there.
Whereas if I build them right in the jig, I have to think they will be all alike and all lined up.
Who else can tell us what they did?
Brian

EAB4
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Re: Ribs: full length and aileron ribs

Post by EAB4 » Tue Sep 04, 2018 8:14 am

Hi Brian
The extra truss and gussets on the rib plan are actually for the 6 end ribs.
(2 on each end of the wing panels and 2 on the ends of the center section if you are building a 3 piece wing)

I made all of the regular ribs first, then modified the jig to make the end ribs.
Then, as Oscar said, when you are building the wings, you slide all the ribs onto the spars and get them into their final positions-
including attaching the trailing edges.
Then you add the extra supports and spars for the aileron hinges. When all of that is done, then you cut out the ailerons.

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Tue Sep 04, 2018 2:27 pm

Thanks for that input my friend. So good of you guys to come forward and share your knowledge with me.
Off to the shop to build more ribs :)
Brian

danoliver
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Re: Ribs: full length and aileron ribs

Post by danoliver » Tue Sep 04, 2018 8:06 pm

I just finished up builing my port wing and the very last thing I did, and I mean very last, was to cut loose the aileron. Fittings, cables, hinges, you name it, all set. Worked out good.

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Wed Nov 21, 2018 2:53 pm

OK....I thought I had this all sorted out in my noggin but now I have another question. Reading Piet stuff the other day....can't remember what site...the guy said you have to build all the ribs in the normal way, in the jig, with gussets...except the last 6 ribs. Leave the gussets off one side of three lefts and three rights (if you're building a 3 piece wing) because you're going to fully sheet the entire side of the rib, like one big gusset. Am I understanding that correctly?
Somebody jump in here.

EAB4
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Re: Ribs: full length and aileron ribs

Post by EAB4 » Thu Nov 22, 2018 3:09 pm

Brian, that's basically right but you only need to sheet 4 of the ribs-
the 2 outboard ribs of the center section and the butt ribs of each wing panel.
The sheeting keeps adds a place to attach the fabric on the butt ribs and
keeps the ribs from deforming from the tautening of the fabric.

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Sat Nov 24, 2018 6:24 am

Ah....gotcha !

danoliver
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Re: Ribs: full length and aileron ribs

Post by danoliver » Mon Nov 26, 2018 5:01 pm

I interpreted the 3 piece wing drawing to say that the fabric should be attached to the 2" wide plywood strips that conform around the rib and that the sides of the butt ribs were gusseted normally. I've never covered an airplane (this being my first build) but it seems like 2" of plywood should be a sufficient gluing surface. Also wouldn't you want the ends to be open to make it possible to connect the aileron cables and for inspections? I've seen it done both ways on Chris Tracy's site so I guess either works, I just wonder what's the advantage to sheeting the entire rib?

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Tue Nov 27, 2018 6:55 am

Also, don't I want to sheet the tail end of the main ribs, on the aileron side, to "box in" the area where the ailerons are going to live, as well as the tail end of the ribs that actually become the ailerons?

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taildrags
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Re: Ribs: full length and aileron ribs

Post by taildrags » Tue Nov 27, 2018 10:46 pm

Brian; based on how my Piet was built, I concur with what others are saying... only 4 of the ribs get fully sheeted and it's the ones that face each other in the wing attach fitting gaps if you're building a 3-piece wing. I guess if you're building the one-piece wing, none of the ribs get fully sheeted. The ribs out at the ends of the wings don't bear the full pull of the tautened wing covering fabric... the wingtip bow does, as much as anything.

At the wing attach fitting gap, my aileron control cables run through openings in the wing butt and centersection ribs to get to the pulleys and to make the crossover connection. I have a removable link (no turnbuckle) in the middle of my crossover connect cable for demounting the wings, accessible for inspection when I lift the center section flop panel.

As far as the ends of the ailerons and the inside faces of the aileron cutouts in the wings, I believe those just have fabric wrapped over them on my airplane... no wood closures. There isn't a lot of open space between the rib sticks at the tails of the ribs, so really no need for plywood closures there. I do, however, have just a tad of end-to-end twist in one of my ailerons from uneven fabric tautening and I can see how it takes a lot of patience, diligence, and trial fitting of the ailerons on the wings to make sure the trailing edges all flow smoothly before calling it good with the fabric tautening. Laying the covered aileron on a flat surface to make sure it's straight is fine, but you won't know if it flows into the trailing edges of the wing till you fit it in place... unless you're a real builder and not an amateur like me! Before I acquired 41CC and had to work on it, I had never worked with aircraft fabric covering materials or techniques before. I like fabric work, but then again that might just be the Poly-Brush fumes talking ;o)

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Wed Nov 28, 2018 9:27 am

Thanks so much for the reply !
The great thing about the internet and the photos you can find out there, is, you can see about 4 different ways guys have approached the same problem. Not all the same...not one right one but not wrong either.
I tend to get obsessive about stuff and I have to reel myself back in and remember what we're doing here: making a 70mph little wood airplane from 1929 plans. In the end, it will fly just great and be a whole bunch of fun.
Bear with me guys...you'll probably see me tossing out questions for the next two years about how did you do this and that. Then it will be my turn to help.
Brian

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Sun Dec 02, 2018 10:45 am

Another aileron question (at the risk of driving you guys nuts):
If you look at the plans, specifically drawing#5 that shows the ribs, wings and ailerons, it shows that ailerons are nothing more than conventional full length ribs with the addition of "spruce aileron beams", braces and a strap hinge; only meant to be cut free of the wing once everything is all assembled and lines up. Makes perfect sense. Except the inside most rib of an aileron is NOT a cut rib...it's its own "shorty" rib and, as the plans say "filled with solid webs". So...do we just make a couple shorty ribs in the rib jig to come up with those guys? I would think so.
But, then, what's the space between the end of the aileron and the first full rib? It doesn't show a dimension on the plans. Just use our best judgement? Is there a hard number somewhere I'm over looking? Am I putting too fine a point on all this?
What did you guys do here? I see lots of pics on the internet but no two alike

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Terry Hand
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Re: Ribs: full length and aileron ribs

Post by Terry Hand » Mon Dec 03, 2018 7:20 am

I am not yet flying, but that is essentially what I did. I sacrificed the aft end of two extra ribs I had made, and made what you call a "shorty rib." Seems to have worked.
Semper Fi,

Terry Hand
Athens GA

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Mon Dec 03, 2018 8:29 am

Thanks so much Terry

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taildrags
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Re: Ribs: full length and aileron ribs

Post by taildrags » Mon Dec 03, 2018 10:30 am

Brian; I'll look in the plans to see if there is anything said about the gap to leave between the aileron and the wing, and maybe also look through some of the other plans in the Flying & Glider manuals to see if any of those give a clue. However, as a starting point, when cutting out your ailerons with a conventional circular saw or jig saw with fine teeth, or even a Japanese pull saw, you're not going to get much finer a kerf than about 3/32"-1/8" and that's probably just fine. You don't want the gaps too narrow so the control surface doesn't bind when the wing deflects under G load such as in a steep turn.

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taildrags
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Re: Ribs: full length and aileron ribs

Post by taildrags » Mon Dec 03, 2018 10:22 pm

Brian; I looked at Drawing No. 5 again, and also surveyed a number of different airplane designs in the '30, '31, 32, and '33 Flying & Glider manuals just to compare things. Regarding the hinge gap between the aileron and wing, Drawing No. 5 of the '34 Hoopman plans shows it to be 3/8" at the top wing surface, but I suspect that that distance was the minimum that was practical to construct using "barn door" strap hinges. That gap can be made a little tighter by using piano hinges, but just for comparison, the hinge gap on the '30 Alco Sportplane is called out as 3/4", the '30 Northrop Glider calls for 1", the '32 Ramsey Flying Bathtub calls for a whopping 1-1/8" gap (but it employs an oddball tubular hinge with straps that bolt to the spars and requires more gap space), the '33 Henderson Longster and Gere Sport both call for 1", and our closest match is the '31 Georgias Special and the '33 Pietenpol Sky Scout at 1/2" . There's your ballpark for the hinge gap.

For the end gap between the aileron end rib and wing rib, the '30 Alco Sportplane, '31 Georgias Special, '32 Ramsey Flying Bathtub, and the '33 Gere Sport, Longster, and Sky Scout all call for 1/2" and only the '30 Northrop Glider -the only unpowered wood-wing design that I looked at- calls for a tight 1/4" gap. There's your ballpark for the end gap. Note that the dimensions given are for wood-to-wood, and you'll need to allow for the thicknesses of fabric covering and reinforcing tapes on both surfaces that face each other, so don't cut the gaps down too tight now!

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Tue Dec 04, 2018 8:12 am

Thanks Taildrags. I didn't make myself clear.
It wasn't the hinge gap I was looking for...that's called out on the plans. I meant the end gap between the aileron and the wing rib and I think you're right:
I think 1/2" AFTER fabric would be fine. Not enough to allow too much wind whistling thru there but enough so there is no binding if something flexes.
Coming right along here. Going up to the shop in a minute and route out for the rudder to vertical stab hinges. I've got a neat little router base I use in my guitar making for inlaying pearl and abalone. Vernier adjustment and very stable. Fits any version of a Dremel tool. IF it works out as slick as I think it's going to, I'll take pics and pass it along to the forum.
Wish me luck :)

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taildrags
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Re: Ribs: full length and aileron ribs

Post by taildrags » Tue Dec 04, 2018 10:36 pm

Brian; I'm not going to wish you much luck because in woodworking, luck doesn't seem to go as far as sharp tools do ;o) Interesting that you make guitars. The fellow who lives next door to my office is a professional chef, but in his spare time he's a luthier who makes violins and violas. Like anyone who works in wood, when my neighbor sees a piece of wood he's looking at a whole lot of different things that are hidden inside it. His hands and tools, and yours, will bring out more than just objects and shapes though... they will bring out music!

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Wed Dec 05, 2018 6:45 am

A lovely way to put it. And I agree.
Guitar making is the only project making hobby I have that, after its done, it doesn't just look pretty or hang on the wall or, what ever: it sings !

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Thu Dec 06, 2018 10:28 am

Well...I was going to post some photos of how slick my little dremel router base (that I use for routing the cavities for pearl and abalone in guitar work) worked out for me. I used it to make very precise routes for Oscar's lovely cast aluminum hinges but.......the forum won't let me post photos without some sort of permission, I guess.
Suffice to say, it worked great. I would seriously suggest any of you interested take a look at this ad:
https://www.youtube.com/watch?v=6vRh6dLn7eM

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Thu Dec 06, 2018 3:05 pm

This is the neat little router attachment on my Dremel tool.
Attachments
P1015858.JPG

Brian Amato
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Re: Ribs: full length and aileron ribs

Post by Brian Amato » Thu Dec 06, 2018 3:09 pm

Guess I figured out how to attach photos to a posting.
I'll try to attach two more.
This is how I did a very tidy job of routing for the hinges we can buy from Oscar:
The extra pieces of wood clamped to either side of the wood to be routed are there to provide extra bearing surface for the sole of the router. Worked slick!
Attachments
P1015863.JPG
P1015862.JPG

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