Corben Jr ace build.

[Tench745]

Hi all, I'm a first time builder embarking on my first project, a plans-built Corben Jr Ace. I will have a lot of questions as I progress which I intend to post in this thread. Hopefully people will have some answers that they're willing to trade for progress updates. First question is about built up ribs.
The Jr ace has ribs built from 1/4" x 1/4" capstrips with 1/16" ply gussets. I'm assembling with T-88 and aircraft nails. I'm curious how much of an issue there is with the nails splitting the intercostals?

[cdlwingnut]

My ultra-piet project used 1/4 by 1/4 capstrip for ribs, I used t-88 and then used staples instead of nails, no splitting problems. If you decide to change to staples put a toothpick under them to make it easier to pull them when the t-88 is cured.

[martymayes]

Trick you can use if you encounter splitting is run the point of the nail over a grinding wheel. The dull point will crush the wood fiber when it's driven vs. separating the fibers which causes splitting.

[Tench745]

Martymayes, is the intent to just round the tip, or flatten it completely?
Followup question, if the intercostals do split under the gussets should they be replaced or is the gusset holding the two halves together still sufficiently structural? (Basically, I mussed up, how do I fix it?)

[martymayes]

Martymayes, is the intent to just round the tip, or flatten it completely?

You want to disrupt the point's wedge shape because that is what splits the wood, just like using a wedge to split firewood.

[Frank Giger]

Hurray!

Please, lots of pictures and descriptions of your build!

I did it, and it was invaluable - folks saw some mistakes I was making and corrected them, and gave advice on better ways of doing things.

But make sure you show your worst work, not just your best. That's where one needs the help, after all.

[Tench745]

Y'all want progress, then I guess I'll start in.
I began by having a copy of the plans made at Staples. I think it cost around $120. The overview plates fit in a 2'x3' poster frame and hang on my wall for quick reference.
6806

I guess now is as good a time as any to fess up that I've already built 12 of 26 ribs. I'm averaging about 2.5 hours per rib.
I made some choices when laying out my ribs to speed production. I cut all my intercostals square rather than beveling each one on a sander when it goes into the jig. This lets me work in my living room and not run back downstairs to the garage every time I need a new piece. Similarly, I chose to notch the plywood nose blocks rather than beveling the upper and lower capstrips to meet it. I feel like there's more gluing area this way and it means I can just put a capstrip straight into the jig.
6807

All the nose blocks and gussets were rough cut on the band saw, placed in a jig, and finished with a router. The leading edge notches on the nose blocks were cut in another jig on the table saw.
6810


The first rib was laid up in the jig, and each piece used to set up a stop block on my table saw's crosscut sled. The second piece was cut, tested in the jig, and if it fit the remaining 24 pieces would be cut. Each piece gets it's own cup, numbered per the drawings.
6808
6809

[Tench745]

Here's a shot of one of my worst splits.
6812
If this type of split doesn't make the rib unairworthy, I will be filling the ones I have with epoxy for added strength. Opinions?

[martymayes]

Here's a shot of one of my worst splits.
6812
If this type of split doesn't make the rib unairworthy, I will be filling the ones I have with epoxy for added strength. Opinions?

yup



The only purpose of the nail is to clamp the gusset in place until the epoxy dries. Theoretically, can remove the nail after the glue is dry and a lot of builders use staples so they can do exactly that.





should have the wings ready to cover by next weekend?

[Frank Giger]

Very, very cool.

For those of us who never worked in wood, when assembling one of the ribs, could you take pics in a step-by-step manner?

[Tench745]

How I build a rib:
Nose block, and preformed upper and lower capstrips are placed in the jig. Both capstrips are left long at the trailing edge, the lower sits atop the upper for now. Intercostals are added, forcing the capstrips into final shape. The upper capstrip is marked where it abuts the lower. It's then removed from the jig, trimmed with a razor saw and sanded to final fit. Then all the joints are hit with a sanding bar to bring the pieces down to the same thicknesses, there is some slight variation between them. A vacuum with a brush attachment pulls up all the sanding dust before gluing begins.
Here are all the parts in the jig post sanding.
Cardstock spacers are used either side of the spar blocks to allow easier installation of the finished rib on the spars.

6821

Next, the nose gusset is laid in place with an aircraft nail partly driven into the upper and lower capstrips to act as a locator pin and to remind me which side gets epoxy. (I've already finished smearing epoxy on two nose gussets only to realize I did wrong side)
6822

I then trace out my nose block template onto the gusset to help me see where to nail.
6823

I then lay out all the remaining gussets around the rib in the appropriate pattern for the rib I am making. Some ribs have large gussets at the trailing edge, and the ribs that will get compression struts don't have two of the upper gussets. Laying them out now gives me a chance to catch a mistake before everything is covered in glue.
6824

Back side of the nose gusset smeared with epoxy. I started off using acid brushes to spread the epoxy, but felt like more glue was being used to fill the bristles than was actually getting on the parts, so now I just spread it around with the popsicle stick I mixed the epoxy with.
6825

Here I've switched from the nose gusset to one of the smaller gussets because it's easier to fit in frame. The steps are the same for all of them.
I smear a little epoxy down into the joint I'm working. Then set the gusset, epoxy-slathered side down, on top of it.
6826

I drive a few nails to hold it while I glue and set the rest of the gussets. These suckers are tiny, so they need to be held with tiny pliers or a hemostat when starting them.
6827

Then I come back in and finish nailing the gussets down, as per the nailing pattern from the plans.
6828

The nose gusset and trailing edge gusset get nails all the way around their perimeters, again, as per the plans.
6829

The rib is then removed from the jig so the process can be repeated on the other side.
6830

[martymayes]

looks good - are those brass nails?

[Frank Giger]

Fantastic! Thank you so much!

Everything looks very neat and tidy. I was expecting "EPOXY THIS SIDE" scrawled in pencil on the parts, though; I guess you're a lot brighter than I am.

I was a bit surprised to see that the diagonal ribs pieces are square on the ends and the triangle formed filled with epoxy. I'd of thought they'd be pointed to fit into the joint. I suppose it really doesn't matter, as they're gusseted, and epoxy is strong stuff.

One of the many reasons I'm excited to see your build. All I know is aluminum tubing, gussets, and pop rivets.

[Floatsflyer]

I was a bit surprised to see that the diagonal ribs pieces are square on the ends and the triangle formed filled with epoxy. I'd of thought they'd be pointed to fit into the joint. I suppose it really doesn't matter, as they're gusseted, and epoxy is strong stuff.

Ya, me too. Caveat: I know nothing. So can someone with aeronautical structural engineering weigh in here regarding this methods ability to carry the same load as one with diagonal angled joints without failing.

[martymayes]

This is heartily debated around the internet; cutting the capstrip with square ends vs mitered ends. The overwhelming consensus is that the gusset plate carries the load so there is no difference in strength between the two methods. There have been numerous test both scientific and backyard to confirm that hypothesis.

[Frank Giger]

That's kind of what I was thinking - that and the fact that the epoxy is pretty strong stuff, forming a solid plug at the joint.

Besides, if the stresses on the aircraft are so strong that the joints on the ribs are breaking it is probably the least of the concerns at that point.

And now we've given Tench something to worry about that he doesn't need to! Well done, my EAA brothers, well done.

[martymayes]

The Tony Bingelis method is clean the excess epoxy from the joint. Adds weight and no strength. Otherwise, Tench745's ribs follow standard practice and in no time he'll have a complete set.

[Tench745]

The Tony Bingelis method is clean the excess epoxy from the joint. Adds weight and no strength. Otherwise, Tench745's ribs follow standard practice and in no time he'll have a complete set.

Yep, I read a bunch of Tony's stuff before starting on this. I'm coating the joints with epoxy, but not entirely filling them. It makes me feel like I'm adding strength even if I'm not. The backs of the gussets are left epoxy coated so I don't have to get in there with a brush later to varnish it.

Frank, I would like to point out that I don't actually know anything about building an airplane either. I am a theatrical carpenter so I know something about wood, and something about welding, but I'm teaching myself and learning as I go from manuals, books, videos, and all the great materials from the EAA. I read everything I could get my hands on for about six months before admitting to myself I had to build an airplane.
Soon I'll join the local chapter, 486, and start learning everything I can there too. This past summer they were rebuilding an unairworthy Sonex from scratch and the building bug bit me hard.

Also, only the leading and trailing edge gussets are orientation specific; all the others are (thankfully) reversible.;)

[Jeff Point]

Looks good so far.

One thing to remember- the plywood gussets have a light coat of varnish on them, so they should be lightly sanded on the epoxy side to achieve a stronger glue joint. This is a debated topic for sure, but you could make a few test pieces and pull them apart to see for yourself if it is worth it.

pro tip- easier to sand the large sheet before cutting into gussets.

[Tench745]

Looks good so far.

One thing to remember- the plywood gussets have a light coat of varnish on them, so they should be lightly sanded on the epoxy side to achieve a stronger glue joint. This is a debated topic for sure, but you could make a few test pieces and pull them apart to see for yourself if it is worth it.

pro tip- easier to sand the large sheet before cutting into gussets.

Known and done. All plywood gussets were sanded on both sides, some of them even before they were cut. There are 602 of the 1.25"x.75" gussets. I sanded them before cutting. Almost all of the rest I had to do after.

[engine]

Trench745 Would you be able to copy your plans for the Corben baby ace as I cant seem to get a set. Tried that guy in Georiga no luck. I will glady pay you for them. I have been a certified aircraft mech for over forty years.Might able to give you some tips on your project. Thanks Monty.

[engine]

Tench 745 I am wondering if you got my email I am looking for a set of plans for a Corben baby ace called the guy in Georiga no luck Could you copy yours and sell me a set. Would be much appericated. Thanks Monty.

[Tench745]

I had the opportunity to visit Bill Wood in Toccoa, GA a month or so ago. He responded to my email about it pretty quickly. Perhaps give that a try first: aceair@windstream.net
I know he still sells the plans, so I would feel guilty selling you a copy of mine.
There was recently someone on the Corben Aircraft group on Facebook who had a set for sale as well, they may still be available. https://www.facebook.com/groups/320195594809744/

[engine]

Trench745. I tried to contact Mr Bill Wood twice by phone and a email. I cant get a reply from him. His email will not work for me. Do you know any place else where I could buy these drawings. As I want to get building this aircraft. This is the phone no I was trying 706-886-6341 and the mail was the one I got from you. Thanks Monty.

[Tench745]

That's pretty much all the contact info I have for you short of mailing them something via snail-mail. If you've only tried contacting them recently, they may be away for the holidays, but I don't know for sure. I actually bought a set of plans from an individual who wasn't able to use them and started building a Zenith instead.

[Tench745]

Questions for those who know more than I do:
1) I'm looking at phenolic pulleys for the control cables; are bearings worth spending nearly twice the price of the bushing variety?
2) I'm also trying to find parts to assemble the wing's drag wire clevises. These are bent up from strap steel with a nipple, square washer, and lock nut.
The plans show it as below.
I figure I can make the bent metal strap, the square washers should be easy if I can't find them premade somewhere, but the threaded nipple is giving me fits. I've found similar parts from a J-3, but they're around $9 apiece and I need 24 of them just for the wings. Is there a simpler/better/cheaper/newer way of doing these fittings?
6874

[ulpilot]

http://www.buchananspokes.com

Motorcycle wheel spoke nipples.

[Tench745]

Well, I've ordered the next load of materials. Motorcycle spoke nipples are coming for the drag wires.
I have an order into Aircraft Spruce I'll be picking up when I visit my family in SC for a belated Christmas. The spar stock won't be ready in time, but the steel for wing fittings and plywood to finish the butt ribs will come home with me.

The rib jig was modified to make the aileron ribs. I'm building the ailerons in as part of the full ribs so that I can cut the ailerons out as one piece once the wing is assembled.

In the picture below are, from top to bottom: a standard rib, an aileron rib, and one of the aileron endcaps. Everything forward of the plywood on the endcap will be cut away once I have the ailerons assembled. Better to be too long than too short right now.
6882

I started only gluing up one side of the ribs at a time to make it seem like I was making progress faster and keep motivated. The added benefit of this is I'm now done with my rib jig which can be modified for the butt ribs while I go back through finishing up the un-gusseted sides. I have to finish gusseting the back sides of three more ribs; then it's time to build the butt ribs.

[Tench745]

So, project updates! I finished building all the ribs over the winter, and ran out of things I could easily do in my living room until the garage warms up. Once spring finally started springing, about a week ago, I started in on wing hardware.
7151
7152
I got the aileron cable pulley bracket cut and bent, as well as the aileron control horns. Unfortunately, when bending the control horns the corners of the bend began to crack. Only then did I realize I laid the fittings out with the 4130 sheet's grain running along the bend instead of across it. I intend to remake these parts with the grain running the other way, but will have to buy more steel to do so. The plans do not say which way to align the grain, but do say to weld these corners after bending. I wonder now if the designer's intention was to lay them out the way I did and counteract this kind of cracking with the welds. Any comments on these fittings or anything else is welcomed.
7153
7154
7155

[martymayes]

1. Make sure the bend radius is not too small for the thickness of the metal. That will cause cracking.

2. Layout the part so the bend will be properly oriented to the grain of the metal; you want to bend across the grain to minimize cracking;

3. Put a radius in that corner before bending. When laying out the part, drill a hole in that corner so there will be a radius instead of a sharp corner.

[conodeuce]

It's great to see another tube-n-rag project moving along, at the same stage as mine (Acey Deucy). Where'd you go for spar material? I used Edensaw in Port Townsend, WA. But, because of growth defects in one board, I'll be ordering a main spar board from another source. Perhaps Aircraft Spruce.

[Tench745]

It's great to see another tube-n-rag project moving along, at the same stage as mine (Acey Deucy). Where'd you go for spar material? I used Edensaw in Port Townsend, WA. But, because of growth defects in one board, I'll be ordering a main spar board from another source. Perhaps Aircraft Spruce.

I ordered from Aircraft Spruce since I had family I would be visiting down by their GA location. Unfortunately, I couldn't pick it up when I visited and had to have the order shipped anyway. It took them months to get the stock in because "the pieces you needed were very large." Plans call for a solid 3/4" x 5 11/32" front spar almost 13' long. I quickly looked over the stock and it all looks quite beautiful. I'll be going over it with a fine toothed comb when I get closer to using it.

[conodeuce]

I ordered from Aircraft Spruce since I had family I would be visiting down by their GA location. Unfortunately, I couldn't pick it up when I visited and had to have the order shipped anyway. It took them months to get the stock in because "the pieces you needed were very large." Plans call for a solid 3/4" x 5 11/32" front spar almost 13' long. I quickly looked over the stock and it all looks quite beautiful. I'll be going over it with a fine toothed comb when I get closer to using it.

After waiting several months for drying, it was very disappointing to begin planing one of my expensive spar boards only to have severe checking revealed in places that prevented it's use as a main spar. That board, once any other imperfections are identified and discarded, will become aileron spars, as well as cap strips, etc. Fortunately, one board was in excellent condition. So, I have one wing's worth of ribs mounted. Moving on to metal component acquisition and fabrication now. (And looking for a larger shop.)

[Tench745]

I'm slowly fabricating and acquiring fittings and hardware to start assembling the wings. Right now I'm stuck on finding drag/anti-drag wires for the wings. The plans call for 9/64" SAE1050 steel rod in 51" lengths. I have absolutely no idea where to find this. I assume that there are other suitable alloys, but I don't know enough to choose one. I'm trying to keep this project as low-cost as I can while still doing things right. It occurs to me that I should just start contacting local metal suppliers as I'll need steel tubing eventually too, but thought I should get the opinions of those who know better than me first.
Any advice would be helpful.

[Sam Buchanan]

I'm slowly fabricating and acquiring fittings and hardware to start assembling the wings. Right now I'm stuck on finding drag/anti-drag wires for the wings. The plans call for 9/64" SAE1050 steel rod in 51" lengths. I have absolutely no idea where to find this. I assume that there are other suitable alloys, but I don't know enough to choose one. I'm trying to keep this project as low-cost as I can while still doing things right. It occurs to me that I should just start contacting local metal suppliers as I'll need steel tubing eventually too, but thought I should get the opinions of those who know better than me first.
Any advice would be helpful.

Many aircraft with similar wings use 1/8" cable with turnbuckles for drag/anti-drag bracing. The turnbuckles involve some expense but this is an easy method to rig.

My D.VII replica uses an even simpler method. The cables are installed without turnbuckles--tension is achieved by pulling the cables tight with a ratchet strap as the nicopress sleeves are swaged. Here are photos of the cables in assembly:

7303

7304

7305

http://fokkerd7.com/wing-top.html (http://home.hiwaay.net/~sbuc/fokkerd7/wing-top.html)
It doesn't get any simpler and less expensive than that! :)

[conodeuce]

... The plans call for 9/64" SAE1050 steel rod in 51" lengths ...
My airplane uses a similar type rod. I will be ordering from Aircraft Spruce. Your part's 9/64" (0.141) dimension suggests the AN part would be AN-701 (0.138 diameter and 6-40 threads).
In my plane's case, the next size up is specified (AN-703 having diameter of 0.190).

http://www.aircraftspruce.com/catalog/appages/tierods.php

[conodeuce]

@Sam: I'm curious what is the trammeling procedure for your wing?

Thanks.

[Sam Buchanan]

@Sam: I'm curious what is the trammeling procedure for your wing?

Thanks.

Uh....even after Googling "trammeling procedure" I'm still not sure what it means....please enlighten me. :)

[martymayes]

Uh....even after Googling "trammeling procedure" I'm still not sure what it means....please enlighten me. :)

It's just a method of making sure the wing bays are square by measuring corner to opposite corner.

[conodeuce]

@Sam: About trammeling ... I like to follow Marty Feehan's progress on his Sportsman 2+2 via his web log. Here is his trammeling entry from 2010:

http://www.marty2plus2.com/past-posts-and-pictures-by/may-7-2010.html

Also: http://gobinkley.com/hostedpictures/How-to-Trammel-a-wing.pdf

(And, "holy cow", I hadn't come across the goblinkley.com site before my googling a moment ago. Check out the the main site. I'd give my left __ for a Warner 145).

[rwanttaja]

Uh....even after Googling "trammeling procedure" I'm still not sure what it means....please enlighten me. :)
This document describes the process for Fly Babies... see starting on Page 24:

http://www.bowersflybaby.com/PB100/Guide_2.pdf

Ron Wanttaja

[conodeuce]

Ron, that's an incredibly useful manual. At a glance, it is obvious that it is very relevant to many of us building other models. Thank you.

[rwanttaja]

Ron, that's an incredibly useful manual. At a glance, it is obvious that it is very relevant to many of us building other models. Thank you.

Pete Bowers' 100th birthday was last month. The complete "How to Build a Fly Baby" magazine series (14 parts) was published in Sport Aviation in 1963-1964, and can be downloaded for free by any EAA member.

In honor of Pete's centennial, the Fly Baby community is assembling a series of "Companion Guides" for those who might want to build a Fly Baby from the original EAA articles. Full details on the "PB100" Web page:

http://www.bowersflybaby.com/PB100/index.html

Not only will folks find the companion guides for the "Building a Fly Baby" series, but there are some workmanship and shop setup guides as well.

Ron Wanttaja

[Sam Buchanan]

Ok...I just wasn't familiar with the "trammeling" term even though I've used that technique on all sorts of projects over the years. I learned something today. ;)

However, the processes y'all have been linking to are way more technical that what I used on the D.VII wings. The key to laying out the wings is a drywall square and some wood blocks. Here you can see the edge of the build table being used as a reference to draw perpendicular lines on the table with the drywall square.

7306

Once reference lines have been drawn for the spars and compression struts, wood blocks are attached to the table to hold everything square.

7307

The blocks immobilize the spars and compression struts as the drag/anti-drag cables are installed.

7309

No "trammeling" per se was necessary to build a square wing. Quick, simple, and square. I realize this may not be "complicated" enough for some builders. ;)

7308

I used the same technique on the wood Legal Eagle wings (and Super Koala and MiniMax) with the same "square" results. Here are the D.VII wings chasing a sunset this evening:

7310

[conodeuce]

Sam, I wonder if the importance of wing trammeling is a matter of wing length? How long are the wings on the Fokker D.VII and the Legal Eagle?

[conodeuce]

@Ron: I hope you are planning to go to this year's Concrete Vintage Fly-In. If so, would you mind letting me know which day? I would like very much to see a Fly Baby in person.

https://concrete-wa.com/fly-in/

Thanks

[Sam Buchanan]

Sam, I wonder if the importance of wing trammeling is a matter of wing length? How long are the wings on the Fokker D.VII and the Legal Eagle?



No, the only purpose of trammeling is to get the wing structure square/straight. As long as you end up with a "square" wing (ribs and compression struts perpendicular to the spars and spar ends properly aligned) the particular squaring technique doesn't matter.

Here is one of my Legal Eagle wings (should look familiar to anyone who has built any of the light, wood aircraft:

7311

[martymayes]

I wonder if the importance of wing trammeling is a matter of wing length?

If the wing bays are not square you could end up with some forward or aft wing sweep which would certainly be exacerbated on longer wings.

[conodeuce]

If the wing bays are not square you could end up with some forward or aft wing sweep which would certainly be exacerbated on longer wings.

I didn't phrase my "wonder if" question well. My question: Is it possible that shorter wings are naturally more rigid, and so might not require extra measures for ensuring squareness? But, from the looks of Sam's Legal Eagle wing (which looks pretty long to my eyes), it seems that his excellent vertical jig and careful craftsmanship resulted in a very square wing, without the final step of trammeling.

[conodeuce]

A side question about wing rigidity: How often do drag-anti-drag rods require tightening? Over time, do things loosen up? Do big temperature changes have an impact? I had a rag-wing Cessna 140 for several years. I don't recall maintenance log entries indicating that sort of work.

Thanks.

[rwanttaja]

A side question about wing rigidity: How often do drag-anti-drag rods require tightening? Over time, do things loosen up? Do big temperature changes have an impact? I had a rag-wing Cessna 140 for several years. I don't recall maintenance log entries indicating that sort of work.
I don't think it happens that often.

With THAT said, I found a loose internal brace on my Fly Baby a couple of months back. The wing had inspection panels that "kinda" gave me access to the turnbuckles, and I managed to snug it back up again.

It loosened, and I was concerned that I had a nicopress slipping or other dire event. But I re-tightened it and did a better job of safety-wiring (used brass wire instead of stainless for better ability to wrap tight in a limited area). Checked it several times since then, and it's been holding.

I discussed the issue on a previous thread:

http://eaaforums.org/showthread.php?7948-Alternate-Turnbuckle-Safetying-Techniques

Temperature-wise, I have noted one instance where hot temperatures resulted in control interference. Don't think it was due to the internal bracing, though, probably the wood.

http://www.bowersflybaby.com/tech/heat_controls.html

Ron Wanttaja

[rwanttaja]

@Ron: I hope you are planning to go to this year's Concrete Vintage Fly-In. If so, would you mind letting me know which day? I would like very much to see a Fly Baby in person.
Probably not Concrete, but I should be at the Arlington Fly-In a week prior. Probably on Saturday.

Ron Wanttaja

[Tench745]

I'm liking the dialogue. I already have some fittings built for the drag wires. What are some other ways people are fabricating them? I like the stock setup as it requires no turnbuckles.

[conodeuce]

Ron, I'm sure I'll spot you at Arlington. You'll be the only non-RV there. :-) (Not to rag on RV's. If I have a second airplane in me, and any money left, I'd love to build a spiffy RV-4).

[conodeuce]

I'm liking the dialogue. I already have some fittings built for the drag wires. What are some other ways people are fabricating them? I like the stock setup as it requires no turnbuckles.
Your airplane's approach is pretty common. On my airplane, drag-anti-drag rods connect to the ends of a simple bent metal piece:

http://zoemertech.com/753-compression-strut_details_small.jpg

I'm actually working on those now.

[martymayes]

Ok...I just wasn't familiar with the "trammeling" term even though I've used that technique on all sorts of projects over the years.

It really should be called "squaring the wing bays" instead of using the tool name (trammel points) as a verb (trammeling) because the same task can be accomplished without using trammel points as you have cleverly figured out.

[martymayes]

A side question about wing rigidity: How often do drag-anti-drag rods require tightening? Over time, do things loosen up? Do big temperature changes have an impact? I had a rag-wing Cessna 140 for several years. I don't recall maintenance log entries indicating that sort of work.

After installing they require little to no maintenance. It's a routine inspection item during an annual to ascertain they are still taut and doing their job. If they are loose, it usually means the wing has incurred some kind of damage.

On a side note, you may have noticed the drag/anti-drag wires in your C-140 were different sizes. The ones in the bay near the wing root are much larger dia than the ones in the outboard wing bay as the drag/anti-drag loads lessen from root to tip. Also, if you were to replace the fabric on your 140 wings with aluminum skin, the drag/anti-drag wires would no longer be needed. The aluminum skin would suffice for those loads. Neat stuff.

[Tench745]

Build updates on my blog. https://aviationcomingeventually.blogspot.com/2018/07/more-fittings-and-hardware-delivery.html

[conodeuce]

Build updates on my blog. https://aviationcomingeventually.blogspot.com/2018/07/more-fittings-and-hardware-delivery.html
Are you enjoying the metal working aspect of the project? I'm at the same stage; after a couple of sessions I'm beginning to develop a little confidence in my technique. The rib building was so pleasant that, when progressing to fabricating 0.090 steel parts, I really felt like a total noob. And, alas, I am.

[Tench745]

I've done a fair bit of metal fabrication working in theatre, but nothing that requires the kind of finishing that aircraft parts require.
I always have to psych myself to deal with the noise and mess of working steel, but once I get going it's easy to lose myself for a few hours. It can be therapeutic to get lost in the work. I too feel in over my head occasionally (like every time I pick up a welding torch to practice).

[Tench745]

After much scouring of the inter-webs I have come across information suggesting that cold rolled 316, 416T, and possibly cold rolled 304 stainless rod should have the same tensile strength as 1050 steel. I'm thinking I will upsize from 9/64ths to 3/16ths as it's easier to find and forgo the spoke nipples for doubled nuts. Anyone see any potential problems with this?

[Tench745]

So, as I progress through my build I come across another question: Zinc Phosphate, or Epoxy primer on steel wing fittings?
The point is moot as I've ordered the epoxy primer already, but I'm curious to know how the two stack up against one another in an unexposed area like inside a wing.

[Sam Buchanan]

So, as I progress through my build I come across another question: Zinc Phosphate, or Epoxy primer on steel wing fittings?
The point is moot as I've ordered the epoxy primer already, but I'm curious to know how the two stack up against one another in an unexposed area like inside a wing.

Epoxy primer is an excellent moisture barrier.

[Tench745]

Looking for input on attaching wooden truss ribs to spars. The Corben plans call for the ribs to be glued and nailed through the verticals into the face of the spars. Most other homebuilts I see use triangle blocks to capture the rib. My first question is, what does a proper rib installation look like using this method; I'm having a hard time finding reference pictures.

My remaining questions requires a little explanation.
On the suggestion of another builder, when assembling my ribs I held the vertical members of the rib back from the spar openings a few thou to allow them to slide onto the spars easier. When I actually got the spar stock it measured a few thou shy of 3/4" and it looks to me like way too much space now.
So, what I would like to know is, how much space between the spar and rib is "ok" as long as my compression struts are a snug fit. Do I need to glue in shims at the ribs to take up the space? Can these gaps be filled with T-88 and if so will I need a thickening agent?
Basically, I think I done mussed up. Just to put it out there, I do have a tech counselor I'll be talking to at the next chapter meeting, but I like to ask here first.

[conodeuce]

Lots of wings attach the ribs via glue + nailing through the vertical member. That's true of the Acey Deucy, and, I believe, Paul Poberezny's Baby Ace, and the Pietenpol, for example.

Just in case it sheds a little more light on the subject, here are the instructions for the Acey Deucy: http://zoemertech.com/ad/acey_deucy_building_info.pdf

As for the loose tolerance between rib opening and spar, gluing a shim would be one approach, depending on just how big a gap you have.

[Tench745]

I'm still not clear on the process of epoxying a rib to the spar. Like, the physical process of applying epoxy under the rib before nailing. Some pictures would be helpful if anyone has them.

A side thought, I'm thinking about using a set of letter stamps to stamp part numbers into my steel parts so I don't get them mixed up after painting. Any reason not to? Would a stamped number/letter be a potential stress riser or anything?

[Tench745]

Another question for the hive mind. Anyone tried brushing on ep-420 epoxy primer? How does it compare to spraying?

[martymayes]

Another question for the hive mind. Anyone tried brushing on ep-420 epoxy primer? How does it compare to spraying?

A foam roller will give the second best results to spraying. There is some technique involved, you'll figure it out quick.

[Tench745]

Thanks for the replies, guys. This is where things stand right now. I test-fit the ribs on the port wing and all looks good. Had to put things away to get my garage back for a bit. I need to thread drag-wires and finish the drag wire fittings, then all hardware needs epoxy primer before final installation. Unfortunately, it's 18° outside so painting is a no-go for a while. I can also cut the aileron spars to size and mill down some spruce for various wing bracing, but that's about it for now. Practice my welding and chase down parts for the next steps.
77417742