This document describes the process for Fly Babies... see starting on Page 24:
http://www.bowersflybaby.com/PB100/Guide_2.pdf
Ron Wanttaja
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This document describes the process for Fly Babies... see starting on Page 24:
http://www.bowersflybaby.com/PB100/Guide_2.pdf
Ron Wanttaja
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
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.
Attachment 7306
Once reference lines have been drawn for the spars and compression struts, wood blocks are attached to the table to hold everything square.
Attachment 7307
The blocks immobilize the spars and compression struts as the drag/anti-drag cables are installed.
Attachment 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. ;)
Attachment 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:
Attachment 7310
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?
@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
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:
Attachment 7311
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.
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.
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?...ing-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
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.
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).
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-compressio...ails_small.jpg
I'm actually working on those now.
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.
Build updates on my blog. https://aviationcomingeventually.blo...-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.
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).
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?
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.
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.
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.
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?
Another question for the hive mind. Anyone tried brushing on ep-420 epoxy primer? How does it compare to spraying?
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.
Attachment 7741Attachment 7742