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Author Topic: Bending/forming Alclad wings  (Read 1582 times)

Offline Peter Lott

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Bending/forming Alclad wings
« on: January 22, 2022, 10:48:45 AM »
Greetings all,

Does anyone please have instructions or advice on the bending of Alclad wings? As in the 0.010" Alclad type on the various Pink Lady plans and many others. There may have been an article in the Speed Times (by Partner) at some stage, but I do not have it.

Thank you in anticipation ;)
Peter

Offline Mark wood

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Re: Bending/forming Alclad wings
« Reply #1 on: January 22, 2022, 11:42:13 AM »
Greetings all,

Does anyone please have instructions or advice on the bending of Alclad wings? As in the 0.010" Alclad type on the various Pink Lady plans and many others. There may have been an article in the Speed Times (by Partner) at some stage, but I do not have it.

Thank you in anticipation ;)
Peter

I don't have the plans for the Pink lady but I am an A&P and can give you guidance on what you need to do to maintain the integrity of the bend. go to the FAA.gov website and get the AC43.13. Inside of that you can find the minimum bend radius for you material. From that you can use your break or make a forming tool with the correct bend radius to form your skins. Many people make a form for this using a couple wood blocks and a pushing tool to form the LE. A forming tool wouldn't be a hard tool to create. A handy break can be made using a couple pieces of angle and some hinges in about an hours worth of effort. Maybe two hours and the tool will be with you forever.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline Dave Hull

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Re: Bending/forming Alclad wings
« Reply #2 on: January 22, 2022, 07:26:19 PM »
Peter,

There was a practical article a few years back on one of the speed forums. I copied that and perhaps added bits and pieces of my own thoughts. Let me see what the best way to post it here might be....

Something I might mention in case sheet aluminum nomenclature is new to you is that Alclad refers to alloy sheet using base metal that is not as corrosion resistant as pure aluminum, so a very thin cladding of pure aluminum is added to the outside of the rolled sheet. It helps get closer to the best strength and better corrosion resistance. What it also implies is that you are looking for alloy-grade wing skins. This is not always used. For example, a number of the local guys have been using aluminum roof flashing for years. This is not alloyed as far as anyone can tell. Yes it is softer, but it bends much easier, to a smaller nose radius without cracking, and is more workable for guys working in their garage without the benefit of a sheet metal shop.

Dave
« Last Edit: January 22, 2022, 07:48:30 PM by Dave Hull »

Offline Dave Hull

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Re: Bending/forming Alclad wings
« Reply #3 on: January 22, 2022, 07:38:36 PM »
Here is one previous response:

Building Aluminum Wings
From the clspeed bulletin board
5/07

Hi, Andrew....

Most in the USA who build their own alum. wings find the mat'l at local hardwares.  It is "flashing" mat'l, used for laying in the troughs created when two house roof angles meet to make it waterproof.  It comes in small rolls of varying widths.  Few buy the whole large sheets that metal warehouses sell because it is so unwieldy, especially to bring home.

These days, the alum flashing has a thin plastic coating that must be sanded off to get to the metal for bonding the trailing edge.  You can't polish the alum to a shiny gloss because of this coating, so the finish has to be as it comes.

There have been past articles on how to make these wings in SpeedTimes. I use "Pliobond" for bonding mine.  It is a rubbery contact cement you brush on and allow to partially dry before closing the joint.  I bake it at 250 F for 6 hours to cure. Some use epoxy, and some use the glue they use to rebond rear view mirrors to car windshields. 

I make a long fixture from 1" X 1/8" angle alum with tightening screws ever 2 inches to hold the TE together while the glue cures.....

Dave Williams

Offline Dave Hull

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Re: Bending/forming Alclad wings
« Reply #4 on: January 22, 2022, 07:59:41 PM »
Here was one method being used by John Newton and Fred Anderson, documented by Fred several years ago, again, on the speed forum:

I got some [aluminum] last week for $12US at Ace Hardware in Southern California and went to John Newton’s and we made two nice "D" wings. This is a new brand product, 12"x10' rolled and taped into a 4"x12" tube and shrink wrapped... [It is] .0092" thick and a little harder than other brands. It bends and works well.

The label reads:
     Aluminum Flashing
     12"x10" ECON made in U.S.A.
     #68-312
     Amerimax Home Products
     Lancaster, PA 17603
     barcode# 49821 68312

John Newton is using a Locktite glue these days that squeezes out and is then catalyzed with an aerosol spray. Let me know if you need the product code.

The process is kind of like making your first burrito...The first one is real messy and a little crooked and you have to clean yourself up afterward; but it feels good when you are done...

General Procedure:
1. Get (2) 2"X4"x4' alum blocks and screw folding flat lengthwise with a 4' piano hinge
2. Cut the aluminum skin blank oversize about an inch on the TE planform
3. Open the huge blocks, place flush lengthwise to the front edge on top of your bench
4. Place your blank on top w/ proposed leading edge radius over hinge line
5. Put a 48"x2-3" x 1/8" thick steel rule on top
6. Locate its inner edge line 1/16" back of proposed LE radius
7. Clamp one block side, skin and steel rule to the bench with multiple C clamps

Do not rush the following process......
8. Bend up other block 120 degrees on first bend
9. Check the radius on LE now, then bend a little more
10. Unclamp the rule if you have to and move back steel rule, repeat gently…. Repeat gently, bending smoothly. Repeat gently, check that radius.... In order to achieve a smooth radius, you will find a way, leave it a little large at first

Finally, you will have a taco shell wing when you squeeze the trailing edges together. The leading edge radius now should be what you want when you finish. The wing will appear way [too] thick in section, like a Piper Cub, but do not flatten it yet....
11. Turn the clamp bars around and put the overcut trailing edge flash between the bars
12. Clamp the bars gently at first and press the taco into the clamp a little at a time.
13. Measure your overall chord now and massage the wing to its final dimensions. Do not ever tighten the clamps at all until you first sight down the leading edge. The leading edge will for sure, always, have some sort of bow in it, be careful here.
14. Straighten the leading edge, you can add tip wash-in here if you like, which is cool
15. Clamp it all tight, check it again real good. Get a carpet knife or utility blade (the grey kind with the blades that snap off new). Slice the aluminum flush with the blocks for your "Fresh New Trailing Edge" look. Open the blocks, throw away the scrap. [Then] clamp the "new taco" TE back in 1/4" and check for straightness.
16. Get a sharp felt tip and mark each skin surface where it touches the blocks.
17. Take it apart and then practice putting to the marks straight and clamping fluidly.
18. Take it apart again and practice clamping it straight again.
19. Practice again, it’s got to go together smooth and fast.
20. Open up the TE and sand the inside of the blank where the spar and TE glue is going. Take a walk, come back and put on some gloves and a mask
21. Apply your weird, probably toxic, glue in a controlled bead on both sides
22. Take a deep breath and assemble the whole mess and clamp it
23. Take a last look at the LE, but be quick
24. Take the catalyst and spray it down the inside of the wing
25. Make sure it's all straight, but it's too late to fix now...
26. Go to your nearest Mexican Food Cafe for 8 hours and celebrate.

Remember, the skin is still kinda plump looking? If you want to put in a spar, all you have to do is glue both sides and stick it in, then press it between boards.

The biggest problem I have had is saying 'Bueno' to a senorita at the cafe, and when I got home two days later the blocks were stuck for good...waddamesss....


Offline Dave Hull

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Re: Bending/forming Alclad wings
« Reply #5 on: January 22, 2022, 08:06:44 PM »
Perhaps a few follow-up comments?

1. Both guys acknowledged that you need to cut a bevel on the clamping bar in order to be able to bring the top folded material down far enough to make a completed bend. The bevel goes next to the bend, on top.

2. Various different adhesives have been used. The old school method was pliobond. More recently, I think guys prefer an epoxy. I have bonded this aluminum using JB Weld with no issues so far.

3. You can set a 1/16" solid rivet in the corners, if your wingtips take a beating. If the joint doesn't start cracking at the tip it won't progress, either....

4. If you use a sheet metal brake, you need to understand setback. Calculate a value based on your material alloy, thickness and then adjust the brake. Otherwise it is simply "mangle by trial and error...."

5. I have found the flashing material holds up pretty well on a "mature" Sport .21 model I have.

6. The flashing material I have been using for various projects does not have the "plastic coating" that the original post mentioned, and I know I bought it well after the speed forum thread appeared. So look around for the material that you prefer.

Offline Peter Lott

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Re: Bending/forming Alclad wings
« Reply #6 on: January 23, 2022, 09:48:43 PM »
Thanks to Mark and Dave for the valuable advice!

Some background- I live in Cape Town, South Africa... I went to some trouble obtaining a sheet of 0.010" 2024 T3 Alclad through the supplier (who happens to be 1000 miles away from me in Johannesburg) who imported it from the USA. 0.010" is almost unknown here, the more common ones of 0.016", 0.020", 0.025"being readily available. It came in a container with a large shipment. I chose Alclad I guess, because my background is also aircraft maintenance of 40 years experience, although the past 30 years have been with the regulator (the local equivalent of the FAA). A fellow C/L friend actually used some Venetian blind material to make up a speed wing: Thin "commercial" Al sheet is not at all common below about 0.020" here (but I am working on it ;)). If I can get around the cracking of the leading edge, which I think/hope I can, I'll use the Aircraft Spruce catalog specifications for 1/64" 2024T3 that give a bend radius of 1-1/2t-3t. (I do have a hard copy of AC 43-13 .1B from years ago but it doesn't give data for 0.010".)

Offline Mark wood

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Re: Bending/forming Alclad wings
« Reply #7 on: January 23, 2022, 10:17:19 PM »
Thanks to Mark and Dave for the valuable advice!

Some background- I live in Cape Town, South Africa... I went to some trouble obtaining a sheet of 0.010" 2024 T3 Alclad through the supplier (who happens to be 1000 miles away from me in Johannesburg) who imported it from the USA. 0.010" is almost unknown here, the more common ones of 0.016", 0.020", 0.025"being readily available. It came in a container with a large shipment. I chose Alclad I guess, because my background is also aircraft maintenance of 40 years experience, although the past 30 years have been with the regulator (the local equivalent of the FAA). A fellow C/L friend actually used some Venetian blind material to make up a speed wing: Thin "commercial" Al sheet is not at all common below about 0.020" here (but I am working on it ;)). If I can get around the cracking of the leading edge, which I think/hope I can, I'll use the Aircraft Spruce catalog specifications for 1/64" 2024T3 that give a bend radius of 1-1/2t-3t. (I do have a hard copy of AC 43-13 .1B from years ago but it doesn't give data for 0.010".)

I think you could readily use the BR for 1/64 for your estimation. The 2024T3 is pretty tough and I'd give a couple samples a try with 2t BR to see how it stresses. Depending on how you make your bending tool you can form the nose for that radius fairly easily. The minimum BR 1-1/2t is likely going to work fine as well.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline Dave Hull

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Re: Bending/forming Alclad wings
« Reply #8 on: January 24, 2022, 03:29:17 AM »
Peter,

Sounds like you are just about there.

Even in Southern California, finding .010 sheet is difficult. Most places will stock .016, but that's a big weight penalty for model parts.

I forgot to mention that if you have a choice doing the layout work on the piece of material that you purchased, you can successfully bend a slightly tighter radius if the bend is oriented across the grain of the sheet. The grain is the rolled direction. If your piece has the mill marks on it (labels calling out the specs and alloy) these will be printed along the grain.

Another comment is that if you only have a small piece of stock, which in my case might be a cutoff obtained from a metals distributor "scrap bin," the 6061 materials are marked with red ink and the 2024 materials are marked with blue. I assume this is generally true, not just in the USA. It can help keep track of things at times, but watch out if you have a lot of different materials around.

Wishing you success with your project!

Dave

Offline Peter Lott

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Re: Bending/forming Alclad wings
« Reply #9 on: March 06, 2022, 08:14:55 AM »
Update on the project...

I had a bunch of wings for a couple of fellow speed flyers as well as myself, water jet cut last week. Very nice edges! Now to sort out the 2"X4"x4' aluminium blocks or similar, then onto the bending process.

Thanks again for all your valuable advice ;)
Peter

Offline Motorman

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Re: Bending/forming Alclad wings
« Reply #10 on: March 06, 2022, 08:50:49 AM »
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« Last Edit: March 06, 2022, 09:41:01 AM by Motorman »

Offline Motorman

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Re: Bending/forming Alclad wings
« Reply #11 on: March 06, 2022, 08:53:38 AM »
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« Last Edit: March 06, 2022, 09:40:45 AM by Motorman »

Offline pmackenzie

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Re: Bending/forming Alclad wings
« Reply #12 on: March 07, 2022, 04:47:53 AM »
I have never done a wing leading edge, but if you are getting cracking try getting the part a bit warm before bending.
The part in the video was splitting, just getting it warm was enough to prevent it.
No idea of the grade of aluminum, China's best of some sort.

MAAC 8177


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