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Author: Subject: The tubing to use in an old Dural AU4G design
FlyBoyBC




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[*] posted on 11-20-2017 at 06:49 PM
The tubing to use in an old Dural AU4G design


Hello! I am working with the following design:

http://home.caiway.nl/~fnijhuis/zeki.../sb_buggy.html

It uses Kee Klamp railing fittings and Dural AU4G tubing in the following dimensions:

5 m tube 35 x 31 mm (chassis, frame, front fork) 1.38in
0,60 m tube 35 x 25 mm (central frame tube)
0,50 m tube 30 x 26 mm (used for reinforcements)

Dural is an obsolete trade name described as an aluminum and copper alloy used in aerospace because of its high resistance to stress and its lower density than steel .As a result of various evolutions of the designations and standards, it was then called AU4G (Standard NF A 02-104), and from now on 2017 (Standard NF A02-004 / EN 573-1)

From this I gather that 2017 Alu/alloy tubing of the above dimensions should be exactly equivalent to the original but when I search for 2017 tubing it seems like it basically does not exist. I can only find 2017 in rods and wire.

I looked at 6061 T6 seamless tubing and can only source 1.375 X 0.058 locally which is thinner than the 35 x 31 mm called out in the old plans but I don't know if this is even a valid comparison.

All I really need to know is what tubing material can I find that is between 1.31in and 1.38in that has similar mechanical properties to "Dural" in the above sizes? I hope for the corrosion resistance of 6061 T6.

I would certainly consider using 1.375″ OD x 0.049″ WALL x 1.277″ ID Seamless Stainless Steel 316 Round Tube and


1.375″ OD x 0.065″ WALL x 1.245″ ID Seamless Stainless Steel 316 Round Tube as I can source it locally.

As you can tell I know nothing about the subject. I can WORK with metals and I do nice work but this old standard has got me stumped.

A little help?
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indigo_wolf


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[*] posted on 11-20-2017 at 08:09 PM


The link you provided for the buggy was abbreviated and got broken in the process. It took me a while to expand and correct the link to:

http://home.caiway.nl/~fnijhuis/zekitez/buggy/sb_buggy.html

Ironically I was just looking at this buggy on Popeye's website earlier this morning (waaaaay earlier).

OK, let's see if we can suss out a bit more about your question.

<* Insert appropriate sound effects here *>



ATB,
Sam




"I never had any friends later on like the ones I had when I was 12 - Jesus, does anyone?" - The Body by Stephen King
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indigo_wolf


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[*] posted on 11-20-2017 at 08:45 PM


I think your next stop might be

Maryland Metrics. The site touts itself as:
"The One-Stop Source For Metric And British Sized Fasteners, Wrenches, Cutting, & Measuring Tools, Metal Shapes..."

https://mdmetric.com/tech/alumcomp.htm

Unfortunately their website is a bit of a throwback to the 1970s-80s and is a bit of a PITA to navigate.

You might have better luck calling their 800 number in the morning.



Given them a holler, if they aren't a direct solution,

Apparently 2017 is now 2017a and it carries a different name under:

ISO - Al-Cu4Mg
Canada - 17S
France: A-U4G
Germany ( DIN 1700) - AlCuMg1
Germany ( DIN 17007) - 3.1325
Great Britain - H14
Italy - P-AlCu4MgMn
Japan - A2017

ATB,
Sam




"I never had any friends later on like the ones I had when I was 12 - Jesus, does anyone?" - The Body by Stephen King
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FlyBoyBC




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[*] posted on 11-20-2017 at 09:05 PM


All I really need to know is what tubing material can I find that is between 1.31in and 1.38in that has similar mechanical properties to "Dural" in the above sizes? I hope for the corrosion resistance of 6061 T6.


Basically "what is used instead of Dural tubing now"?
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FlyBoyBC




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[*] posted on 11-22-2017 at 05:15 AM


After some intense reading and comparing and thinking about it I have tentatively concluded that 6061 T6 seamless tubing with a slightly thicker wall may be equal to this old "dural" standard but I have not finished my analysis yet.

I have found it very difficult to find any information on "dural" and this "AU4G" standard.

I have also been thinking about trying fairly thick CF tubing 53mm dia by 3 to 5 mm thickness. The torsional load transferred to the frame from the swanseneck is held by a bolt going through the entire joint. I am not sure how well this would work with CF.

For $100 I can get a 1 meter long piece of 35mm x 25mm CF on ebay. That is exactly the length of the axle of the "Slow Brain".

Do you suppose CF tubing epoxied into the Kee Klamps would work? I have seen railing systems put together in exactly this way but would it be as strong as this Dural stuff? Most information seems to indicate that it would be vastly superior but I have never seen anybody build anything bigger than a quadcopter using CF tubing. No go-carts or minibikes made from CF tube out there despite the glowing statements that it's twice as strong as aluminum of the same dimensions. People chop bike frames apart and replace the straight sections with CF tube and use the original bike parts to join the tubes together. This is fairly similar to what I am proposing. It works for bikes......

If I just blindly believe that then I should be able to clamp and glue 35x25 and 35x29 CF tubing using Kee Klamps and end up with something stronger and lighter than the original.

I would hate to spend all that money and time only to discover it is too brittle or something...........
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FlyBoyBC




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[*] posted on 11-22-2017 at 06:14 PM


I found a table at Aircraft Spruce:

http://www.aircraftspruce.com/catalog/mepages/aluminfo.php

It shows that "17S" is an OLD standard and 2017s would be the modern term. In our case it's actually 2017A

Can anybody help me contrast and compare 2017a with Dural AU4G and THICK (5mm) 3K CF "roll wrapped" tubing? I have NOT been able to find 2017 tubing anywhere it is available in rods and wire.
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FlyBoyBC




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[*] posted on 11-22-2017 at 06:16 PM


Actually the REAL question is could I use 6016 T6 or CF and if so how thick should the walls be?
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FlyBoyBC




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[*] posted on 11-22-2017 at 06:19 PM


THIS page : http://www.dexcraft.com/articles/carbon-fiber-composites/alu...

seems to indicate that CF tubing of the SAME dimensions would be vastly superior in all ways to what they laughingly refer to as "aluminum"......They do not say what kind....anywhere.....it's ridiculous. Serious page with great information about an unidentified material.

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jimbocz




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[*] posted on 11-23-2017 at 01:52 AM



I admire you for trying to build something interesting, but I'm a bit nervous about that buggy actually working as you'd like. Did you choose that design just because it doesn't require welding? What are you going to do about a seat? I'm concerned that the seat arrangement in the picture is going to be a bit loose and will make it difficult to deal with the side pull common when buggying.

If you want a cheap buggy, why not buy something used? By the time you have sorted out a decent seat and wheels, you will have spent as much on a home build as a decent used buggy.

If you are really keen on building one yourself, I can understand that, but there's better designs out there. The plans for a Parasorm Typhoon are on the web and that's a well proven design that's been in commercial production for a while. You may even be able to adapt it to a no weld solution .
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FlyBoyBC




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[*] posted on 12-3-2017 at 05:55 PM


Thank you for your input jimbocz.

I appreciate your concern but I do not share those concerns. I am actually building a PPG trike a lot like the "Trikebuggy Bullet" which uses the Trikebuggy as it's base. I find that the only negatives to this design are slightly higher weight and cost due to the Kee Klamps and the downtube to main frame crossmember assembly applies a ferocious amount of torque to the main frame tube. I have already worked out an easy solution to the latter issue and since my trike will be built primarily from aluminum rather than steel it will probably weigh LESS than a Trikebuggy (or Parastorm Typhoon) of the same dimensions.

No I did not select this method so I would not have to weld, I selected it because I need to be able to break my unit down for transport and storage and because I believe with careful material selection and assembly of the Kee Klamps this could be a superior building method. The Kee Klamp system, if it is properly implemented is as strong a connection as welding. It is safety rated at 2000 lbs pullout force with a safety factor of 200% meaning the ultimate failure is at 4000lbs! The tubes will stay connected under conditions where a weld would fail. As it is not being used in its intended manner care needs to be taken to make sure tolerances are closer than Kee would state and high torque or critical connections can be drilled through and pinned with a bolt rather than just clamped (as is shown in the plans) and epoxy can be used in some of the highest stressed connections just to make it that much more secure. I don't believe I will need epoxy but all of the important connections will be pinned.

As for the seat I agree totally. I do not plan to make the "Slow Brain" my redesign (tentative name "Quick Wit" ;) ) will have a redesigned front end to reduce that torque on the main frame tube and I will not just be jamming the hub nut into the axle and hoping that friction alone will hold it there (welded/epoxied). Mine will be bigger and beefier and will use more than one material for all of the tubing. The forks, downtube and main cross member will all be 2024 T3. The axle will be stainless steel and the lesser stressed parts will be good ol' 6061 T6 to save on cost.

The Parastorm Typhoon is a great design but would end up a LOT heavier than what I envision if converted to Kee Klamp assembly. It would be overkill. PPG trikes can be a lot less beefy than kite buggies in that they have to withstand the same kinds of stresses but only for a few seconds at at time. It will see considerably less wear and tear per session/season than it would if used for kiting on the ground.

As for the actual issue brought up in the OP. "Dural" became known as AU4G then 2017 then 2017a which they still make but it is not available in tubing or pipe. So although 2017a IS the appropriate replacement material for "Dural", AU4G, 2017 and 2017a if you need to use tubing then 2042 T3 is the appropriate choice and tubes of appropriate dimensions are available.

Bear in mind that as long as the original builder is not a bald faced liar he put 800 bumpy km's on his Slow Brain and never had to do anything to it. Not even re-tighten a clamp.

The Slow Brain is not a perfect design but it can be the basis for a superior trike if redesigned and assembled carefully. For my purposes the Slow brain could be made as designed and drawn and it would work but I am going to improve the design and make it more appropriate for a flying machine.
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jimbocz




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[*] posted on 12-4-2017 at 02:12 AM


Fair enough Flyboy, I hope it works and makes a good buggy for you. Just FYI, The parastorm typhoon was made out of aluminum and was pretty light for a buggy of that size. I've never seen a buggy that didn't break down by removing the front fork and usually the rear axle and wheels as well. Once you've done that, even the biggest buggy is manageable to put in a car. There's always a trade off between the advantages of breaking your buggy down into smaller pieces and the general PITA of spending a bunch of time taking the thing apart and putting it back together before and after you fly .

I've ridden on the beaches in Northern France that the guy was talking about, it's one of my all time favourite beaches. We rented a cottage just down the road from the beach so I didn't have to drive, and each day I could go out for a few hours of buggying. The beach is about 6 miles long and sections of it are designated as clothing optional!

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FlyBoyBC




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[*] posted on 12-4-2017 at 02:44 PM


Hello Jimbo, I am trying to do my due diligence as thoroughly as possible and I am trying to be as creative as I can. For example when you assemble Kee Klamp normally you cut the tubes flat, stick them in the connector and tighten. My plan is to fishmouth the tubing in the same way you would when welding. That will allow a bit more tube to fit into the klamp and the solid contact between tubes will help to stabilize the joint. As I said before high torque or flight critical connections will be pinned by AN bolts and castle nuts that are either safety wired or at least cotter pinned. If I have the slightest fear that the connection is still not stable enough I can also use epoxy. I doubt I will need epoxy.

I was not aware the Typhoon is aluminum but my point still stands. That design would be heavier and overkill for my application....As I said I am not making a Slow Brain I am just using it's construction method. I may end up with a configuration that is closer to some other design but I kind of doubt it. Aside from that downtube to crossmember torsion that I spoke about this is an ideal format. Simple layout that gives you the correct geometry. It's so much like a Trikebuggy.

I want to be able to break the trike down a little farther than removing the wheels forks and axles for off season storage. Besides that this design and method means repairs will be cheap and easy. (like a Skybolt).

Kite Buggy on a nude beach in France......Yah there are some good reasons for getting into this activity! LOL.

I posted here originally to ask about Dural AU4G, 2017a and what the modern version of this material is called. I answered my own question in the post above so this is the last entry here.

THE MATERIAL TO USE IN BUILDING THE SLOW BRAIN IS: 2042 T3 at least for the forks, downtube, main cross member and axle (I would do the axle in stainless). I also suggest welding or using epoxy to hold the wheel nut in the axle rather than just relying on a friction fit.

If anybody would like to follow construction of my buggy and paramotor frame go to http://groups.yahoo.com/group/ppghomebuilt/ and search the term "Quick Wit".

I have just started and have other airplanes in the hangar that I can not ignore so this may take a while.
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jy1zoom


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[*] posted on 4-12-2018 at 03:35 PM


Any updates?
Have you tried Metals Supermarket? they have one here in Richmond BC.
www.metalsupermarkets.com
Prices for tubing is reasonable. Theres a leftovers bin of shorter pieces at reduced prices.
Have you find a local source of tube fittings?




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