Aluminum Tube & Gusset Airbike / Legal Eagle / Parasol Thread

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addicted2climbing

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So I'm not sold on this concept. I think I could cut, cope and weld a 4130 structure faster than I could program, drill and pop a aluminum copy. I'm pretty sure my 4130 example would be lighter, cheaper and far more robust than the proposed.

Aside from the slight "inconvenience" of learning to weld, where is the advantage for a one off design? Or are we following the same fantasy where we are all going to become kit "manufacturers" and revitalize the industry with single place, 65 mph aircraft?

What is the context here - an airplane or production of kits? And what is the "design to" philosophy - cost, schedule, or quality?
I think VB is looking to speed up the process to make many at a time to offer a kit... For that its likely faster than the 4130 method but as you said for a one off just weld it..
 

litespeed

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If you guys could think about a square tubing Airbike/Ranger built with a world wide available 6060 alloy, this would be great.
Great idea, Not all the world is the USA and the rest of us pay a fortune for aircraft grade alloys. So if it can be a version that uses a commonly available one that would mean a lot more around the world could be built and lowers the cost further.

Since were not after big speed and not needing a 254lb limit, a slightly heavier but cheap tubing and skins/gussets could be made. Then it becomes a truly buildable design for even undeveloped areas, just do it from printed plans.
 

bifft

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I was just thinking of starting a thread to ask about a specific part of tube and gusset construction, but I'll put it here. My idea is about the diagonal tubes in the truss. Might it be possible to use two sheet metal straps in a X instead of one diagonal tube? Rivit to the gusset. They would have no strength in compression, just in tension but would be quite a bit lighter than the diagonal tube.

You would need to be careful to have the straps tight when you install them or it wouldn't take any load until the frame had already significantly deflected. My thought on that was to have the strap a bit long with a 1/4" hole in it that you would put a bolt/pin in to pull it tight as you drill the rivit holes. You then cut that part off before riviting.

It would be similar to the very early (191x era) wooden frames with wire bracing in concept. I've never seen any tube and gusset that did the diagonals in the truss this way, but might it work?
 

Toobuilder

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You don't do any of the programing, you download it. And this thread really isn't about your 4130 welding skills, it's about aluminum tube and gusset parasols.
The first post invites criticism, and I see some issues.

I'll generally agree that the tube and gusset approach can be applied to the airbike type. That said, this approach will probably result in a heavier, weaker, and more expensive structure compared to welded steel. On top of that, the engineering, programming, setup and run and fabrication of unit #1 of the T&G will also take longer than the welded steel counterpart. I'd opine that welding equipment and skill development is equitable with CNC routers and programming, so where is the advantage for construction of a single example?

Now, if you intend to produce many kits for public consumption, one might overlook the engineering inelegance of the T&G. However, one also has to consider the same CNC magic can be applied to 4130 tube. Cut to length tubes with perfect fishmouthed ends, numbered and ready to install. That changes things considerably in my book.
 

Victor Bravo

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My experience around airplanes, and hanging around several people who were much smarter than me, has taught me that there's a reasoin and a use for every common aircraft building method and material. Welding works great for the people who are set up to weld. Wood works great for the people who have those tools and like working with wood. Same with sheet metal, plastic, etc.

For a certain demographic or target population builder, I think AL tube and gusset is attractive. Whether that demographic population is tens of thousands of people, or two dozen... I'm not sure. But it would be a much smaller bet than investing in huge molds for a plastic airplane, or huge jigs for a steel tube airplane.

And yes, to clarify the original intent of this thread, my thoughts were leaning toward solving the equation for either a commercially mfg. kit, or a "thumb drive" airplane construction, or something else that involved far more than a single example. If I was only wanting to make one prototype airplane, the time and effort to have it built in CAD - and then machine the kit - and then actually build the airplane... would be a lot more time.
 
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cheapracer

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My experience around airplanes, and hanging around several people who were much smarter than me, has taught me that there's a reasoin and a use for every common aircraft building method and material. Welding works great for the people who are set up to weld. Wood works great for the people who have those tools and like working with wood. Same with sheet metal, plastic, etc.
EXACTLY.

I am bitterly disappointed that after 40 years of trying, I am absolutely useless at welding, worse when you see someone take it up and in 40 days they weld like a Pro, I've seen it. I don't really understand wood, nor have confidence in it.

But I am very good wih metal otherwise, and very good with fiberglass (non-structural)

To each his own, and we can only tell people the advantages to us as we understand them and have developed and setup our workshops around them, not tell others they are wrong for using their specific skillsets.
 

Aerowerx

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....For a certain demographic or target population builder, I think AL tube and gusset is attractive. Whether that demographic population is tens of thousands of people, or two dozen... I'm not sure. But it would be a much smaller bet than investing in huge molds for a plastic airplane, or huge jigs for a steel tube airplane.....
IMHO there are a lot more people out there that are willing to learn how to pop a rivet than learning to weld.
 

Victor Bravo

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To quote Lt. Columbo, ... just one more thing...

Part of this exercise is also addressing the different skills and attention spans of today's "new school" mentality. Homebuilders and home craftsmen and car mechanics.

In the days of the original Volksplane, it was envisioned an easy quick build for the average Popular Mechanics reader of the day. That may or ay not have been actually true but the VP was within the imagination and "I could do that" range of the average Joe of the day.

Today, the average Popular Mechanics reader probably does not have a couple of gas welding bottles laying against the garage wall. Today's "average Joe" probably doesn't have a table saw or a router either. But even more importantly, I am afraid that this guy doesn't look at a VP as being within the "I can go get a table saw and a welding torch... and then I can do that" range.

I'm guessing (hoping) that he would look at a pop rivet gun airplane project and say "Well, at least that I can do". YES there have been 12 million RV's built, which require more skill than what we're talking about, but I still think that the RV is not an "entry level" project. And he just went to pop rivets recently anyway :)
 

Toobuilder

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So this thread kind of jumped the shark... If this thread is indeed a "...how to become an effective kit manufacturing business...", then I'd suggest defining the market and price point before settling on a manufacturing process. T&G might very well be the most effective solution but, as my chief engineer used to say, "without data, it's just whining".
 

proppastie

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Im just daydreaming, a Cloudster style fuselage with tube and fabric wings and tail.

What do you think?
what does it weigh? is it strong enough? lots of ideas here but there is lots more to do than toss around concepts......TLAR is not a reasonable way to design a structure.
 

Victor Bravo

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So this thread kind of jumped the shark... If this thread is indeed a "...how to become an effective kit manufacturing business...", then I'd suggest defining the market and price point before settling on a manufacturing process. T&G might very well be the most effective solution but, as my chief engineer used to say, "without data, it's just whining".
Watch out for that shark, Fonzie! :) If I'm drifting my own thread off into oblivion, it's not intentional. The original purpose was to split off and continue a discussion on whether and why the T & G method is worth pursuing for small low performance homebuilts, on the basis of cost and ease of assembly.

The references to kits and manufacturing (from me) were to address specific sub-topics.

Back to the original focus... I do think that this method of construction is appropriate fo consider despite small losses in efficiency or elegance. I'll leave it to Toobuilder to quantify the loss in efficiency or weight gain, but I do believe the loss is acceptable in cases where the aircraft design is prioritizing faster assembly and/or lower required skill set for the builder.
 

ScaleBirdsScott

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T&G might very well be the most effective solution but, as my chief engineer used to say, "without data, it's just whining".
That's the thing, this is the proper engineer sort of thinking, going back to first principles and such. It's a valid approach when someone says "I have an idea for a mission, what's the best way to accomplish it?"

I see this concept as somewhat borne and respondent to market/design thinking, not engineering methods. What is optimal doesn't matter as much as what is most practical. The starting point literally is "I like the idea of plane X, but I don't want to use method Y to get it, and there seems to be a method Z I'm much more interested in using and which I bet others would like to use too. How can we get close to the original result X but using method Z?"

And then you can start to apply some design and engineering finesse to solve that specific problem. But we're not going back to first principals here with a clean slate to re-invent the high-wing single-seat runabouty sort of mini cub/kitfox/etc. We already know we want one of those warts and all. Seems a few of us have pretty-clear end goals in mind from a design perspective with easily contained engineering problems to solve in the process. Someone has to just start sketching or something.

Another way to look at it is "I want one of those Legal Eagles, but I already have this CNC machine and a pile of 6061 and rivets, oh no"
 

ScaleBirdsScott

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Of course the Cloudster built in aluminium tubing and gussets.
Honestly with how minimal that box is, I wonder if you'd be better off with just an aluminum sheet box with L-angles in the corners. You'd have to really model up both and do some comparisons; but I am pretty sure that a few flat strips of pre-drilled .025 riveted to some L-angle longerons, while using a lot more rivets, will save time and weight if you're trying to make a simple box boom. That could easily transition to a tube+gusset cage up front.
 

TFF

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Where building like this really takes its hit is not engineering, it’s value of finished aircraft. Wood is considered more a forever material than the pop rivet and tube plane. One of the hits today on ultra lights is “can I get what I put in back.” I drive my truck and it looses value every mile. Buy an airplane and i better get what I payed out. That is what goes on. Someone building in this manner has to be willing to accept it might be worth scrap after the fun. It should not be that way, but that is how it is viewed. That really hits on someone wanting to go this way. Less skill but less value for the effort. Less chance to sell it when ready. Like I said it probably should not be this way but it is. That makes the market smaller than skill level.
 

Toobuilder

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I think the catch 22 here is that the T&G method is attractive/viable to the novice builder only AFTER the kit manufacturer has invested heavily. If an end user has a short assembly period, that means the manufacturer has taken on that burden - and unless the manufacturer is benevolent, that burden transfers to the builder in the form of cost. No free lunch.

So if you are offering (as a manufacturer) to ease the burden on the builder, then how about setting up an efficient manufacturing facility and welding a tube structure together in large subassemblies or whole fuselages?

The point is, YOU (the manufacturer), determine the most efficient means to satisfy your market after doing an analysis OF that market. You don't force a manufacturing method upon your market. That's the cart before the horse.
 
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