# Aluminum Tube & Gusset Airbike / Legal Eagle / Parasol Thread

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#### cheapracer

##### Well-Known Member
Log Member
Our aluminum tube frame was quick to build and stupidly strong. And I agree the double sided gusset is going to outlast notched tube for preventing out of axis wiggles and rubbing. We left an air gap. I would think the only time I want notched tubes butting against each other is if we're about to heat and fuse those suckers. Rivets will not prevent vibration from slowly deforming that joint over the years until it's loosey goose.

Now will any riveted tube and gusset variation last 60 years of hard flying like a 4130 bush plane? I'm not sure. But we could slap one together in a weekend with no special skills or techniques.
Yup. 20+ years for the Morgans and no issues at all.

For an aircraft designed for quick assembly, why bend tubing or angle? Just create the frame from straight sections and gusset them together at whatever angles are necessary to build the structure.
Yup, it works.

The welded 4130 frames have a great reputation for protecting occupants in a crash. I do wonder how an AL gusset frame would compare in crashworthiness if built to the same weight as the analogous 4130 frame, and with crashworthiness as a specific design objective (e.g. beefier tubes, gussets, triangulation where needed to keep the front from collapsing into the cabin, etc). Maybe a few more pounds of AL in the right spots could make the structures close to the same in this regard, and retain the ease-of-construction advantages of AL tubes and gusseted joints. There have been Sonexes that did a very good job of protecting the occupants.
Couple of Morgans have been crashed, the upper and lower square tube longerons are 1" x 1/8" thick, and have proven to be very robust in the incidents.

Square tubes will have the same problem as angles. It will twist when you try to bend it, particularly in compound curves, like the lower longeron in most tube and fabric designs.
Nope, square is fine, have done it.

Litespeed beat me too it, but i have mentioned the Morgans, oh a 100 times i guess before, and all your questions are answered.

Having actually built one, it's a the bees knees for simplicity and ease of construction.

Look and learn is all i can say, many of you are making life hard for yourselves otherwise.

https://www.recreationalflying.com/forums/topic/13034-sierra-100-kit-build-underway/

https://www.recreationalflying.com/forums/topic/15291-morgan-sierra-100/

4 seater

https://www.recreationalflying.com/forums/topic/11815-started-the-couger/

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#### FritzW

##### Well-Known Member
Log Member
But if the cleco holes are already located in all the parts, what does the printed assembly aid alignment tool do?
They'll make sense when you see them. (I gotta figure what airplane to put them on first. ... TnG single seat 701/750? ...TnG Ranger'ish? )

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#### FritzW

##### Well-Known Member
Log Member
Obviously, if we add machine time and setup, it would cost more (i.e. if our homebuilder takes the thumb drive to a local Maker, ...a small kit for those who would rather not mess with printing the parts).
I imagine the files would just get uploaded to thingiverse. The builder could print them himself or have them printed. Some enterprising entrepreneur could print up a few sets during the down time on his printer and make a few bucks.

#### rotax618

##### Well-Known Member
Yes the Ferris wheel was quie close to the airstrip, but how you couldn’t see a Ferris Wheel I don’t know.

#### plncraze

##### Well-Known Member
HBA Supporter
You Australians are cool! We only hit trees. Thank you for the picture. That's even stranger than I pictured it.

#### ScaleBirdsPaul

##### Active Member
View attachment 89352 Yes the Ferris wheel was quie close to the airstrip, but how you couldn’t see a Ferris Wheel I don’t know.
That's just wild. Doesn't appear to be the most sturdy Ferris wheel either, surprised it all held up.

#### Aerowerx

##### Well-Known Member
That's just wild. Doesn't appear to be the most sturdy Ferris wheel either, surprised it all held up.
Ferris wheels are not designed to be hit on the side by something traveling 100+/-mph!

#### litespeed

##### Well-Known Member
That Ferris wheel is infamous.

It was placed next to the runway and way too close. Easy to hit it, your in a low wing and its below your line of sight as you approach. The piloting is another issue but no one expects a ferris wheel to act like a bird spider and catch you from the air.

Even made the news in Russia- they like the weird crashes. The upshot is the aircraft was not a right off and was rewinged and flying again shortly after.

The poor kids in the chair got quite a shock.

#### litespeed

##### Well-Known Member
Looks like an aluminum KR2. Quite a line of interesting designs. http://www.morganaeroworks.com.au/cheetah.html
Right on the money, just bigger, roomy, has good storage and Aussie strong.

Gary Morgan actually made a variant of the KR2 called the Joey- a fast little beasty but moved on to the Sierra and other designs for faster build, more room and cheaper to make. Hence a metal plus sized Kr2. The Joey is a 165 knt aircraft and the Sierra some have 150 knt on a variable prop. So not slow for a LSA.

#### litespeed

##### Well-Known Member
A few more pics- note the long gentle curve of the lower longerons which curved up and inward.

No issues with too much tension or tube rippling. Dependant on the builder extra strength can be added by skinning the inside of the cockpit as well as the outside. When added to gussets and the big strong tubes, the double skin makes a hugely strong cockpit.

Note the simple jigging with a flat table some clamps and straps. All easy stuff and a handful of tools.

#### pwood66889

##### Well-Known Member
Now this is what I'm talking about, Speed. "Design for Assembly." What caliber square stock was used?
And sorry bout the bloke on the Ferris Wheel...
Percy in NW FL, USA

#### Aerowerx

##### Well-Known Member
Now this is what I'm talking about, Speed. "Design for Assembly." What caliber square stock was used?
And sorry bout the bloke on the Ferris Wheel...
What?????

#### Toobuilder

##### Well-Known Member
Log Member
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?

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#### Kyle Boatright

##### Well-Known Member
S

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?
The discussion is about a method which would allow Joe Schmoe to put together an airframe using a handfull of clekos and a pop rivet gun or puller.

I think that is a great solution for some airframe types.

Is anyone gonna get rich off of one or two place low and slow airplanes? Probably not, but the idea might put the \$15k, easy to build airplane within reach.

#### proppastie

##### Well-Known Member
Log Member
The RV method as a set of printed templates would be an interesting design of a plans built aircraft. I do not think one needs a CNC router or 3D printer to make it work.

#### cheapracer

##### Well-Known Member
Log Member
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.
No, it comes down to the engineering on each design actually, but what i will counter with is the single most important fact of them all...

... just about every Morgan kit ever sold has been completed by complete novices building them. There's over 50 flying.

That's the winning margin.

Looks like an aluminum KR2. Quite a line of interesting designs. http://www.morganaeroworks.com.au/cheetah.html

The fuse is a bit of a copy of a longer KR2S, but the wing design is brilliantly simple, worth investigating.

Note the wings are offset longitudinally to alow the crossover, and one spar faces forward, the other rearwards, it's an Asperger's nightmare!

Gary Morgan actually made a variant of the KR2 called the Joey-
I own the Joey 1 and 2 fiberglass molds.

#### pwood66889

##### Well-Known Member
Please accept my apologies for "Fat Fingering" my last post somehow... Kyle said it better - this thread seems to have became "about a method which would allow Joe Schmoe to put together an airframe using a handfull of clekos and a pop rivet gun or puller."
And I am still sorry about the blokes with the Farris Wheel....

#### ScaleBirdsScott

##### Well-Known Member
I think the idea is not everyone ends up with their own CNC and makes everything from plans. The idea is maybe a few simple small designs could be made, and then from that some batches of kits could be made by those who have the tooling to CNC stuff. If you have your own CNC router at home (more and more common) then you can start figuring out how to cut the parts.

And why not? If someone thinks it's faster to weld, there are hundreds of kits that cater to welding. Meanwhile a lot of people have never, and will never ever, weld steel in their lives. You could give them a welder and all the rod and PPE. And they'll still be hugely hesitant to weld some thin wall tubing into a cage in which they're going to hang from a pair of wings.

Drilling and riveting is so easy that with a properly setup pull riveter someone's 10 year old can create airworthy clusters in minutes. And ones that can be easily checked by a rank novice. I don't think anyone is going to trust the welds of a 10 year old who hasn't touched a TIG torch or a Oxy/Acetylene torch before 10 minutes prior. And if the person instructing them isn't an experienced welder, they won't be able to judge whether that weld is good or not in the first place.

#### cheapracer

##### Well-Known Member
Log Member
this thread seems to have became "about a method which would allow Joe Schmoe to put together an airframe using a handfull of clekos and a pop rivet gun or puller."
Err, yeah, tube and gusset as per the thread title ....

I'm trying to promote a known technique that is available to every homebuilder, and tends to get finished.

And I am still sorry about the blokes with the Ferris Wheel....
It's just becoming a circular discussion.

#### FritzW

##### Well-Known Member
Log Member
weld a 4130 structure faster than I could program, drill and pop a aluminum copy.