Lots of aircraft have indeterminate structures. Many are simply over-built, or copies / extrapolations of existing successful designs.
If you want to analyze your indeterminate structure, look into the virtual work method.
The Airbike is the answer for your request, or the Affordaplane and it’s derivatives.Reminds me - when rebounding from an aeromedical decline, I purchased a Loehle Parasol. The cockpit access involves sidling around the three wing struts (count 'em) then lifting a foot over the cockpit wall to place it on the seat, and rising in a crouch to avoid the overhead wing, then shuffling legs into position, remembering to confine the feet to reinforced structure - after fifty years of opening a door and stepping in (a Cessna 150). What I REALLY need is a sidewall cutaway. Toying with a square tube warren girder connecting the forward structure to the rearward structure, so I can step in more gracefully!
Looks Great Ollie,Hi Home Built Airplane Enthusiasts,
We're working on designing a gusseted aluminum truss frame which resembles the Legal Eagle and have been really struggling with some of the more complex joints (places where 3+ beams come together on separate planes. We opted to use a gusseted aluminum frame since we noticed many people have an unusually strong aversion to welding and using a gusseted frame would remove the need to cope all the beams. Throughout our design process, we've run into several gnarly gusset problems. We were able to solve most of them but there is one that we just can't figure out a way to connect. A gusseted aluminum truss frame isn't very uncommon so I would imagine it's possible to do but I was wondering if y'all could point us in the direction of some resources and documentation we can read which may help in this situation. We can adjust the truss layout however necessary and if we can't solve this gusset problem, we can use a welded 4130 frame. Even if we are able to solve this gusset problem, though, we want to strike a balance of simplicity and ease of construction. If our complex gusset joints become too difficult to construct, it may be simpler just to weld the frame despite people's aversion to it. Below I've attached some screenshots of some of our latest truss design and failed gusset attempts. Home Built Airplanes has been an invaluable resource over the course of our project and we are extremely grateful for all of the experienced advice and crucial insight you all have given us.
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Also maybe consider 3D printable fixture that holds all the tubes in the exact right orientation for fixturing, at which point that block can be abandoned in place or removed/discarded.
I don't know anything about cast aluminium strength, but seeing guys on the interwebz casting with 3D printed pattern and "lost PLA" technique, you wonder what's possible nowadays? Not easy at all, but you can't stop wondering...Also maybe consider 3D printable fixture
If the tubes in the cluster all point to the same spot, the fixture might be composed ofAlso maybe consider 3D printable fixture that holds all the tubes in the exact right orientation for fixturing, at which point that block can be abandoned in place or removed/discarded.
Looks Great Ollie,
I am planning to redo the Skylite as tube and gusset eventually as well and will run into the same problem if I keep the tube interfaces and clusters the same as on the welded version. To fix your issue, maybe have a look at some of the Baslee Airdrome WWI fuselages to see how they get around it. My guess is they avoid multiple clusters intersecting other clusters in another plane. Also have a look at the Texas Parasol even though it uses angle aluminum. Maybe you will need to rethink your fuselage a bit now thta you have found a problem.
Some possible options:
A welded/brazed cluster 'stub' that the other tubes are socket-ed into/around?
Abandon the planer gussets in these areas and use a bent gusset that ties tubes in 2 planes together?
Use a second, overlapping gusset, to tie 2 intersecting "V" sections together?
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