Tube framing software...

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LArzfromarz

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Does anyone have a suggestion for a software package that will help me design (properly) the tube framing for an original design EAB.
Actually any direction towards design of the frame components would be helpful.
Appreciation in advance....

Larry "LArzfromarz" Romig
 

bmcj

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That would probably be a simple FEA (Finite Element Analysis) program and a good table of materials properties for tubes.
 

LArzfromarz

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Are you talking about a CAD program or an analysis program for truss frames?
Actually both to be prudent.
Truth is I'm probably out of my depth on the analysis part. I can understand the results easy enough and the goals are the same as everyone (except the boat builder guy), strength and light weight.
I can see everything in my head and have flown the basic design in X-Plane, so I can get the idea into pixels.
I don't really want to spend the next 6 months learning a software package just to get started.
Again I think I know what the frame should look like, or I know form I'd like it to be in.
BTW, 2-place, side by, high wing pusher, w/twin tail booms. 4130 frame, Al wing, fuse comp covered. Jab 3300, center mounted drum fed .50 cal, 2.75" rockets under the wi... oops never mind the last parts.

Any volunteers? (small v not the Tenn kind:gig:)

You guys are great-
Larz
 

Mac790

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Actually both to be prudent.
Here ia a long thread about CAD software
http://www.homebuiltairplanes.com/forums/design-structures-cutting-edge-technology/5025-what-software-do-you-use.html

About FEA you don't have too many options, there is a Femap demo version but it's almost completly useless, it has 500 nods and only about 50 elements limitation (I was able only to create about 30% of the Acro Sport fuselage).
I heard that the ABAQUS has 1000 nods limit in demo version, so it should be much more useful.

Seb
 

Topaz

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Does anyone have a suggestion for a software package that will help me design (properly) the tube framing for an original design EAB.
Actually any direction towards design of the frame components would be helpful.
Appreciation in advance....

Larry "LArzfromarz" Romig
If it's a simple tube truss, it may be a more efficient use of your time to simply study a bit and do the calculations "the old-fashioned way", albeit with a calculator.

You're going to have a long learning curve on any software package that is worth the money you pay for it. If you're only doing this once (one airplane design) or even twice, that's a lot of time and effort (and money!) to use a tool that you won't ever use again. Wheras a book and a good calculator might set you back less than $100.

Remember, even the SR-71 was designed with pencil, paper, and slide-rule. ;)
 

bmcj

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Topaz is right. Simple truss structures can be calculated by hand without too much difficulty. It's just a matter of summing your forces and at each node to determine the tension or compression in each of the elements. It only becomes difficult if you build in too many elements and create a statically indeterminant structure.
 

LArzfromarz

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While I don't have any software towards this end I was considering something like SOLIDWORKS. I heard it was fairly heaving on the learning curve but you can get student editions at reduced pricing.
What I really need to do is post the following to give you an idea of the shape...
Actually the "chines" down the sides of the fuse are -71 inspired-
Larz
 

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PTAirco

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About FEA you don't have too many options, there is a Femap demo version but it's almost completly useless, it has 500 nods and only about 50 elements limitation (I was able only to create about 30% of the Acro Sport fuselage).
I heard that the ABAQUS has 1000 nods limit in demo version, so it should be much more useful.

Seb
Hm, I have not run across a limit on the number of elements for my free FEMAP demo version. I only use it to model the fuselage and find the axial loads (and maybe a handful of beam elements thrown in) then check them for buckling by hand, which is all you really need. For that it is immensely helpful.
My older NASTRAN demo had the same 300 node limit but was far more user friendly, but only runs on WIN98.
 

Mac790

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Mac790 said:
it has 500 nods and only about 50 elements limitation
500 nodes? hmm of course 300 I don't know where that 500 came from.

PTAirco said:
Hm, I have not run across a limit on the number of elements for my free FEMAP demo version. I only use it to model the fuselage and find the axial loads (and maybe a handful of beam elements thrown in) then check them for buckling by hand, which is all you really need. For that it is immensely helpful.
My older NASTRAN demo had the same 300 node limit but was far more user friendly, but only runs on WIN98.
I don't understand it either, check out these attachments, it's everything what I can do with demo version, there are 124 nodes, and 142 elements (about 46 "line"/beam elements, and 96 mesh elements). I don't know how to explain it, but it seems like there are two type of elements, because I can't add more new elements (like new lines/beams) but I can add more mesh elements. Maybe your version of the Femap is a little bit different.
I was really "unhappy" because after a few hours of "putting" all those coordinates X,Y,Z I wasn't able to save it, I had to remove more than a 50% of the fuse. In result I didn't play to much with constrains, I just chose two all fixed, it was pointless anyway.

Seb
 

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Ivan

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My truss software of choice is GRAPE. It's available as a freeware download. There's a bit of a learning curve, but it does the job for me. Hope it's useful.

Ivan
 

heytwo

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Spreadsheet software . write your own CAD .

--------------
I will be making some frames using bicycle methods .

100,000 PSI CRS steel tubes ,brazed into steel lugs .

Bicycle frames dont break , brazing is more reliable

than TIG .

Im buying Yamaha R1 engines . wt is 120 lbs , 188 H.P.
chain drive ( like the Wright Bros ) .
 

autoreply

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Spreadsheet software . write your own CAD .
I was once told that the highest grossing software in aerospace is Microsoft Excel. Consider that excel is 100-500$, Catia and more specific stuff is above 10.000..

Having said that, even undetermined structures can without the slightest problem be solved with Maple/Matlab and it takes you maybe a couple of hours to set up everything. That way you can still easily vary material properties, lengths, dimensions.
 
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