Aluminum Tube & Gusset Airbike / Legal Eagle / Parasol Thread

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Victor Bravo, Oct 8, 2019.

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  1. Oct 13, 2019 #161

    radfordc

    radfordc

    radfordc

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    You could look at the common T&G examples and copy them. Aerodrome is what I'm most familiar with and they tend to use 1" tubes in the aft fuselage and a larger size in the front.

    I personally wouldn't go for "equivalent strength", I would go for stronger than needed by a good amount which is how I think Robert Baslee designs his.
     
  2. Oct 13, 2019 #162

    FritzW

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    Just sayin... If Baslee overbuilt (overweight) his designs and Aerowerx uses his designs for "inspiration" and goes stronger by a good amount (more unnecessary weight) ...things are going to start getting pretty heavy.

    There's a neat chart in the Evans Lightplane Designers Handbook that lists the "Properties and Allowable Ultimate Tension, Bending and Torsional Moments" for 2024 and 4130 tubes. It lists them by OTS sizes and you read the properties in the 2024 or 4130 side of the cart (you'd have to interpolate for 6061). The LPDH also has the column load curves from the Summerill charts.

    The Summerill charts are available from a google search. I don't know which ANC the 2024/4130 comparison charts were copied from but they could be scanned and posted. It wouldn't be copyright violation because they were cut and pasted from a govt. pub to begin with.

    Be careful with just copying the tubing size from another design, the geometry is just as important "The strength of a rectangular beam is proportional to its width times the square of its depth", and the fuselage is a rectangular beam.
     
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  3. Oct 13, 2019 #163

    Pops

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    Please don't tell me that. I have about 6 designs I would like to work on and build. The BeetleMaster is just one.
     
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  4. Oct 13, 2019 #164

    FritzW

    FritzW

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    At my age I forget the new ideas I had a few months ago so when I have them again they count as "new".

    P.S. I've spent many hours with a set of Skymaster RC plans trying to get a twin VW O2-A to look right. ...I can make it look right or I can get the CG to work out but not both ...yet
     
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  5. Oct 13, 2019 #165

    Tiger Tim

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    I’ve waffled back and forth on whether my fantasy Verner Solocoupe should be wood (stealing heavily from the Hi-Max) or aluminum tube with a pile of inspiration from Graham Lee. I’m watching this thread with interest.
     
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  6. Oct 13, 2019 #166

    cheapracer

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    LOL! With Alzeimers you get to meet new people everyday.

    .. and there's this hot looking lady who hangs around inside my house everyday too, might try my luck there ....
     
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  7. Oct 13, 2019 #167

    addicted2climbing

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    The best thing about Alzheimer's is you can hide your own Easter eggs....
     
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  8. Oct 13, 2019 #168

    radfordc

    radfordc

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    I'm not suggesting you need a structure stronger than those designed by Robert....his are already more than strong enough. I'm saying that trying to build a T&G structure that matches the strength of a wood structure isn't necessarily a good idea. If you are designing to minimum weight and minimum strength you must be a good engineer and should probably test structures to confirm their adequacy. An overbuilt structure will always be heavier than it could be, but as long as it performs acceptably that isn't a problem.
     
  9. Oct 13, 2019 #169

    ScaleBirdsScott

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    I'm on board with the idea of a single-seater designed after the Monocoupe radial. It's along the same sort of lines I've been thinking.

    I definitely would say for optimal lines on something of the aesthetic, I would... favor welded steel.

    T&G would do it. But for T&G I would not get too fussed with trying to replicate the classic aesthetic as much. Definitely would aim for a more utilitarian package while keeping some clean lines in mind.
     
  10. Oct 13, 2019 #170

    Aerowerx

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    Did you read my post, to which everyone is responding?

    I said match the strength of the wood structure as a starting point as to the T&G structure. And then also do the engineering calculations to confirm. Of course, testing after construction.

    But if a wood structure is designed to fly at 'A' knots, with +/-'B' g load, and you pick your aluminum to match the strength of the wood, shouldn't the T&G design have the same characteristics?
     
  11. Oct 13, 2019 #171

    David L. Downey

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    ...I am not getting testy. But as I stated in my comment, a career in structural test is perhaps more valid than the opinions of a sales or "engineering sales" rep at a fastener company. even our low and slow airplanes suffer from low cycle fatigue..and that is where these issues show up. People can indeed skip proper deburring as it is a pita, but the longevity and security of the airframe are compromised - every time. As someone said, Cogsdill makes lovely tools that are prices but last forever in aluminum. when properly set they deburr effortlessly. Another advantage of deburring in process when skinning with aluminum is less puckered skins on final assembly as the line length is not different between the structure and skin. I do acknowledge that deburring does add time to the task. I disagree that it is not worthwhile.
    I also am one who has never been able to become a good welder in over 40 years of trying - and I own decent equipment in all the types of welds!
    I will let this drop now as there is no place for antagonism in a help forum.

     
  12. Oct 13, 2019 #172

    mullacharjak

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    Cheapracer

    That looks like a VP1 fuselage to me !
     
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  13. Oct 13, 2019 #173

    BJC

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    I would want to verify that the load carried by any plywood skins would be carried in the (presumably fabric covered) tube and gusset structure. That could require additional tube structure. I would want to verify that the tubes would not buckle under ultimate load. I would want to verify that the stiffness of the tube and gusset structure was adequate. I would want to verify that all hard points are adequate, with close attention to the control surface hinges. I would not assume that the tube and gusset fabric covered structure would have the same Vd as the wooden structure. I would be more concerned about fatigue in the tube and gusset structure.

    Given all of those issues and concerns, I would consider that the tube and gusset structure needed to be a completely new design. That is not to say that a “copy” design will not fly; however, if would be pleasant coincidence if it was close to an optimum design.


    BJC
     
  14. Oct 13, 2019 #174

    mullacharjak

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    The DSK Delta style of wing spar construction was a type of tube and gusset construction which has been forgotten.
    Combined with the fisher style of fluted angle rib would result in a very nice structure.
    We dont have aluminum tube/sheet here so I am just sharing my idea.I am sticking to wood as
    that is all we have.
     
  15. Oct 13, 2019 #175

    Tiger Tim

    Tiger Tim

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    What’s out there for wing and strut mounting options on an aluminum tube cabin plane? I’m picturing a square steel carry-through across the top and steel strips tying in the struts across the belly. Is there anything more elegant than that?
     
  16. Oct 13, 2019 #176

    Victor Bravo

    Victor Bravo

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    A heavier wall aluminum tube as one of the crossmembers on the bottom, with bolted or riveted attach tabs.
     
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  17. Oct 13, 2019 #177

    Toobuilder

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    And taking a lesson from the Challenger (IIRC), that is one load path that needs to be engineered and fabricated very carefully. No second chances with that one.
     
  18. Oct 13, 2019 #178

    cheapracer

    cheapracer

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    At no point anywhere did I say not to deburr, it is indeed quite important, and I mentioned the 2 methods i use to deburr above, i.e. a 14mm drill in my hand and a modified allen key for inside the tubes. Most intelligent people realise I use them for deburring.

    What i am saying to people interested in this method of construction is that you don't have waste your time making love to every one of 5,000 to 10,000 holes, nor do you need special skillsets or tools.

    As long as all major burrs are removed, and there is no raised surfaces to interfere with the 2 surfaces mating to each other, you're good to go.


    You have no idea who I was dealing with in those major rivet manufacturing companies, that is just consescending arrogance on your belief you are superior to others, for which you will now be put on my ignore list, as I don't want to see your self importance again. The irony here is all your practices came from those, or similar sources.

    My purpose here, and the bulk of all my other posts around here are to encourage people that they can do it, and most things are nowhere near the stress and as hard as 'Experts', like you, make them out to be.

    Bye bye.
     
  19. Oct 13, 2019 #179

    cheapracer

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    The Morgan foundation was a KR2, though much extended. It even has some carry overs from the KR2 such as the fuse being 'fat' in front of the wings and the fuel tank position etc.

    http://www.krnet.org/krs/lhyder/
     
  20. Oct 13, 2019 #180

    Victor Bravo

    Victor Bravo

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    Trust me, there would be far more formal engineering in that structure than there is water in the ocean !
     

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