Tail structure sizing

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Foundationer, Aug 20, 2018.

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  1. Aug 21, 2018 #21

    Chris Young

    Chris Young

    Chris Young

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    I calculated mine with FAR23 rules, then a friend said he used a Cl of 1.1 with uniform spanwise distribution on the tail, and the two chordwise distributions given in FAR23, and when I checked it amounted to almost the same thing. For an aerobatic airplane you have to consider the unsymetrical case described in FAR23 in addition to that.
     
  2. Aug 21, 2018 #22

    Mad MAC

    Mad MAC

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    The old FARs are still on the FAA website, just click through to the historic regs, it just gives all versions of the FAR23 regs (its browser sensitive).
    https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameSet

    Otherwise Abbott Aerospace has a copy of the FAR23 at Amendment 63 (the last Amendment it was of actual use).
    https://www.abbottaerospace.com/faa-part-23-pre-september-2017
     
  3. Aug 21, 2018 #23

    pictsidhe

    pictsidhe

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    The historical FARs on the FAA site are unreadable in Chrome and Firefox, what browser does it work in? See post 14 for a Chrome example. RDJ posted a usable site in 18. I haven't tried Abbot, but his stuff has always worked for me before. I've ordered a really cheap hardcopy AMT thanks to rdj's suggestion.
     
  4. Aug 21, 2018 #24

    Topaz

    Topaz

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  5. Aug 22, 2018 #25

    Mad MAC

    Mad MAC

    Mad MAC

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    Explorer of course (plus probably what ever MS product that replaced it).
     
  6. Aug 22, 2018 #26

    pictsidhe

    pictsidhe

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    People still use that? I've not used Exploder in about 20 years. I suspect it's a bit funny about running on a Linux system, too?
     
  7. Aug 27, 2018 #27

    Pete Plumb

    Pete Plumb

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    I wouldn't stress too much about this unless you are really cutting strength/weight to the minimums (like man-powered stuff or ultimate fuel economy, single-purpose stuff etc). If the aspect ratio of your tail is 3 to 3.5, the slope of the lift curve is going to be pretty shallow and max CL won't be over 1 - especially considering that most tail's reynolds numbers are going to be low too. I asked Ray Morgan what he uses for max CL on the tail and he said not over .8. If it is a higher aspect ratio it could be of concern if you keep your thickness ratio normal. If you work the FAR 23 load calculation back into a max CL it comes out REALLY low like .6 or something as I remember. If you go 1.0 at maneuvering speed you are going to be way conservative. Then do a shear and moment diagram and look at the loads and how they are distributed, add the hinge moments and you'll be amazed at light the structure has to be. Somebody mentioned fatigue and THAT would be my concern and a reason to beef it up from there especially if there is dynamic flexibility in the support structure. Hope this helps.
     
    pictsidhe and fly2kads like this.
  8. Aug 28, 2018 #28

    proppastie

    proppastie

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    Last edited: Aug 28, 2018
  9. Aug 28, 2018 #29

    pictsidhe

    pictsidhe

    pictsidhe

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    My $5.50 copy of 2015 FAR AMT turned up. I do prefer paper if I'm flicking back and forth.
     
  10. Aug 28, 2018 #30

    pictsidhe

    pictsidhe

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    I'm hoping to make much extensive use of coroplast. call me paranoid, but I want to run the numbers on everything...
     
  11. Aug 28, 2018 #31

    Pete Plumb

    Pete Plumb

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    Oh, I see. I must admit my knowledge is limited to standard materials and construction. I have no idea how you'd ever figure Fbu, Ftu, Fcu on that stuff. Sorry I couldn't help. Good luck on your project.
     
  12. Sep 6, 2018 #32

    wktaylor

    wktaylor

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    Fud-4-Thot... Might find the following useful.

    NASA TN D-6575 SUMMARY OF SPIN TECHNOLOGY AS RELATED TO LIGHT GENERAL-AVIATION AIRPLANES

    FAA AC23-9 EVALUATION OF FLIGHT LOADS ON SMALL AIRPLANES WITH T, V, +, OR Y EMPENNAGE CONFIGURATIONS

    NASA CR-195496 Aircraft Empennage Structural Detail Design

    Airframe structural design: practical design information and data on aircraft structures, Michael CY Niu
     

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