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Thread: A complete report on the aerodynamic and strength design of an ul aircraft

  1. #1

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    A complete report on the aerodynamic and strength design of an ul aircraft

    My name is Christos and i am a civil engineer and aviation enthusiast from greece. First of all i would like to thank you all for your interesting and useful threads. It helped me throughtout the design. Now i am going to build my own design 2 seat ultra light composite aircraft. For the design and development of the aircraft all tools available to the modern engineer have been properly used.
    This is the technical report of the design.


    I posted it also in one other forum. I hope that you don't have any problem. Your forum and other was really helpful and i thank you about it


    Best regards!

    https://www.lisafea.com/citations.html
    https://lisafea.com/pdf/Design_of_Ul...t_Aircraft.pdf

    I hope you like it

    (original post) http://www.homebuiltairplanes.com/fo...ad.php?t=30737

  2. #2

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    I also made some animations
    1)Pressures around the aircraft at speeds just before stall with fully extended flaps



    2)Airplane hard landing (non-linear impact analysis)



    It will be operate as ul in europe (it is light enough for uk's regulations) and as an lsa in usa

    Best regards!

  3. #3
    I can't add anything technically valuable, but it does make for an interesting read, and I cannot wait to read more about it.

  4. #4

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    Christos;
    Why did you choose 6.00 X 6 tires for a light plane? I would assume 5.00 X 5 would be more than sufficient for normal operations and would provide less weight and frontal area.

  5. #5

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    Quote Originally Posted by Bob H View Post
    Christos;
    Why did you choose 6.00 X 6 tires for a light plane? I would assume 5.00 X 5 would be more than sufficient for normal operations and would provide less weight and frontal area.
    Dear mr Bob,


    I choose it because of better behavior and comfort on rough concrete surface. In near future i will change. But for the test flight i believe that it is safer a bigger tyre. I will operate from a rough concrete airfield.
    Additionally i make this report to receive a flight permit, and i had to select tyres and i selected test's one. Of course i can change it. I am planning to change it after the test flight (if everything goes well).


    Do you like technical report? It is a 100% computer design, i run in fea software every bolt every element and for computational fluid dynamics analysis i pay for a really strong computer. Last but not least i also ran a flutter analysis. It is an integrated design


    Thank you very much for your interest!
    Last edited by christos; 11-16-2018 at 07:44 AM.

  6. #6

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    I spent many years working on composite manufacturing for aircraft. I didn't see any details of the actual composite structural scheme you used; skin/stiffener, sandwich. Or any fiber/matrix choice.
    I fly a Pulsar experimental with E-glass, 10 mil sandwich skins and 1/4" honeycomb overexpanded core. Very light/stiff structure. Used 180F cure epoxy resin matrix.

  7. #7
    I am not an engineer but question the use of the NACA 66-009 airfoil. Although this airfoil has a very low drag coefficient in the very narrow laminar drag bucket it also has a poor lift to drag ratio. My understanding is that an airfoil with a better lift coefficient would allow the use of less wing( less drag ) and have better flight characteristics from cruse through stall. The NACA 66-009 would have a root thickness of approximately 0.117m or 4.5 in which would need a very strong spar at the root and have very little room for fuel. Also wouldn't the flaperons on such a severe stall airfoil cause an adverse yawl stall spin scenario?

    Otherwise it should be a good motor glider and excuse my ignorance.

  8. #8

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    Quote Originally Posted by Bob H View Post
    I spent many years working on composite manufacturing for aircraft. I didn't see any details of the actual composite structural scheme you used; skin/stiffener, sandwich. Or any fiber/matrix choice.
    I fly a Pulsar experimental with E-glass, 10 mil sandwich skins and 1/4" honeycomb overexpanded core. Very light/stiff structure. Used 180F cure epoxy resin matrix.
    Dear Bob,


    It is a technical report of aircraft's analysis and i didn't include structural details.
    I am proud and lucky to discus with you because you have a lot of experiense. This aircraft will have a little greater top speed and lower stall speed than pushar because of their design. You will understand if you take a look at cl-aoa graphs.
    About structural analysis, only a few aircrafts are so well analyzed. Finite element analysis of structure is high level, it is as good as a car's one.
    About skin etc, itsn't so simple to me to answer in your question because it combine a lot of deferent materials, high strength pasticity zones, a combine of uni kevlar-carbon epoxy sandwich, in the first front area, high strength zones around passenger, a combine of carbon bars and glass epoxy laminate, wing spar, a combine of carbon tubes in high tension areas and epoxy laminate, it is only a simple report. This design is more complex than you believe.
    I am a civil engineer i studied in university for 5 years and i also have a cfd analysis certification. But i would not do it if i had not some good friends whose helped me. I refer them in technical report.

  9. #9

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    Quote Originally Posted by David Bally View Post
    I am not an engineer but question the use of the NACA 66-009 airfoil. Although this airfoil has a very low drag coefficient in the very narrow laminar drag bucket it also has a poor lift to drag ratio. My understanding is that an airfoil with a better lift coefficient would allow the use of less wing( less drag ) and have better flight characteristics from cruse through stall. The NACA 66-009 would have a root thickness of approximately 0.117m or 4.5 in which would need a very strong spar at the root and have very little room for fuel. Also wouldn't the flaperons on such a severe stall airfoil cause an adverse yawl stall spin scenario?

    Otherwise it should be a good motor glider and excuse my ignorance.
    I used naca 66-009 only for vertical and horizontial stabilizer. I didn't publish main's wing airfoil. I don't answer in other question because i think it is on naca 66-009
    Last edited by christos; 11-18-2018 at 03:04 AM.

  10. #10

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    Stress forces resulting from a dynamic responseanalysis (for loads in flutter condition) in the LISA finite element program.

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