Done with reading, time to discuss

Discussion in 'New Member Introductions' started by yellow_submarin, May 10, 2013.

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  1. May 10, 2013 #1

    yellow_submarin

    yellow_submarin

    yellow_submarin

    Well-Known Member

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    Hi everyone

    I am a 22 years old aerospace engineering student from France. I have flown for many years models and paramotors. I now wish to scale things up :)

    I have since 4 months a projects that takes most of my time. I'm into building an ultralight under the french ULM regime (450 kg mtow, 65 kmph stall, 100 hp). I considered at first building an improved Sonerai, for speed and mostly aerobatics, mainly using composites. I finally found out what I really desire above all is an amphibian. I have witnessed many similar designs that could be greatly improved. I want to get the maximum performance out of this machine, to get a jet-fighter-like feeling, which implies manoeuvrability, speed (between 250 and 300 kmph), and range, as I would like to travel with my girlfriend.

    I have spent the last months reviewing most existing aircraft designs, and inventing some, to sort out what could be used. So far, I have come to the conclusions that I it will be featuring :

    - Double shrouded propellers
    - Tandem seating
    - T tail
    - Low aspect ratio, low surface wing, GAW-1 airfoil, highly effective flaps and slats
    - Canard for trimming

    Please join me on the design thread I'm about to start !

    Thank you all for this wonderful forum which provided me with important information and different considerations I wouldn't have had on my own.
     
  2. May 10, 2013 #2
    Most welcome to the house of the crazy nuts bro ...
    I advice you to have things written .. meaning to start the design and show it in here for others to discuss ... stating all possible info is a most so our opinions can be relative to your requirements ...

    Go for it man .. don't wast more time ..
     
  3. May 10, 2013 #3

    Xanadrone

    Xanadrone

    Xanadrone

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    Welcome - glad to see other european HBA-fans around here!
    As for your plan, I'd really be curious to see the design of a hydro-canard, since I don't know many around... in fact none, if I'm not too superficial (might be some problems in the take-off phase I guess).

    P.S. The GAW-1 is indeed an "universal" airfoil and the data available is huge - one example: http://www.reaa.ru/yabbfilesB/Attachments/19770018139_1977018139.pdf
     
  4. May 10, 2013 #4

    yellow_submarin

    yellow_submarin

    yellow_submarin

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    Thanks for welcoming me. I have already posted my design thread in the appropriate section.

    Yes, the GAW seems to fit pretty well for my flight enveloppe, and there is indeed a lot of date, such as for flaps, which is definitely useful. Thansk for the link, I had already been through though. Small detail, I will have a canard for trimming (as the GAW features a high pitching moment), but the pitch authority belongs to the tail group.
     
  5. May 11, 2013 #5

    Southron

    Southron

    Southron

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    You might want to check out Vortex Generators (VG's) as they will reduce your shorten your Take-Off Run and Landing Distance a bit-not to mention they will reduce your stall speed a tad.
     
  6. May 13, 2013 #6

    captgrizz

    captgrizz

    captgrizz

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    I am assuming you are planning on a flying hull type as fast goes out the window with pontoons. Designing a hull with a good step feature that will promote fast water taxing and getting off the water fast is very important. Is 100 HP your upper limit or just a basic starting point. I would recommend a EA-81 or 82 Subaru engine with a little flow work done on the heads and a High Torque cam that makes max torque @ 4600 to 4800 RPM use a 2.8 to 1 Prop Speed Reduction Unit So you can run the engine at peak efficiency and turn a much larger propeller at its most efficient speed. (note larger props are much more efficient than smaller props in terms of thrust per HP assorbtion) There is a possibility that the EA-81 or 2 will develop a bit more than 100 HP as I got around 105 HP out of the 1600 CC little brother to that engine. But I modified it a bit more than most folks would recommend for use in aircraft. I did however run it for a bit over four thousand hours on a test stand with a prop off a 150 HP Cessna at full 4600 RPM power with a 2.56 to 1 reduction if you do the math it will work out to roughly 105 HP assorbtion on the prop. GOOD LUCK on your designing and I hope I was of some help but my engine choice may exceed your weight limits. GRIZZ
     
  7. May 13, 2013 #7

    captgrizz

    captgrizz

    captgrizz

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    I bought plans for an Osprey II but built something a bit larger although very similar. In his introduction George Pereria talks much about what he went through developing the hull for his plane and getting the step not only in the right place but in the right shape to get the most efficiency in the design. GRIZZ
     

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