New two seater jet aircraft from Sonex

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by saini flyer, Jul 11, 2019.

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  1. Jul 14, 2019 #61

    BBerson

    BBerson

    BBerson

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    I saw a picture of the young Monnett. Looked to be about 120 pounds. (not so light now but still short)
    The history has been to make a single seat then a similar two seat. But many owners can't get the two seat to perform as they want. One guy at Oshkosh with a Sonerai II told me he will never take a passenger.
    A small two seat trainer can work with a 120 pound instructor. It isn't fair to the 260 pound instructors that want to fly/teach in small airplanes. My mother in law told me life isn't fair. :D
     
  2. Jul 14, 2019 #62

    MikePousson

    MikePousson

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    I met Corky at an Airshow in Lake Charles in the 80s at some point. He was the featured act that year. He is a good guy. Pretty well grounded.
     
  3. Jul 14, 2019 #63

    Scheny

    Scheny

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    I knew an instructor who just fit your description :p. He was not only exceeding the per seat weight, but also 80% of the permissible load. He shouldn't have refueled even when flying alone.

    Still, most of his students were male, in their sixties and not of the skinny type. He had good connections, so our hope that a ramp check will reveal his miracle weight and balance sheet never got true...

    He also was a real asshole, but his fare was much lower than for the competition. I always tried to keep distance.
     
  4. Jul 22, 2019 #64

    Scheny

    Scheny

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    At the beginning of each aircraft project there is the constraint diagram. Designing an ultralight jet is one of the most challenging things to do, both due to the limited CG range and due to limited thrust from small turbojets.

    I will disclose the constraint analysis that our lead aerodynamic specialist created before we started the Beast project. The math behind it is filling multiple pages, but I will show the outcome, so you get the point:

    [​IMG]

    The constraint diagram shows a combination between thrust to weight (for jets, for piston it looks a bit different) and wing loading. It basically tells you where your journey will go in terms of wing area, aspect ratio, etc...

    You create constraints like your weight, your target wing area, take-off run, climbrate, stall speed, etc. and it will result in a curve for each constraint. Your plane will be feasible, if your T/W is above all lines. For propeller planes, it will look like U-shaped lines, but for the jet, they are looking rather like decaying exponential functions.

    As the jet is in the 1000N range the T/W will be only ~0.25, so the remaining area is rather small as you can see. The diagram will tell you, that the optimum plane (orange dot) will have a wing load between 200-250kg/m² resulting in a wingspan of 4.1m and 1.7m² wingarea. For this to work, the required Cl results to be in the area between 3.6 and 4.1. I will not comment on this, but you see, using state of the art calculations, it is impossible to build a plane like this. This is the reason, why our competition behaves sooo bad at low speeds and is exactly where we want to improve (not on top-speed like most guys).

    The JSX-2 has in reality a span of 5.5m with 5.6m² of area and a Cl of ~1.3. You see, that following state of the art designing technique, the T/W ratio should even be in the area of 0.5 to fulfill all constraints!!!


    It was hard convincing my aerodynamic guy to trust me such a plane could fly decently (even after showing him BD-5 and JSX-2) in reality. Do you understand now my scepticism how the JSX will perform with 2 people on board?
     

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