Самолётик сделан в 59 году - возможности были другие. Несмотря на непритязательный вид вес конструкции 55 кило и складывается за 5 минут. Крыло запатентовано в 74. В 83 ещё летал. SailWing серьёзно занималась NACA. На взлёте оно кривое и у него приличный коэффициент подъемной силы без всякой механизации. На крейсерском режиме малое сопротивление.
Кстати у Zenair Zipper такое крыло
www.youtube.com/watch?v=Y1jOlp_W5Uk
Вот один из заграницы собрался делать...
Well I have read a half dozen reports from Hiller, NASA, Princeton and the Military on the Princeton Sailwing. All very very informative and if you are interested in a ultralight with this type of wing you should definitely read them. There are a lot of misconceptions associated with this wing and its performance, these reports will take care of those.
After reading all these reports, looking at their data, and understanding what I was reading........this is a really good light aircraft wing. If you are not in a hurry, not wanting to use alot of hp, and somewhat simple folding for trailering after a day of flying. This wing fits the bill.
Now the first misconception it that it is a lot lighter than a standard rigid wing, not true. The D tube leading edge first must be drooped, then made stiff enough to handle all the flight loads, I do mean all the flight loads. All the lift is transferred to it. The trailing edge cable is rigged to keep the sailcloth under a preset tension, but not too much to prevent the material from forming the airfoil and camber changes needed for changes in speed and angle of attack. The D tube is going to weight about 23 to 30 lbs depending on the gross weight of the ultralight. A example is the wing from my ePelican Ultralight or my Beaver RX, both wings weigh about 35 lbs each. Only saving a few pounds with the Sailwing.
The next misconception it that it is very draggy. Also not true. The sailwing was designed with a bridle system to keep the TE (trailing edge) wire straight, and also to be flown without the bridle system on the TE wire. The data shows with the bridle the wing has a better lift capacity at lower airspeed and lower angles of attach with a moderate L/D ratio too. Without the bridal assy it has less lift capacity at lower airspeed and angles of attack AOA but much higher lift capacity at higher AOA, better than with the bridal assy. The camber of the airfoil with get higher and deeper without the bridal assy because the TE wire
will deflect forward toward the spar allowing the camber to increase...pretty neat if you ask me.
Another misconception is airfoil reversion or loss of shape in turbulence and negative AOA......not true. The wing has been tested all the way from -10 to +20 AOA without deformation at all, only a bit of fabric wrinkling at the TE inboard at the wing root, less than .003% area. Also shows great resistance to any change in turbulence if flown at proper airspeed, just what the maneuvering speed for standard aircraft is for.
Final misconception is no place to mount ailerons.......well you don't need them. The studies show that the best way is to warp the TE wire from the tip 1/3 from the LE diagonally to the root TE. Control forces are low and very effective at all speeds. Better than the wing tested with ailerons and less complex and lighter.
The biggest reason I can find as to why this wing design never made it into standard Ultralight Production was because of too many misconceptions being broadcast-ed by people who did not know what they were talking about. It just scared people away. I went thru the same things when I flew gyro-copters every day. I had at least 3 people a day come up to me and try to tell me I would die in a gyro, they had lost friends in gyros......well when I asked their friends name all the sudden it became a friend of a friend.......yeah you know the story all BS.
I am working up a Zipper right now, belongs to Dennis Long. All new parts and I will be doing the test flights on it. When I get to that point I will let you guys know exactly how the sailwing flies, no BS involved.
David M.
