I'm resending this post as I never got the original post back to my server or it dumped it or something. If you already got it just hit delete. Larry Flesner +++++++++++++++++++++++++++++++++++++++++++++++
>At 06:56 AM 12/13/04 -0600, you wrote: >>1. That sucking sound you here from the upper surface of the wing is the >>plane pulling money from your wallet. >>2. "Sucking up" is a force only when you are complimenting someone. >>Here is a link to a scientific explanation of LIFT: >>Dick Hartwig >>_______________________________________ > > >Larry's theory of lift: That "sucking sound" you hear is your "pucker" muscles giving out a muffled YEEEEE HAAAAAA !!! > >On a more technical note, Bernoulli's law, as stated in "Elements of >Aeronautics" (Pope-Otis, dated 1941), as it applies to airfoils is this: >"In a streamline flow, the greater the speed of the air the less the pressure >of the air, and the less the speed of the air the greater the pressure." >I don't think this theory has changed much since then. > >The wing on the KR is not divided into top only or bottom only but is >acting as a single unit. As it slices through the air, the air that is directed >over the top of the wing must accelerate in order to reach the trail edge >at the same time as the air directed below the wing because the air over >the top has a greater distance to travel. As the speed of the "over-the-top" >air increases, it's pressure drops. Assuming the air on the bottom side of >the wing maintains it's static pressure (29.92 in/2 at sea level, 59degrees F) , >we now have a difference of pressure of X in/2 between the two surfaces. >So, is it sucked up on the top side or pressured up from the bottom side, >you decide. I conclude it has a "pulling force" on the top and a "pushing >force" on the bottom acting on a single unit, the wing. The wing, as a >single unit, is forced in the direction of the low pressure. There are of course >too many other variables to cover here such a wing shape, cord to span ratio, >, etc. but the basics remain the same. > >I won't go into "angle of attack" except to say that it has a direct effect on the >location where the greatest "low pressure" or "difference of pressure" is generated on the top surface of the wing. The greater the angle of attack, >the further forward the center of lift (greatest low pressure) is generated. The >less the angle of attack, the further to the rear the center of lift is located. >This directly affects the "balance" of the airplane in the air and requires >the elevator forces to change to compensate for the changing center >of lift. > >When flying my KR, as the speed picks up in cruise, the wing develops >more and more lift. With the center of lift behind the C.G., the nose wants >to pitch down as the speed increases and the amount of lift increases. >Believe me, this change is considerable. I once demonstrated it to a >friend by taking off with the trim set at neutral, accelerating to cruise, >and as I passed him in the air I released the stick. I pulled negative >G's and scared the s#%*t out of myself. I had been holding considerable >back pressure on the stick to compensate for the increased lift being >generated behind the C.of G. If I slow to say 120mph, >the amount of lift ( behind the C.G. ) decreases and the nose of the >airplane tends to rise and the amount of back pressure on the stick >or trim required to hold the nose up is much less. > >This can >also lead to a problem when the C.G. is too far to the rear. As the >airplane slows in flight, you continue to increase the angle of attack >to maintain altitude. The center of lift continues to move forward on >the wing to a point forward of the C.G. and you could possibly run >out of enough elevator authority to lower the nose and continue >safe flight. > >Conclusion: The theory of lift is accurate regardless how you interpret >it. I'd suggest that those of you that have not yet completed you project, >get back to the shop and do so with complete assurance that if built to >plans, or somewhere close, that it will actually fly when completed! >You too will then be overwhelmed with the feeling that can only be >expressed with a giant YEEEEEEE HAAAAAAAA . > >Larry Flesner 112.5 hours and still grinnin' >
