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#21
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Bill Daniels wrote:
Denis, you should read up on the French designer Charles Fauvell and his flying wings. They flew pretty well although I think Jim Marske's designs are showing higher performance. Tailless designs fly quite well and the performance really doesn't suffer. They would be perfect for small jet engine self launchers. Hi Bill Yes I know that Fauvel "ailes volantes" like the glider AV36, and other flying wings like Horten's fly quite well. But I still doubt that suppressing the tail means suppressing the trim drag of an airplane. Flying wings have to use stable wing profiles (with positive pitching moment) and these produce more extra drag than a tailplane. Things are not so simple... -- Denis R. Parce que ça rompt le cours normal de la conversation !!! Q. Pourquoi ne faut-il pas répondre au-dessus de la question ? |
#22
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#23
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Andreas Maurer wrote:
On 14 Jan 2004 20:15:24 -0700, (Mark James Boyd) wrote: Just imagine what forces your movable weight will exert under a g load different than 1? For example, when you are flying through a vertical gust? I'd imagine it will behave the same as an attached one pound ballast weight on the upper part of the rudder of the glider used to balance the rudder. Perhaps I'm missing your point here... This is precisely the cause why your idea cannot work - and why the pilot of a hang glider is hanging so far *below* his wing. Now this a very interesting point. Whether the weight is above or below the C.G. seems to also have an effect. Thank you Andreas... The biggest safety feature would be ensuring the weight didn't come loose during a critical phase of flight (near the ground) and your supplementary "weight" cables don't hinder the original controls in any way... A weight right in the tail which moves maybe 3 feet forward when the auxiliary stick is moved might do it. Hmmm... Have you ever thought about what is regarded as the most important invention of the Wright brothers? You name it - aerodynamical control around all three axes. It seems this weight shift idea is just a very fine refinement. It's intention is to reduce that tiny bit of additional drag caused by moving surfaces or trim. I agree this is not anywhere near "the most important invention," but just a fun winter mind-teaser. There's a good cause why there was never such a system that ever worked on an aircraft, although thousands of designers have tried it in the pas 120 years. Well, it has worked to improve the efficiency in cruise of modern jet airliners, and has helped my fuel efficiency in my 172 across the country, but perhaps, as you point out, not as a primary control (for pitch in these cases). Except for ultralights and powered parachutes (which have a low hanging weight) we don't see it used in modern aircraft. Perhaps you are right, the standard glider design (with no low hanging weight) doesn't lend itself well to this means of control... Andreas Thanks for your thoughts! Mark |
#24
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Bill Daniels wrote:
Denis, you should read up on the French designer Charles Fauvell and his flying wings. They flew pretty well although I think Jim Marske's designs are showing higher performance. Tailless designs fly quite well and the performance really doesn't suffer. They would be perfect for small jet engine self launchers. Bill Daniels There are some obvious reasons not to use a canard (towrope tangling, landout damage, creates turbulence before the wing) but this seems an option as well... I've only flown one canard aircraft, (and never a flying wing) so I may delve into this more... |
#25
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#26
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#28
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Mark Boyd wrote:
Hmmm...anyone have data about forces provided by the elevator is flight?=20 For the lift on the tail of an LS7 (standard class), see the last column = of the table below. In a nutshell, in very slow flight the tail provides = about 8 kgf (18 pounds) upward force, and at VNE, about 60 kgf (130 = pounds) downward force. These numbers are approximate, as the major influence is caused by the = main wing pitching moment, which I estimated using xfoil and a single = section approximation of the wing profile. Francisco de Almeida "C1" and "7" IDA [33.3 daN/m2] =20 Flight param @ min weight =20 Wing =20 for "111-1024" =20 Drag =20 =20 =20 =20 Horizontal tail =20 =20 LD s Drag IDA Power V =20 Pd Rewing CLW a CdW CmW Cdi LD profile induced parasite Drag s M CLH LH =20 - ms-1 N kW kmh-1 ms-1 Pa - - deg - - - - N N N N ms-1 Nm - N =20 23.9 0.84 144 2.9 72 20.1 247 921,632 1.346 7.5 0.0200 -0.116 0.0270 26 48 65 9 122 0.76 -279 0.30 78 =20 32.7 0.68 106 2.3 80 22.2 302 1,019,787 1.100 5.3 0.0090 -0.110 0.0180 36 26 53 11 91 0.62 -324 0.21 67 =20 39.7 0.63 87 2.2 90 25.0 383 1,147,260 0.869 3.4 0.0070 -0.105 0.0112 39 26 42 15 82 0.64 -391 0.13 50 =20 41.5 0.67 83 2.3 100 27.8 473 1,274,734 0.704 2.0 0.0059 -0.101 0.0074 41 27 34 18 79 0.68 -464 0.06 32 =20 40.2 0.76 86 2.6 110 30.6 572 1,402,207 0.582 1.0 0.0056 -0.099 0.0050 40 31 28 22 81 0.77 -551 0.02 10 =20 38.3 0.87 90 3.0 120 33.3 681 1,529,680 0.489 0.3 0.0054 -0.097 0.0036 38 36 24 26 85 0.88 -642 -0.02 -13 =20 35.4 1.02 98 3.5 130 36.1 799 1,657,154 0.416 -0.3 0.0051 -0.095 0.0026 36 40 20 30 90 1.01 -738 -0.04 -37 =20 33.0 1.18 105 4.1 140 38.9 926 1,784,627 0.359 -0.8 0.0049 -0.093 0.0019 33 44 17 35 97 1.16 -838 -0.06 -62 =20 30.6 1.36 113 4.7 150 41.7 1063 1,912,100 0.313 -1.2 0.0050 -0.092 0.0015 30 52 15 40 107 1.38 -952 -0.08 -90 =20 28.0 1.59 124 5.5 160 44.4 1210 2,039,574 0.275 -1.5 0.0050 -0.091 0.0011 27 59 13 46 118 1.62 -1071 -0.10 -120 =20 24.9 1.9 139 6.6 170 47.2 1366 2,167,047 0.244 -1.7 0.0053 -0.090 0.0009 24 70 12 52 134 1.95 -1196 -0.11 -151 =20 20.1 2.49 172 8.6 180 50.0 1531 2,294,521 0.217 -2.0 0.0057 -0.089 0.0007 21 84 10 58 153 2.36 -1326 -0.12 -184 =20 17.7 2.98 195 10.3 190 52.8 1706 2,421,994 0.195 -2.2 0.0057 -0.088 0.0006 19 95 9 65 169 2.75 -1461 -0.12 -218 =20 =20 =20 =20 200 55.6 1890 2,549,467 0.176 -2.3 0.0057 -0.088 0.0005 17 106 8 72 186 3.19 -1619 -0.13 -257 =20 =20 =20 =20 210 58.3 2084 2,676,941 0.160 -2.4 0.0075 -0.088 0.0004 14 152 8 79 239 4.31 -1785 -0.14 -298 =20 =20 =20 =20 220 61.1 2287 2,804,414 0.145 -2.6 0.0090 -0.087 0.0003 11 200 7 87 294 5.55 -1936 -0.14 -336 =20 =20 =20 =20 250 69.4 2954 3,186,834 0.113 -2.8 0.0090 -0.086 0.0002 9 259 5 112 376 8.07 -2472 -0.15 -470 =20 =20 =20 =20 270 75.0 3445 3,441,781 0.097 -3.0 0.0089 -0.085 0.0001 7 298 5 131 =20 =20 -2849 -0.16 -565 =20 |
#29
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Andreas Maurer writes:
This is the cause why you need something aerodynamical to control your pitch, and why weight shifting does not work. Remember, with weight-shift control, if you are weightless, you are out of control. That's why it gets very "interesting" in a hang glider whenever you go weightless. Steve |
#30
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On Mon, 19 Jan 2004 17:51:30 +0000 (UTC), "Roy"
wrote: Twaddle ! There are guys who fly HG inverted (they are complete nutters, but the point is, it can be done) I'm talking about a *sustained* inverted flight, not a 4g loop where the inverted part takes one second. The loops you describe can also be done with a paraglider (where inverted flight is obviously a little... problematic). Bye Andreas |
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