各种扑翼机设计
<div class="section"><h2>1. The bird wing, the ideal</h2>
<p>Naturally, the great archetype for technical flapping wings is the living bird wing. His great effectiveness due to his manifold possibilities to move purposeful and to change the shape will certainly be unobtainable in aero modelling for a long time. This is also true for his weight distribution and his sensor technology.</p>
<p> <br/></p>
<p> </p>
<div style="TEXT-ALIGN: center; MARGIN-BOTTOM: 6px" class="gallery"> </div>
<p style="PADDING-BOTTOM: 10px; CLEAR: both">In this drawing by K. Herzog the anatomic subdivision of the bird's wing in arm- and hand section is pictured. It can also to be used advantageously when describing technical flapping wings. The longitudinal parts of these wing sections are rather different depending on bird species. Generally the bionics of the bird wing is very interesting <span class="small">(please take a look at external link 1)</span>.</p></div>
<hr class="wide"/>
<div class="section"><a name="membrane"></a>
<h2>2. Membrane flapping wings </h2>
<h4>Application range </h4>
<p>Membrane flapping wings especially are changing the chamber direction in the hand wing section according to the flapping direction. This way, they can produce much thrust and achieve steep climbing flights (Flying with Thrust). But up to now they are less suited for gliding flights and for flying with lift.</p></div>
<hr/>
<div class="gallery"><a name="sail"></a>
<h5>2.1 The sail as archetype</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/segel.gif"></a> </div>
<div style="MARGIN-TOP: 6px" class="img-column"><br/> </div>
<p>A sail - though in other circumstances - has about the same function as a flapping wing. It shall generate as much thrust as possible under changing approach flow directions.</p>
<p>By material selection, layout, division into parts, sail trim and rig tuning the sail characteristics can vary in wide ranges. Battens give the sail more stability and an optimal shape. A lot of descriptions with sophisticated tips about the fabrication of the sail and its practical use can be found.</p>
<p>Indeed, a lot of membrane flapping wing systems have been developed, but detailed information about them is barely available.</p></div>
<hr/>
<div class="gallery"><a name="simple"></a>
<h5>2.2 Simple membrane flapping wings</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/english/images/wings/pinion.gif"></a><br/>The <strong><q>pinion feather</q></strong> by <img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> Alexander Lippisch (ca 1937) obviously was optimized for thrust generation. Therefore, he increased the chord in the outer wing area. But this pinion feather was not intended for generating lift at the same time. It's merely a propeller for changing rotation directions.</div></div>
<div class="gallery">
<div style="MARGIN-TOP: 0px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/membrane.gif"></a><br/> </div>
<p style="MARGIN-TOP: 32px"><q>Tim</q> was the first in mass-produced rubber powered flapping wing model - with simple membrane flapping wings - invented by Albertini Prosper and de Ruymbeke Gérard (France 1969).</p></div>
<div class="gallery">
<div class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/tim_bird.jpg"></a> <br/></div>
<p style="MARGIN-TOP: 6px">The membrane printing of Tim in the marginal picture was drafted by <img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> K. Herzog.<br/>Under the designation <strong><q>Tim Bird</q></strong> this model is available in trade till today.</p></div>
<hr/>
<div class="gallery"><a name="battens"></a>
<div style="MARGIN-TOP: 12px" class="img-column"><a href="http://www.ornithopter.de/grafik/prinzip/penaud.gif"></a><br/>2.3 Simple membrane flapping wing<br/><span style="MARGIN-LEFT: 1.6em">with battens</span></div>
<p>Here a famous Membrane Flapping Wing, equipped with small <q>battens</q> for stabilisation of the membran, developed by A. Pénaud (France 1872) <br/><span class="small">(more informations at external link 2</span>). </p></div>
<hr/>
<div class="gallery"><a name="active"></a>
<h5>2.4 Active twisting by spar rotation </h5>
<div style="MARGIN-TOP: 6px" class="img-column"><br/></div>
<div style="MARGIN-TOP: 6px" class="img-column">Membrane flapping wing by Erich v. Holst (1943) with drive-controlled wing twisting in the arm wing section by spar rotation. Only the rib at the end of the arm wing (number 9) is fixed to the spar. It is linked with a crank drive which effects the stroke movement as well as the rotary movement of the spar.</div></div>
<div class="gallery">
<div class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/vogelmodell.gif"></a><br/>The twisting in the hand wing section happens largely passively. In addition, a transition from cross to longitudinal battens can be seen. In spite of alternating profile chamber direction during a flapping cycle a relatively purposeful increase of wing twisting tipwards is made possible.</div>
<p>The bird models by K. Herzog (1963) follow this scheme, too.</p></div>
<hr/>
<a name="torsion"></a>
<h5 class="gallery">2.5 Aeroelastically twisting by spar torsion</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/pressluft.jpg"></a> <br/></div>
<p style="PADDING-BOTTOM: 0px" class="gallery">The flapping wing model of the Czech Cenek Chalupsky (1934) was flying steadily without a tail unit. Its achieved climb power is still considered remarkable toda</p>
<p>.weight</p>
<p>.wing span</p>
<p>.cane spar </p>
<p>.covering</p>
<p>.ceiling </p>
<p>.3.1 kg</p>
<p>.2 m</p>
<p>. </p>
<p>.linen</p>
<p>.10-15m</p>
<p>.</p>
<p>.</p>
<p>. </p>
<p>.</p>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/holmtorsion.gif"></a><br/>Each flapping wing of this ornithopter has two spars. The straight, bending resistant spar (H1) transmits the power of the stroke motion. The bended torsion elastic spar (H2) determines the magnitude of the wing twisting.</div>
<p>Both spars cross approximately in the center of the half span. At the crosspoint they are movably interlinked. For the torsion elastic spar (H2) not to bent backward too much a string or an elastic thread is apparently tightened between the tips of the spars.</p>
<p>During downstroke of the wings the lifting forces are increased. The spar H2 and the wing are twisting. The magnitude of the twisting acts in accordance with the magnitude of the lift force and the stiffness of the spar. It therefore happens aeroelastically.</p>
<p>Additionally to the twisting the tip of the spar H2 bends upwards during downstroke. As a reaction it bends downwards at the other side of the crosspoint - thus, in the section of the arm wing. Thereby, the camber of the airfoil is increased a little. Thereby, an adaptation to the requirements of an effective stroke motion takes place.</p>
<p><span class="small">Please look at <img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> Piskorsch Adolf (1975): <q>Pressluft-Schwingenflugmodell Chalupsky</q> and the vidio of the<br/>external link 3</span>.</p></div>
<hr/>
<div class="gallery"><a name="oiseau"></a>
<h5>2.6 Flying wing ornithopter</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/oiseau.jpg"></a><br/></div>
<div style="MARGIN-TOP: 6px" class="img-column"><br/> </div>
<p>Ornithopter without a tail unit, developed by Jean-Louis Solignac (France, 2000).</p>
<p>The flapping wing model has a very simple and light driving mechanism and is powered by a rubber drive. With a wing span of 15 cm (5.9 in) it has a weight of only 0.6 gramms (0.021 oz ). The airplane performances are amazingly good (<span class="small">for the construction of the flapping wing model please also take a look at external link 4.)</span></p>
<p>The particular about this flapping wings is the down cambered airfoil shaped by battens. Thereby it flies in a stable attitude without a tail unit. This can theoretically be explained with the shifting of the pressure point of thin airfoils. It can be tested in the adjacent experiment with a paper airplane. The cross-section of this paper airplane equates to a down chambered airfoil.</p>
<p style="MARGIN-TOP: 32px">If you keep the center of gravity at the same distance <q>d</q> form the leading edge like at the paper airplane, also a lightweight flying wing glider made of balsa is flying perfectly.</p></div>
<hr/>
<div class="gallery"><a name="tandem"></a>
<h5>2.7 In tandem </h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/holst_libelle.gif"></a><br/>Ornithopter with two sets of flapping wings based on a dragonfly, developed by Erich von Holst (1943).</div>
<p style="PADDING-BOTTOM: 0px">Here, for simplifying the mechanism both opposite halves of a wing are rigidly fixed to a unit. This way, the pressure point of the model is fixed between the two wing units.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/tandem.jpg"></a><br/>In such tandem arrangements with wings flapping in opposite directions the vertical pendulousness of the fuselage should be avoided. This, however, bears the disadvantage that the backmost flapping wing is in the turbulence wake of the front one. Only for very small wings and at very small Reynold's numbers this may be beneficial.</div>
<p>Model by Horst H?ndler (1988).</p></div>
<hr/>
<div class="gallery"><a name="thrust"></a>
<div style="PADDING-TOP: 12px" class="img-column"><br/><a href="http://www.ornithopter.de/english/images/wings/thrust_wing.jpg"></a><br/> </div>
<h5>2.8 Thrust-wing</h5>
<p>By mechanisation of a dragonfly's flight principle<br/><img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> Erich von Holst has developed his thrust-wing model with two in the opposite direction rotating three-blade wings (1940). The flapping angle in one stroke direction constitutes 180° or 360° for a complete flapping cycle <span class="small">(please take a look to the video at external link 5</span>).</p>
<p>Three instead of two wing blades per rotor offer a constant supporting force (<span class="small">see also configuration of the rubber powered model ENTOID by Velko T. Velkov (2007) external link 6)</span>.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/english/images/wings/thrust_lift.gif"></a><br/>In contrast to a propeller a lift force perpendicular to the thrust is generated at the thrust-wing, too. One must only increase the <q>thrust-wing advance ratio</q> (v/u) - similar to a flapping wing - and fly with a positive angle of attack of the thrust-wing axis.</div>
<p>This is a fine example for an innovative transfer biological principles of a flapping wing in engineering. But the specialism <q>bionics</q> did not exist at that time.</p></div>
<hr/>
<div class="gallery"><a name="stretched"></a>
<h5>2.9 Oscillating stretched wing</h5>
<p>Thrust also can be produced by raising and lowering a stretched wing in flight. But thereto the lift or the transverse force during the upward motion must be smaller than during downward motion. The bigger the difference, the better for the thrust <span class="small">(please take a look to the principle of flight/vector diagram)</span>. Furthermore, a continual alignment of the angle of incidence is normally necessary.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/oszillierend.gif"></a><br/>Here a strikingly simple generation of an accordant oscillating motion of the wing by using an eccentrically pivoted rotating mass consisting of the mainspring and the gear. In this case the wing is aeroelastically twistable. The idea was coined by W. B. Mituritscha (probably from Russia, 1953).</div>
<p>Unfortunately, a forward and backward motion of the wing occurs along the way. However, this can be avoided by a second counterrotating mass.</p>
<p>There are diverse proposals to generate an oscillation motion of the wing by a pilot who is flying in a hang-glider or an other ultralight aircraft - for example by fast press-ups or knee-bends. </p>
<p style="MARGIN-TOP: 8px">Entirely different model experiments with oscillating wings shows Karl-Heinz-Helling with his <q>Double flapping wing airplane</q> (2008) <span class="small">external link 7</span>.</p></div>
<hr/>
<div class="gallery"><a name="rotated"></a>
<div class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/rotationsflugel.gif"></a><br/>2.10 Rotating wings </div>
<p>To avoid the accelerating forces at the final stroke positions <q>flapping wings</q> rotating on a cone-shaped shell where sometimes built whose apex lies at the wingroot.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 0px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/rotorlibelle.jpg"></a> <br/></div>
<p style="MARGIN-TOP: 32px">Examples: <br/>The <q>Rotor Dragonfly</q> (1944 and 1989) by<br/><img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> Adolf Piskorsch</p>
<p>and</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 0px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/rotierend.jpg"></a><br/>the flight model by Horst H?ndler (1989).</div>
<p>Both ends of the driveshaft are bended in Horst H?ndler's model. Thereon, the wings are attached freely twistable. The angles of incidence is guided by the upward pointing levers on the wings.</p></div>
<hr/>
<div class="gallery"><a name="none"></a>
<h5>2.11 With non-twistable arm wing section</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/spencer_seagull.jpg"></a><br/>Membrane flapping wing with a non-twistable arm wing section and passive twisting at hand wing section.</div>
<p>The arm wing is triangle shaped and has a large wing depth at the wing root. Arm- and hand wing membrane overlap in wing span direction. Obviously, the hand wing spar could make a little flap movement at the wrist. Later the hand wing depth was enlarged <span class="small">(Please also take a look at the construction of the <q>pinion feather</q> by Alexander Lippisch)</span>.</p>
<p style="PADDING-BOTTOM: 0px">This daedalean flapping wing design of the <q>Seagull</q> was developed by Percival H. Spencer (USA 1958) <br/>(<span class="small">please take a look at external link 8</span>).</p></div>
<div style="PADDING-BOTTOM: 8px" class="gallery">
<div style="MARGIN-TOP: 0px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/segellatten.jpg"></a><br/>Today, this design principle of flapping wings with inserted battens is widely-used.</div></div>
<hr class="wide"/>
<div class="section"><a name="profile"></a>
<h2>3. Profiled flapping wings</h2>
<h4>Application range</h4>
<p>Profiled flapping wings or double-sided covered wings may work with a very high efficiency. With their mostly relatively low flapping frequency and the small operating range of lift coefficient of a simple airfoil not much thrust can be produced. Not, at least, if the full lift must be generated concurrently (flying with lift). Therefore, profiled flapping wings are suited especially for a level flight, the gently inclined climbing flight and of course for changing to gliding flight.</p></div>
<hr/>
<div class="gallery"><a name="feathers"></a>
<h5>3.1 With artificial feathers</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/w_filter.gif"></a> <br/><a href="http://www.ornithopter.de/grafik/fluegel/gestaffelt.jpg"></a> <br/></div>
<p>To ease the twisting, the closed airfoil can be faned out. So far, this is particularly used for large manned ornithopters.</p>
<p>Adjacent, a flapping wing with staggered wing tips of the manned <q>Schwan 1</q>, developed by Walther Filter (1955, at the Hannover fair 1958). The angle of incidence deflection of the <q>feathers</q> designed as several wings was controllable <span>(please also take a look at external link 9)</span>.</p>
<p>Even for splay and straddle movement of the <q>feathers</q> there are old design proposals. In contrast, with <span class="evtyp">EV7b</span> only with simple feather implementations experiments have been made.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 2px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/federn.gif"></a><br/>A further example for artificial feathers is the <q>Ikarus</q> by Emiel Hartman (England 1959).</div>
<p>More recent experiments with artificial feathers are to be seen </p>
<ul style="LIST-STYLE-TYPE: disc">
<li>at gliders with out-faned wing tips <br/>by Johannes Huser, </li>
<li>at the <q>Birdman</q> Georges Fraisé (France 2005) and</li>
<li>at the Ornithopter Project by Ryszard Szczepa?ski (Poland 2002). </li></ul>
<p class="small">(please look at external links 10, 11 and 12)</p></div>
<hr/>
<div class="gallery"><a name="inclined"></a>
<h5>3.2 With inclined hinge of the hand wing</h5>
<p>A special version of a flapping wing derives from K. Herzog (1963). With this wing, the rotation or the twist axis, is not standing vertical to the stroke axis.</p>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/schlagfluegel.gif"></a><br/>The arm wing should perform a flapping motion and a twisting motion at the shoulder joint. With rubber threads between arm- and handwing the latter was pulled down a little (aeroelastically wing).</div>
<p>This is also an early suggestion for an articulated flapping wing with an additional flap movement of the hand wing.</p>
<p>The kink of the profile between the arm and the hand wing lies approximately at the same location as on the above-mentioned membrane wing by P. H. Spencer.</p></div>
<hr/>
<div class="gallery"><a name="tilt"></a>
<div class="img-column"><a href="http://www.ornithopter.de/english/images/wings/cycle.gif"></a><br/>3.3 Twisting by tilting the leading edge<br/><span style="MARGIN-LEFT: 1.6em">of the wing</span></div>
<p>The feature of the <q>pitch propeller</q> by John Drake lies in the twisting of the leading edge, not the trailing edge of the flapping wing (England, flight tests in 1978).</p></div>
<hr/>
<div class="gallery"><a name="stepped"></a>
<h5>3.4 With stepped twisting</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/stufig_ev4.jpg"></a><br/>An approximate wing twisting can also be achieved by a stepped rotation of relative non-twistable wing sections.</div>
<p>The model <span class="evtyp">EV4</span> (1979) was also equipped with such a rotation of single wing sections. But in this case, the rotations was controlled by the wing drive.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/stepped.jpg"></a><br/>A typical representative of a passive stepped twisted wing is the <q>Step-Twister</q> with his foam wings (Depron) by Karel Pustka (2004). The developing gap between the wing sections is covered with a membrane.</div></div>
<hr/>
<div class="gallery"><a name="auxiliary"></a>
<div style="PADDING-TOP: 12px" class="img-column"><br/>3.5 Twisting by stroke movement<br/><span style="MARGIN-LEFT: 1.6em">of the auxiliary spar</span></div>
<p>Here, the wing twisting is generated by a phase-delayed stroke movement of the main and auxiliary spar - developed by Emile R?uber (France 1909).</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/hilfsholm.jpg"></a><br/>This technology was also used at the <span class="evtyp">EV2</span> (1976). In the margin, the wings with their two spars powered separately are to be seen.</div>
<p style="PADDING-BOTTOM: 0px">The function is similar to the wing of a dragonfly. Here, too, the phase-delayed flapping movement of the main and auxiliary spar determines the amount of the wing twisting.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/english/images/wings/dragonfly.jpg"></a><br/>
<p class="smaller">(dragonfly picture: 300 KB)</p></div>
<p style="MARGIN-TOP: 8px">Furthermore, the dragonfly obviously works with a strong spar at the leading edge. With the phase-delayed flapping movement of three spars the camber of the airfoil can be influenced, too.</p>
<p>The supports or linkages of the three spars at the body are clearly recognizable as dark, partly crossing structures at the back of the dragonfly (<span class="small">please also take a look to external link 13 and 14</span>).</p></div>
<hr/>
<div class="gallery"><a name="maccready"></a>
<h5>3.6 Servo controlled wing twisting</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/maccready.jpg"></a><br/>This is a lifelike and airworthy replica of a pterosaurs - a Quetzalcoatlus Northropi (QN). <br/>The aerodynamics of this ornithopter should fully equate the original. The idea come from the creative genius Dr. Paul MacCready (USA 1985).</div>
<p>The twisting of the wings was controlled by servos and the flight attitude was stabilized by backward and forward motions of the wing tips and nodding motions of the head.</p>
<p><span class="small">For details - including the principle of the drive mechanism - please take a look to the articles (in German) about the project by <img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> Paul MacCready and for further informations via external link 15</span>.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/smartbird.jpg"></a><br/><br/><br/><br/></div>
<p>Also at <q>SmartBird</q> by the company Festo the twisting of each wing side is controlled by a servo (2011). However, in this case only the twisting of the hand section of the wing is controllable. The inner arm section is not twistable. Its wing span is 2.0 meter.</p>
<p>The wing covering is made of a 2 mm extruded Polyurethan foam plate which is formed to an airfoil (the cross section of the wing used at the model differs from the here shown wing ribs). Upper and lower side of this covering are not glued together at the rear end. So they can slide against each other and the wing is able to do twisting motion without folds (please take a look at the Shearflex principle in the next section). </p>
<p style="MARGIN-TOP: 16px">At SmartBird it is noticeable that the wing mechanism imitates the bending between arm and hand section of bird wings. The accompanying images show a basic structure of the flapping wing mechanism during up und down stroke. You also can seen an animation <span class="smaller">(2.1 MB)</span> of it.</p>
<p style="MARGIN-TOP: 16px" class="smaller">For further details about the SmartBird project please take a look at external link 16.</p></div>
<hr/>
<div class="gallery"><a name="shearflexed"></a>
<h5>3.7 Shearflex principle</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><br/></div>
<div style="MARGIN-TOP: 6px" class="img-column"><br/><br/> </div>
<p>Here an aeroelastically twistable profiled flapping wing according to the <strong>Shearflex Principle</strong>. This system makes a relatively inelastic covering applicable. If the twisting along the wing is constant and not to excessive, the airfoil contour accuracy is therefore very good.</p>
<p>Here, the twist elasticity will mainly be determinated by the spar designed as wing leading edge.<br/>This system was invented by Professor <img title="literature" alt="literature" src="http://www.ornithopter.de/grafik/allgem/literatur.gif" width="15" height="18"/> James D. DeLaurier and Jeremy M. Harris (Canada 1994).</p>
<p>The ornithopter with its tripartition of the flapping wing is interesting, too. Jeremy M. Harris 1977 has applied it for patent.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 0px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/delaurier_harris.jpg"></a><br/>On the adjacent photo James D. DeLaurier and Jeremy M. Harris can be seen with their remote-controlled model, 3 m in span and with combustion motor. A sustained flight was achieved 1991. A video is available (<span class="small">please take a look at external link 17</span>).</div></div>
<div class="gallery">
<div class="img-column"><br/><a href="http://www.ornithopter.de/grafik/fluegel/haendler_del06.jpg"></a> <br/></div>
<p style="PADDING-TOP: 72px">Here, a corresponding replica with an electrical drive system by Horst H?ndler (1994).</p></div>
<hr/>
<div class="gallery"><a name="oscillating"></a>
<h5>3.8 Oscillating wing tips</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><br/><br/><a href="http://www.ornithopter.de/grafik/fluegel/snowbird.jpg"></a><br/> </div>
<p style="PADDING-BOTTOM: 4px">The main spar of the <q>Snowbird</q> has no hinge, and instead flexes to produce the desired flapping motion. By this way the wing tips perform an oscillating motion. Thereby the wing twists passively under aerodynamic loads.</p>
<p>The principle of a wire powered wing oscillation has some marked advantages particularly for man powered ornithopters:</p>
<ul style="LIST-STYLE-TYPE: disc; MARGIN-BOTTOM: 0px; MARGIN-LEFT: 196px">
<li style="LINE-HEIGHT: 1.3">fail-safe wing position for gliding</li>
<li style="LINE-HEIGHT: 1.3">applicable for large wing spans with its accordingly low induced drag</li>
<li style="LINE-HEIGHT: 1.3">very few moving parts</li></ul>
<p>Todd Reichert has played an important role in developing of the Snowbird and he also has flown it successfully (Canada 2010). <br/><span class="small">For more informations about the Human-Powered Ornithopter (HPO) Project "Snowbird" please take a look at external link 18.</span> </p></div>
<hr/>
<div class="gallery"><a name="shell"></a>
<h5>3.9 Shell wing</h5>
<div style="MARGIN-TOP: 6px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/aktive.gif"></a><br/>with active wing twisting by a drive controlled spar rotation, developed by Albert Kempf (France 1998, <span class="small">please take a look at external link 19</span>).</div>
<p>Apparently, the upper side of the wing consists of a cambered hard shell, which is shaped with foam on the lower side to a profiled airfoil wing.</p>
<p style="PADDING-BOTTOM: 0px">A long thin plate with a cambered cross section may be twisted easily and creaselessly. Also the aforesaid shearflexed wing is using this property. This flapping wing category here is called <q>shell wing</q>.</p></div>
<div class="gallery">
<div style="MARGIN-TOP: 0px" class="img-column"><a href="http://www.ornithopter.de/grafik/fluegel/truefly.jpg"></a><br/>The such equipped <q>Truefly</q> is to be seen in the adjacent picture - an ornithopter with a wonderful flying sight. It also was the first ornithopter which achieved strong climbing flights with profiled flapping wings.</div></div>
<hr/>
<div style="MARGIN-TOP: 16px" class="section">
<p>In the essay <span class="download"><q>Flapping Wing Designs</q></span> <span class="smaller">(in German, PDF 1.8 MB, version 2.3, 2008)</span> additional information about these flapping wing designs can be found.</p>
<p>In conjunction with the <span class="evtyp">EV</span>-models developed flapping wings are to find on site: <q>Articulated flapping wings</q></p>
<p><q></q> </p>
<p><q></q> </p><q>
<h2>原文地址：<font face="Verdana"><a href="http://www.ornithopter.de/english/wings.htm">http://www.ornithopter.de/english/wings.htm</a></font></h2></q></div>
[此贴子已经被作者于2012-6-17 17:23:04编辑过]
支持楼主 <p>顶楼主</p> 太帅了，支持！！！ ]比较详细 好东西 顶楼主！！ <p>楼主见过对拍扑翼吗，而且机翼是两自由度的，沉浮的同时还要扭转。谢了！</p> 我在研究载人的，努力中。谢楼主 先顶一个
页:
[1]
2