Place your bets - Will it fly (back)? :)

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earth_bound_misfit

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Takao Doi is to test if a Boomerang to see whether or not it returns without gravity. I suspect it has more to do with aerodynamcs than gravity.<br /><br /> New.com.au <br /><br />A JAPANESE astronaut plans to throw a boomerang inside a space station to test how it can fly in zero gravity.<br /><br />Astronaut Takao Doi, 53, is set to travel on a US shuttle in March to the International Space Station, where he will be in charge of construction of a Japanese scientific testing room.<br /><br />It is believed gravity is needed for a boomerang to fly back to the throwing spot, but no one has tried in zero gravity.<br /><br />"Mr Doi said he will personally carry a paper boomerang for the upcoming mission and we presume he will try it when he has spare time,'' said an official of the Japan Aerospace Exploration Agency.<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>
 
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earth_bound_misfit

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<span method="POST" action="/dopoll.php"></span> <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>
 
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earth_bound_misfit

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I guess it will have to be a very small Boomerang, anyone who's thrown one before will know you need a lot of space. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>
 
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siarad

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Yes sawed some from plywood when young, so no aerodynamics therefore I'm assuming gravity made it fly a curved path. Took some practice to make it return having to aim it downwards & get the right spin
 
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heyscottie

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But clearly it must be aerodynamics. After all, a ball and a boomerang of the same mass would be acted upon the same by gravity. And yet a ball doesn't come back!<br /><br />I will say that absent of gravity, a boomerang would surely take a DIFFERENT path, since right now, the aerodynamic forces also counteract gravity. In short, I think the boomerang would suddenly have too much lift.
 
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kyle_baron

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I voted No. It will not fly back to the throwing spot. If that's what you mean by, will it fly? <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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earth_bound_misfit

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"If that's what you mean by, will it fly?"<br /><br />Yep, I wanted it to sound like Lettermans's "will it float", might change that. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>
 
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michaelmozina

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My guess is that won't fly back to it's original point because most boomerangs are designed to work like an airfoil. They work like a wing and produce upward lift to overcome the force of gravity. It won't come back to it's starting point because there is nothing to make it come back down again when it starts to spin and produce lift. It will continue to generate lift even when it's spin rate slows down due to friction with the air, although it will generate less lift. Since there is no gravity to make it come back down again, and to cause it to lose it's lift momentum, it's never going to return to it's point of origin. It's glide path will resemble an accelerating spiral shape until it stops rotating entirely and then it will simply continue along it's final path indefinitely.<br /><br />That's my opinion anyway. <br /><br />I also agree with ebm's point about needing a lot of space. I don't think you'd get the full effect by throwing it inside the ISS, and someone might get hurt. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>
 
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qso1

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If you mean will it return to the person tossing it...I voted no. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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Mee_n_Mac

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Let me be the contrarian of the group. A boomerang operates when spinning and as such is a gyro. The aero forces are unbalanced during a rotation and so you get a net torque and thus precession. This vectors the thrust from the boomerang which causes it to come back to the thrower. Without gravity to pull the 'rang down, it'll return to the sender too high if thrown normally. However throwing it differently might return it to the sender (ie - aim low). I think it <b>could</b> be done since the precession won't be affected by the micro G environment. The flight path will be different from that on Earth. How many throws does he get to practice ? <br /><br />EDIT : More precisely the aero forces from the blades don't act throught the CoG thus there's a net torque and thus precession. <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>
 
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Mee_n_Mac

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Would you agree that gravity can only account for the vertical motion of the gyro ? If so the semi-circular motion that returns the boomerang in the horizontal plane should remain. You only need to get the proper downward trajectory so the vertical lift, now not cancelled by gravity, returns the 'rang to it's throwing height. In fact you need not throw it "down" at all, just at the proper angle to it's rotational axis.<br /><br /><br />Thats fo sho, bro !<br /><br /> <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>
 
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schmack

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I'm with MnM, it'll come back provided its thrown at the correct angle. and it has an engineeringly correct weight at one end in order to distort its ariel rotation properly, it will definitely come back. <div class="Discussion_UserSignature"> <p><font size="4" color="#ff0000"><font size="2">Assumption is the mother of all stuff ups</font> </font></p><p><font size="4" color="#ff0000">Gimme some Schmack Schmack!</font></p> </div>
 
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centsworth_II

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<font color="yellow">"In fact you need not throw it "down" at all, just at the proper angle to it's <br />rotational axis."</font><br /><br />I don't know anything about boomerangs, so I looked it up: <br /><b>"A boomerang is always thrown overhand like a baseball. Never, ever throw your <br />boomerang side-arm. It will climb straight up in the air, then swoop back down..."</b><br />http://www.boomerangs.org/how.html <br /><br />It seems the "proper angle" is near 90 degrees on Earth or in the space station. <br />My guess is that the boomerang would have to be very lightweight -- like foam <br />plastic -- and small. To turn in a small space, it would have to be <b>very</b> light <br />(low inertia). The throwing motion would be like throwing a dart. Maybe thrown<br />at an angle down. The blades would be specially designed to accentuate <br />turning and minimize lift. It could be made to work.<br /><br /> <div class="Discussion_UserSignature"> </div>
 
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thebigcat

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I think that it will, space permitting, fly in a circular arc in a direction perpendicular to the boomerang's orientation at release, around to a full circle behind the thrower, with only the reduction in rotational velocity preventing it's course from describing a perfect circle.<br /><br />That's just my guess. <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>
 
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michaelmozina

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I don't think there's enough space to make this thing work in 3D. I can at least in theory agree with the idea that the right downward pitch during the toss might do the trick as it relates to overcoming the lift from the airfoil, so perhaps with enough practice it might actually come back to it's point of origin. It requires a great deal of space to make one of these babies really fly here on earth, and there isn't that kind of room up there. <br /><br />It's definitely an interesting question. <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>
 
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siarad

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Sorry no time to read whole topic in case I'm repeating<br /><blockquote><font class="small">In reply to:</font><hr /><p>But clearly it must be aerodynamics. After all, a ball and a boomerang of the same mass would be acted upon the same by gravity. And yet a ball doesn't come back! <p><hr /></p></p></blockquote><br />I meant it was 'flat plate'.<br />Yes such does give lift, most at 6 degees I recall.<br />The action is surely gyroscopic which would be modified by gravity not 'toppling' it <img src="/images/icons/smile.gif" /><br />
 
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centsworth_II

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<font color="yellow"><br />"The action is surely gyroscopic which would be modified <br />by gravity not 'toppling' it."</font><br /><br />Is it gravity that topples it, or does it just move to a<br />stable attitude through aerodynamic forces. <div class="Discussion_UserSignature"> </div>
 
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centsworth_II

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<font color="yellow">"I don't think there's enough space to make this thing work in 3D."</font><br /><br />What about the indoor boomerang I link to above with a 6 foot (2 meter) range? <br />And the news item I read said that the boomerang to be tested on the shuttle <br />will be made of paper -- not your typical boomerang.<br /> <div class="Discussion_UserSignature"> </div>
 
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Mee_n_Mac

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<font color="yellow">Is it gravity that topples it, or does it just move to a <br />stable attitude through aerodynamic forces. </font><br /><br />Gravity can not "topple" a gyro or a boomerang. That's the thing about gyros, they tend to keep pointing where they have been unless acted upon by a <b>torque</b>. Then they precess and "topple". Gravity will exert a force over the entire body of the boomerang, acting on all parts equally, and thus there's no net torque. It will cause translation of the body but no rotation (change in attitude).<br /><br />Mind you, I not going to go all "Randi" on this and put up any $$s on the outcome of the experiment. <img src="/images/icons/smile.gif" /> It'll be interesting to see the video. <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>
 
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centsworth_II

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<font color="#666699">"Mind you, I not going to go all "Randi" on this and put up any $$s on <br />the outcome of the experiment."<br /></font> <br />Wise choice -- unless you've got some inside information. I have a <br />feeling that even more important than the physics of the situation <br />will be the skill of the thrower. <div class="Discussion_UserSignature"> </div>
 
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h9c2

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The correct angle to throw a rang creates enough lift to compensate for gravity. In microgravity, or zero-g, the rang would spiral up if thrown as on earth (but it would more or less return). I think it will return to be caught only if thrown properly, ie at just about a 90 degree angle
 
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earth_bound_misfit

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"I think it will return to be caught only if thrown properly, ie at just about a 90 degree angle"<br /><br />My toy one (from when I was a kid) said to throw it at a two o'clock angle into the wind. <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>
 
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rogerinnh

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Many of these posts about the boomerang indicate a need to toss it at the correct angle. But angle to what? The person tossing it, the ground? How can that be relevant where there is no gravity? The "toss" of the boomerang inside the ISS can be thought of as starting it to spin and then pushing it in some direction. There is no "angle" in the toss, it's just pushed forward.<br /><br />The forward motion and the spinning then creates lift. Well, not lift, since that implies a direction opposite to the pull of gravity. Actually it creates a motion perpendicular to the center of rotation. So the forward motion plus the motion perpendicular to the rotation should create a curving trajectory. It should be somewhat like throwing one of those simple balsa-wood airplanes with the both elevators canted upwards the same amount so that the plane makes a simple up-over-your-head-and back-to-you-from behind loop.<br /><br />Whether or not it actually comes back precisely to the spot from which it was thrown will depend on the ratio of the slowing down of the forward motion to the slowing down of the rotational motion, since each such motion contributes to the "lift" as it moves. It may trace out a decreasing radius circle, an increasing radius circle, or just a circle. Only in that last case will it return to the starting point.
 
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rogerinnh

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It's also possible that the "advancing" side of the boomerang will have a bit more "lift" (force perpendicular to the rotation) than the "receding" side of the boomerang as it moves forward through the air. This would cause the boomerang to rotate around the line of its forward motion, thereby twisting its trajectory. Whether or not it returns to its point of origin would still depend on the ratios between the slowing of the forward motion and the slowing of the rotational motion, since the amount of twisting (and hence its effect on the trajectory) would also be dependednt on those two motions.
 
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