Stranga launch photo

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bovlk

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Hello,<br /><br />I looked at some pictures in the gallery and found this picture from the launc of Apollo 11<br />http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=2603&gid=204<br />What suprised me is the fact that the flames start not behind the jets, but even in front of them and seem to go from the bows of the rocket. Second, about twice the length of the rocket behind its end, a clearly new cone of flames starts. What causes this? Thanks in advance.
 
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vogon13

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I didn't check the picture, but keep in mind, as the rocket rises, the surrounding air pressure decreases and the plume from the engine expands considerably. From various angles on the ground, this expanding plume can certainly 'look funny'.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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CalliArcale

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If you happen upon some video footage of the entire launch, I highly recommend it. It's fascinating.<br /><br />During many launches (including of the Space Shuttle and other rockets), what looks like smoke or flame will seem to come out of the front of the vehicle. This is actually neither smoke nor flame (except in some unfortunate circumstances). It's a condensation cloud. The same thing happens to fighter jets going supersonic, and even in some subsonic aircraft. For instance, if conditions are right, you can see condensation clouds form over the wings of airliners on approach, or producing long, beautiful streamers coming out from either wingtips or, more commonly, the flaps. The wingtip and flap ones are actually forming in vortices, and sometimes you can even see the spinning motion in the streamer. It can be disturbing if you don't know what it is.<br /><br />Basically, it's a consequence of moist air being compressed in front of the vehicle. As the air expands and cools back down, water vapor condenses and forms a cloud. They can be very beautiful, and very strange. Watch for these clouds on the next Shuttle launch, if you have NASA TV access. It doesn't always happen (it depends on dew point and ambient temperature) but when it does, it can be very pretty. They'll form mostly around the noses of the ET, SRBs, and Orbiter. On the Saturn Vs, these clouds could form off of any protruberance -- the nose of the escape tower, the nose of the CM, the LM's housing, the conical transtages, and possibly even the tail fins (although it's awfully hot down at that end).<br /><br />The other thing you're seeing in this picture is what vogon13 already pointed out. As the rocket climbs, the air gets less dense and the plume expands considerably. It often changes color as well, because this affects combustion. Complicating the picture is that you actually aren't seeing the rocket from the side anymore. It's tipped away from the camera and thus foreshortened. (I <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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drwayne

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A note:<br /><br />In certain atmospheric and vehicle speed regimes, the shock layer at the aft of the vehicle detaches and moves fowards, and some of the exhaust gases (and soot in the case of stages such as the first stage of the Saturn 5 that are hydrocarbon fueled) can actually move foward on the vehicle, and at certain stages this "plume envelopment" can encompass the entire vehicle.<br /><br />A couple of effects that have to be accounted for are:<br /><br />(1) Increased external heating of the vehicle<br /><br />(2) Deposits of soot on surfaces.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
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drwayne

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I just looked back, one of my favorite sites refers to this sort of thing on the Sat 5 in particular. Check it out. This is a very informative site, makes me sound much smarter than I really am!<br /><br />http://yarchive.net/space/rocket/exhaust_backflow.html<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
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CalliArcale

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I think you could even see a little of this effect in the STS-121 ET camera images yesterday. I'm not totally sure; part of the trouble is that unlike the Saturn V's kerosene-powered first stage, the Shuttle is powered by cryogenics, which means the plume is almost invisible. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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qso1

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IIRC, there is a name for it, plume recirculation which is due to what has already mentioned by the more knowledgeable posters here who have already posted. I can't recall where I heard that term. <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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