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2019-11-21 14:03 nesdori  
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this demo cave demonstrates two variants of 5 bflies moving straight up. before you read on, i recommend opening  Arno 's article about bnb-formation:  
  
<a href="https://www.boulder-dash.nl/forum/viewtopic.php?t=636&start=13&postdays=0&postorder=asc&highlight=" target="external">https://www.boulder-dash.nl/forum/viewtopic.php?t=636&start=13&postdays=0&postorder=asc&highlight=</a>  
  
i'll use definitions and phase numbering introduced in that article.  
  
although these formations look like independent formations because the formations are quite dense (especially leftmost variation 1), they in fact consist of two bnb:s and a hitchhiker which gyrates between them. but there's a twist: the hitchhiker occasionally integrates into bnb-formation and one fly which previously was part of bnb-formation becomes a hitchhiker!  
  
the initial fly positions of both variations on this cave are same but initial directions of flies differ and the formations look different when they are flying. i'll use this fly numbering:  
  
12.3  
..4.  
..5.  
  
flies 1 and 2 form a regular bnb-formation which always stays intact and it's role is just to help the hitchhiker fly to stay along.  
in variation 1 (the left formation) the initial fly directions are 1=up and 2=left so it's phase # 3 in  Arno 's article. Variation 2 (on the right) is 1=up, 2=down (phase 2 in the article). This phase shift is the only difference between variation 1 and 2. the remaining group of three flies is the same.  
  
in the initial position flies # 3 and 5 form a bnb-formation (phase 2: 3=L and 5=R). but instantly after this phase there's a switch: on phase 3, 3=D and 4=U and 5 becomes the external hitchhiker.  
so fly 3 is a permanent "driver" of the transforming bnb group and 4 and 5 variate being "the front seat passenger" and "a hitchhiker". the transition occurs from phase 2 to phase 3 and the roles are kept one full bnb cycle of 5 frames and then again switched.  
  
technically speaking this is not a genuine new formation. it's a formation consisting of two bnbs and hitchhiker but it's very exceptional one. it's the first formation where a hitchhiker uses two existing formations to hang on and the first formation where a hitchiker momentarily integrates into a formation.  
  
because of the triangle drama i named the hitchhiker "babette" so the long name for this formation is "bob & bobette and bob & bobette & babette". the latter bob clearly can't decide with whom he would like to dance with and changes the partner constantly :)

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2019-11-21 17:06 shredder  
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very nice! im struggling with cave with similar formation launch, but i have problems with catching 5 bflies to the shredding machine ;)

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2019-11-21 19:51 Arno  
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great  nesdori ! thanks for the demo cave and explanation! this seems to be a very special (new) type of dff! :-)

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2019-11-21 20:48 dustin  
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wow, that looks great!

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2019-11-22 20:08 Arno  
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the left b&b runs independently, but the B&b&b is held together by the b&b.  
  
so in terms of "free riders", instead of a a single free riding fly, we have here a formation of 3 bflies, free riding with the b&b...  
this is a very special formation indeed...! :-)

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2019-11-23 15:55 nesdori  
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yes, that's another way of thinking that entire B&b&b is free riding, in a way it is :)