Tans in Circles

The following pictures show n tans with leg 1 packed inside the smallest known circle (of radius r).

1.
           2.
           3.
r = 1/√2 = .707+
Trivial. 		r = 1/√2 = .707+
Trivial. 		r = (6 + √2)/8 = .926+
Found by Serhiy Grabarchuk
in April 2005.

4.
           5.
           6.
r = 1
Trivial. 		r = 1.125+
Found by Maurizio Morandi
in July 2007. 		r = 1.198+
Found by Maurizio Morandi
in July 2007.

7.
           8.
           9.
r = 1.265+
Found by Maurizio Morandi
in August 2007. 		r = √(1+1/√2) = 1.306+
Found by Serhiy Grabarchuk
in April 2005. 		r = 1.377+
Found by David W. Cantrell
in August 2007.

10.
           11.
           12.
r = 1.428+
Found by Maurizio Morandi
in July 2007. 		r = 1.480+
Found by David W. Cantrell
in August 2007. 		r = 1.509+
Found by David W. Cantrell
in August 2007.

13.
           14.
           15.
r = 1.559+
Found by Serhiy Grabarchuk
in April 2005. 		r = √10/2 = 1.581+
Found by Serhiy Grabarchuk
in April 2005. 		r = 1.667+
Found by Maurizio Morandi
in July 2007.

16.
           17.
           18.
r = 1.746+
Found by David W. Cantrell
in August 2007. 		r = 1.806+
Found by David W. Cantrell
in August 2007. 		r = 1.834+
Found by David W. Cantrell
in August 2007.