One Machi Going Up, Upside Down

Wait a minute... if,

$r=a+bcos(\theta)$   and     $a<0$,  $|a|>b>0$

then the curve should be upside down,

The tube should lift this way up where the upside $\frac{v^2}{r}$ has a higher value as $r$ is smaller, $v$ being constant throughout the tube.