Piotr writes:

 

"... no English syllable can begin with /pw/, /bw/, or /fw/".

 

I'm not really disagreeing with Piotr, but there will always be exceptions. 'Bwana' is a borrowing via Swahili meaning 'boss', 'master'.

 

Small children who realize orthographic L and R as a W easily make the combination of /bw/: "He's my widdle bwuvver".

 

I notice that /bw/, /fw/, and /vw/ are actually rather easy clusters. My English speaking linguistic sensibilities, however, finds the sounds /bw/-/pw/ too indistinct for easy discrimination, tho' I think a little practice would clear that up.

 

A wicked thought. Were someone in need of forming a number of new English words, or even better, some new lexical prefixes, the /bw/  and /fw/  combinations offer themselves as a means of fully phonemicizing these word-initial sounds. The natural following vowel would be schwa, though just about the whole English repertory could accomodate it.

 

Mark.