I have read a lot about D-bows but actually have no clue what a D-bow is? Just a type of longbow??
D bows refer to the shape of the bow when it is strung.
http://www.tradgang.com/docs/trad.html
that is a link Ole Rob put together. Rob tends to be the D guru and could more than likely provide you more information than you could read on this topic.
If we really want to get technical here....a "D" bow historically referred to the cross section of the bow's limb. English longbows would be considered a "D" bow. In more recent times, a "D" bow means the shape when braced - like a straight limbed Howard Hill style American longbow.
What he said!^ Dont ever listen to a glass guy
Yes, what John said and fairly easy to build as a self bow too