Hello Marc,
thanks for the indication about the cross section. I made a few heavy longbows of european ash and used the same setup: about 3.5cm wide and about 2.5cm thick at the grip , tapering to 13mm tips. The belly beeing sligthly rounded, not as high crowned as with yew and heat treated. they shot good.
I wonder if the other way round more would be possible: a perfectly flat belly and a trapped or rounded back. I just made a black locust bow like that and without heat treating. It took almost no follow and came out phisically very light and very well shooting. Black locust beeing very tension strong and rather compression weak benefitted extremely from this design and I must say that I like it also esthetically, I'm not affected by the english-design-is-best-of-the-world syndrome
Regards,
gian-luca