They definately had contact and delayed action fuses for the bombs. Getting a bomb to detonate above ground was a bit iffy, I've seen pictures of bombs with contact fuses extending a yard or so out the front of the bomb. (Daisy cutters???)
There is a WWII war time documentry film called "Mission for today", in it they talk about bombing factories, they explain through use of drawings that with contact fuses the bombs detonate on the roof of the factories causing minimal damage to plant and machinery. By using delayed action fuses the bombs detonate at the ground level for maximum damage.
Cheers!
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