Giving estimates on R&D software projects

Recently I was at a seminar were one of the participants asked a question regarding estimating properly when working on an R&D project from the expert panel.

The question was “How do we give proper deadlines when we are working on R&D projects, because when we start going into research we come up with so many stumbling blocks that we need to figure out so many things and our estimations goes out of the window”.
http://estimating-the-unknown.blogspot.com/