If you've got some way on when you start the prop spinning, this is pretty common with many of the folding props. On thing worth trying is to spin, at say 1200 rpm, for a moment, in reverse, to help the prop open, then back to low RPM, pop through neutural, and into forward, and then bringing up the revs, fairly quickly. This will often get the prop open when it might otherwise be inclined to stay shut.
- David
