You can look up with Ctrl-Numpad 8
. But as soon as you release the keys, you return to the original view.
Maybe it's just my keyboard, but I have found if you release the number key before the ctrl key, the view will lock to that orientation. Press another view key to unlock it again. And of course, if you release the ctrl key before the number key, the view will revert back to forward view as soon as you let go of the key.
Edit: Thanks Jack, I do indeed have it backwards. Release the ctrl key first, and the view will lock.