how to make roses using whipping cream
I don't think you can, even with stabilized whipped cream. It's just too soft.
Try adding some pudding mix to the whipped cream to stiffen it a little. Makes it easier to pipe it. Not sure if it will work, but worth a shot! Let us know if it works!
Yaknow, I've made roses out of butter, so I'd bet that if the whipped cream was whipped just shy of turning into butter it would be stiff enough. Might not last too long though.
Another thought: I've put buttercream roses on whipped cream cakes, if the stiffened cream doesn't work out...