We once had a similar request. We tried various ideas before the real event. The one that worked was to attach the urn to a long pole (about 6 feet) with plenty of gaffer tape. The lid was secured also by a gaffer tape hinge and a piece of gaffer tape holding it closed with some cord to pull this tape off. At about 60 Kts we slowly put the urn out into the airflow, lid first and when fully extended we inverted the urn and pulled the tape off the lid. Ashes scattered well, Job done! Hope this helps