Airshipwreck, Len Deighton and Arnold Schwartzman Jonathan Cape Limited, 30 Bedford Square, London, WC1 ISBN 0-224-01384-X, First Published 1978
United States Naval Air Station Lakehurst, NJ "The Hindenburg Memorial"
Distinction is made ... rigid versus non-rigid in both above.
Regarding "manoeuverable" ... FAA rules on "right-of-way" ... ballons highest as it is ain't got none! At the mercy of the winds ... of course ballast helps.