Harold's Purple Crayon
From Jenny Everywhere Wiki
In one universe, Harold's Purple Crayon (PROSE: Falling Short) was the improbable name of the airship piloted by Professor Wulfe, Jenny Everywhere's friend and mentor. (PROSE: Old Foundations)
The Harold's Purple Crayon had a cloaking device which could be switched on and off on command. During a nightly operation where the disguised airship flew Jenny Everywhere close enough to an enemy base that she could hang-glide down over the property to try and take some pictures, Jenny radioed Wulfe asking him to create a distraction for the guards. (PROSE: Falling Short) With his typical lack of restraint, (PROSE: Old Foundations) the Professor uncloaked the whole airship, which soon came under fire. (PROSE: Falling Short)