Yes, I also know about this spelling (auto, motor und sport, 5/1964). On the other hand, the son of the builder, Thomas P. Otten, writes the name in two words.
It would be logical for 'Jetkomet' to be written in one word after 'Jetstar' is also written in one word.
Thomas P. Otten writes 'Jetstar' in one word, 'Jet Komet' separately