The Older Gentleman schreef:

Are there any diesel aer-engines, or diesel car engines frequently used
in aircraft? I had the impression that diesel aero-engines died with
airships and the Junkers 86, but I'm always willing to learn....

Not sure if you are aware but you are posting to
news://rec.aviation.homebuilt ; where this subject has been discussed
several times. Though of course the story is not ended, not by a long
way. I am considering an aero-conversion of the Subaru flat-4 diesel but
will need engineering help as I'm not schooled in mechanics.

If you are really curious about diesels in airships, consult
www.dair.co.uk - that engine scales down the idea behind the JuMo diesels.

KA