Happy New Year to you all from Mistral!

   As Mistral is reviewing some parts of its design for the soon-to-come
   3-rotor models,  I'd like to submit the following topics for an informal
   group brainstorming:

   1). What do you think of dry vs wet oil sump? All comments and
   suggestions
   welcome

   2). As it is impractical, if not impossible, to make a fully aerobatic
   rotary engine on the basis of a Mazda block, what level of "limited"
   aerobatics capabilities is acceptable/wished for?  I am especially
   concerned
   with vertical or near vertical manoeuvres... tricky situations for
   rotaries...

   Thanks in advance for the feedback.

   Francois Badoux


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Francois,

Happy new year to everyone at Mistral.  Glad to see you are considering
such issues.  FWIW, I do positive G aerobatics all the time loops,
aileron rolls barrel rolls, wing overs. split S and the like.  I have
also done snap rolls and spins but don't do them on a regular basis.
There was not noticeable effect on my 13B or turbo from the gyroscopic
loads.  I have a wet sump so keep it positive G.  I do more aerobatics
than most RV pilots so I would say the bulk of your potential business
would be happy with a wet sump.

Obviously competition aerobatics require sustained negative g's and a
dry sump.  Oil pooling in the rotors is obviously not a problem and off
the top of my head I can't think of any reason that a dry sump would not
cover standard competition inverted flight (outside loops and inverted
passed over the show area).

Your point about vertical flight (hanging on the prop) is a concern.
The front cover will fill with oil and the front counter weight will be
spinning in a pool of oil.  Also, the front oil seal is not intended to
be immersed in oil and would probably leak.  Neither of these problems
are insurmountable.  I know you use your own front cover and could
probably easily fix the oil seal problem.  It would also be possible to
build an aftermarket front counterweight that was a continuous ring only
heavier on the necessary side.  This is obviously a more difficult
task.  A machined aluminum or composite adaption to the stock counter
weight would probably be an easier solution.

Good luck,