Mailing List flyrotary@lancaironline.net Message #21429
From: Todd Bartrim <haywire@telus.net>
Subject: re; CVT (continuously variable transmission)
Date: Thu, 5 May 2005 00:53:29 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Has anyone heard of any research toward using these for PSRU's?  I have no
idea how heavy they are, or if they could be dumbed down from the factory
computers, or if they could be made to survive.  Sure would be a nice option
if they could work.  
 
Rusty
 
 As mentioned in the article, these are used in very succesfully in
snowmobiles (the pulley type). In the old days they would eat belts, but
they've come along ways since then. The sled I currently ride pushes 130hp and
has never blown a belt in 5 seasons of riding. I did change it after the first
2 seasons, but still carry it as a spare. Mountain riding is very demanding on
the clutches, much more than I'd expect in an aircraft application so I think
reliabilty should be good. My peak power is at 8400 rpm so the primary engages
at 4000rpm and begins the upshift untill 8400 is reached at which time the
secondary limits this and controlls the backshift as load demands. When not
heavily loaded (like cruising down a trail) it will not downshift, allowing
lower rpm cruise for fuel efficiency, but will instantly respond to an
increased load (climbing a hill).
  However I always wondered why they're not used with Rotax engines in ultra
lights? Since the Rotax is the power for Ski-Doo, I'd have expected that
someone would have used the combination in an UL aircraft. But since it didn't
apply to my needs I didn't think about it for long.
   I'd never heard of the torroidial CVT before, but the article was very
interesting and I can certainly invision one of these as a PSRU. It's an
interesting concept that I'd like to see pursued, but right now my old brain
is running out of RAM so I've got to reserve that for school right now.
  Why don't you try a pulley type CVT on one of your multitude of planes? How
many do you have now? And does your wife know? How many actually fly? :-)

Todd Bartrim    (big ole' EC2, EM2 & planetary geared RD2)

C-FSTB RV-9endurance
13B Turbo

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