4806 kg.cm2 for a 62" wide chord HP Warp Drive (including bolts and
faceplate, but not spinner, all of which would be negligible at such a small
radius of gyration).
The benefit of the small diameter props that Europas run should favour being
well within the Rotax gearbox inertial load limits (which I don't think were
changed for the 912S or 914, even though the higher gearing ratios of these
would suggest that they might).
So it should be other users of 912s that are suffering more than us.
Duncan Mcf.
PS Will Bob Harrison please stop sniggering at all this!
----- Original Message -----
From: "M.J. Gregory" <m.j.gregory@talk21.com>
Subject: RE: Europa-List: Rotax starting - 912S
>
> Could these problems be exacerbated by exceeding the maximum propeller
> mass-inertia limit recommended by Rotax? In the case of the 912 this was
> 6000 kg-cm squared.
> Does anyone know what the current recommended limits are for the 912S and
> the 914, and how commonly-used propellers such as Warp Drive compare to
> them?
>
> Mike
> Europa Club Safety Officer
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com]On Behalf Of Ami McFadyean
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Rotax starting - 912S
>
> <ami@mcfadyean.freeserve.co.uk>
>
> That being so, the 'shaking and banging' is likely caused by the low
> frequency primary resonance (torsional and/or blade-flap) that is
inevitably
> present below normal cranking speeds. In the absence of any damping, the
> forces produced by resonance will build-up towards infinity. The crank and
> gearbox get hit with similar forces too; its just that the sprag is the
weak
> link in the chain (and, if it's any consolation, cheaper than a new
crank!).
> However, damping of resonance is provided by the friction clutch in the
> gearbox; hence Rotax's insistence that this be maintained at the upper
> limit. Also anything that accelerates the cranking engine quickly through
> and clear of the resonant band should help (i.e. powerful battery, good
> contacts, high torque motor). We have to hope that it is the 'shaking and
> banging' ONLY that causes the problem, not the loads of normal starting.
>
> Last Summer, there was a certain 912S CT that was regularly shaking the
> carburettors out of the mounting sockets on start up, possibly exacerbated
> by the big floppy 2-blade prop it had.
>
> Duncan McF.
> ----- Original Message -----
> From: "P.A.D.Clarke" <paddyclarke@lineone.net>
> To: <europa-list@matronics.com>
> Subject: Re: Europa-List: Rotax starting - 912S
>
>
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