From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Flexplate cracks
Date: Fri, 10 Jan 2025 11:31:39 +0800
References: <list-3781972@lancaironline.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-3781972@lancaironline.net>
Message-Id: <DD17154A-418D-4545-B2F2-B6CAE34FE4C1@gmail.com>

Hi M

I was wondering the same thing.=20

What I discovered first of all was that flex plates are designed to flex =
(funny that) and cracking is not limited to our setup.=20
There are companies that specialise in stronger flex plates, =
particularly for modified and higher horsepower engines.

Since our engines are being used at a higher horsepower per unit time =
and therefore higher stress (assumption) perhaps our setup could be =
likened to race applications.
But then our hours of use would be significantly lower (assumption) than =
an average vehicle, but perhaps not a race application.
Is the cracking we are seeing consistent with race applications? But =
they dont race automatics, do they?

So my take on this is that perhaps the flexing of the plate in our setup =
is to some extent higher than OEM.

Our options seem to be:
1. Replacing the OEM flex plate with a stronger part. Steve B being the =
latest going down that track and in his case also removing the rubber =
isolation in the process.
2. Connect direct to the eccentric shaft and therefore taking the stress =
off the Flex Plate doing away with the damping mechanism which Tracy =
did, and perhaps is still doing. Would be real nice to know.

Like M, I would appreciate hearing what others know or are thinking or =
doing.

Steve Izett


> On 10 Jan 2025, at 2:15=E2=80=AFam, Marc Wiese cardmarc@charter.net =
<flyrotary@lancaironline.net> wrote:
>=20
> Has the cause of these cracks been uncovered, and if so, what is the =
current thinking on it? An AL racing plate?
> M
> Sent from my iPhone
>=20
>> On Jan 9, 2025, at 1:31=E2=80=AFAM, Steven W. Boese SBoese@uwyo.edu =
<flyrotary@lancaironline.net> wrote:
>>=20
>> =EF=BB=BFSteve,
>>=20
>> I didn=E2=80=99t see the cracks prior to disassembly and doubt that =
they could have been seen on the counterweight side very well -if at =
all- when assembled.
>>=20
>> I replaced the Flexplate with a steel flywheel about a year ago.  =
Since then, I replaced the four rubber dampers with machined aluminum =
discs giving a solid connection and then dynamically balanced the =
system.  This was done because maintaining a dynamic balance wasn=E2=80=99=
t possible with the dampers.  Only a few hours of flight have occurred =
in this configuration so far and there has been no indication of =
problems resulting from this change.
>>=20
>> Steve Boese
>>=20
>>> On Jan 8, 2025, at 11:03=E2=80=AFPM, Stephen Izett =
stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
>>>=20
>>> =EF=BB=BF=E2=97=86 This message was sent from a non-UWYO address. =
Please exercise caution when clicking links or opening attachments from =
external sources.
>>>=20
>>>=20
>>> Hi Steve
>>>=20
>>> Is this recent then?
>>>=20
>>> I=E2=80=99m not able to get to my aircraft at present to check my =
flex plate which has probably seen 50 hours of service.
>>>=20
>>> Was it possible to see these cracks assembled?
>>>=20
>>> I would appreciate your reflections on Tracys latter choice to =
remove the damper, and particularly when using a timber/glass prop such =
as an MT.
>>>=20
>>> It would be great to have an update and current info from Tracy =
regarding his no damper hours if anyone can contact him.
>>>=20
>>> Very helpful, thanks again Steve
>>>=20
>>> Steve
>>=20
>> --
>> Homepage:  http://www.flyrotary.com/
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>=20
>=20
>=20
> --
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