Have not gone out
and checked my rivets on my R1C, will do that this weekend. However,
there is one possibility for the cause of the smoking rivets that I have not
heard addressed and that is vibration nodes of a rotating disc. There
is the possibility that if the disc were in some oscillatory mode that the
smoking rivets might be caused by with the rivets being at the nodes
of certain modes (like that?) of vibration which could be causing the holes
in the discs to be sliding up and down the shaft of
rivet.
In the end, it may
be important to know what is causing this. The 20Bs should be smoother
than the 13Bs, on the other hand, they do have a different firing
frequency. For the same RPM the number of firing pulses from the 20B
are 1/3 higher than the 13B over the same time period. That
could possibly induce vibration nodes in the disc that the 13B (which has
longer duration between firings pulses). The long time between firings
in the 13B might permit the mass/structure of the assembly to dampen the
amplitude of any such induced vibration between firings pulses – where
not so for the more frequent pulses of the 20B. The higher
the frequency of the input, the stiffer structure that can be caused to
vibrate. A vast over simplification, but thought I would throw it out
just incase somebody had a finite analysis package sitting on their
computer. Just a WAG.
Here is an URL that
provides a drawing of how such nodes might form on a
disc
http://demonstrations.wolfram.com/NormalOscillatoryModesOfRotatingOrthotropicDisks/
From:
Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Thursday, March 25, 2010 2:25
PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Adaptor plate
rivets
Al,
I had a bunch of AN-6A bolts, so I used them with
two thick washers, one under the head and one under the nut. I mainly
wanted to ensure that the shank went all the way through both pieces.
You might be able to use AN-5.5A or even AN-5A bolts if you use only
one thin washer under the nut.
On Thu, Mar 25, 2010 at 11:22 AM, Al Gietzen <ALVentures@cox.net>
wrote:
To answer your
question about the washers, I used thick washers on both sides. But
I'll have to remove them all in order to replace the AN-6A bolts with
AN173-6A's. I'm hoping the bolts arrive by this weekend so I can start
putting everything back together.
Normally washers
are needed only under the side that you’re turning to apply the force;
unless needed to provide shimming or a more uniform or larger surface.
The -6A length has a 3/8” grip length, and I assumed the plate was 1/8” and
the flange ¼”. If the thickness is less I may have to get some more,
or thicker, washers.
Al