X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qmta01.emeryville.ca.mail.comcast.net ([76.96.30.16] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4179151 for flyrotary@lancaironline.net; Thu, 25 Mar 2010 21:57:19 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.30.16; envelope-from=hoursaway1@comcast.net Received: from omta23.emeryville.ca.mail.comcast.net ([76.96.30.90]) by qmta01.emeryville.ca.mail.comcast.net with comcast id xc8z1d0061wfjNsA1dwksu; Fri, 26 Mar 2010 01:56:44 +0000 Received: from sz0081.ev.mail.comcast.net ([76.96.26.137]) by omta23.emeryville.ca.mail.comcast.net with comcast id xdwj1d00X2xV6SL8jdwjRZ; Fri, 26 Mar 2010 01:56:44 +0000 Date: Fri, 26 Mar 2010 01:56:43 +0000 (UTC) From: hoursaway1@comcast.net To: Rotary motors in aircraft Message-ID: <573890620.3478891269568603824.JavaMail.root@sz0081a.emeryville.ca.mail.comcast.net> In-Reply-To: Subject: Re: [FlyRotary] Rotating Disc Vibration nodes was [FlyRotary] Re: Adaptor plate rivets MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_184165_189393982.1269568603823" X-Originating-IP: [76.20.183.210] X-Mailer: Zimbra 5.0.19_GA_3172.RHEL5_64 (ZimbraWebClient - IE6 (Win)/5.0.19_GA_3177.RHEL5_64) ------=_Part_184165_189393982.1269568603823 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable How about large alum. rivits with very large shaft diam. for more shaft con= tact with both plts., would have to be large=C2=A0=C2=A0 machine/press=C2= =A0=C2=A0 set in place.=C2=A0 Just a thought.=C2=A0 David R. Cook=C2=A0 =C2= =A0RV6A Rotary.=C2=A0 (snowless in MI finaly)=20 ----- Original Message -----=20 From: "Ed Anderson" =20 To: "Rotary motors in aircraft" =20 Sent: Thursday, March 25, 2010 3:03:29 PM GMT -05:00 US/Canada Eastern=20 Subject: [FlyRotary] Rotating Disc Vibration nodes was =C2=A0[FlyRotary] Re= : Adaptor plate rivets=20 Have not gone out and checked my rivets on my R1C, will do that this weeken= d.=C2=A0 However, there is one possibility for the cause of the smoking riv= ets that I have not heard addressed and that is vibration nodes of a rotati= ng disc.=C2=A0 There is the possibility that if the disc were in some oscil= latory mode that the smoking rivets might be caused by with the rivets =C2= =A0being at the nodes of certain modes (like that?) of vibration which coul= d be causing the holes in the discs to be sliding up and down the shaft of = =C2=A0rivet.=20 In the end, it may be important to know what is causing this.=C2=A0 The 20B= s should be smoother than the 13Bs, on the other hand, they do have a diffe= rent firing frequency.=C2=A0 For the same RPM the number of firing pulses f= rom the 20B are 1/3 higher than the 13B over the same time period.=C2=A0 = =C2=A0That could possibly induce vibration nodes in the disc that the 13B (= which has longer duration between firings pulses).=C2=A0 The long time betw= een firings in the 13B might permit the mass/structure of the assembly to d= ampen the amplitude of any such induced vibration =C2=A0between firings pul= ses =E2=80=93 where =C2=A0not so for the more frequent pulses of the 20B. = =C2=A0=C2=A0The higher the frequency of the input, the stiffer structure th= at can be caused to vibrate. =C2=A0A vast over simplification, but thought = I would throw it out just incase somebody had a finite analysis package sit= ting on their computer.=C2=A0 =C2=A0=C2=A0Just a WAG.=20 Here is an URL that provides a drawing of how such nodes might form on a di= sc=20 http://demonstrations.wolfram.com/NormalOscillatoryModesOfRotatingOrthotrop= icDisks/=20 Ed Anderson=20 Rv-6A N494BW Rotary Powered=20 Matthews, NC=20 eanderson@carolina.rr.com=20 http://www.andersonee.com=20 http://www.dmack.net/mazda/index.html=20 http://www.flyrotary.com/=20 http://members.cox.net/rogersda/rotary/configs.htm#N494BW=20 http://www.rotaryaviation.com/Rotorhead%20Truth.htm=20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Mark Steitle=20 Sent: Thursday, March 25, 2010 2:25 PM=20 To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Adaptor plate rivets=20 Al,=20 I had a bunch of AN-6A bolts, so I used them with two thick washers, one un= der the head and one under the nut. =C2=A0I mainly wanted to ensure that th= e shank went all the way through both pieces. =C2=A0You might be able to us= e AN-5.5A or even AN-5A bolts if you use only one thin washer under the nut= . =C2=A0=20 Mark S.=20 On Thu, Mar 25, 2010 at 11:22 AM, Al Gietzen < ALVentures@cox.net > wrote:= =20 To answer your question about the washers, I used thick washers on both sid= es. =C2=A0But I'll have to remove them all in order to replace the AN-6A bo= lts with AN173-6A's. =C2=A0I'm hoping the bolts arrive by this weekend so I= can start putting everything back together. =C2=A0=20 Normally washers are needed only under the side that you=E2=80=99re turning= to apply the force; unless needed to provide shimming or a more uniform or= larger surface.=C2=A0 The -6A length has a 3/8=E2=80=9D grip length, and I= assumed the plate was 1/8=E2=80=9D and the flange =C2=BC=E2=80=9D.=C2=A0 I= f the thickness is less I may have to get some more, or thicker, washers.= =20 Al=20 ------=_Part_184165_189393982.1269568603823 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable <= div style=3D'font-family: Arial; font-size: 12pt; color: #000000'>How about= large alum. rivits with very large shaft diam. for more shaft contact with= both plts., would have to be large   machine/press   s= et in place.  Just a thought.  David R. Cook   RV6A Rot= ary.  (snowless in MI finaly)
----- Original Message -----
From:= "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in a= ircraft" <flyrotary@lancaironline.net>
Sent: Thursday, March 25, 2= 010 3:03:29 PM GMT -05:00 US/Canada Eastern
Subject: [FlyRotary] Rotatin= g Disc Vibration nodes was  [FlyRotary] Re: Adaptor plate rivets

Have not gone out and= checked my rivets on my R1C, will do that this weekend.  However, the= re is one possibility for the cause of the smoking rivets that I have not h= eard 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.

 <= /P>

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 h= igher than the 13B over the same time period.   That could possib= ly induce vibration nodes in the disc that the 13B (which has longer durati= on 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 =E2=80=93 where &nb= sp;not so for the more frequent pulses of the 20B.   The higher t= he frequency of the input, the stiffer structure that can be caused to vibr= ate.  A vast over simplification, but thought I would throw it out jus= t incase somebody had a finite analysis package sitting on their computer.&= nbsp;   Just a WAG.

 <= /P>

Here is an URL that p= rovides a drawing of how such nodes might form on a disc

 <= /P>

http://demonstrations.wolfram.com/NormalOscillatoryModesOfR= otatingOrthotropicDisks/

 <= /P>

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
<= SPAN style=3D"FONT-WEIGHT: bold">Sent: Thursday, March 25, 2010 = 2:25 PM
To: Rotary motor= s in aircraft
Subject: [= FlyRotary] Re: Adaptor plate rivets

 

Al,

 

I had a bunch of AN-6A bolts, so I used them with two thi= ck 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 m= ight be able to use AN-5.5A or even AN-5A bolts if you use only one thin wa= sher under the nut.  

 

Mark S.

 

On Thu, Mar 25, 2010 at 11:22 AM, Al Gietzen <ALVentures@cox.net> w= rote:

To answer your question about the washers, I use= d thick washers on both sides.  But I'll have to remove them all in or= der 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. &nb= sp;

Normally washers are needed on= ly under the side that you=E2=80=99re turning to apply the force; unless ne= eded to provide shimming or a more uniform or larger surface.  The -6A= length has a 3/8=E2=80=9D grip length, and I assumed the plate was 1/8=E2= =80=9D and the flange =C2=BC=E2=80=9D.  If the thickness is less I may= have to get some more, or thicker, washers.

 

Al

=

 

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