X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4178686 for flyrotary@lancaironline.net; Thu, 25 Mar 2010 15:03:57 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.0 c=1 a=mi2RgyCns7oA:10 a=f4jGXqvpAAAA:8 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=QdXCYpuVAAAA:8 a=7g1VtSJxAAAA:8 a=ekHE3smAAAAA:20 a=UretUmmEAAAA:8 a=Ia-xEzejAAAA:8 a=kviXuzpPAAAA:8 a=FE_Wm1HGU4tCtcmAeg4A:9 a=6zQCn2UJ-9JLmLAO0tkA:7 a=BWds9gAD9WQCEQIDSnyBAjbDApkA:4 a=wPNLvfGTeEIA:10 a=1vhyWl4Y8LcA:10 a=EzXvWhQp4_cA:10 a=4vB-4DCPJfMA:10 a=Tv_OCGGkAlYZgz9S:21 a=cKdYdTVhMNJ66IIZ:21 a=SSmOFEACAAAA:8 a=K2UG9ca78m0dfqddN3kA:7 a=t6RVXXEeukLJUx0aNmf-gLYsXr0A:4 a=OwWtFriwURBAJcif:21 a=rPcZ__JFyDACNHLt:21 X-Cloudmark-Score: 0 X-Originating-IP: 75.191.186.236 Received: from [75.191.186.236] ([75.191.186.236:3926] helo=computername) by cdptpa-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 7D/EB-06757-A73BBAB4; Thu, 25 Mar 2010 19:03:23 +0000 From: "Ed Anderson" Message-ID: <7D.EB.06757.A73BBAB4@cdptpa-omtalb.mail.rr.com> To: "'Rotary motors in aircraft'" Subject: Rotating Disc Vibration nodes was [FlyRotary] Re: Adaptor plate rivets Date: Thu, 25 Mar 2010 15:03:29 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01CACC2C.548AF2A0" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcrMSIjmuphkPufbT3+AJJ9yL9O9pAAAmElw In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0003_01CACC2C.548AF2A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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. =20 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 =96 = 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. =20 Here is an URL that provides a drawing of how such nodes might form on a disc =20 http://demonstrations.wolfram.com/NormalOscillatoryModesOfRotatingOrthotr= opi cDisks/ =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm =20 _____ =20 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 =20 Al, =20 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. =20 =20 Mark S. =20 On Thu, Mar 25, 2010 at 11:22 AM, Al Gietzen 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. =20 Normally washers are needed only under the side that you=92re turning to = apply the force; unless needed to provide shimming or a more uniform or larger surface. The -6A length has a 3/8=94 grip length, and I assumed the = plate was 1/8=94 and the flange =BC=94. If the thickness is less I may have to = get some more, or thicker, washers. =20 Al =20 ------=_NextPart_000_0003_01CACC2C.548AF2A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Have not gone out and checked my = rivets on my R1C, will do that this weekend.=A0 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.=A0 There is the possibility that if the disc = were in some oscillatory mode that the smoking rivets might be caused by with = the rivets =A0being 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 =A0rivet.

 

In the end, it may be important to = know what is causing this.=A0 The 20Bs should be smoother than the 13Bs, on = the other hand, they do have a different firing frequency.=A0 For the same RPM the = number of firing pulses from the 20B are 1/3 higher than the 13B over the same time = period.=A0 =A0That could possibly induce vibration nodes in the disc that the 13B (which = has longer duration between firings pulses).=A0 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 =A0between firings pulses – where = =A0not so for the more frequent pulses of the 20B. =A0=A0The higher the frequency of = the input, the stiffer structure that can be caused to vibrate. =A0A vast over simplification, but thought I would throw it out just incase somebody = had a finite analysis package sitting on their computer.=A0 =A0=A0Just a = WAG.

 

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

 

http://demonstrations.wolfram.com/NormalOscillatoryMo= desOfRotatingOrthotropicDisks/

 

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.  

 

Mark S.

 

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 =BC”.  If the thickness is less I may have to get some more, or thicker, = washers.

 

Al

 

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