X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wproxy.gmail.com ([64.233.184.198] verified) by logan.com (CommuniGate Pro SMTP 5.0.6) with ESMTP id 918557 for flyrotary@lancaironline.net; Mon, 09 Jan 2006 10:06:21 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.233.184.198; envelope-from=russell.duffy@gmail.com Received: by wproxy.gmail.com with SMTP id 37so3344292wra for ; Mon, 09 Jan 2006 07:05:36 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:from:to:subject:date:message-id:mime-version:content-type:x-priority:x-msmail-priority:x-mailer:importance:in-reply-to:x-mimeole; b=mKMc48GqBnlTZRcHXV5gEJqzQvMuPlYQmK7VOcIjvXsKQxEaEx+iVR8kFfpMhQwMW0bgStNAONx/MdNDqe7gG2mYtnbis9na91VOtXzlQR4OaaUJwOdF7OIM+oP6yw0xHRg+kBrKVrPAKglzYc3sFdmoEaMDCx3cSncJ78o88Pg= Received: by 10.54.139.2 with SMTP id m2mr7676394wrd; Mon, 09 Jan 2006 07:05:35 -0800 (PST) Return-Path: Received: from rd ( [65.6.194.9]) by mx.gmail.com with ESMTP id 35sm2678273wra.2006.01.09.07.05.34; Mon, 09 Jan 2006 07:05:35 -0800 (PST) From: "Russell Duffy" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: More single rotor running Date: Mon, 9 Jan 2006 09:05:36 -0600 Message-ID: <000101c6152e$25f6ad80$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0002_01C614FB.DB5C3D80" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 This is a multi-part message in MIME format. ------=_NextPart_000_0002_01C614FB.DB5C3D80 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable However, I agree with Lynn on the fly wheel being the issue with the = torque pulses. My load on the test stand is direct coupled, via a donut = dampener to the load prop. I have the space in the fly wheel housing to add weight = if necessary.=20 =20 Hi Richard, =20 Thanks for the comments. I took a look yesterday, and will be hard = pressed to add much weight to the dampener bolt locations. I can probably add = 1-2 large washers at each spot, though from what Lynn said, this may be more than enough to make a difference. =20 =20 =20 At the RPM you are talking about, I do not think there is an engine = balance problem. Even with a badly balanced engine, related vibrations did not = show up below 4000RPM on my engine.=20 =20 I've had the engine up to about 5000, but couldn't richen the mixture = enough to do much. Still, aside from the odd beat frequency prop oscillation, = I didn't notice any vibration. Once the engine breaks out of the = 2500-3100 rpm vibration pit, it's quite smooth. =20 =20 As for the prop oscillation thing, I've come to believe that the prop = pitch is way too high for the single rotor. I'm using a Warp Drive, 68" = diameter, 3 blade prop, which is exactly the same as what I used on the RV-3 initially. When I set the initial pitch, I just picked a round number, = and set the tip angle at 15 degrees, since that number was stuck in my brain = for some reason. =20 =20 Now that I looked it up, I found that 15 degrees was the highest pitch I ever tried on the RV-3, and that was with the turbo, and 5 psi of boost. The 13B had a 2.17 drive, rather than the 2.85, but still, me thinks I = need to back off to about 10 degrees for now. I even found notes about prop stalling issues when running that pitch on the RV-3, so with all the obstacles around the prop on the Kolb, I've almost certainly got some = sort of asymmetric stalling issues going on. I'm just sure this is causing = the odd beat frequency vibration, and prop oscillation. This will be an = easy thing to try, so I'll find out pretty soon if this is it.=20 =20 Thanks, Rusty (Gmail still working)=20 =20 ------=_NextPart_000_0002_01C614FB.DB5C3D80 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
However, I = agree with Lynn=20 on the fly wheel being the issue with the torque pulses. My load on the = test=20 stand is direct coupled, via a donut dampener to the load prop. I have = the space=20 in the fly wheel housing to add weight if necessary. 
 
Hi Richard,
 
Thanks for the comments.  I took a look = yesterday,=20 and will be hard pressed to add much weight to the dampener bolt=20 locations.  I can probably add 1-2 large washers at each spot, = though from=20 what Lynn said, this may be more than enough to make a = difference.  =20
 
 
 At=20 the RPM you are talking about, I do not think there is an engine balance = problem. Even with a badly balanced engine, related vibrations did not = show up=20 below 4000RPM on my engine. 
 
I've had the engine up to about 5000, but = couldn't=20 richen the mixture enough to do much.  Still, aside from the odd = beat=20 frequency prop oscillation, I didn't notice any vibration.  Once = the engine=20 breaks out of the 2500-3100 rpm vibration pit, it's quite smooth. =20
 
As for the prop oscillation = thing, I've=20 come to believe that the prop pitch is way too high for the single = rotor. =20 I'm using a Warp Drive, 68" diameter, 3 blade prop, which is exactly the = same as=20 what I used on the RV-3 initially.   When I set the initial pitch, I = just=20 picked a round number, and set the tip angle at 15 degrees, since that = number=20 was stuck in my brain for some reason. 
 
Now=20 that I looked it up, I found that 15 degrees was the highest pitch I = ever tried=20 on the RV-3, and that was with the turbo, and 5 psi of boost.  The = 13B had=20 a 2.17 drive, rather than the 2.85, but still, me thinks I need to back = off to=20 about 10 degrees for now.  I even found notes about prop stalling = issues=20 when running that pitch on the RV-3, so with all the obstacles around = the prop=20 on the Kolb, I've almost certainly got some sort of asymmetric stalling = issues=20 going on.  I'm just sure this is causing the odd beat frequency = vibration,=20 and prop oscillation.   This will=20 be an easy thing to try, so I'll find out pretty soon if this is=20 it. 
 
Thanks,
Rusty (Gmail still=20 working) 
 
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