X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imf24aec.mail.bellsouth.net ([205.152.59.72] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTP id 2086372 for flyrotary@lancaironline.net; Tue, 05 Jun 2007 22:16:24 -0400 Received-SPF: none receiver=logan.com; client-ip=205.152.59.72; envelope-from=rusty@radrotary.com Received: from ibm68aec.bellsouth.net ([65.6.194.9]) by imf24aec.mail.bellsouth.net with ESMTP id <20070606021548.OITY9226.imf24aec.mail.bellsouth.net@ibm68aec.bellsouth.net> for ; Tue, 5 Jun 2007 22:15:48 -0400 Received: from rd ([65.6.194.9]) by ibm68aec.bellsouth.net with ESMTP id <20070606021545.OCPS16465.ibm68aec.bellsouth.net@rd> for ; Tue, 5 Jun 2007 22:15:45 -0400 From: "Russell Duffy" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Single rotor video Date: Tue, 5 Jun 2007 21:15:47 -0500 Message-ID: <016001c7a7e0$989a7240$6e01a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0161_01C7A7B6.AFC46A40" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6822 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 Importance: Normal Thread-Index: AcenkXDsuDF1dFWzTRuwn+rYEhXtfQASoQiQ In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_0161_01C7A7B6.AFC46A40 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Greetings, =20 Thanks for all the comments, but I do think some of you are getting a = bit ahead of me on this :-) The following are mostly random thoughts. =20 The phenomenon is really amazing to me, but until more combinations are tested, I'm not sure if it's even a problem. My gut feeling is that it happens to some extent with any flexible prop, and requires some = instability in thrust to set it off. Low rpms and changing speeds seem to set it = off for sure. IVO props are more flexible, and have an even worse problem, = but the only caution is to allow 5" clearance at the tips of the IVO so it = won't hit anything. Even with that clearance, my old IVO on the Kolb hit the = back of the fuselage cage on startup one day. They flex a LOT. =20 =20 Common sense would dictate that too much of this flexing is clearly not good, and a line will have to be drawn before prop, or engine damage is done, but who can say where that line needs to be without a ton of = testing? =20 A single rotor Mazda (without a flywheel) has to be about the worst = case, because it's got a big powerful combustion chamber. Rotax had plenty of single cylinder engines, but at most, they were half the size of the = single Mazda chamber. By the time any "normal" engine gets to the displacement = of the single rotor Mazda, it's got at least two cylinders to help smooth things out. Clearly, what we need is a 2 or 3 rotor engine that's sized = to make an easy 100 HP. =20 =20 My goal will be to re-video the current configuration, perhaps with a yardstick or some other markings in the picture for scale. I'll zoom it more to get just the engine and prop, for more detail. I might even use = the real video camera instead of my Cannon PowerShot 3 :-) I'll video set = rpms from about 2000 to maybe 5000, depending on how brave I feel about my trailer stand. Not sure when this will happen, as I'll be out of town = for a few days getting dual in a similar gyro (nice try Lynn ). =20 =20 I smell fajitas, and my beer is empty. Gotta go :-)=20 =20 Rusty =20 ------=_NextPart_000_0161_01C7A7B6.AFC46A40 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message
Greetings,
 
Thanks for=20 all the comments, but I do think some of you are getting a bit ahead of = me on=20 this :-)  The following are mostly random = thoughts.
 
The=20 phenomenon is really amazing to me, but until more combinations are = tested, I'm=20 not sure if it's even a problem.  My gut feeling is that it happens = to some=20 extent with any flexible prop, and requires some instability in thrust = to set it=20 off.  Low rpms and changing speeds seem to set it off for = sure.  IVO props are more flexible, and have an even worse = problem,=20 but the only caution is to allow 5" clearance at the tips of the = IVO so it=20 won't hit anything.  Even with that clearance, my old IVO on = the Kolb=20 hit the back of the fuselage cage on startup one = day.  They flex=20 a LOT. 
 
Common sense=20 would dictate that too much of this flexing is clearly not = good, and a line=20 will have to be drawn before prop, or engine damage is done, but = who can=20 say where that line needs to be without a ton of=20 testing?    
 
A single=20 rotor Mazda (without a flywheel) has to be about the worst case,=20 because it's got a big powerful combustion = chamber.  Rotax=20 had plenty of single cylinder engines, but at most, they were half = the size=20 of the single Mazda chamber.  By the time any "normal" engine = gets to=20 the displacement of the single rotor Mazda, it's got at least two = cylinders to=20 help smooth things out.  Clearly, what we need is a 2 or 3 rotor = engine=20 that's sized to make an easy 100 HP. 
 
My goal will=20 be to re-video the current configuration, perhaps with a yardstick or = some other=20 markings in the picture for scale.  I'll zoom it more to get just = the=20 engine and prop, for more detail.  I might even use the real video = camera=20 instead of my Cannon PowerShot 3 :-)  I'll video set rpms from = about 2000=20 to maybe 5000, depending on how brave I feel about my trailer=20 stand.  Not sure when this will happen, as I'll be out = of town=20 for a few days getting dual in a similar gyro (nice try Lynn=20 <g>).  
 
I smell=20 fajitas, and my beer is empty.  Gotta go = :-) 
 
Rusty
 
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