Return-Path: Received: from mailout1.pacific.net.au ([61.8.0.84] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 880654 for flyrotary@lancaironline.net; Sun, 17 Apr 2005 00:59:42 -0400 Received-SPF: none receiver=logan.com; client-ip=61.8.0.84; envelope-from=peon@pacific.net.au Received: from mailproxy1.pacific.net.au (mailproxy1.pacific.net.au [61.8.0.86]) by mailout1.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with ESMTP id j3H4wsJu031906 for ; Sun, 17 Apr 2005 14:58:54 +1000 Received: from ar1 (ppp2E3D.dyn.pacific.net.au [61.8.46.61]) by mailproxy1.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with SMTP id j3H4wpIn023025 for ; Sun, 17 Apr 2005 14:58:52 +1000 Message-ID: <004901c54309$27965f20$3d2e083d@ar1> From: "Leon" To: "Rotary motors in aircraft" References: Subject: End Clearancing of Rotors was Re: [FlyRotary] Re: New rotors, New housings Date: Sun, 17 Apr 2005 14:51:43 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0046_01C5435C.F87422A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_0046_01C5435C.F87422A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageHi Guys, Just to set the record straight, under normal operations (N.A. = engines), and sensible revs (under 8,500), there is little or no = cogent reason to do this mod. However, in full house race engines with BIG revs (10,000 + RPM), in = high boost engines (1 Bar + boost), or where "Giggle Gas" is used as in = Ken's case, it's not a bad idea. The main cause of the problem is crank = flex under high load conditions, which allows the rotors to cock in the = housing, and also wedge the oil film on the rotor journal. So it's = not a bad idea, and in fact I do both recommend it and practice it = myself in these apps.=20 Obviously, a centre bearing 2 piece crank will eliminate the crank = flexure. I have found over the years that 15 thou is more than = adequate, but 20 thou is quite OK.. Doesn't seem to affect compression = at all. I normally taper it away to nothing down to the outer oil = control ring groove on both sides, ap personal preference. Easily done = in a lathe, and I prefer to grind rather than machine (a tool post = grinder in the lathe is the go if yu have access to one) to avoid = interrupted cutting around the corner seal holes. That way, you get a = really nice finish without any chatter marks. Make sure the grooves are = de-burred if you do it. =20 There is an additional advantage. If you happen to lose oil pressure, = (even with a 2 piece centre bearing crank), the rotor has a natural = tendency to cock on the stationary gear due to lack of the oil film on = the crank journals. If you have clearanced the rotor tips, then there = is less likelihood that the corner & side seals will be swaged into = their grooves. In reality, loss of oil pressure is usually = catastrophic anyway, and the rotor usually needs to be replaced as the = raised lands (the rotor gear and the land on the opposite side sit proud = of the actual rotor faces) usually cop a hiding and end up cleaning up = below spec. My couple of Brass Razoos for today, Cheers, Leon ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Sunday, April 17, 2005 12:01 PM Subject: [FlyRotary] Re: New rotors, New housings That's off each side, Rob at Pineapple racing takes 20 thousandths = off each side but I figured the 15 should do it. Ken=20 Hi Ken, Why is it that you do this? I've never heard Leon, Lynn, or Bruce = mention this being necessary. =20 Cheers, Rusty (waiting for contractor season, so I can start shooting them) ------=_NextPart_000_0046_01C5435C.F87422A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Hi Guys,
 
Just to set the record straight,  = under normal=20 operations (N.A. engines),  and sensible revs (under 8,500),  = there is=20 little or no cogent reason to do this mod.
 
However,  in full house race = engines with BIG=20 revs (10,000 + RPM),  in high boost engines (1 Bar + boost),  = or where=20 "Giggle Gas" is used as in Ken's case, it's not a bad idea.  = The main=20 cause of the problem is crank flex under high load conditions,  = which=20 allows the rotors to cock in the housing,  and also wedge the oil = film on=20 the rotor journal.  So  it's not a bad idea,  and in fact = I do=20 both recommend it and practice it myself in these apps. =
 
Obviously, a centre bearing 2 piece = crank will=20 eliminate the crank flexure.  I have found over the years that 15 = thou is=20 more than adequate,  but 20 thou is quite OK..  Doesn't seem = to affect=20 compression at all.    I normally taper it away to nothing = down to the=20 outer oil control ring groove on both sides,  ap personal = preference. =20 Easily done in a lathe,  and I prefer to grind rather than=20 machine (a tool post grinder in the lathe is the go if yu have = access to=20 one) to avoid interrupted cutting around the corner seal = holes. That=20 way,  you get a really nice finish without any chatter marks.  = Make=20 sure the grooves are de-burred if you do it. 
 
There is an additional advantage.  = If you=20 happen to lose oil pressure,  (even with a 2 piece centre bearing = crank),=20  the rotor has a natural tendency to cock on the stationary gear = due to=20 lack of the oil film on the crank journals.  If you have clearanced = the=20 rotor tips,  then there is less likelihood that the corner & = side seals=20 will be swaged into their grooves.  In reality,  loss of oil = pressure=20 is usually catastrophic anyway,  and the rotor usually needs to be = replaced=20 as the raised lands (the rotor gear and the land on the opposite side = sit proud=20 of the actual rotor faces) usually cop a hiding and end up cleaning up = below=20 spec.
 
 
My couple of Brass Razoos for=20 today,
 
Cheers,
 
Leon
 
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Sunday, April 17, 2005 = 12:01=20 PM
Subject: [FlyRotary] Re: New = rotors, New=20 housings

   That's off each side, = Rob at=20 Pineapple racing takes 20 thousandths off each side but I figured the = 15=20 should do it.
    Ken 
 
Hi=20 Ken,
 
Why is it=20 that you do this?  I've never heard Leon, Lynn, or = Bruce=20 mention this being necessary.  
 
Cheers,
Rusty=20 (waiting for contractor season, so I can start shooting=20 them)
 
= ------=_NextPart_000_0046_01C5435C.F87422A0--