X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop-Diagnostic: (direct reply)\eX-PolluStop-Score: 0.00\eX-PolluStop: Scanned with Niversoft PolluStop 2.1 RC1, http://www.niversoft.com/pollustop Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c4) with ESMTP id 868621 for flyrotary@lancaironline.net; Thu, 14 Apr 2005 10:34:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.res.rr.com [24.74.185.127]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j3EEXiLw026108 for ; Thu, 14 Apr 2005 10:33:45 -0400 (EDT) Message-ID: <003101c540fe$fb1a1ab0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Rx-8 Rotors Date: Thu, 14 Apr 2005 10:33:52 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002E_01C540DD.73D8B820" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_002E_01C540DD.73D8B820 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Doug, Some good thoughts and questions, of which I would like to know the = answers to as well. I believe the reason the experts are recommending = milling the RX-8 rotors for the older seals (when used in the older = rotor housings with peripheral exhausts) is that the RX-8 seal was not = designed to withstand the forces of crossing the exhaust port (in the = Peripheral wall) opening unsupported. Its rather skinny and long. = Mazdatrix reported the RX-8 seals warped as a consequence of the the hot = exhaust gas blowing over them and primarily the lack of wall support at = the exhaust opening(on the older housings). The combination of the = additional heat and lack of wall support appears to be more than the 8 = seal can take. However, I am in basic agreement with you why machine the rotor when = perhaps a new/modified seal is the answer. I want to check with Tracy = Crook since his seals are reportedly 800% stronger than stock apex seals = to see whether the seals could be machined down/created so that they fit = in the RX-8 rotor standard apex slot and still be strong enough - say = 300% stronger than stock {:>). Since they are not made of typical "gray = iron" alloy that the stock and most other seals are made and chill/case = hardened, they may be amenable to machining. Yes, having airports scattered around in just about every county and = sometimes three or more in a county, the geography is much kinder to = engine-out excursions here on the east coast. Fly High, Glide long! = Better yet, keep running on both rotors. Ed A ----- Original Message -----=20 From: Shearbond@aol.com=20 To: Rotary motors in aircraft=20 Sent: Thursday, April 14, 2005 10:10 AM Subject: [FlyRotary] Rx-8 Rotors So.....since the rotors weigh the same within measurement error, the = ability to rev to the 9,000s range vs. 7,000s range is not related to = the orbiting mass of the rotor. (Note: the motion is NOT truly = circular, it is an epicycloid path that the center of mass of the rotor = takes. That 10 lb. rotor flops around plenty (technical term) and 10 = lb. is lots heavier than an aluminum piston! It is apparent from an article on the "other" site, that the wall = thicknesses and casting detail are lots more refined on the RX8 rotors = than on earlier models...for more uniform and desirable heat transfer = and uniformity.....oil cooling the rotor, etc. The mass being basically the same, it becomes a high probability that = since centripetal force is F =3D (Mass x rotational velocity = squared)/radius of rotation, {F=3D(m x w^2)/r}, it must be the weight of = the seals themselves that are the critical element? The force at 8,500 = vx. 6,500 is (8.5/6.5) squared or 1.71 times greater. Might this be why = seal wear on the original seals goes up substantially at around 6,500 = rpm? Tell me....why would one increase the depth of the seal groove of an = RX8 rotor to allow a heavier seal???? On the RX8, 3.25mm/9.5mm =3D> = approx. 34% reduction in apex seal mass!! A lighter seal means a whole = lot less force of the seal against the housing at 8,500 rpm!! Anyone = want to go back to old seals and rev to 8,500 rpm? =20 Note: the seal force against the housing at 8,500 rpm on the RX8 is = still higher than the old seal at 6,500.... (.66 x 1.71 =3D 1.129). Not = much more, but there are probably even more very small details that we = are not at first glance able to know and understand? Seal = material/housing material compatability is probably one significant = factor?? (I used 9,000 vs. 7,000 and the numbers still come out about = 10% higher seal force on the RX8, even with the lighter seals.) =20 Having been an R&D engineer at FoMoCo, it is hard to explain to most = persons the creativity, detail, imagination, trial and testing and = testing and testing and testing and ...... which goes into making an = engine acceptable for production in quantities of XXX,XXX's and higher. = (One simply can't be wrong...it could bankrupt even the largest OEM.) = And....those Mazda engineers have done what many OEM's gave up on many = years ago. How? Through their persistence and incredible insight into = the issues. Before one gets the wire EDM out and starts going counter to what = Mazda no doubt spent many $$$$ (more than all of our annual incomes put = together??) on how to increase HP in an RX8, more information is needed = before we start mixing and matching just because the parts will fit. I = know we are experimenters here, but lives of some who may not understand = the "physics" limitations will ultimately be at stake. Above all: Just because something works for 100 miles in a sprint = race DOES NOT mean it will work while hummmming along for 5 hours at a = crack at 75-80% max. HP on a cross-country over and over and over = again....hopefully. So far, my Lyc is a piece of 30's era design and = materials...but it has run for 2,000 hours (350,000 miles) at 75-100% = without fail!! Most of us aren't as lucky as Ed and his "on airport" emergency = landings. Perhaps it is that his green carpet (Carolina's) is lots more = friendly than our granite peaks out here? Doug in Colorado ------=_NextPart_000_002E_01C540DD.73D8B820 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Doug,
 
Some good thoughts and questions, of which I would like to know the = answers=20 to as well.  I believe the reason the experts are recommending = milling the=20 RX-8 rotors for the older seals (when used in the older rotor housings = with=20 peripheral exhausts) is that the RX-8 seal was not designed to withstand = the=20 forces of crossing the exhaust port (in the Peripheral wall) opening=20 unsupported. Its rather skinny and long.  Mazdatrix reported = the RX-8=20 seals warped as a consequence of the the hot exhaust gas blowing over = them and=20 primarily the lack of wall support at the exhaust opening(on the older=20 housings).  The combination of the additional heat and lack of wall = support=20 appears to be more than the 8 seal can take.
 
However, I am in basic  agreement with you why machine the = rotor when=20 perhaps a new/modified seal is the answer.  I want to check with = Tracy=20 Crook since his seals are reportedly 800% stronger than stock apex seals = to see=20 whether the seals could be machined down/created so that they fit in the = RX-8=20 rotor  standard apex slot and still be strong enough - say 300% = stronger=20 than stock {:>).  Since they are not made of typical "gray iron" = alloy=20 that the stock and most other seals are made and chill/case hardened, = they may=20 be amenable to machining.
 
Yes, having airports scattered around in just about every county = and=20 sometimes three or more in a county, the geography is much kinder to = engine-out=20 excursions here on the east coast.  Fly High, Glide long!  = Better yet,=20 keep running on both rotors.
 
Ed A
 
 
----- Original Message -----
From:=20 Shearbond@aol.com
Sent: Thursday, April 14, 2005 = 10:10=20 AM
Subject: [FlyRotary] Rx-8 = Rotors

So.....since the rotors weigh the same within measurement error, = the=20 ability to rev to the 9,000s range vs. 7,000s range is not related to = the=20 orbiting mass of the rotor.  (Note: the motion is NOT truly = circular, it=20 is an epicycloid path that the center of mass of the rotor = takes.  That=20 10 lb. rotor flops around plenty (technical term) and 10 lb. is lots = heavier=20 than an aluminum piston!
 
It is apparent from an article on the "other" site, that the wall = thicknesses and casting detail are lots more refined on the RX8=20 rotors than on earlier models...for more uniform and desirable = heat=20 transfer and uniformity.....oil cooling the rotor, etc.
 
The mass being basically the same, it becomes a high probability = that=20 since centripetal force is F =3D (Mass x rotational velocity=20 squared)/radius of rotation, {F=3D(m x w^2)/r}, it must be = the weight=20 of the seals themselves that are the critical=20 element?  The force at 8,500 vx. 6,500 is (8.5/6.5) squared or = 1.71 times=20 greater.  Might this be why seal wear on the original seals goes = up=20 substantially at around 6,500 rpm?
 
Tell me....why would one increase the depth of the seal groove of = an RX8=20 rotor to allow a heavier seal????  On the RX8, 3.25mm/9.5mm = =3D>=20 approx. 34% reduction in apex seal mass!!  A lighter = seal means=20 a whole lot less force of the seal against the housing at 8,500 = rpm!! =20 Anyone want to go back to old seals and rev to 8,500 rpm? 
 
Note:  the seal force against the housing at 8,500 rpm on = the RX8 is=20 still higher than the old seal at 6,500.... (.66 x 1.71 =3D = 1.129).  Not=20 much more, but there are probably even more very small details = that we=20 are not at first glance able to know and understand?  Seal=20 material/housing material compatability is probably one significant=20 factor??  (I used 9,000 vs. 7,000 and the numbers still come out = about=20 10% higher seal force on the RX8, even with the lighter seals.)  =
 
Having been an R&D engineer at FoMoCo, it is hard to explain = to most=20 persons the creativity, detail, imagination, trial and testing and = testing and=20 testing and testing and ...... which goes into making an engine=20 acceptable for production in quantities of XXX,XXX's and higher.  = (One=20 simply can't be wrong...it could bankrupt even the largest OEM.)  = And....those Mazda engineers have done what many OEM's gave up on many = years=20 ago.  How?  Through their persistence and incredible insight = into=20 the issues.
 
Before one gets the wire EDM out and starts going counter to what = Mazda=20 no doubt spent many $$$$ (more than all of our annual incomes put = together??) on how to increase HP in an RX8, more information is = needed before=20 we start mixing and matching just because the parts will = fit.  I=20 know we are experimenters here, but lives of some who may not = understand the=20 "physics" limitations will ultimately be at stake.
 
Above all:  Just because something works for 100 miles in a = sprint=20 race DOES NOT mean it will work while hummmming = along=20 for 5 hours at a crack at 75-80% max. HP on a cross-country over and = over and=20 over again....hopefully.  So far, my Lyc is a piece of 30's era = design=20 and materials...but it has run for 2,000 hours (350,000 miles) at = 75-100%=20 without fail!!
 
Most of us aren't as lucky as Ed and his "on airport" emergency=20 landings.  Perhaps it is that his green carpet = (Carolina's) is lots=20 more friendly than our granite peaks out here?
 
Doug in Colorado
------=_NextPart_000_002E_01C540DD.73D8B820--