X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [65.54.250.73] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 5.0.6) with ESMTP id 912082 for flyrotary@lancaironline.net; Tue, 03 Jan 2006 23:06:03 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.250.73; envelope-from=lors01@msn.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Tue, 3 Jan 2006 20:05:18 -0800 Message-ID: Received: from 4.171.174.78 by BAY115-DAV1.phx.gbl with DAV; Wed, 04 Jan 2006 04:05:18 +0000 X-Originating-IP: [4.171.174.78] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary]Soapbox Warning! PSRU Ratios Date: Tue, 3 Jan 2006 23:05:14 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00F6_01C610BA.27E52D10" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0011.1703 Seal-Send-Time: Tue, 3 Jan 2006 23:05:14 -0500 X-OriginalArrivalTime: 04 Jan 2006 04:05:18.0978 (UTC) FILETIME=[13584E20:01C610E4] This is a multi-part message in MIME format. ------=_NextPart_000_00F6_01C610BA.27E52D10 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi George, glad you asked, gives me an opportunity to answer it once for = everybody. If you mean 'what problem would it be for me' the answer is "No problem = at all". Except for scrapping every part of the current design, = scrapping all the tooling developed for it, scrapping all the = production procedures (this is no small thing) and replacing all this = with new stuff. Obviously, there has to be a good reason to do this to make it worth = while. It has to solve an existing problem (are there any?), = significantly improve performance (would it?) or reduce cost enough to = justify all the work and expense of changing (does it?). I'm sure that Dodge gear set is a fine piece of hardware but what does = it give us? It has a smaller diameter ring gear (4.4" vs 5.0") narrower = gears (about 3/4" vs 7/8") and one less planet. On paper, this looks = like a minus, not a plus. The availability of straight cut gears is a = possible bonus but on the other hand, I have not had any problem dealing = with the helical gear thrust so far.=20 The splined sun gear might be nice but so far we are paying a pretty = high price for it. A lot of other factors need to be considered. For = instance, How do you isolate the oil in the gear box when using that = mating splined part? Is there a place to put an oil seal? There are = literally hundreds of questions like this that must be answered during = the course of designing a gear reduction drive. =20 As far as the ratio goes, 2.85 : 1 is actually a bit higher than optimum = for most applications. Going even higher is the wrong direction. Note = that I said "most applications". There will of course be some that = would favor a higher one. A detailed discussion of this would be = interesting but is way more involved than I can detail in an email = message. But, to summarize, I believe fuel economy, engine life, and = proper matching with a suitable prop would suffer with a higher ratio. Anecdotal data from people in the auto transmission industry has been = contradictory at best. It's the Chevy vs Ford vs Mopar thing all over = again. I give the Ford guys as much credit as the Dodge boys - Zero. I know Paul L. pushes for more power at every turn (higher rpm = (requiring higher ratios), P porting, etc) but I think this focus is = counterproductive in too many other areas. I'm more in tune with = Richard Vangrunsvan's goal - Total Performance. You also asked why I was previously opposed to changing from 2.17 to = 2.85. Note that I did not change. The 2.85 is in addition to the 2.17 = which is still in production. There are plenty of applications where = the 2.17 is clearly a better choice than the 2.85. There are still = times when I would prefer the 2.17 on my own plane. Some of the reasons = are subtle and not quantifiable. I like the BMW better than the Chevy I = drove but I couldn't give you any hard reasons for it. Tracy (now stepping off soap box) ----- Original Message -----=20 From: george lendich=20 To: Rotary motors in aircraft=20 Sent: Tuesday, January 03, 2006 5:56 PM Subject: [FlyRotary] PSRU Ratios A question for Tracy. What problems would you envisage using a 3.21 ratio instead of the = 2.85. One of the Lads on the other site has found this 'U-beaut' Planetary = out of a Cummings Diesel ( overdrive). There are two 5 planet arrangements, one with angle cut ( opposite to = the Ford unit) whereby the thrust is between the sun gear and planet ( = internal thrust gear arrangement). The other is a straight cut 5 planet arrangement ( no thrust). The beauty of this planetary is that the sun gear has a spline at the = aft end with a matching female splined flange ( for bolting to the = damper plate). The ring gear is externally notched as in the Ford 2.17. The planet housing is similar in design and size to the Ford 2.85. Advice from people in the industry are that the Dodge units are = superior to the Ford units, however that would have to be confirmed.=20 Originally you were opposed to going from the 2.17 to 2.85 for a = number of reasons - can quite remember why? Was it because of higher RPM = ( engine workload)? overspeeding the water pump and alternator? Anything = else ? What problems do you envisage with a 3.21:1 ratio? George ( down under) ------=_NextPart_000_00F6_01C610BA.27E52D10 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi George, glad you asked, gives me an opportunity to answer it = once for=20 everybody.
 
 If you mean 'what problem would it be for me' the answer is = "No=20 problem at all".  Except for scrapping every part of the = current=20 design, scrapping all the tooling developed for it,  scrapping all = the=20 production procedures (this is no small thing) and replacing all = this with=20 new stuff.
 
Obviously, there has to be a good reason to do this to make it = worth=20 while.  It has to solve an existing problem  (are there any?), = significantly improve performance (would it?) or reduce cost enough = to=20 justify all the work and expense of changing (does it?).
 
I'm sure that Dodge gear set is a fine piece of hardware but what = does it=20 give us?  It has a smaller diameter ring gear (4.4" vs 5.0") = narrower gears=20 (about 3/4" vs 7/8") and one less planet.  On paper, this = looks like a=20 minus, not a plus.  The availability of straight cut gears is a = possible=20 bonus but on the other hand, I have not had any problem dealing = with the=20 helical gear thrust so far. 
 
The splined sun gear might be nice but so far we are paying a = pretty high=20 price for it.  A lot of other factors need to be considered.  = For=20 instance, How do you isolate the oil in the gear box when using that = mating=20 splined part?  Is there a place to put an oil seal?  There are = literally hundreds of questions like this that must be = answered during the=20 course of designing a gear reduction drive. 
 
As far as the ratio goes, 2.85 : 1 is actually a bit higher than = optimum=20 for most applications.  Going even higher is the wrong = direction. =20 Note that I said "most applications".  There will of course be some = that=20 would favor a higher one.  A detailed discussion of this would be=20 interesting but is way more involved than I can detail in an email=20 message.  But, to summarize, I believe fuel economy, engine = life, and=20 proper matching with a suitable prop would suffer with a higher = ratio.
 
Anecdotal data from people in the auto transmission industry has = been=20 contradictory at best.  It's the Chevy vs Ford vs Mopar thing = all over=20 again.  I give the Ford guys as much credit as the Dodge=20 boys -  Zero.
 
I know Paul L. pushes for more power at every turn (higher rpm = (requiring=20 higher ratios), P porting, etc) but I think this focus is = counterproductive=20 in too many other areas.  I'm more in tune with Richard = Vangrunsvan's=20 goal  -  Total Performance.
 
You also asked why I was previously opposed to changing from 2.17 = to=20 2.85.  Note that I did not change.  The 2.85 is in addition to = the=20 2.17 which is still in production.  There are plenty of = applications where=20 the 2.17 is clearly a better choice than the 2.85.  There are still = times=20 when I would prefer the 2.17 on my own plane.  Some of the = reasons are=20 subtle and not quantifiable.  I like the BMW better than the Chevy = I drove=20 but I couldn't give you any hard reasons for it.
 
Tracy (now stepping off soap box)
----- Original Message -----
From: george lendich
To: Rotary motors in = aircraft
Sent: Tuesday, January 03, 2006 = 5:56=20 PM
Subject: [FlyRotary] PSRU = Ratios

A question for Tracy.
What problems would you envisage = using a 3.21=20 ratio instead of the 2.85.
 
One of the Lads on the other site has = found this=20 'U-beaut' Planetary out of a Cummings Diesel ( = overdrive).
There are two 5 planet arrangements, = one with=20 angle cut ( opposite to the Ford unit) whereby the thrust = is between the=20 sun gear and planet ( internal thrust gear arrangement).
The other is a straight cut 5 = planet=20 arrangement ( no thrust).
 
The beauty of this planetary is that = the sun gear=20 has a spline at the aft end with a matching female splined flange ( = for=20 bolting to the damper plate).
 
The ring gear is externally notched = as in=20 the Ford  2.17.
The planet housing is similar in = design and size=20 to the Ford 2.85.
 
Advice from people in the industry = are that the=20 Dodge units are superior to the Ford units, however that would = have to be=20 confirmed. 
 
Originally you were opposed to going = from the=20 2.17 to 2.85 for a number of reasons - can quite remember why? Was it = because=20 of higher RPM ( engine workload)? overspeeding the water pump and = alternator?=20 Anything else ?
 
What problems do you envisage with a = 3.21:1=20 ratio?
George ( down=20 under)
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