X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail11.syd.optusnet.com.au ([211.29.132.192] verified) by logan.com (CommuniGate Pro SMTP 5.0.6) with ESMTPS id 912894 for flyrotary@lancaironline.net; Wed, 04 Jan 2006 16:57:15 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.192; envelope-from=lendich@optusnet.com.au Received: from george (d58-105-142-38.dsl.nsw.optusnet.com.au [58.105.142.38]) by mail11.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id k04LuMOA028187 for ; Thu, 5 Jan 2006 08:56:24 +1100 Message-ID: <003201c61179$b46e2470$268e693a@george> From: "george lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: [FlyRotary]Soapbox Warning! PSRU Ratios Date: Thu, 5 Jan 2006 07:56:23 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002F_01C611CD.856C1A20" 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 This is a multi-part message in MIME format. ------=_NextPart_000_002F_01C611CD.856C1A20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Tracy, I wasn't advocating that you change your current manufacturing and = models. I was more or less looking for problems associated with MY use = of a 3.21 Ratio. I guess, deep down, I would prefer a 2.5 ratio myself but haven't found = one that has all the attributes on the 'wish list'. The straight cut = gears and the splined sun gear were way up there on the "wish list', BTW = the female splined flange has a neck sufficiently long for a bearing and = a seal. It all looked too good to be true - BUGGER! Good luck to Ken if he can use it, but like you said it's probably going = in the wrong direction for most. I have also that similar advice from = another valued source. I do appreciate you going to the trouble, but from my perspective it = doesn't hurt to keep looking at, and evaluating different = configurations. Thanks again! George ( down under) 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_002F_01C611CD.856C1A20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Thanks Tracy,
I wasn't advocating that you change your current = manufacturing and models. I was more or less looking for problems = associated=20 with MY use of a 3.21 Ratio.
 
I guess, deep down, I would prefer a 2.5 ratio = myself but=20 haven't found one that has all the attributes on the 'wish list'. The = straight=20 cut gears and the splined sun gear were way up there on the "wish list', = BTW the=20 female splined flange has a neck sufficiently long for a bearing and a = seal. It=20 all looked too good to be true - BUGGER!
 
Good luck to Ken if he can use it, but like you = said it's=20 probably going in the wrong direction for most. I have = also that=20 similar advice from another valued source.
 
I do appreciate you going to the trouble, but = from my=20 perspective it doesn't hurt to keep looking at, and = evaluating different=20 configurations.
Thanks again!
George ( down under)
 
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=20 with 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?),=20 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=20 gears (about 3/4" vs 7/8") and one less planet.  On paper, = this=20 looks like a minus, not a plus.  The availability of straight cut = gears=20 is a possible bonus but on the other hand, I have not had any=20 problem dealing with the 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=20 literally hundreds of questions like this that must be = answered during=20 the 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 = interesting but is way more involved than I can detail in an = email=20 message.  But, to summarize, I believe fuel economy, engine = life,=20 and proper matching with a suitable prop would suffer with a higher=20 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=20 over 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=20 counterproductive in too many other areas.  I'm more in tune with = Richard=20 Vangrunsvan's 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=20 where the 2.17 is clearly a better choice than the 2.85.  There = are still=20 times when I would prefer the 2.17 on my own plane.  Some of the=20 reasons are subtle and not quantifiable.  I like the BMW = better than=20 the Chevy I drove 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=20
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=20 this '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=20 the 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=20 gear 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=20 size 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=20 be 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=20 because of higher RPM ( engine workload)? overspeeding the water = pump and=20 alternator? Anything else ?
 
What problems do you envisage with = a 3.21:1=20 ratio?
George ( down=20 under)
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