X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail24.syd.optusnet.com.au ([211.29.133.165] verified) by logan.com (CommuniGate Pro SMTP 5.0.6) with ESMTPS id 914438 for flyrotary@lancaironline.net; Thu, 05 Jan 2006 18:04:12 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.133.165; envelope-from=lendich@optusnet.com.au Received: from george (d58-105-133-79.dsl.nsw.optusnet.com.au [58.105.133.79]) by mail24.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id k05N3GOa003694 for ; Fri, 6 Jan 2006 10:03:20 +1100 Message-ID: <007101c6124c$385ab140$4f85693a@george> From: "george lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: [FlyRotary]Soapbox Warning! PSRU Ratios Date: Fri, 6 Jan 2006 09:03:18 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006E_01C612A0.0916BBF0" 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_006E_01C612A0.0916BBF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Tracy, No offence taken - just looking for answers and asking the people 'in = the know', al least you know people respect your opinion enough to ask. I could imagine it could be frustrating though! George ( down under) I thought maybe that's what you were driving at George, I just took = the opportunity to vent my frustration with the almost daily phone calls = I get asking "Why don't you do it this way ........." : ) No offense = meant to you at all. You and most everyone on this list have done = enough fabricating on your own to know how much goes into the design of = a flying widget. That sun gear spline does sound nice but notice that if the flange is = bolted to the damper and the oil seal runs on the smooth part of the = female spline, it looks like the oil is still going to leak out through = the spline interface. This can be worked out too but the problems = never end : ) Tracy ----- Original Message -----=20 From: george lendich=20 To: Rotary motors in aircraft=20 Sent: Wednesday, January 04, 2006 4:56 PM Subject: [FlyRotary] Re: [FlyRotary]Soapbox Warning! PSRU Ratios 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_006E_01C612A0.0916BBF0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Tracy,
No offence taken - just looking for answers and = asking the=20 people 'in the know', al least you know people respect your opinion = enough to=20 ask.
I could imagine it could be frustrating=20 though!
George ( down under)
 
I thought maybe that's what you were driving at George, I just = took the=20 opportunity to vent my frustration with the almost daily phone calls I = get=20 asking "Why don't you do it this way ........." : ) No = offense meant=20 to you at all.  You and most everyone on this list have done = enough=20 fabricating on your own to know how much goes into the design of = a flying=20 widget.
 
That sun gear spline does sound nice but notice that if the = flange=20 is bolted to the damper and the oil seal runs on the smooth part of = the female=20 spline, it looks like the oil is still going to leak out through = the=20 spline interface.   This can be worked out too but the = problems=20 never end : )
 
Tracy
----- Original Message -----
From: george lendich
To: Rotary motors in = aircraft=20
Sent: Wednesday, January 04, = 2006 4:56=20 PM
Subject: [FlyRotary] Re:=20 [FlyRotary]Soapbox Warning! PSRU Ratios

 
Thanks Tracy,
I wasn't advocating that you change your = current=20 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=20 but haven't found one that has all the attributes on the 'wish = list'. The=20 straight cut gears and the splined sun gear were way up there on the = "wish=20 list', BTW the female splined flange has a neck sufficiently long = for a=20 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=20 it's probably going in the wrong direction for most. I have=20 also that 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=20 evaluating different configurations.
Thanks again!
George ( down under)
 
Hi George, glad you asked, gives me an opportunity to answer it = once=20 for 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=20 the production procedures (this is no small thing) and = replacing all=20 this 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=20 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=20 does it give us?  It has a smaller diameter ring gear (4.4" = vs 5.0")=20 narrower gears (about 3/4" vs 7/8") and one less = planet.  On=20 paper, this looks like a minus, not a plus.  The availability = of=20 straight cut gears is a possible bonus but on the other hand, I = have not=20 had any problem dealing with the helical gear thrust so=20 far. 
 
The splined sun gear might be nice but so far we are paying a = pretty=20 high price for it.  A lot of other factors need to be=20 considered.  For instance, How do you isolate the oil in the = gear box=20 when using that mating splined part?  Is there a place to put = an oil=20 seal?  There are literally hundreds of questions like this = that must=20 be answered during the course of designing a gear = reduction=20 drive. 
 
As far as the ratio goes, 2.85 : 1 is actually a bit higher = than=20 optimum for most applications.  Going even higher is the = wrong=20 direction.  Note that I said "most applications".  There = will of=20 course be some that would favor a higher one.  A detailed = discussion=20 of this would be interesting but is way more involved than I=20 can detail in an email message.  But, to summarize, = I=20 believe fuel economy, engine life, and proper matching with a = suitable=20 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=20 all over again.  I give the Ford guys as much = credit as the=20 Dodge boys -  Zero.
 
I know Paul L. pushes for more power at every turn (higher = rpm=20 (requiring higher ratios), P porting, etc) but I think this = focus is=20 counterproductive in too many other areas.  I'm more in tune = with=20 Richard 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=20 the 2.17 which is still in production.  There are plenty of=20 applications where the 2.17 is clearly a better choice than the=20 2.85.  There are still times when I would prefer the 2.17 on = my own=20 plane.  Some of the reasons are subtle and not=20 quantifiable.  I like the BMW better than the Chevy I drove = but I=20 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=20 5:56 PM
Subject: [FlyRotary] PSRU = Ratios

A question for = Tracy.
What problems would you = envisage using a=20 3.21 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 (=20 overdrive).
There are two 5 planet = arrangements, one=20 with angle cut ( opposite to the Ford unit) whereby the thrust=20 is between the sun gear and planet ( internal thrust gear=20 arrangement).
The other is a straight = cut 5 planet=20 arrangement ( no thrust).
 
The beauty of this planetary is = that the=20 sun gear has a spline at the aft end with a matching female = splined=20 flange ( for 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=20 the Dodge units are superior to the Ford units, = however that would=20 have to be confirmed. 
 
Originally you were opposed to = going from=20 the 2.17 to 2.85 for a number of reasons - can quite remember = why? Was=20 it because of higher RPM ( engine workload)? overspeeding the = water pump=20 and alternator? Anything else ?
 
What problems do you envisage = with a 3.21:1=20 ratio?
George ( down=20 = under)
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