X-Virus-Scanned: clean according to Sophos on Logan.com From: "Neil Unger" Received: from nskntmtas02p.mx.bigpond.com ([61.9.168.140] verified) by logan.com (CommuniGate Pro SMTP 6.1.5) with ESMTPS id 8002201 for flyrotary@lancaironline.net; Sat, 19 Sep 2015 18:42:06 -0400 Received-SPF: pass receiver=logan.com; client-ip=61.9.168.140; envelope-from=neil.unger@bigpond.com Received: from nskntcmgw07p ([61.9.169.167]) by nskntmtas02p.mx.bigpond.com with ESMTP id <20150919224130.MEII23517.nskntmtas02p.mx.bigpond.com@nskntcmgw07p> for ; Sat, 19 Sep 2015 22:41:30 +0000 Received: from UserPC ([121.217.215.21]) by nskntcmgw07p with BigPond Outbound id KAhR1r00J0UGcWp01AhSqk; Sat, 19 Sep 2015 22:41:30 +0000 X-Authority-Analysis: v=2.0 cv=Vsyh8pKn c=1 sm=1 a=VqSvK6BrPH0jg+6KSzMZwQ==:17 a=1IlZJK9HAAAA:8 a=Ia-xEzejAAAA:8 a=7g1VtSJxAAAA:8 a=_JQ93bizIeSEZBVxVdsA:9 a=QEXdDO2ut3YA:10 a=Qa1je4BO31QA:10 a=iZRZStE_Lc5aOQpr:21 a=tE0k1vZnWP1QfnvD:21 a=4PR2P7QzAAAA:8 a=A1UnXz347Dc0RD2AD2oA:9 a=_W_S_7VecoQA:10 a=VqSvK6BrPH0jg+6KSzMZwQ==:117 Message-ID: <9490F5D677844A38BFCF00F0A377AC28@UserPC> To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: New psru Date: Sun, 20 Sep 2015 08:41:24 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006A_01D0F380.21E25970" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3555.308 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3555.308 This is a multi-part message in MIME format. ------=_NextPart_000_006A_01D0F380.21E25970 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Tracy, Have hear many whispers about your =E2=80=9Cinflexible=E2=80=9D = coupling, but just the thought makes me nervous. Most of the money on a = coupling is in the splined block that the engine drives, the extra Flex = part is not a lot extra. Have al;ready has two made and destroyed both = in testing but the Poly and rubber (one each) survived. The poly is by = far the cheapest, but solid???? I just don=E2=80=99t feel right. Neil. = From: Tracy=20 Sent: Saturday, September 19, 2015 10:09 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: New psru Looks like very nice work Neil, glad you picked up the ball and ran. I = had the same comment as Charlie but as long as you get a suitable prop = the 3.12 will work. Only down side is I think the minimum BSFC 'sweet = spot' of the rotary (about 5000 - 5500 rpm) may be below the usable = cruise settings if propped for 8500 with a fixed pitch prop. Not a big = deal though. When looking at my flying expenses, fuel turns out to be = about the cheapest item :-) I would urge you to investigate 'going naked' with the damper. My = direct coupler version is at least as smooth as the rubber coupled = damper version. Only downside is it may not be suitable for metal props = but I doubt you could find a suitable metal one for 3.12 ratio anyway. Keep up the good work, Tracy Sent from my iPad On Sep 18, 2015, at 09:15, Charlie England = wrote: I understand about debugging what you've got, before going off in a = new direction. That's why I hated to bring it up now. :-) The prop doesn't know how fast the engine is turning; it just knows = how fast *it* is turning, and how fast it's moving through the air. I = think that the problems start when the prop carver gets out of his = comfort zone, which is 2700 design rpm and around 72" maximum diameter = (usually less). When diameter goes up to 74"-76" and design rpm starts = to drop, they seem to get a bit confused. For those of us who never = expect to exceed 7500 rpm, with cruise down around 5500-6000, a 3.12 = ratio would mean prop at 2400 rpm max, and around 1900 at cruise. = Nothing wrong with that if we could swing a 7 foot diameter prop, but = with small, short legged a/c, you just can't do it.=20 I couldn't find anything in my old emails about the prop you had = problems with. What were its specs & mfgr? Was the 6000 rpm static, or = full throttle in flight at low altitude? Did you ever get your engine on = a dyno? I know what Lamar claimed for his p-port Renesis, but if those = were 'corrected' dyno numbers, they are pretty useless for real world = flying at higher than sea level and anything above 'standard day' = temperatures (which almost never happens). 250 HP seems pretty = optimistic for a normally aspirated 2 rotor actually flying in an a/c, = but I hope you can get it working. I've been very tempted to find = another Renesis core & send the housings out to get them p-ported, & if = you're successful, you just might push me over the edge... Charlie On 9/17/2015 11:17 PM, Neil Unger wrote: Charlie, As usual anything is possible. The 2.85 ratio is easier = to alter the gear set , but by the time the =E2=80=9Clittle=E2=80=9D = mods are done the cost climbs yet again. May look at the possibility as = all the drawings are done and alterations are now much simpler. Will = get the bugs out of this one first. Most prop makers that I went to = just do not want to hear =E2=80=9Crotary=E2=80=9D. The revs are there = but the torque is not compared to a lyc. Much to learn in this area. = Regards, neil. From: Charlie England=20 Sent: Friday, September 18, 2015 12:44 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: New psru Hi Neil,=20 Congrats on your progress; it looks nice. I like the idea of being = able to source some of the parts locally, given that international = shipping can cost more than a lot of parts.=20 The damper issue is a real bummer. IIRC, Tracy's been running a = later version of his 2.85 directly coupled to an aluminum racing = flywheel. One or two others have used light weight steel flywheels, but = I think they were still using Tracy's damper mechanism, which doesn't = look too complicated to build with precision machine tools that you = obviously have access to. I know you'll hate to hear this question, but....are there = provisions to use the 2.85 ratio in your design? The reason I ask is = that many of us have no desire to turn the engine beyond 7500 rpm, and = that wide ratio means cruise rpm at the prop of well below 2000 rpm. = Most of us are flying planes that can't swing the 7-8 foot diameter prop = needed to maintain efficiency at those low prop rpms. It also = complicates getting a prop made that will perform correctly, since it's = outside the area where most prop makers have worked. It's confused some = reputable prop makers here in the USA, even with the 2.85 ratio.=20 Again, congrats on the new design, Charlie On Wed, Sep 16, 2015 at 11:28 PM, Neil Unger = wrote: Gents, Finally the first PSRU with a reduction of 3.12 to = 1. Pictured is the basic box which is heavily based on Tracy=E2=80=99s = PSRU but with the larger reduction and 2 oil lubricated thrust = bearings on the prop shaft instead of a single sealed roller bearing in = Tracy=E2=80=99s. This psru will mount directly in place of Tracy's 2.85 = reduction PSRU with no modification. Now to put to test to see if the practice matches the theory. = Already found one fault. The =E2=80=9CO=E2=80=9D ring seal that seals = the main body of the PSRU to the base that attaches to the mounting = plate is outside all the attachment bolts, which means that the oil can = wick down the bolts and make a lovely mess of your pride and joy. Now = looking for more faults as this is easily fixed. Unlike Tracy's , this = PSRU is totally sealed with O rings to ease dismantling with no clean up = of whatever gasket sealer you have had to use. Now the terrible part and still undecided as I am yet to cost = a damper on the drive. Sadly it also is not cheap and may yet cost near = $500 for a =E2=80=9Dbit of rubber=E2=80=9D. Then comes a mounting plate = as made by Geoff Doddridge which he sells for around $400 USD. There is = no point in me trying to compete with Geoff as he does a magnificent job = at a cheap price. Freight is always a horrible price so he makes the = plate and there is no freight from Aust to be added. The total cost in Aust dollars (including Geoff=E2=80=99s = plate) will be around the $5000 which equates to $3500 USD. Then = freight of possibly $200. Currently looking at further reduction in = price if you source the gear set locally saving on freight both ways to = Aust and back. I will have to alter the way it is constructed so that = all the mods can be done by you the builder. Still looking! So far the progress. Neil. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_006A_01D0F380.21E25970 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Tracy,  Have hear many whispers about your = =E2=80=9Cinflexible=E2=80=9D =20 coupling, but just the thought makes me nervous.  Most of the money = on a=20 coupling is in the splined block that the engine drives, the extra Flex = part is=20 not a lot extra.  Have al;ready has two made and destroyed both in = testing=20 but the Poly and rubber (one each) survived.  The poly is by far = the=20 cheapest, but solid????  I just don=E2=80=99t feel right.  = Neil.
 
From: Tracy
Sent: Saturday, September 19, 2015 10:09 PM
Subject: [FlyRotary] Re: New psru
 
Looks like very nice work Neil, glad you picked up the ball and=20 ran.   I had the same comment as Charlie but as long as you = get a=20 suitable prop the 3.12 will work.  Only down side is I think the = minimum=20 BSFC 'sweet spot' of the rotary (about 5000 - 5500 rpm) may be below the = usable=20 cruise settings if propped for 8500 with a fixed pitch prop.  Not a = big=20 deal though.   When looking at my flying expenses, fuel turns = out to=20 be about the cheapest item  :-)
 
I would urge you to investigate 'going naked' with the = damper.  My=20 direct coupler version is at least as smooth as the rubber coupled = damper=20 version.  Only downside is it may not be suitable for metal props = but I=20 doubt you could find a suitable metal one for 3.12 ratio anyway.
 
Keep up the good work,
Tracy

Sent from my iPad

On Sep 18, 2015, at 09:15, Charlie England <flyrotary@lancaironline.net>=20 wrote:

I understand about debugging what you've = got,=20 before going off in a new direction. That's why I hated to bring it up = now.=20 :-)

The prop doesn't know how fast the engine is turning; it = just knows=20 how fast *it* is turning, and how fast it's moving through the air. I = think=20 that the problems start when the prop carver gets out of his comfort = zone,=20 which is 2700 design rpm and around 72" maximum diameter (usually = less). When=20 diameter goes up to 74"-76" and design rpm starts to drop, they seem = to get a=20 bit confused.  For those of us who never expect to exceed 7500 = rpm, with=20 cruise down around 5500-6000, a 3.12 ratio would mean prop at 2400 rpm = max,=20 and around 1900 at cruise. Nothing wrong with that if we could swing a = 7 foot=20 diameter prop, but with small, short legged a/c, you just can't do it. =

I couldn't find anything in my old emails about the prop you = had=20 problems with. What were its specs & mfgr? Was the 6000 rpm = static, or=20 full throttle in flight at low altitude? Did you ever get your engine = on a=20 dyno? I know what Lamar claimed for his p-port Renesis, but if those = were=20 'corrected' dyno numbers, they are pretty useless for real world = flying at=20 higher than sea level and anything above 'standard day' temperatures = (which=20 almost never happens). 250 HP seems pretty optimistic for a normally = aspirated=20 2 rotor actually flying in an a/c, but I hope you can get it working. = I've=20 been very tempted to find another Renesis core & send the housings = out to=20 get them p-ported, & if you're successful, you just might push me = over the=20 edge...

Charlie



On 9/17/2015 11:17 PM, Neil = Unger=20 wrote:
Charlie,  As usual anything is possible.  The 2.85 = ratio is=20 easier to alter the gear set , but by the time the = =E2=80=9Clittle=E2=80=9D mods are done=20 the cost climbs yet again.  May look at the possibility as all = the=20 drawings are done and alterations are now much simpler.  Will = get the=20 bugs out of this one first.  Most prop makers that I went to = just do=20 not want to hear =E2=80=9Crotary=E2=80=9D.  The revs are there = but the torque is not=20 compared to a lyc.  Much to learn in this area.  = Regards, =20 neil.
 
From: Charlie England
Sent: Friday, September 18, 2015 12:44 AM
Subject: [FlyRotary] Re: New psru
 
Hi Neil,=20
 
Congrats on your progress; it looks nice.  I like the idea = of=20 being able to source some of the parts locally, given that = international=20 shipping can cost more than a lot of parts.
 
The damper issue is a real bummer. IIRC, Tracy's been running a = later=20 version of his 2.85 directly coupled to an aluminum racing flywheel. = One or=20 two others have used light weight steel flywheels, but I think they = were=20 still using Tracy's damper mechanism, which doesn't look too = complicated to=20 build with precision machine tools that you obviously have access = to.
 
I know you'll hate to hear this question, but....are there = provisions=20 to use the 2.85 ratio in your design? The reason I ask is that many = of us=20 have no desire to turn the engine beyond 7500 rpm, and that wide = ratio means=20 cruise rpm at the prop of well below 2000 rpm. Most of us are flying = planes=20 that can't swing the 7-8 foot diameter prop needed to maintain = efficiency at=20 those low prop rpms. It also complicates getting a prop made that = will=20 perform correctly, since it's outside the area where most prop = makers have=20 worked. It's confused some reputable prop makers here in the USA, = even with=20 the 2.85 ratio.
 
Again, congrats on the new design,
 
Charlie
 
On Wed, Sep 16, 2015 at 11:28 PM, Neil = Unger <flyrotary@lancaironline.net>=20 wrote:
Gents,
=
           &n= bsp; =20 Finally the first PSRU with a reduction of 3.12  to 1.  = Pictured=20 is the basic box which is heavily based on Tracy=E2=80=99s PSRU = but with the=20 larger reduction and 2 oil lubricated thrust   bearings = on the=20 prop shaft instead of a single sealed roller bearing in = Tracy=E2=80=99s. =20 This psru will mount directly in place of Tracy's 2.85 reduction = PSRU with=20 no modification.
    Now to put to test to see if the practice = matches=20 the theory.  Already found one fault. The =E2=80=9CO=E2=80=9D = ring seal that seals=20 the main body of the PSRU to the base that attaches to the = mounting plate=20 is outside all the attachment bolts, which means that the oil can = wick=20 down the bolts and make a lovely mess of your pride and joy.  = Now=20 looking for more faults as this is easily fixed.  Unlike = Tracy's ,=20 this PSRU is totally sealed with O rings to ease dismantling with = no clean=20 up of whatever gasket sealer you have had to use.
    Now the terrible part and still undecided = as I am=20 yet to cost a damper on the drive.  Sadly it also is not = cheap and=20 may yet cost near $500 for a =E2=80=9Dbit of = rubber=E2=80=9D.  Then comes a mounting=20 plate as made by Geoff Doddridge which he sells for around $400 = USD. =20 There is no point in me trying to compete with Geoff as he does a=20 magnificent job at a cheap price.  Freight is always a = horrible price=20 so he makes the plate and there is  no freight from Aust to = be=20 added.
    The total cost in Aust dollars (including = Geoff=E2=80=99s=20 plate) will be around the $5000 which equates to $3500 USD.  = Then=20 freight of possibly $200.  Currently looking at further = reduction in=20 price if you source the gear set locally saving on freight both = ways to=20 Aust and back.  I will have to alter the way it is = constructed so=20 that all the mods can be done by you the builder.  Still=20 looking!
    So far the progress. =20 Neil.

--
Homepage:  http://www.flyrotary.com/
Archive = and=20 UnSub:   http://mail.lancaironline.net:81/lists/flyrotary= /List.html

=
 

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