X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost04.isp.att.net ([204.127.217.104] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6505994 for flyrotary@lancaironline.net; Mon, 07 Oct 2013 17:43:09 -0400 Received-SPF: none receiver=logan.com; client-ip=204.127.217.104; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-98-85-147-248.mco.bellsouth.net[98.85.147.248]) by isp.att.net (frfwmhc04) with SMTP id <20131007214235H0400aok2ee>; Mon, 7 Oct 2013 21:42:35 +0000 X-Originating-IP: [98.85.147.248] From: "Bill Bradburry" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Re: Prop and PSRU efficiency Date: Mon, 7 Oct 2013 17:42:45 -0400 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01CEC384.A24D5700" X-Mailer: Microsoft Office Outlook 11 Thread-Index: Ac7DlVVcYOTr+7JXQDmipYBVTjuOdwAEJFRw X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 This is a multi-part message in MIME format. ------=_NextPart_000_0009_01CEC384.A24D5700 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Based on the below statement, where would Tracy's planet gear system fall? PSRUs have losses inherent in their gearsets or belts. Lay people have often speculated that these losses are up to 40 hp in the case of a 200 hp class drive. This is absurd as it would represent about 30,000 watts being dissipated as heat. If this was in fact true, the case or belts would melt in just a few minutes. Typical losses for single mesh spur and helical gears is around 2-2.5%. HTD belts run at 3-4%. Twin mesh helical gearsets would then have perhaps a 6% loss as worst case including bearing losses. The statement came from: http://www.sdsefi.com/air51.htm B2 _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry Sent: Monday, October 07, 2013 3:42 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Prop and PSRU efficiency Mark, They would be included if the engine was tested on a dyno, so I consider them to be part of the engine. But not so the PSRU if measuring from the flywheel. Ernest, I don't know what you mean by .98 to .99?? Certainly you don't think it would only be a loss of 1 or 2%!?? It would have to be in the range of 10 to 20 HP or even greater. That is 5 to 10% in our HP range. Just the loss due to prop efficiency is in the range of 30 HP! Bill _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle Sent: Monday, October 07, 2013 1:26 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Prop and PSRU efficiency Bill, While you're at it don't forget to account for the water pump and alternator(s). Mark S. On Mon, Oct 7, 2013 at 12:18 PM, Bill Bradburry wrote: I have asked this question a couple of times and no one has hazarded a guess. How much HP is lost from our engines due to the PSRU? I have been interested in determining what the HP output of my engine is and that info would be needed for that estimation. They tell me that most props are about 80-85% efficient, so to calculate the hp, you take the difference between your climb rate and your glide descent rate at the same airspeed, multiplied by the weight, and then divided by 33000. Wt * V / 33000 = HP This would be the prop HP, so to get the prop flange HP, you would divide by the prop efficiency, between .8 and .85. To get the engine flywheel HP, you would have to add something for the loss of the PSRU. Is anyone willing to take a shot at that number?? Third or forth chance! :>) Bill B -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0009_01CEC384.A24D5700 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Based on the below statement, where = would Tracy’s = planet gear system fall?

 

PSRUs have losses inherent in their gearsets or belts. Lay people have often speculated that these losses are up to 40 hp in the case of a 200 hp = class drive. This is absurd as it would represent about 30,000 watts being = dissipated as heat. If this was in fact true, the case or belts would melt in just = a few minutes. Typical losses for single mesh spur and helical gears is around 2-2.5%. HTD belts run at 3-4%. Twin mesh helical gearsets would then = have perhaps a 6% loss as worst case including bearing = losses.

The statement came = from:

 

http://www.sdsefi.com/air51.htm<= /a>

 

B2

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry
Sent: Monday, October 07, = 2013 3:42 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Prop and PSRU efficiency

 

Mark,

 

They would be included if the = engine was tested on a dyno, so I consider them to be part of the engine.  But = not so the PSRU if measuring from the flywheel.

 

Ernest,

=

 

I don’t know what you mean by = .98 to .99??  Certainly you don’t think it would only be a loss of 1 = or 2%!??  It would have to be in the range of 10 to 20 HP or even greater.  That is 5 to 10% in our HP range.  Just the loss due = to prop efficiency is in the range of 30 HP!

 

Bill

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Monday, October 07, = 2013 1:26 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Prop and PSRU efficiency

 

Bill,

 

While you're at it don't forget to account for the water pump = and alternator(s).

 

Mark S.

 

On Mon, Oct 7, 2013 at 12:18 PM, Bill Bradburry <bbradburry@bellsouth.net> = wrote:

I have asked this question a couple of times and no one has = hazarded a
guess.

How much HP is lost from our engines due to the PSRU?  I have = been
interested in determining what the HP output of my engine is and that = info
would be needed for that estimation.

They tell me that most props are about 80-85% efficient, so to calculate = the
hp, you take the difference between your climb rate and your glide = descent
rate at the same airspeed, multiplied by the weight, and then divided = by
33000.

Wt * V / 33000 =3D HP

This would be the prop HP, so to get the prop flange HP, you would = divide by
the prop efficiency, between .8 and .85.

To get the engine flywheel HP, you would have to add something for the = loss
of the PSRU.

Is anyone willing to take a shot at that number??  Third or forth = chance!
:>)

Bill B




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

 

------=_NextPart_000_0009_01CEC384.A24D5700--