X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from rwcrmhc13.comcast.net ([216.148.227.153] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1184009 for flyrotary@lancaironline.net; Mon, 19 Jun 2006 18:59:43 -0400 Received-SPF: none receiver=logan.com; client-ip=216.148.227.153; envelope-from=hoursaway1@comcast.net Received: from rmailcenter73.comcast.net (rmailcenter73.comcast.net?[204.127.197.155](misconfigured sender)) by comcast.net (rwcrmhc13) with SMTP id <20060619225853m1300g0qehe>; Mon, 19 Jun 2006 22:58:58 +0000 Received: from [24.11.214.194] by rmailcenter73.comcast.net; Mon, 19 Jun 2006 22:58:47 +0000 From: hoursaway1@comcast.net To: "Rotary motors in aircraft" Subject: Ivoprop Date: Mon, 19 Jun 2006 22:58:47 +0000 Message-Id: <061920062258.6811.44972C26000E212D00001A9B2207300793CE970E990E9C9D9A0108@comcast.net> X-Mailer: AT&T Message Center Version 1 (Apr 11 2006) X-Authenticated-Sender: aG91cnNhd2F5MUBjb21jYXN0Lm5ldA== MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_6811_1150757927_0" --NextPart_Webmail_9m3u9jl4l_6811_1150757927_0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Ed; This is Dave Cook, we met at several Sun-n-Fun flyin's including this year. Do you (or anyone else reading) know anything about the Ivoprop magnum inflight adjustable, am still shopping for a prop, will need to make a choice VERY soon. Application will be; RV6A 13B Turrentine build w/mods done, RWS EC2, EM2 & PSRU-B, 3.5" throttlebody. Thanks, David. -------------- Original message -------------- From: "Ed Anderson" > Thanks Charlie, I'll read the Low Flow Articles. > > Its no secret that you reduce exit airflow drag by accelerating it to the > outside airstream velocity. We also know that if we make an area smaller > that the air velocity will speed up. I will be very interested in how they > do it without incurring drag. It would take a higher pressure area in front > of the narrow exit in order to force the hot air through a smaller area. > Since mass flow will remain constant, you can increase the velocity and get > the same amount of air through a smaller exit area or increase the area and > get a larger volume of air through at a slower velocity. > > But when you decrease the exit area you generally will experience pressure > increase in front of the narrow area (which in this case is inside the > cowl). That pressure increase in back of a core or fins would tend to > oppose the air flow coming in to the determent of good cooling. If they had > exhaust augmentation then I could see how that would work. > > But, I should stop speculating and read the articles and see if that > improves my understanding of how a smaller exit improves cooling. > > Ed > > > ----- Original Message ----- > From: "Charlie England" > To: "Rotary motors in aircraft" > Sent: Saturday, June 17, 2006 9:00 PM > Subject: [FlyRotary] Re: Exit area smaller than intake was External > Diffusion > > > > I've read several articles that talk about making the exit smaller than > > the inlet. The key was not exhaust augmentation, but exit ducting that's > > effectively the reverse of the 'pressure recovery' of the inlet. Think of > > the P-51. IIRC, the CAFE Foundation articles talk about it. > > > > http://cafefoundation.org/v1/research.htm > > > > Try the 'local flow' articles (BTW, look at the most efficient exit shape; > > it's not gills or a 'reverse NACA'). > > > > I think that the old 130% of inlet ideas gained popularity before > > homebuilders really understood how to get air in & out of a cowling > > efficiently. If you look at that Mustang II in the exit area you will > > almost certainly see some significant changes from 'stock' below the > > cylinders & around the bottom of the firewall. I talked to Tracy Saylor > > (sp?), owner of the 180 hp, 230+ mph RV-6 about how he does it, & his mods > > to guide the air after it cools the cylinders & oil are pretty impressive. > > > > Charlie > > > > Ed Anderson wrote: > > > >> Ok, thanks, Thomas. > >> > >> I understood correctly 135% OF the exit - just conveyed my understanding > >> improperly. Yes, if you have them already scanned I would like a copy. > >> I hope there are a few photos as I am interested whether or not they may > >> be using exhaust augmentation (whether they realize it or not). > >> > >> Ed > >> > >> ----- Original Message ----- From: "Thomas y Reina Jakits" > >> > >> To: "Rotary motors in aircraft" > >> Sent: Saturday, June 17, 2006 4:30 PM > >> Subject: [FlyRotary] Re: Exit area smaller than intake was External > >> Diffusion > >> > >> > >>> Ed, > >>> there is a mistake as the intake is not 135%bigger than, but 135% of the > >>> exit. > >>> It still makes it 1.35 times bigger than the exit. > >>> > >>> I posted this last in April 2005, the latest response to the subject was > >>> on > >>> 14th of december by Monty Roberts. > >>> It always starts with a question to verify the intake bigger than exit > >>> claim,but "no mistake" that's what it is! > >>> > >>> Please search the archive or let me know if you want me to repost the > >>> post! > >>> It was about Brian Schmidtbauers Mustang II being the fastest around! > >>> Also menetioned is Dave Anders' RV-4, details in the CAFE report. > >>> I have the essential pages of the Kitplanes article scanned, let me know > >>> if > >>> you want them emailed.... > >>> > >>> It just shows that rules of thumb are not always the best solution. Most > >>> likely just the most economic one to build..... > >>> > >>> Thomas > >>> > >>> PS: Search "Kitplanes" and go for the 14th Dec.,2005 posts!! > >>> > >>> > >>> ----- Original Message ----- From: "Ed Anderson" > >>> > >>> To: "Rotary motors in aircraft" > >>> Sent: Saturday, June 17, 2006 6:35 AM > >>> Subject: [FlyRotary] Exit area smaller than intake was External > >>> Diffusion > >>> > >>> > >>>> That's very interesting, Thomas. I too recall seeing in several places > >>>> reference to > >>>> exit area being some multiple of the inlet with the ratios varying from > >>>> 1.2 -1.7. > >>>> There certainly could be some kind of phenomena I have not hear of or > >>>> read about, but seems strange you would ever have your intake area more > >>> > >>> than > >>> > >>>> the exit area. But assuming no error then it would appear to me that > >>>> external diffusion is taking place. > >>>> > >>>> What that indicates to me is that the exit area (what ever size > >>>> it was) provides adequate airflow for cooling flow through the engine > >>>> compartment.(assumption is the engine did not get cooked). Enough air > >>> > >>> mass > >>> > >>>> HAD to leave the cowling sufficient to carry away the necessary BTUs of > >>>> heat. That said, then if the inlets were 135% larger than the exit > >>>> area, > >>>> then air HAD to be spilling around the inlet or area of external > >>> > >>> diffusion. > >>> > >>>> The air molecules in this part of the airflow (external to the cowl) > >>>> then > >>>> contributed NOTHING to carrying away heat from the engine, but do add > >>>> to > >>>> drag - that left only > >>>> the air that past through the core (or over the cooling fins of the > >>> > >>> cylinder > >>> > >>>> head) to provide for cooling. Since this air has now been heated and > >>> > >>> expands > >>> > >>>> to a larger volume, you traditionally need a larger exit area to > >>> > >>> accommodate > >>> > >>>> this large volume of heated air. That air must leave the engine > >>>> compartment via the exit. So I just am unable to come up with a > >>>> scenario > >>>> where having an inlet larger than the exit area would be beneficial. > >>>> > >>>> Having said that, it did just trigger a thought about why this might be > >>>> tried and > >>>> how it might be made to work. > >>>> . > >>>> We do know that for air exiting the cowl to provide minimum drag it > >>> > >>> ideally > >>> > >>>> should be accelerated back to the airstream velocity before > >>>> intermixing. > >>> > >>> We > >>> > >>>> can theoretically do this by taking the larger volume of heat air and > >>>> designing an exit area > >>>> which would accelerate the air molecules increasing the velocity of > >>>> the > >>>> exiting air and reducing drag. However, to accelerate the cowl air > >>> > >>> velocity > >>> > >>>> to anything really meaningful, > >>>> would require added energy. This leads me to believe that perhaps an > >>>> exhaust augmentation system could be used to provide increased velocity > >>>> to > >>>> the exiting air using the energy in > >>>> the exhaust flow. If the exiting airflow velocity is increased over > >>>> than > >>>> normally associated with exiting air, then more air of course could > >>>> flow > >>>> through a smaller opening, this would perhaps permit one to have a > >>>> smaller > >>>> exit area than intake area and still > >>>> get good cooling and low cooling drag. > >>>> > >>>> So with an exhaust augmentation system "helping" the air in the cowl to > >>> > >>> exit > >>> > >>>> quicker and at a higher velocity, I can see where a smaller exit area > >>> > >>> might > >>> > >>>> indeed be workable. > >>>> But, without an exhaust augmentation system, I just don't see how a > >>> > >>> smaller > >>> > >>>> exit area would be beneficial. > >>>> > >>>> Any mention of exhaust augmentation?? > >>>> > >>>> Well that my $0.02 worth on the topic > >>>> > >>>> Ed > >>>> > >>>> Ed Anderson > >>>> Rv-6A N494BW Rotary Powered > >>>> Matthews, NC > >>>> eanderson@carolina.rr.com> Hi Steve, > >>> > > > > > > > > > > -- > > Homepage: http://www.flyrotary.com/ > > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > > > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ --NextPart_Webmail_9m3u9jl4l_6811_1150757927_0 Content-Type: text/html Content-Transfer-Encoding: 8bit
Ed;  This is Dave Cook, we met at several Sun-n-Fun flyin's including this year. Do you (or anyone else reading) know anything about the Ivoprop magnum inflight adjustable,  am still shopping for a prop, will need to make a choice VERY soon. Application will be;  RV6A  13B Turrentine build w/mods done, RWS EC2, EM2 & PSRU-B, 3.5" throttlebody.  Thanks, David.
 
-------------- Original message --------------
From: "Ed Anderson" <eanderson@carolina.rr.com>

> Thanks Charlie, I'll read the Low Flow Articles.
>
> Its no secret that you reduce exit airflow drag by accelerating it to the
> outside airstream velocity. We also know that if we make an area smaller
> that the air velocity will speed up. I will be very interested in how they
> do it without incurring drag. It would take a higher pressure area in front
> of the narrow exit in order to force the hot air through a smaller area.
> Since mass flow will remain constant, you can increase the velocity and get
> the same amount of air through a smaller exit area or increase the area and
> get a larger volume of air through at a slower velocity.
>
> But when you decrease the exit area you generally will experie nce pressure
> increase in front of the narrow area (which in this case is inside the
> cowl). That pressure increase in back of a core or fins would tend to
> oppose the air flow coming in to the determent of good cooling. If they had
> exhaust augmentation then I could see how that would work.
>
> But, I should stop speculating and read the articles and see if that
> improves my understanding of how a smaller exit improves cooling.
>
> Ed
>
>
> ----- Original Message -----
> From: "Charlie England"
> To: "Rotary motors in aircraft"
> Sent: Saturday, June 17, 2006 9:00 PM
> Subject: [FlyRotary] Re: Exit area smaller than intake was External
> Diffusion
>
>
> > I've read several articles that talk about making the exit smaller than
> > the inlet. The key was not exhaust augmenta tion, but exit ducting that's
> > effectively the reverse of the 'pressure recovery' of the inlet. Think of
> > the P-51. IIRC, the CAFE Foundation articles talk about it.
> >
> > http://cafefoundation.org/v1/research.htm
> >
> > Try the 'local flow' articles (BTW, look at the most efficient exit shape;
> > it's not gills or a 'reverse NACA').
> >
> > I think that the old 130% of inlet ideas gained popularity before
> > homebuilders really understood how to get air in & out of a cowling
> > efficiently. If you look at that Mustang II in the exit area you will
> > almost certainly see some significant changes from 'stock' below the
> > cylinders & around the bottom of the firewall. I talked to Tracy Saylor
> > (sp?), owner of the 180 hp, 230+ mph RV-6 about how he does it, & his mods
> > to guide the air after it cools the cylinders & oil are pretty impressive.
> >
> > Charlie
> >
> > Ed Anderson wrote:
> >
> >> Ok, thanks, Thomas.
> >>
> >> I understood correctly 135% OF the exit - just conveyed my understanding
> >> improperly. Yes, if you have them already scanned I would like a copy.
> >> I hope there are a few photos as I am interested whether or not they may
> >> be using exhaust augmentation (whether they realize it or not).
> >>
> >> Ed
> >>
> >> ----- Original Message ----- From: "Thomas y Reina Jakits"
> >>
> >> To: "Rotary motors in aircraft"
> >> Sent: Saturday, June 17, 2006 4:30 PM
> >> Subject: [FlyRotary] Re: Exit area smaller than intake was External
> >> Diffusion
> >>
& gt; >>
> >>> Ed,
> >>> there is a mistake as the intake is not 135%bigger than, but 135% of the
> >>> exit.
> >>> It still makes it 1.35 times bigger than the exit.
> >>>
> >>> I posted this last in April 2005, the latest response to the subject was
> >>> on
> >>> 14th of december by Monty Roberts.
> >>> It always starts with a question to verify the intake bigger than exit
> >>> claim,but "no mistake" that's what it is!
> >>>
> >>> Please search the archive or let me know if you want me to repost the
> >>> post!
> >>> It was about Brian Schmidtbauers Mustang II being the fastest around!
> >>> Also menetioned is Dave Anders' RV-4, details in the CAFE report.
> >>> I have the essential pages of the Kitplanes article scanned, let me know
> >>> if
> >>> you want them emailed....
> >>>
> >>> It just shows that rules of thumb are not always the best solution. Most
> >>> likely just the most economic one to build.....
> >>>
> >>> Thomas
> >>>
> >>> PS: Search "Kitplanes" and go for the 14th Dec.,2005 posts!!
> >>>
> >>>
> >>> ----- Original Message ----- From: "Ed Anderson"
> >>>
> >>> To: "Rotary motors in aircraft"
> >>> Sent: Saturday, June 17, 2006 6:35 AM
> >>> Subject: [FlyRotary] Exit area smaller than intake was External
> >>> Diffusion
> >>>
> >>>
> >>>> That's very interesting, Thomas. I too recall seeing in several places > >>>> reference to
> >>>> exit area being some multiple of the inlet with the ratios varying from
> >>>> 1.2 -1.7.
> >>>> There certainly could be some kind of phenomena I have not hear of or
> >>>> read about, but seems strange you would ever have your intake area more
> >>>
> >>> than
> >>>
> >>>> the exit area. But assuming no error then it would appear to me that
> >>>> external diffusion is taking place.
> >>>>
> >>>> What that indicates to me is that the exit area (what ever size
> >>>> it was) provides adequate airflow for cooling flow through the engine
> >>>> compartment.(assumption is the engine did not get cooked). Enough air
> >>>
> >>> mass
> >>>
> >>>> ; HAD to leave the cowling sufficient to carry away the necessary BTUs of
> >>>> heat. That said, then if the inlets were 135% larger than the exit
> >>>> area,
> >>>> then air HAD to be spilling around the inlet or area of external
> >>>
> >>> diffusion.
> >>>
> >>>> The air molecules in this part of the airflow (external to the cowl)
> >>>> then
> >>>> contributed NOTHING to carrying away heat from the engine, but do add
> >>>> to
> >>>> drag - that left only
> >>>> the air that past through the core (or over the cooling fins of the
> >>>
> >>> cylinder
> >>>
> >>>> head) to provide for cooling. Since this air has now been heated and
> >>>
> >>> expands
> >& gt;>
> >>>> to a larger volume, you traditionally need a larger exit area to
> >>>
> >>> accommodate
> >>>
> >>>> this large volume of heated air. That air must leave the engine
> >>>> compartment via the exit. So I just am unable to come up with a
> >>>> scenario
> >>>> where having an inlet larger than the exit area would be beneficial.
> >>>>
> >>>> Having said that, it did just trigger a thought about why this might be
> >>>> tried and
> >>>> how it might be made to work.
> >>>> .
> >>>> We do know that for air exiting the cowl to provide minimum drag it
> >>>
> >>> ideally
> >>>
> >>>> should be accelerated back to the airstream velocity before
> &g t;>>> intermixing.
> >>>
> >>> We
> >>>
> >>>> can theoretically do this by taking the larger volume of heat air and
> >>>> designing an exit area
> >>>> which would accelerate the air molecules increasing the velocity of
> >>>> the
> >>>> exiting air and reducing drag. However, to accelerate the cowl air
> >>>
> >>> velocity
> >>>
> >>>> to anything really meaningful,
> >>>> would require added energy. This leads me to believe that perhaps an
> >>>> exhaust augmentation system could be used to provide increased velocity
> >>>> to
> >>>> the exiting air using the energy in
> >>>> the exhaust flow. If the exiting airflow velocity is increased over
> >>>> t han
> >>>> normally associated with exiting air, then more air of course could
> >>>> flow
> >>>> through a smaller opening, this would perhaps permit one to have a
> >>>> smaller
> >>>> exit area than intake area and still
> >>>> get good cooling and low cooling drag.
> >>>>
> >>>> So with an exhaust augmentation system "helping" the air in the cowl to
> >>>
> >>> exit
> >>>
> >>>> quicker and at a higher velocity, I can see where a smaller exit area
> >>>
> >>> might
> >>>
> >>>> indeed be workable.
> >>>> But, without an exhaust augmentation system, I just don't see how a
> >>>
> >>> smaller
> >>>
> >>>> exit area would be beneficial.
> >>>>
> >>>> Any mention of exhaust augmentation??
> >>>>
> >>>> Well that my $0.02 worth on the topic
> >>>>
> >>>> Ed
> >>>>
> >>>> Ed Anderson
> >>>> Rv-6A N494BW Rotary Powered
> >>>> Matthews, NC
> >>>> eanderson@carolina.rr.com> Hi Steve,
> >>>
> >
> >
> >
> >
> > --
> > Homepage: http://www.flyrotary.com/
> > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
> >
>
>
>
> --
> Homepage: http://www.flyrotary.com/
> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
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