----- Original Message -----

From: hoursaway1@comcast.net

To: Rotary motors in aircraft

Sent: Tuesday, June 20, 2006 11:32 PM

Subject: [FlyRotary] Re: Ivoprop

Thanks Ed, they did respond & I have decided to try the Ivo Mag. the one for sale is the high pitch so we will see how the numbers come out, our setup is similar to Bill E. and yours,  w/intake for oil cooler under eng. oil pan line below prop, throttle body opening is new style Van's below cowel,  thanks also to all that responded this is truly a great source of info & knowledge.  Thanks again,    David

 

-------------- Original message --------------
From: "Ed Anderson" <eanderson@carolina.rr.com>

Dave, I have absolute no experience with any prop other than the fixed pitch wood Performance Propellers.  Several guys on this list, however do have in-flight adjustable IVO props, so they will probably respond.

 

Ed

----- Original Message -----

From: hoursaway1@comcast.net

To: Rotary motors in aircraft

Sent: Monday, June 19, 2006 6:58 PM

Subject: [FlyRotary] Ivoprop

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 augment a 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 th e 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 sc anned, 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 pl aces > >>>> 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 bef ore
> &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
> >>>
> >& gt;>> 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/