From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] cooling modes
Date: Sat, 21 Nov 2020 09:51:14 +0800
References: <list-967274@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-967274@logan.com>
Message-Id: <919E723E-1BE0-4880-8728-EB2F4E8E62CC@gmail.com>

Hi Bruce

If I were starting again I would develop a belly mounted system =
something like Russell Sherwood dis in his Glasair IRG
Cheers

Steve

> On 21 Nov 2020, at 8:59 am, Bruce Cosgrove bcosgrove@mac.com =
<flyrotary@lancaironline.net> wrote:
>=20
> Hi Steve, Charlie, Matt, Roy and others
> I am in the process making up a  cooling system for a Tango 2 and was =
also planning to use the wedge shaped diffuser design, however the =
information that I have been reading from the homebuilt airplanes site =
discussing alternate approaches with less drag and improved efficiency? =
has me re thinking my design towards a belly mounted radiator.  The =
comments under the heading Successful Auto Conversion Trials, =
Tribulations and Tips, I found particularly interesting - in particular =
input from Russell and RJ6ejGUY who both have devised systems that are =
working well for them  Belly radiators may not be everyones idea of how =
to proceed but I like the idea of relatively unimpeded air flow and =
freeing up space in the cowling.  any feedback would be much =
appreciated.
>=20
> Bruce
>=20
> On 21 November 2020 at 10:00:57, Stephen Izett stephen.izett@gmail.com =
(flyrotary@lancaironline.net) wrote:
>=20
>> Nice work Charlie.=20
>>=20
>> Steve=20
>>=20
>> > On 21 Nov 2020, at 6:50 am, Charlie England ceengland7@gmail.com =
<flyrotary@lancaironline.net> wrote:=20
>> > =20
>> > My (untested in combat) version for my radiator looks similar, but =
because the inlet is offset, I had to use a turning vane to get flow =
into the lower front of the core. The outside doesn't give a good idea =
on how 'tight' the inner surface is. I had to use expanding foam to fill =
the inside, then re-shape, then glass over the foam. As I said, the back =
1/4-1/3 of the diffuser tapers tightly to almost touch the core at the =
back.=20
>> > =20
>> > After observing both rotary and piston installations that work, I'm =
beginning to think that turning vanes may be the 'good enough' vs =
fighting for perfection in diffuser shape. My oil cooler core has a much =
more elaborate vane setup, driven by the very short duct length and even =
greater offset to the bottom edge of the core.=20
>> > =20
>> > Charlie=20
>> > =20
>> > =20
>> > On 11/20/2020 4:22 PM, Stephen Izett stephen.izett@gmail.com wrote:=20=

>> >> Hi Roy=20
>> >> =20
>> >> Here is a photo of our Mocal 44 row oil cooler with diffuser. A =
K&M Streamline into a wedge.=20
>> >> Not sure of the dimensions of hand. The Mocal web site will have =
specs so you could get a rough idea of size.=20
>> >> I tested this one recently with a leaf blower approximating 100 =
knot air flow and in that test it was very even.=20
>> >> =20
>> >> Having said that, I tested our water radiator wedge diffuser when =
I built it years ago and had it reasonably even =20
>> >> measuring pressures across the exit face, but now instrumenting it =
in flight its flow is vastly uneven.=20
>> >> =20
>> >> I have found that the flow is dependant not only on getting the =
diffuser shape right according to the various papers (eg. K&W, London, =
Oblique Flow Diffusers - Streamline )=20
>> >> But importantly the environment it ends up in. The papers share =
data for ideal conditions with for example unobstructed exit air paths.=20=

>> >> My thoughts now are that this has a significant impact on the =
performance and therefore the advantage of instrumenting in flight and =
reshaping for actual conditions.=20
>> >> =20
>> >> The data I collected yesterday of our H2O diffuser reveals that =
the air flow in various points across the face are very different.=20
>> >> Simplified, if I average the pressures at the five points I =
measured, then comparatively the back is up 20%, the centre up 25% and =
the front down 60% from that average figure.=20
>> >> I=E2=80=99m figuring a 20% difference is probably OK, but my front =
to back/middle difference of ~80% down in the front top of that radiator =
may hold significant room for improvement.=20
>> >> Further, my data suggests that as IAS rises those differences are =
amplified. =20
>> >> So I am now targeting the modifications for our worst case =
conditions of WOT sea level ~200hp and initial climb numbers of 115KIAS.=20=

>> >> =20
>> >> Cheers.=20
>> >> =20
>> >> Steve Izett=20
>> >> =20
>> >> =20
>> >> =20
>> >>> On 21 Nov 2020, at 3:37 am, ROY GLENN rglenn14@sbcglobal.net =
<flyrotary@lancaironline.net> wrote:=20
>> >>> =20
>> >>> Could some ne post a photo of their wedge shape and dimensions.=20=

>> >>> Thanks Roy=20
>> >>> =20
>> >>> --=20
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>> > =20
>> > <rad duct1.JPG>--=20
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